No announcement yet.

مكتبة البحووث ^_^

This is a sticky topic.
  • Filter
  • الوقت
  • Show
Clear All
new posts

  • #46
    مكتبه تستاهل التصفيق عليها والله

    جهد واضح وكبيـر

    عساج على القوه هبـله ،،

    اللهم إني اسألك العفو والعافيه


    • #47
      thankx ya qalbeee

      الله يجازي من يسوّي سواتك
      وبذنوب من سوّى سواتك يجازيك

      مشيت درب الثقل وتحب ذاتك
      ماتدري إنه للمهالك يوّديك

      غرّك جمالك ياخسارة حلاتك

      ماتدري ماغير طبعك يحليك


      • #48
        [align=center]Solar Energy

        We have always used the energy of the sun as far back as humans have existed on this planet. As far back as 5,000 years ago, people "worshipped" the sun. Ra, the sun-god, who was considered the first king of Egypt. In Mesopotamia, the sun-god Shamash was a major deity and was equated with justice. In Greece there were two sun deities, Apollo and Helios. The influence of the sun also appears in other religions - Zoroastrianism, Mithraism, Roman religion, Hinduism, Buddhism, the Druids of England, the Aztecs of Mexico, the Incas of Peru, and many Native American tribes.
        We know today, that the sun is simply our nearest star. Without it, life would not exist on our planet. We use the sun's energy every day in many different ways.
        When we hang laundry outside to dry in the sun, we are using the sun's heat to do work -- drying our clothes.
        Plants use the sun's light to make food. Animals eat plants for food. And as we learned in Chapter 5, decaying plants hundreds of millions of years ago produced the coal, oil and natural gas that we use today. So, fossil fuels is actually sunlight stored millions and millions of years ago.
        Indirectly, the sun or other stars are responsible for ALL our energy. Even nuclear energy comes from a star because the uranium atoms used in nuclear energy were created in the fury of a nova - a star exploding.
        Let's look at ways in which we can use the sun's energy.

        Solar Hot Water
        In the 1890s solar water heaters were being used all over the United States. They proved to be a big improvement over wood and coal-burning stoves. Artificial gas made from coal was available too to heat water, but it cost 10 times the price we pay for natural gas today. And electricity was even more expensive if you even had any in your town!
        Many homes used solar water heaters. In 1897, 30 percent of the homes in Pasadena, just east of Los Angeles, were equipped with solar water heaters. As mechanical improvements were made, solar systems were used in Arizona, Florida and many other sunny parts of the United States. The picture shown here is a solar water heater installed on the front roof of a house in Pomona Valley, California, in 1911 (the panels are circled above the four windows).

        By 1920, ten of thousands of solar water heaters had been sold. By then, however, large deposits of oil and natural gas were discovered in the western United States. As these low cost fuels became available, solar water systems began to be replaced with heaters burning fossil fuels.
        Today, solar water heaters are making a comeback. There are more than half a million of them in California alone! They heat water for use inside homes and businesses. They also heat swimming pools like in the picture.
        Panels on the roof of a building, like this one on the right, contain water pipes. When the sun hits the panels and the pipes, the sunlight warms them.
        That warmed water can then be used in a swimming pool.

        Solar Thermal Electricity
        Solar energy can also be used to make electricity.
        Some solar power plants, like the one in the picture to the right in California's Mojave Desert, use a highly curved mirror called a parabolic trough to focus the sunlight on a pipe running down a central point above the curve of the mirror. The mirror focuses the sunlight to strike the pipe, and it gets so hot that it can boil water into steam. That steam can then be used to turn a turbine to make electricity.
        In California's Mojave desert, there are huge rows of solar mirrors arranged in what's called "solar thermal power plants" that use this idea to make electricity for more than 350,000 homes. The problem with solar energy is that it works only when the sun is shining. So, on cloudy days and at night, the power plants can't create energy. Some solar plants, are a "hybrid" technology. During the daytime they use the sun. At night and on cloudy days they burn natural gas to boil the water so they can continue to make electricity.
        Another form of solar power plants to make electricity is called a Central Tower Power Plant, like the one to the right - the Solar Two Project.
        Sunlight is reflected off 1,800 mirrors circling the tall tower. The mirrors are called heliostats and move and turn to face the sun all day long.
        The light is reflected back to the top of the tower in the center of the circle where a fluid is turned very hot by the sun's rays. That fluid can be used to boil water to make steam to turn a turbine and a generator.
        This experimental power plant is called Solar II. It was re-built in California's desert using newer technologies than when it was first built in the early 1980s. Solar II will use the sunlight to change heat into mechanical energy in the turbine.

        The power plant will make enough electricity to power about 10,000 homes. Scientists say larger central tower power plants can make electricity for 100,000 to 200,000 homes

        Solar Cells or Photovoltaic Energy
        We can also change the sunlight directly to electricity using solar cells
        Solar cells are also called photovoltaic cells - or PV cells for short - and can be found on many small appliances, like calculators, and even on spacecraft. They were first developed in the 1950s for use on U.S. space satellites. They are made of silicon, a special type of melted sand.
        When sunlight strikes the solar cell, electrons (red circles) are knocked loose. They move toward the treated front surface (dark blue color). An electron imbalance is created between the front and back. When the two surfaces are joined by a connector, like a wire, a current of electricity occurs between the negative and positive sides.
        These individual solar cells are arranged together in a PV module and the modules are grouped together in an array. Some of the arrays are set on special tracking devices to follow sunlight all day long.
        The electrical energy from solar cells can then be used directly. It can be used in a home for lights and appliances. It can be used in a business. Solar energy can be stored in batteries to light a roadside billboard at night. Or the energy can be stored in a battery for an emergency roadside cellular telephone when no telephone wires are around.
        Some experimental cars also use PV cells. They convert sunlight directly into energy to power electric motors on the car.
        But when most of us think of solar energy, we think of satellites in outer space. Here's a picture of solar panels extending out from a satellite.

        والملف موجوود في المرفقات ع شكل ملف وورد ^_^
        Attached Files
        الله يجازي من يسوّي سواتك
        وبذنوب من سوّى سواتك يجازيك

        مشيت درب الثقل وتحب ذاتك
        ماتدري إنه للمهالك يوّديك

        غرّك جمالك ياخسارة حلاتك

        ماتدري ماغير طبعك يحليك


        • #49


          ¨°o.O (Pearl diving ) O.o°¨

          Introduction :

          For hundreds of years, the finest pearls in the world were found in the waters
          Many thousands of years ago, long before written history, human beings probably discovered the first pearl while searching the seashore for food. Throughout history, the pearl, with its warm inner glow and shimmering iridescence, has been one of the most highly prized and sought-after gems. Countless references to the pearl can be found in the religions and mythology of cultures from the earliest times. The ancient Egyptians prized pearls so much they were buried with them. Cleopatra reportedly dissolved a single pearl in a glass of wine and drank it, simply to win a wager with Mark Antony that she could consume the wealth of an entire nation in just one meal.
          The ancient pearling industry provided the only real income for the people of what is now the UAE. The land was too barren to allow any farming and the people were generally too concerned with finding water, food and other provisions to consider trying to make money. The barter system was their way of trading. A few families would leave the nomadic desert lifestyle and settle on the coast to fish. Some of the fishermen probably found the occasional pearl when wading in the shallows, and kept it until there was an opportunity to barter it. To gather enough oysters to make a living, however, required a huge communal effort, as well as people who were able to dive to depths of around 40 metres without equipment, in order to access the offshore oyster beds.
          As India became increasingly prosperous in the eighteenth and nineteenth centuries, demand for pearls grew. What had been little more than a cottage industry became a major part of local life. Merchants would provide the capital to provide and equip a boat for the diving season, in return for a majority share of the profit accumulated from the sale of the pearls. The rest of the profit was distributed between the captain (nakhutha) and the crew. Pearling offered the possibility of comparative riches if one was lucky enough to be on a boat that discovered a top quality pearl or two. There is evidence of a single pearl being sold for fifteen thousand pounds (sterling) during the 1920s - *****alent to more than three hundred and fifty thousand pounds today1.
          In response to the increased demand for pearls, many more families settled permanently in the coastal villages, which began to grow in importance and influence, particularly Abu Dhabi and Dubai. Others would live on the coast during the four months of the main pearling season, from May to September, and return to the desert in the winter.
          British government papers from the 1920s describe the pearling industry in Bahrain, which would have been almost identical to Dubai's.
          Until they clear the harbour the boats are propelled by heavy oars, each pulled by two men, who sing the song of the pearlers as they row. Often the fleet returns at night when the moon and the tide are full. The sound of the sailors chanting and the splash of the oars is carried across the still water to the town. The sight of hundreds of white sails, some of them coloured orange by the light of the fires burning on the decks, is one of the most picturesque in the world.
          Australian Pearling
          In the 1870s, divers off the coast of Australia discovered something great. It was the Pinctada maxima oyster. The large size of the oysters attracted the attention of local traders. In the beginning, the oysters were pickup up by Aboriginal nacked divers. Most of these divers were women. They had a larger lung capacity then the male divers and could pick up more ****ls in one dive. Soon after that pearling schooners filled with Sri Lankan divers began to harvest the oysters. Still for its ****l rather than for the pearls they contained.
          The early luggers were sail-powered and only catered for one diver's apparatus, but by the 1930s, most vessels were motorised and mechanical air pumps allowed two divers per boat.
          The Pinctada maxima oysters grow in the waters of Australia, Papua New Guinea, Indonesia, the Philippines, Thailand, and Myanmar (Burma). The saltwater pearls they can contain come in both silver- and gold-lipped form. The colors can range from white to gold. Overtones of the silver-lipped oyster has overtones of silvery white or bluish white. The gold-lipped variety has overtones of gold, cream or silver. The size of South Sea pearls range from 10 to 20 millimeters, but pearls larger than 16 millimeters are rare.
          In the beginning, the oysters were so plentiful that at low tide they could be picked from the exposed sand. As the oysters became depleted, more and more sophisticated diving methods had to be used. Before the invention of synthetics like plastic, Mother of Pearl ****l was used across the world to make buttons, in jewelery and for decoration. A pearling settlement was founded at Roebourne Bay in 1880. In 1883 it was ****d Broome, after the then Governor of Western Australia.
          By 1901 the pearling trade employed 2000 people from many nations. The majority were Japanese and Malaysian, but Chinese, Filipino, Amborese, Koepanger (Timorese) and Makassan workers, as well as Aboriginal Australians and people from a range of European nations worked in the pearl trade.
          As the Australian pearl industry boomed, the small town of Broome became the pearling center. In fact, South Sea pearls were originally called "Broome pearls". Within three years of the original discovery, Australia was supplying 75 percent of the world's supply of mother-of-pearl for making shirt buttons.
          In the early years of the twentieth century the pearl ****l trade boomed. By 1912 there were more than 400 pearl luggers working from the port of Broome, spending months at sea gathering the precious ****l and pearls. It is said that before the First World War Broome was the source of three quarters of the world's pearl ****l.
          Like many other parts of Australia, Broome was greatly effected by the First World War. The international trade in the ****l stopped for 2 years. ****l could not be sold and sat in storage in Broome. Pearling crews could not work and the whole town suffered.
          While the 1920s saw a recovery in the industry, the 1930s-1950s were difficult for Broome's pearl trade. The great depression made it hard to get good prices for pearl ****l. The natural pearls found from harvested oysters were a rare bonus for the divers. Many fabulous specimens were found over the years. By the 1930s, over harvesting had severely depleted the oyster beds. The government was forced to strictly regulate the harvest to prevent the oysters from becoming extinct.
          By 1939 only 73 luggers and 565 people were left in the industry and during the Second World War, pearling virtually stopped. Japanese divers discreetly went home or were interned. Broome was bombed, destroying many of the remaining luggers.
          After the war, anyone who had known Broome in its roaring days would hardly have known the place, and a mere 15 boats on average worked the fishery, employing around 200 people.
          The divers were mostly Japanese from the Taiji province. Their diving ritual would often begin by downing a bottle of port, before donning their diving helmets, after which they would be lowered over the lugger's side to spend hours underwater.
          On the bottom they struggled about in their heavy gear, often almost horizontal, frantically scooping oysters into bags because divers were paid by the amount of ****l they collected. Pity the diver on the bottom when his lugger was smashed by one of the four cyclones to catch the pearling fleet at sea between 1908 and 1935. The death toll for these is only approximate but it is known that more than 100 boats and nearly 300 Japanese perished, and are commemorated at the Japanese cemetery in Broome.
          In total, more than 800 divers and their support crews lost their lives because of cyclones between 1882 and 1935. In only 3 years, 1912 to 1915, 93 divers died from the bends. These were boom years for the industry, but the price in human terms was very high.
          Commercial pearl culturing
          The first commercial pearl culturing farm began in Western Australia in 1956. People in Broome began to look at growing pearls, rather than harvesting their ****ls. In 1956, the Kuri Bay cultured Pearl farm produced their first World Superior pearl. Today, Australia produces about 60 percent of the world's South Sea cultured pearls.
          Pearl farming continues to be Broome's major industry. In 1992 there were 12 cultured pearl farms operating around Broome. Little of early days remains - a couple of luggers, a few historic buildings on new sites, rotting jetties, the Japanese cemetery of gracefully calligraphed stones, the modest but absorbing museum and a few helmets, now valuable artefacts and integral parts of pearl shop displays.
          Seeding involves cutting a small section of mantle from a donor oyster and placing it next to bead which is implanted in the oyster, this grafting process forms a sac round the bead and excretes nacre, thus forming a pearl. The seeded oyster is then returned to the sea to recover before being taken to the pearl farm.
          Normal growing time is two years but the cages are removed at regular intervals, the ****ls cleaned and rotated, to assure the best possible results in forming a cultured pearl.
          Most farms now use X-ray machines to check if the bead has been rejected, if so the oyster can be reseeded.
          Good healthy oysters can be seeded up to three times, producing a pearl every two years. Oysters that are still healthy are then used to produce "Mabe" or half pearls. This is done by cementing half beads of varying shapes onto the ****l inside the oyster, up to seven can be placed in one oyster.
          These are harvested by drilling the pearl ****l with the pearl and processing the half pearl. These are made round, oval, drop or heart shape



          الله يجازي من يسوّي سواتك
          وبذنوب من سوّى سواتك يجازيك

          مشيت درب الثقل وتحب ذاتك
          ماتدري إنه للمهالك يوّديك

          غرّك جمالك ياخسارة حلاتك

          ماتدري ماغير طبعك يحليك


          • #50
            روعـــــهـ الموضوع

            فديتج انتي وبحوثج :pماشالله عليج

            يعطيـــج الف عافيه يا قلبي


            • #51

              تسلمين غلاى بس موكله منى اكيدمن النت
              الله يجازي من يسوّي سواتك
              وبذنوب من سوّى سواتك يجازيك

              مشيت درب الثقل وتحب ذاتك
              ماتدري إنه للمهالك يوّديك

              غرّك جمالك ياخسارة حلاتك

              ماتدري ماغير طبعك يحليك


              • #52
                مشكووووووووووووووووره الله لا يحرمنا منج ومن طلتج
                Go under the sixty


                • #53
                  السلام عليكم

                  انا اشكرك جزيل الشكر لأن :
                  اولاً : نفس البحث المطلوب
                  ثانياً : صارلي 3 اسابيع ادوره

                  فجزاك الله خير ويفتحلك 1000000000000000000 باب رزق قول آمين

                  اخوك / جمعان بوند <<< النك نيم مو اسمي للعلم
                  تغيب أو مآتغيب أعرف كأنك حآضر و موجود ...
                  ....................................... مثل ماقلت لك دايم { حقوق الطبع محفوظه }



                  • #54
                    محولا بس انطروا

                    Tslmeen 7ayatee wala ;**

                    جمعان بوند

                    Al7mdalah yalla inshallah alnjaa7 gool ameen
                    الله يجازي من يسوّي سواتك
                    وبذنوب من سوّى سواتك يجازيك

                    مشيت درب الثقل وتحب ذاتك
                    ماتدري إنه للمهالك يوّديك

                    غرّك جمالك ياخسارة حلاتك

                    ماتدري ماغير طبعك يحليك