Transport engineering (or transportation engineering) is the science of safe and efficient movement of people and goods (transport). It is a sub-discipline of civil engineering.The planning aspects of transport engineering relate to urban planning, and involve technical forecasting decisions and political factors. Technical forecasting of passenger travel usually involves an urban transportation planning model, requiring the estimation of trip generation (how many trips for what purpose), trip distribution (destination choice, where is the traveler going), mode choice (what mode is being taken), and route assignment (which streets or routes are being used). More sophisticated forecasting can include other aspects of traveler decisions, including auto ownership, trip chaining (the decision to link individual trips together in a tour) and the choice of residential or business location (known as land use forecasting). Passenger trips are the focus of transport engineering because they often represent the peak of demand on any transportation system.
Chemical engineering is the branch of engineering that deals with the application of physical science (e.g. chemistry and physics), and life sciences (e.g. biology, microbiology and biochemistry) with mathematics, to the process of converting raw materials or chemicals into more useful or valuable forms. In addition to producing useful materials, modern chemical engineering is also concerned with pioneering valuable new materials and techniques - such as nanotechnology, fuel cells and biomedical engineering. A person employed in this field is called a chemical engineer.
Chemical engineering largely involves the design, improvement and maintenance of processes involving chemical or biological transformations for large-scale manufacture. Chemical engineers ensure the processes are operated safely, sustainably and economically. Chemical engineers in this branch are usually employed under the title of process engineer. A related term with a wider definition is chemical technology.
Biological Engineering or bioengineering (including biological systems engineering) is the application of engineering principles to address challenges in the fields of biology and medicine. Biological engineering applies principles to the full spectrum of living systems, including molecular biology, biochemistry, microbiology, pharmacology, protein chemistry, cytology, immunology, neurobiology and neuroscience. As a study, it encompasses biomedical engineering and it is related to biotechnology. It deals with disciplines of product design, sustainability and analysis to improve and focus utilization of biological systems.The word bioengineering was coined by British scientist and broadcaster Heinz Wolff in 1954. The term bioengineering is also used to describe the use of vegetation in civil engineering construction. The term bioengineering may also be applied to environmental modifications such as surface soil protection, slope stabilisation, watercourse and shoreline protection, windbreaks, vegetation barriers including noise barriers and visual screens, and the ecological enhancement of an area.
Biological Engineering employs knowledge and expertise from a number of pure and applied sciences, such as mass and heat transfer, kinetics, biocatalysts, biomechanics, bioinformatics, separation and purification processes, bioreactor design, surface science, fluid mechanics, thermodynamics, and polymer science. It is used in the design of medical devices, diagnostic equipment, biocompatible materials, and other important medical needs that improve the living standards of societies.
Aerospace engineering is the branch of engineering behind the design, construction and science of aircraft and spacecraft. It is broken into two major and overlapping branches: aeronautical engineering and astronautical engineering. The former deals with craft that stay within Earth's atmosphere, and the latter deals with craft that operate outside of Earth's atmosphere. While "aeronautical" was the original term, the broader "aerospace" has superseded it in usage, as flight technology advanced to include craft operating in outer space. Aerospace engineering is often informally called rocket science
Modern flight vehicles undergo severe conditions such as differences in atmospheric pressure and temperature, or heavy structural load applied upon vehicle components. Consequently, they are usually the products of various technologies including aerodynamics, avionics, materials science and propulsion. These technologies are collectively known as aerospace engineering. Because of the complexity of the field, aerospace engineering is conducted by a team of engineers, each specializing in their own branches of science., The development and manufacturing of a flight vehicle demands careful balance and compromise between abilities, design, available technology and costs.
Acoustical engineering is the branch of engineering dealing with sound and vibration. It is closely related to acoustics, the science of sound and vibration. Acoustical engineers are typically concerned with:
how to reduce unwanted sounds how to make useful sounds using sound as an indication of some other physical property The art of reducing unwanted sounds is called noise control. Noise control engineers work with engineers in most industries to ensure that their products and processes are quiet. There is also a great deal of work done with the assessment and design of buildings, workplaces, airports, road systems in fact most noise generating or noise sensitive developments. There are many standards and documents stating what levels of performance must be achieved for each condition. The various standards and regulations used in the UK are condensed into The Little Red Book of Acoustics.The art of producing useful sounds includes the use of ultrasound for medical diagnosis, sonar, and sound reproduction.A separate and related discipline, audio engineering, is the art of recording and reproducing speech and music for human use.
Engineering has been an aspect of life since the beginnings of human existence. Civil engineering might be considered properly commencing between 4000 and 2000 BC in Ancient Egypt and Mesopotamia when humans started to abandon a nomadic existence, thus causing a need for the construction of shelter. During this time, transportation became increasingly important leading to the development of the wheel and sailing. The construction of Pyramids in Egypt (circa 2700-2500 BC) might be considered the first instances of large structure constructions. Other ancient historic civil engineering constructions include the Parthenon by Iktinos in Ancient Greece (447-438 BC), the Appian Way by Roman engineers (c. 312 BC), and the Great Wall of China by General Meng T'ien under orders from Ch'in Emperor Shih Huang Ti (c. 220 BC). The Romans developed civil structures throughout their empire, including especially aqueducts, insulae, harbours, bridges, dams and roads.Until modern times there was no clear distinction between civil engineering and architecture, and the term engineer and architect were mainly geographical variations referring to the same person, often used interchangeably. In the 18th century, the term civil engineering began to be used to distinguish it from military engineering.
Applications of mechanical engineering are found in the records of many ancient and medieval societies throughout the globe. In ancient Greece, the works of Archimedes (287 BC–212 BC) and Heron of Alexandria (c. 10–70 AD) deeply influenced mechanics in the Western tradition. In China, Zhang Heng (78–139 AD) improved a water clock and invented a seismometer, and Ma Jun (200–265 AD) invented a chariot with differential gears. The medieval Chinese horologist and engineer Su Song (1020–1101 AD) incorporated an escapement mechanism into his astronomical clock tower two centuries before any escapement could be found in clocks of medieval Europe, as well as the world's first known endless power-transmitting chain drive.During the years from 7th to 15th century, the era called the Islamic golden age, there have been remarkable contributions from Muslims in the field of mechanical technology, Al Jaziri, who was one of them wrote his famous "Book of Knowledge of Ingenious Mechanical Devices" in 1206 presented many mechanical designs. He is also considered to be the inventor of such mechanical devices which
Electronics is a branch of science and technology that deals with the flow of electrons through nonmetallic conductors, mainly semiconductors such as silicon. It is distinct from electrical science and technology, which deal with the flow of electrons and other charge carriers through metal conductors such as copper. This distinction started around 1906 with the invention by Lee De Forest of the triode. Until 1950 this field was called "radio technology" because its principal application was the design and theory of radio transmitters, receivers and vacuum tubes.The study of semiconductor devices and related technology is considered a branch of physics, whereas the design and construction of electronic circuits to solve practical problems come under electronics engineering. This article focuses on engineering aspects of electronics.
An electronic component is any physical entity in an electronic system whose intention is to affect the electrons or their associated fields in a desired manner consistent with the intended function of the electronic system. Components are generally intended to be connected together, usually by being soldered to a printed circuit board (PCB), to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Components may be packaged singly or in more complex groups as integrated circuits. Some common electronic components are capacitors, resistors, diodes, transistors, etc
Other more complicated models for the nucleus have also been proposed, such as the interacting boson model, in which pairs of neutrons and protons interact as bosons, analogously to Cooper pairs of electrons.Much of current research in nuclear physics relates to the study of nuclei under extreme conditions such as high spin and excitation energy. Nuclei may also have extreme shapes (similar to that of Rugby balls) or extreme neutron-to-proton ratios. Experimenters can create such nuclei using artificially induced fusion or nucleon transfer reactions, employing ion beams from an accelerator. Beams with even higher energies can be used to create nuclei at very high temperatures, and there are signs that these experiments have produced a phase transition from normal nuclear matter to a new state, the quark-gluon plasma, in which the quarks mingle with one another, rather than being segregated in triplets as they are in neutrons and protons.
Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century (1940–1945). These were the size of a large room, consuming as much power as several hundred modern personal computers (PCs). Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.Simple computers are small enough to fit into a wristwatch, and can be powered by a watch battery. Personal computers in their various forms are icons of the Information Age and are what most people think of as "computers". The embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are however the most numerous.
The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore computers ranging from a mobile phone to a supercomputer are all able to perform the same computational tasks, given enough time and storage capacity.
"Car" and "Cars" redirect here. For other uses, see Car . Karl Benz's "Velo" model (1894) - entered into an early automobile race Passenger cars in 2000 World map of passenger cars per 1000 people.An automobile or motor car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally for the transport of people rather than goods. However, the term automobile is far from precise, because there are many types of vehicles that do similar tasks.As of 2002, there were 590 million passenger cars worldwide (roughly one car per eleven people). Around the world, there were about 806 million cars and light trucks on the road in 2007; they burn over 260 billion gallons of gasoline and diesel fuel yearly. The numbers are increasing rapidly, especially in China and India.
Ferdinand Verbiest, a member of a Jesuit mission in China, built the first steam-powered vehicle around 1672 which was of small scale and designed as a toy for the Chinese Emperor that was unable to carry a driver or a passenger, but quite possibly, was the first working steam-powered vehicle ('auto-mobile').[6][7]Although Nicolas-Joseph Cugnot is often credited with building the first self-propelled mechanical vehicle or automobile in about 1769 by adapting an existing horse-drawn vehicle, this claim is disputed by some[citation needed], who doubt Cugnot's three-wheeler ever ran or was stable. What is not in doubt is that Richard Trevithick built and demonstrated his Puffing Devil road locomotive in 1801, believed by many to be the first demonstration of a steam-powered road vehicle although it was unable to maintain sufficient steam pressure for long periods, and would have been of little practical use.In Russia, in the 1780s, Ivan Kulibin developed a human-pedalled, three-wheeled carriage with modern features such flywheel, brake, gear box, and bearings; however, it was not developed further.[8]François Isaac de Rivaz, a Swiss inventor, designed the first internal combustion engine, in 1806, which was fueled by a mixture of hydrogen and oxygen and used it to develop the world's first vehicle, albeit rudimentary, to be powered by such an engine. The design was not very successful, as was the case with others such as Samuel Brown, Samuel Morey, and Etienne Lenoir with his hippomobile, who each produced vehicles (usually adapted carriages or carts) powered by clumsy internal combustion engines.[9]In November 1881 French inventor Gustave Trouvé demonstrated a working three-wheeled automobile that was powered by electricity. This was at the International Exhibition of Electricity in Paris.[10]Although several other German engineers (including Gottlieb Daimler, Wilhelm Maybach, and Siegfried Marcus) were working on the problem at about the same time, Karl Benz generally is acknowledged as the inventor of the modern automobile
A vehicle (Latin: vehiculum) is a means of conveyance, a carriage or transport. Most often they are manufactured (e.g. bicycles, cars, motorcycles, trains, ships, boats, and aircraft), although some other means of transport which are not made by humans also may be called vehicles; examples include icebergs and floating tree trunks.Vehicles may be propelled or pulled by animals, for instance, a chariot, a stagecoach, a mule-drawn barge, or an ox-cart. However, animals on their own, though used as a means of transport, are not called vehicles, but rather beasts of burden or draft animals. This distinction includes humans carrying another human, for example a child or a disabled person. Means of transport without a vehicle or animal would include walking, running, crawling, or swimming.
A rickshaw is a vehicle that may carry a human and be powered by a human, but it is the mechanical form or cart that is powered by the human that is labeled as the vehicle. For some human-powered vehicles the human providing the power is labeled as a driver.Vehicles that do not travel on land often are called craft, such as watercraft, sailcraft, aircraft, hovercraft, and spacecraftLand vehicles are classified broadly by what is used to apply steering and drive forces against the ground: wheeled, tracked, railed, or skied.
Hardware is a general term that refers to the physical artifacts of a technology. It may also mean the physical components of a computer system, in the form of computer hardware.Hardware historically meant the metal parts and fittings that were used to make wooden products stronger, more functional, longer lasting and easier to fabricate or assemble.[citation needed]Modern hardware stores typically sell equipment such as keys, locks, hinges, latches, corners, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts, especially when they are made of metal.[citation needed]In a more colloquial sense, hardware can refer to military equipment, such as tanks, aircraft, ships or munitions. In the case of vehicles, such may instead be referred to as armour.In slang, the term can also refer to trophies and other physical representations of awards.
The term includes:Application software such as word processors which perform productive tasks for users. Firmware which is software programmed resident to electrically programmable memory devices on board mainboards or other types of integrated hardware carriers. Middleware which controls and co-ordinates distributed systems. System software such as operating systems, which interface with hardware to provide the necessary services for application software. Software testing is a domain independent of development and programming. It consists of various methods to test and declare a software product fit before it can be launched for use by either an individual or a group. Many tests on functionality, performance and appearance are conducted by modern testers with various tools such as QTP, Load runner and Black box testing, to edit a checklist of requirements against the developed code. ISTQB is a certification that is in demand for engineers who want to pursue a career in testing.Testware which is an umbrella term or container term for all utilities and application software that serve in combination for testing a software package but not necessarily may optionally contribute to operational purposes. As such, testware is not a standing configuration but merely a working environment for application software or subsets thereof. Software includes things such as websites, programs or video games, that are coded by programming languages like C or C++."Software" is sometimes used in a broader context to mean anything which is not hardware but which is used with hardware, such as film, tapes and records
Today, the term information technology has ballooned to encompass many aspects of computing and technology, and the term has become very recognizable. The information technology umbrella can be quite large, covering many fields. IT professionals perform a variety of duties that range from installing applications to designing complex computer networks and information databases. A few of the duties that IT professionals perform may include data management, networking, engineering computer hardware, database and software design, as well as the management and administration of entire systems.
When computer and communications technologies are combined, the result is information technology, or "infotech". Information technology is a general term that describes any technology that helps to produce, manipulate, store, communicate, and/or disseminate information. Presumably, when speaking of Information Technology (IT) as a whole, it is noted that the use of computers and information are associated.
The term information technology is sometimes said to have been coined by Jim Domsic of Michigan in November 1981.[citation needed] Domsic, who worked as a computer manager for an automotive related industry, is supposed to have created the term to modernize the outdated phrase "data processing". The Oxford English Dictionary, however, in defining information technology as "the branch of technology concerned with the dissemination, processing, and storage of information, esp. by means of computers" provides an illustrative quote from the year 1958 (Leavitt & Whisler in Harvard Business Rev. XXXVI. 41/1 "The new technology does not yet have a single established name. We shall call it information technology.") that predates the so-far unsubstantiated Domsic coinage.
In recent years ABET and the ACM have collaborated to form accreditation and curriculum standards for degrees in Information Technology as a distinct field of study separate from both Computer Science and Information Systems. SIGITE is the ACM working group for defining these standards.
World War II saw the first large-scale use and further refinement of the aircraft carrier, spawning several types. Escort aircraft carriers, such as USS Bogue, were built only during World War II. Although some were purpose-built, most were converted from merchant ships as a stop-gap measure to provide air support for convoys and amphibious invasions. Light aircraft carriers, such as USS Independence, represented a larger, more "militarized" version of the escort carrier concept. Although the light carriers usually carried the same size air groups as escort carriers, they had the advantage of higher speed as they had been converted from cruisers under construction.Wartime emergencies also saw the creation or conversion of unconventional aircraft carriers. CAM ships, like SS Michael E, were cargo-carrying merchant ships which could launch but not retrieve fighter aircraft from a catapult. These vessels were an emergency measure during World War II as were Merchant aircraft carriers (MACs), such as MV Empire MacAlpine, another emergency measure which saw cargo-carrying merchant ships equipped with flight decks. Battlecarriers were created by the Imperial Japanese Navy to partially compensate for the loss of carrier strength at Midway.[citation needed] Two of them were made from Ise-class battleships during late 1943. The aft turrets were removed and replaced with a hangar, deck and catapult. The heavy cruiser Mogami concurrently received a similar conversion. This "half and half" design was an unsuccessful compromise, being neither one thing nor the other. Submarine aircraft carriers, such as the French Surcouf and the Japanese I-400 class submarine, which was capable of carrying 3 Aichi M6A Seiran aircraft, were first built in the 1920s, but were generally unsuccessful at war.
Modern navies that operate such ships treat aircraft carriers as the capital ship of the fleet, a role previously played by the battleship. The change, part of the growth of air power as a significant factor in warfare, took place during World War II. This change was driven by the superior range, flexibility and effectiveness of carrier-launched aircraft. Following the war, carrier operations continued to increase in size and importance. Supercarriers, typically displacing 75,000 tonnes or greater, have become the pinnacle of carrier development. Most are powered by nuclear reactors and form the core of a fleet designed to operate far from home. Amphibious assault ships, such as USS Tarawa and HMS Ocean, serve the purpose of carrying and landing Marines, and operate a large contingent of helicopters for that purpose. Also known as "commando carriers" or "helicopter carriers", many have a secondary capability to operate VSTOL aircraftLacking the firepower of other warships, carriers by themselves are considered vulnerable to attack by other ships, aircraft, submarines, or missiles. Therefore, aircraft carriers are generally accompanied by a number of other ships, to provide protection for the relatively unwieldy carrier, to carry supplies, and to provide additional offensive capabilities. This is often termed a battle group or carrier group, sometimes a carrier battle group.
MOBILE:
"Mobiles" redirects here. For the UK New Wave pop band, see The Mobiles.Several examples of non-flip mobile phones.A mobile phone or mobile (also called cellphone and handphone,[1] as well as cell phone, wireless phone, cellular phone, cell, cellular telephone, mobile telephone or cell telephone) is a long-range, electronic device used for mobile voice or data communication over a network of specialized base stations known as cell sites. In addition to the standard voice function of a mobile phone, telephone, current mobile phones may support many additional services, and accessories, such as SMS for text messaging, email, packet switching for access to the Internet, gaming, Bluetooth, infrared, camera with video recorder and MMS for sending and receiving photos and video, MP3 player, radio and GPS. Most current mobile phones connect to a cellular network consisting of switching points and base stations (cell sites) owned by a mobile network operator (the exception is satellite phones, which are mobile but not cellular).
A mobile phone, as opposed to a radio telephone, offers full duplex-communication, automatised calling to and paging from a public switched telephone network (PSTN), handoff (am. English) or handover (European term) during a phone call when the user moves from one cell (base station coverage area) to another. A mobile phone offers wide area service, and should not be confused with a cordless telephone, which also is a wireless phone, but only offer telephony service within a limited range, e.g. within a home or an office, through a fixed line and a base station owned by the subscriber.The International Telecommunication Union estimated that mobile cellular subscriptions worldwide would reach approximately 4.1 billion by the end of 2008. Mobile phones have gained increased importance in the sector of Information and communication technologies for development in the 2000s and have effectively started to reach the bottom of the economic pyramid.
WHAT IS TECHNOLOGY?
"Advanced technology" redirects here. For the Advanced Technology form factor, see AT (form factor).By the mid 20th century, humans had achieved a mastery of technology sufficient to leave the atmosphere of the Earth for the first time and explore space.Technology is a broad concept that deals with an animal species' ethology or behavior of usage and of knowledge of tools and crafts, and how it affects the animal species' ability to control and adapt to its environment. Technology is a term with origins in the Greek "technologia", "τεχνολογία" — "techne", "τέχνη" ("craft") and "logia", "λογία" ("saying"). [1] However, a strict definition is elusive; "technology" can refer to material objects of use to humanity, such as machines, hardware or utensils, but can also encompass broader themes, including systems, methods of organization, and techniques. The term can either be applied generally or to specific areas: examples include "construction technology", "medical technology", or "state-of-the-art technology".The human species' use of technology began with the conversion of natural resources into simple tools. The prehistorical discovery of the ability to control fire increased the available sources of food and the invention of the wheel helped humans in travelling in and controlling their environment. Recent technological developments, including the printing press, the telephone, and the Internet, have lessened physical barriers to communication and allowed humans to interact freely on a global scale. However, not all technology has been used for peaceful purposes; the development of weapons of ever-increasing destructive power has progressed throughout history, from clubs to nuclear weapons.
Technology has affected society and its surroundings in a number of ways. In many societies, technology has helped develop more advanced economies (including today's global economy) and has allowed the rise of a leisure class. Many technological processes produce unwanted by-products, known as pollution, and deplete natural resources, to the detriment of the Earth and its environment. Various implementations of technology influence the values of a society and new technology often raises new ethical questions. Examples include the rise of the notion of efficiency in terms of human productivity, a term originally applied only to machines, and the challenge of traditional norms.Philosophical debates have arisen over the present and future use of technology in society, with disagreements over whether technology improves the human condition or worsens it. Neo-Luddism, anarcho-primitivism, and similar movements criticise the pervasiveness of technology in the modern world, opining that it harms the environment and alienates people; proponents of ideologies such as transhumanism and techno-progressivism view continued technological progress as beneficial to society and the human condition. Indeed, until recently, it was believed that the development of technology was restricted only to human beings, but recent scientific studies indicate that other primates and certain dolphin communities have developed simple tools and learned to pass their knowledge to other generations.
MEANING:
A disaster is the tragedy of a natural or human-made hazard (a hazard is a situation which poses a level of threat to life, health, property, or environment) that negatively affects society or environment.In contemporary academia, disasters are seen as the consequence of inappropriately managed risk. These risks are the product of hazards and vulnerability. Hazards that strike in areas with low vulnerability are not considered a disaster, as is the case in uninhabited regions.Developing countries suffer the greatest costs when a disaster hits – more than 95 percent of all deaths caused by disasters occur in developing countries, and losses due to natural disasters are 20 times greater (as a percentage of GDP) in developing countries than in industrialized countries.A disaster can be defined as any tragic event that may involve at least one victim of circumstance, such as an accident, fire, or explosion. Disasters can range from huge killings or wars but many people think that the first disaster was the flood with Noah.
DISASTER MANAGEMENT:
With the tropical climate and unstable landforms, coupled with high population density, poverty, illiteracy and lack of adequate infrastructure,[citation needed] India is one of the most vulnerable developing countries to suffer very often from various natural disasters,[citation needed] namely drought, flood, cyclone, earth quake, landslide, forest fire, hail storm, locust, volcanic eruption, etc. Which strike causing a devastating impact on human life, economy and environment. Though it is almost impossible to fully recoup the damage caused by the disasters, it is possible to (i) minimize the potential risks by developing early warning strategies (ii) prepare and implement developmental plans to provide resilience to such disasters (iii) mobilize resources including communication and telemedicinal services, and (iv) to help in rehabilitation and post-disaster reconstruction. Space technology plays a crucial role in efficient mitigation of disasters. While communication satellites help in disaster warning, relief mobilization and tele-medicinal support, earth observation satellites provide required database for pre-disaster preparedness programmes, disaster response, monitoring activities and post-disaster damage assessment, and reconstruction, and rehabilitation. The article describes the role of space technology in evolving a suitable strategy for disaster preparedness and operational framework for their monitoring, assessment and mitigation, identifies gap areas and recommends appropriate strategies for disaster mitigation vis-à-vis likely developments in space and ground segments.
This article is intended as an accessible, non-technical introduction to the subject. For the main encyclopedia article, see Disaster management.
Various disasters like earthquake, landslides, volcanic eruptions, flood and cyclones are natural hazards that kill thousands of people and destroy billions of dollars of habitat and property each year. The rapid growth of the world's population and its increased concentration often in hazardous environment[citation needed] has escalated both the frequency and severity of natural disasters. With the tropical climate and unstable land forms, coupled with deforestation, unplanned growth proliferation non-engineered constructions which make the disaster-prone areas mere vulnerable, tardy communication, poor or no budgetary allocation for disaster prevention, developing countries suffer more or less chronically by natural disasters.[citation needed] Asia tops the list of casualties due to natural disaster.Among various natural hazards, earthquakes, landslides, floods and cyclones are the major disasters adversely affecting very large areas and population in the Indian sub-continent.[citation needed] These natural disasters are of geophysical origin such as earthquakes, volcanic eruptions, land slides and climatic origin such as drought, flood, cyclone, locust, forest fire. Though it may not be possible to control nature and to stop the development of natural phenomena but the efforts could be made to avoid disasters and alleviate their effects on human lives, infrastructure and property. Rising frequency, amplitude and number of natural disasters and attendant problem coupled with loss of human lives prompted the General Assembly of the United Nations to proclaim 1990s as the International Decade for Natural Disaster Reduction (IDNDR) through a resolution 44/236 of December 22, 1989 to focus on all issues related to natural disaster reduction. In spite of IDNDR, there had been a string of major disaster throughout the decade. Nevertheless, by establishing the rich disaster management related traditions and by spreading public awareness the IDNDR provided required stimulus for disaster reduction. It is almost impossible to prevent the occurrence of natural disasters and their damages.
Flowering plants usually face selective pressure to optimise the transfer of their pollen, and this is typically reflected in the morphology of the flowers and the behaviour of the plants. Pollen may be transferred between plants via a number of 'vectors'. Some plants make use of abiotic vectors - namely wind (anemophily) or, much less commonly, water (hydrophily). Others use biotic vectors including insects (entomophily), birds (ornithophily), bats (chiropterophily) or other animals. Some plants make use of multiple vectors, but many are highly specialised.
Cleistogamous flowers are self pollinated, after which they may or may not open. Many Viola and some Salvia species are known to have these types of flowers.
The flowers of plants that make use of biotic pollen vectors commonly have glands called nectaries that act as an incentive for animals to visit the flower. Some flowers have patterns, called nectar guides, that show pollinators where to look for nectar. Flowers also attract pollinators by scent and color. Still other flowers use mimicry to attract pollinators. Some species of orchids, for example, produce flowers resembling female bees in color, shape, and scent. Flowers are also specialized in shape and have an arrangement of the stamens that ensures that pollen grains are transferred to the bodies of the pollinator when it lands in search of its attractant (such as nectar, pollen, or a mate). In pursuing this attractant from many flowers of the same species, the pollinator transfers pollen to the stigmas—arranged with equally pointed precision—of all of the flowers it visits.Callistemon citrinus flowers.Anemophilous flowers use the wind to move pollen from one flower to the next. Examples include grasses, birch trees, ragweed and maples. They have no need to attract pollinators and therefore tend not to be "showy" flowers. Male and female reproductive organs are generally found in separate flowers, the male flowers having a number of long filaments terminating in exposed stamens, and the female flowers having long, feather-like stigmas. Whereas the pollen of animal-pollinated flowers tends to be large-grained, sticky, and rich in protein (another "reward" for pollinators), anemophilous flower pollen is usually small-grained, very light, and of little nutritional value to animals.
Forests can be found in all regions capable of sustaining tree growth, at altitudes up to the tree line, except where natural fire frequency or other disturbance is too high, or where the environment has been altered by human activity.The latitudes 10° north and south of the Equator are mostly covered in tropical rainforest, and the latitudes between 53°N and 67°N have boreal forest. As a general rule, forests dominated by angiosperms (broadleaf forests) are more species-rich than those dominated by gymnosperms (conifer, montane, or needleleaf forests), although exceptions exist.
Forests sometimes contain many tree species within a small area (as in tropical rain and temperate deciduous forests), or relatively few species over large areas (e.g., taiga and arid montane coniferous forests). Forests are often home to many animal and plant species, and biomass per unit area is high compared to other vegetation communities. Much of this biomass occurs below ground in the root systems and as partially decomposed plant detritus. The woody component of a forest contains lignin, which is relatively slow to decompose compared with other organic materials such as cellulose or carbohydrate.Forests are differentiated from woodlands by the extent of canopy coverage: in a forest, the branches and the foliage of separate trees often meet or interlock, although there can be gaps of varying sizes within an area referred to as forest. A woodland has a more continuously open canopy, with trees spaced further apart, which allows more sunlight to penetrate to the ground between them (also see: savanna).
Among the major forested biomes are:
rain forest (tropical and temperate)
taiga
temperate hardwood forest
tropical dry forest
Forests can be classified in different ways and to different degrees of specificity. One such way is in terms of the "biome" in which they exist, combined with leaf longevity of the dominant species (whether they are evergreen or deciduous). Another distinction is whether the forests composed predominantly of broadleaf trees, coniferous (needle-leaved) trees, or mixed.Boreal forests occupy the subarctic zone and are generally evergreen and coniferous. Temperate zones support both broadleaf deciduous forests (e.g., temperate deciduous forest) and evergreen coniferous forests (e.g., Temperate coniferous forests and Temperate rainforests). Warm temperate zones support broadleaf evergreen forests, including laurel forests.
Tropical and subtropical forests include tropical and subtropical moist forests, tropical and subtropical dry forests, and tropical and subtropical coniferous forests.
Physiognomy classifies forests based on their overall physical structure or developmental stage (e.g. old growth vs. second growth).
Forests can also be classified more specifically based on the climate and the dominant tree species present, resulting in numerous different forest types (e.g., ponderosa pine/Douglas-fir forest).
A number of global forest classification systems have been proposed, but none has gained universal acceptance.[5] UNEP-WCMC's forest category classification system is a simplification of other more complex systems (e.g. UNESCO's forest and woodland 'subformations'). This system divides the world's forests into 26 major types, which reflect climatic zones as well as the principal types of trees. These 26 major types can be reclassified into 6 broader categories: temperate needleleaf; temperate broadleaf and mixed; tropical moist; tropical dry; sparse trees and parkland; and forest plantations. Each category is described as a separate section below.
Water is a ubiquitous chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Other water is trapped in ice caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life on land.
Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea. Over land, evaporation and transpiration contribute to the precipitation over land.
Clean, fresh drinking water is essential to human and other lifeforms. Going without water for a certain period of time can cause kidney failure, eventually leading to death. Depending on the temperature, you can go anywhere from a day to a week before this happens. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita.However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.