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A major radio outburst in III Zw 2 with an extremely inverted, millimeter-peaked spectrum

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a rXiv:as tr o-ph/991375v127Jan1999A major radio outburst in III Zw 2with an extremely inverted,millimeter-peaked spectrum Heino Falcke 1,7,Geoffrey C.Bower 1,2,Andrew P.Lobanov 1,Thomas P.Krichbaum 1,Alok R.Patnaik 1,Margo F.Aller 3,Hugh D.Aller 3,Harri Ter¨a sranta 4,Melvyn C.H.Wright 5,G¨o ran Sandell 6ABSTRACT III Zw 2is a spiral galaxy with an optical spectrum and faint extended radio structure typical of a Seyfert galaxy,but also with an extremely variable,blazar-like radio core.We have now discovered a new radio flare where the source has brightened more than twenty-fold within less than two years.A broad-band radio spectrum between 1.4and 666GHz shows a textbook-like synchrotron spectrum peaking at 43GHz,with a self-absorbed synchrotron spectral index +2.5at frequencies below 43GHz and an optically thin spectral index −0.75at frequencies above 43GHz.The outburst spectrum can be well fitted by two homogenous,spherical components with equipartition sizes of 0.1and 0.2pc at 43and 15GHz,and with magnetic fields of 0.4and 1Gauss.VLBA observations at 43GHz confirm this double structure and these sizes.Time scale arguments suggest that the emitting regions are shocks which are continuously accelerating particles.This could be explained by a frustrated jet scenario with very compact hotspots.Similar millimeter-peaked spectrum (MPS)sources could have escaped our attention because of their low flux density at typical survey frequencies and their strong variability.Subject headings:Galaxies:active—Galaxies:individual:III Zw 2—Galaxies:jets—Galaxies:Seyfert—acceleration of particles—quasars:general 1.Introduction III Zw 2(PG 0007+106,Mrk 1501,z=0.089)is an active galaxy with very unusual radio properties and extreme variability.The source was discovered by Zwicky (1967)and initially classified as a Seyfert galaxy (e.g.Arp 1968;Khachikian &Weedman;Osterbrock 1977)but was later also included in the PGquasar sample (Schmidt &Green 1983).The galaxy was classified as a probable spiral by Hutchings et al.(1982)which was later confirmed by fitting model isophotes to NIR galaxy images (Taylor et al.1996).The bolometric,optical-to-UV,luminosity for III Zw 2was estimated to be L UV ∼1045erg/sec (Falcke,Malkan,Biermann 1995;scaled to H 0=75km/sec/Mpc as used here).The most intriguing property of III Zw2,however,is its extreme variability at radio and other wavelengths.Schnopper et al.(1978)described the onset of a huge,four year long radio outburst which peaked around1980.A more detailed radio lightcurve of this outburst was presented by Aller et al.(1985); the source showed a twenty-fold increase in radioflux density,rising from about100mJy at8GHz to over 2Jy within four years.For comparison,the typical amplitude variability in Blazars like3C279is usually not much larger than a factor two or three.The source also shows optical(Lloyd1984)and x-ray variability (timescale less than a day;Kaastra&Korte1986;Pounds1986).Such a pattern of variability is usually associated with BL Lac objects and blazars,which are thought to be associated with radio galaxies within the unified scheme(e.g.Urry&Padovani1995).However,as Falcke et al.(1995;1996a&b)have pointed out,III Zw2clearly does notfit into these categories.Its time averaged radio-to-opticalflux density ratio R is of the order200(Falcke et al.1996a)which is significantly less than in typical blazars like3C273(R∼2000)and otherflat-spectrum radio quasars.Its extended radio flux density from parsec to kiloparsec scales consists of only a weak8mJy component at1.4GHz(Unger et al.1987)and hence cannot be associated with a typical radio galaxy.Radio spectrum and interferometer observations also rule out a Gigahertz-Peaked-Spectrum(GPS)or Compact-Steep-Spectrum(CSS)source which are considered to be predecessors of giant radio galaxies(O’Dea1998);the structure as measured with VLBI and MERLIN is point-like(Falcke et al.1996b;Kellermann et al.1998).The shape and luminosity of the extended radio emission,and the host galaxy type are rather typical for a Seyfert galaxy and it has therefore been suggested that III Zw2could be a‘weak blazar’in a Seyfert galaxy or radio quiet quasar,i.e.an intrinsically radio weak,yet relativistic jet pointing towards the observer.Falcke et al.(1995&1996a)have identified a number of similar sources,named radio-intermediate quasars(RIQs),which might indeed form such a class of‘weak blazars‘.To test this hypothesis we have started to watch III Zw2more carefully.In the beginning of1998it became clear that III Zw2would show another major outburst and we launched a number of observational projects to study the radio evolution of this outburst and here report ourfirst results.2.Observations&Results2.1.Radio lightcurvesIII Zw2was re-entered into the radio-flux monitoring program at Michigan(Aller et al.1985)in1997 May(observations previously ceased at the end of1995)and thereafter was observed every few days at4.8, 8,and14.5GHz.The15GHzflux density rose linearly since then while the8and4.8GHzflux density levels remained low,indicating an inverted spectrum.In addition,III Zw2was also monitored at22and37 GHz at the Mets¨a hovi Radio Research Station(MRRS;e.g.Ter¨a sranta,H.et al.1992)over more than ten years.The results are shown in Figure1,where we have plotted the radio light curve at22GHz up until 1998September.The most recent rise of theflux density is very obvious without any sign of a slow-down of theflare.Its magnitude indicates the advent of a major outburst.A more detailed discussion of the lightcurves will be given in a later paper.2.2.Radio spectrumIn addition to the available monitoring data,we used the Very-Large-Array(VLA),the Effelsberg 100m telescope,the BIMA array,and the James-Clerk-Maxwell-Telescope(JCMT)to obtain a reliable and almost simultaneous broad-band radio spectrum of III Zw2extending over two and a half decades in frequency from1.4to660GHz.The VLA observations were made in A-configuration on1998May21simultaneously in L(1.465GHz) and P(350MHz)band with a total integration time of24mins.3C48was used as the primaryflux density calibrator and III Zw2was self-calibrated and mapped with AIPS.At1.4GHz wefindflux densities of44 mJy for the core and8mJy for an extended,lobe-like component15′′to the SW.A heavily tapered map reveals a possible bridge between core and lobe.The core also has a weak extension towards the west.The core and the lobe are also seen at350MHz where they are both point-like.Because the amplitudes of the interferometer data at350MHz were corrupted by interference,an absoluteflux-estimate was not possible. Nevertheless,we can infer from the data that the lobe-to-core ratio at350MHz is0.5,consistent with aflat core and a steep lobe spectrum(e.g.for a typical,yet at this stage completely arbitrary,spectral index of α=−1(Sν∝να)for the lobe we would get a coreflux density of roughly65mJy).III Zw2was observed with the Effelsberg100m telescope on1998May16under very good weather conditions at2.7,4.9,10.5,14.6,23,32,&43GHz with cross scans(e.g.,Kraus1997).NGC7027was used as primaryflux density calibrator(Ott et al.1994).If we make a linearfit with time to the available monitoring data at15and22GHz,the predictedflux densities for this day differ from the Effelsbergfluxes by only1.3and2.5%respectively.High-frequency data for III Zw2were obtained on1998May20&24 with BIMA at70through110GHz and with JCMT at150,230,350,&666GHz on1998May27&28 using Uranus asflux density calibrator.The measuredflux densities at the various frequencies are plotted in Figure2with gray dots.The spectrum is highly inverted at cm wavelengths,with a spectral index as high asα=+1.9±0.1between4.8 and10.5.The spectral turnover is around43GHz.Someflattening of the spectrum can be seen towards lower frequencies.At frequencies above43GHz the spectrum becomes steep with a spectral index around α=−0.75±0.15.2.3.SpectralfittingWith the available broad frequency coverage we are able to decompose the spectrum into its various components.The spectral shape is clearly indicative of an almost homogenous,spherical synchrotron source which becomes self-absorbed below43GHz and is optically thin at high frequencies.For such a blob where Sνis the observedflux density,D is the distance from the observer,d is the diameter of the blob,andκsync andǫsync are the synchrotron absorption and emission coefficients,the observed spectrum will be given by a simple radiative transfer equation(e.g.Rybicki&Lightman1979)Sν=d2κsync 1+e−dκsync ddκsyncand B0is the magneticfield in Gauss.In addition to this synchrotron-spectrum we have to take into account the quiescent spectrum ofIII Zw2on which the outburst spectrum is superposed and which most likely leads to theflattening of the spectrum at lower frequencies.For simplicity we assume aflat spectrum(α=0).This is indicated by earlier post-flare data and is quite typical for central cores in AGN in quiescence.We derive a quiescentflux density level of∼40mJy,from satisfying the requirement that the outburst spectrum in the self-absorbed part continues as a power-law after subtraction of the quiescent spectrum.This quiescentflux density is consistent with the350MHz data and earlier VLAflux observations at8GHz in1992October by Browne et al.(1998)near aflux density minimum of III Zw2.The pure outburst spectrum after subtraction,shown in Fig.2as black dots,can be wellfitted by a two-component model.If we ignore relativistic boosting for now(see Sec.3.3),least-squaresfitting of the synchrotron spectrum(Fig.2,solid line)then provides an estimate for the diameters and magneticfields involved.Wefind with our equipartition assumption d=120µas&B=0.5Gauss for the lower-frequency component and d=50µas&B=1.3Gauss for the higher-frequency component.We note that inclusion of relativistic boosting with typical Lorentz factors of a few would only change these numbers by a factor ofa few.2.4.VLBA observationsFollowing the onset of the outburst we activated a VLBA target-of-opportunity program to monitor the structural evolution of the source.Afirst epoch observation was made on16February1998at43and15 GHz.We observed with a total bandwidth of64MHz for a full8hour scan,where we spent three quarter of the available observing time at43GHz and one quarter at15GHz.We reduced the data using the software packages AIPS and DIFMAP(Shepherd,Pearson,&Taylor1994).Fringes were detected in the III Zw2data on all baselines.We calibrated the gains using system temperature information and applied atmospheric opacity corrections.The amplitude gains for the stations at Brewster,North Liberty,and Pie Town were ignored for the absolute amplitude calibration.The data were then self-calibrated and mapped.For naturally weighted maps we obtained dynamic ranges of2000:1at43GHz and5000:1at15GHz.Down to respective3σlevels of1.3mJy and0.4mJy no additional components besides the central core were detected.The core itself is resolved at43GHz,where the visibilities drop to one third at1200Mλ.It is only marginally resolved at15GHz.At43GHz wefind a totalflux density of1.6±0.1Jy consistent with the totalflux density1.7±0.1Jy for the source from the monitoring data.An ellipticalfit to the UV data gives a source size(FWHM)of90µas×60µas at PA -76◦,yielding a brightness temperature of3×1011K.This elongated structure can also been seen in the super-resolved map with a circular beam of0.1mas shown in Figure3(the nominal beam is350×130µas at PA−7◦).Thefitted spherical source size at15GHz is100±50µas for a totalflux density of0.7Jy,giving a brightness temperature of5×1011K.The closure phases at long baselines for the43GHz data show a significant deviation from zero indicating an asymmetric structure.The non-zero closure-phases are wellfit by a two-component model of a stronger core component(1±0.3Jy,50±15µas)and a weaker secondary component(0.6±0.3Jy,65±30µas) separated by65±30µas at PA75◦±10◦.3.Summary and Discussion3.1.Self-absorbed synchrotron spectraBecause the current outburst spectrum of III Zw2dominates almost the entire radioflux density,we have the unique opportunity to study the spectrum and evolution of such aflare over a wide frequency range with low resolution.In typical AGN radioflares the spectrum is much more confused by multiple components so that VLBI techniques have to be used to separate them,providing only very small frequency coverage because of the frequency dependent resolution of the telescopes,and resulting blending of the components.Hence,ourfirst epoch spectrum for III Zw2already provides a nice confirmation of very basic synchrotron theory,giving a spectrum with a textbook-like shape for the outburst component:starting in the optically thick regime with a spectral index approaching its maximal value ofα=+2.5it turns over into the optically thin regime with the typical spectral index ofα=−0.75.Moreover,the diameters we obtain from the spectralfitting assuming equipartition are consistent with those we actually measure with the VLBA.3.2.Variability,cooling,and particle accelerationSince the current outburst has begun in the beginning of1997,the22GHzflux density of III Zw2 has risen within∼600days by at least a factor of20.Even compared to blazars this variability amplitude is extreme;for example the dramatic millimeterflare in NRAO530(Bower et al.1997)had an almost ten times lower(relative)amplitude.From the relation for the characteristic frequencyνc=34GHz (B/Gauss)(γe/100)2and with our magneticfield estimate of1Gauss we calculate that the typical electron Lorentz factor at43GHz isγe=100and at our highest frequency666GHz isγe=390.The synchrotron cooling time scales t sync=7.7·106sec(B/Gauss)−2(γe/100)−1at these energies are only50and14days respectively and hence are much shorter than the duration of the current outburst.This directly implies that the region of enhanced emission must also be a region of very efficient in-situ particle acceleration.Since the measured brightness temperature is very close to the Compton limit(a few times1011K, Readhead1994)and if relativistic boosting can be ignored(see next section)it is likely that inverse Compton cooling of the relativistic electrons is important.This could lead to non-thermal optical and X-ray emission and could explain the variability in these wavebands as seen in earlier outbursts.3.3.Jet nature and expansion velocityAnother interesting question of course is what the nature of this core actually is.As speculated in Falcke et al.(1996a&b)theflat quiescent spectrum measured in the past indicates a similarity to nuclear jets found in other AGN.This notion is strengthened by the slightly elongated structure found at VLBI scales,the faint extension of the core seen at a similar PA in the VLA map at1.4GHz,and the presence of a lobe-like feature15′′to the SW.Influx density and morphology the latter is rather typical for lobes associated with Seyfert jets(e.g.Mrk34or Mrk573;Falcke,Wilson,Simpson1998).Assuming that one or both components were ejected at or before the onset of theflare,we can calculate an upper-limit to the expansion velocity of the ing the duration of the outburst(600days)asthe time scale and the component separation(0.1pc)of the components at43GHz as the size scale we calculate a characteristic velocity,i.e.expansion velocity,of∼<0.2c.This could either mean a sub-luminal jet speed or a strong shock in an initially relativistic jet with a speed≫0.2c as proposed by Falcke et al.(1996a&b).The relativistic shock scenario seems to be more likely since we have already shown above that particle acceleration is actually taking place.In fact,the shocks could be similar to hotspots in radio galaxies or GPS/CSS sources.Such a scenario also would justify neglecting relativistic boosting in Sec.2.3.The highly inverted spectrum of III Zw2at GHz frequencies points into a similar direction.We know that such spectral shapes at lower frequencies mainly originate from CSS and GPS sources,where the spectrum is dominated by jets and hotspots on scales much smaller than the galaxy.Hence,one is tempted to call III Zw2a millimeter-peaked-spectrum(MPS)source,possibly containing ultra-compact hotspots and operating on very short timescales compared even to GPS sources.If other,similar MPS sources exist, they might have easily escaped current low-frequency radio surveys and could become important targets for mm-VLBI experiments.3.4.ConclusionIII Zw2remains a puzzle.Its radio core luminosity during outburst is very high(∼4·1043erg/sec at350GHz,which is comparable to the radio luminosity of Cygnus A),yet it is apparently located ina spiral galaxy.Moreover,its quiescentflux density and extended structure makes it look more like a Seyfert galaxy or radio-quiet quasar.An initially relativistic radio jet,strongly interacting with dense ISM at the sub-pc scale,thereby producing an intense shock(hotspot)and slowing down the jet considerably could be a possible explanation.Because of the simplicity of the source and its very low quiescent level, monitoring of the spectral and structural evolution of the outburst will help to test this or other scenarios and may teach us something about the general nature of radioflares,their expansion speeds,and their connection to particle acceleration.To achieve this,additional monitoring of this outburst at optical and x-ray wavelengths would be highly desirable.This research was supported by DFG grants Fa358/1-1&2and by NSF Grant AST-9613998tothe University of California,Berkeley.The BIMA array is operated by the Berkeley-Illinois-Maryland Association under funding from the National Science Foundation.This research has made use of data from the University of Michigan Radio Astronomy Observatory which is supported by the National Science Foundation and by funds from the University of Michigan.The National Radio Astronomy Observatory is a facility of the National Science Foundation,operated under a cooperative agreement by Associated Universities,Inc.REFERENCESAller,H.D.,Aller,M.F.,Latimer,G.E.,&Hodge,P.E.1985,ApJS59,513Arp,H.1968,ApJ152,1101Bower,G.C.,Backer,D.C.,Wright,M.,et al.1997,ApJ484,118Browne,I.W.A,Patnaik,A.R.,Wilkinson,P.N.,Wrobel,J.M.1998,MNRAS293,257Falcke,H.,Malkan,M.,&Biermann,P.L.1995,A&A298,375Falcke,H.,Sherwood,W.,&Patnaik,A.1996a,ApJ471,106Falcke,H.,Patnaik,A.,&Sherwood,W.1996b,ApJ473,L13Falcke,H.,Wilson,A.S.,&Simpson,C.1998,ApJ502,199Hutchings,J.B.,Campbell,B.,Gower,A.C.,et al.1982,ApJ262,48Kellermann,K.I.,Vermeulen,R.C.,Zensus,J.A.,Cohen,M.H.1998,AJ115,1295Kraus,A.1997,PhD thesis,RFW University BonnKaastra,J.S.,&de Korte,P.A.J.1988,A&A198,16Khachikian,E.Ye.,&Weedman,D.W.1974,ApJ192,581Lloyd,C.1984,MNRAS209,697O’Dea,C.P.1998,PASP110,493Osterbrock,D.E.1977,ApJ215,733Ott,M.,Witzel,A.,Quirrenbach,A.,et a.1994,A&A284,331Pounds,K.A.1986,in Conf.Proc.“Variability of Galactic and Extragalactic X-ray Sources”,ed.A.Treves, Cuomo,Italy,p.1Readhead,A.C.1994,ApJ,426,51Rybicki,G.B.,&Lightman,A.P.1979,“Radiative Processes in Astrophysics”,John Wiley&Sons Inc., New YorkSchmidt M.,&Green R.1983,ApJ269,352Schnopper,H.W.,Delvaille,J.P.,Epstein,A.,et al.1978,ApJ222,L91Shepherd,M.C.,Pearson,T.J.,&Taylor,G.B.1994,BAAS26,987Taylor,G.L.,Dunlop,J.S.,Hughes,H.,&Robson,E.I.1996,MNRAS283,930Ter¨a sranta,H.,Tornikoski,M.,Valtaoja,E.,et al.1992,A&A94,121Unger,S.W.,Lawrence,A.,Wilson,A.S.,Elvis,M.,&Wright,A.E.1987,MNRAS228,521Urry,C.M.,&Padovani,P.1995,PASP107,803Zwicky,F.1967,Adv.Astr.Ap.5,267Fig.1.—Long-term radio lightcurve of III Zw2at22GHz measured at Mets¨a hovi.Fig.2.—Broad-band radio spectrum of III Zw2.Gray dots show theflux densities measured between16May and28May1998,black dots show the outburst spectrum with the quiescent level of40mJy subtracted.The three solid gray lines represent the threefitted components(quiescent level and two self-absorbed synchrotron components),the black solid line is the resultingfit to the outburst spectrum(self-absorbed synchrotron components only)and the gray dashed line represents thefit to the total observed spectrum.Fig.3.—VLBA map of III Zw2at43GHz convolved with a beam of100µas.The gray dots represent the two-component modelfitting the non-zero closure phases.JD-2400000.5f l u x d e n s i t y [J y ]51050100500Frequency [GHz]0.010.11F l u x d e n s i t y [J y]–11–Center at RA 00 10 31.00587 DEC 10 58 29.5037Cont peak flux = 1.1724E+00 JY/BEAMLevs = 1.5000E-02 * ( -2.00, -1.40, -1.00, 1.000, 1.400, 2.000, 2.800, 4.000, 5.700,8.000, 11.30, 16.00, 23.00, 32.00, 45.00, 64.00)M i c r o A R C S E C MicroARC SEC-100-200-300-400。

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英语作文关于中国人民军事博物馆

英语作文关于中国人民军事博物馆

英语作文关于中国人民军事博物馆全文共6篇示例，供读者参考篇1My Trip to the Chinese People's Revolution Military MuseumLast weekend, my parents took me on a really cool trip to the Chinese People's Revolution Military Museum in Beijing. I was so excited because I love learning about history, especially military history with airplanes, tanks, and weapons!The museum is huge - it has an indoor exhibition hall that's several stories tall and a big outdoor area too with even more displays. As soon as we walked in, I was in awe at all the massive tanks, artillery, and other military vehicles everywhere. My dad said they were from different periods in China's history of defending itself.We started in the indoor section which had room after room of exhibits showing the revolutionary struggles of the Chinese people over the decades. There were lifesized dioramas recreating famous battles with realistic scenery and model soldiers. My favorite was the one about the Long March - itshowed the Red Army trekking across treacherous mountain paths while being attacked by enemies. So brave!Another exhibition chronicled the War of Resistance Against Japanese Aggression from 1937-1945. It was horrifying to learn about the atrocities committed by the invading Japanese forces. But it also filled me with pride seeing how courageously the Chinese people fought back until finally achieving victory. The displays included tanks, planes, and other equipment used during those battles.Upstairs, they had exhibitions about more recent conflicts that China was involved in. Like the Korean War in the 1950s when China came to the aid of North Korea against the United States and United Nations forces. And the Sino-Indian War in 1962 over border disputes. I saw bombers, helicopters, missiles and all kinds of advanced weaponry from those times. It's crazy how much military technology has developed over the years!My favorite part was definitely the outdoor grounds though. That's where they had the biggest specimens including the Qirassier, one of the largest artillery pieces ever made! It was taller than a three-story building. Nearby were rows of different tanks from across the decades, painted in camouflage colors. Icould have spent all day examining their turrets, treads, and cannons.To my delight, the museum also had a whole section dedicated to aviation with real aircraft on display. I marveled at the old Russian biplanes used by Chinese pilots to defend against Japanese invaders in the 1930s. And thrilled at the sight of sleek modern fighter jets with their swept-back wings and missile payloads. I could picture them soaring through the air at supersonic speeds!We finished our visit at an exhibit all about China's efforts in the Space Race and its taikonauts. I posed for a photo pretending to operate the controls inside a model of the Shenzhou spacecraft that has carried Chinese astronauts into orbit.Visiting the military museum was one of the highlights of my summer vacation. It gave me a deep appreciation for what generations of Chinese soldiers have sacrificed to protect our country throughout history. And it stoked my fascination with all things related to national defense like aircraft, artillery, missiles, and more. I can't wait to go back and explore all the cool weapon systems on display some more! Every kid who likes science,history, and high-tech military hardware should make sure to visit too.篇2My Trip to the Chinese People's Military MuseumLast weekend, my parents took me on a very exciting trip to the Chinese People's Military Museum in Beijing. I had been looking forward to this visit for a long time because I love learning about history, especially military history. The museum is huge, and it was hard to believe how many interesting things were inside!As soon as we entered the museum, I was amazed by the massive tanks, artillery pieces, and other military vehicles on display in the outdoor exhibition area. Some of them were so big that I could have easily fit inside! My dad told me that these were used in important battles during World War II and other wars that China has fought in. I couldn't wait to see what was inside the museum building.The first thing we saw when we went inside was a giant model of the famous Terracotta Warriors from Xi'an. Theselife-sized clay soldiers were buried with China's first emperor over 2,000 years ago to protect him in the afterlife. I had learnedabout them in school, but seeing them up close was incredible. They looked so lifelike and detailed, like real soldiers standing guard.Next, we went to the exhibition halls that covered different periods of Chinese military history. One hall was all about ancient China, with displays of old weapons like swords, spears, and crossbows. I saw a replica of a giant crossbow that could shoot multiple arrows at once! Another hall focused on the wars against Japanese invaders in the 1930s and 1940s. There were uniforms, equipment, and personal belongings of soldiers from that time. I felt sad looking at the photographs of the destruction and suffering caused by the war.My favorite part was the hall dedicated to modern times, especially the missiles, jets, and other high-tech military equipment used by China today. I was fascinated by the sleek designs and advanced technology. There were even real-size models of spacecraft and satellites used for military purposes. I could have spent hours examining all the buttons and controls in the cockpits of the fighter jets on display.Throughout the museum, there were also lots of interactive exhibits and multimedia displays that made learning about history fun. In one area, I got to try on a virtual reality headsetthat made me feel like I was right in the middle of an ancient battlefield, with arrows and swords flying all around me! In another section, I played a video game where I had to strategize and command troops during a famous historical battle.By the time we left the museum, my brain was filled with so much new knowledge about China's military history and achievements. I had a much better understanding of the sacrifices and bravery of Chinese soldiers throughout the centuries in defending the country. I also learned about the importance of military strength and advanced technology for national security.On the way home, I kept thinking about all the amazing things I had seen and experienced at the museum. I decided that when I grow up, I want to be a military engineer or designer so that I can help create the next generation of powerful weapons and equipment to keep China safe and strong. This trip really opened my eyes to the crucial role that the military has played in shaping China's past, present, and future.I can't wait to go back to the Chinese People's Military Museum again someday. There was so much to see and learn that I know I missed a lot on this first visit. Maybe next time, my parents will even let me try on one of the soldier uniforms or sitin the cockpit of a real fighter jet! Until then, I'll keep studying hard so that I can make my dream of working in the military a reality.篇3The Chinese People's Revolution Military MuseumHi everyone! Today I'm going to tell you all about my trip to the Chinese People's Revolution Military Museum in Beijing. It was so cool!The museum is huge, with loads of different exhibitions all about China's military history. When you first go in, there's a massive statue of soldiers marching that's really impressive. My little brother got a bit scared because the soldiers look very fierce!The first exhibition we went to was all about the revolutionary era before 1949 when the Communist Party fought against the Nationalists to take control of China. There were lots of old weapons and uniforms from that time on display. My篇4The China People's Revolutionary Military Museum: A Fascinating Journey Through History!Hi there, friends! I recently went on a super cool field trip to the China People's Revolutionary Military Museum in Beijing, and let me tell you, it was an adventure I'll never forget! This place is like a giant time machine that takes you on a journey through China's incredible military history.As soon as I stepped inside, I was greeted by massive tanks, fighter jets, and all sorts of amazing weapons and equipment. My jaw hit the floor! I felt like I had been transported to a real battlefield, but without any danger, of course. The museum is massive, with endless halls and exhibits to explore.One of my favorite parts was the section dedicated to ancient Chinese warfare. I got to see replicas of awesome weapons like crossbows, battle axes, and even catapults! Can you imagine how tough those ancient warriors must have been to use those things? I tried lifting a replica sword, and let me tell you, it was heavier than my backpack filled with books!But the coolest part, by far, was the exhibit on modern military technology. There were huge tanks with massive guns, fighter jets that looked like they came straight out of a movie, and even rockets and missiles! I felt like a tiny ant standing next to those massive machines. The guides at the museum werereally nice and explained how all the equipment worked, which was super fascinating.I also learned a lot about important battles and wars in Chinese history, like the Opium Wars, the Sino-Japanese War, and the Civil War. It was really interesting to see how the military strategies and techniques evolved over time. I even got to see actual uniforms and gear that soldiers wore during those conflicts. Imagine how uncomfortable those heavy uniforms must have been, especially in the hot summer!One thing that really stuck with me was the exhibit on the brave soldiers who fought for China's freedom and independence. It made me feel proud to be Chinese and grateful for the sacrifices those heroes made so that we could live in peace today. It was really moving to see their personal belongings and read their stories.Overall, my visit to the China People's Revolutionary Military Museum was an unforgettable experience. I learned so much about China's rich military history and the incredible men and women who have fought to protect our country. It's definitely a place I'd love to visit again someday, and I highly recommend it to anyone who's interested in history, technology, or just wants to have an awesome time!That's all for now, friends! Until next time, keep exploring and learning about the amazing world around us!篇5My Trip to the Chinese People's Revolutionary Military MuseumLast weekend, my parents took me and my little brother to visit the Chinese People's Revolutionary Military Museum in Beijing. I was really excited because I love learning about history, especially military history. My brother wasn't too thrilled, but I promised to share my comic books with him if he behaved.The museum is huge! It's made up of several buildings and has so many exhibitions inside. We started our tour in the main exhibition hall, which is shaped like a huge cross. There were all kinds of cool military vehicles, weapons, and equipment on display. My favorite was probably the tanks - they were massive!One of the first things we saw was a model of the famous Xibaipo Village where the Communist Party was based during the revolutionary war against the Japanese invaders and the Nationalist government. There were little figurines set up to show what life was like for the soldiers living there. It lookedreally tough, but they never gave up fighting for China's freedom.Next, we walked through galleries covering theAnti-Japanese War from 1937 to 1945. There were blown up Japanese tanks and planes, along with captured artillery and small arms. One section had wax statues recreating famous battles like the Defense of Sihang Warehouse. Seeing the faced expressions on the Chinese soldiers was really powerful.My brother especially liked the displays of swords, grenades, and machine guns used by both sides. He kept asking our dad questions like "Can this one blow off someone's arm?" Which kind of grossed me out. But I have to admit, the weaponry was fascinating in a way.After that we explored the Civil War period between the Communists and Nationalists from 1945 to 1949. This part really emphasized how determined and well-organized the Communist forces were under leaders like Mao Zedong. There were dioramas portraying major campaigns like the Huaihai Battle and the Beijing & Tianjin Campaign. Seeing the Nationalists surrendering was pretty sad though.One of my favorite sections covered the War to Resist U.S. Aggression and Aid Korea from 1950 to 1953. China bravelystood up to the mighty American military to defend its ally North Korea. The displays included the burnt-out remains of a U.S. bomber shot down by Chinese anti-aircraft guns. There were also recordings of Chinese "Volunteer Army" soldiers describing brutal combat against the Americans.My brother got bored during this part and said "Can we please go soon? My feet hurt." But I kept him interested by showing him guerilla gear like punji stake pits and booby traps used against the Americans and United Nations forces. Pretty crazy stuff!Towards the end, we walked through galleries on more recent conflicts involving China like the Sino-Indian War in 1962 and China's border clashes with Vietnam in the 1970s-1980s. There were lots of artifacts like captured Indian and Vietnamese equipment and weapons.The final exhibition introduced China's modern military capabilities with aircraft, tanks, missiles and warships. Walking past modern Chinese tanks, jets, and naval ships gave me an immense sense of national pride. China has certainly come a long way from its humble revolutionary beginnings!Overall, the Chinese People's Revolutionary Military Museum was an amazing experience that really brought history to life. Itreminded me of the great sacrifices made to establish the New China we live in today. While some parts were sad, I felt inspired by the resilience and fighting spirit of the Chinese people over the decades.I'm already bugging my parents to take me back so I can see the exhibits again. Maybe next time my brother will find it cooler too. In any case, I'd highly recommend this museum to anyone interested in China's military history and accomplishments defending our great nation. Just be prepared for an extremely educational and eye-opening experience!篇6Certainly! Here's an essay about the Chinese People's Revolution Military Museum, written in English from the perspective of an elementary school student, with a length of approximately 2,000 words.Title: My Visit to the Chinese People's Revolution Military MuseumLast summer, my parents took me on an exciting trip to the Chinese People's Revolution Military Museum in Beijing. I had heard about this museum before, but I never imagined howfascinating and educational it would be until I experienced it myself.As we approached the museum, I was immediately struck by its impressive size and grand architecture. It looked like a fortress from the outside, with tall walls and imposing gates. I couldn't wait to see what was inside!Once we entered, we were greeted by a massive courtyard with tanks, cannons, and other military vehicles on display. My eyes widened with amazement as I gazed upon these mighty machines. I had never seen anything like them up close before!Our first stop was the main exhibition hall, which covered the history of the Chinese People's Revolution from the early 20th century to the end of the Chinese Civil War in 1949. The hall was filled with all sorts of interesting artifacts, including weapons, uniforms, photographs, and personal belongings of soldiers.One of the highlights for me was the life-size diorama depicting the famous Battle of Huai-Hai in 1948. It showed thousands of tiny soldiers engaged in combat, with tanks and artillery firing in all directions. The level of detail was incredible, and it gave me a sense of what those intense battles must have been like.Another exhibit that caught my attention was the one dedicated to the Long March, which was a massive military retreat undertaken by the Red Army in the 1930s. There were maps, photographs, and even a replica of the makeshift boats used to cross the treacherous Dadu River. I couldn't imagine how difficult and dangerous that journey must have been!As we moved through the museum, we learned about the various military strategies and tactics employed by the Red Army, as well as the sacrifices made by countless soldiers and civilians during the revolution. It was a sobering reminder of the hardships and struggles that our nation has endured to achieve its freedom and independence.One of my favorite sections was the outdoor exhibition area, where we got to see actual tanks, planes, and other military vehicles up close. I was amazed by their size and power! I even had the chance to climb inside a tank and imagine what it must have been like for the soldiers who operated these machines.But the museum wasn't just about weapons and battles. There were also exhibits highlighting the role of women in the revolution, as well as the contributions of various ethnic minorities. It was fascinating to learn about the diverse groups of people who came together to fight for a common cause.As we neared the end of our visit, we came across a section dedicated to the modern Chinese military. There were displays of cutting-edge technology, including drones, missiles, and advanced communication systems. It was a stark contrast to the older exhibits, but it also showed how far China's military capabilities have come over the years.Overall, my visit to the Chinese People's Revolution Military Museum was an unforgettable experience. I learned so much about our nation's history and the brave men and women who fought for our freedom. It was a humbling and eye-opening experience that gave me a newfound appreciation for the sacrifices made by those who came before us.I would highly recommend this museum to anyone interested in history, especially the history of China's military and revolutionary struggles. It's an incredible place that brings the past to life in a way that books and classrooms simply cannot. I can't wait to visit again and learn even more about our nation's rich and inspiring history.。

BUILDING_THE_BRIDGE

BUILDING_THE_BRIDGE

O n October 17 and 18, 2023, the 3rd Belt and Road Forum for International Cooperation was held in Beijing, China. H.E. Mr. Srettha Thavisin, PrimeMinister of the Kingdomof Thailand, attended and engaged in discussionswith representatives from Chinese enterprises on bilateral investment and cooperation. On social media, he posted a doodle of a map of the proposed Land Bridge project in southern Thailand and commentedon the encouraging resultsof his communication with representatives from Chinese railway enterprises.On November 3, Srettha Thavisin met Chinese Ambassador to ThailandHan Zhiqiang and stressed Thailand’s enthusiasm about cooperating with China to fund and build the Land Bridge. Srettha Thavisin pledged to authorize the Ministry of Transport and Board of Investment (BOI) to negotiate with the Chinese government on specific investment means and other cooperation details of the project.Snowballing attentionon the project has ensured the bridge becomes a major component of China-Thailand connectivity cooperation. Canal or BridgeThe Land Bridge projectis located on the Isthmus ofKra, the narrow neck of theMalay Peninsula. The isthmusseparates the Gulf of Thailandto the east from the AndamanSea to the west and is only56 kilometers wide at itsnarrowest point.The area was an importantroute for the Maritime SilkRoad as early as in the HanDynasty (206 BC-AD 220).According to the Treatiseon Geography in the Book ofHan, the official dynastichistory of the Han Dynasty,the ancient Chenli Kingdomand Fugandulu Kingdom weresituated on the eastern andwestern sides of the MalayPeninsula, respectively, andpeople had to walk for morethan ten days to travel betweenthe two locations.The geographical dividemade maritime transportationbetween the two areas quiteinconvenient because shipshad to circumnavigate thepeninsula and cross the Straitof Malacca to shuttle back andforth, which contributed to thedevelopment of Singapore.Many leaders of Thailandhave sought to connect the twosides and develop the area intoa shipping, trade, and financialhub of Southeast Asia. As earlyas in the Ayutthaya Kingdom(1351-1767), nobles attempted todig a canal across the Isthmusof Kra to connect the PacificOcean and the Indian Ocean.Before the 20th Century,British and French colonizersrepeatedly proposed to theroyal family of the Chakridynasty that they could dig acanal in the area. In the 21stCentury, canal plans havecontinued to regularly featurein the planning of the Thaigovernment.However, the canal has stillnever passed the conceptualstage despite hundreds of yearsof discussion and planning,which could be attributed tothree specific factors.First, economic factors.A canal would help cut thetravel time between the twomajor oceans by two to fivedays by eliminating 900 to1,200 kilometers, but thatadvantage would be dwarfedby the performance of majorglobal canals. For example,the Panama Canal shortensvoyages by over 8,200kilometers, and the Suez Canalreduces journeys by morethan 10,000 nautical miles.Therefore, the appeal of a canalin the Isthmus of Kra wouldbe fairly limited, and it wouldlikely take much longer for theeconomic benefits to cover themassive construction costs.Second is the environment.The canal would bring notonly many ships but alsotheir pollution, whichcould be detrimental to thelocal tourism industry andecosystem of the beautifulThe Land Bridge project will bring both opportunities and challenges to ThailandSnowballingattention onthe projecthas ensuredthe bridgebecomesa majorcomponentof China-Thailandconnectivitycooperation.62Hand-drawn illustration of the Land Bridge project by Prime Minister of Thailand Srettha Thavisin. (SOCIAL MEDIA PLATFORM)Business & Industry65outlining plans to develop the Eastern Economic Corridor (EEC) and Southern Economic Corridor (SEC), boost industrial upgrades, and enhance international competitiveness.Currently, EEC is enjoying rapid progress, with the China-Laos-Thailand railway playing a key role in aligning it with the BRI. Construction of the SEC is poised to become a focal point for the new Thai government’s endeavors, and the Land Bridge project is expected to be linked to China’s 21st Century Maritime Silk Road, which has strategic importance for both China and Thailand.The Land Bridge will advance economic and trade cooperationbetween both countries and facilitate alignment of supply and demand as well as connectivity.Thailand’s southern region is a major agricultural production area, and its agriculture contributes approximately 30 percent to the region’s GDP. The region has huge export demand for products such as rubber, seafood, wood products, and palm oil, but local demand for imports is smaller. This imbalance means that many vessels have to sail empty to local ports, which increases transportation costs.Hence, insufficient shipping capacity has pushed many products produced in southern Thailand to take a longer route. They would first be transported by land to the port of Penang in Malaysia or ports in Bangkok and Laem Chabang in eastern Thailand before being exported abroad. The problem has also dampened trade between China and Thailand despite China being the largest export market for agricultural products from southern Thailand. Laem Chabang Port and Chumphon Port, included in the Land Bridge project, are each designed to handle throughput of 20 million TEUs, making them well-positioned to address this problem effectively.The Thai government also proposed seizing the Land Bridge project as an opportunity to promote industrial upgrading and transformation in southern Thailand. The plan includesreclaiming land in the port areas and building supporting facilities as well as establishing industrial zones to attract foreign investment. The country has outlined plans to import electronic components from China, process them in the Land Bridge area, and then export the finished products to countries in Southeast Asia, the Indian Ocean, and along the Pacific coast, which would make the country a crucial link in the transoceanic supply chain.China and Thailand have previously collaborated on the construction of the Thai-Chinese Rayong Industrial Zone in eastern Thailand, which has since served as a successful model for bilateral investment and industrial cooperation. Many expect the Land Bridge to replicate this cooperation model in southern Thailand.In addition to promoting China-Thailand trade, the Land Bridge project will inject greater vitality into cooperation between China and ASEAN. China-ASEAN trade and investment has been gaining momentum since the entry intoforce of the Regional Comprehensive Economic Partnership (RCEP) in 2022. According to the plan for the Land Bridge, Chumphon Port will become the largest port on the western coast of the Gulf of Thailand, and the oil and gas pipelines included in the project are designed to alleviate the increasing burden on the Strait of Malacca. Since Thailand is situated at the geographic center of ASEAN, the Land Bridge has great potential to become a hub for shipping, trade, and energy transportation. China’s extensive participation in the project will create a new route to extend the 21st Century Maritime Silk Road. The Thai government expects big things from the Land Bridge, and Prime Minister Srettha Thavisin has expressed considerable enthusiasm for China’s participation in theproject. However, the project still faces multiple difficulties and challenges.The first problem is funding. According to data released by the Thai Cabinet, total investment in the Land Bridge project will exceed 1.012 trillion Thai Baht (US$27.72 billion), which is more than twice the total cost of the first and second phases of the Bangkok-Nong Khai section of the China-Thailand High-speed Railway. The construction period for the Land Bridge will be lengthy and will involve massive costs as well as significant investment risks. Now, the Thai government is attracting investment for the project through a Public-Private Partnership (PPP) model, which brings the challenge of coordinating the interests of various participants.The second obstacle isenvironmental consideration. The Land Bridge could have adverse effects on the marine ecosystem in Southern Thailand and potentially lead to losses for local tourism and fishery due to increased maritime traffic. Therefore, multiple rounds of environmental assessments are necessary before advancing theproject, including listening to voices from local people and gaining their trust to address the concerns of the community.Lastly, the project faces challenges from both domestic and international political environments. Domestically, the Thai government needs to address issues of uneven resource allocation across regions, and internationally, it must navigate competition with neighboring countries for maritime resources. As the American Indo-Pacific strategy proceeds, the United States and India could becomenervous about China gaining greater influence in the Gulf of Thailand and the Andaman Sea. If Thailand adheres to its traditional conservative “balanced diplomacy,” the Land Bridge project could get stuck.About the author Tian Lin is a lecturer at the School of Asian Studies at Beijing Foreign Studies University.。

《11规则》题库第二章航海仪器测试题

《11规则》题库第二章航海仪器测试题

《11规则》题库第二章航海仪器测试题基本信息：[矩阵文本题] *1. ______ is not required by bridge-to-bridge communications. [单选题] *VHFSARTNAVTEXLES(正确答案)2. As for Racon, which one is incorrect in the following? [单选题] *Racon is a radar transponderRacon is often installed on major waypointsWhen activated by a radar signal, the Racon sends it back with an identifier Racon can be used to take place of radar(正确答案)3. PAN-PAN repeated three times over the radiotelephone indicates which type of message will follow? [单选题] *DistressSafetyAll clearUrgency(正确答案)4. Automatic identification systems (AIS) are expected to broadcast all of the following information except ______. [单选题] *port of origin(正确答案)name of vesselcourse and speed over grounddraft of vessel5. What does a navigator who uses an ECDIS require? [单选题] *Good navigational knowledge and a professional job attitude(正确答案)Good computer knowledgeGood system knowledgeNothing special6. The terrestrial system of GMDSS consists of ____________. [单选题] *radio-telephony, DSC, Direct Printing Telegraphy, Navtex and SART(正确答案) INMARSAT, DSC, Direct Printing Telegraphy, Navtex and SARTradio-telephony, DSC, EPIRB, Navtex and SARTStatus Recording system, DSC, Direct Printing Telegraphy, Navtex and SART7. The ______ provides the link between the Space Segment and the land-based National/International fixed communications networks. [单选题] *VHFSARTNAVTEXLES(正确答案)8. If the electronic chart is part of an ECDIS, it must display the minimum data required by IMO/IHO, to include all the following EXCEPT ______. [单选题] *hydrographyaids to navigationtidal current(正确答案)regulatory boundaries9. When a call is complete，and subsequently during an exchange of messages，a station invites a reply by saying ___. [单选题] *“Over”(正确答案)“Out”“OK”“Roger”10. What is the correct speed input to an ARPA used for traffic surveillance? [单选题] *Ground speedSpeed through water(正确答案)Speed from GPSSpeed from Doppler11. All echo-sounders can measure the ______. [单选题] *actual depth of wateractual depth of water below keel(正确答案)average depth from waterline to hard bottomaverage depth of water to soft bottom12. A satellite navigation system with global coverage may be termed as global navigation satellite system or _____. [单选题] *GNSS(正确答案)EPIRBSSASECDIS13. The VDR system is designed to operate_____ once it is set up correctly. There is no user interaction . [单选题] *automatically(正确答案)accuratelypromptlyConspicuously14. What is the MOST important thing you should do before transmitting on a marine radio? [单选题] *Ask for permissionRecord the time in your radio logPress the push to talk button three timeMonitor the channel to ensure that it is clear(正确答案)15. While underway, a vessel over 100,000 gross tons with an automatic identification system (AIS) is expected to broadcast all of the following information every 1 to 10 seconds EXCEPT ______. [单选题] *rate of turnname of the vessel(正确答案)navigational statusship’s heading16. The GPS system was designed for ______ satellites. [单选题] *3121824(正确答案)17. What is important to check when transferring a position from GPS to a chart? [单选题] *Reading the position correctlyPlotting the position correctlyMake sure that the chart and the GPS use same datum(正确答案)Make sure the map is updated18. You are using a radar in which your own ship is shown at the center, and the heading flash always points to 0 degree, If bearings are measured in relation to the flash, what type of bearings are produced? ______. [单选题] *Relative(正确答案)TrueCompassMagnetic19. The compass error of a magnetic compass that has no deviation is ______. [单选题] *zeroequal to variation(正确答案)eliminated by adjusting the compassconstant at any geographical location20. A radar range to a small，charted object such as a light will provide a line of position in the form of ______. [单选题] *straight linearc(正确答案)parabolahyperbola21. You have another ship overtaking you close aboard to starboard. You have 3 radar targets bearing 090，0.5 mile, 1 mile，and 1.5 miles. In this case，the unwanted echoes are called ______. [单选题] *Multiple echoes(正确答案)SpokingIndirect echoesSide-lobe echoes22. What is the main purpose of DGPS? [单选题] *Improve positioning accuracy(正确答案)Decrease positioning accuracyReduce operational costI don't know23. When it is accepted to remain on the frequency indicated，you should say ______. [单选题] *standing by on VHF frequency(正确答案)coming to VHF frequencyVHF frequency is the best place for you to stay byremaining in frequency and do not change24. The satellite systems of GMDSS comprise ______. [单选题] *NAVTEX, COSPAS/SARSAT, EPIRBs and Status Recording-systemInmarsat, COSPAS/SARSAT, EPIRBs and Status Recording-system(正确答案) NAVTEX, Inmarsat, EPIRBs and SARTInmarsat, Direct Printing Telegraphy, and DSC25. When another calling channel/frequency is available，do not use ______ or other safety frequencies to make a transmission. [单选题] *2182 kHz or VHF Channel 16(正确答案)VHF Channel 76FAXCABLES26. How to reduce beam width distortion? [单选题] *Adjust centre positionAdjust brillianceAdjust heading markerReduce gain(正确答案)27. ______ is on the panel of DF. [单选题] *ZERO CLEARING(正确答案)ANTI-CLUTTER-RAINDIMMERCURSOR28. In radiotelephony，the spoken word for distress is ______. [单选题] *SecuriteSafetyEmergencyMAYDAY(正确答案)29. Which one of the followings is incorrect about magnetic compass? [单选题] *The magnetic compass is compulsory on my vesselThe magnetic compass is prone to errorThe magnetic compass is always placed inside steel constructions(正确答案)The magnetic compass needs to be calibrated to compensate for local magnetic distortion 30. Radar reflectors are required for ______. [单选题] *all fishing vessels over 39 feet in lengthsail-propelled fishing vesselsall fishing vessels of less than 200 GTwooden hull fishing vessels with a poor radar echo(正确答案)31. If there were suddenly an immediate danger for both the vessel and its crew, would you send a MAYDAY on__ [单选题] *Ch06 with dual watchCh06 with 25 watts outputCh16 with 1 watt outputCh16 with 25 watts output(正确答案)32. The line connecting the Loran-C master station with a secondary station is called the ______. [单选题] *focus linebase line(正确答案)side linecenter line33. If a GMDSS radio operator initiates a DSC distress transmission but does not insert a message，what happens? [单选题] *The transmission is aborted and an alarm sounds to indicate this data must be provided by the operatorThe transmission is not initiated and “ERROR” is indicated on the display readoutThe transmission will be made with “default” information provided automatically(正确答案)The receiving station will poll the DSC unit of the vessel in distress to download the necessary information34. Ship to ship communications during SAR should be executed by _____. [单选题] * VHFMFSatelliteVHF and MF(正确答案)35. The indicated heading should not be relied on ________. [单选题] *until the gyrocompass has settled(正确答案)until the “Ready” lamp will be litwhen the alarm is generatedwhen the red “Power” lamp RCU illuminates36. When your vessel is proceeding to the area of traffic density，______ is used to determine the exact ranges of other ships or objects in the vicinity. [单选题] * Radar(正确答案)GPSDFSatellite Navigator37. Magnetic heading differs from compass heading by _______. [单选题] * compass errortrue headingvariationdeviation(正确答案)38. What is the primary equipment for receiving MSI ________. [单选题] *SARTEPIRBNAVTEX(正确答案)INMARSAT-B39. If the gyrocompass error is east，what describes the error and the correction to be made to gyrocompass headings to obtain true headings ________. [单选题] *The readings are too low（small numerically）and the amount of the error must be added to the compass to obtain true(正确答案)The readings are too low and the amount of the error must be subtracted from the compass to obtain trueThe readings are too high（large numerically）and the amount of the error must be added to the compass to obtain trueThe readings are too high and the amount of the error must be subtracted from the compass to obtain true40. If the magnetic heading is greater than the compass heading，the deviation is ______. [单选题] *east(正确答案)westnorthsouth41. Deviation which is maximum on intercardinal compass headings may be removed by the ______. [单选题] *Flinders barTransverse magnetsFore-and-aft magnetsSoft iron spheres on the sides of the compass(正确答案)42. The accuracy of the DGPS mainly depends on_______. [单选题] *the price of the equipmentthe relative angle between the satellitethe position of the observerthe age of the calculated correction(正确答案)43. Which statement concerning locating signals in the GMDSS is FALSE? [单选题] *Locating signals are transmitted by survival craft VHF transceivers.(正确答案) Locating signals are transmitted by SARTS.Locating signals are intended to facilitate the finding of a distressed vessel or its survivorsLocating signals are not transmitted by auto alarm generators.44. Coral atolls, or a chain of islands at right angles to the radar beam, may show as a long line rather as an individual targets due to ______. [单选题] *the effects of beam width(正确答案)limitations on range resolutionthe pulse length of the radarthe multiple-target resolution factor45. Quadrantal error in a gyrocompass has its greatest effect ______. [单选题] *in high latitudesnear the equatoron north or south headingson intercardinal headings(正确答案)46. What is important to remember when using AIS for collision avoidance? [单选题] *AIS may not give a complete picture of the traffic situation(正确答案)AIS is more accurate than ARPAAIS is not as accurate as ARPAAIS is not allowed to be used for collision avoidance47. Integrated Bridge and Navigation Systems (IBS/INS) provide excellent performance and reliable navigation under all conditions by _____. [单选题] *integrating well-proven, harmonizing equipment(正确答案)integrating all equipment in the bridgean intelligent platform with ECDIS and Radarthe control center based on ECDIS48. Which statement concerning GPS is TRUE ________. [单选题] *It cannot be used in all parts of the worldThere are 12 functioning GPS satellites at presentIt may be suspended without warning(正确答案)Two position lines are used to give a 2D fix49. When hitting a solid object such as a ship or an airplane, the radar waves are reflected back ______ they came. [单选题] *in the waythe wayby the waythrough the path(正确答案)50. A Doppler log in the volume reverberation mode indicates ______. [单选题] *speed being made goodspeed through the water(正确答案)the set of the currentthe depth of the water51. ECDIS must be able to perform all of the following EXCEPT ______. [单选题] *determine true bearing and distance between two geographical pointsdetermine magnetic compass deviation(正确答案)transform a local datum to the WGS-84 datumconvert “graphical coordinates” to “display coordinates”52. According to SOLAS the breathing air apparatus that must be onboard shall have sufficient capacity for how many minutes of operation? [单选题] *2030(正确答案)456053. Which factor has the greatest effect on the amount of gain required to obtain a fathometer reading? [单选题] *Salinity of waterTemperature of water(正确答案)Atmosphere pressureType of bottom54. Your ARPA has two guard zones. What is the purpose of the inner guard zone? [单选题] *Alert the watch officer that a vessel is approaching the preset CPA limitWarn of small targets that are initially detected closer than the outer guard zone(正确答案)Guard against target loss during critical maneuvering situationsSound an alarm for targets first detected within the zone55. ETA／PILOT REVERTING means [单选题] *ETA pilot station has been givenETA pilot station will be given afterwards(正确答案)ETA pilot station was not givenETA pilot station is given56. ________is used for providing homing signals from survival craft for detection by 9 GHz radar. [单选题] *NAVETEX receiverSearch and Rescue Transponder(正确答案)Emergency Position Indicating Radio BeaconDigital selective calling57. ______ is used for safety of navigation ship-to-ship. [单选题] *Channel 6Channel 13(正确答案)Channel 16Channel 7058. Which action should you take after sending a false distress alert on VHF? [单选题] *Send a DSC cancellation message on Ch-70.Make a voice announcement to cancel the alert on Ch-16.(正确答案)Make a voice announcement to cancel the alert on Ch-13.Make a voice announcement to cancel the alert on Ch-22A.59. ______ typically extends from close as 0.1 nautical miles out to 32 NM. [单选题] *EBLVRMCRTtarget tracking range(正确答案)60. When own ship’s position input to ECDIS is wrong, what is the result? [单选题] *NothingECDIS will give warningECDIS will automatically be switched offPosition, range and bearing taken on the ECDIS will be wrong(正确答案)61. The radar control used to reduce sea return at close ranges is the ______. [单选题] *Gain controlSensitivity time control(正确答案)Fast time constantPulse length control62. The common way to obtain your ship’s position is ______. [单选题] *keeping a close watch and lookouttaking a radar range and bearing(正确答案)observing a radar target and listening to signalskeeping a well clear caution63. A radar display in which North is always at the top of the screen is a（n）______. [单选题] *Unstabilized displayStabilized display(正确答案)Composition displayRelative display64. ______ is a radio receiver with ability to sense direction of the incoming radio waves. [单选题] *The echo sounderThe radarThe course recorderThe direction finder(正确答案)65. The abbreviation RYC in a marine cable generally stands for ______. [单选题] *referring to your crewreference for your captainreturn to your cabinreceived your cable(正确答案)66. How long must the GMDSS radio log be retained on board ________. [单选题] *At least two years after the last entry(正确答案)At least one year after the last entryAt least 90 days after the last entryAt least 30 days after the last entry67. The angular difference between the true meridian（great circle connecting the geographic poles）and the magnetic meridian（direction of the lines of magnetic flux）is called ______. [单选题] *deviationvariation(正确答案)errordifference68. If you receive the signal over radiotelephone of Romeo Papa Tango while using the International Code of Signals, you should ______. [单选题] *report to the callerrepeat your last transmission(正确答案)continue since he received your last transmissionend the transmission69. Deviation changes with a change in ______. [单选题] *latitudeheading(正确答案)longitudesea conditions70. How does current and drift effect the relative motion, relative vector presentation? [单选题] *No effect(正确答案)Producing small errors in calculated aspectProducing large errors in calculated aspectProduce errors in calculated CAP/TCPA71. A single vertical magnet placed underneath the compass in the binnacle is used to compensate for ______. [单选题] *the horizontal component of the permanent magnetismdeviation caused by the vessel's inclination from the vertical(正确答案)induced magnetism in the horizontal soft ironinduced magnetism in the vertical soft iron72. The receiver uses ______ satellites to compute latitude，longitude，altitude，and velocity. [单选题] *onetwothreefour(正确答案)73. ______ is used for calling and replying, and for transmitting acknowledging and relaying distress alerts. [单选题] *NAVTEX receiverSearch and Rescue TransponderEmergency Position Indicating Radio BeaconDigital selective calling(正确答案)74. How is an uncoded racon displayed on the PPI? [单选题] *As a line(正确答案)As a dotAs a small circleAs a large circle75. Variation is a compass error that you ______. [单选题] *can correct by adjusting the compass cardcan correct by adjusting the compensation magnetscan correct by changing the vessel’s headingcannot correct(正确答案)76. Before sailing, mariners on duty shall check the headings of magnetic compass by comparison with _____. [单选题] *ship’s clockengine movement recorderrepeaters(正确答案)navigation lights77. ____ is the navigational timekeeper of the vessel. [单选题] *The marine sextantThe chronometer(正确答案)The magnetic compassThe gyrocompass78. A(n) ______ indicates that there is serious and immediate danger for vessel, crew and passengers. [单选题] *distress alert(正确答案)urgency messagesafety messageroutine message79. Which one of the followings is a standard phrase? [单选题] *WARNING. You are running into danger.(正确答案)You are possibly running into danger.You could be in the case of running into danger.You could , I think , be running into danger.80. What is the right way to use VHF CH16 and working channel? [单选题] *Ships can call other ships on Ch16 but should move to a working channel as soon as possible.(正确答案)Ship should use working channel to call other ships at any time.Ch16 is only used as the international distress and calling frequency.Ship can use Ch16 or working channel as they like81. The ship LRIT system shall transmit the ship’s LRIT information at ______ to an LRIT DATA center ? [单选题] *1-hour interval2-hour interval3-hour interval6-hour intervals(正确答案)82. In ________ within coverage of an Inmarsat geostationary satellite, continuous alerting is available. [单选题] *Sea Area A1Sea Area A2Sea Area A3(正确答案)Sea Area A483. How to report your ship call sign to a shore station? [单选题] *Use capital lettersUse phonetic alphabet(正确答案)Use letters and numbersUse flag signals84. Any piece of metal on becoming magnetized will develop regions of concentrated magnetism called ______. [单选题] *fluxpoles(正确答案)magnetsazimuth85. ____ is used for measuring horizontal and vertical angles. [单选题] *The marine sextant(正确答案)The chronometerThe magnetic compassThe gyrocompass86. Which of the following is defined as static information? [单选题] *Navigational statusSafety related messageMMSI(正确答案)Route plan87. The ______ transmits own ship data cyclically via two defined VHF channels and receives the same data of the other ships and objects that are equipped with AIS systems. [单选题] *AIS(正确答案)ECDISGPSVDR88. What are the only magnetic compass correctors that correct for both permanent and induced effects of magnetism？ [单选题] *Quadrantal spheresHeeling magnets(正确答案)Athwartships magnetsFore-and-aft magnets89. All VHF marine band radios operate in the simplex mode, which means that ______. [单选题] *only one person may talk at a time(正确答案)only two persons may talk at the same timethe radio only transmitsthe radio only receives90. What type of radar can activate a racon? [单选题] *X-band radar(正确答案)S-band radarC-band radarNo radar can91. Your radar is set on a true motion display. Which of the following will NOT appear to move across the PPI scope? [单选题] *Echoes from a buoy(正确答案)Own ship's markerEcho from a ship on the same course at the same speedEcho from a ship on a reciprocal course at the same speed92. What is the spoken emergency signal for a “man overboard” on the VHF radio? [单选题] *Man OverboardSecurityMaydayPan-Pan(正确答案)93. When the transmissions of a radio station have broken down, switched off or suspended, it is _______. [单选题] *unfunctionalbreak downoff poweroff air(正确答案)94. The maritime radio system consisting of a series of coast stations transmitting coastal warning is called______. [单选题] *NAVTEX(正确答案)HYDROLANT/HYDROPACNAVAREASAFESEA95. If a magnetic compass is not affected by any magnetic field other than the Earth's，which statement is TRUE? [单选题] *Compass error and variation are equal(正确答案)Compass north will be true northVariation will equal deviationThere will be no compass error96. Which device provides the main means in the GMDSS for locating ships in distress or their survival craft? [单选题] *Radio direction finderSatellite EPIRBs(正确答案)MF/HF DSCVHF homing device97. The description of RACON beside an illustration on a chart would near a ______. [单选题] *radar conspicuous beaconcircular radiobeaconradar transponder beacon(正确答案)radar calibration beacon98. A navigator fixing a vessel’s position by radar______. [单选题] *should never use radar bearingsshould only use radar bearings when the range exceeds the distance to the horizoncan use radar information from one object to fix the position(正确答案)must use information from targets forward of the beam99. Lines on a chart which connect points of equal magnetic variation are called ______. [单选题] *Magnetic latitudesMagnetic declinationsDipIsogonic lines(正确答案)100. AMVER is a system which provides ______. [单选题] *satellite communicationsnavigational informationweather informationposition reporting service(正确答案)。

综合英语第三册Unit9课件

综合英语第三册Unit9课件


Practice answers
Answer to question 2
Correct answer: C
Explanation: The correct answer is C because the text mentions that the company has a strong commitment to customer service.
The important words and phrases are identified, and their meanings are explained. The context in which these words are used is also considered to understand their precise meaning and significance in the text.
Comprehensive English Volume 3 Unit9 Courseware
目录
• Introduction to the background of the text
• Analysis of Text Content • Analysis of language points in
such as justice, morality, and human nature.
02
Plot
The plot revolves around a series of mysterious murders in a
small town, with a famous detective trying to solve the case.
Author's name: John Smith