Flood

Flood (อุทกภัย)

     The word "flood" comes from the Old Englishflod, a word common to Germanic languages (compare GermanFlut, Dutchvloed from the same root as is seen in flow, float; also compare with Latinfluctus, flumen). Deluge myths are mythical stories of a great flood sent by a deity or deities to destroy civilization as an act of divine retribution, and they are featured in the mythology of many cultures.

Primary effects

     The primary effects of flooding include loss of life, damage to buildings and other structures, including bridges, sewerage systems, roadways, and canals.Infrastructure damage also frequently damages power transmission and sometimes power generation , which then has knock-on effects caused by the loss of power.This includes loss of drinking water treatment and water supply, which may result in loss of drinking water or severe water contamination.It may also cause the loss of sewage disposal facilities.Lack of clean water combined with human sewage in the flood waters raises the risk of waterborne diseases , which can include typhoid , giardia , cryptosporidium , cholera and many other diseases depending upon the location of the flood.

Damage to roads and transport infrastructure may make it difficult to mobilise aid to those affected or to provide emergency health treatment.Flood waters typically inundate farm land, making the land unworkable and preventing crops from being planted or harvested, which can lead to shortages of food both for humans and farm animals.Entire harvests for a country can be lost in extreme flood circumstances.Some tree species may not survive prolonged flooding of their root systems 

Secondary and long-term effects

     Economic hardship due to a temporary decline in tourism, rebuilding costs, or food shortages leading to price increases is a common after-effect of severe flooding.The impact on those affected may cause psychological damage to those affected, in particular where deaths, serious injuries and loss of property occur.

Benefits of flood

     Floods (in particular more frequent or smaller floods) can also bring many benefits, such as recharging ground water , making soil more fertile and increasing nutrients in some soils.Flood waters provide much needed water resources in arid and semi-arid regions where precipitation can be very unevenly distributed throughout the year.Freshwater floods particularly play an important role in maintaining ecosystems in river corridors and are a key factor in maintaining floodplain biodiversity.Flooding can spread nutrients to lakes and rivers, which can lead to increased biomass and improved fisheries for a few years.For some fish species, an inundated floodplain may form a highly suitable location for spawning with few predators and enhanced levels of nutrients or food. Fish, such as the weather fish , make use of floods in order to reach new habitats.Bird populations may also profit from the boost in food production caused by flooding. Periodic flooding was essential to the well-being of ancient communities along the Tigris-Euphrates Rivers, the Nile River, the Indus River , the Ganges and the Yellow River among others.The viability of hydropower , a renewable source of energy, is also higher in flood prone regions.

Bibliography : http://en.wikipedia.org/wiki/Flood

Chang and Eng Bunker (แฝดสยามอิน-จัน)

Chan and Eng Bunker (อิน-จัน)

 

     Chan (Chinese: 昌; pinyin: Chāng; Thai: จัน, Jan, RTGS: Chan) and Eng (Chinese: 恩; pinyin: Ēn; Thai: อินIn) Bunker (May 11, 1811 – January 17, 1874) were conjoined twin brothers whose condition and birthplace became the basis for the term "Siamese twins".

Life

     The Bunker brothers were born on May 11, 1811 in Siam (now Thailand ), in the province of Samutsongkram , to a fisherman and his wife (Nok or [Nak]; Thai : นาก ). Because of their Chinese heritage (as they were born from a Thai Chinese father and a Chinese - Malay mother), they were known as the "Chinese Twins" in Siam. They were joined at the sternum by a small piece of cartilage.Their livers were fused but independently complete.Although 19th century medicine did not have the means to do so, modern surgical techniques would have allowed them to be separated.In 1829, British merchant Robert Hunter "discovered" them and paid their family to let them be exhibited as a curiosity during a world tour.In 1839, while visiting Wilkesboro , North Carolina , the twins were attracted to the area and settled on a 110-acre (0.45 km 2 ) farm in nearby Traphill , becoming naturalized United States citizens.Determined to start living a normal life as much as possible, the brothers settled on a plantation , bought slaves ,and adopted the name "Bunker". On April 13, 1843, they married two sisters: Chang to Adelaide Yates and Eng to Sarah Anne Yates.This made their respective children double first cousins .In addition, because Chang and Eng were identical twins, their children were genetically equivalent to half-siblings.Their Traphill home is where they shared a bed built for four.Chang and his wife had 10 children; Eng and his wife had 11.In time, the wives squabbled and eventually two separate households were set up just west of Mount Airy, North Carolina in the community of White Plains – the twins would alternate spending three days at each home.During the American Civil War Chang's son Christopher and Eng's son Stephen both fought for the Confederacy.Chan and Eng lost part of their property as a result of the war, and were very bitter in their denunciation of the government in consequence.After the war, they again resorted to public exhibitions, but were not very successful.They always maintained a high character for integrity and fair dealing, and were much esteemed by their neighbors.The twins died on the same day in January 1874.They always maintained a high character for integrity and fair dealing, and were much esteemed by their neighbors.The twins died on the same day in January 1874.According to the Travel Channel's "Mysteries at the Museum", Chang suffered a stroke the night that he died.Eng awoke to find his brother dead, and called for his wife and children to attend to him.A doctor was summoned to perform an emergency separation, but he was too late.Eng's widow died on April 29, 1892 and Chang's widow died on May 21, 1917.

In - chan and children of the couple.

Memorial

      The fused liver of the Bunker brothers was preserved and is currently on display at the Mütter Museum in Philadelphia, Pennsylvania. Numerous artifacts of the twins, including some of their personal artifacts and their travel ledger, are displayed in the North Carolina Collection Gallery in Wilson Library at the University of North Carolina at Chapel Hill; this includes the original watercolor portrait of Chan and Eng from 1836.

Grave of Eng and Chang Bunker near Mt. Airy, North Carolina

Bibliography : http://en.wikipedia.org/wiki/Chang_and_Eng_Bunker

Earthquake

Earthquake

    An earthquake (also known as a quake , tremor or temblor ) is the result of a sudden release of energy in the Earth's crust that creates seismic waves.
    Earthquakes are measured using observations from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe. The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as the Richter scale.These two scales are numerically similar over their range of validity.Magnitude 3 or lower earthquakes are mostly almost imperceptible or weak and magnitude 7 and over potentially cause serious damage over larger areas, depending on their depth.The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude.The most recent large earthquake of magnitude 9.0 or larger was a 9.0 magnitude earthquake in Japan in 2011 (as of October 2012), and it was the largest Japanese earthquake since records began.Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal. At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity.

Naturally occurring earthquakes
     Tectonic earthquakes occur anywhere in the earth where there is sufficient stored elastic strain energy to drive fracture propagation along a fault plane. The sides of a fault move past each other smoothly and aseismically only if there are no irregularities or asperities along the fault surface that increase the frictional resistance. Most fault surfaces do have such asperities and this leads to a form of stick-slip behaviour. Once the fault has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy. This energy is released as a combination of radiated elastic strain seismic waves , frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake.This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the elastic-rebound theory .It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy.Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction.Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's deep interior.
Induced seismicity
While most earthquakes are caused by movement of the Earth's tectonic plates , human activity can also produce earthquakes.Four main activities contribute to this phenomenon: storing large amounts of water behind a dam (and possibly building an extremely heavy building ), drilling and injecting liquid into wells , and by coal mining and oil drilling. Perhaps the best known example is the 2008 Sichuan earthquake in China's Sichuan Province in May; this tremor resulted in 69,227 fatalities and is the 19th deadliest earthquake of all time.The Zipingpu Dam is believed to have fluctuated the pressure of the fault 1,650 feet (503 m) away; this pressure probably increased the power of the earthquake and accelerated the rate of movement for the fault.The greatest earthquake in Australia's history is also claimed to be induced by humanity, through coal mining. The city of Newcastle was built over a large sector of coal mining areas.The earthquake has been reported to be spawned from a fault that reactivated due to the millions of tonnes of rock removed in the mining process.
Effects of earthquakes
Shaking and ground rupture
Shaking and ground rupture are the main effects created by earthquakes, principally resulting in more or less severe damage to buildings and other rigid structures.The severity of the local effects depends on the complex combination of the earthquake magnitude , the distance from the epicenter , and the local geological and geomorphological conditions, which may amplify or reduce wave propagation.The ground-shaking is measured by ground acceleration.Ground rupture is a visible breaking and displacement of the Earth's surface along the trace of the fault, which may be of the order of several metres in the case of major earthquakes.Ground rupture is a major risk for large engineering structures such as dams , bridges and nuclear power stations and requires careful mapping of existing faults to identify any which are likely to break the ground surface within the life of the structure.

Landslides and avalanches
     Earthquakes, along with severe storms, volcanic activity, coastal wave attack, and wildfires, can produce slope instability leading to landslides, a major geological hazard.Landslide danger may persist while emergency personnel are attempting rescue.
Fires
      Earthquakes can cause fires by damaging electrical power or gas lines.In the event of water mains rupturing and a loss of pressure, it may also become difficult to stop the spread of a fire once it has started.For example, more deaths in the 1906 San Francisco earthquake were caused by fire than by the earthquake itself.

Soil liquefaction

      Soil liquefaction occurs when, because of the shaking, water-saturated granular material (such as sand) temporarily loses its strength and transforms from a solid to a liquid. Soil liquefaction may cause rigid structures, like buildings and bridges, to tilt or sink into the liquefied deposits. For example, in the 1964 Alaska earthquake, soil liquefaction caused many buildings to sink into the ground, eventually collapsing upon themselves.

Tsunami

         Tsunamis are long-wavelength, long-period sea waves produced by the sudden or abrupt movement of large volumes of water.In the open ocean the distance between wave crests can surpass 100 kilometers (62 mi), and the wave periods can vary from five minutes to one hour.Such tsunamis travel 600-800 kilometers per hour (373–497 miles per hour), depending on water depth.Large waves produced by an earthquake or a submarine landslide can overrun nearby coastal areas in a matter of minutes.Tsunamis can also travel thousands of kilometers across open ocean and wreak destruction on far shores hours after the earthquake that generated them.

Human impacts
An earthquake may cause injury and loss of life, road and bridge damage, general property damage (which may or may not be covered by earthquake insurance ), and collapse or destabilization (potentially leading to future collapse) of buildings.The aftermath may bring disease , lack of basic necessities, and higher insurance premiums.

Bibliography : http://en.wikipedia.org/wiki/Earthquake

Data center of facebook

Data center of facebook

     The milestone is a result of Facebook's two-year-old Open Compute Project, in which the company created its own specifications for servers and shared them with the world for anyone to use.Instead of buying servers directly from the likes of HP and Dell, Facebook creates more efficient designs that strip out extraneous hardware and software and then pays original design manufacturers to build them.As we reported in February , the data center in Sweden was set to become Facebook's first containing only Open Compute servers.

     "As our systems come online for the first time, we are proud to say that this is likely to be one of the most efficient and sustainable data centers in the world," Facebook wrote in its announcement, stating that the data center is now handling live traffic from users around the world."All the equipment inside is powered by locally generated hydro-electric energy. Not only is it 100 percent renewable, but the supply is also so reliable that we have been able to reduce the number of backup generators required at the site by more than 70 percent. In addition to harnessing the power of water, we are using the chilly Nordic air to cool the thousands of servers that store your photos, videos, comments, and Likes. Any excess heat that is produced is used to keep our office warm."

       "Nearly all the technology in the facility, from the servers to the power distribution systems, is based on Open Compute Project designs," Facebook continued."This Facebook-founded initiative encourages the development of 'vanity-free' hardware designs that are highly efficient and leave out unnecessary bits of metal and plastic."

       The data center has an impressive PUE rating (power usage effectiveness) of 1.07.This means the building consumes 1.07 watts of power for each watt needed by computing equipment.Facebook has been posting near-real-time PUE data for its US data centers and plans to do the same for the Sweden

       In addition to server designs, the Open Compute Project has created and released designs for server racks, storage systems, motherboards, and interconnects.Last month, Facebook announced that its next goal is to release a design for a top-of-rack switch that can run any type of networking software .This could help give businesses alternatives to Cisco and the other leading network vendors.

Inside the headquarters of Facebook.

A number of Facebook employees came from different countries. To mobilize to help translate the site for over 70 languages​​.

     

References: http://arstechnica.com/information-technology/2013/06/facebook-opens-data-center-filled-entirely-with-servers-it-designed/

Data center of Google

Data center of Google

Efficiency

     Our data centers use 50% less energy than the typical data center.We raise the temperature to 80°F, use outside air for cooling, and build custom servers.

Inside data centers

Environmental, health, and safety

Certifying our high standards:

Google is the first major internet services company to gain external certification of our high environmental and workplace safety standards throughout our US and European data centers. More specifically, all of our US and European data centers have received voluntary ISO 14001 and OHSAS 18001 certifications. Additionally, we’re the first company in the United States to obtain multi-site ISO 50001 Energy Management System certification, covering 6 US data centers.

Our environmental, health, and safety policy:

Google owned and operated data centers will lead the industry in environmental protection, pollution prevention, health, and safety. We will take a proactive approach in our activities and aim to continually improve data center environmental, health, and safety (EHS) performance. We will comply with applicable EHS legal requirements, and as appropriate for other EHS matters, we will implement voluntary standards or best management practices.

Data center locations

     We own and operate data centers around the world to keep our products running 24 hours a day, 7 days a week. Find out more about our data center locations, community involvement, and job opportunities in our locations around the world.

Americas

• Berkeley County, South Carolina
• Council Bluffs, Iowa
• Douglas County, Georgia
• Quilicura, Chile

• Mayes County, Oklahoma
• Lenoir, North Carolina
• The Dalles, Oregon

Asia

• Hong Kong
• Singapore
• Taiwan

Europe

• Hamina, Finland
• St Ghislain, Belgium
• Dublin, Ireland

References : http://www.google.com/about/datacenters/

Computer Network

Computer Network

     A computer network (or data network) is a telecommunications network that allows computers to exchange data.The physical connection between networked computing devices is established using either cable media or wireless media. The best-known computer network is the Internet.

Network devices that originate, route and terminate the data are called network nodes.Nodes can include hosts such as servers and personal computers , as well as networking hardware.Two devices are said to be networked when a process in one device is able to exchange information with a process in another device.

Computer networks support applications such as access to the World Wide Web , shared use of application and storage servers , printers , and fax machines, and use of email and instant messaging applications.The remainder of this article discusses local area network technologies and classifies them according to the following characteristics: the physical media used to transmit signals, the communications protocols used to organize network traffic, along with the network's size, its topology and its organizational intent.

Type of computer network

Local area network

     A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as a home, school, office building, or closely positioned group of buildings.Each computer or device on the network is a node.Wired LANs are most likely based on Ethernet technology.Newer standards such as ITU-T G.hn also provide a way to create a wired LAN using existing wiring, such as coaxial cables, telephone lines, and power lines.

Metropolitan area network

     Metropolitan area network (MAN) is a large computer network that usually spans a city or a large campus.

Wide area network

     A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances.A WAN uses a communications channel that combines many types of media such as telephone lines, cables, and air waves.WAN often makes use of transmission facilities provided by common carriers, such as telephone companies.WAN technologies generally function at the lower three layers of the OSI reference model : the physical layer , the data link layer , and the network layer .

Network topology

  

      Network topology is the layout or organizational hierarchy of interconnected nodes of a computer network.

Common layout are:

•  A bus network : all nodes are connected to a common medium along this medium.This was the layout used in the original Ethernet , called 10BASE5 and 10BASE2 .
• A star network : all nodes are connected to a special central node.This is the typical layout found in a Wireless LAN , where each wireless client connects to the central Wireless access point .
• A ring network : each node is connected to its left and right neighbour node, such that all nodes are connected and that each node can reach each other node by traversing nodes left- or rightwards.The Fiber Distributed Data Interface (FDDI) made use of such a topology.
• Mesh network: each node is connected to an arbitrary number of neighbours in such a way that there is at least one traversal from any node to any other.

Devices

• Modem
• Network interface card
• Wireless access point
• Rcpeater
• Hup
• Bridge
• Switches
• Router
• Gateway

The advantages of computer networks.

• Ease of communication.
• Hardware together.
• Software together.
• Use of data and information sharing.

Home Network

Home Network

       A home network or home area network ( HAN ) is a residential local area network (LAN) for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices.An important function is the sharing of Internet access , often a broadband service provisioned by fiber-to-the-home or via Cable Internet access , Digital Subscriber Line (DSL) or mobile broadband by Internet service providers (ISPs).If an ISP only provides one IP address, a router including network address translation (NAT), proxy server software and typically a network firewall , allows several computers to share the external IP address.The router function may be assumed by a PC with several network interfaces, but a dedicated router device is more common, often including a wireless accesspoint , providing WiFi access.

   Home network

       A home group is a feature that allows shared disk access, shared printer access and shared scanner access among all computers and users (typically all family members) in a home, in a similar fashion as in a small office workgroup, e.g., by means of distributed peer-to-peer networking (without a central server). Additionally, a home server may be added for increased functionality.

        A Windows HomeGroup is a new feature in Microsoft Windows 7 that simplifies file sharing. All users (typically all family members), except guest accounts, may access any shared library on any computer that is connected to the home group. Passwords are not required from the family members during logon. Instead, secure file sharing is possible by means of a temporary password that is used when adding a computer to the HomeGroup.

Physical transmission media

         Wireless radio one of the most common ways of creating a home network is by using wireless radio signal technology; the 802.11 network as certified by the IEEE. Most products that are wireless-capable operate at a frequency of 2.4 GHz under 802.11b and 802.11g or 5 GHz under 802.11a.Some home networking devices operate in both radio-band signals and fall within the standard 802.11n.A wireless network can be used for communication between many electronic devices, to connect to the Internet or to wired networks that use Ethernet technology. Wi-Fi is a marketing and compliance certification for IEEE 802.11 technologies.The WiFi Alliance has tested compliant products certifies them for interoperability.

          Existing home wiring As an alternative to wireless networking, the existing home wiring (coax in North America, telephone wiring in multi dwelling units (MDU) and power-line in Europe and USA) can be used as a network medium. With the installation of a home networking device, the network can be accessed by simply plugging the Computer into a wall socket.

        Power lines The ITU-T G.hn and IEEE Powerline standard, which provide high-speed (up to 1 Gbit/s) local area networking over existing home wiring, are examples of home networking technology designed specifically for IPTV delivery. Recently, the IEEE passed proposal P1901 which grounded a standard within the Market for wireline products produced and sold by companies that are part of theHomePlug Alliance.The IEEE is continuously working to push for P1901 to be completely recognized worldwide as the sole standard for all future products that are produced for Home Networking.

HomePlug, Universal Powerline Association, HomePNA, HomeGrid Forum

Telephone wires: HomePNA, VDSL, VDSL2

Coaxial cables: DOCSIS, Multimedia over Coax Alliance (MoCA), and CWave carry data over coaxial cables, which are frequently installed to support multiple television sets throughout homes.

Network Devices

An example of a simple home network

A home network may consist of the following components:

Infrastructure devices

• A modem for connection to an Internet access service (either a DSL modem using the phone line, or cable modem using the cable internet connection).
• A residential gateway (sometimes called a broadband router) connected between the broadband modem and the rest of the network. This enables multiple devices to connect to the internet simultaneously. Residential gateways, hubs/switches, DSL modems, and wireless access points are often combined.
• A wireless access point, usually implemented as a feature rather than a separate box, for connecting wireless devices

Reference document: http://en.wikipedia.org/wiki/Home_network