MAGNETOHYDRODYNAMIC (MHD) GENERATION

In conventional power generation, fuel such as oil or coal is burned. The burning  fuel heats boilers to produce steam. The steam is used to drive turbo-alternators. The MHD process generates electricity without requiring a boiler or a turbine.

                MHD generation works on the principle that when a conductor cuts a magnetic field, a current flows through the conductor. In MHD generation the conductor is an ionized gas. Small amounts of metal are added to the gas to improve its conductivity. This is called seeding the gas. The seeded gas is the pumped at a high temperature and pressure through a strong magnetic field. The electrons in the gas are collected at an electrode. This movement of electrons constitutes  a current flow.

                Two methods of MHD generation can be used : the open cycle and the closed cycle. In the open cycle method the hot gas is discharged. In the closed cycle method it is recirculated.

                The open cycle method uses gas from burning coal or oil. The gas is seeded  and then passed through a magnetic field to generate current. The seeding elements are recovered and the gas can then be used to drive a turbine before being allowed to escape.

              The closed cycle method uses an inert gas, such as helium, which is heated indirectly. The gas is circulated continually through the MHD generator.

                MHD generation is still in its early stages but already an efficiency rate of 60% has been reached. This compares with a maximum of 40% from conventional power station.

CIRCUIT ELEMENTS. (Elemen-elemen Sirkuit)

Current moves from a point of high potential energy to one of low potential. It can only do so if there is path for it to follow. All circuit contain four elements : a source, a load, a transmission system and a control.

(arus bergerak dari ujung energi potensial tinggi ke potensial yang rendah . Ia hanya bisa berbuat demikian jika ada jalan untuk mengikuti. Semua sirkuit berisi empat elemen : sumber, beban, sistem transmisi dan  kontrol.)

The source provides the electromotive force. This establishes the difference in potential which makes current flow possible.  The source can be any device which supplies electrical energy. For example, it may be a generator or a battery.

(Sumber memberikan tegangan gerak elektrik. Ini membuat perbedaan dalam potensi yang membuat aliran arus memungkinkan. Sumber dapat menjadi alat apapun yang menyediakan tenaga elektris. Sebagai contoh, mungkin saja suatu pembangkit atau baterai.)

The load converts the electrical energy from the source into some other form of energy. For instance, a lamp changes electrical energy into light and heat. The load can be any electrical device.

(Beban mengubah tenaga elektris dari sumber ke dalam beberapa bentuk energi lain. Sebagai contoh, lampu berubah tenaga elektris ke dalam menerangi dan panas. Beban dapat menjadi apa pun alat listrik.)

The transmission system conduct the current round the circuit.  Any conductor can be part of a transmission system. Most system consist of wires. It is often possible, however, for the metal frame of a unit to be one section of its transmission system. For Example, the metal chassis of many electrical devices are used to conduct current. Similarly the body of a car is part of its electrical transmission system.

(Sistem transmisi mengelilingi arus pada rangkaian. Kondektur apapun dapat menjadi bagian dari sistem transmisi. Kebanyakan sistem terdiri dari kabel-kabel. Itu mungkin kebanyakan, akan tetapi, untuk bingkai logam satu bagian menjadi satu bagian sistem transmisinya. Sebagai contoh, casis logam yang banyak alat-alat listriknya digunakan membuat arus. Demikian pula badan sebuah mobil adalah bagian sistem transmisi listriknya.)

The control regulates the current flow in the circuit. It may control the current by limiting it, as does a rheostat, or by interrupting it, as does a switch.

(Kontrol mengatur aliran arus dalam sirkuit. Ia dapat mengontrol arus dengan membatasinya, sama seperti reostat, atau dengan menyela nya, sama seperti sebuah saklar.

Study figure 1. In this simple flashlight circuit, the source comprises three 15 V cells in series. The load is a 0.3 W bulb. Part of the transmission system is the metal body of the flashlight, and the control is a sliding switch.

(Belajar figur 1. Dalam rangkaian lampu senter sederhana ini, sumber terdiri dari tiga sel-sel 1.5 V dalam seri. Bebannya 0.3 W pentolan Bagian sistem transmisi yaitu badan logam lampu senter, dan kontrolnya saklar sorong.)

Compare figure 2. The function of this circuit is to operate a television camera aboard a space satellite. Here the source is a battery of solar cells. A solar cell is  a electrical cell which converts sunlight into electrical energy. The load is the television camera. The transmission system is the connecting wires. The control is a relay actuated by transmissions from ground control. Although the function of this circuit is much more complex than that of the flashlight, it too consists of the four basic elements.

(Membandingkan figur 2. Fungsi sirkuit ini adalah untuk menjalankan kamera televisi naik  ke satelit. Di sini sumbernya baterai sel-sel surya. sel matahari adalah sebuah sel listrik yang mana mengubah cahaya ke dalam tenaga elektris. Bebannya  kamera televisi. Sistem transmisinya menghubungkan kabel-kabel. Kontrolnya  digerakkan oleh transmisi-transmisi dari control tanah. Meskipun fungsi sirkuit ini jauh lebih kompleks daripada dari lampu senter, ia juga terdiri dari empat elemen dasar.)

Traffic Jam

Traffic jam in big cities in Indonesia especially in Jakarta has been very worrying. Traffic jam is a situation that the traffic/way is broken off. It caused by the large number of over capacity of the road.

Traffic  jam can occur for several reasons.

1.       Amount of vehicles through the road is over the capacity of the road

2.       The many puddles (hole in the road)on some streets.

3.       The users of road are violating the traffic jam

Negative impacts

1.       Lossing time

2.       Wasting Energy

3.       Increasing air pollution

4.       Improving stress of the road users

5.       Disturbing way of emergency vehicles

Solving the problem of traffic jam (Conclution)

1.       Increasing the capacity of road

2.       Changing the circulation of traffic into one way

3.       Reducing the public transportation production

4.       Limits using personal cars