Structure

Source: Wikipedia, the free encyclopedia.
For other uses, see Structure (disambiguation).
The structure of a DNA molecule is essential to its function.

A structure is an arrangement and organization of interrelated elements in a material object or

links, or a lattice
featuring connections between components that are neighbors in space.

Load-bearing

Sami
food storage structure
Gothic quadripartite cross-ribbed vaults of the Saint-Séverin church in Paris

architectural structures
, civil engineering structures and mechanical structures.

The effects of loads on physical structures are determined through structural analysis, which is one of the tasks of structural engineering. The structural elements can be classified as one-dimensional (ropes, struts, beams, arches), two-dimensional (membranes, plates, slab, shells, vaults), or three-dimensional (solid masses).[2]: 2  Three-dimensional elements were the main option available to early structures such as Chichen Itza. A one-dimensional element has one dimension much larger than the other two, so the other dimensions can be neglected in calculations; however, the ratio of the smaller dimensions and the composition can determine the flexural and compressive stiffness of the element. Two-dimensional elements with a thin third dimension have little of either but can resist biaxial traction.[2]: 2–3 

The structure elements are combined in structural systems. The majority of everyday load-bearing structures are section-active structures like frames, which are primarily composed of one-dimensional (bending) structures. Other types are Vector-active structures such as trusses, surface-active structures such as shells and folded plates, form-active structures such as cable or membrane structures, and hybrid structures.[3]: 134–136 

Load-bearing biological structures such as bones, teeth, shells, and tendons derive their strength from a multilevel hierarchy of structures employing biominerals and proteins, at the bottom of which are collagen fibrils.[4]

Biological

organisms.[5]

In

organs, and organisms
.

In another context, structure can also observed in

hydrogen bonding. The two basic types are the α-helix and the β-pleated sheet. The tertiary structure is a back and forth bending of the polypeptide chain, and the quaternary structure is the way that tertiary units come together and interact.[7] Structural biology is concerned with biomolecular structure of macromolecules.[6]

Chemical

Main article: Chemical structure
A skeletal formula for dopamine

Chemical structure refers to both molecular geometry and electronic structure. The structure can be represented by a variety of diagrams called structural formulas. Lewis structures use a dot notation to represent the valence electrons for an atom; these are the electrons that determine the role of the atom in chemical reactions.[8]: 71–72  Bonds between atoms can be represented by lines with one line for each pair of electrons that is shared. In a simplified version of such a diagram, called a skeletal formula, only carbon-carbon bonds and functional groups are shown.[9]

Atoms in a crystal have a structure that involves repetition of a basic unit called a unit cell. The atoms can be modeled as points on a lattice, and one can explore the effect of symmetry operations that include rotations about a point, reflections about a symmetry planes, and translations (movements of all the points by the same amount). Each crystal has a finite group, called the space group, of such operations that map it onto itself; there are 230 possible space groups.[10]: 125–126  By Neumann's law, the symmetry of a crystal determines what physical properties, including piezoelectricity and ferromagnetism, the crystal can have.[11]: 34–36, 91–92, 168–169 

Mathematical

Main article: Mathematical structure

Musical

See also: Musical form
A motif from the Preludes by Chopin, Op. 28 no.6, bars 1–3

A large part of numerical analysis involves identifying and interpreting the structure of musical works. Structure can be found at the level of part of a work, the entire work, or a group of works.[12] Elements of music such as pitch, duration and timbre combine into small elements like motifs and phrases, and these in turn combine in larger structures. Not all music (for example, that of John Cage) has a hierarchical organization, but hierarchy makes it easier for a listener to understand and remember the music.[13]: 80 

In analogy to

cadence in the middle and a full cadence at the end providing punctuation.[16]: 38–39  On a larger scale are single-movement forms such as the sonata form and the contrapuntal form, and multi-movement forms such as the symphony.[13]

Social

Main article: Social structure

A social structure is a pattern of relationships. They are social

ethnicity
, customs, etc. that seem to limit or influence individual opportunities.

Data

Main article: Data structure
In a singly linked list, each element has a data value and a pointer to the next element.

In

array has an index that can be used for immediate access to any data item (some programming languages require array size to be initialized). A linked list can be reorganized, grown or shrunk, but its elements must be accessed with a pointer that links them together in a particular order.[19]: 156  Out of these any number of other data structures can be created such as stacks, queues, trees and hash tables.[20][21]

In solving a problem, a data structure is generally an integral part of the algorithm.[22]: 5  In modern programming style, algorithms and data structures are encapsulated together in an abstract data type.[22]: ix 

Software

Main article: Software architecture

Software architecture is the specific choices made between possible alternatives within a framework. For example, a framework might require a database and the architecture would specify the type and manufacturer of the database. The

flow logic and design.[24] Structural elements reflect the requirements of the application: for example, if the system requires a high fault tolerance, then a redundant structure is needed so that if a component fails it has backups.[25] A high redundancy is an essential part of the design of several systems in the Space Shuttle.[26]

Logical

As a branch of philosophy, logic is concerned with distinguishing good arguments from poor ones. A chief concern is with the structure of arguments.[27] An argument consists of one or more premises from which a conclusion is inferred.[28] The steps in this inference can be expressed in a formal way and their structure analyzed. Two basic types of inference are deduction and induction. In a valid deduction, the conclusion necessarily follows from the premises, regardless of whether they are true or not. An invalid deduction contains some error in the analysis. An inductive argument claims that if the premises are true, the conclusion is likely.[28]

See also

References

  1. ^ "structure, n.". Oxford English Dictionary (Online ed.). Retrieved 1 October 2015.
  2. ^
    ISBN 9780203474952
    .
  3. ISBN 9783034614702
    .
  4. PMID 20810437
    .
  5. ^
    ISBN 978-0134093413
    .
  6. ^
    ISBN 9780080521848
    .
  7. ISBN 9780716798569
    .
  8. ISBN 9780935702613
    .
  9. ISBN 9780174482765
    .
  10. ISBN 9780030839931
    .
  11. ISBN 9780191523403
    .
  12. ^ Bent, Ian D.; Pople, Anthony. "Analysis". Grove Music Online. Oxford Music Online. Oxford University Press. Retrieved October 5, 2015.
  13. ^
    ISBN 9780520022164
    .
  14. ^ "Sentence". Grove Music Online. Oxford Music Online. Oxford University Press. Retrieved October 5, 2015.
  15. ^ "Phrase". Grove Music Online. Oxford Music Online. Oxford University Press. Retrieved October 5, 2015.
  16. ISBN 9781457400940
    .
  17. OCLC 43708597
    .
  18. Dictionary of Algorithms and Data Structures (Online ed.). National Institute of Standards and Technology
    . Retrieved 1 October 2015.
  19. ISBN 9780132762564
    .
  20. ISBN 978-0262033848
    .
  21. ISBN 9781420035179
    .
  22. ^
    ISBN 9781848000704
    .
  23. ISBN 9783642191763
    .
  24. ISBN 978-3540465041
    .
  25. ISBN 9783642395123
    .
  26. ^ "Computers in the Space Shuttle Avionics System". Computers in Spaceflight: The NASA Experience. Retrieved 2 October 2015.
  27. ^ "The Structure of Arguments". Philosophy 103: Introduction to Logic. philosophy.lander.edu. Retrieved 4 October 2015.
  28. ^ a b Kemerling, Garth. "Arguments and Inference". The Philosophy Pages. Retrieved 4 October 2015.

Further reading

External links
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