アドミッタンス、入場許可

PrepTutorEJDIC

(場所への)入場,入場許可《+『to』+『名』》

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2018/02/09 05:41:26」(JST)

wiki en

In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow. It is defined as the reciprocal of impedance. The SI unit of admittance is the siemens (symbol S); the older, synonymous unit is mho, and its symbol is ℧ (an upside-down uppercase omega Ω). Oliver Heaviside coined the term admittance in December 1887.^[1]

Admittance is defined as

Y\equiv {\frac {1}{Z}}\,

where

Y is the admittance, measured in siemens

Z is the impedance, measured in ohms

Resistance is a measure of the opposition of a circuit to the flow of a steady current, while impedance takes into account not only the resistance but also dynamic effects (known as reactance). Likewise, admittance is not only a measure of the ease with which a steady current can flow, but also the dynamic effects of the material's susceptance to polarization:

Y=G+jB\,

where

$Y$ is the admittance, measured in siemens.
$G$ is the conductance, measured in siemens.
$B$ is the susceptance, measured in siemens.
$j^{2}=-1$

Conversion from impedance to admittance

Parts of this article or section rely on the reader's knowledge of the complex impedance representation of capacitors and inductors and on knowledge of the frequency domain representation of signals.

The impedance, Z, is composed of real and imaginary parts,

Z=R+jX\,

where

R is the resistance, measured in ohms
X is the reactance, measured in ohms

Y=Z^{-1}={\frac {1}{R+jX}}=\left({\frac {1}{R^{2}+X^{2}}}\right)\left(R-jX\right)

Admittance, just like impedance, is a complex number, made up of a real part (the conductance, G), and an imaginary part (the susceptance, B), thus:

Y=G+jB\,\!

where G (conductance) and B (susceptance) are given by:

{\begin{aligned}G&=\Re (Y)={\frac {R}{R^{2}+X^{2}}}\\B&=\Im (Y)=-{\frac {X}{R^{2}+X^{2}}}\end{aligned}}

The magnitude and phase of the admittance are given by:

{\begin{aligned}\left|Y\right|&={\sqrt {G^{2}+B^{2}}}={\frac {1}{\sqrt {R^{2}+X^{2}}}}\\\angle Y&=\arctan \left({\frac {B}{G}}\right)=\arctan \left(-{\frac {X}{R}}\right)\end{aligned}}

where

G is the conductance, measured in siemens
B is the susceptance, also measured in siemens

Note that (as shown above) the signs of reactances become reversed in the admittance domain; i.e. capacitive susceptance is positive and inductive susceptance is negative.

Shunt Admittance in Electrical Power Systems Modeling

In the context of electrical modeling of transformers and transmission lines, shunt components that provide paths of least resistance in certain models are generally specified in terms of their admittance. Each side of most transformer models contains shunt components which model magnetizing current and core losses. These shunt components can be referenced to the primary or secondary side. For simplified transformer analysis, admittance from shunt elements can be neglected. When shunt components have non-negligible effects on system operation, the shunt admittance must be considered. In the diagram below, all shunt admittances are referred to the primary side. The real and imaginary components of the shunt admittance, conductance and susceptance, are represented by Gc and B, respectively.

^[2]

Transmission lines can span hundreds of kilometers, over which the line’s capacitance can affect voltage levels. For short length transmission line analysis, which applies to lines shorter than 80 kilometers, this capacitance can be ignored and shunt components are not necessary in the model. Lines between 80 and about 250 kilometers, generally considered to be in the medium-line category, contain a shunt admittance governed by

$Y=yl=j\omega Cl$

where

Y – total shunt admittance

y – shunt admittance per unit length

l – length of line

C – capacitance of line

^[3]

^[4]

References

^ Ushida, Jun; Tokushima, Masatoshi; Shirane, Masayuki; Gomyo, Akiko; Yamada, Hirohito (2003). "Immittance matching for multidimensional open-system photonic crystals". Physical Review B. 68 (15). arXiv:cond-mat/0306260 . Bibcode:2003PhRvB..68o5115U. doi:10.1103/PhysRevB.68.155115.
^ Grainger, John J.; Stevenson, William D. (1994). Power System Analysis. New York: McGraw-Hill.
^ J. Glover, M. Sarma, and T. Overbye, Power System Analysis and Design, Fifth Edition, Cengage Learning, Connecticut, 2012, ISBN 978-1-111-42577-7, Chapter 5 Transmission Lines: Steady-State Operation
^ Ghosh, Arindam. chapter_2/2_7.html "Equivalent- π Representation of a Long Line" Check |url= value (help).

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 裂肛のマネージメントのための側方内肛門括約筋切開術 lateral internal sphincterotomy for management of an anal fissure

English Journal

ICU admittance by a rapid response team versus conventional admittance, characteristics, and outcome*.

Jäderling G, Bell M, Martling CR, Ekbom A, Bottai M, Konrad D.Source1 Department of Physiology and Pharmacology, Section for Anesthesiology and Intensive Care, Karolinska Institutet, Stockholm, Sweden. 2 Department of Medicine, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden. 3 Department of Environmental Medicine, Unit of Biostatistics, Karolinska Institutet, Stockholm, Sweden.
Critical care medicine.Crit Care Med.2013 Mar;41(3):725-31. doi: 10.1097/CCM.0b013e3182711b94.
OBJECTIVE: : To evaluate characteristics and outcome of ICU patients admitted from general wards based on mode of admittance, via a rapid response team or conventional contact.DESIGN: : Observational prospective study.SETTING: : General ICU of a university hospital.PATIENTS: : A total of 694 admissi
PMID 23318488

Identification of conductive hearing loss in young infants using tympanometry and wideband reflectance.

Prieve BA, Werff KR, Preston JL, Georgantas L.Source1Department of Communication Sciences and Disorders, Syracuse University, Communication Sciences and Disorders, Syracuse, New York, USA; 2Department of Communication Disorders, Southern Connecticut State University, New Haven, Connecticut, USA; 3Department of Audiology, Cleveland Clinic, Head and Neck Institute, Cleveland, Ohio, USA.
Ear and hearing.Ear Hear.2013 Mar;34(2):168-78. doi: 10.1097/AUD.0b013e31826fe611.
OBJECTIVE: : The goal of the study was to evaluate the effectiveness of tympanometry and wideband reflectance (WBR) in detecting conductive hearing loss (CHL) in young infants.METHODS: : Type of hearing loss was determined using auditory brainstem response using air- and bone-conducted tone bursts i
PMID 23263407

Working with denial in convicted sexual offenders: a qualitative analysis of treatment professionals' views and experiences and their implications for practice.

Blagden N, Winder B, Gregson M, Thorne K.Source1Nottingham Trent University, UK.
International journal of offender therapy and comparative criminology.Int J Offender Ther Comp Criminol.2013 Mar;57(3):332-56. doi: 10.1177/0306624X11432301. Epub 2011 Dec 19.
Denial in sexual offenders represents the first barrier to successful treatment a clinician is likely to face. However, there is currently no research focusing on the experiences of treatment professionals who treat and manage deniers. This study aimed to bridge this research gap and to gain an insi
PMID 22186882