Manufacturers of both systems say they are aware of possible public concern over computerized drivers. Neither system is entirely autonomous, as there will be on board a human driver to regulate the vehicle's speed and take over steering should the on-board system malfunction. This is in line with the local regulations of most cities. Despite reassurances, not everyone is comfortable with the idea of automatic steering systems, however. "We're not convinced about safety," says Mark Reddie, principal planner for the Phoenix Public Transit Department, which is also considering buying the new trams. "They haven't mass-produced them yet and we don't know how reliable they will be."
Questions 1-5
Classify the following statements as applying to
AP hileas only
BO mni only
CB oth vehicles
Write the appropriate letters A-C in boxes 1-5 on your answer sheet.
1. steers itself
2. follows a painted line
3. still being tested
4. follows magnets
5. uses Dutch technology
Questions 6-9
Complete the labels in the diagram below.
Choose your answers from the box below the diagram, and write them in boxes 6-9 on your answer sheet.
NB There are more words/phrases than spaces, so you will not use them all.
DIAGRAM
Sketch of the Omni electric vehicle system cameras sensors wheelchair section on-board computer upper deck magnets lower deck
Questions 10-13
Complete the summary below. Choose your answers from the box below the summary, and write them in boxes 10-13 on your answer sheet.
NB there are more words/phrases than spaces, so you will not use them all.
The major advantage of the new 10 trams is the absence of 11. In addition, compared to motor-driven public transport vehicles, the trams make the processes of 12 and 13 more rapid.
computer-steered Dutch alighting virtual drivers tracks computers boarding kerbs pollution-free gridlocked
READING PASSAGE 2
You should spend about 20 minutes on Questions 14-27 which are based on Reading Passage 2.
Asian Economies Not as Vulnerable as Before
A Central bank governors from the Asia-Pacific region, at a recent meeting warned that the global trade environment is much tougher for their countries now than during the Asian crisis of four years ago. Singapore is in recession, and South Korea, Malaysia, Thailand, Indonesia, Taiwan and the Philippines have sharply slowing growth. The only bright spot is China, which has maintained brisk output growth because stronger investment and household spending have more than offset the regional export slowdown.
B However, a new financial crisis does not seem to be looming for the region, as some remarkable changes have taken place over the past four years. These changes mean that the region's economies are likely to experience slower but still positive growth this year, and stronger growth next year. The first change is that the economies of Korea, Thailand and Indonesia can no longer be broken by a stampede of foreign bank lenders. The hot money has already gone. According to the most recent International Monetary Fund statistics, net international bank claims in East Asia have fallen by US$354 billion over the last four years. Loans have been repaid by stronger flows of foreign direct investment, by lending from international institutions and by the re-emergence of a bond market in the first half of last year, as well as through large trade surpluses resulting from imports growing more slowly than exports. In the four years from 1997 to 2000, these economies accumulated current account surpluses of US$239 billion, compared to a cumulative deficit of US$88 billion during the five years from 1992.
C Large current account surpluses have seen not only foreign debt reduced, but also big reserves accumulated. These reserves are seen as a cushion against future financial shocks. The reserves in Southeast Asia have increased by US$214 billion in recent years. The central banks of China, Hong Kong and Taiwan hold most of this sum. Moreover, the central banks of the region have agreed on swap arrangements, which could allow the reserves for one currency to be used in the defense of another in case of the threat of another Asian financial crisis. As noted by a report prepared by the regional central banks, intervention is most effective when coordinated.
D These changes defend against a stampede and contagion, but do not, in themselves, encourage growth. That depends on the regional shift toward more flexible exchange rates. Although far from floating freely, most regional exchange rates are no longer hostage to unhedged US dollar bank debt or to entrenched convictions that exchange rate stability is essential. Managed floats have been adopted in most regional economies. Responding to the stronger US dollar, falling exports and slowing imports, these exchange rates have been depreciating. For example, the Singapore dollar recently reached a ten-year low, while the Taiwan dollar reached a 15-year low.
E Foreign direct investment is slowing, and exports are tumbling, but with room to expand domestic demand there are good reasons to think that the region will get through the most serious global downturn in a decade. Foreign investment flows and domestic reconstruction will maintain China's growth. Even South Korea, Singapore and Taiwan—all highly dependent on technology exports to the US—are now buttressed by trade surpluses, huge reserves and flexible exchange rates. All these factors are favorable for expanding domestic demand.
F The perennial problems of the Philippines apart, the economies at the greatest risk are those of Thailand and Malaysia, because they are attempting to sustain pegged exchange rates, and this weakens their ability to respond to sudden strains on their currencies. Although Thailand has sharply reduced its foreign debt, it has pegged its US dollar exchange rate at about 45 baht. Without strong capital controls,the informal peg limits Thailand's freedom to ease interest rates. As for Malaysia, its peg depends on its reserves, which have fallen by US$6 billion during the past year as the country has defended an exchange rate appreciating against those of its neighbors.
Questions 14-18
Reading Passage 2 has six paragraphs A-F. Choose the most suitable headings for paragraphs B-F from the list of headings below. Write the appropriate numbers (i-ix) in boxes 14-18 on your answer sheet.
NB There are more headings than paragraphs, so you will not use them all.
List of Headings
i. Disappearance of hot money
ii. Changes in the region's economies
iii. The role of the US dollar
iv. The region's weak spots
v. The importance of currency reserves
vi. Swap arrangements
vii. The need for flexible exchange rates
viii. Expanding domestic demand
ix. The Philippines' economic problems
14. Paraghraph B
15. Paraghraph C
16. Paraghraph D
17. Paraghraph E
18. Paraghraph F
Questions 19-22
Using NO MORE THAN THREE WORDS from the passage, answer the following questions. Write your answers in boxes 19-22 on your answer sheet.
19. Who is cooperating to stave off another Asian financial crisis?
20. According to the author, what do the changes in the region's economies NOT do?
21. Which country is an exception to the region's slow economic growth?
22. When was the last most serious worldwide economic slowdown?
Questions 23-27
Do the following statements agree with the information in Reading Passage 2? In boxes 23-27 on your answer sheet write
YES if the statement agrees with the information
NO if the statement contradicts the information
NOT GIVEN if there is no information on this in the passage
23. The changes in the region's economies will accelerate their growth.
24. Pegged exchange rates are a danger to Thailand and Malaysia.
25. Most of the regional economies allow their exchange rates to float freely.
26. To survive the global economic slump, the region must export more than it imports.
27. Central bank governors are optimistic about the region's economic future.
READING PASSAGE 3
You should spend about 20 minutes on Questions 28-40 which are based on Reading Passage 3.
The Vikings' Voyage to Eternity
Since the Merovingian Age, during the post-Roman era of the 6th-7th centuries AD, Norsemen have been associated with ships—for trade, exploration, and of course war. No aspect of Viking culture was entirely separate from the influence of ships, including their view of death. In fact, kings and heroes, believing that they would sail to the other world after death, had themselves buried in their ships. This is amply attested to by the epics and sagas which tell of the heroic deeds of the Vikings, many of which have survived to our own day. The greatest details regarding early Scandinavian history, including the custom of ship burial, come from the writings of the Icelandic chronicler Snorri Sturluson,who composed the Heimskringla (History of the Kings of Norway) sometime between AD 1220 and 1235, plus numerous other works. Although much is lost in modern translations, the original poetry of the sagas remains on many levels, and historians are ever grateful to their predecessor for his attention to detail. For about four centuries, the sagas and legends were meticulous in their portrayal of ships. Documentation, of course, may have been embellished for the sake of a good story.
In addition to the legends, there is visible evidence of the pervasive influence of ships and the sea in Viking lore, as a number of ship burials have been discovered in the past two centuries. Therefore, we can use both the archaeological and the literary evidence to piece together a small window into the world of the Vikings. It is particularly interesting that the ships that do remain to this day were buried on land, an intriguing practice which, due to its pagan implications,died out soon after the Viking conversion to Christianity. Boat burials, in combination with sagas, indicate that Viking activity, whether trading or raiding, depended upon reliable ships to sail, and without them the longer sea crossings that we know to have occurred would have been impossible. The voyages that had become commonplace in the 9th century would have been unthinkable 100 years earlier.
The Vikings treated their mortal warriors with as much reverence as their deified ones, and this is evident in Norse mythology, particularly with the tale of Balder. This god of light was killed by a "dart of mistletoe" thrown by the mischievous Loki, resulting in "the greatest misfortune ever to befall gods and men" (Snorri Sturluson, Prose Edda). Balder was afforded a lavish ship burial, as recorded in the Prose Edda.
Epics and sagas were tales of pride and grandeur. Naval power, perfected early by Norsemen, had an exceptional place in these tales, and continued to be used in Christian narratives after the Conversion. There is not a great deal in the way of iconographic evidence for the earliest period of boat building by the Nordic people, but the record does increase from about the 11th century AD until the end of the Viking era. There is also literary evidence, present in many heroic sagas, of the abundance of Viking exploration and acquisition of land, beginning in about the 9th century. The most valuable evidence, however, undoubtedly comes from archaeology.
In archaeological terms, the survival of a boat burial depends entirely upon the soil in which it was interred. For example,soil that surrounded the early 7th century AD find at Ladby is highly acidic,thus all that remained of the original vessel were the rivets in a ghostly outline. Nevertheless, this, combined with previous knowledge of Viking boat construction, sagas, and other finds, allows us to determine how the ships were made.
The Nydam boat, found in 1863 in Southern Jutland, dates from the fifth century and is a precursor of the characteristic long boat associated with the height of the Viking period. Previously, ships had been designed for both trading and warfare, but the Nydam boat, measuring 76 ft overall, shows characteristics that indicate that it was built primarily as a warship. This trend toward militarization of the ships would continue until its climax in the Gokstad ship. The Vikings also decorated their ships with fearsome figureheads. Norse ships were decorated with heads and forms of various creatures: On the sterns can be seen different faces of metal ornamented with silver and gold.
The Gokstad ship, found in 1880 in Sandefjorde, Norway, is 79 ft overall, double-ended, like all Nordic ships, with a high curving stem and stern posts. The remains of the mast fitting suggest that the original would have been about 42 ft high, making the ship rather powerful and swift in the water. The Gokstad ship was also recovered with shields attached to the gunwale, at the ready for the warriors on board. The technical perfection of this ship came as a result of a long tradition of experience and experiment that first yielded sailing ships suitable for the open seas about one hundred years before the Gokstad ship was even built.
The Ladby ship, believed to date from the 10th century, was unearthed in 1935 on Funen, Denmark. The wooden skeleton had disintegrated, leaving only an impression in the soil and rivets. From this feature, archeologists were able to determine that the vessel was 67.5 ft long and 9.5 ft wide, much smaller than the Gokstad ship, but closer in length-to-beam ratio (1∶7) for a fast-oared warship. Inside, a nobleman's body was found, together with 11 horses and several dogs. One of the nobleman's horses bore an elaborate harness. Many other artifacts were unearthed, including a game board, arrows and a shield.
The ship burial discovered in 1904 at Oseberg turned out to be the grave of a noble woman of sufficient status to warrant a very lavish burial. Apart from the boat, the grave also contained an assortment of artifacts including three sledges, a cart, a saddle and the remains of ten horses and two oxen, tents, beds and other domestic items that the Lady would need in her next life. The ship was most likely used as coastal transportation by the noblewoman,rather than a working ship or "modern" warship, but still embodies transitional features found in later ships.
By the beginning of the Viking period in the ninth century AD, the long ships, as they were called, were about eight meters in length, but there is one of a whopping 23 meters. Through the evidence found at ship-burial sites, and other grave locations, it is clear that there was a common belief among the Norse peoples in life after death—a continuation of existence in which death was only one chapter among many. It is also demonstrated that there was not only a continuing of life, but of social status—the most complex funerals were those of the most wealthy and powerful men, and this evidence comes not only from grave goods but from accounts such as those found in sagas and epics.
The introduction of Christianity to the northern realms of Western Europe did not eliminate the Viking way of life in its entirety. It obviously quelled the more pagan practices, yet it is remarkable that saga literature, taken as a whole, did remain relatively unaffected by Christian norms. One may be tempted to suspect this was the result of an exceptionally faithful and tenacious tradition from the saga age. Vikings have always been portrayed as stubborn, determined and vigorous people—that their earlier ways of life should have survived the onset of Christianity it not surprising.
Questions 28-35
Classify the following descriptions as referring to
The Nydam shipN
The Gokstad shipG
The Ladby shipL
The Oseberg shipO
Write the appropriate letters in boxes 28-35 on your answer sheet.
NB You may use any answer more than once.
28. was probably not used for long ocean voyages.
29. had completed rotted away, leaving only an outline.
30. was probably used by a lady of high rank.
31. had warriors, shields still attached to its sides.
32. contained the remains of dogs.
33. had a mast about 42 ft high.
34. shows the beginning of the evolution of Viking ships from those meant for both trading and warfare to those used exclusively as warships.
35. provides evidence that the Vikings enjoyed board games.
Questions 36-40
Do the following statements agree with the information given in Reading Passage 3? In boxes 36-40 on your answer sheet write
YES if the statement agrees with the information
NO if the statement contradicts the information
NOT GIVEN if there is no information on this in the passage
36. The only evidence for ship burial is archeological.
37. Ships pervaded all aspects of Viking culture.
38. The Norse sagas give the locations of ship burials.
39. The Vikings stopped the practice of ship burial when they became Christians.
40. The buried ships found so far are intact.
Academic Reading Test 7
INTERNATIONAL ENGLISH LANGUAGETESTING SYSTEM
ACADEMIC READING
TEST 7
TIME ALLOWED:
NUMBER OF QUESTIONS:
1 hour40
Instructions
ALL ANSWERS MUST BE SRITTEN ON THE ANSWER SHEET
The test is divided as follows
Reading Passage 1 Questions 1-14
Reading Passage 2 Questions 15-25
Reading Passage 3 Questions 26-40
Start at the beginning of the test and work through it. You should answer all the questions. If you cannot do a particular question leave it and go on to the next. You can return to it later.
READING PASSAGE 1
You should spend about 20 minutes on Questions 1-14, which are based on Reading Passage 1.
Psychological Experiments on the Internet
In the last few years, it has become possible to conduct meaningful behavioral research via the Internet. As of June 17, 1998, there were 35 Internet experiments and surveys on the American Psychological Society list of Psychological Research on the Net. By May 11, 1999, this figure had grown to 65, suggesting a growth rate of about 100% per year. The experiments listed on the APS Web site ranged from 24 in social psychology, through 13 in cognitive psychology, eight in sensation/perception psychology, 2 in emotions, and one in general psychology.
Early pioneers of Internet research soon learned that it was not only possible to conduct research this way, but that it was also feasible to collect large samples of high-quality data in a short period of time. One advantage of Web-based research is the ease with which another researcher can see exactly what the participants experienced and also learn how the experimenter carried it out.
Because the Internet provides a means of reaching large and diverse samples, it seems ideally suited for the purposes of psychological research. Moreover, advanced computer techniques are now available that allow for greater control of Internet experiments. These include the dynamic creation and display of graphics, randomization and timing in experiments such as those in cognitive experimental psychology. In 1995, several developments (Java, JavaScript, HTML 2 with forms) combined to facilitate Web research. Psychologists now agree that experiments that were traditionally done by paper-and-pencil methods can be easily conducted using the technique of forms available in HTML (Hyper Text Markup Language).
Whereas laboratory studies typically use a small, homogeneous sample tested in controlled conditions, the Internet study typically uses a large, heterogeneous sample tested in less well-controlled conditions. The trend emerging from the early research on this problem is that Internet studies yield the same conclusions as studies done in the lab. Indeed, some psychologists argue that one should be more skeptical of traditional laboratory research than of Web-based research, because of certain problems inherent in traditional research. For instance, because large and diverse samples are obtained from the Web, one can separately analyze a research question in each demographic sub-sample, to ensure that conclusions that are found with 19-year-old college students also hold good for other demographic groups.
An important approach to validity is the use of criterion groups. For example, a test of mental illness should distinguish people who are patients in mental institutions from those who work there. Natural criterion groups exist in the form of subscribers to contrasting newsgroups on the Web. People who choose to join different groups should differ systematically in specific aspects of their personalities.
An additional advantage is that the Internet makes an experiment available to people from all parts of the world. Pagani and Lombardi took advantage of this new opportunity to conduct a cross-cultural examination of perceptions of the expression of surprise depicted in schematic faces. By manipulating features in schematic faces, they were able to change judgments of the degree of surprise. For people of all cultures, a general expansion of the features of the upper face produced higher judgments of degree of surprise. Interestingly, there were differences in judgment that are correlated with the culture or region of the participants. North Americans and North Europeans gave very similar judgments, but these differed from those of from Asians, who appeared to give relatively more weight to the eyes than the eyebrows. Southern Europeans gave results that are intermediate between those of Asians and North Europeans.
Mueller, Jacobsen and Schwarzer have asked if experiences in controlling a computer are correlated with greater self-efficacy. Perhaps people who learn that by following a scheme they can control a computer also learn that they can control other aspects of their lives. The Internet is a good place to study people who either have or have not learned to program, according to Mueller et al. Besides, the Internet also allows one to collect large samples in which small correlations can be detected, they found.
Questions 1-2
According to the information in the reading passage, select the most appropriate of the given options (A-D). Write the appropriate letter for each question in boxes 1-2 on your answer sheet.
1. Psychologists have found that the Internet...
A is inferior to the laboratory for research purposes
B enables them to expand the scope of their research
C helps people gain control over their lives
D knits together the international psychology community
2. Criterion groups formed on the Web....
A help psychologists identify personality types
B provide clues to the causes of mental illness
C have never been studied by psychologists before
D are usually mixtures of different types of people
Questions 3-8
In questions 3-8, complete each sentence by choosing one of the possible endings from the list below which best reflects the information in the reading passage. Write the corresponding letter (A-K) for each question in boxes 3-8 on your answer sheet. Note that there are more choices than spaces, so you will not use all of the choices.
The first one has been done for you as an example.
Example Answer
The American Psychological Society's Net list...H
3 Behavioral research via the Internet.....
4 The Internet makes it easy...
5 Advanced computer techniques...
6 Internet studies show the same results...
7 Cultural differences were found...
8 The degree of computer control may ....
List of possible endings
A in perceptions of the expression of surprise
B among groups surveyed on the Web
C is currently doubling every year
D have made paper-and-pencil techniques obsolete
E to collect large samples of data
F as those done in the lab
G is becoming meaningful in recent years
H show little interest in general psychology
I give researchers better control over Internet experiments
J the work of other psychologists
K indicate the level of self-efficacy
Questions 9-13
The paragraph below is a summary of the reading passage. Complete the summary by choosing NO MORE THAN THREE WORDS from the passage to fill each space. Write your answers in boxes 9-13 on your answer sheet.
Example Answer
it has become possible to conduct meaningful behavioral
research...
One difference between laboratory studies and Internet research is that the latter uses .......9.......data. As a result, some psychologists are becoming out the traditional approach to psychological experimentation. They say that the Internet makes it easier to make comparisons oups. Pagani and Lombardi tested reactions to expressions of surprise using computer-created........12.........Mueller, Jacobsen and Schwarzer found that the large amount of information yielded by the Internet enabled them to identify........13........
Question 14
In your view, the writer of the reading passage thinks that psychologists..........
A are wary of the Internet as a research tool
B will abandon traditional research methods
C see great potential for their work in the Internet
READING PASSAGE 2
You should spend about 20 minutes on Questions 15-25 which are based on Reading passage 2.
Ice Fishing for Space Clues
Deep inside a glacier at the South Pole, the world's most unconventional telescope is facilitating a new kind of astronomy based not on light but on neutrinos, ghostly particles that emerge from some of the most violent phenomena in the universe — supernovas and quasars. The Antarctic Muon and Neutrino Detector Array—AMANDA for short—has no mirror, no eyepiece, and no dome. Instead, it consists of about 700 bowling-ball-sized glass sensors that pick up the faint blue flashes given off when neutrinos collide with atoms more than a mile down in the Antarctic ice.
With no electrical charge and little mass, neutrinos zip through the universe largely unimpeded by gravity or magnetic fields, passing blithely through stars, planets, and your body. But one time in a billion a passing neutrino will strike a proton. The collision ejects a heavy electron, or muon, that travels in the same direction as the neutrino and leaves a trail of blue light as it sheds energy, much like a meteorite burning up in the atmosphere. AMANDA's photoreceptors absorb that telltale blue flash, turning the light into a measurable and meaningful electrical signal. A computer then compares the signals from several photoreceptors to calculate the path of the light streak in three dimensions. From that, scientists have a good idea of the neutrino's point of origin.
"The muon tells us the direction the neutrino came from, and then we have a telescope, because you can trace the neutrino back up into the sky," says Francis Halzen, a physicist at the University of Wisconsin at Madison. Because neutrinos barely interact with matter, they reach Earth still carrying unadulterated information about the cosmic events that produced them. Photons of visible light, in contrast, can get absorbed, obscured, and altered by intervening matter on its way to Earth. "Photons are very gregarious. They interact with everything they come into contact with on their way to Earth. Only neutrinos can bring us unvarnished information," said Robert Morse, Halzen's colleague at Wisconsin and AMANDA's project leader.
Just finding neutrinos is not good enough—it's the rare, very energetic ones that Morse and Halzen are after. But Earth is constantly showered with a far greater abundance of low-energy neutrinos generated in the sun or created when cosmic rays strike atoms in the upper atmosphere. Scientists have built giant underground water tanks to detect these solar neutrinos. But even the largest of these neutrino observatories—the 12.5-million-gallon Super Kamiokande in Japan—is too small to catch the few high-energy neutrinos.
Since it is prohibitively expensive to build a sufficiently large tank of water, physicists Halzen and Morse pursued a suggestion from a glaciologist: Look for neutrinos in the vast expanses of ultra-clear ice in Antarctica. At depths greater than about three-quarters of a mile, the pressure inside the glaciers squeezes out air bubbles, creating an extremely transparent medium in which a photon of light travels an average of 700 feet before being absorbed. Down there, the ice is bathed in a continuous blue glow from millions of sparking muons. The primary task of the AMANDA sensors is to study this glow and track how the muons travel through the ice. All the downward-moving muons come from low-energy neutrinos created in the atmosphere above the South Pole. The interesting ones will be those moving upward, which are mostly more energetic particles originating from the sun or from somewhere far beyond the solar system. The intensity of each blue flash reveals the energy of the neutrino that produced it.
So far, AMANDA has successfully detected and tracked the background of low-energy neutrinos from the sun. To pick up the long-sought high-energy particles from intergalactic space, Morse and his Wisconsin colleagues are adding 5,000 sensors to transform AMANDA into IceCube. At 3,000 feet in each dimension, IceCube will be the largest single scientific instrument ever built. Finding even a handful of neutrinos from quasars and their ilk could allow the first direct measurement of the massive, galaxy-shaping, star-swallowing "black holes" believed to lieat the center of these celestial bodies. "The hope is that a particle that is almost nothing may tell us everything about the universe," says Halzen.
Adapted from an article by Tim Stoddard in Discover magazine
Questions 15-16
15 According to the passage, AMANDA differs from ordinary telescopes because it does NOT observe .... ......
16 What do you think is the main purpose of the passage?
A To publicize the University of Wisconsin.
B To warn about the danger of man interfering with Antarctica.
C To describe a possible breakthrough in astronomy.
D To expose the mistakes of earlier astronomers.
Questions 17-21
Complete the sentences, selecting the most appropriate word or words from the list below. Write the corresponding letters (A-J) in boxes 17-21 on your answer sheet.
Neutrinos originate in ..17...and ...18....
They have zero...19...
Their paths are identified by observing...20...
The blue flashes are picked up by AMANDA's...21...
supernovas the South Pole muons magnetic fields telescop photoreceptors electricity energy computer quasars
Questions 22-25
Choose which of the options (A-D) best represents the information in the reading passage. Write the appropriate letter for each question in boxes 22-25 on your answer sheet.
22. Photons are unsuitable for studying space phenomena because...
A they cannot be trapped in ice
B they do not originate in violent phenomena
C they are visible to the naked eye
D they interact with everything they come into contact with on their way to Earth
23. The value of neutrinos to scientists is that...
A they bring pure information about the universe
B they can be measured more accurately than photons
C they are high-energy articles
D they are soluble in ice
24. The deep ice in Antarctica is made highly transparent by...
A extreme cold
B blue light from muons
C the elimination of air bubbles
D lack of pollution
25. Ice Cube will be unique because...
A it will have 5,700 sensors
B it will be the biggest single scientific instrument ever built
C it will be the only scientific instrument in Antarctica
D it will detect both high-and low-energy neutrinos
READING PASSAGE 3
You should spend about 20 minutes on Questions 26-40 which are based on Reading
Passage 3.
Fiber Optics Promises Unlimited Network Capacity
Engineers and scientists agree that the only transmission medium that could come close to meeting the seemingly infinite demand for more space in international communications is optical fiber. Fiber links can channel hundreds of thousands of times the bandwidth of microwave transmitters or satellites, the nearest competitors in long-distance communications.
The race to augment the fiber content of the world's networks has started. Every day, installers lay enough new cable to circle the earth three times. If improvements in fiber optics continue, the carrying capacity of a single fiber may reach hundreds of trillions of bits a second just decade or so from now.
New photonic technologies, which use light waves instead of electrons for signal processing, will make current electronic switching systems obsolete. Even now the transmission speeds of the most advanced networks—at 10 billion bits a second—threaten to choke the processing units and memory of microchips in existing switches. As the network becomes faster than the processor, the cost of using electronics with optical transmissions is skyrocketing. The gigabit torrent contained in a wavelength of light in the fiber must be broken up into slower-flowing data streams that can be converted to electrons for processing—and then re-aggregated into a fast-flowing river of bits. The equipment for going from photon to electron and back to photon not only slows traffic on the superhighway, it makes equipment costs soar.
Besides lower transmission costs, optical fiber solutions have the added advantages of bigger bandwidth capacity and the potential of full integration of voice, video and data services. While network designers contemplate the prospect of machine overload, hundreds of companies, big and small, now grapple with creating networks that can exploit fiber's full bandwidth by transmitting, combining, amplifying and switching wavelengths without ever converting the signal to electrons. Photonics is at a stage that electronics experienced 30 years ago—with the development and integration of component parts into larger systems and subsystems. Investment in optical communications already yields payoffs, as the cost of transmitting a bit of information optically halves every nine months, as against 18 months to achieve the same cost reduction for a circuit integrating photonics and electronics. "Because of dramatic advances in the capacity and ubiquity of fiber-optic systems and subsystems, bandwidth will become too cheap to measure," predicts Arun Netravali, president of Lucent Technologies' Bell Laboratories in a recent issue of Bell Labs Technical Journal.
Today some fibers are pure enough that a light signal can travel for about 80 kilometers without the need for amplification. But at some point the signal still needs to be boosted. The next significant step on the road to the all-optical network came in the early 1990s, a time when the technology made astounding advances. It was then that electronics for amplifying signals were replaced by stretches of fiber infused with one of the rare-earth elements known as erbium. When these erbium-doped fibers were zapped by a pump laser, the excited erbium ions could revive a fading signal. This process restores a signal without any optical-to-electronic conversion and can do so for very high speed signals sending tens of gigabits a second. Perhaps most important, however, it can boost the power of multiple wavelengths simultaneously.
This ability to channel multiple wavelengths expands the capacity of the fiber by the number of wavelengths, each of which can carry more data than could be handled previously by a single fiber. Nowadays it is possible to send 160 frequencies simultaneously, supplying a total bandwidth of 400 gigabits a second over a single fiber. Every major telecommunications carrier is now using this technique to increase the capacity of the fiber that is already in the ground, spending less than half of what it would cost to lay new cable, while the equipment gets installed in a fraction of the time it takes to dig a hole.
In this new photonic world, any type of traffic, whether voice, video or data, may travel as IP (Internet Protocol) packets. A development heralded in telecommunications for at least 20 years—voice, video and data services all at the same time—will be complete. And all because of the miracle of optical fiber.
From an article by Gary Stix in Discover magazine
Questions 26-28
Read the following statements and say how they reflect the information in the reading passage by writing
T if it is true according to the passage,
F if it is false according to the passage, and
NG if the information is not given in the passage.
Write your answers in boxes 26-28 on your answer sheet.
26 There is a limit to the demand for international communications capacity.
27 Electronic switching systems will soon be discarded.
28 Satellites can be used to transmit optical signals.
Questions 29-34
The paragraph below is a summary of the first part of the reading passage. Complete the summary by choosing NO MORE THAN THREE WORDS from the reading passage to fill the spaces 29-34. Write the words in boxes 29-34 on your answer sheet.
Example Answer
A race has started to increase the fiber content of
telecommunications networks worldwide
Experts are of the opinion that n meet the demand for expansion of the carrying capacity of international communications links. The bottleneck at present is the use of ...30..., which is also sending costs...31...Companies are now working on ways to modify light signal wavelengths without changing the signals into...32... and back again. Electronics is being overtaken by...33..., as investment in the latter is already producing...34...
Questions 35-37
Give three factors which are responsible for increasing interest in optical fiber as a transmission medium. Write NO MORE THAN THREE WORDS for each factor in boxes 35-37 on your answer sheet.
Questions 38-40
Match the items below with the appropriate definition A-F
