CIRCUITSS

  

Copyright © Philip M. Parker, INSEAD. Terms of Use.

CIRCUITSS

Specialty Definition: Circuit (airfield)

(From Wikipedia, the free Encyclopedia)

At an airfield, the circuit is a conventional standard path for coordinating air traffic that is taking off and landing, as opposed to a practice of so-called "straight in approaches" and "direct climb outs". It is usually employed at small general aviation (GA) airfields, though it is also used at military airfields. Most large airports don't use this system as such, unless they have GA activity as well as commercial flights. However, a circuit of sorts is used at airports in some cases, such as when an aircraft is required to go around.

An aircraft taking off will usually be expected to follow the circuit in use, and one arriving at the field to land will be expected to join the circuit in an orderly fashion before landing. This is often accomplished using an overhead join, or by entering on any of the circuit legs, traffic permitting. Aircraft are expected to join and leave the circuit in an orderly and safe manner. Sometimes this will be at the discretion of the pilot, at other times he will be directed by air traffic control. Airfield operators will set up circuits according to the runway in use, the local conventions for noise abatement or other ground features, and the current usage of the airfield. While many operate a completely standard pattern, in many cases it will be modified according to need.

Circuits can be defined as left or right hand, according to which way the turns in the circuit lie. Circuits are typically rectangular in basic shape, and include the runway along one long side of the rectangle. Each leg of the circuit has a particular name:

Military airfields often dispense with the crosswind and base legs, but rather fly these as circular arcs directly joining the upwind and downwind sections.

An airfield will define a circuit height, that is, a nominal altitude above the field (see QFE) that pilots are required to fly at while in the circuit. A typical circuit height would be 1000ft.

The use of a circuit at airfields is for safety - rather than have aircraft flying around the field in a haphazard fashion, by using a circuit pilots will know where to expect other air traffic from, and be able to see it and avoid it. GA pilots flying under VFR conditions will not be separated by air traffic control, and so the circuit is a vital way to keep things orderly.

A pilot undergoing training will often fly many, many circuits one after another. Usually, each landing is followed immediately by a take off and further circuit. This is called a touch and go.

Americans usually refer to the circuit as the traffic pattern or simply pattern. Similarly, circuit height would be referred to as pattern altitude.

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Circuit (airfield)."

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Circuit (political division)

(From Wikipedia, the free Encyclopedia)

A circuit is an appealate judicial district among the courts of many nations. The name comes from an era in which justices would ride within a area hearing cases.

Circuit (道 ; Chinese: dào; Japanese: dō) was a Chinese political division, and is a Japanese one. In Korea, the same word 道 (도; Do) is translated as "Province."

China

It originated in China in 627, when Emperor Taizong (唐太宗) subdivided China into ten circuits. Emperor Xuanzong (玄宗) further added 5. It was abolished as the highest administrative divisions when the Qing Empire collapsed in 1911. However, circuits still existed as high-level, though not top-level, divisions of the Republic of China, such as Qionyai Circuit (now Hainan Province). In 1928, all circuits were replaced with committees or just completely abandoned.

Circuits were the highest of the three-tier system (三級制), the next two are prefectures (州) and districts (縣). They are simultaneously inspection areas (監察區 jian1 cha2 qu1).

Japan

The newest and only remaining Japanese circuit is Hokkaido "North Sea Circuit", which has the equivalent status as a prefecture. The seven defunct circuits spread all over the other three islands:

(For the mountain south-north reference with in and yo, see Yin Yang)

See also Old provinces of Japan

Korea

Since the late 10th century, the Do ("Province") has been the primary administrative division in Korea. See Provinces of Korea for details.

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Circuit (political division)."

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Electrical network

(From Wikipedia, the free Encyclopedia)

An electrical network or electrical circuit is an interconnection of analog electrical elements such as resistors, inductors, capacitors, diodes, switches and transistors. It can be as small as an integrated circuit on a silicon chip, or as large as an electricity distribution network.

A circuit is a network that has a closed loop i.e. a return path. A network is a connection of 2 or more simple circuit elements, and may not be a circuit.

The goal when designing electrical networks for signal processing is to apply a predefined operation on potential differences (measured in volts) or currentss (measured in amperes). Typical functions for these electrical networks are amplification, oscillation and analog linear algorithmic operations such as addition, subtraction, multiplication, division, differentiation and integration.

In the case of power distribution networks, engineers design the circuit to transport the energy as efficiently as possible while at the same time taking into account economic factors, network safety and redundancy. These networks use components such as power lines, cables, circuit breakers, switches and transformers.

To design any electrical circuits, electrical engineers need to be able to predict the voltages and currents in the circuit. Linear circuits can be analysed to a certain extent by hand because complex number theory gives engineers the ability to treat all linear elements using a single mathematical representation.

A number of electrical laws apply to all electrical networks. These include

Other more complex laws may be needed if the network contains nonlinear or reactive components. Non-linear self-regenerative hetrodyning systems can be approximated. Applying these laws results in a set of simultaneous equations that can be solved either by hand or by a computer.

Network simulation software

In more complex circuits, engineers need to turn to circuit simulation software. SPICE is the most famous of these.

Linearization around operating point

When faced with a new circuit, the software first tries to find a steady state solution. This is a solution where all nodes conform to Kirchhoff's Current Law and the voltages across and through each element of the circuit conform to the voltage/current equations governing that element.

Once the steady state solution is found, the operating points of each element in the circuit are known. For a small signal analysis, every non-linear element can be linearized around its operation point to obtain the small-signal estimate of the voltages and currents. This is an application of Ohm's Law. The resulting linear circuit matrix can be solved with Gauss-Jordan elimination.

Piece-wise linear approximation

This type of simulator uses piece-wise linear approximations of the equations governing the elements of a circuit. This approximation comes down to splitting the circuit into two parts: a completely linear network with a number of terminals that connect to ideal diodes. Every time a diode switches from on to off or vice versa, the linear network is configured differently. Increasing the accuracy of the simulation can be achieved by adding more detail to the approximation of the equations, this will increase the running time of the simulation. This flexibility allows an engineer to make a trade-off between simulation time and the precision of the results, something that is not easily done with the previous simulation technique.

See also

External link

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Electrical network."

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INDEX

1. Bibliography


  

Copyright © Philip M. Parker, INSEAD. Terms of Use.