In electronics, impedance
matching is the practice of designing the input impedance of an electrical
load (or the output impedance of its corresponding signal source) to maximize
the power transfer or minimize reflections from the load.
Source and load circuit impedance
In the case of a complex
source impedance ZS and load impedance ZL,
maximum power transfer is obtained when
where * indicates the complex
conjugate. Minimum reflection is obtained when
The concept of impedance
matching was originally developed for electrical engineering, but can be
applied to any other field where a form of energy (not necessarily electrical)
is transferred between a source and a load. An alternative to impedance matching
is impedance bridging, where the load impedance is chosen to be much larger
than the source impedance and maximizing voltage transfer (rather than power)
is the goal.
AC Current flow
in 120/240 V AC single phase three or four wire systems is frequently
misunderstood. This technical brief goes through a step by step process of
adding one load at a time to a 120/240 V AC system and looking at the resulting
current flows.
There is an
assumed understanding of basic DC theory, Ohms Law (V=IR), the Power Law (P=VI)
and Kirchhoff’s Voltage and Current Laws.
1.The sum of the voltage rises equals the sum of
the voltage drops around any closed loop.
2.The sum of the currents entering a junction
equals the sum of the currents leaving the junction.
Auteur
:Bari M. Logan, Patricia
Reynolds, Ralph T. Hutchings Edition : Mosby
Pages:294 Format: pdf Language:English
This popular resource uses a unique, oversized format to clearly
and thoroughly demonstrate the anatomy of the head and neck. Outstanding
dissections and illustrations, osteology, radiography, and surface anatomy
photographs capture the full range of anatomical structures. Brief textual
explanations accompany every figure, facilitating understanding and study. This
3rd Edition features many new and improved images as well as updates to reflect
the latest terminology.
Auteur : Pierre Ricaud Edition : H.Vial Pages:217 Format: pdf Language:Français
Sommaire: Géométrie généralités
Le point
La droite (horizontale, verticale, répartitions)
Les parallèles (fabrication d’un trusquin de menuisier)
Les perpendiculaires (tracés, fabrication d’équerres en bois)
Les angles (méthodes de traçage, reporter un angle, ouverture des porte)
Les triangles
Les quadrilatères : le carré
Les quadrilatères : le losange
Les quadrilatères : le rectangle
Les quadrilatères : le trapèze
Le parallélogramme
Géométrie et perspective