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E-book Hydraulics in Civil Engineering : A Course with Experiments and Open-Source-Codes

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Penilaian

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According to the equations of the general theory of relativity, the universe is either ex-panding or contracting [17]. In order to circumvent the unthinkable, Einstein introduceda factor to keep the size constant. Some 20 years later, however, Hubble, who gave hisname to the telescope, discovered that the universe is actually expanding. He did thisby proving that the color spectrums of far stars change as a result of their motion. Thisfrequency shift, also referred to as the Doppler effect, occurs if a source moves relative toa receiver (as in the case of a police car siren). This evidence confirmed that a continuousexpansion must take place. The Big Bang theory was born, and it is still the most prob-able scenario of the origin of the universe. The age of our universe could be quantified as13.8 billion years. We’ll never know what, and indeed if, anything came before that.Water is the material source of all things. We often come across this quote by Thalesof Miletus (624 to 546 BCE). The considerations that led to it will remain a secret de-spite countless interpretations. However, when van Helmont planted a young tree into apot 2,000 years later for a scientific experiment and only watered it, he saw a consider-able increase in weight five years later, thus confirming Thales’ thesis [2]. At that time,nothing was known about the conversion of light energy to chemical energy, the so-calledphenomenon known as photosynthesis.It wasn’t until the 18th century that the Greek theory of the four basic elements (fire,water, earth, air) led to the chemical elements we know today as a result of researchconducted by Lavoisier (1743 to 1794). He performed an experiment to demonstrate thatburning “two parts inflammable air and one part life air” produces water [2]. He presentedthe results on June 25, 1783, at the Acad ?emie des Sciences. This not only revealed thechemical origin of water but also established stoichiometry, which then contributed to thewell-known periodic table of the elements. At that time, oxygen – from the Greek “oxys”(acid) and“gen”(create), i. e. acid-former – was a known element, and it was Lavoisier whointroduced hydrog`ene (hydrogen), the water-former. Though it is not possible to deducethe generation of the simplest element, hydrogen, with only one proton and one electron,itisknownthatitcanbecreatedatatemperatureof3700?Cby the combination of theelementary particles. The other heavier elements such as oxygen stemmed from nuclearfusion of the hydrogen atoms during the birth of stars, as Rutherford proved in 1917.Thereby, the creation of water is certainly obvious: It is the combination of the twomost-prevalent reactive elements in the universe – hydrogen and oxygen – that makes life possible: H2O. One water molecule comprises two hydrogen atoms and one oxygen atom.The oxygen atom “borrows” one electron from each of the two hydrogen atoms in order toassume a lower energy state – this is the atom’s mission. The hydrogen, too, benefits fromthis liaison because the oxygen also shares one of its desired electrons with each of thehydrogen atoms. Two other electron pairs of the oxygen, so-called valence electrons, aremoved to the opposite sides such that the molecule spans a tetrahedron (derived from theGreek words for “four” and “surface”). The oxygen now subjects the shared electron pairsto a little more stress such that the two hydrogen atoms form slightly positively chargedpoints and the valence electrons slightly negatively charged corners. This results in whatare known as hydrogen bridge bonds, wherein the molecules unite with approximatelyone tenth of the force of the atomic bonds as the positively charged hydrogen corners areattracted to the negatively charged corners of the oxygen atoms of other molecules. Thesehydrogen bridge bonds, which are broken and re-formed repeatedly, give water many ofits characteristic properties. They are also responsible for the so-called density anomaly,e. g. they are the reason why ice floats. Water may assume three different phases, whichare primarily dependent on two state variables: the temperature and the pressure (pleasescroll to Figure 3.3 on page 31).

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Ketersediaan

Informasi Detail

Judul Seri

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No. Panggil

627 RAP h

Penerbit

Switzerland : Springer Nature., 2024

Deskripsi Fisik

385 hlm

Bahasa

English

ISBN/ISSN

9783031548604

Klasifikasi

627

Tipe Isi

text

Tipe Media

computer

Tipe Pembawa

online resource

Edisi

-

Subjek

Hydraulic Engineering

Info Detail Spesifik

-

Pernyataan Tanggungjawab

-

Versi lain/terkait

Lampiran Berkas

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