تبلیغات
وبلاگ رسمی کتابخانه دیجیتال زبان انگلیسی
پرداخت مبلغ خدمات

مبلغ: تومان
نام :
ایمیل :
موبایل :
آخرین مطالب

» دانلود راهنمای کتاب دستور و نگارش ۲ دکتر فریدون وحدانی ( 1394/11/22 )
» دانلود جزوه راهنمای کلیات زبان شناسی (متن و ترجمه) ( 1394/11/8 )
» دانلود خلاصه روش تدریس زبان انگلیسی لارسن ( 1394/11/8 )
» دانلود پاسخ های تشریحی آزمون های کارشناسی ارشد سال ۷۵-۹۳ آموزش زبان انگلیسی ( 1394/10/22 )
» افتتاح رسمی فروشگاه ( 1394/04/8 )
» آموزش نوین لغات حیاتی زبان انگلیسی یکبار برای همیشه (بر روی عکس کلیک کنید) ( 1394/02/16 )
» مروری بر دیدگاه والتر بنیامین در "نظریه ترجمه" ( 1394/02/8 )
» بزرگترین بسته آموزشی زبان انگلیسی ( 1394/01/17 )
» پیشنهاد فوق العاده ( 1393/12/19 )
» به عموم جوانان در اروپا و امریکای شمالی ( 1393/12/4 )
» To the Youth in Europe and North America ( 1393/12/4 )
» ? What are phrasal verbs ( 1393/12/1 )
» the most common English mistakes made by ESL students ( 1393/11/8 )
» نام و مقطع رشته های دانشگاهی به زبان انگلیسی ( 1393/11/8 )
» بسته های زبان انگلیسی-هر انچه شما میخواهید ( 1393/11/3 )
» فروشگاه تخصصی انجمن ( 1393/10/16 )
» دانلود رایگان ( 1393/09/27 )
» آهنگ Best Song Ever از گروه One Direction ( 1393/09/21 )
» ۲۴ پاورپوینت رشته مترجمی زبان انگلیسی ( 1393/09/20 )
» Dr. Seuss ( 1393/09/16 )
» دانلود کتاب Introducing Translation Studies جرمی ماندی ( 1393/09/16 )
» روز دانشجو مبارک ( 1393/09/16 )
» دانلود رایگان نمونه سوالات پیام نور با پاسخنامه ( 1393/09/14 )
» 57 ways to improve your fluency ( 1393/09/10 )
» Have your head in the clouds ( 1393/09/9 )
» 12 کانال یوتیوب برای یادگیری مکالمه زبان انگلیسی ( 1393/09/8 )
» United Kingdom vs. Great Britain ( 1393/09/8 )
» خودآموز جامع زبان انگلیسی - نکات کاربردی در دنیای واقعی ( 1393/09/7 )
» خودآموز جامع زبان انگلیسی - نکات کاربردی در دنیای واقعی ( 1393/09/7 )
» خودآموز جامع زبان انگلیسی - آموزش گرامر کاربردی ( 1393/09/6 )

آمار بازدید

کل بازدید ها :
بازدید امروز :
بازدید دیروز :
بازدید این ماه :
بازدید ماه قبل :
تعداد نویسندگان :
تعداد کل مطالب :
آخرین بروز رسانی :

کلمات کلیدی


درباره ما


تمامی فعالیت های آموزشی به سایت www.triggerpnu.ir انتقال یافت.
کپی فقط با ثبت صلوات و ذکر منبع مجاز می باشد.
با تشکر

Triggerpnu@gmail.com


Phone: 0938-846-2393

ایجاد کننده وبلاگ : Ali Reza Amiri

فرم تماس با ما
تریگر پی ان یو - تریگر پی ان یو


Is air travel as safe as it should be ?

 

Statistically, air travel is reasonably safe when compared with road, rail and sea. Many countries have a high death and injury rate on the roads; train, ferry and ocean-going ship disasters are regular enough to be commonplace, taking a global view. yet air disasters are usually fatal to all or most concerned and are therefore more widely reported. Consequently there is international pressure to make air travel as safe as possible, and rightly so. Yet no form of travel can be made totally safe. The causes of disaster, whether natural or man-made, can never be completely eliminated.

Looking first at natural causes, at least three can be identified. Bad weather is one. This includes storm, icing and air-pockets in the case of light aircraft; less so in the case of large jets with sophisticated instrumentation. One cause in the case of jets can be large flocks of birds or swarms of insects being sucked into the jet nacelles and thereby stopping the engines. This may happen at low altitudes. Little can be done to prevent this. A third is the alleged danger in what is known as the "Bermuda triangle" in which both ships and aircraft have been lost without trace. In the case of aircraft the reason is though to be loss of horizon due to electrical disturbance.

Most dangers to aircraft however are man-made. The first and obvious danger is collision. In the busiest airports, especially in the tourist season, aircraft may take off as often as every twenty seconds. Much strain is imposed on aircraft dispatchers and traffic control generally. Clearance for dispatch is by radar and computer. Personal fatigue or mechanical failure in a radar center can be very dangerous. Aircraft often have to circle before being given landing permission, and collision or perhaps a near miss can result from mistakes in assigning heights. Most, though not all countries have strict regulations governing air traffic control. Any strike by operatives will cause grounding -- bad enough, but preferable to taking risks.

Another cause of trouble may be the age of the aircraft. Metal fatigue eventually sets in; cracks appear, bits of the aircraft may fall off, even whole engines, or the passenger cabin may lose compression. This means almost certain death to all passengers and crew, and there have been cases where an aircraft has been lost because one of the doors was not properly secured. The important of safety checks before take-off is obvious. So also is the importance of regular and completely efficient servicing. Operatives' licenses can be withdrawn if government inspectors find inefficiency in this area. Most modern aircraft can shut down engines which catch fire, deal automatically with the fire, and proceed on three, or even two engines.

Cabin fires are equally dangerous. They may occur for any reason, but in many cases they result from a crash landing causing the fuel to ignite. two things are important here. First, cabin exit must be unimpeded. Some modern aircraft have built-in chutes for swift escape. Much of course depends on cabin staff and their ability to prevent panic. Second, the seat upholstery must be non-flam. Many people have died from the noxious smoke emanating from flammable upholstery.

There is argument today about emergency drills. Normally a steward will explain life-jackets for use should there be a sea landing, and just mention oxygen masks which are lowered to each seat. Should all these by physically tried out by all passengers prior to take-off ? Such drills are boring and time consuming, but the time may come when they are mandatory.

Some disasters are caused by pilot error. Recently a Shackleton in fog crashed into a hillside in Britain, killing twenty-five young men. the plane has a good safety record. Again recently the pilot of a plane with a faulty engine shut down the good engine due to the failure of his instrumentation. the plane crashed, killing most occupants, and virtually destroying a small village. Sometimes instrumentation can be affected by electronic interference due to unauthorized equipment carried in the hold or hand luggage. This hazard can be eliminated.

Not much can be done about terrorism except through airfield security and electronic vetting of all passengers and luggage. Unhappily not all airports are really efficient in this regard. Efficiency would arrest the terrorist and the hijacker on the airport.

Finally, attempts by carriers to economize on pilot coverage and seating space must be prevented by law. The two essentials are fresh and fully-trained pilots, and reasonable space for movement in emergency.

The answer to the question is no. Much could still be done to avert future disasters


Aviation in peace and war

 

The title of this essay suggests a series of contrasts, perhaps between rocket-firing Hunter and the weekend pilot's Chipmunk, or the Bomber photographing enemy installations from 30,000 feet and the Comet or Boeing long-distance jet airliner. yet the two are inextricably merged; the development of one has always depended on that of the other. Out of the hostile uses of the jet-engine, invented by the Englishman Sir Frank Whittle during the last war, has com the peaceful use of the jet transport and passenger plane. Out of the latest pre-1939 monoplanes came the early wartime fighter, the Hurricane.

Man has always longed to fly like the birds and in the 20th Century his dream has come true. It is said that Michaelangelo invented a quite practicable heavier-than-air flying machine which, had he had aluminium to play with instead of iron, would have worked. Ballooning was quite common-place well before 1900, particularly in France; so were 'gliders' of a sort, which sometimes amounted to 'wings' of bamboo and cloth which served to carry a man a few yards off the ground in a high wind. But true aviation, that is powered 'heavier-than-air' flying, only came about with the development of the petrol engine which, by about 1896, had brought about the prototype motorcar. Primitive aircraft had come into being on both sides of the Atlantic by 1900; Orville and Wilbur Wright built a powered plane a Kitty Hawk which flew for 3 1/2 seconds and traveled 105 feet. Later Bleriot, a Frenchman made history by flying 22 miles across the English Channel in a biplane. Between 1900 and 1914 several countries had made serviceable aircraft, mostly biplanes, gradually overcoming design problems, increasing wing-lift and power, reducing weight and thereby increasing fuel capacity, ironing out facets of maneuverability, and adding both height and speed potential. But pre-1941 aircraft were scarcely more than toys; nobody trusted them for travel purposes, range was severely limited, and as freighters they were not worth considering.

It was the outbreak of first World War which gave a tremendous impetus of flying, and the potential of aircraft as weapons were swiftly realized. Money was spent by both sides on design-research and eventually primitive war planes were mass-produced by both sides. At first, the Handley-Pages and the Camels were visualized only as aerial observation-posts on the Western Front, but this swiftly led to overhead engagements, the pilots shooting it out with revolvers. Later, machine-guns, with a limited are of fire, were fitted, but a great advance came with the Synchronized Machine-gun, capable of firing through a propeller. These aircraft certainly had a nuisance value, as had the dirigibles with their bombs, such as the German Zeppelins, and the early bombers used in open country against concentrated forces, as in T.E. Lawrence's desert campaign, but nobody could portend they were crucial. it is an irony, however, that their development laid the foundation for the 'growing-up' of Civil Aviation between the wars.

In most countries their period was a sad story of governmental indifference and brave efforts by individuals to put flying 'on the map'. The whole world applauded Charles Lindbergh who flew the Atlantic in 1926, and Amy Johnson, who flew alone in a series of short 'hops' to Australia. But flying really grew up in the '30s when metal monoplanes of long range and high reliability standards were produced. The early passenger and freight lines were produced. The early passenger and freight lines were established; seaplanes were invented -- even ski-planes for polar exploration. But Hitler had realized the war-potential of the aircraft, and his early panzer-attacks in Europe and Egypt move on with ruthless efficiency, supported by the high-level saturation bomber and the Stuka dive-bomber. Britain and America had to catch up fast. Hurricanes and Spitfires saved Britain from invasion, and the American Boeings and British Whitleys and Wellingtons virtually destroyed the Ruhr towns in preparation for the Second Front. Airpower was crucial in the allied victory in the East as well as the West. Hiroshima and Nagasaki reversed Pearl Harbor and Singapore.

The nuclear bomb had made the aircraft a terrifying weapon in modern times, and humanity prays that it may be outlawed. But out of war came advance, and the jet aircraft, scarcely in use until 1945, had established international passenger and freight airlines; all countries today recognize the importance of flying as a potential money-earner and a means of cementing international relationship by today's incredibly quick and easy exchange of visitors.

 

Science in the detection of crime

 

Much to his housekeeper's disgust, the great fictional detective Sherlock Holmes carried out scientific experiments in his Baker street rooms in the cause of solving crimes. Since his day, science had played an increasingly important part in both the detection and the proof of crime. Technology, the derivative of science, is used by most countries' police forces today and is responsible for bringing many criminals to justice. Dr Crippen escaped by liner to the Unites States, but an early ship to shore radio telephone enabled the police to arrest him when the line docked.

Footprint casts and fingerprints are traditional methods of detection. Fingerprinting was invented in Great Britain by Francis Galton and has been of fundamental importance in detection for decades. Some countries fingerprint their whole populations, though others, Britain included, regard this as an infringement of personal freedom, and restrict fingerprinting to those accused of a criminal offence, or to those who are screened for certain security categories. science has greatly enhanced the efficiency of this system. Fingerprints are now held on computer, and much time and cost is saved by the fact that information can be exchanged instantaneously throughout the country. Co-operation with the National Crime Information center in the US and with Interpol in the continent of Europe greatly enhances this facility.

Records of convicted criminals are now held on microfilm in conjunction with fingerprints, photographs and personal profiles and stores as computer data. These, again, are capable of instant retrieval countrywide and can also be made available overseas. In the UK this data cannot be disclosed to a jury during a criminal trial, but should the verdict be guilty a previous criminal record becomes available in the matter of sentencing.

The polygraph, or lie detector, is not university sanctioned. Its supporters claim that its ability to record nervous tensions is infallible. Others disagree.

Very recently, DNA printing has revolutionized the process of bringing the criminal to justice, and in civil actions establishing paternity. The minutes quantities of blood, skin, hair or nail-parings can positively identify or eliminate the individual concerned. No two individuals have identical sets of genes. This scientific advance is particularly important in the examination of cars and rooms where crimes have been committed.

Interrogation has always been an important part of criminal investigation. in uncivilized counties, drugs, psychological pressure and often physical torture have been, and still are used. these methods are banned in civilized countries. However, even in the latter, the police occasionally enforce signatures to false statements or to statements which are subsequently mutilated. Taped interviews today now go some way to overcome this abuse, though even tapes can be falsified.

A good deal of crime detection and prevention has been privatized in recent years. some countries allow firearms to security guards, others, such as the UK, do not. Various pieces of technology are in common use. Closed-circuit TV cameras allow centralized observation of customers in large stores. Flood-lighting around buildings can be triggered electronically when anybody approaches in the dark. Foot patrols are issued with light intensifiers, a military development, enabling them to see without being seen. 'Electric eye' burglar alarms have been in use both in public buildings and in private homes for many years.

Observation by police 'on the beat' who know their own areas intimately has always been a recognized and valuable means of crime detection and prevention, bolstering the citizen's sense of security. Unfortunately, this is being replaced by police car patrols. And although the latter are in radio communication with officers on foot and with police headquarters, the general public see this development as retrograde.

Despite all the above, crime is on the increase in many countries. Its detection is no doubt becoming more efficient, due to scientific advance. this is related to an entirely different factor; the decline in religious faith and observance, which instills moral standards into children.

تبلیغات

تبلیغات