VLSI highly integrated circuits

VLSI Very Large Scale Integrated Circuit is a combination of a large number of transistors to a single integrated circuit chip, which is larger than the degree of LSI integration. The number of transistors integrated different in different standards. Starting in the 1970s, with the development of complex semiconductor and communication technology, integrated research, development has gradually expanded. The computer control core microprocessor is the most typical examples of ultra large scale integrated circuit, VLSI Design, especially digital integrated circuits, electronic design automation usually the way, has become an important branch of computer engineering one.

IC according to the level of integration can be divided into small-scale integrated circuits, the size of integrated circuits, LSI, VLSI, VLSI and huge integrated circuits.

Small-scale integrated circuit in 1960 appeared on a silicon wafer containing 10-100 1-10 element or logic gates. Such as logic gates and flip-flops and so on. If small-scale digital integrated circuits (SSI) design combinational logic circuit, it is the gate as the basic unit of the circuit, so simplifying logic function of the number of gates should be used at least, and also the number of inputs of the gate at least.

Modulation

Modulation is a cyclical one or more carriers want to transfer the mixed signal technology, commonly used in radio wave propagation and communications, the use of all aspects of data communication telephone lines and the like. Depending on the modulation signal can be divided into several bits modulation and analog modulation, these different modulation, in a different way, the signal and the carrier synthesis technology. The reverse process is called modulation demodulation for the solution of the original signal.

Significance of modulation

Spectrum signals can be move to any position, thus contributing to the transmitted signal, and the spectrum resources are fully utilized. For example, the antenna size is one tenth or larger signal, the signal can be effectively radiated.  For speech signals, corresponding antenna size to be in the tens of kilometers or more, it is virtually impossible to achieve. This requires that the signal spectrum modulation process move to a higher frequency range. If you do not put the signal directly modulated radiation out, then the frequency of the radio signal emitted by each will be the same. Modulation of the substance is to make the same frequency range signals are relying on a different carrier frequency, the receiver can be isolated frequency signal required, will not interfere with each other. This is the basis to achieve multiplexed on the same channel.

Universal Mobile Telecommunications System

Universal Mobile Telecommunications System, called UMTS (Universal Mobile Telecommunications System), UMTS as a complete 3G mobile communication technology standards, UMTS is not limited to define an air interface. In addition to WCDMA air interface technology as the preferred continuous improvement get outside, UMTS also have been introduced in the TD-SCDMA and HSDPA technology.

One kind of third-generation (3G) mobile phone technology. It uses WCDMA as the underlying standard by the 3GPP, and represents the European response to ITUIMT-2000 for 3G Cellular radio systems. UMTS is also sometimes called 3GSM, emphasizing the combination of 3G technology and the GSM standard follow-up criteria. UMTS packet switching system is being evolved by the GPRS system, so the architecture of the system is quite similar.

UMTS supports transfer rates of 1920 kbps (not often seen 2Mbps), but typically the highest rate of 384Kbps in reality only about high-load systems. Even so the data rate has been higher than the GSM error correcting data channel 14.4kbps or more consisting of 14.4 kbps HSCSD channel can really achieve price acceptable mobile WWW access and MMS. UMTS premise implementation is now widely used in GSM mobile telephone system, belonging to 2G technology. There is also a way evolution from 2G GPRS called. (Can be seen as 2.5G) GPRS support better data rate (theoretical maximum 140.8kbps, can actually achieve close 56Kbps), better than the connection-oriented data encapsulation. GPRS has been deployed in many GSM networks.

China Unicom's UMTS network upgrade to HSDPA, sometimes also called 3.5G. It can make a downlink transmission speed of 10Mbps.

UMTS has emphasized the possibility in the market for mobile video conference call to achieve, despite the fact that there are many promising service has not been tested to verify.
Other possible uses for UMTS music downloads and video telephony.

Lathe

Lathe is the main vehicles for rotating the workpiece knife turning machine.
In 1797, the British created the modern mechanical inventor Maudslay lathe turret with a screw drive, and in 1800 the use of change gears, you can change the feed rate and the processing thread pitch. In 1817, another Englishman Roberts uses four wheels and rear wheel mechanism to change the spindle speed.

In order to improve the degree of mechanization and automation, in 1845, the US Fitch invention turret lathe.

Early 20th century by a single motor-driven lathe with a gear transmission.
After World War I, due to the need of arms, vehicles and other machinery industry, a variety of efficient automatic lathes,  and specialized rapid development. In order to improve the productivity of small quantities of the workpiece, the late 1940s, lathes with hydraulic copying device be promoted at the same time, multi-tool lathes have also been developed. In the 1950s, the development of the program control lathe with a punch card, latch plate and thumbwheels like. CNC technology in the 1960s for turning, after 70 years of rapid development.

Component

The main components include: headstock, exchange gear box, feed box, apron, turret, tailstock, light bars, screw, bed, foot of the bed and cooling means.

Headstock: its main task is to rotate the main motor sport came after a series of the transmission mechanism of the spindle to give the pros and cons of two different speeds required for steering, while the separation of part of the power headstock the motion to feed me. Headstock spindle lathes are key parts. Processing quality spindle bearing directly affect the smooth functioning of the workpiece, once the rotation accuracy of the spindle is reduced, the machine will reduce the use value.

Feed me: it is also known as pass me, feed tank containing the feed movement of the transmission mechanism, adjust its transmission mechanism, will achieve the desired feed rate or pitch, through light bars or screw motion is transmitted to the knife frame for cutting.

Screw and light bars: to connect the feed box and apron, and the feed box of sports and power to the apron, make apron obtain longitudinal linear motion. Is devoted to turning the screw threads and a variety of settings, other surface during turning of the workpiece, only light bar without screw. Students who want to combine the contents of the apron distinguish between light bars and screw.

Apron: a lathe feed motion control box, built with the rotary motion of the light bar and screw into linear motion mechanism turret, turret achieve transmission via light bars longitudinal feed motion, infeed movement and fast-moving, driven toolholder for longitudinal linear motion by the screw for threading.

Turret: There are two skateboard (medium, small slide), a common component saddle and tool holder body. And promote the tools used to install tools for vertical, horizontal or diagonal movement. Tailstock: mounted on the rail bed, and longitudinal movement along the rail to adjust its working position. After tailstock mainly used to install the top, in order to support long workpieces can also be mounted drills, reamers, etc. hole machining.

Bed: It is turning a large infrastructure component with high precision rail. For supporting and connecting the various components of a lathe, and ensure that all members at work have an accurate relative position.

Cooling system: cooling device mainly by the cooling water pump in the tank pressurized jet cutting fluid to the cutting area, reduce the cutting temperature, away chips, lubricate the machined surface to improve the surface quality tool life and workpiece.