Wednesday, February 25, 2009
An RQ-2 Pioneer, a reconnaissance UAV used by the US military during the Gulf and Iraq Wars.
Although most UAVs are fixed-wing aircraft, rotorcraft designs such as this MQ-8B Fire Scout also exist.An unmanned aerial vehicle (UAV) is an unpiloted aircraft. UAVs can be remote controlled or fly autonomously based on pre-programmed flight plans or more complex dynamic automation systems. UAVs are currently used in a number of military roles, including reconnaissance and attack. They are also used in a small but growing number of civil applications such as firefighting when a human observer would be at risk, police observation of civil disturbances and crime scenes, and reconnaissance support in natural disasters. UAVs are often preferred for missions that are too "dull, dirty, or dangerous" for manned aircraft.
There is a wide variety of UAV shapes, sizes, configurations, and characteristics. For the purposes of this article and to distinguish UAVs from missiles, a UAV is defined as capable of controlled, sustained, level flight and powered by a jet or reciprocating engine. Cruise missiles are not classed as UAVs, because, like many other guided missiles, the vehicle itself is a weapon that is not reused, even though it is also unmanned and in some cases remotely guided.
The abbreviation UAV has been expanded in some cases to UAVS (unmanned-aircraft vehicle system). The Federal Aviation Administration has adopted the generic class unmanned aircraft system (UAS) originally introduced by the U.S. Navy to reflect the fact that these are not just aircraft, but systems, including ground stations and other elements.
Main article: History of unmanned aerial vehicles
The earliest UAV was A. M. Low's "Aerial Target" of 1916. A number of remote-controlled airplane advances followed, including the Hewitt-Sperry Automatic Airplane, during and after World War I, including the first scale RPV (Remote Piloted Vehicle), developed by the film star and model airplane enthusiast Reginald Denny in 1935. More were made in the technology rush during the Second World War; these were used both to train antiaircraft gunners and to fly attack missions. Jet engines were applied after WW2, in such types as the Teledyne Ryan Firebee I of 1951, while companies like Beechcraft also got in the game with their Model 1001 for the United States Navy in 1955. Nevertheless, they were little more than remote-controlled airplanes until the Vietnam Era.
Front view of a MQ-1 Predator (Reno Air Show)With the maturing and miniaturization of applicable technologies as seen in the 1980s and 1990s, interest in UAVs grew within the higher echelons of the US military. UAVs were seen to offer the possibility of cheaper, more capable fighting machines that can be used without risk to aircrews. Initial generations were primarily surveillance aircraft, but some were fitted with weaponry (such as the MQ-1 Predator, which utilized AGM-114 Hellfire air-to-ground missiles). An armed UAV is known as an unmanned combat air vehicle (UCAV).
In the future, it is expected more and more roles will be performed by unmanned aircraft. Bombing and ground attack will be added to the surveillance role. Air-to-air combat will likely be the last domain of the human pilot. Search and rescue could be performed by UAVs with heat sensors to help find humans lost in the wilderness, trapped in collapsed buildings, or adrift at sea. When unmanned fighter jets come about, what is so special about unmanned air-to-air vehicles is that there are almost no limits to the G force effects it can take, due to the fact there are no humans piloting the vehicle. In the future UAVs will be able to take full advantage of scramjet technology (scramjets today are unmanned but cannot carry out any useful military tasks yet and are usually only used for testing, see here NASA X-43A, and here NASA's Hyper-X scramjet program), and they will be able to out-maneuver even the most experienced pilots.
Luna X 2000 UAV of the German Army
The Mexican UAV S4 Ehécatl in take-off modeUAVs typically fall into one of six functional categories (although multi-role airframe platforms are becoming more prevalent):
Target and decoy - providing ground and aerial gunnery a target that simulates an enemy aircraft or missile
Reconnaissance - providing battlefield intelligence
Combat - providing attack capability for high-risk missions (see Unmanned combat air vehicle)
Logistics - UAVs specifically designed for cargo and logistics operation
Research and development - used to further develop UAV technologies to be integrated into field deployed UAV aircraft
Civil and Commercial UAVs - UAVs specifically designed for civil and commercial applications
They can also be categorised in terms of range/altitude and the following has been advanced as relevant at such industry events as ParcAberporth Unmanned Systems forum.
Handheld 2,000 ft (600 m) altitude, about 2 km range
Close 5,000 ft (1,500 m) altitude, up to 10 km range
NATO type 10,000 ft (3,000 m) altitude, up to 50 km range
Tactical 18,000 ft (5,500 m) altitude, about 160 km range
MALE (medium altitude, long endurance) up to 30,000 ft (9,000 m) and range over 200 km
HALE (high altitude, long endurance) over 30,000 ft and indefinite range
HYPERSONIC high-speed, supersonic (Mach 1-5) or hypersonic (Mach 5+) 50,000 ft (15,200 m) or suborbital altitude, range over 200km
ORBITAL low earth orbit (Mach 25+)
CIS Lunar Earth-Moon transfer
The U.S. military employs a tier system for categorizing its UAVs.
UAS, or unmanned-aircraft system, is the official U.S. Department of Defense term for an unmanned, aerial vehicle. The term was first officially used in the DoD 2005 Unmanned Aircraft System Roadmap 2005–2030. Many people have mistakenly used the term Unmanned 'Aerial' System, or Unmanned 'Air Vehicle' System.
Officially, the term "unmanned, aerial vehicle" was changed to "unmanned-aircraft system" to reflect the fact that these complex systems include ground stations and other elements besides the actual air vehicles. The term UAS, however, is not widely used, as the term UAV has become part of the modern lexicon.
The military role of UASs is growing at unprecedented rates. In 2005, tactical and theater level unmanned aircraft (UA) alone had flown over 100,000 flight hours in support of Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). Rapid advances in technology are enabling more and more capability to be placed on smaller airframes which is spurring a large increase in the number of Small Unmanned Aircraft Systems (SUAS) being deployed on the battlefield. The use of SUAS in combat is so new that no formal DoD wide reporting procedures have been established to track SUAS flight hours. As the capabilities grow for all types of UAS, nations continue to subsidize their research and development leading to further advances enabling them to perform a multitude of missions. UAS no longer only perform intelligence, surveillance, and reconnaissance (ISR) missions, although this still remains their predominant type. Their roles have expanded to areas including electronic attack (EA), strike missions, suppression and/or destruction of enemy air defense (SEAD/DEAD), network node or communications relay, combat search and rescue (CSAR), and derivations of these themes. These UAS range in cost from a few thousand dollars to tens of millions of dollars, and the aircraft used in these systems range in size from a Micro Air Vehicle (MAV) weighing less than one pound to large aircraft weighing over 40,000 pounds.
UAVs perform a wide variety of functions. The majority of these functions are some form of remote sensing; this is central to the reconnaissance role most UAVs fulfill. Less common UAV functions include interaction and transport.
A Bell Eagle Eye, used by the US Coast GuardUAV remote sensing functions include electromagnetic spectrum sensors, biological sensors, and chemical sensors. A UAV's electromagnetic sensors typically include visual spectrum, infrared, or near infrared cameras as well as radar systems. Other electromagnetic wave detectors such as microwave and ultraviolet spectrum sensors may also be used, but are uncommon. Biological sensors are sensors capable of detecting the airborne presence of various microorganisms and other biological factors. Chemical sensors use laser spectroscopy to analyze the concentrations of each element in the air.
The RQ-7 Shadow is capable of delivering a 20-lb. "Quick-MEDS" canister to front-line troops.UAVs can transport goods using various means based on the configuration of the UAV itself. Most payloads are stored in an internal payload bay somewhere in the airframe. For many helicopter configurations, external payloads can be tethered to the bottom of the airframe. With fixed wing UAVs, payloads can also be attached to the airframe, but aerodynamics of the aircraft with the payload must be assessed. For such situations, payloads are often enclosed in aerodynamic pods for transport.
Unmanned aircraft are uniquely capable of penetrating areas which may be too dangerous for piloted craft. The National Oceanic and Atmospheric Administration (NOAA) began utilizing the Aerosonde unmanned aircraft system in 2006 as a hurricane hunter. AAI Corporation subsidiary Aerosonde Pty Ltd. of Victoria (Australia), designs and manufactures the 35-pound system, which can fly into a hurricane and communicate near-real-time data directly to the National Hurricane Center in Florida. Beyond the standard barometric pressure and temperature data typically cultivated from manned hurricane hunters, the Aerosonde system provides measurements far closer to the water’s surface than previously captured. Further applications for unmanned aircraft can be explored once solutions have been developed for their accommodation within national airspace, an issue currently under discussion by the Federal Aviation Administration.
Rear view of a MQ-1 Predator (Reno Air Show)MQ-1 Predator UAVs armed with Hellfire missiles are now used as platforms for hitting ground targets in sensitive areas. Armed Predators were first used in late 2001 from bases in Pakistan and Uzbekistan, mostly for targeted assassinations inside Afghanistan. Since then, there were several reported cases in such assassinations taking place in Pakistan, this time from Afghan based Predators. The advantage of using a drone, rather than a manned aircraft in such cases, is to avoid a diplomatic embarrassment should the aircraft be shot down and the pilots captured, since the bombings took place in countries deemed friendly and without the official permission of those countries.
A Predator, based in a neighboring Arab country, was used to kill suspected al-Qa'ida terrorists in Yemen on November 3, 2002. This marked the first use of an armed Predator as an attack aircraft outside of a theater of war such as Afghanistan.
Design and development considerations
UAV design and production is a global activity, with manufacturers all across the world. The United States and Israel were initial pioneers in this technology, and U.S. manufacturers have a market share of over 60% in 2006, with U.S. market share due to increase by 5-10% through 2016. Northrop Grumman and General Atomics are the dominant manufacturers in this industry, on the strength of the Global Hawk and Predator/Mariner systems. Israeli and European manufacturers form a second tier due to lower indigenous investments, and the governments of those nations have initiatives to acquire U.S. systems due to higher levels of capability. European market share represented just 4% of global revenue in 2006.
Degree of autonomy
UAV monitoring and control at CBP
HiMAT Remote Cockpit Synthetic Vision Display (Photo: NASA 1984)Some early UAVs are called drones because they are no more sophisticated than a simple radio-controlled aircraft controlled by a human pilot (sometimes called the operator) at all times. More sophisticated versions may have built-in control and/or guidance systems to perform low-level human pilot duties such as speed and flight-path stabilization, and simple prescripted navigation functions such as waypoint following.
From this perspective, most early UAVs are not autonomous at all. In fact, the field of air-vehicle autonomy is a recently emerging field, whose economics is largely driven by the military to develop battle-ready technology. Compared to the manufacturing of UAV flight hardware, the market for autonomy technology is fairly immature and undeveloped. Because of this, autonomy has been and may continue to be the bottleneck for future UAV developments, and the overall value and rate of expansion of the future UAV market could be largely driven by advances to be made in the field of autonomy.
Autonomy technology that is important to UAV development falls under the following categories:
Sensor fusion: Combining information from different sensors for use on board the vehicle
Communications: Handling communication and coordination between multiple agents in the presence of incomplete and imperfect information
Path planning: Determining an optimal path for vehicle to go while meeting certain objectives and mission constraints, such as obstacles or fuel requirements
Trajectory Generation (sometimes called Motion planning): Determining an optimal control maneuver to take to follow a given path or to go from one location to another
Trajectory Regulation: The specific control strategies required to constrain a vehicle within some tolerance to a trajectory
Task Allocation and Scheduling: Determining the optimal distribution of tasks amongst a group of agents, with time and equipment constraints
Cooperative Tactics: Formulating an optimal sequence and spatial distribution of activities between agents in order to maximize chance of success in any given mission scenario
Autonomy is commonly defined as the ability to make decisions without human intervention. To that end, the goal of autonomy is to teach machines to be "smart" and act more like humans. The keen observer may associate this with the development in the field of artificial intelligence made popular in the 1980s and 1990s such as expert systems, neural networks, machine learning, natural language processing, and vision. However, the mode of technological development in the field of autonomy has mostly followed a bottom-up approach, such as hierarchical control systems, and recent advances have been largely driven by the practitioners in the field of control science, not computer science. Similarly, autonomy has been and probably will continue to be considered an extension of the controls field.
To some extent, the ultimate goal in the development of autonomy technology is to replace the human pilot. It remains to be seen whether future developments of autonomy technology, the perception of the technology, and most importantly, the political climate surrounding the use of such technology, will limit the development and utility of autonomy for UAV applications. Also as a result of this, synthetic vision for piloting has not caught on in the UAV arena as it did with manned aircraft. NASA utilized synthetic vision for test pilots on the HiMAT program in the early 1980s (see photo), but the advent of more autonomous UAV autopilots, greatly reduced the need for this technology.
Interoperable UAV technologies became essential as systems proved their mettle in military operations, taking on tasks too challenging or dangerous for warfighters. NATO addressed the need for commonality through STANAG (Standardization Agreement) 4586. According to a NATO press release, the agreement began the ratification process in 1992. Its goal was to allow allied nations to easily share information obtained from unmanned aircraft through common ground control station technology. STANAG 4586-compliant aircraft are equipped to translate information into standardized message formats; likewise, information received from other compliant aircraft can be transferred into vehicle-specific messaging formats for seamless interoperability. Amendments have since been made to the original agreement, based on expert feedback from the field and an industry panel known as the Custodian Support Team. Edition Two of STANAG 4586 is currently under review. There are many systems available today that comply with STANAG 4586, including products by industry leaders such as AAI Corporation, CDL Systems, and Raytheon, all three of which are members of the Custodian Support Team for this protocol.
RQ-4 Global Hawk, a high-altitude reconnaissance UAV capable of 36 hours continuous flight timeBecause UAVs are not burdened with the physiological limitations of human pilots, they can be designed for maximized on-station times. The maximum flight duration of unmanned, aerial vehicles varies widely. Internal-combustion-engine aircraft endurance depends strongly on the percentage of fuel burned as a fraction of total weight (the Breguet endurance equation), and so is largely independent of aircraft size. Solar-electric UAVs hold potential for unlimited flight, a concept championed by the Helios Prototype, which unfortunately was destroyed in a 2003 crash. One of the major problems with UAVs is no capability for inflight refuelling. Currently the US Air Force is promoting research that should end in an inflight UAV refueling capability, which should be available by 2010.
The Defense Advanced Research Projects Agency (DARPA) is to sign a contract on building an UAV which should have an enormous endurance capability of about 5 years. The project is entitled "Vulture". The developers are certain neither on the design of the UAV nor on what fuel it should run to be able to stay in air without any maintenance for such a long period of time.
Wednesday, February 18, 2009
IBNU SINA yang lebih dikenali di Barat dengan nama Avicenna mempunyai nama lengkap Abu Ali al- Huseyn bin Abdullah bin Hassan Ali bin Sina. Beliau merupakan seorang yang berbangsa Parsi. Menurut Ibnu Abi Ushaybi’ah ia lahir pada tahun 375 H, di desa Afshanah dekat kota Kharmaitan Propinzi Bukhara Afghanistan.
Pelajaran pertama yang diterimanya pada zaman kanak-kanak adalah Al-Quran dan sastera yang didapati olehnya secara tidak formal. Ia mula belajar pada usia 5 tahun. Sementara itu sewaktu berumur 10 tahun , beliau telah berjaya menghafal Al-Quran. Pada masa umurnya meningkat 18 tahun Ibnu Sina telah menjadi "Doktor Di Raja". Disamping itu, Ibnu Sina jiga telah menguasai seluruh cabang ilmu pengetahuan yang ada pada waktu itu. Ilmu-ilmu agama seperti tafsir, fiqh, perbandingan agama (ushuluddin), tasawuf dan sebagainya sudah dikuasainya ketika baru berusia 10 tahun.
Pada masa kecilnya, ia dibimbing dan dididik oleh Abu Abdullah Natili, seorang sahabat karib ayahnya, dan ayahnya sendiri. Antara bidang ilmu yang berjaya dikuasainya termasuklah dalam bidang falsafah, kedoktoran, geometri, astronomi, muzik, syair, teologi, politik, matematik, fizik, kimia, sastera dan kosmologi.Beliau pernah berguru dengan al-Farabi iaitu juga seorang ilmuan islam yang terbilang.
Teori-Teori Anatomi Dan Fisiologi
Teori-teori anatomi dan fisiologi dalam buku-buku beliau adalah menggambarkan analogi manusia terhadap negara dan mikrokosmos (dunia kecil) terhadap alam semester sebagai makrokosmos (dunia besar).Misalnya digambarkan bahawa syurga kayangan adalah bulat dan bumi adalah persegi dan dengan demikian kepala itu bulat dan kaki itu empat persegi. Terdapat empat musim dan 12 bulan dalam setahun, dengan itu manusia memiliki empat tangkai dan lengan (anggota badan) mempunyai 12 tulang sendi. Hati (heart) adalah ‘pangeran’-nya tubuh manusia, sementera paru-paru adalah ‘menteri’-nya. Leher merupakan ‘jendela’-nya sang badan, manakala kandung empedu sebagai ‘markas pusat’-nya. Limpa dan perut sebagai ‘bumbung’ sedangkan usus merupakan sistem komunikasi dan sistem pembuangan.
Sementara itu "Canon of Medicine" memuatkan pernyataan yang tegas bahawa "darah mengalir secara terus-menerus dalam suatu lingkaran dan tak pernah berhenti" . Namun ini belum dapat dianggap sebagai suatu penemuan tentang srikulasi darah, kerana bangsa cina tidak membezakan antara urat-urat darah halus (Veins) dengan pembuluh nadi (arferies). Analogi tersebut hanyalah analogi yang digambarkan antara gerakan darah dan siklus alam semesta, pergantian musim dan gerakan-gerakan tubuh tanpa peragaan secara empirik pada keadaan yang sebenarnya.
Al-Qanun Fit-Tibb Dan Hasil Penulisan
Buku tulisan beliau iaitu Al Qanun fil Tib telah diterbitkan di Rom pada tahun 1593.Pada abad ke 12 M Gerard Cremona yang berpindah ke Toledo, Sepanyol telah menterjemahkan buku Ibnu Sina ke bahasa Latin. Buku ini menjadi buku rujukan utama di universiti-universiti Eropah hingga 1500 M.Pada abad ke 16 M , buku ini dicetak 21 kali. Kemudian dialihbahasa kepada Bahasa Inggeris dengan judul Precepts Of Medicine. Ianya telah dicetak sebanyak 15 bahasa dalam masa tidak sampai 100 tahun. Malahan sehingga abad ke-19, bukunya masih diulang cetak dan digunakan oleh para pelajar perubatan
Al-Qanun Fit-Tibb juga digunakan sebagai buku teks kedoktoran di berbagai universiti di Perancis. Misalnya di Sekolah Tinggi Kedoktoran Montpellier dan Louvin telah menggunakannya sebagai bahan rujukan pada abad ke 17 M. Sementara itu Prof. Phillip K. Hitpi telah menganggap buku tersebut sebagai "Ensiklopedia Kedoktoran".
Penulis- penulis Barat telah menganggap Ibnu Sina sebagai ‘Bapa Doktor’ kerana Ibnu Sina telah menyatupadukan teori perubatan Yunani Hippocrates dan Galen dan pengalaman dari ahli-ahli perubatan dari India dan Parsi dan pengalaman beliau sendiri.
Beliau juga turut menghasilkan pelbagai buku yang mengandungi sajak-sajak perubatan yang berjudul “Remedies For The Heart”. Huraian mengenai 760 jenis penyakit bersama dengan kaedah mengubatinya diterangkan di dalam buku tersebut.
Buku-buku yang ditulis beliau bukan saja mengenai bidang perubatan malahan merangkumi juga bidang lain seperti metafizik, muzik, astronomi, philogi ( ilmu bahasa), syair, prosa, dan agama. Sehingga kini buku yang dihasilkan beliau adalah sebanyak 250 buah buku. Karya-karya penulisan yang dihasilkan Ibnu Sina begitu hebat, sehingga menjadi rujukan bagi para ilmuwan di berbagai zaman dan pelbagai tempat, termasuk di dunia Barat.
Pencapaian beliau yang cemerlang bukan sahaja di dalam bidang perubatan, malahan juga beliau turut mencapai tahap kecemerlangan yang tinggi di dalam bidang ilmu logik sehingga diberi gelaran guru ketiga. Di dalam bidang penulisan pula, beratus-ratus karya beliau hasilkan termasuk risalah yang mengandungi hasil sastera kreatif.
Sampai kini ilmunya yang ditulis dalam buku "Al Qanun Fi al- Tib" tetap menjadi dasar bagi perkembangan ilmu kedokteran dan pengobatan dunia. Karena itu Ibnu Sina menjadi bagian tak terpisahkan dari perkembangan ilmu kedokteran dunia. Bukunya "Al Qanun" " diterjemahkan" menjadi "The Cannon" oleh pihak Barat, yang kemudian menjadi rujukan banyak ilmuwan abad pertengahan. Buku itu diantaranya berisi eksiklopedia dengan jumlah jutaan item tentang pengobatan dan obat-obatan. Bahkan diperkenalkan penyembuhan secara sistematis dan dijadikan rujukan selama tujuh abad kemudian ( sampai abad ke-17).
Sebahagian daripada karyanya yang dapat dicatat disini adalah daripada :
1.Bidang logika "Isaguji", "The Isagoge", ilmu logika Isagoge.
2.Fi Aqsam al-Ulum al-Aqliyah (On the Divisions of the Rational Sciences) tentang pembahagian ilmu-ilmu rasional.
3.Bidang metafizika , "Ilahiyyat" (Ilmu ketuhanan)
4.Bidang psikologi , "Kitab an-Nayat" (Book of Deliverence) buku tentang kebahagiaan jiwa.
5. Fiad-Din yang telah diterjemahkan ke dalam bahasa Latin menjadi "Liber de Mineralibus" yakni tentang pemilikan (mimeral).
6.Bidang sastera arab "Risalah fi Asab Huduts al-Huruf" ,risalah tentang sebab-sebab terjadinya huruf.
7.Bidang syair dan prosa "Al-Qasidah al- Aniyyah" syair-syair tentang jiwa manusia.
8.Cerita-cerita roman fiktif , "Risalah ath-Thayr" cerita seekor burung.
9.Bidang politik "Risalah as-Siyasah" (Book on Politics) – Buku tentang politik.
Perintis Pengenalan Penyakit Saraf
Al- Qanun Fit-Tibb telah membincangkan serta mengenegahkan mengenai penyakit saraf. Buku tersebut juga telah mengajar mengenai cara-cara pembedahan dimana telah menekankan keperluan pembersihan luka. Malahan di dalam buku-buku tersebut juga dinyatakan keterangan –keterangan dengan lebih jelas di samping hiasan gambar-gambar dan sketsa-sketsa yang sekaligus menunjukkan pengetahuan anatomi Ibnu Sina yang luas.
Ibnu Sina- Sebagai Seorang Doktor.
Setelah ayahnya wafat, ia meninggalkan Bukhara karena gangguan politik dan pergi ke kota Gorgan, yang tekenal dengan kebudayaannya yang tinggi. Dia diundang oleh Raja Khawarizm, pelindung besar kebudayaan dan pendidikan. Di sana beliau membuka klinik perubatan di samping aktif dalam bidang pendidikan dan turut menghasilkan buku-buku ilmiah. Setelah itu, Ibnu Sina melanjutkan perjalanannya. Antara lain ke Kota Ravy dan Kota Hamadan.
Ibnu Sina pernah di beri gelaran sebagai "Medicorum Principal" atau "Raja Diraja Doktor" oleh kaum Latin Skolastik. Antara gelaran lain yang pernah diberikan kepadanya adalah sebagai "Raja Ubat". Malahan dalam dunia Islam, ia dianggap sebagai "Zenith", puncak tertinggi dalam ilmu kedoktoran . Ibnu Sina menjadi "Doktor Di Raja" iaitu doktor kepada Sultan Nuh 11 bin Mansur di Bukhara pada tahun 378 H/ 997 M iaitu ketika beliau berusia 18 tahun. Pada waktu itu penyakit sultan dalam keadaan parah dan tidak ada doktor lain yang berjaya mengubati baginda. Akan tetapi berkat pertolongan Ibnu Sina baginda kembali pulih.
Perkara yang lebih menakjubkan pada Ibnu Sina ialah beliau juga merupakan seorang ahli falsafah yang terkenal. Beliau pernah menulis sebuah buku berjudul al-Najah yang membicarakan persoalan falsafah. Pemikiran falsafah Ibnu Sina banyak dipengaruhi oleh aliran falsafah al-Farabi yang telah menghidupkan pemikiran Aristotle. Oleh sebab itu, pandangan perubatan Ibnu Sina turut dipengaruhi oleh asas dan teori perubatan Yunani khususnya Hippocrates.
Ibnu Sina merupakan seorang ahli geografi yang mampu menerangkan bagaimana sungai-sungai berhubungan dan berasal dari gunung-ganang dan lembah-lembah. Malahan ia mampu mengemukakan suatu hipotesis atau teori pada waktu itu di mana gagal dilakukan oleh ahli Yunani dan Romani sejak dari Heredotus, Aristoteles sehinggalah Protolemaious. Menurut Ibnu Sina " gunung-ganang yang memang letaknya tinggi iaitu lingkungan mahupun lapisannya dari kulit bumi, maka apabila ia diterajang lalu berganti rupa dikarenkan oleh sungai-sungai yang meruntuhkan pinggiran-pinggirannya. Akibat proses seperti ini, maka terjadilah apa yang disebut sebagai lembah-lembah."
Bidang Geologi, Kimia Dan Kosmologi
Sumbangan Ibnu Sina dalam bidang geologi , kimia serta kosmologi memang tidak dapat di sangsikan lagi. Menurut A.M.A shushtery, karangan Ibnu Sina mengenai ilmu pertambangan (mineral) menjadi sumber geologi di Eropah. Dalam bidang kimia , ia juga meninggalkan penemuan-penemuan yang bermanafaat . Menurut Reuben Levy, Ibnu Sina telah menerangkan bahawa benda-benda logam sebenarnya berbeza antara satu dengan yang lain. Setiap logam terdiri dari berbagai jenis. Penerangan tersebut telah memperkembangkan ilmu kimia yang telah dirintis sebelumnya oleh Jabbir Ibnu Hayyan , Bapa Kimia Muslim.
Sumbangan Ibnu Sina
Ibnu Sina telah memperkembangkan ilmu psikologi dalam perubatan dan membuat beberapa perjumpaan dalam ilmu yang dikenali hari ini sebagai ilmu perubatan psikosomatics "psychosomatic medicine". Beliau memperkembangkan ilmu diagnosis melalui denyutan jantung (pulse diagnosis) untuk mengenal pasti dalam masa beberapa detik sahaja ketidak - seimbangan humor yang berkenaan . Diagnosis melalui denyutan jantung ini masih dipratikkan oleh para hakim (doktor-doktor muslim) di Pakistan, Afghanistan dan Parsi yang menggunakan ilmu perubatan Yunani. Seorang doktor tabii dari Amerika (1981) melapurkan bahawa para hakim di Afghanistan, China, India dan Parsi sanggat berkebolehan dalam denyutan jantung di tempat yang dirasai tetapi mutunya yang pelbagai .Ini merangkumi :
a. Kuat atau denyutan yang lemah.
b. Masa antara denyutan.
c. Kandungannya lembap di paras kulit dekat denyutan itu dan lain-lain lagi.
Dari ukuran-ukuran denyutan jantung seseorang hakim mungkin mengetahui dengan tepat penyakit yang dihinggapi di dalam tubuh si pesakit.Ibnu Sina menyedari kepentingan emosi dalam pemulihan. Apabila pesakit mempunyai sakit jiwa disebabkan oleh pemisahan daripada kekasihnya , beliau boleh mendapati nama dan alamat kekasihnya itu melalui cara berikut:
Caranya adalah untuk menyebut banyak nama dan mengulanginya dan semasa itu jarinya diletakkan atas denyutan (pulse) apabila denyutan itu terjadi tidak teratur atau hampir-hampir berhenti , seseorang itu hendaklah mengulang proses tersebut. Dengan cara yang sedemikan , nama jalan , rumah dan keluarga disebutkan. Selepas itu , kata Ibnu Sina "Jika anda tidak dapat mengubat penyakitnya maka temukanlah si pesakit dengan kekasihnya , menurut peraturan syariah maka buatlah".(Terjemahan).
Ibnu Sina adalah doktor perubatan yang pertama mencatatkan bahawa penyakit paru-paru (plumonary tuberculosis) adalah suatu penyakit yang boleh menjangkit (contagious) dan dia menceritakan dengan tepat tanda-tanda penyakit kencing manis dan masalah yang timbul darinya. Beliau sangat berminat dalam bidang mengenai kesan akal (mind) atas jasad dan telah banyak menulis berkenaan gangguan psikologi.
Beliau telah menghasilkan 250 buah karya dan masih kekal hingga ke hari ini dan termasuklah 116 buah karyanya dalam bidang "Ilmu Perubatan.
Banyak karyanya ditulis dalam bahasa Arab dan juga beberapa dalam bahasa Parsi. "Qanun Fitt Tibb" adalah karyanya yang termasyur , paling selalu dicetak di Eropah pada zaman "Renaissance". Karya Qanun itu telah mempunyai pengaruh yang asas dalam ilmu perubatan di Eropah pada zaman Renaissance dan telah menjadi buku rujukan yang utama di universiti-universiti Eropah hingga ke abad 17 M.
Perubatan Yunani berasaskan teori empat unsur yang dinamakan humours iaitu darah, lendir (phlegm), hempedu kuning (yellow bile), dan hempedu hitam (black bile). Menurut teori ini, kesihatan seseorang mempunyai hubungan dengan campuran keempat-empat unsur tersebut. Keempat-empat unsur itu harus berada pada kadar yang seimbang dan apabila keseimbangan ini diganggu maka seseorang akan mendapat penyakit.
Setiap individu dikatakan mempunyai formula keseimbangan yang berlainan. Meskipun teori itu didapati tidak tepat tetapi telah meletakkan satu landasan kukuh kepada dunia perubatan untuk mengenal pasti punca penyakit yang menjangkiti manusia. Ibnu Sina telah menapis teori-teori kosmogoni Yunani ini dan mengislamkannya.
Ibnu Sina percaya bahawa setiap tubuh manusia terdiri daripada empat unsur iaitu tanah, air, api, dan angin. Keempat-empat unsur ini memberikan sifat lembap, sejuk, panas, dan kering serta sentiasa bergantung kepada unsur lain yang terdapat dalam alam ini. Ibnu Sina percaya bahawa wujud ketahanan semula jadi dalam tubuh manusia untuk melawan penyakit. Jadi, selain keseimbangan unsur-unsur yang dinyatakan itu, manusia juga memerlukan ketahanan yang kuat dalam tubuh bagi mengekalkan kesihatan dan proses penyembuhan.
Ibnu Sina meniggal dunia di Hamdan ,dalam usia 58 tahun pada bulan Ramadhan 428 H/1037 M .Ia dimakamkan di sana. Dalam rangka memperingati 1000 tanun hari kelahirannya (Fair Millenium) di Tehran pada tahun 1955 M ia telah dinobatkan sebagai "Father of Doctor" untuk selamanya-selamanya , dan di sana (Tehran) telah dibangunkan sebuah monemun sejarah untuk itu. Makam beliau di Hamdan telah di kelilingi oleh makam-makam doktor islam yang lain. Hal ini menyebabkan ahli-ahli ilmu yang terkemudian merasa megah kalau dimakamkan di tanah perkuburan di mana "zeninth" itu dimakamkan..
Kesimpulan & Rumusan
1.Ibnu Sina membuktikan sains dan teknologi adalah sangat berkait rapat dengan Islam.Maknanya semakin kita mengkaji alam ini atau tubuh badan kita sendiri semakin kita mensyukuri nikmat yang telah Allah kurniakan kepada kita.
2.Ibnu Sina juga membuktikan kepada dunia bahawa orang Islam juga mampu mengusai ilmu sains dan teknologi kerana di dalam al-Quran juga terdapat sejumlah ayat yang menerangkan keunikan alam ini yang terbukti benar selepas kajian di jalankan oleh orang barat .
3.Ibnu Sina menjadi model yang baik kerana berjaya dan cemerlang antara mengimbangi kehidupan dunianya dan akhiratnya.
4.Umat Islam wajiblah mempelajari semua ilmu di muka bumi ini khususnya sains dan teknologi untuk menjadi contoh kepada penganut-penganut yang lain.
5.Umat Islam wajiblah menggunakan penemuan Sains dan teknologi untuk menambahkan keimanan kepada Allah dan menjauhi diri daripada semua sifat mazmumah,syirik dan kufur kepada Allah.
6.Allah telah menjadikan langit dan bumi supaya manusia berfikir akan kewujudannya sebagai Maha Pencipta yang menciptakan semua kehidupan dan makhluk dengan unik dan istimewa sekali.
7.Ibnu sina adalah seorang Mukmin sejati dikurniakan Allah padanya ilmu perubatan yang sangat berharga dan bermanfaat kepda manusia pada masa kini.
Sunday, February 15, 2009
Hydraulic turbine and electrical generator.
Hydroelectric dam in cross section
• hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator
• The energy extracted from the water depends on the volume and on the difference in height between the source and the water's outflow.
• height difference is called the head
• The amount of potential energy in water is proportional to the head
• Pumped storage hydroelectricity produces electricity to supply high
• Low electrical demand, excess generation capacity is used to pump water into the higher reservoir
• higher demand, water is released back into the lower reservoir through a turbine
• A simple formula for approximating electric power production at a hydroelectric plant is: P = hrk, where P is Power in watts, h is height in meters, r is flow rate in cubic meters per second, and k is a conversion factor of 7500 watts (assuming an efficiency factor of about 76.5 percent and acceleration due to gravity of 9.81 m/s2, and fresh water with a density of 1000 kg per cubic meters
• Annual electric energy production depends on the available water supply
• installations the water flow rate can vary by a factor of 10:1 over the course of a year
• Elimination of the cost of fuel
• The cost of operating a hydroelectric plant is nearly immune to increases in the cost of fossil fuels such as oil, natural gas or coal
• Economically power
• Dams do not burn fossil fuels, they do not directly produce carbon dioxide (a greenhouse gas)
• Reservoirs created by hydroelectric schemes often provide facilities for water sports, and become tourist attractions in themselves
• Environmental damage
• Can be disruptive to surrounding aquatic ecosystems (dams along the Atlantic and Pacific coasts of North America have reduced salmon populations by preventing access to spawning grounds upstream, even though most dams in salmon habitat have fish ladders installed)
• Generation of hydroelectric power changes the downstream river environment
• Large-scale hydroelectric dams have created environmental problems both upstream and downstream.
• Need to relocate the people living where the reservoirs are planned (Three Gorges Dam project in China, the Clyde Dam in New Zealand and the Ilısu Dam in Southeastern Turkey.)
• Failures of large dams, while rare, are potentially serious (the Banqiao Dam failure in Southern China resulted in the deaths of 171,000 people and left millions homeless)
• The creation of a dam in a geologically inappropriate location may cause disasters (the Vajont Dam in Italy, where almost 2000 people died, in 1963)
The Solar Two 10 MW solar power facility, showing the power tower (left) surrounded by the sun-tracking mirrors.
Available solar energy (left) greatly exceeds both potential wind power (center) and global energy consumption (right).
About half the incoming energy from the sun is absorbed by water and land masses, while the rest is reradiated back into space (values are in PW =1015 W).
A solar cell
• Earth receives 174 petawatts of incoming solar radiation (insulations) at the upper atmosphere at any given time
• When it meets the atmosphere, 6 percent of the insolation is reflected and 16 percent is absorbed
• Average atmospheric conditions (clouds, dust, pollutants) further reduce insulation traveling through the atmosphere by 20 percent due to reflection and 3 percent via absorption
• The absorption of solar energy by atmospheric convection (sensible heat transport) and evaporation and condensation of water vapor (latent heat transport) affects the winds and the water cycle
• The total solar energy available to the earth is approximately 3850 zettajoules (ZJ) per year.
• Oceans absorb approximately 285 ZJ of solar energy per year.
• Biomass captures approximately 1.8 ZJ of solar energy per year.
• A solar cell or photovoltaic cell is a device that converts light into electricity using the photoelectric effect
• A solar cell or photovoltaic cell is a device that converts light into electricity using the photoelectric effect
• Total peak power of installed PV is around 6,000 MW as of the end of 2006. It is projected to reach more than 9,000 MW by the end of 2007
• The deployment of PV power depends largely upon local conditions and requirements, most countries are taking an interest in developing PV as one of their options for renewable energy supply.
• Concentrating Solar Thermal (CST) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. It is then used to generate electricity
• Concentrating Solar Thermal technologies require direct insulations to function and are of limited use in locations with significant cloud cover
• A solar trough consists of a linear parabolic reflector that concentrates light onto a receiver positioned along the reflector's focal line
• A parabolic dish or dish/engine system consists of a stand-alone parabolic reflector that concentrates light onto a receiver positioned at the reflector's focal point
• A solar power tower consists of an array of flat reflectors (heliostats) that concentrate light on a central receiver atop a tower
• Focusing is critical and the reflectors track the sun through the day and the year on two axes
• A working fluid (air, water, molten salt) flows through the receiver where it is heated up to 1500 °C before transferring its heat to a power generation or energy storage system
• Elimination of fuel cost
• Save energy consumption
• No pollution
• Long life time energy supply
• Need wider area to concentrating solar energy
• Certain country where less time received the sunlight will be worse
Simple use of biomass fuel (Combustion of wood for heat).
• Biomass is grown from several plants, including miscanthus, switchgrass, hemp, corn, poplar, willow, sugarcane and oil palm (palm oil)
• Although fossil fuels have their origin in ancient biomass, they are not considered biomass by the generally accepted definition because they contain carbon that has been "out" of the carbon cycle for a very long time
Low tech processes include
• composting (to make soil conditioners and fertilizers)
• anaerobic digestion (decaying biomass to produce methane gas and sludge as a fertilizer)
• fermentation and distillation (both produce ethyl alcohol)
More high-tech processes are:
• Pyrolysis (heating organic wastes in the absence of air to produce gas and char. Both are combustible.)
• Hydro gasification (produces methane and ethane)
• Hydrogenation (converts biomass to oil using carbon monoxide and steam under high pressures and temperatures)
• Destructive distillation (produces methyl alcohol from high cellulose organic wastes).
• Acid hydrolysis (treatment of wood wastes to produce sugars, which can be distilled)
• Can save environment from pollutions when used the waste material to make the fuel
• Low cost provided
• can contribute to global warming
DRY STEAM POWER PLANT
• Uses dry steam, typically above 235°C (455°F), to directly power its turbines
• Dry steam is steam that contains no water droplets
• Dry steam plants are used where there is plenty of steam available that is not mixed with water
• Dry steam plants are the simplest and most economical of geothermal plants
FLASH STEAM POWER PLANT
• Use hot water above 182 °C (360 °F) from geothermal reservoirs
• The high pressure underground keeps the water in the liquid state, although it is well above the boiling point of water at normal sea level atmospheric pressure.
• The water is pumped from the reservoir to the power plant, the drop in pressure causes the water to convert, or "flash", into steam to power the turbine
• Flash steam plants, like dry steam plants, emit small amounts of gases and steam.
BINARY CYCLE POWER PLANT
• Used in binary-cycle power plants is cooler than that of flash steam plants, from 107 to 182 °C (225-360 °F)
• The hot fluid from geothermal reservoirs is passed through a heat exchanger which transfers heat to a separate pipe containing fluids with a much lower boiling point
• These fluids, usually Iso-butane or Iso-pentane, are vaporized to power the turbine
• These plants also do not emit any excess gas and, because they use fluids with a lower boiling point than water, are able to utilize lower temperature reservoirs, which are much more common
• clean and safe for the surrounding environment
• unaffected by changing weather conditions
• extremely price competitive in some areas and reduces reliance on fossil fuels and their inherent price unpredictability
• a large geothermal plant can power entire cities while smaller power plants can supply more remote sites such as rural villages
• can adversely affect land stability in the surrounding region
An example of a wind turbine. This 3 bladed turbine is the most common design of modern wind turbines because it minimizes forces related
Worldwide installed capacity and prediction 1997-2010
• Wind turbines can be used to generate electricity in areas with strong, steady winds
• With larger turbines (on the order of one megawatt), the blades move more slowly than older, smaller, units, which makes them less visually distracting and safer for airborne animals
• Wind is a form of solar energy
• Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth
• The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity
• Wind turbines convert the kinetic energy in the wind into mechanical power
• The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity
• A clean fuel source
• Doesn't pollute the air like power plants
• Don't produce atmospheric emissions that cause acid rain or greenhouse gasses
• A domestic source of energy
• The lowest price renewable technologies
• The cost of wind power has decreased dramatically in the past 10 years
• The wind is intermittent and it does not always blow when electricity is needed
• The noise produced by the rotor blades, aesthetic (visual) impacts, and sometimes birds have been killed by flying into the rotors
Washington Public Power Supply System Nuclear Power Plants 3 and 5 were never completed.
• Nuclear power is a type of nuclear technology involving the controlled use of nuclear fission to release energy for work including propulsion, heat, and the generation of electricity
• Produced by a controlled nuclear chain reaction and creates heat—which is used to boil water, produce steam, and drive a steam turbine. The turbine can be used for mechanical work and also to generate electricity
• As of 2004, nuclear power provided 6.5% of the world's energy and 15.7% of the world's electricity, with the U.S., France, and Japan together accounting for 57% of nuclear generated electricity
• A nuclear power plant uses the same fuel, uranium-235 or plutonium-239, a nuclear explosive involves an uncontrolled chain reaction, and the rate of fission in a reactor is not capable of reaching sufficient levels to trigger a nuclear explosion because commercial reactor grade nuclear fuel is not enriched to a high enough level
• The chain reaction is controlled through the use of materials that absorb and moderate neutrons
• Light water reactors use ordinary water to moderate and cool the reactors.
• That negative feedback stabilizes the reaction rate.
• Can generate very high rates of energy
• Long time energy supply
• Long cycle life
• Damage through Uranium mining, radioactive effluent emissions, and waste heat
• Disposal of nuclear waste, with high level waste proposed to go in Deep geological repositories and nuclear decommissioning
• Expensive cost to build it
• Built close to large water sources
• Accidents (The Chernobyl disaster in 1986 at the Chernobyl Nuclear Power Plant in the Ukrainian Soviet Socialist Republic)
Saturday, February 14, 2009
According to engineering area, mechanical engineering is one of the top ten in demand for industry. It is one of the most dynamic and exciting engineering disciplines.The Bureau of Labor Statistics expects an increase of more than 10 percent in the number of mechanical engineering positions through 2014 and the demand for engineers in general is likely to increase during the next 20 years as industrial machinery and processes become increasingly complex. Emerging technologies in biotechnology, materials science, and nanotechnology will also contribute to new job opportunities for mechanical engineers as the skills acquired through earning a degree in mechanical engineering often can be applied in other engineering specialties.Mechanical Engineering is by far the most popular undergraduate degree in engineering. At the graduate level, Mechanical Engineering ranks first in popularity among engineering doctoral students. The field of Mechanical engineering covers the design and analysis of all kinds of systems and technologies with mechanical components, and has applications in energy production, environmental systems, materials, composites, transportation, robotics, manufacturing, machine design, and many more areas. Several key emerging technologies fall fundamentally within the domain of mechanical engineering expertise.
Among these technologies are micro- and nano-scale fabrication processes, energy, and the environment. Modern mechanical engineers can navigate virtual design environments and are adept in computing so they play a significant role in the future development of information technology. Mechanical engineers interested in biotechnology obtain an understanding of life sciences at the undergraduate level and contribute to multi-disciplinary research and industrial projects. Students earn mechanical engineering degrees not only to practice careers in engineering, but also as preliminary training for many other fields such as law, medicine, and business. The demand for mechanical engineers in today's increasingly complex society is growing rapidly, and projections indicate it will stay that way far into the future.The future depends on solving the worldwide problems of energy shortages, environmental pollution, world health, and inadequate food production. Mechanical engineers are heavily involved in finding those solutions. Jobs in mechanical engineering include developing products to improve air and water quality, inventing more efficient energy sources, designing farm equipment to improve crop yield throughout the world, and developing systems for biological research as well as lifesaving medical equipment. In addition to biotechnology, new job openings for mechanical engineers are being created in the emerging areas of micro- and nano- technologies, information technology, and the environment. A mechanical engineer, now more than ever, is someone who can translate scientific theories into real products to improve the quality of life.
Consider design, produce, maintain and improve all kinds of mechanical devices, components, engines and systems. Examples include transportation equipment, environmental control systems, materials handling systems, machine tools, robots, and automated manufacturing equipment. Mechanical Engineers are also involved with
power conversion systems ranging from internal combustion engines to large power-generating stations. They need to know about all forms of energy needed to produce motion or heat - solar, water, wind and nuclear energy as well as conventional fuels. The field is diverse, and Mechanical Engineers can work in different areas including: design,
testing, manufacturing/plant engineering, sales or teaching.
Mechanical Engineers played a very important part in the creation of the mass production factories of the 1920's. Today, manufacturing industries are turning to cost-saving technologies including automated processing and robotics to improve their competitiveness and productivity. Once again Mechanical Engineers are playing a major role.Using CAD (computer-aided design) they are developing new types of automated systems utilizing laser-processing and machining and advanced sensor and imaging technologies. Mechanical Engineers also design and develop service, or mobile robots, and automated guided vehicles,
including space exploration vehicles. Many Mechanical Engineers work in machinery and systems design. Design engineers are mainly concerned with new product development but also upgrade existing designs to achieve desired performance goals.Computers have become an integral part of the design engineer's job. Using CAD systems, engineers create realistic geometric models of objects on a computer terminal screen. They can rotate these images to
view them from any desired angle, and even simulate and analyze the effects of different operating conditions and try out alternative designs. Computer-models are eliminating the need for handmade drawings and experimental physical prototypes.
Testing of products in order to verify or improve their quality is an integral part of both design and manufacturing. Test engineers select or develop the testing apparatus and procedures to be used. If problems arise during testing, or if the product does not perform according to
specifications, test engineers may recommend changes in overall design, in particular components or materials, or in certain manufacturing procedures.Mechanical Engineers who work in manufacturing are responsible for all aspects of production from development or selection of manufacturing methods to overseeing day-to-day operations on the factory floor.
Engineers must be able to design, install and operate complex manufacturing systems made up of people, materials, robotics and other automated equipment. Along with this, they develop and monitor preventive maintenance programs. They may work on teams with design and test engineers, and often develop the product and the production process concurrently. Sales of sophisticated technical products frequently require knowledge
of how the device or system operates. Therefore, Mechanical Engineers are sometimes employed as sales representatives. They solicit new business and furnish technical assistance to customers; they also provide feedback to design engineers on customer problems and needs.
Mechanical Engineers are employed in virtually every industry, with most working for manufacturing firms and a substantial number employed by consulting services. Although some engineers spend most of their time in an office, many jobs require working part of the time in a plant, testing laboratory, machine shop, or installation site. Engineers also travel to professional conferences and training sessions to keep abreast of recent advances in the field.
.Engineering is normally not a physically strenuous job. However, the pressure of deadlines or the need for emergency repairs can cause considerable stress.The employment outlook for Mechanical Engineers nationally is expected to increase about as fast as the average for all other occupations. Some growth will occur as US manufacturers turn to cost-saving
technologies, including robotics and automation to improve their productivity. Other opportunities will occur in high tech fields such as bioengineering, computer mechanics, composite materials, cryogenics and thermosciences. Engineers with skills in CAD, computer-integrated-manufacturing (CIM), robotics and other forefront technologies will be
the most competitive.
Wages vary somewhat between geographical areas and kind of employer. Recent surveys for both the public and private sectors indicate that starting wages are at the $2,500-$3,300 monthly range. Experienced engineers have a monthly range of $4,100- $4,300 and higher. Top wages for a supervising engineer can top $8,000 per month.Fringe benefits usually include paid vacation, sick leave, retirement, health, dental and vision insurance plans. Some employers also offer stock option and/or profit-sharing plans.A bachelor of science in mechanical engineering (BSME) or a related engineering degree is the minimum requirement for most entry-level positions. Some employers prefer a master's degree; others hire only
those who have at least two years' experience.Mechanical Engineers whose work may affect the public welfare (such as consulting engineers and those in decision-making positions in certain governmental agencies) must be registered by the State. To obtain registration, engineers must have at least a BSME degree and two years' engineering experience. They must pass the Engineer-in-Training examination and, later, the professional examination in mechanical engineering. While registration is not required for all jobs, a registered engineer may have a competitive edge for advancement to more responsible positions. Important college preparation courses include algebra, geometry, trigonometry, and physics. Courses in mechanical drawing and drafting, computer science, machine shop and business administration are helpful.
Mechanical Engineers must keep up with new technologies and developments in their field through reading, advanced courses, conferences and professional society seminars. Those who are hired with bachelor's degrees may be expected to work toward their master's. Most companies pay some or all of the costs for career-related education. Experienced engineers may promote to senior or project engineer. Some move into management after several years of technical