What is Structures: Definition and 350 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. Crazy Old Coot

    Crazy Old Coot says "Hello"

    Greetings, I am almost 70 years old now, and have retired from formal employment. This was no my decision, but Company policy. I've been making stuff since I was knee-high to a grasshopper. Not everything worked out first time... I love hydraulics, and structures with triangulation. I have built...
  2. K

    I Observation of structures at ∼17 and ∼38 MeV/c2 in the γγ invariant mass spectra

    I'm waiting for PADME run 3 and MEG II from Russia not Hungry could someone review arXiv:2311.18632 (hep-ex) [Submitted on 30 Nov 2023] Observation of structures at ∼17 and ∼38 MeV/c2 in the γγ invariant mass spectra in pC, dC, and dCu collisions at plab of a few GeV/c per nucleon Kh.U...
  3. shivajikobardan

    Best courses to learn Data Structures and Algorithms in C/C++/JS

    Do you know any such good resources? I want to improve my problem solving skills. I also want to practice competitive programming, so any good courses for that? I want to practice pointers any good courses for that?
  4. S

    I Expansion-Collapse cycle in cosmological structures?

    Concerning cosmological structures (like galaxies, clusters of galaxies, gas bodies, superclusters...etc) if the elements that make them are close enough they will be attracted towards each other by gravity. Contrarily, if they are sufficiently far apart they will get further away following the...
  5. M

    Engineering Calculating the safe load of a glued structure with given shear stress

    I have tried to calculate the safe load with the equation of maximum shear stress, A = 4*6*10^-4, and the given shear stress 5MPa, but I couldn't seem to get the right answer which is 18kN.
  6. G

    Analysis of systems in equilibrium: articulated structures

    Figure: My attempt at a Solution: We calculate REACTIONS: $$\sum F_x=0\rightarrow \boxed{Bx=0}\qquad \sum F_y=0\rightarrow By+A=50$$ $$\sum M_B=0\rightarrow \boxed{A=25\, \textrm{kN}}\quad \boxed{B=25\, \textrm{kN}}$$ KNOT B: $$\alpha \rightarrow \alpha =90-40=50\, \textrm{º}$$ $$\beta...
  7. robphy

    Space/Spacetime Metrics: Comparing Routes in PHY 101

    [Moderator's note: Spin off from previous thread due to more advanced level of discussion.] The above is true even on an ordinary position-vs-time graph in PHY 101, when "distance" is appropriately defined. OOPS (Thanks @PeterDonis ) This turns out to be true only in the Galilean/Newtonian...
  8. shivajikobardan

    MHB What are structures of big data?

    I am learning about 3 V's of big data. I am learning about variety at the moment. They say variety represents variety of formats, data sources and structures. I understand format might be txt, audio, video files etc. Sources might be different sources of data. But what is structures of data?
  9. shivajikobardan

    Comp Sci What are structures of big data?

    I am learning about 3 V's of big data. I am learning about variety at the moment. They say variety represents variety of formats, data sources and structures. I understand format might be txt, audio, video files etc. Sources might be different sources of data. But what is structures of data? I...
  10. P

    Having trouble deducing 4 organic structures (High school exam qn)

    Summary:: Please see picture below The dotted line at Test 3 means to continue using the above solution, and add NaOH with the teat pipette. The dotted line separating tests 3 and 4 should be a hard line, which means to use a fresh sample of FA10 and perform the test. It is also known that...
  11. N

    A Classifying atomic chains in Amorphous Structures

    Here are two examples of chains. The end pairs of atoms are 8.0 angstroms and 9.2 angstroms apart respectively.
  12. C

    Ans: Resonance Structures: Checking Answers Correctness

    Summary:: I would like to know if my answers of each resonance structure of the eight questions is correct or not. I think the Inductive effect (induction) attracts electrons and affects up to three bonds as electron attracting group. And the Mesomeric effect affects Pi- bonds as long as there...
  13. P

    Can a compound have multiple structures?

    Can a compound have multiple structures? For example, I found two different versions of Sodium dichloride (Cl2Na-). https://pubchem.ncbi.nlm.nih.gov/compound/22590707 https://pubchem.ncbi.nlm.nih.gov/compound/57736105 What makes the difference between which of these compound structures is...
  14. M

    Engineering Common way to determine motor size/power in mechanical structures?

    Hi all, I have the following situation: I need to determine the minimum force needed for a motor to move the load (75 N) at the end of the beam. I added the forces in a FBD and did the sum of forces and moment calculations (see below). Is this calculation correct and what would be the next...
  15. A

    B Understanding Crystal Structures: Energy Considerations

    This questions is hovering on my mind from a long time. Why would something which does not have life would want to be in such a beautiful neighborhood, while the world is so much disordered. What causes them to be in that regular array and how they choose which crystal structure is suitable for...
  16. Helena Wells

    A Crystal structures and number of bonds of each atom

    Is there a general rule for a crystal structure how many bonds each atom in the crystal lattice will make ?For example Si has a face centered cubic structure so it makes 4 bonds regardless of the fact Si has 4 valence electrons?
  17. Physicsman788

    What is Boundary Interaction in Echolocation and Internal Body Structures?

    What is a boundary and how can boundary interactions be used in echolocation and examining internal body structures?
  18. S

    I The adjective "finite" applied to algebraic structures

    The adjective "finite" applied to many algebraic structures (e.g. groups, fields) indicates a set with a finite number of elements. However, (as I understand it) "finite algebra" refers to a finitely generated algebra. Are there other examples where "finite" means finite in some respect but...
  19. S

    Nomenclature questions -- Naming structures when given compounds

    How would I name the following two compounds? My guess is that the first one would be 3-bromophenyl 1-chloro ketone and the second one (4Z)-3-sec butyl-hex-4-en-1-yne. Am I correct? Thank you
  20. DennisN

    Video: SF ships/structures size comparison

    Here's a nice video which is a size comparion of a great number of fictional structures from science fiction novels, movies and games. The video is called "FICTIONAL STARSHIPS Size COMPARISON" but it includes some structures I personally wouldn't call starships, but anyway... Enjoy...
  21. F

    Variable, Data Type and Array Data Structures

    Hello, In Python and other programming languages, data can be of different types: integer, float, string, Boolean. On the other hand, Data structures are containers of data items which can (or not) have the same data type. A variable, when created, has: a) name (a piece of data stored in...
  22. L

    A Taxicab Numbers and Their Structures: Seeking Discussions

    Hi, I'm new to PF, but was hoping that there might be people on this forum with an interest in Taxicab numbers, particular on the "structure" of such integer sequences. If yes, would be delighted to hear from you.
  23. I

    Learning Data Structures in Java: Circular Queue

    Summary:: I have recently started with data structures in java and I tried doing this Program .But I have few confusions. 1.How do I write the main() of the program? 2.What are we supposed to do with the value returned by function pop()? If anyone could point out if there are any errors and...
  24. Whipley Snidelash

    History Exploring Megalithic Structures & Ancient Civilizations

    I have been watching lately many YouTube videos on megalithic structures. I am talking about the most ancient stonework in South America where the stones are cut and fit almost perfectly. These stones have many common features. They are cut to fit almost perfectly. They are all beveled at their...
  25. I

    Memorizing Organic Chemistry: Structures, Reactions & Tips

    For organic chemistry, what is important to memorize when I am reading a textbook? Should I memorize the structures and names of different organic compounds when they are described as examples? Or is it more important to memorize the organic reactions? Also, does anyone have any tips on how to...
  26. F

    Nested structures and indentation in Python

    Hello! In the context of Python, indentation is very important and mandatory. The entire code is separated into blocks and each block has its own indentation. Two blocks with the same indentation belong are the same block unless the blocks are separated by a block with less indentation...
  27. W

    Python Data Structures: Guessing a Number

    Hi all, Trying to right a program in Python asking user to guess a number ( integer in finite range) until they make a correct guess, though I want to warn user when guess is too high --asking that they choose a lower number ,and same for when the guess is low, asking them to choose a higher...
  28. Frigus

    How to remember the structures of purines and pyrimidines?

    I have drawn structure of purines and pyrimidines literally 14 times but still I am not able to recall the structures of these tiny monsters after few days of learning them. Can you please tell me how you remembered these structures. Thanks😃.
  29. A

    Statically Indeterminate Truck - Finding reaction forces at supports

    If you do the sum of vertical forces and sum of moments, you're always left with an unknown. Vertical Forces: Ray + Rby + Rcy = 59kN + 45kN (1) Sum of Moments about A: (59 x 1.85) - (Rby x 3.7) - (Rcy x 4.8) + (45 x 6.5) = 0...
  30. okandrea

    Structural Systems: Steel and Reinforced Concrete (RC)

    I've been looking over precedents for a design project and I noticed that the most commonly used systems are either steel or reinforced concrete structural systems. Is it possible for a steel structural system to be connected to a reinforced concrete structural system? If so, how does it work...
  31. S

    I Why are crystals more conductive then amorphous structures?

    Hey guys basically why are copper crystals more conductive then the corresponding amorphous structure? I know generally that electrical conductivity is reliant on: σ = (e2 * (vf)2 n τ)/3 My attempt of understanding is that the crystal structures are made up of unit cells which implies every...
  32. 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...
  33. Robert House

    What's the best software to use when designing 2D floor plans for structures?

    What's the best software to use when designing 2D floor plans for structures?
  34. AlexVille

    B Reading a Book about Air Sustained Structures....

    As in constructions that consist of a membrane of some textile and are sustained by pressurized air bombs. A paragraph mentions that in the face of strong winds or snowfall the internal pressure rises... but i don´t understand exactly why is that. I´m just curious and would like to know. pd...
  35. A

    I Formation of dark matter structures

    I can't understand how dark matter can form structures from the initial near uniform distribution as shown in simulation like those of the Eagle project http://icc.dur.ac.uk/Eagle/index.php. I understand how the initial density fluctuation are amplified and dark (and ordinary) matter start to...
  36. M

    Biology What are the vascular structures of this cucumber cross section?

    We were asked to label the vasculature structures of a cucumber cross section (complex tissue). I just wanted to know if my labels were accurate. Image attached 1. Xylem 2.— 3. Sieve elements 4. Phloem
  37. mfb

    A Binding energies with muonic structures

    Summary: Could a hierarchical structure of protons, muons and positrons be stable without the weak interaction? This discussion started here, I quote the relevant previous comments and then reply: @Vanadium 50: (mu- e+) is muonium, not true muonium - it is hydrogen-like where the muon...
  38. A

    B Matter/antimatter hybrid atomic structures?

    I know that direct interaction of opposite chirality(?) particles results in annihilation(eg. proton and antiproton). And I have read that proximity of quark and antiquark, even if in separate subatomic particles, results in at least partial annihilation(eg. Antineutron and proton). But I am...
  39. N

    How would we increase the rotation rate of very large structures in deep space?

    Imagine a 400-meter-long pipe with a 1600-meter diameter, floating in inter-planetary space. It is spinning at 0.5 gravity along its major axis and there are no secondary-axes spins. We need to increase rotation to 0.85 g. Its density is a uniform 2.3 kg/m³ and it weighs 49,120,056 kg. Thanks to...
  40. cookiemnstr510510

    MATLAB logical functions and selection structures

    Hello All, I have a question regarding a MATLAB homework problem. I am learning about logical functions and selection structures. Here is the question: The height of a rocket (in meters) can be represented by the following equation: height=(2.13*t^2)-(0.0013*t^4)+((0.000034*t^(4.751)) create a...
  41. nineteen

    What tutorial for Resonance structures?

    Hello everybody, I am stuck with drawing resonance structures for different types of compounds. Do you know any tutorials or any methods to master drawing resonance structures? If yes, please be kind enough to drop some links and statements below. Thank you very much in advance.
  42. nineteen

    Why do we have to memorize Lewis structures of ....

    Why do we have to memorize the structures of all the nitrogen oxides? Isn't there any way to understand about the Lewis structures of all the nitrogen oxides and their weird ways of making bonds?
  43. fresh_42

    Insights Lie Algebras: A Walkthrough The Structures - Comments

    Greg Bernhardt submitted a new blog post Lie Algebras: A Walkthrough The Structures Continue reading the Original Blog Post.
  44. QuantumQuest

    Insights Intro to Data Structures for Programming - Comments

    Greg Bernhardt submitted a new blog post Intro to Data Structures for Programming Continue reading the Original Blog Post.
  45. Math Amateur

    MHB Smooth Structures .... Dundas, Example 2.2.6 .... ....

    I am reading Bjorn Ian Dundas' book: "A Short Course in Differential Topology" ... I am focused on Chapter 2: Smooth Manifolds ... ... I need help in order to fully understand Example 2.2.6 ... ... Example 2.2.6 reads as follows: My questions are as follows: Question 1 In the above text...
  46. N

    H2F+ or CH3SH2+ which is more acidic by looking at the structures?

    Homework Statement Which molecule is more acidic H2F+ or CH3SH2+ Homework Equations None The Attempt at a Solution H2F is more acidic as the answer. However, I was told in class that there were several factors affecting acidity, with some having more weight such as resonance>atomic radius>...
  47. Jason K

    Writing: Input Wanted Submerged Structures in an Ocean World

    Suppose that there exists a rotating water planet, i.e. a planet with a fairly deep ocean, which contains a large structure of a particular geometry submerged within the ocean. If this structure was assembled within the ocean will it, once it reaches a steady state, rotate at the same rate as...
  48. Vigardo

    Wind loads for circular cross-section lattice structures?

    Dear experts, How should I compute the wind loads for a Shukhow tower, i.e. a circular cross-section steel lattice structure? The structural members should be rectangular or circular. I´ve been checking EUROCODEs EN 1991-1-4 (2005) and EN 1993-3-1 (2006) without success. Is there any other...
  49. G

    A Diffraction on periodic Structures

    I am trying to understand diffraction on periodic structured in solid state physics.Q is the source of the spherical wave. R the vector to the object and R+r the vector to the scattering centre P, which gives us a another spherical wave. All spherical waves are considered as plane waves due to...
  50. H

    Engineering Suggest a good book on the theory of elasticity & structures

    I am 2nd year physics undergrad. Just want to study a bit about materials in my free time. I have no idea about engineering books. Please suggest some good books. Thanks.