bridge

A bridge is a structure built to span a physical obstacle, such as a body of water, valley, or road, without closing the way underneath. It is constructed for the purpose of providing passage over the obstacle, usually something that is otherwise difficult or impossible to cross. There are many different designs that each serve a particular purpose and apply to different situations. Designs of bridges vary depending on the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, the material used to make it and the funds available to build it. Types of bridges:

•  Beam bridges are horizontal beams supported at each end by substructure units and can be either simply supported when the beams only connect across a single span, or continuous when the beams are connected across two or more spans.
•  A truss bridge is a bridge whose load-bearing superstructure is composed of a truss. 桁héng架桥是一种承载上部结构由桁架组成的桥梁。
•  Cantilever bridges are built using cantilevers - horizontal beams supported on only one end. 悬臂桥是使用仅一端支撑的悬臂水平梁建造的。
•  Arch bridges have abutments at each end. 拱桥两端都有桥台。
•  Tied-arch bridges have an arch-shaped superstructure, but differ from conventional arch bridges.
•  Suspension bridges are suspended from cables.
•  Cable-stayed bridges, like suspension bridges, are held up by cables.

Dr. Mao Yisheng aka. Thomson Eason Mao was a Chinese structural engineer and social activist. He was one of the most famous Chinese structural engineers, a pioneer in bridge construction, and a social activist. 茅以升（1896年1月9日—1989年11月12日），字唐臣，江苏镇江人。土木工程学家、桥梁专家、工程教育家，中国科学院院士，美国工程院院士，中央研究院院士。1955年选聘为中国科学院院士（学部委员）。他主持修建了中国人自己设计并建造的第一座现代化大型桥梁——钱塘江大桥，成为中国铁路桥梁史上的一块里程碑；新中国成立后，他又参与设计了武汉长江大桥。晚年，他编写了《中国桥梁史》、《中国的古桥和新桥》等。

A bridge circuit is a topology of electrical circuitry in which two circuit branches (usually in parallel with each other) are "bridged" by a third branch connected between the first two branches at some intermediate point along them. The best-known bridge circuit, the Wheatstone bridge, was invented by Samuel Hunter Christie and popularized by Charles Wheatstone, and is used for measuring resistance.

An H-bridge is an electronic circuit that switches the polarity of a voltage applied to a load. These circuits are often used in robotics and other applications to allow DC motors to run forwards or backwards.

A network bridge is a computer networking device that creates a single, aggregate network from multiple communication networks or network segments. This function is called network bridging. Bridging is distinct from routing. Routing allows multiple networks to communicate independently and yet remain separate, whereas bridging connects two separate networks as if they were a single network. In the OSI model, bridging is performed in the data link layer (layer 2). If one or more segments of the bridged network are wireless, the device is known as a wireless bridge.

A northbridge or host bridge is one of the two chips in the core logic chipset architecture on a PC motherboard, the other being the southbridge. Unlike the southbridge, the northbridge is connected directly to the CPU via the front-side bus (FSB) and is thus responsible for tasks that require the highest performance. The northbridge, also known as Memory Controller Hub, is usually paired with a southbridge.

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