09-two rail sweep and weaves

合集下载

Trans-Siberianrailway

Trans-Siberian railwayIn 19 century i n Russia the grandi ose ci v il-engineering design of rail way s - Trans-Siberian railway was c arried out. The new railway had s urpass ed by it's technical design all other railway s of the world. T he Trans-Siberian rail way, by the right, was named The Great Si berian railway, has being attrac k ed the attenti on of the public all over the world more than c entur y. The Trans-Si berian railway connects Europe and Asia, crossing thr ough the l argest cities of Russi a. Trav eling along the Trans-Siberian railway. You will get the fullest i magine about the c ountr y, all the tours include v isit the greatest Lak e Bai k al. It is one of the biggest and most ancient lakes of the world and famous by i t's unique nature and s ev er e beauty.St.-Petersburg - Moscow - Irkutsk - the Lake Baikal(12 days\11 nights)ItineraryDay 1. Arriv e i n St.Petersburg. Transfer to the hotel. Accommodation in hotel “Pribaltiy s kay a” 4* (a s pectacular l ocati on on the Gulf of Fi nland).Day 2. F ull city tour by bus (incl udes v isits to Pal ace Square, the Neva embankment, the Pis k ar yov s k oe Memorial Cemeter y). Lunch. Visit to the H ermitage M useum and Winter Palac e (optional).Day 3. One-day trip to Peterhof (Petrodvorets) - the i mperial s ummer residence on the Gulf of Finland. It is famous by the Big Palac e and par k s with unique fountai ns. Dinner. Transfer to the rail way s tati on. D eparture by train to Moscow.Day 4. Arriv e i n Moscow. City tour by bus (incl uding v isits to the Red Square, the Gum D epartment Store, the Bolshoi Theater, Manezh Square, Moscow State Uni versity on the Voroby ovy Hills overlook ing the city) Lunc h. Accommodation in the hotel “Rossiya” (location near the Red Square on the bank of the Mos kva River). Ex cursion to the Kremlin with Cathedral and the Armory Chamber (the unique c ollection of the Russian ts ar's treasuries).Day 5. Ex cursion to "Kolomens k oye" - the former summer residence of R ussian tsars (optional). Lunc h. Ex cursion to State Trety ako v Art Galler y - the c ollection of world famous pai ntings of Russian and Sov iet artists, as well as scul ptures and graphic art.Dinner. Trans fer to the rail way s tati on. D eparture by trai n № 10 "Bai kal" to Irkuts k.Day 6 - 8. En route.Day 9. Arriv e i n Ir k uts k. Trans fer to the Lak e Bai kal (Listvy ank a). Accommodation in the hotel “Bai k al”. Sights eeing ex c ursion with v isit St.Nicolas Orthodox C hurch, local farm mar k et, souv enirs shop. Ex cursion to the museum of flora and fauna of the Lake Bai k lal. Afternoon - boat trip along the s horeline of the Lake Baikal. Dinner.Day 10. Departure from Listvyanka. En route - museum of wooden architec ture "T altsi". Arrive to Ir k uts k. Acc ommodati on i n hotel “Bai k al Business Center”. City tour with v isits Znamens ky Monaster y with the famous ic onostasis, the Angara embankment, and buildings, created in Siberian baroque. Dinner.Day 11. Ex cursion to the c enter of the Buryat autonomous region Ust-Orda. Visit the historical museum with folk program and meeting with s haman. Dinner (national Buryatk itchen). D eparture to Ir kuts k. Shoppi ng. Dinner.Day 12. Transfer to airport. Departure from Ir k uts k.Total length of journey: 12 day s\11 nights.Includes: all accommodati ons i n the hotels based on double occupanc y, 3 meals per da y, sights eeing pr ogram, all entranc e fees and taxes, guide s erv ices, all transfers, railway tic kets: St.Petersburg - Moscow 2nd cl ass (4- berth c abi n) and Mosc ow-Ir k uts k 2nd cl ass (4-berth c abin).Non-included: international and i nternal airfar es, passport and v isa fees, medical and trip i nsurance, optional ex c ursions.Moscow - Irkutsk - the Lake Baikal - Ulan-Bator(13 days\12 nights)Day 1. Arriv e i n Moscow. Accommodati on in the hotel “Rossiya” (locati on near the Red Square on the bank of the Mos kva Ri v er). Dinner.Day 2. City tour by bus (including v isits to the Red Squar e, the Gum Department Store, the Bolshoi T heater, Manez h Square, Mosc ow St ate Uni v ersity on the Vor oby ovy Hills overlook ing the city). Lunch. Ex c ursion to the Kremlin with C athedral and the Armor y Chamber (unique c ollection of the Russi an ts ar's treas uries).Day 3. Ex cursion to "Kolomens k oye" - the former summer residence of R ussian tsars (optional). Lunc h. Ex cursion to State Trety akov Art Galler y - the c ollection of world famous pai ntings of Russian and Sov iet artists, as well as scul ptures and graphic art. Dinner. Transfer to the railway station. Depar tur e by train № 10 "Bai k al" to Ir k uts k.Day 4 - 6. En routeDay 7. Arriv e i n Ir k uts k. Trans fer to the Lak e Bai kal (Listvy ank a). Accommodation in the hotel “Bai k al”. Sights eeing ex c ursion with v isit St.Nicolas Orthodox C hurch, local farm mar k et, souv enirs shop. Ex cursion to the museum of flora and fauna of the Lake Bai k lal. Afternoon - boat trip along the s horeline of the Lake Baikal. Dinner.Day 8. Departure from Listvy ank a. En route - mus eum of wooden arc hitecture "Taltsi". Arriv e to Irkuts k. Accommodation in hotel hotel “Bai k al Business Center”. City tour with v isits Znamens ky Monaster y with the famous ic onostasis, the Angara e mbankment, buildings, created in Si berian baroque. Dinner.Day 9.Ex c ursion to the c enter of the Bur y at autonomous region Ust-Orda. Visit the historical museum with folk program and meeting with s haman. Dinner (national Bur y atk itchen). D eparture to Ir kuts k. Shoppi ng. Dinner. Departure to Ulan-Bator by train.Day 10. En route.Day 11. Arrive in Ulaan -Baator. Acc ommodation in "Chinggis Khaan" hotel. City tour includi ng a v isit to Gandan Buddhist monastery. Visit to winter Pal ace of Bodh Khaan. Day 12. Tour to "Mirage" ger-camp. Ex c ursion to T urtle roc k. Lunch at the camp. Horsebac k riding tour. Visit to nomadic famil y. Stay ov er night at the camp.Day 13. Driv e bac k to the city. Visit to "Chinggissin Huree" camp. Visit to Gr eat C hinggis Khaan mus eum. Dri v e bac k to the city. Ex c ursion to N atural History Museum with a display of di nos aurs remains. Departure to airport.Total length of journey: 13 day s\12 nights.Includes: all accommodati ons i n the hotels based on double occupanc y, 3 meals per day, sights eeing pr ogram, all entranc e fees and taxes, guide s erv ices, all transfers, railway tic kets: Mosc ow-Irkuts k 2nd class (4-berth c abin) and Ir k uts k - Ulan-Bator 2nd class (4-berth c abi n).Non-included: international and i nternal airfar es, passport and v isa f ees, medical and trip i nsurance, optional ex c ursions.Moscow - Irkutsk - the Lake Baikal - Vladivostok(13 days\12 nights)Day 1. Arriv e i n Moscow. Accommodati on in the hotel “Rossiya” (location near the Red Square on the bank of the Mos kv a River). Dinner.Day 2. City tour by bus (including v isits to the Red Squar e, the Gum Department Store, the Bolshoi T heater, Manez h Square, Mosc ow St ate Uni v ersity on the Vor oby ovy Hills overlook ing the city). Lunch. Ex c ursion to the Kremlin with C athedral and th e Armor y Chamber (unique c ollection of the Russi an ts ar's treas uries).Day 3. Ex cursion to "Kolomens k oye" - the former summer residence of R ussian tsars (optional). Lunc h. Ex cursion to State Trety akov Art Galler y - the c ollection of world famous pai ntings of Russian and Sov iet artists, as well as scul ptures and graphic art. Dinner. Transfer to the railway station. Departur e by train № 10 "Bai k al" to Ir k uts k.Day 4 - 6. En routeDay 7. Arriv e i n Ir k uts k. Trans fer to the Lak e Bai kal (Listvy ank a). Accommodation in the hotel “Bai k al” . Sights eeing ex cursion with v isit St.Nicolas Orthodox Church, local farm mar k et, souv enirs shop. Ex cursion to the museum of flora and fauna of the Lake Bai k lal. Afternoon - boat trip along the s horeline of the Lake Baikal. Dinner.Day 8. Departure from Listvy ank a. En route - mus eum of wooden arc hitecture "Taltsi". Arriv e to Irkuts k. Accommodation in hotel “Bai kal Busi ness C enter” . City tour with v isits Znamens ky Monaster y with the famous ic onostasis, the Angara embankment, buildings, created in Si berian baroque. Dinner. D eparture to Vladi v os tok by trai n №2.Day 9 - 11. En routeDay 12. Arrival in Vl adi v os tok. Accommodation in the hotel "Gav an". City tour. Lunch. Ex cursion to Oc eanarium. Gala-dinner in r estaurant.Day 13. Chec k out. Transfer to airport.Total length of journey: 13 day s\12 nights.Includes: all accommodati ons i n the hotels based on double occupanc y, 3 meals per day, sights eeing pr ogram, all entranc e fees and taxes, guide s erv ices, all transfers, railway tic kets: Mosc ow-Irkuts k 2nd class (4-berth c abin) and Ir k uts k - Vladivostok 2nd cl ass (4-berth c abin).Non-included: international and i nternal airfar es, passport and v isa fees, medical and trip i nsurance, optional ex c ursions.All prices are p er p erson in euro:。

轨道交通专业术语中英文对照

轨道专业术语中英文对照表Centrifugal acceleration 离心加速度Centripetal acceleration 向心加速度tilting train 摆式列车singularity/singular point 奇点rail web 轨腰guard check gauge 查照间隙grip holding resistance 防滑阻力The minimum resistance to rail longitudinal slip in the fastening system 扣件系统的最小纵向防滑阻力Resistance to repeated loading 重复负荷阻力rail ends unevenness in line or surface 错牙接头Nominal track gauge 公称轨距Spring washer 弹簧垫圈Throw of switch 尖轨动程Coolant 冷冻剂冷却液High Ductility Welded Bainitic Steel Crossings 高强韧性贝氏体钢焊接辙叉Wrench 扳手Caliper 卡尺Theoretical lead distance of the turnout 道岔理论导程Acorn nut 盖形螺母Cotter pin 开口销Measurement for payment for turnouts, crossover, scissor crossover and diamond crossings will be made of the number of complete turnouts and diamond crossings supplied to the client’s depot and accepted by the client。

道岔、渡线、交叉渡线和菱形渡线支付款的计量应由向业主车辆段提供的并经业主验收的完整道岔和菱形渡线的数量组成。

译林版英语选修9教师用书Unit2SectionⅠReading(WeletotheunitRead

你知道著名的庞贝古城吗？Historical Background of The Ancient City of PompeiiIn the early afternoon hours of August 24，79 A．D.the summit ofMount Vesuvius exploded without warning.A black river of ash andlapilli ran from the crater of the volcano down through the city of Pompeii leaving death and destruction in its wake.The magnificent ancient city of Pompeii was left buried under about 20 feet of earth and ash.Pompeii was originally only 500 meters from the sea，but after the eruption the distance to the sea increased to two kilometers.Oscans settled along the shore of the Tyrrhenian Sea on an elevated lavic spur that was created by an ancient eruption of Vesuvius during the 8th century B．C.The strategic location made Pompeii an object of great importance to the Estuscans.The Samnites arrived from the mountains of Irpinia in the 5th century，putting an end to the control of Campania by the Greeks and Etruscans.It was inevitable that Pompeii would fall under the domination of Rome at the beginning of the Samnite Wars.Pompeii became a Roman colony in 80 B．C.，taking the name “Colonia Veneria Cornelia Pompeii”which refers to both her conqueror and to the goddess Venus.Seventeen hundred years later，architect Domenico Fontana happened across some inscriptions while building a tunnel in the area.Some excavation was done near the amphitheater at that time，but no one suspected that an entire city was buried there.The first scientific exploration of the site took place in 1748，directed by Charles of Bourbon.In 1860 Giuseppe Fiorelli invented a system of pouring liquid plaster into the spaces left in the ash bed.Victims had remained in the House of the Fugitives during the volcanic eruption and the fall of ter they had tried to escape under the ashes，but suffocated.The oldest buildings of Pompeii date back to the 6th century B．C.and likely only occupied a small part of the south-western area，between the main Forum and the Triangular Forum.Pompeii gradually expanded toward the east and the north.Most of the ruins date back to its establishment as a Roman colony in 80 B．C.1．What buried the Ancient City of Pompeii in the early afternoon hours of August 24，79 A．D.?_________________________________________________________________ _________________________________________________________________ 2．Who found the Ancient City of Pompeii?_________________________________________________________________ _________________________________________________________________ 【答案】 1.A black river of ash and lapilli from the crater of the volcano.2．The architect Domenico Fontana.Ⅰ.词义搭配1．associate A．an opinion or a judgement about sb./sth. that hasbeen thought about very carefully2．theft B．to make a connection between people or thingsin your mind3．friction C．to choose sb. for a job or position of responsibility4．appoint D．disagreement or a lack of friendship amongpeople who have different opinions about sth.5．steady E．developing，growing，etc. gradually and in aneven and regular way6．assessment F．the crime of stealing sth.from a person or place【答案】 1.B 2.F 3.D 4.C 5.E 6.AⅡ.用下列短语的适当形式填空2．We built a monument on the top of the hill ______ the dead soldiers in the battle.3．He had to ________ his dream because of his bad health.4．I love playing basketball ________．5．We usually ______ lung cancer ______ smoking.【答案】 1.have an influence on 2.in honour of 3.give up 4.in particular 5.associate；withⅠ.阅读P18内容，从三个选项中选择最佳答案－191．Which of the statements is true according to the passage?A.The ancient Greeks had a greater effect on Western civilization than others.B.The marathon was created in honour of Marathon.C.The Greek civilization lasted only 2，500 years.2．How many main temples to Athena on top of the Acropolis?A.Two.B．Four.C．Three.3．What is not the factor that led to the damage to the Acropolis?A.The earthquake.B.The human being.C.The marble.【答案】1－3ACC内容，完成下列表格Ⅱ.阅读P18－196.Destroyed7.stolen8.RestorationcationalⅢ.阅读P18内容，完成下面课文缩写－19The ancient Greeks have had a 1.________ (great) influence on Westerncivilizations than others. They made many advances in various fields that 2.________ (influence) the world so far.3．________ particular, we often associate ancient Greek civilization 4.________ the capital city of Athens, the greatest symbol of which is the Acropolis.5.________ was constructed in the 5th century BC in honour of Athena，6.________ there are three main temples to Athena.But the Acropolis has been damaged partly by natural forces like earthquakes and partly by man. In 1458, the Turks 7.________(seize) control of Athens and used the Parthenon as a warehouse. In 1687, the large part of the building was destroyed 8.________ an attack from Italy caused the gunpowder to explode. In 1801, many of the best sculptures were stolen.In a gesture to help preserve history, the Greek government appointed a mittee to undertake 9.________ task. The mittee is continuing its work and hopes to bring the Acropolis back to its 10.________ (form) glory.【答案】 1.greater 2.have influenced 3.In 4.with 5.It 6.where7.seized 8.because9.the10.former。

Rail-to-Rail

Brief PapersA Rail-to-Rail Constant-(1)while the pMOS pair is in conduction for low input common-mode voltages,we can obtain a constant transconductance;for low-input common-mode voltages only the pMOS pair0018–9200/97$10.00©1997IEEEis active,where for high ones only the nMOS pair is in conduction.For“middle”values,both pairs are“ON,”but each with reduced contribution(exactly the half in the“crossing-point”condition).Theconstant-m,is the thermal voltageandA,the supply voltage for theused technology is about1.33V).In Fig.2(a),a feedback circuit which gives an equal valueof transconductance for low and high input signals is shown.Two dummy circuits have been placed operating,respectively,at high(M)and low(M)input levels.Afeedback MOST(M)controls the current in the pMOS inputstage and makes it equal to the nMOS stage one,the transistorsworking in weak inversion.To take into account the inﬂuenceof the slope factor,transistorM has been designed with aslightly higher valueof m).In Fig.2(b),two other feedback loops ensuring a constantsupply voltage by means of sensing the“crossing-point”condition,performed by equal transistorsM andM–M–M–M–M)and a regulating MOST(MM with areference current(ﬂowing onM).The right loop is a voltageregulating system which,by means of an external supplyvoltage(,which can be a battery),controls the internalsupplyvoltage and keeps it constant.In this manner,thewhole circuit is robust to possible discharges of the externalsupply.The feedback circuitry can work with valuesofcomprised in the range1.3–2.2V.For low-input common-mode voltages,only the pMOS inputpair is active and the currentﬂowing on M and M is givenby the drain current ofM().are both“OFF”and no currentﬂowsin,.This(a)(b)(c)Fig.1.(a)Rail-to-rail input stage;(b)transconductance versus input com-mon-mode voltage(nonconstant g m input stage);and(c)transconductanceversus input common-mode voltage(constant g m input stage).total current is kept equalto by means of the feedbackcircuit described in Fig.2(a).Since the input transistors arein weak inversion,the input transconductance is the same forlow-and high-input common-mode voltages.For“middle”values of common-mode input voltages,areduced value of currentﬂows in both the input pairs.Thiscurrent,in the“crossing point”condition,is exactly half ofthe value compared to low and high common inputs.But thetotal currentﬂowing in the input transistors and,consequently,the input transconductance are always the same.The inputvoltage which realizes the“crossing point”condition is strictlylinked to the valueof.In fact,it is about half of it.Thefeedback circuit of Fig.2(b)prohibits the variationsofand,consequently,ﬁxes the“crossing point”condition.(a)(b)(c)Fig.2.(a)Feedback circuit ensuring equal transconductance for low and high input signals,(b)feedback circuit ensuring the crossing point condition and a constant internal supply voltage,and(c)the main schematic of the op-amp.(In the schematics all the MOS have W=1000 m,L=1:2 m except if W is speciﬁed).(a)(b)(c)Fig.3.(a)Microphotograph of the chip,(b)simulated and experimental GBW versus common-mode input voltage,and (c)internal versus external supply voltages.In Fig.2(c),the main schematic of the op-amp is shown.It is formed by the input stage (previously described),a summingstage (MM MAX =6%)Gain Bandwidth (GBW) 1.3MHz (PM =64 )Low frequency gain84dBPower Consumption (total quiescent current in the input stages =10 A;in the output stage =90 A)0.46mW (215 W in the main stage,230 W in the biasing and feedback loops,only 15 W in the regulator)Slew Rate1V/ s Total Harmonic Distortion (1KHz,V pp =60%V AL )1%Equivalent input voltage noise 25nV/pHz (1=f noise negligible)Input offset voltage typical =0.8mV;3 value =60:2mV Settling time0.38 s (1%);0.58 s (0.1%)Overload Recovery 100nsCMRR 56dB @10Hz;52dB @100KHz PSRR +48dB @10Hz;26dB @100KHz PSRR 051dB @10Hz;32dB @100KHz Chip area1.2mm 2III.O P -A MP E XPERIMENTAL R ESULTSThe chip [see photo–Fig.3(a)]has been designed in0.7-m and the threshold voltages about 0.7V.The test of the chip has been done with a testset for automatic characterization of opamps (TACO)[22].Fig.3(b)shows the simulated and experimental gain bandwidth (GBW)versus input voltage.The difference is due to mismatch.Fig.3(c)shows the internal and external supply voltages.From this ﬁgure,we can notice that the circuit is still operating for a minimum external voltage of 1.3V.In Table I,the experimental results are collected (in the operating condition of 1.5-V supply voltage and 15-pF of load capacitance).These values can be considered valid in the supply range 1.3–1.8V.IV.C ONCLUSIONA new way to realize aconstant-[5],“Design of low-voltage bipolar opamps,”in Proc.AACD,Scheveningen,1992,pp.39–59.[6]R.G.H.Eschauzier,L.P.T.Kerklaan,and J.H.Huijsing,“A100-MHz100-dB operational ampliﬁer with multipath nested Miller compensation structure,”IEEE J.Solid-State Circuits,vol.27,pp.1709–1717,Dec.1992.[7]R.Hogervorst,R.J.Wiegerink,P.A.DeJong,J.Fonderie,R.F.Wasse-naar,and J.H.Huijsing,“CMOS low voltage operational ampliﬁers with constant-g m rail-to-rail input stage,”Analog Integrated Circuits and Signal Processing,vol.5,pp.135–146,1994.[8]J.H.Huijsing,K.J.De Langen,R.Hogervorst,and R.G.H.Eschauzier,“Low voltage low power opamp based ampliﬁers,”Analog Integrated Circuits and Signal Processing,vol.8,no.1,pp.49–67,1995.[9]R.Hogervorst,J.P.Tero,R.G.H.Eschauzier,and J.H.Huijsing,“Acompact power efﬁcient3V CMOS rail-to-rail input/output operational ampliﬁer for VLSI cell libraries,”IEEE J.Solid-State Circuits,vol.29, pp.1505–1513,Dec.1994.[10]J.H.Huijsing,R.Hogervorst,and K.-J.DeLangen,“Low voltage lowpower ampliﬁers,”in Proc.ISCAS,1993,pp.1443–1447.[11] E.Seevinck and R.J.Wiegerink,“Generalized translinear circuit prin-ciple,”IEEE J.Solid-State Circuits,vol.26,pp.1098–1102,Aug.1991.[12]R.J.Wiegerink,Analysis and Synthesis of MOS Translinear Circuits.Norwell,MA:Kluwer,1993.[13]J.H.Botma,R.F.Wassenaar,and R.J.Wiegerink,“A low voltageCMOS opamp with rail-to-rail constant G m input stage and a class AB rail-to-rail output stage,”in Proc.ISCAS,1993,pp.1314–1317. [14]J.H.Botma,R.J.Wiegerink,S.L.Gierkink,and R.F.Wassenaar,“Rail-to-rail constant-G m input stage and class AB output stage forlow-voltage CMOS op-amps,”Analog Integrated Circuits and Signal Processing,vol.6,pp.121–133,1994.[15]R.Hogervorst,J.P.Tero,and J.H.Huijsing,“Compact CMOS constant-g m rail-to-rail input stages with g m-control by an electronic zenerdiode,”in Proc.ESSCIRC,Lille,1995,pp.78–81.[16]K.Nagaraj,“Constant-transconductance CMOS ampliﬁer input stagewith rail-to-rail input common mode voltage range,”IEEE Trans.Circuits Syst.II,vol.42,pp.366–368,May1995.[17]J.F.Duque Carrillo,R.Perez Aloe,and J.M.Valverde,“Biasingcircuit for high input swing operational ampliﬁers,”IEEE J.Solid-State Circuits,vol.30,pp.156–159,Feb.1995.[18]J.F.Duque Carrillo,J.M.Valverde,and R.Perez Aloe,“Constant-G m rail-to-rail common mode range input stage with minimum CMRRdegradation,”IEEE J.Solid-State Circuits,vol.28,pp.661–666,June 1993.[19]J.H.Botma,R.J.Wiegerink,and R.F.Wassenaar,“Low voltageCMOS rail-to-rail constant-G m input stages operating in weak and strong inversion,”in Proc.lCECS,Cairo,1994,pp.395–399.[20] C.Hwang,A.Mohamed,and M.Ismail,“Universal constant-G m input-stage architectures for low-voltage op amps,”IEEE Trans.Circuits Syst.I,vol.42,pp.886–895,Nov.1995.[21]R.G.H.Eschauzier,R.Hogervorst,and J.H.Huijsing,“A pro-grammable1.5V CMOS class-AB operational ampliﬁer with hybrid nested Miller compensation for120dB gain and6MHz UGF,”IEEE.J.Solid-State Circuits,vol.29,pp.1497–1504,Dec.1994.[22] C.Van Grieken and W.Sansen,“A testset for automatic characterizationof opamps in the frequency domain,”in Proc.Int.Conf.Measurement and Test Structures,Barcelona,Mar.1993,pp.83–88.。

城轨英语试题及答案详解

城轨英语试题及答案详解一、选择题（每题2分，共20分）1. Which of the following is NOT a type of urban rail transit?A. SubwayB. Light RailC. MonorailD. Bus Rapid Transit答案：D2. The term "metro" is commonly used to refer to:A. A type of underground railway systemB. A type of bus systemC. A type of tram systemD. A type of monorail system答案：A3. What does the acronym "LRT" stand for in the context of urban rail transit?A. Light Rail TransitB. Long Range TransportationC. Local Rail TransportD. Large Rail Transport答案：A4. In which country was the world's first underground railwaysystem opened?A. United KingdomB. United StatesC. FranceD. Germany答案：A5. Which of the following is NOT a benefit of urban rail transit systems?A. Reduced traffic congestionB. Increased air pollutionC. Improved public transportation efficiencyD. Enhanced connectivity within the city答案：B6. What is the primary energy source for most modern urban rail transit systems?A. ElectricityB. GasolineC. DieselD. Coal答案：A7. Which of the following is a safety feature commonly found in urban rail transit stations?A. EscalatorsB. Ticket vending machinesC. Emergency exitsD. Advertising boards答案：C8. What is the term used to describe the process of integrating different urban rail transit lines to allow for seamless travel?A. InteroperabilityB. IntegrationC. CoordinationD. Harmonization答案：A9. Which of the following is NOT a component of an urban rail transit system?A. TracksB. TrainsC. SignalsD. Highways答案：D10. What is the main purpose of an urban rail transit system?A. To provide entertainmentB. To facilitate long-distance travelC. To support urban developmentD. To promote car ownership答案：C二、填空题（每题2分，共20分）1. The _______ system in urban rail transit is responsiblefor controlling the movement of trains to ensure safety and efficiency.答案：signal2. Urban rail transit systems are often designed with _______ in mind to minimize their environmental impact.答案：sustainability3. One of the key challenges in urban rail transit planning is to balance the need for _______ with the available resources.答案：capacity4. The _______ of an urban rail transit system refers to the number of passengers it can transport within a given period. 答案：throughput5. Urban rail transit stations are typically equipped with_______ facilities to assist passengers with disabilities.答案：accessibility6. The _______ of urban rail transit systems can be affected by factors such as population density and land use patterns. 答案：performance7. Urban rail transit systems often serve as a catalyst for _______ development, as they can attract businesses and residents to areas along the transit lines.答案：economic8. The _______ of urban rail transit systems can be enhanced through the use of advanced technologies such as automatic train control.答案：reliability9. Urban rail transit systems are often funded through a combination of _______, user fares, and government subsidies. 答案：public-private partnerships10. The _______ of urban rail transit systems can have a significant impact on the quality of life for residents in the city.答案：availability三、简答题（每题10分，共40分）1. Describe the main differences between a subway and a light rail system.答案：Subways are typically underground systems that operate on exclusive rights-of-way, while light rail systems can operate on street-level tracks and share rights-of-way with other vehicles. Subways usually have higher speeds and capacities, whereas light rail systems are often moreflexible and cost-effective.2. Explain the role of urban rail transit in reducing traffic congestion.答案：Urban rail transit systems can reduce traffic congestion by providing an alternative mode of transportation that can accommodate a large number of passengers. By taking cars off the road, they help to decrease the volume oftraffic and improve overall traffic flow.3. Discuss the importance of safety in urban rail transit systems.答案：Safety is paramount in urban rail transit systems as they carry a significant number of passengers daily. Measures such as regular maintenance, strict safety protocols, and emergency response plans are crucial to prevent accidents and ensure the well-being of passengers and staff.4. What are some of the challenges faced in the operation and maintenance of urban rail transit systems?答案：Challenges include ensuring reliable service despite aging infrastructure, managing increasing ridership demands, maintaining safety standards, and adapting to technological advancements. Additionally, funding for maintenance and upgrades can be a significant challenge, especially in。

北师大版九年级英语Lesson 9 How did they think of that课文和阅读题

How did they think of that?Kids are natural inventors. They often create amazing things from simple ideas. Here are a few examples that might make you wonder, "Why didn't I think of that?"PopsiclesPopsicles were invented by 11-year-old Frank Epperson in 1905. He forgot a drink of juice and left it with a stir stick in it outside on a cold night. The next day it was ice. Because of this he couldn't drink it any more, but he could eat it. It tasted good! These ice sticks became popular among kids at school in summer because they were delicious and helped them stay cool. More than a hundred years later, popsicles are still one of the best summer treats!EarmuffsWhen 15-year-old Chester Greenwood was ice-skating in Farmington, Maine, in 1873, his ears were so cold that he couldn't bear it. Although he tried covering his head in a scarf, it was not comfortable. After some thinking, Greenwood made wire into two circles and asked his grandmother to sew fur on them. He then connected them with a steel headband and the first earmuffs were invented!Crayon holdersWhen 11-year-old Cassidy Goldstein needed crayons for a school project, she had a hard time because there were so many small or broken ones. She found some small clear plastic tubes at home. Although the tiny tubes were usually filled with water to keep flowers fresh, she found that they fit tightly around the crayons. She was now able to hold them easily. This is how she invented Crayon Holders.WristiesWhile some kids just complain when snow gets in their mittens and their hands get wet, 10-year-old Kathryn Gregory decided to do something about it. She created the first pair of Wristies as she wanted to keep her wrists warm and dry. Wrisities are long gloves with no fingers and they are worn under your mittens and coat. They can also be worn by themselves. They help you when you work in the cold because your hands stay warm while you use your fingers. She also started a business, with her parents' help, which she still runs today.All these inventions have one thing in common—the kids were trying to solve problems in their lives. If they can do it, you can do it, too!1.Cause EffectFrank left his juice outside and it became _________________. －﹥He _______________ it and found that it was _____________. He invented popsicles.Chester’s __________ were very _______ when he was ice-skating. －﹥He tried to make earmuffs.Cassidy’s crayons were ___________ and _______________. －﹥It was difficult to use them. She invented crayon holders.Kathryn wanted to __________. －﹥She invented Wristies.。

High-speed rail in Europe experience and issues for future development

Ann Reg Sci (1997)31:21–38Some of the research represented in this paper has been carried out as part of a project “Transport and Regional Development in Europe”in the Transport and the Environment Pro-gramme funded by the Economic and Social Research Council (Grant No L 119251008).It was previously presented at a Workshop at Jo ¨nko ¨ping International Business School,March 1995,and a Workshop on Infrastructure Planning,Spatial Development and the Environment ,Cairns,Queensland,Australia,July 1995.Some of the data reported in this paper comes from various issues of Modern Railways and Today’s Railways magazines.I am grateful for the comments of two referees which have helped improve the argument in this paper.Abstract.The development of High-Speed Rail has been one of the central features of recent European Union transport infrastructure policy.This pa-per reviews the developments which have taken place in a number of coun-tries and assesses the outcome.It identifies the lack of genuine network development which has taken place,criticises the failure to provide a more integrated framework between modes and questions the assumptions of im-proved regional development and cohesion which are claimed for the policy.Instead there is evidence of increasing concentration into the main metropolitan centres served by the emerging network.1.IntroductionThe decisions of the Essen European Council Meeting in December 1994in accepting and extending the views of the Christopherson Committee on the priority Trans-European network projects have reaffirmed the pre-emi-nence of high speed rail projects in the future European high-level network.This paper reviews progress on the high-speed rail network to date and dis-cusses three main issues in their evaluation:competitiveness,network ef-fects and corridor development.The paper is critical of the role assigned to high-speed rail in the overall development,both from the wider European perspective and the point of view of individual regions,and urges caution in approaches to the evaluation of individual projects.22R.Vickerman 2.The development of the European high-speed rail network2.1A European network?The first observation is that there is essentially no European high-speed rail network.The proposals for such a network emerged relatively late,in a re-port of the Community of European Railways(1990)and this was essen-tially adopted as the base for what became the European Community’s pro-posed Trans-European Network for high-speed rail(Vickerman1994;Ross 1994).This“network”is essentially the linking together of a series of na-tional plans for upgraded or very high speed rail improvements which emerged during the1970s and1980s(Fig.1).These emerged for three basic reasons:–to overcome limited capacity on critical links of the rail network,where some new investment was needed and a completely new alignment ap-peared the most cost effective solution–this was essentially the ratio-nale for the first French line,the TGV Sud Est;–to increase speeds on particularly slow sections of the trunk network where the developments in rail technology could not be fully exploited–this was the main reason(along with capacity problems)behind the first two German projects the NBS Hannover-Wu¨rzburg and Mannheim-Stutt-gart and the Italian Direttissima;–to improve the accessibility of more remote regions–this was to a cer-tain extent the rationale for TGV Atlantique and has become an increas-ingly important argument in subsequent proposals,most notably in the case of the first Spanish A VE line,Madrid-Sevilla.Only subsequently has the concept of a European network,using high-speed rail to provide basic international links,become significant.This has initially involved linking together national projects,such as Lyon-Turin or TGV-Est with single corridors,but the only really planned network is the so-called(now rather inaccurately)TGV-North European,also known as the PBKAL(Paris-Brussels-Ko¨ln-Amsterdam-London(Fig.2).Increased in-terest is now being shown in the(genuinely)Northern European network using the various fixed links proposed between Scandinavia and continental Europe linking Germany,Denmark,Sweden and Norway.These two net-works are,however,in very different geographical and economic situations and need to be distinguished from each other.2.2French TGV networkOnly France has developed a genuine network approach to high-speed rail in terms of its Sche´ma Directeur(Fig.3).The initial line,TGV Paris-Lyon was brought into service in stages between1981and1983and thus almost 15years’experience has already been gained.The basic rationale for this line was the inadequacy of capacity on certain critical stretches of line where only two tracks were in operation.The opportunity was taken,fol-lowing a full investigation of alternative options to build a completely newHigh-speed rail in Europe:experience and issues for future development23line.This had the advantage of saving some 120km (about 20%of the dis-tance between Paris and Lyon)and used new technology to develop lighter weight and lighter axle load articulated trains which needed less expensive infrastructure (bridges and tunnels)as they could follow the contours.Paris-Lyon is perhaps the most ideal route for a high speed line,it has to some extent the character of a long distance commuter line.The journey time was reduced to 2h for 450km and has been a particular success in terms of both trip diversion and trip generation.Total rail passengers on the corridor increased from 12.5million in 1980to 22.9million in 1992,18.9million being TGV passengers.This shows traffic diversion,both within the rail mode and to rail,and traffic generation.Most of the increase came in the first few years with 20million rail passengers (15million by TGV)by 1985.Most of the diverted passengers came from air,Paris-Lyon air traffic halved between 1980and 1984,Paris-Gene ´ve fell by around 20%and Paris-Sud Est in general grew at less than half the rate of other radial routes from Paris.Similarly car traffic on the A6parallel motorway grew at only about one-third the rate on the A4and A13routes.Most of the effect 24R.Vickermanof high speed rail was felt within the first few years with virtually stagnant road traffic volumes between 1981and 1985followed by growth at a les-ser rate than on other routes.All modes were affected by a general slow down in growth from 1989onwards.Some half of the additional rail traffic came from newly generated trips.More interesting is the impact on the wider region beyond Lyon,the ability to use the same train for uninter-rupted journeys over the existing network brought about an even greater in-High-speed rail in Europe:experience and issues for future development2526R.Vickerman crease in traffic over these routes compared with the predicted effect,up to twice the expected increase in traffic in the cases of St Etienne,Marseille and Annecy by1984.This wider impact has included the development of through services to Geneva,Lausanne and Bern in Switzerland.1 TGV Paris-Lyon was financed entirely by SNCF on the basis of an ex-pected minimum12%financial rate of return,which has in practice been surpassed.The success of TGV Sud Est in terms of both traffic and reven-ue generation confirmed the French view that high-speed rail was an appro-priate solution and this led to an early decision in favour of TGV-Atlan-tique,with an explicit recognition of the regional development potential which led to a30%government contribution to construction costs.The in-troduction of TGV Atlantique in1990which reduced journey times to Bor-deaux from4hours to3hours led to an immediate increase of around50% in rail travel between1989and1991and a17%reduction in air travel.Following the decision to build the Channel Tunnel,the French govern-ment confirmed the decision to go ahead with TGV Nord,initially to pro-vide an improved Paris-Lille link(reducing journey times from over2 hours to just1hour),but also to provide a through link to the Tunnel(and hence London)and to improve Paris-Brussels and beyond to Amsterdam and Ko¨ln(Holliday et al.1991).The French TGV lines are basically financed by SNCF on the basis of their profitability.TGV Sud Est and Nord have been regarded as finan-cially viable with minimum12%financial rates of return.TGV Sud Est is estimated to be achieving15%in financial terms for SNCF and30%in so-cio-economic terms.This meant it was fully amortised by the end of1993 after only12years in service.TGV Atlantique was assessed viable on the basis of a substantial social rate of return(23%)for which the government paid a direct contribution.The Sche´ma Directeur ranks projects according to rates of return,both financial and social.Very few of these not already determined exceed the expected8%rate of return on SNCF investments and go down to as little as0.1%for TGV Normandie.SNCF regards its TGV investments as hugely profitable taken on their own.TGV Atlantique is reported to be making a net return of22%of the gross revenue after al-lowing for infrastructure costs,rolling stock and direct costs,and TGV Sud Est38%.Rather little discussion has been given to the impact of TGV on the classic network whose deficit has increased due to the diversion of some of the most profitable traffic.TGV Sud-Est has been extended southwards past Lyon and TGV Medi-terrane´e will lead to the coast with spurs joining up with the Spanish sys-tem towards Barcelona and the Italian system towards Torino.TGV Atlan-tique is also likely to extended southwards to Bordeaux and upgrading south of Bordeaux will also provide a link into Northern Spain.Two other likely links are TGV Rhin-Rhoˆne(Lyon-Strasbourg)and TGV Est(Paris-Strasbourg).TGV Est achieves a very low rate of return(originally esti-1For a fuller discussion of the wider impacts of the development of TGV see Plassard(1991, 1992)and for more detail,Plassard and Cointet-Pinell(1988).High-speed rail in Europe:experience and issues for future development27 mated at4%in financial terms for the entire project)and this has led to some recasting of the project.The announcement of the project’s De´clara-tion d’Utilite´Publique in early1996,which enables land purchase,etc to proceed suggested an even lower financial return.The importance of this project has led to commitments of investment for the regions concerned and guarantees from the State.TGV Rhin-Rhoˆne is also estimated rather below the key8%figure,though possibly higher than TGV Est,raising a question over the possible order of proceeding with these two projects. These are seen as key international links because they provide connections between the French and German systems linking to both Frankfurt and Stuttgart,as well as to Luxembourg,and hence providing links between some of the most dynamic regions of Europe over recent years.It seems unlikely that any more of the proposed links will actually come to fruition, despite the political pressure to be on the TGV networks shown by most French regions.2.3German ICE networkThus far the German high speed rail network,based on its ICE train,has been mainly aimed at overcoming particular bottlenecks in its existing net-work(Fig.4).This contrasts with the French approach which has largely constructed a parallel network,using the existing network for access to the major cities where new construction would be difficult.Two separate lines have been brought into service so far,Mannheim-Stuttgart and Hannover-Wu¨rzburg.These both serve the main north-south routes.The next planned routes are Hannover-Berlin and Ko¨ln-Frankfurt am Main.The first of these is a key link in the revised transport plans following unification,involving a mix of upgrading and new construction,and is due for completion in 1997/98.The latter has been planned for some time,and construction started in1996for completion in2000.This could also be viewed as an important extension to the PBKAL international network bringing Frankfurt within four and half to five hours of London.There is a further wish list of routes identified in the1992Bundesverkehrswegeplan,principally Stuttgart-Augsburg and Mu¨nchen-Nu¨rnberg-Berlin,but it is becoming increasingly doubtful how much of this will be achieved.Two other features of the German approach are relevant.First,there has been an associated set of improved routes in addition to the new lines,pro-viding for speeds of200km/h.Secondly,parliamentary approval has been given for a completely separate development,that of the Transrapid maglev on a route between Hamburg and Berlin.This magnetic levitation system, driven by long stator drive,requires a completely new infrastructure which is incompatible with existing rail,and thus must either be provided with connections at new termini on the edge of the cities or be driven at very high cost to new termini in city centres.The scheduled date of completion is2005,but there remain many financial and technical problems.The German new lines have been much more expensive than the French lines.Due to more difficult terrain(they are replacing difficult old lines28R.VickermanÐÐÐÐthrough mountainous terrain),they have required a high proportion of line in tunnel.Secondly they have been designed for multi-purpose use,by the very high speed ICE trains at250km/h,by traditional IC trains running at 200km/h and by freight trains running at lower speeds,but requiring more expensive engineering.The urban structure of Germany lacks the mono-centric focus of France.Inter-city rail transport has for many years been based on a complex interlinking network of services with interchanges which provide regular interval hourly or two-hourly connections between most major German towns and cities,and more frequent operations on cer-tain key links.This makes it difficult to identify the impact of high speed rail in quite the same way as in France.In the first five years of operation ICE passen-gers more than doubled from just over10million to nearly23million andHigh-speed rail in Europe:experience and issues for future development29 ICE traffic accounts for28%long-distance passenger revenues.Deutsche Bahn estimates that some12%of this traffic is diverted from road and air. Both of these are rather lower figures than would be implied from French evidence suggesting that the rather more patchy introduction of high-speed has not had the marked shift in patterns of usage as experienced from the more concentrated introduction of TGV on all new lines in France.German transport policy has identified the need to effect a shift from road as a key element such that proposed rises in fuel prices will be used to maintain high levels of investment.The usefulness of continuing to invest in high speed rail just to provide competition with road and air is being questioned however.This is seen as an expensive solution which may not make the environmental gains which could be achieved with a more restrictive approach to road transport(for example,see the discussion in Whitelegg 1993).As in the case of France,there are also international links with German ICE trains running through to Switzerland,Basel and Zu¨rich,and there are plans for through services to Belgium and the Netherlands.There has been less interest in a specifically international network,however.2.4Italian direttissimaThe Italian solution has been rather more like the German one,investing in new lines to overcome particularly difficult stretches of route.In this case the train technology has also been important using,as an interim develop-ment,the ETR450/460tilting trains,Pendolino,which enable higher speeds on existing track prior to the introduction of the ETR500very high speed trains on new dedicated track.A similar solution was tried in Britain in the1970s to overcome the need for new construction.In that case the active tilting mechanism proved both technically troublesome and uncom-fortable for passengers and was abandoned.The Italian system has proved similarly troublesome on introduction on through services to Switzerland due to more frequent and tighter curves on these routes.The proposed Italian network is T-shaped with an east-west route along the Po valley and a north-south route linking Bologna with Roma(of which the Firenze-Roma section is in operation)and eventually Napoli. The link between Torino and Lyon is the major international link already discussed although a potentially important additional development is that of the Brenner route,though not involving very high speed.2.5Spanish AVEThus far there is a single high-speed rail route between Madrid and Sevilla. Like the French routes,this overcomes capacity problems on an existing route and also achieves a substantial reduction in distance by taking a more difficult,but more direct,route.The decision to go ahead was taken very quickly in1986–87,mainly to ensure the new service was in operation by the Sevilla Expo in1992.The A VE is interesting in that is bought in tech-30R.Vickerman nology rather than developing its own as in the French,German and Italian cases,but did this by marrying French traction technology with German signalling.Like the German NBS,the new route is used by conventional trains running at200km/h(using German built locos)as well as the 280km/h A VE.This was to ensure through services to points such as Ma-laga off the new network.Unlike the French case,the A VE cannot provide through service because it is built to standard European1435mm gauge, whilst the classic network in Spain is to a broader1676mm gauge.Trains with specially adjustable bogies maintain these services.The A VE has been remarkably successful in terms of traffic growth and diversion.After two years operation traffic was3.55million passengers. Note that total traffic is still very small in comparison to the volumes car-ried on TGV Sud Est and TGV Atlantique,suggesting a relatively low rate of return.Again air traffic has suffered with an estimated60%reduction. Some32%of travellers have diverted from air,25%from car and26% were newly generated,but again existing train services have suffered with a 14%of A VE passengers having switched.As well as the long distance ser-vices to Cordoba and Sevilla,new markets have been created with an A VE Shuttle service to Ciudad Real and Puertollano around200km from Madrid.The long term plan is to provide new lines between Madrid and Barce-lona with a northerly spur towards San Sebastian.Madrid-Barcelona is an obvious high speed rail route(though rather longer at over700km than the ideal for such routes)given the size of the cities,but the real significance is to provide a standard gauge link with the French network to enable ea-sier through journeys between Madrid and other major cities such as Lyon, Paris,Milano.2.6Other high-speed rail developmentsThe French,German,Italian and Spanish cases are those involving major new construction to enable very high speed(250km/h or over)operation. The only other current construction of such a route is the extension of the French TGV Nord to Brussels,which should be in full operation by1997. Beyond Brussels a mixture of new construction and upgrading will en-hance the routes through to Amsterdam and Ko¨ln.The extension of TGV Nord to London will be discussed in more detail below.However,a number of other countries have been pursuing the develop-ment of higher speed(200–250km/h)operation with minimal new construc-tion.The major success has been that of the British diesel InterCity125 (125miles/h=200km/h)which laid the foundation for the commercial suc-cess of the InterCity network achieving a no subsidy operation during the 1980s and led to the electrification of the East Coast Main Line on the basis of225km/h operation by electric trains.This enables the433km between London and Newcastle to be achieved in2h45m to3h.For comparison Paris-Lyon Part Dieu,427km,takes2hours,Madrid-Sevilla,472km,takes 2h15m to2h25m and Hannover-Nu¨rnberg,430km takes2h55m.In Sweden the X2000tilting train has provided the same basis for ac-celerating services on classic lines with speeds up to200km/h.Banverket, the Swedish rail infrastructure authority,has so far concluded that the addi-tional benefits from implementing a new high speed network for the south-ern trunk routes in Sweden may not sufficiently outweigh the extra costs given the relatively marginal gains in time.2.7Issues from the experiences in EuropeUndoubtedly,the introduction of high-speed train services on new tracks serving major cities has been seen to have been a major success.Probably without the phenomenal growth of traffic on Paris-Lyon experienced in its very early years there would have been no rapid expansion in the French network and this would have limited the possibilities for a European net-work.However,it has to be recognised that there are very specific circum-stances surrounding the original TGV project in France,which are not ne-cessarily transferable to other projects either in France or in other European countries.Urban structure is clearly important,the first three TGV lines link Paris with the four major provincial urban centres,Lyon,Marseille,Bordeaux and Lille.In the case of Lyon and Bordeaux the existing best rail times made daily return journeys unattractive,but clear thresholds were overcome in bringing journey times down to around2h and3h respectively.It thus appears important to consider high speed rail in the context of linking large urban centres(at least0.75million inhabitants)at distances of400–750km, capable of generating flows of around12–15million passengers a year by rail at a minimum.Lille is the odd case out here at227km,but this has to be considered in the wider context of Brussels(340km from Paris)and London(500km via Lille and the Tunnel).Secondly,access to alternative modes is important.Air is disadvantaged at Lyon due to the position of Satolas Airport(27km from Lyon with no rapid transit connection).Orly and Roissy-Charles de Gaulle also have rather poor direct links onto the Paris RER networks.Thirdly,the ability to serve a wide area with trains using the new infra-structure has proved significant in extending the market.TGV Sud Est serves a network of2510km on the basis of new infrastructure of just 540km(including the Rhone-Alpes extension to V alence opened in1994) and Atlantique2440km from just282km of new line.The three lines in service provide TGV trains to well over half the population of France. Although many of the other places are not major generators of traffic,they provide enough to help utilise both the infrastructure and the fleet in a more optimal way,increasing the financial return on the investment.Fourthly,although the French lines have been seen to be largely fi-nanced on the basis of SNCF’s own investment criteria,it has been sug-gested that there are substantial socio-economic returns on top of the purely financial.These derive partly from the benefits to other modes of transport in terms of the reduction of congestion and accident costs on roads and ofcongestion at airports and in overcrowded airspace.Regional authorities see there being further benefits in terms of the enhanced image and accessibil-ity of cities which will have a direct effect on investment and business de-velopment.Such effects are clearly not automatic–SCNF invested in two intermediate stations on TGV Sud Est which have proved to be neither ma-jor traffic generators nor resulting in local economic growth.Such growth has however occurred at other stations such as Valence,where a major plan to redevelop the station area was undertaken as a result of the coming of TGV.This success has led to major urban redevelopment plans in associa-tion with the other new lines,most notably at Rennes and,particularly, Lille.It has to be admitted that there are few other parts of Europe where the precise configuration of circumstances satisfies these criteria.The German situation is complicated by a rather different urban structure of many more medium sized cities and more complex interactions which leads to the needs for a dense network of services which cannot be tailored to demand in the precise way the French network is.There the domination of Paris-based journeys enables the trains to be loaded as fully as possible and to use a peak pricing system to match supply and demand.In Germany the provision of long through journeys,Hamburg-Mu¨nchen or Basel and Ber-lin to Frankfurt and Mu¨nchen,makes it difficult to relate price to capacity on any one link of the journey.The smaller size of both cities and network served in the Spanish case is shown by the much lower traffic figures.Thus we need to consider carefully the likely issues in the evaluation of high speed rail rather carefully under the headings of competitiveness,the network and regional development considerations.petitiveness of high-speed railHigh Speed Rail(HSR)needs to be considered as not making just a mar-ginal change to relative speeds and generalised costs within the transport system.Most transport demand forecasting models work from the basis of relatively marginal changes and an assumption that traffic can be assigned to the least(generalised)cost route(though see Blanquier1996,for an al-ternative approach).The nature of HSR is both that it has substantially dif-ferent characteristics from conventional rail and that it affects competition with both road(private car)and air,and thus is more likely to have a non-marginal effect.This renders less likely the ability to use simple demand forecasting models which are based on the(usually rather low)own and cross-price elasticities for rail travel(Quinet and Vickerman1996).Experience with the French TGV(e.g.Plassard1991)suggests,as we have seen above,that traffic generation is much greater than would nor-mally be expected.This is not necessarily a monotonic relationship how-ever,there is clear evidence of thresholds.These are typically time thresh-olds which relate to the lower and upper bounds of the distance/time “window”where HSR has a clear advantage.These thresholds are of theorder of one to three hours by HSR representing distances of200–600km. At shorter distances the flexibility and lower access-to-network times of car make it difficult for rail to complete,at longer distances the faster line-haul speeds of air can overcome the higher access-to-network and inconvenience factors in air travel.Paris-Lyon journeys increased by150%in four years after the introduction of TGV services,a figure consistent with a reported 200per cent increase in travel during the first ten years of operation on the first Japanese Shinkansen,the Tokaido line(Plassard1991).Nevertheless French experience suggests there are important market gains over longer distances where,although smaller in absolute terms,the relative increase in market size and share is greater.This suggests the need to separate out carefully the business traffic which dominates the former category and discretionary leisure travel(with higher elasticities)which dominates the latter.Although there is a tendency to think in terms of time,and time thresholds, there is clearly subjective evidence relating to the comfort/convenience factor. City centre to city centre travel by a single mode with higher comfort charac-teristics than either car or rail has difficult to quantify advantages.However,it is still true that many journeys do not both begin and end at the relevant city centre,e.g.they are home to business appointment. Homes may often be better sited with respect to airports than to city centre rail stations.Likewise,many modern businesses are situated in peripheral locations(often dictated by airport access).This suggests important consid-eration needs to be given to the quality of the access network.For forecast-ing and considering competition the key issue is to include the pattern of total journey times.work considerationsNetwork considerations relate to two key inter-related issues;the character-istics of the HSR network itself and of access to the HSR network.The HSR network characteristics relevant are the size of the network and the frequency of stops(this latter point relating to the second dimen-sion of access to the network).Although single line HSR links are feasible where there are substantial traffic generators,depending on construction costs they needs to generate12–15million passengers a year to be viable. Typically greater traffic volumes and hence rates of return will be obtained where there is the possibility of the HSR route being integrated with the rest of the network to provide through services.These are more likely to serve the more elastic discretionary travel markets.Again French experi-ence with the initial TGV-Sud Est confirms this point and plans for Euro-star North of London services is based on the desire to capture a similar market.The search for increased markets also leads to examination of intermedi-ate stops along HSR routes.These,however,carry an important trade-off between tapping new markets and losing market share in the major markets。

九年级英语下册Unit2Robot语言知识点归纳牛津版

Unit 2 Robot一.教课内容：Unit 2 Robot二.教课目：本元、短和言点知【详细教课程】（一）要点complaint n.投；诉苦complain vi.投；诉苦post vt.寄laundry n.洗衣物,洗衣店iron vt.熨n.熨斗；sweep vt.打，清salesman n.售；推everyday adj.平时的，每日的dustbin n.垃圾箱mess n.杂乱，乱spread vt.使散布，睁开，散smooth adj.圆滑的，平展的rubbish n.垃圾，物dry adj.干的vt.（使）干；（把⋯⋯）弄干nod v.点either adv. /pron.也;二分之一copy n.一本(份、册)；副本vt.抄录；复制；复印；模拟order n.定untidy adj.不整的稳固：在以下句子中填上适合的使句意完好。

1. Mr. Jiang is a _________________ and works in Moonlight Town.2. The robot ____________________ Mr. Jiang’s shirts yesterday.3.The robot would do the _______________________ for Mr. Jiang.4.A few weeks later the robot caught a ______________________.5.The robot threw the clean shirts in the ____________________.6.Sometimes the robot would ___________________ things over.7.Mr. Jiang found his flat in a ____________________.8.Having a robot was just too much _____________________.9. He ___________________ _ to me with a smile and said,“Hi!”.10.I haven’t been to Beijing,Tom hasn’t been to Beijing, ______________ ________.（二）要点短：1.在好多方面in many ways2.了做某事 in order to do sth.3.使蒋的生活更简单了make Jiang ’s life much easier4.蒋衫iron Jiang’ s shirts5.蒋准午饭盒 make a lunch box for Jiang6.果 as a result7.不再 no longer/not any longer8.需要早起 need to get up early9.在上班 be at work10.洗子 wash the dishes11.整理床 make the bed12.下班回家 return home from work13.跟新的一干 be as clean as new14.准好 be/get ready for15.⋯⋯很意be happy/satisfied with⋯16.染上病毒 catch a virus17.把⋯⋯返回机器人商铺return sth. to the robot shop18.叫醒蒋 wake Jiang up19.四 move around20.撞翻西 knock things over（三）言点知：1. Mr. Jiang is the first person in Sunshine Town to own a robot.（L.2 ）①o wn 用作及物动词 , 表示“拥有”的意思他拥有这辆车。

SATK系列热接口单元，即时家用热水产生说明书

SATK series heat interface unitInstantaneous domestic hot water productionCode SATK16315FunctionThe SATK series HIU allows independent control of heat regulation and domestic hot water production within centralised heating systems.Product rangeSATK16315 H igh-temperature heating HIU, instantaneousdomestic hot water production, mechanical control, equipped with 30kPa differential pressure regulating valve, zone valve and thermostatic mixing valve.Size (mm)Characteristic components1 -DHW priority valve2 -Air vents/draining3 -Brazed exchanger4 -Proportional modulating valve with manual pre-set5 -Di erential pressure regulating valve (30 kPa)6 -M10 x 1 connection for heat meter temperature probe7 -Strainer8 -Zone valve with pre-setting 9 -Thermostatic mixing valve10 -Heat meter template L = 130 mm.Primary circuit ow Primary circuit return Domestic hot water outletHeating circuit ow Heating circuit returnDomestic cold water inletTechnical specifications Materials Frame: galvanised steel Exchanger:brazed stainless steelConnection pipes: copperComponents:brass EN12165 CW617NPerformance Medium: water, max. 30 % glycol Maximum medium temperature: 85 °C Max. working pressure: - primary circuit:PN 10 bar-domestic circuit:PN 10 barNominal DHW exchanger capacity: 40 kW DHW circuit flow rate: min. 1,8 ± 0,3 l/minmax 18 l/min Heat interface units connection:primary circuit: 3/4”heating circuit: 3/4”DHW circuit:3/4”SATK16315Primary flow rate pre-adjustmentSATK16315 provides mechanical proportional regulation, so the supply flow rate to the exchanger (primary) increases as the DHW draw-off flow rate (secondary) increases.It is possible to vary the regulation characteristics according to the primary medium temperature in order to limit the return temperature as much as possible without affecting the performance on the utility side.G (l/h)Q (l/min)800600400200Domestic hot water circuit flow rateP r i m a r y c i r c u i t f l o w r a t eSATK16315Hydraulic characteristics of the proportional regulationConstruction detailsAnti-scale materialsThe materials used in constructing the mixing valve were selected to eliminate seizing due to limescale deposits. All functional parts have been made using a special anti-scale material with low friction coefficient, which ensures over time performance.Thermal shut-offIn the event of accidental cold water supply failure, the obturator shuts off the hot water passage, thus preventing the delivery of mixed water. This is only guaranteed when there is a minimum temperature difference between the inlet hot water and the mixed water delivery of 15 °C.MAX MINAPrimary circuit return temperatureOperating principleThe thermostatic mixing valve mixes the hot and cold water at the inlet so as to maintain the mixed water constantly at the set temperature at the outlet. A thermostatic element (1) is fully immersed in the mixed water flow (2). It contracts or expands, moving an obturator (3) which controls the passage of hot (4) or cold (5) water at the inlet. If the inlet temperature or pressure changes, the internal element automatically reacts to restore the set temperature at the outlet.Primary T DCW - DHWFlow rate DCW - DHWFlow rate °C °Cl/min °Cl/min 5510–4512,810–508,76015,912,16518,515,07020,317,67522,219,38024,120,9DHW production performance DHW productionSATK16315 has a 5219 series thermostatic mixing valve with an adjustable set temperature from 35 to 65 °C. This mixing valve also features a thermal shut-off function that operates if there is no cold water at the inlet.Primary temperature 60 °C - DCW 10 °CP r i m a r y r e t u r n t e m p e r a t u r ePrimary temperature 70 °C - DCW 10 °CPrimary temperature 80 °C - DCW 10 °C30,035,0Domestic hot water flow rate (l/min)20,025,010,015,0P r i m a r y r e t u r n t e m p e r a t u r e°CDomestic hot water flow rate (l/min)P r i m a r y r e t u r n t e m p e r a t u r e°C Domestic hot water flow rate (l/min)2020015010010255001000Δp2050G (l/h)100100020050020005000100100012005000,51023520005000Δp 203050G (l/h)100501000200300500200030005000Δp(mm w.g.)10,510235Δp (kPa)203050100501000200300500200030005000Hydraulic characteristicsDomestic function / Exchanger secondaryHeating functionCaleffi S.p.A.S.R. 229, no. 25 · 28010 Fontaneto d’Agogna (NO) - Italy - Tel. +39 0322 8491 · Fax +39 0322 863723****************·© Copyright 2019 CaleffiWe reserve the right to make changes and improvements to the products and related data in this publication, at any time and without prior notice.SPECIFICATION SUMMARYCode SATK16315Two-way satellite for high temperature, with instant domestic hot water production. Complete with: domestic priority valve, mechanical modulating valve with manual pre-set, plate exchanger, differential pressure regulating valve with fixed setting of 30 kPa, thermostatic mixing valve with adjustable thermal shut-off (35–65 °C), primary strainer, zone valves with ON/OFF thermo-electric head. Dimensions 420 x 450 x 200 mm. Medium: water, maximum percentage of glycol 30 %. Maximum medium temperature 85 °C. Maximum working pressure 10 bar, domestic circuit 10 bar. Nominal DHW exchanger capacity: 40 kW. Domestic circuit flow rate: min. 1,8 ± 0,3 l/min. Maximum pressure difference: 2 bar. Materials: components made of brass EN 12165 CW617N; connection pipes made of copperDifferential pressure regulating valveFinishing accessoriesSATK16315 has a differential pressure regulating valve with a fixed setting of 30 kPa. This device ensures that the satellite performance does not vary with the upstream differential pressure conditions. This parameter is nut fully under control in variable flow rate systems, and can sometimes cause discomfort, noise and excessively high flow rates.The differential pressure regulating valve is a dynamic balancing device that “cuts” any excessive head that the product or downstream system do not require for operation.painted sheet metal cover (without insulation)painted sheet metal cover (with insulation)789515789516Code Utilisation789painted sheet metal cover for SATK16 and closed-cell expanded PE-X insulation.Minimum insulation thickness: 10 mm.Reaction to fire (DIN 4102):class B2.。

NSS Mastering Biology Suggested Answer Book 1B (eng)

Suggested answers to Exercise and Reading to learn(Note: The overseas examination boards bear no responsibility for the suggested answers contained in this publication. Answers for HKCEE and HKALE questions are not available due to copyright restrictions.)Chapter 7 Gas exchange in humansExerciseMultiple-choice questions (p. 7-26)1 D2 B3 C4 C5 C6 B7 B8 A9 C10 C11 DShort questions (p. 7-28)12The dust particles and bacteria from the air cannot be filtered by cilia or trapped by mucus.1m They can go directly into our lungs. 1m The dust will block the air passage and the bacteria will cause respiratory infection. 1m13 a Air sacs 1mb Nasal cavity 1mTrachea 1mBronchi 1mBronchioles (except the smallest ones) 1mc Intercostal muscles 1mRibs 1mDiaphragm 1m 14 a In sequence:upwards / outwards 1mdownwards / flatten 1mb i On diagram:Oxygen arrow to blood from air and CO2 arrow to air from blood 1mOxygen arrow to red blood cell 1mCO2 arrow from plasma 1m ii Diffusion 1miii Large surface area 1m 15 HKCEE Biology 2005 I Q416Structured questions (p.7-29)17 a B and C 2mMucus traps dust. 1mCilia beat mucus up the trachea,preventing it from entering the lungs. 1mb F, G and H 3mc E, air sac 1m x 2It is the site of gas exchange between air and blood. 1m 18 a General description of pressure changesDecreases to a minimum of –0.29 / –0.3 / –0.31 kPa 1mat 0.8–0.9 s 0.5mThen returns to zero at the end of inspiration 1mat 1.62–1.7 s 0.5mb Changes from –0.29 / –0.3 / –0.31 kPa to 0.29 / 0.3 / 0.31 kPa 1mOverall change of 0.58–0.62 kPa 1mc i Contraction of diaphragm and intercostal muscles 1mIncreased volume in thorax / chest, decreased pressure 1mPressure rises as air moves in 1m ii Relaxation of diaphragm and intercostal muscles 0.5m Reference to elasticity / elastic fibres 0.5mDecreased volume in thorax / chest, increased pressure 1mPressure decreases as air moves out 1m 19HKCEE Biology 2001 I Q4b20HKCEE Human Biology 1999 I Q1b21 a1mb Hydrogencarbonate indicator / lime water 1mc A: Hydrogencarbonate indicator changes to yellow / lime water turns milky 1mB: Hydrogencarbonate indicator remains orange / lime water remains clear 1md i Collect a jar of atmospheric air as inhaled air. 1mCollect a jar of exhaled air by blowing slowly into a gas jar over water. 1mLower a burning candle into the jar of inhaled air and the jar of exhaled air. 1mRecord how long the candle can burn in each jar. 1m ii The candle can burn longer in the jar of inhaled air. 1mIt is because some oxygen of the inhaled air is absorbed in the lungs and theexhaled air contains less oxygen. 1m 22 a i Arrow at peak of curve 1mii Intercostal muscles contract 1m Diaphragm contracts / flattens / moves down 1mRibs move upwards and outwards 1m iii Line goes up 1mb i Bronchiole 1mii Mucus traps dust / microorganisms 1m Cilia sweep mucus away from air sacs 1m iii Any two from: 1m x 2 Stimulates mucus-secreting cells / excess mucus producedInhibits ciliaLeads to cancerEssays (p. 7-31)23CartilageIn trachea / bronchi 0.5mHolds airway open / prevents collapse 0.5mLow resistance to air movement 0.5m Ciliated epithelium / ciliaSweep mucus 0.5mRemove particles from lungs 0.5m Mucus-secreting cellsSecrete mucus 0.5mTrap bacteria / dust / pollen / particles 0.5m Blood vesselsSupply oxygen / nutrients to tissues of lung 0.5mSurround air sacs / good blood supply to air sacs 0.5mDeliver carbon dioxide / pick up oxygen 0.5mReference to wall of capillary being thin 0.5mEase of / rapid gaseous exchange OR short diffusion pathway 0.5m Smooth muscleAdjust size of airways in exercise 0.5m EpitheliumThin wall of air sacs 0.5mEase of / rapid gaseous exchangeOR short diffusion pathway 0.5mReference to larger surface area of numerous air sacs 0.5m Quality of written communication 2m24Any three from: 1m x 3 Inhaled air contains more oxygen than exhaled airInhaled air contains less carbon dioxide than exhaled airInhaled air contains less water vapourRelative amount / percentage of nitrogen also changesExplanation:Respiration results in lower blood oxygen / higher blood carbon dioxide 1m Oxygen enters blood / carbon dioxide leaves blood in air sacs 1m by diffusion 1m Water vapour diffuses from moist surface 1m Breadth of knowledge 2m max Quality of written communication 1m max Reading to learn (p. 7-32)1During inhalation,diaphragm muscles and intercostal muscles contract. 1m Diaphragm flattens and rib cage moves upwards and outwards. 1m Volume of thoracic cavity increases and pressure decreases. 0.5m Air rushes into the lungs. 0.5m During exhalation,diaphragm muscles and intercostal muscles relax. 1m Diaphragm returns to dome shape and rib cage moves downwards and inwards.1m Volume of thoracic cavity decreases and pressure increases.Air is forced out of the lungs. 1m2The iron lung was connected with a pump which changed the pressure inside. 1m When the pressure inside the iron lung is lower than that inside the lungs of the patient, air rushes into the lungs. 1m When the pressure inside the iron lung is higher than that inside the lungs of the patient, air inside the lungs is forced out of it. 1m3Advancement in the making of artificial joint 1m Reduces risk of allergy allows patients to move more flexibly 1m (Accept other reasonable answers)Chapter 8 Transport in humansExerciseMultiple-choice questions (p. 8-31)1 C2 D3 B4 A5 B6 B7 A8 B9 C10 B11 B12 BShort questions (p. 8-33)13 a i Haemoglobin 1mii Carries oxygen / forms oxyhaemoglobin 1m from lungs to tissues 1mb No nucleus / biconcave disc 1m14 HKCEE Biology 2006 I Q115 a Blood flows twice through heart 1mper one full circulation 1mORPulmonary circulation / to lungs 1mSystemic circulation / to the body 1mb Any one from: 1mMore oxygen reaches tissues / cells OR more efficient supply to tissues / cellsHelps sustain high blood pressureLess resistance to flowEasier to return blood to heartMore rapid circulationGreater activity possibleToo high a pressure does not damage lungs16HKCEE Biology 2001 I Q3bStructured questions (p. 8-34)17 HKCEE Biology 2005 I Q8a18 HKCEE Biology 2004 I Q3c19 a As the total cross-sectional area of vessels increases (due to branching of arteries intoarterioles) / large number of capillaries 1mResistance to blood flow increases and blood pressure falls 1mORFormation of tissue fluid at the arterial end of capillary beds 1mDecreases blood volume and therefore decreases blood pressure within the capillarybeds 1mORGreater distance from heart 1mPressure gradually reduces with distance from heart / pressure is maintained by smalllumen of the arteries 1mORVeins have a larger lumen 1mLarger volume equals decreased pressure 1mb Any two from: 1m x 2The arteries have a thick wall (particularly the tunica media) to resist pressureThe arteries contain numerous elastic fibresElastic fibres allow expansion under pressureSmall arterial lumen ensures high pressurec Any two from: 1m x 2The veins have a large lumen to reduce the resistance of blood flowing into themVeins rely on the movement of surrounding muscle tissue to move blood alongThey possess valves to prevent backflowDescription of how valves workd i Tissue fluid forms at the arterial end of capillary networks because of the highblood pressure. 1m ii Reabsorption at the venule end is brought about osmotically because of the lower solute potential provided by the retained proteins. 1m20 a Pulmonary artery 1mb S ➝ D ➝ C ➝ P ➝ X ➝ Q ➝ B ➝ A ➝ R(2m for all correct answers or no marks)c R has a thicker wall than S. 1mR has a smaller lumen than S. 1md Blood in R has more oxygen / less carbon dioxide / more glucose than in S. (any 2)1m x 2e The semilunar valves are closed. 1mThe cardiac muscle of A and C relaxes. 1mThe pressure inside A and C is lower than the pressure in P and R. 1m Essay (p. 8-35)21Any 10 from: 1m x 10 Highest pressure is in the aorta / arteries / closest to heart, where there is rhythmic rise and fall / pulse.Pressure drops progressively from arteries to arterioles.Pressure drops further through capillaries / progressive drop with increased distance from heart.Pressure in veins is low.(Marks of the above points may be awarded on annotated graph)Rise and fall in aorta or arteries corresponds to contraction of ventricles.Friction with walls causes pressure drop.Arterioles have large total cross sectional area. Capillaries give even greater crosssectional area.Few vessels subdividing into many smaller vessels, causing substantial pressure drop from arterial values / narrow lumen increases friction so pressure drops.Effect depends on whether arterioles are dilated or constricted / reference to elastic recoil in artery walls / maintains pressure.Pressure also drops in capillaries because of leakage of fluids into tissues.Pressure in veins / away from heart is non-rhythmic because influence of ventricles has been dissipated.Pressure in veins can be increased by squeezing action of (skeletal) muscles.This works because of the presence of valves in veins.Reading to learn (p. 8-36)1Blood is returned to the heart from different organs through blood vessels, instead of being used up as suggested by Galen. 1m Blood cannot flow from one ventricle to the other through pores in the septum of the heart, because there is no pore in the septum. Blood flows from one ventricle to the other through blood vessels. 1m 2Some of the deoxygenated blood in the right atrium and ventricle will bypass the lungs.1m Blood in the right atrium and ventricle directly goes to the left atrium and ventricle and pumped to different parts of the body. 1m Organs and tissues cannot get enough oxygen supply from the blood. 1m 3Harvey used careful calculations and repeated experiments to show blood was not used up, but flowed in a closed loop. 1m He dissected the septum of the heart to show it contained no pores. 1m 4Yes, scientists should be skeptical of other people’s findings. 1m Though Galen’s idea remained unchallenged for over 1000 years, Harvey was skeptical of the idea and did experiments to prove that it was wrong. Because of his skeptics and hard work, he finally worked out the correct theory of blood flow 1mChapter 9 Nutrition and gas exchange in plants ExerciseMultiple-choice questions (p. 9-23)1 C2 B3 C4 D5 D6 C7 C8 D9 A10 AShort questions (p. 9-25)11 a photosynthesis, autotrophs 0.5m x 2b Minerals, deficiency diseases 0.5m x 2c photosynthesis, respiration 0.5m x 2d Oxygen, carbon dioxide 0.5m x 2e compensation point, respiration 0.5m x 212 HKCEE Biology 2005 I Q8b13 a Any one from: 1mLongThin cell wallLack of waterproof layer / cuticleLarge surface areaPresent in large numbersMembrane proteins / carriers / channelsMany mitochondriab Active transport / diffusion 1mc The water potential of soil water is usually higher than that of the root cells.0.5mWater moves down the water potential gradient into the root cells by osmosis 0.5mthrough the channel proteins / differentially permeable cell membranes and 0.5mthe freely permeable cell walls. 0.5m 14 a D (mesophyll cell), E (air space) and F (guard cell) 0.5m x 3There are many air spaces to allow diffusion of gases on the moist surfacesof mesophyll cells. 1mGuard cells control the opening of stomata, which allow diffusion of gases. 0.5mb A (cuticle) and F (guard cell) 0.5m x 2Cuticle is impermeable to water. 0.5mGuard cells control the opening of stomata, which allow diffusion ofwater vapour. 0.5m 15 a Area of the field of view= 0.1 mm (height) ⨯ (5.7 cm / 3.4 cm ⨯ 0.1 mm) (length)= 0.0168 mm21mStomatal density= 4 stomata / 0.0168 mm2≈ 238 stomata per mm2 of the leaf surface 1mb Sorghum grows in dry conditions. 1mIt loses water through the stomata rapidly. 1mHaving few stomata can reduce water loss and hence conserve more water. 1m16 a To carry out photosynthesis. 1mT he cells locate near the top of the leaf so that they can trap the maximum amount oflight for photosynthesis. 1mThe cells are densely packed and contain many chloroplasts. 1mb BuoyancyStorage of oxygen / carbon dioxide / gasesAllows rapid diffusion of gases(any 2) 1m x 2c To enable exchange of gases. 1mIt would let in water if stomata are in lower epidermis. 1m Structured questions (p. 9-26)17 HKALE Biology 1998 I Q9a18 HKCEE Biology 2004 I Q4c19 HKCEE Biology 2005 I Q9Essay (p. 9-27)20Plants need to obtain oxygen and carbon dioxide from the atmosphere for respiration and photosynthesis respectively.They also need to obtain water and minerals from the soil for the production of different substances they need. 1m Carbon dioxide and oxygen:Plants exchange gases with the environment by diffusion. In terrestrial plants, gasexchange takes place through leaves, stems and roots.In leaves, gases from the environment diffuse into the air space through the stomata. Gases dissolve in the moist surface of the mesophyll cells. They then diffuse to the neighbouring cells. 1m Gases diffuse from the leaves to the environment in the reverse way.In woody stems, gas exchange takes place through the lenticels. 1m In roots, gas exchange takes place all over their surfaces. 1m Water and minerals:The water potential of the soil water is usually higher than that of the cytoplasm of the root hairs, water moves into the root hairs by osmosis. 1m Water passes across the cortex from cell to cell by osmosis or moves along the cell walls.1m Water is drawn up the xylem vessels by transpiration pull. 1m Most minerals are absorbed into the root cells by active transport. They are taken upagainst a concentration gradient using energy from respiration. 1m Some dissolved minerals are absorbed along water. 1m Communication max 3mReading to learn (p. 9-28)1Certain plants can make use of toxic substances as their nutrients. 1m 2It is cost-effective. 1m 3The toxic substances absorbed by the plants may escape from the leaves and pollute the air.The plants containing the toxic substances may affect the environment if they are notproperly disposed of.The clean-up process is slow because the plants take months to grow.(any 2) 1m x 2 4When the plants decay, the toxic substances absorbed by the plants may return to the soil.Animals living in soil may be harmed by the toxic substances. 1mChapter 10 Transpiration, transport and support in plants ExerciseMultiple-choice questions (p. 10-23)1 D2 C3 A4 C5 BShort questions (p. 10-24)6 HKCEE Biology 1997 I Q17 HKCEE Biology 2001 I Q38 HKCEE Biology 2006 I Q99 a Xylem cells have thick cell walls which contain a hard substance called lignin as wellas cellulose. This makes the xylem strong enough to provide support to the plants.2m The cortex cells have thin cell walls only. Support is provided by their turgidity.When the cells are turgid, they become rigid and press against each other. 2mb Diagram: The stem bends greatly and the leaves drooped 1mReason:The non-woody stem contains little xylem tissue. 1mIts support is mainly by the turgidity of cells. The cells become flaccid when there isnot enough water. 1mc The buoyancy of water provides much support to the submerged plant. 1m10 a i Water flow is not restricted. / Transpiration stream is maintained. 1mii Provides support / Waterproof to prevent water loss 1mb i The rate of water flow in xylem decreases as the total area of the stomatalopenings decreases. 1m ii Increasing temperature leads to higher rate of evaporation / transpiration. 1miii Lower plateau (start and finish at same point) 1m 11 HKCEE Biology 2002 I Q3Structured question (p. 10-26)12 a The dye had travelled 9 cm up the stem in two hours. 0.5mRate of water movement = 9/2 0.5m= 4.5 cm per hour 1mb Any two of the following: 1m x 2Increase the light intensity around the plant.Decrease the relative humidity around the plant.Use a fan to increase ventilation around the plant.c Prepare several Coleus plants with different numbers of leaves. 1mPut them under the same condition and start the experiment at the same time. 1mEstimate the total surface area of leaves in each plant by tracing all the leaves ongraph paper and counting the number of squares. 1mThe rate of water movement is expected to increase with the surface areaof leaves. 1mThe relationship may not be a directly proportional one since the surface areas ofstems are not included but transpiration occurs through the cuticle of stems as well.2m Essay (p. 10-27)13Light intensity:The rate of transpiration increases with an increase in light intensity. 1m As the light intensity increases, the stomata open wider. 1m More water vapour in the air space diffuses out through the stomata. 1m In darkness, the stomata close, so that the rate of transpiration decreases.1m Wind:The rate of transpiration increases in windy conditions. 1m In still air, the water vapour that diffuses out of the leaves accumulates around the stomata.1m Wind blows away the water vapour and prevents the decrease in the concentration gradient of water vapour between the air space in the leaves and the surrounding air. 1m Relative humidity:The rate of transpiration decreases with an increase in the relative humidity of thesurrounding air. 1m Since the air space in the leaves is saturated with water vapour, a higher relative humidity of the surrounding air will decrease the concentration gradient of water vapour between the air space and the surrounding air. 1m Therefore, less water vapour from the air space will diffuse out through the stomata. 1m (Or correct answers for other factors, e.g. air temperature, availability of soil water, air pollution, air pressure, etc.)14 HKALE Biology 2005 II Q5aReading to learn (p. 10-28)1Plants lose water rapidly under hot, dry conditions 1m when the stomata open for gas exchange. 1m The availability of water to plants is low. 1m2The needle shape greatly reduces the surface area of leaves. 1m Less water evaporates from the leaf surface. 1m3The needle-like leaves contain few chloroplasts. 0.5m The amount of food produced by photosynthesis in the leaves is small. 0.5m Instead, the epidermal cells of the stems contain many chloroplasts. 0.5m They can carry out photosynthesis to produce sufficient food for the plant.0.5m 4The swollen stems of cacti store a lot of water. 1m The turgidity of cells provides support for the plant. 1m。

英语文章

Renewable energyFreezing the sunA double blow for solar energyJun 26th 2008 | From The Economist print editionEPAIT SEEMED so promising—mirrors sprawled across desert land in the scorching south-west delivering clean electricity and helping to wean Americans off imported fossil fuels. Some scientists and industry developers claim that Nevada’s empty and sun-drenched expanses alone could supply enough terawatts to power the entire country.Now even the optimists fear this wonderful prospect may be a mirage. Congress has been dithering over extending a valuable investment tax credit for solar-energy projects, which solar advocates say is critical to the future of their industry but which is due to expire at the end of the year. The latest attempt failed in the Senate earlier this month: prospects for a deal before November’s presidential and congressional elections now look dim. Uncertainty has led some investors to delay or abandon projects in the past few months. Rhone Resch, the president of the Solar Energy Industries Association, said if the tax credits are allowed to expire at the end of the year, “it will result in the loss of billions of dollars in new investments in solar.”Further dampening hopes for a big solar-energy boom, the federal Bureau of Land Management (BLM) has abruptly slapped a moratorium on new applications to put solar collectors on federal land. The agency says it has a backlog of more than 130 applications and needs to conduct a region-wide environmental-impact study on the industry before it will accept any more. The study will take 22 months to complete, however. Few argue against trying to preserve precious water sources and protect desert tortoises and other creatures that might not enjoy cohabiting with sprawling fields of mirrors. But many solar advocates wonder why the government is not acting as cautiously when it comes to drilling for oil and gas.Senator Maria Cantwell, a Democrat from Washington state, wants a congressional probe into the proposed moratorium. “The fac t that the BLM pops this out without people even knowing about it, especially when solar thermal looks extremely promising as a baseload [power source], is not right,” she says. Harry Reid of Nevada, who is the majority leader in the Senate, also condemns the BLM’s freeze, saying that it could “slow new development to a crawl”.The BLM is not without its supporters, however. At a public meeting on June 23rd in Golden, Colorado, Alex Daue, of the Wilderness Society, said that his organisation supports renewable-energy development as long as it doesn’t damage other important resources. The message is clear: no rubber stamps, even for renewable energy.可再生能源冻结太阳使用太阳能的一个双重打击2008年6月26日|从经济学人印刷版EPAIT显得那么有前途，镜子趴在灼热的沙漠土地上，南方和西部地区提供清洁的电力帮助戒除美国人把进口矿物燃料。

2009 H.J. Hermens Motor Unit Properties in the Biceps Brachii of Chronic Stroke Patients Assessed

Motor Unit Properties in the Biceps Brachii of Chronic Stroke Patients Assessed with High-DensitySurface EMGL.A.C Kallenberg, PhD, H.J. Hermens, PhDRoessingh Research and Development,Enschede, the Netherlands,l.kallenberg@rrd.nlAbstract —Motor unit (MU) properties of the biceps brachii and Fugl-Meyer score were assessed in stroke patients and healthy controls during passive and active elbow flexion and extension contractions. The level of motor recovery as assessed with the Fugl-Meyer score was correlated with the ratio of the size of the motor unit action potentials (MUAPs) at the affected side and the unaffected side. This ratio may reflect the extent to which reinnervation has occurred on the affected side. The RMS value of the MUAPs recruited during the stretch phase of the passive contractions was lower than the RMS value of MUAPs recruited during active contractions. This may indicate that only smaller MUs are affected by increased sensitivity to muscle stretch while a larger part of the MU pool can be recruited voluntarily. Keywords-motor unit properties; stroke;high-density surface EMG; biceps brachii; elbow flexion and extensionI. I NTRODUCTIONAs a consequence of a stroke, motor control and motor unit (MU) characteristics may change. Spasticity may occur, control of MUs of the affected muscles may be lost (paresis), and voluntary motor control of remaining MUs may change. Many researchers have investigated muscle activation and coordination patterns after stroke. Weakness, abnormal co-contraction of antagonistic muscles, abnormal co-activation patterns, muscle fatigue and delays in initiation and termination of muscle activity have been reported [1-7]. However, knowledge about underlying changes in properties and control of motor units (MUs) after a stroke is still limited.In dynamic contractions, the often reported hyper-excitability of the stretch reflex (for review see [8]) plays an important role. The increased response to muscle stretch may amongst others be related to hyperexcitability of the α motor neuron pool or to an increased sensitivity of the muscle spindles (Ia and II afferents). However, it is unknown whether the complete MU pool or only part of it is affected.So far, MU characteristics after a stroke have been investigated using intramuscular EMG recordings. With a grid of small, closely spaced electrodes placed on the skin above the muscle of interest (Fig. 1), a 3-dimensional (2D-spatial and in time) picture of muscle activity can be obtained non-invasively: high-density surface EMG (HD-sEMG).Figure 1. 2D-electrode array that was used for the recordings (Helmholtz Institute, Aachen, Germany). The array was placed on the biceps brachii with the columns parallel to the line from the acromion to the cubital fossa.Because of the high spatial selectivity that can be obtained in this way, motor unit action potentials (MUAPs) can be distinguished and extracted, and their propagation along the muscle fibers can be tracked [9-12].The aim of this study was to investigate MU characteristics of the biceps brachii in post-stroke subjects with HD- sEMG.II.M ETHODSA. SubjectsTwenty healthy volunteers without known neuromuscular disorders were included in the study. Hemiparetic stroke patients with a first unilateral ischemic stroke and sufficient cognitive abilities to understand spoken instructions were recruited from rehabilitation center ‘Het Roessingh’. Subjects had to be at least six months post-stroke and had to be able to move their arm against gravity (Medical Research Council score for biceps brachii ≥ 3). Passive shoulder abduction to at least 70 degrees had to be possible without pain. Exclusion criteria were presence of additional orthopedic diseases of the upper extremities, psychiatric comorbidity, hypersensibility, shoulder-hand syndrome, and use of antispastic medication. Eighteen stroke patients participated in the study. All subjects signed an informed consent. The study was approved by the local medical ethics committee and experiments were performed in accordance with the Helsinki Declaration of 1975. Demographic characteristics of the population are reported in Table 1.ThB1.3Proceedings of the 4th InternationalIEEE EMBS Conference on Neural Engineering Antalya, Turkey, April 29 - May 2, 2009TABLE I. D EMOGRAPHIC CHARACTERISTICSControl groupPatient groupSex5 men, 15 women 12 men,6 women Age (years) 59 (46-71) 64 (39-78) Weight (kg) 72 (60-93) 80 (55-155) Height (cm)171 (159-193)176 (158-184)Body mass index (kg/m 2)24.4 (21.2-30.7) 25.7 (21.6-34.8)Time since stroke (years)n.a. 2 (0.5-10)Affected side n.a. 11 left, 7 right Fugl-Meyerscoren.a. 35.5 (9-62) Ashworth scoren.a.2 (0-4)Median values and ranges (jn brackets) are reported. N.a.: not applicableB. General proceduresIn the stroke patients, the Fugl-Meyer score for the upper extremity, a clinical scale for motor recovery, was assessed. Subsequently, the maximal voluntary contraction (MVC) of elbow flexion was determined at both sides. Static isometric step contractions (10 force levels from 5% to 50% MVC were performed with unaffected side followed by the same series of contractions for the affected side. Next, cyclic passive and active elbow flexion and extension movements were performed with the dominant side (healthy subjects) or the affected side (stroke patients). During passive movement, the experimenter supported the elbow and moved the arm throughout the range of motion at a fast speed (approximately 1.25 s per cycle). During active movement, subjects moved their arm at a self-selected comfortable speed (approximately 2 s per cycle) throughout the full range of motion. When a stroke patient was not able to move the arm the experimenter helped by supporting the elbow joint. Both active and passive movements were repeated ten times per trial, and three trials were performed.C. High-density sEMG measurementsHD-sEMG of the biceps brachii was recorded with a two dimensional 16-channel electrode array placed on the skin above the muscle (Fig. 1). The array consisted of four columns of gold-coated pin-electrodes with a diameter of 1.5 mm, the first and fourth containing three electrodes and the middle two containing five electrodes. The inter-electrode distance was 10 mm in both directions.Electrode placement was done in accordance with the SENIAM (Surface Electromyography for the Non-Invasive Assessment of Muscles) recommendations for surface EMG recordings [13]. The electrode array was placed on the biceps brachii with the columns parallel to the line from the acromion to the cubital fossa, with the center of the array placed one third of the distance from the cubital fossa.Figure 2. Example of high-density sEMG signals from the biceps brachii muscles of a stroke subject. Left: unaffected side, right: affected side. The contraction level was 20% of the maximum voluntary contraction force. Bipolar signals from one column of a 16-channel electrode array are shown. Signals were visually inspected online. Propagation of signals, absence of innervation zones and minimal shape differences between subsequent signals were used as criteria for correct placement and alignment of the electrode columns in parallel to the muscle fibres. If necessary, the electrode array was repositioned. In most subjects, a small amount of conducting gel was applied to the electrodes to improve the signal-to-noise ratio.D. Data analysisBipolar signals with an inter-electrode distance of 10 mm were constructed from the two middle columns of monopolarly recorded signals. This resulted in two sets of four unidirectionally propagating bipolar signals. The set with the best signal quality was manually selected for further processing. Motor unit action potentials (MUAPs) were extracted from the sEMG signals using an algorithm based on the Continuous Wavelet Transform. Variables describing the MUAPs were calculated for all detected MUAPs without classifying them to their corresponding MU. The RMS value (RMS MUAP ) and the median frequency of the power spectrum (FMED MUAP ) of each detected MUAP were calculated. Histograms of these variables were used to examine properties of the MU population. RMS MUAP , related to the size of the MU, was calculated by taking the square root of the sum of all squared data samples of the MUAP, divided by the number of samples. FMED MUAP reflects the frequency content of the MUAP, which is related to the MUAP duration [14] and muscle fiber conduction velocity [15-17] which in turn is related to the recruitment threshold of the MU [18]. FMED MUAP was calculated as the median value of the power spectrum, obtained using the fast Fourier-transform with a Hanning window. Ratios of FMED MUAP and RMS MUAP at the affected side divided by the unaffected side were assessed to quantify within-subject differences between the sides.For the static contractions, median values of the MUAP properties were calculated for each step. For the dynamic contractions, median values of the MUAP properties across the three trials were calculated for each subject.Figure 3. Scatter plot of the ratio of RMS MUAP on the affected side divided by RMS MUAP on the unaffected side against Fugl-Meyer score. Data from step7 (35% MVC). The explained variance is 50% (p<0.011).E.StatisticsTo investigate differences in EMG variables between sides, groups and movement type (active or passive), mixed linear models were applied. For the static contractions, the model included step (contraction level), side (affected or non-affected) and the interaction of step with side as fixed factors. The interaction between step and side was included to examine differences between the sides in response to an increasing force level. For the dynamic contractions, the model included movement type (passive or active movement), group, and the interaction of movement with group as fixed factors. The interaction between movement and group was included toexamine whether differences between the active and passive movements depended on the group.III.R ESULTSData of three subjects were of insufficient quality and were not used in the analysis.An example of a recording of EMG signals of the affected and unaffected side is shown in Figure 2. In this subject, the MUAPs were generally larger on the affected than on the unaffected side.In the static contractions, 7 out of 15 subjects showed larger RMS MUAP values at the affected side than at the unaffected side, 5 subjects showed smaller values and 3 subjects did not show differences. Interestingly, the median Fugl-Meyer score was considerably higher in the group with larger RMS MUAP values at the affected side (Fugl-Meyer score 42 versus 20 out of 66). The ratio of RMS MUAP of the affected side divided by that of the unaffected side correlated with the Fugl-Meyer score for the force levels from 15% to 45% (Spearman’s rho between 0.6 and 0.74, p<0.039), see Fig. 3.Figure 4. MUAP properties during active and passive contractions in both groups. + indicates outliers (values between 1.5 and 3 bar lengths from theupper edge of the bar).The results of the cyclic contractions are presented in Fig.4. The number of detected MUAPs was significantly larger during active than during passive movements (p<0.001), and there was a trend for a higher number of MUAPs in the stroke group than in the control group (p<0.07). RMS MUAP was higher in the stroke group (p<0.001) and in both groups it was higher during active movements than during passive movements (p<0.001). FMED MUAP was not different in both groups nor in both movement conditions.IV.D ISCUSSIONThe aim of the study was to investigate MU characteristics in post-stroke subjects.For the dynamic contractions larger MUAPs, as reflected in higher RMS MUAP values, were found in the stroke group compared to the control group. In the static contractions a correlation between a clinical scale, the Fugl-Meyer score, and the ratio of RMS MUAP at the affected divided by the unaffected side was found. Since RMS MUAP is related to MU size,RMS MUAP and RMS MUAP ratio might reflect the extent to which re-innervation, resulting in larger MUs, has occurred. Re-innervation is a compensation strategy for paresis and is therefore likely to be related to the functional capacity of the muscle, which may explain the correlation between RMS MUAP ratio and Fugl-Meyer score.For the dynamic contractions, the MUAPs during the stretch phase of the cycle were considerably smaller than the MUAPs recruited during the active movements. Several studies in cats [19-20] and in humans [21-23] have shown that recruitment of MUs during the stretch reflex follows the Henneman size principle. Apparently, the recruitment during the stretch reflex is limited to the smaller low-threshold MUs while a much larger part of the MU pool can be recruited voluntarily. This might mean that the hyperexcitability of the stretch reflex could be reduced when the activity of small MUs with small diameter motor neurons could selectively be suppressed by medication. Future research should aim at investigating if such an approach is feasible and clinically effective.R EFERENCES[1]Chae J, Yang G, Park BK, Labatia I. Muscle weakness andcocontraction in upper limb hemiparesis: relationship to motor impairment and physical disability. Neurorehabil Neural Repair 2002;16:241-8[2]Dewald JP, Pope PS, Given JD, Buchanan TS, Rymer WZ. Abnormalmuscle coactivation patterns during isometric torque generation at the elbow and shoulder in hemiparetic subjects. Brain 1995; 118(Pt 2):495-510[3]Hammond MC, Fitts SS, Kraft GH, Nutter PB, Trotter MJ, RobinsonLM. Co-contraction in the hemiparetic forearm: quantitative EMG evaluation. Arch Phys Med Rehabil 1988; 69:348-51[4]Toffola ED, Sparpaglione D, Pistorio A, Buonocore M. Myoelectricmanifestations of muscle changes in stroke patients. Arch Phys Med Rehabil 2001; 82:661-5[5]Hammond MC, Kraft GH, Fitts SS . Recruitment and termination ofelectromyographic activity in the hemiparetic forearm. Arch Phys Med Rehabil 1988; 69:106-10[6]Chae J, Yang G, Park BK, Labatia I. Delay in initiation and terminationof muscle contraction, motor impairment, and physical disability in upper limb hemiparesis. Muscle Nerve 2002; 25:568-75[7]Dewald JP, Beer RF, Given JD, McGuire JR, Rymer WZ.Reorganization of flexion reflexes in the upper extremity of hemiparetic subjects. Muscle Nerve 1999; 22:1209-21 [8]Voerman GE, Gregoric M, Hermens HJ. Neurophysiological methodsfor the assessment of spasticity: the Hoffmann reflex, the tendon reflex, and the stretch reflex. Disabil Rehabil 2005;27:33-68[9]Gazzoni M, Farina D, Merletti R. A new method for the extraction andclassification of single motor unit action potentials from surface EMG signals. J Neurosci Methods 2004;136:165-77[10]Merletti R, Farina D, Gazzoni M. The linear electrode array: a usefultool with many applications. J Electromyogr Kinesiol 2003;13:37-47 [11]Schulte E, Farina D, Rau G, Merletti R, Disselhorst-Klug C. Singlemotor unit analysis from spatially filtered surface electromyogram signals. Part 2: conduction velocity estimation. Med Biol Eng Comput 2003;41:338-45[12]Kallenberg LA, Hermens HJ. Motor unit action potential rate and motorunit action potential shape properties in subjects with work-related chronic pain. Eur J Appl Physiol 2006;96:203-8[13]Hermens HJ, Freriks B, Disselhorst-Klug C, Rau G. Development ofrecommendations for SEMG sensors and sensor placement procedures. J Electromyogr Kinesiol 2000;10:361-74[14]Hermens HJ, van Bruggen TAM, Baten CTM, Rutten WLC, BoomHBK. The median frequency of the surface EMG power spectrum in relation to motor unit firing and action potential properties. J Electromyogr Kinesiol 1992;2:15-25[15]Lindstrom LH , Magnusson RI. Interpretation of myoelectric powerspectra: a model and its applications. IEEE Trans Biomed Eng 1977;65:653-662[16]Dumitru D, King JC, Zwarts MJ. Determinants of motor unit actionpotential duration. Clin Neurophysiol 1999;110:1876-82[17]Arendt-Nielsen L, Mills KR. The relationship between mean powerfrequency of the EMG spectrum and muscle fibre conduction velocity.Electroencephalogr Clin Neurophysiol 1985;60:130-4[18]Andreassen S, Arendt-Nielsen L . Muscle fibre conduction velocity inmotor units of the human anterior tibial muscle: a new size principle parameter. J Physiol 1987;391:561-71[19]Prather JF, Clark BD, Cope TC. Firing rate modulation of motoneuronsactivated by cutaneous and muscle receptor afferents in the decerebrate cat. J Neurophysiol 2002;88:1867-79[20]Cope TC, Sokoloff AJ, Dacko SM, Huot R, Feingold E. Stability ofmotor-unit force thresholds in the decerebrate cat. J Neurophysiol 1997;78:3077-82[21]Bawa P, Binder MD, Ruenzel P, Henneman E. Recruitment order ofmotoneurons in stretch reflexes is highly correlated with their axonal conduction velocity. J Neurophysiol 1984;52:410-20[22]Calancie B, Bawa P. Recruitment order of motor units during the stretchreflex in man. Brain Res 1984;292:176-8[23]Calancie B, Bawa P. Voluntary and reflexive recruitment of flexor carpiradialis motor units in humans. J Neurophysiol 1985;53:1194-20。

讨论铁路对话英语作文

讨论铁路对话英语作文Title: The Impact of Railways: A Discussion。

Railways have played a pivotal role in shaping the modern world, revolutionizing transportation, commerce, and social interaction. In this essay, we delve into the multifaceted impact of railways and their significance in today's global context.First and foremost, railways have significantly enhanced connectivity and accessibility. They have bridged vast distances, connecting remote regions and urban centers, thereby facilitating the movement of goods and people. The efficiency and speed of rail transport have made it a preferred mode for long-distance travel and freight shipment. For instance, the transcontinental railways in countries like the United States and Canada have been instrumental in fostering economic growth and nationalunity by linking disparate regions.Moreover, railways have spurred economic developmentand industrialization. The construction of railways necessitates the utilization of various resources and labor, thereby stimulating economic activity. Furthermore,railways facilitate the transportation of raw materials and finished goods, enabling industries to expand their markets and increase productivity. The development of railway networks often leads to the emergence of new towns andcities along the routes, fueling urbanization and providing employment opportunities.Additionally, railways have had a profound impact on trade and globalization. By facilitating the movement of goods across vast distances, railways have contributed to the integration of national and international markets. They have enabled businesses to access distant markets more efficiently and cost-effectively, thereby fostering trade and economic exchange on a global scale. Furthermore, railways have played a crucial role in facilitating international trade by connecting inland regions to ports and facilitating the transportation of goods to export markets.Furthermore, railways have environmental benefits compared to other modes of transportation, such as road and air transport. Rail transport is generally more energy-efficient and produces fewer emissions per ton-mile than road transport, making it a more sustainable option for freight movement. Additionally, the electrification of railways and the adoption of cleaner technologies have further reduced their environmental footprint. As concerns about climate change and air pollution continue to grow, railways are increasingly viewed as a greener alternativeto other modes of transport.Moreover, railways have social implications, shaping patterns of mobility, accessibility, and social interaction. They have facilitated the movement of people for work, education, and leisure, thereby promoting socialintegration and cultural exchange. Furthermore, railways have democratized travel by making it more accessible to people of diverse socio-economic backgrounds. The affordability and accessibility of rail transport have made it a vital lifeline for many communities, particularly inrural and underserved areas.In conclusion, railways have had a profound and far-reaching impact on the world, transforming transportation, commerce, and society. From enhancing connectivity and economic development to fostering trade and globalization, railways continue to play a vital role in shaping the modern world. Moreover, their environmental benefits and social implications underscore their significance as a sustainable and inclusive mode of transport in today's globalized world. As we look to the future, railways are poised to remain a critical component of the global transportation infrastructure, driving economic growth, fostering sustainability, and promoting social inclusion.。

《罗克斯维尔火车站的猫》（节选二）

《罗克斯维尔火车站的猫》（节选二）作者：琼·克雷格黑德·乔治来源：《英语世界》2020年第09期A blade of grass twitched just outside the tire. Rachet instinctively drew her feet under her and studied the grass through the tear in the tire. It quivered—something alive. Her hunger told her—mouse. Her tail twitched， her rear end went up， her chest lowered， and she pounced， swinging an open-clawed paw—and missed.The mouse ran. It scurried down its trail and dove under a soda can. Rachet ran after it but only so far. Sitting down behind a clump of grass， she waited， motionless， for the mouse to come out and go home.The ground shook， and a train roared into the station. She remained still and listened. Moments later a man’s voice shouted “All aboard！” The mouse took advant age of the sound and scurried into its nest in the ground.With its disappearance Rachet felt really hungry. She sniffed. But she didn’t smell mouse. She smelled more cats crossing the vacant lot.Queenella was first. Well behind her， running short distances， then stopping， came Ice Bucket， a white but dirty cat. Next came Flea Market. Her brown fur was matted from biting fleas. A small calico， Elizabeth， came slinking low from the vacant lot. She crept daintily and shyly. Then came Tatters and Tachometer， sisters. They dashed out from under the old tollbooth at the entrance to the station parking lot， where they had made their First Home after the parking meters had been installed and the booth abandoned. All cats seek a First Home， the place to which they return again and again， be it a pillow by a fire， a corner of a couch， or a sheltered spot in the wilds. It is not necessarily a permanent place， for a cat will shift homes according to food supply， mood， and events. Sometimes one will change First Homes just for a cat whim.All the cats were walking to the railroad station. Their inner alarm clocks told them it was 6：45 A.M.—the time the Bent Lady put out cans of cat food by the station platform. She came there every day to feed the cats of Roxville Station. She liked them better than the people in the housing project，who rarely spoke to her. The cats liked her， too. They meowed and said hello by bumping their foreheads against her trousers.Rachet smelled the food—the kind of food from a can she had sometimes been fed. Its aroma piqued her hunger， and the hunger drove her forward. Boldly she joined the cats on the trek to the Bent Lady’s hand-out—stopping and starting to keep out of their sight. Near the station platform shesat down and watched Ice Bucket and Flea Market approach the food. Their tails were up， not quite as high and straight as Queenella’s， and they swished them to express their wariness of the queen.就在轮胎外面，有片草叶抖了抖。

关于对讲机的英语句子

关于对讲机的英语句子英文回答：What is a two-way radio?A two-way radio is a transceiver, a device that can both transmit and receive radio waves, allowing two or more people to communicate over a distance. Two-way radios are used in a wide variety of applications, including public safety, business, and personal use.How does a two-way radio work?Two-way radios work by converting sound waves into electrical signals, which are then transmitted over the airwaves. The receiver in the other radio converts the electrical signals back into sound waves, which can be heard by the user.What are the different types of two-way radios?There are two main types of two-way radios: simplex and duplex. Simplex radios can only transmit or receive at a time, while duplex radios can do both simultaneously. Duplex radios are typically used for more complex applications, such as public safety communications.What are the benefits of using a two-way radio?Two-way radios offer a number of benefits over other forms of communication, including:Reliability: Two-way radios are not reliant oncellular networks or the internet, so they can be used even in areas with poor or no coverage.Security: Two-way radios are secure, as they do not transmit conversations over the airwaves.Convenience: Two-way radios are easy to use and can be carried around with you.Cost-effective: Two-way radios are relatively inexpensive to purchase and operate.What are the applications of two-way radios?Two-way radios are used in a wide variety of applications, including:Public safety: Two-way radios are used by police officers, firefighters, and emergency medical personnel to communicate with each other and with dispatchers.Business: Two-way radios are used by businesses to communicate with employees in the field, such as delivery drivers, construction workers, and security guards.Personal use: Two-way radios are used by individuals for a variety of purposes, such as hunting, camping, and off-roading.中文回答：什么是对讲机？对讲机是一种收发两用机，它既可以发送无线电波，也可以接收无线电波，它允许两个人或更多人在一定距离内进行通信。

铁路英语试题及答案

铁路英语试题及答案一、选择题（每题2分，共20分）1. What does the abbreviation "CR" stand for in the context of railways?A. Central RailwayB. Cross RailwayC. China RailwayD. Coastal Railway2. Which of the following is NOT a type of railway vehicle?A. LocomotiveB. Freight carC. Passenger carD. Airplane3. What is the term used for the process of a train stopping at a station?A. DepartureB. ArrivalC. StopoverD. Termination4. The term "signal" in railway operations refers to:A. A railway employeeB. A device indicating the status of the trackC. A type of trainD. A station5. Which of the following is a safety measure on a train?A. Seat beltsB. Air conditioningC. Fire extinguisherD. Oxygen mask6. What does "DPT" stand for in railway schedules?A. Departure TimeB. Destination TimeC. Delayed Passenger TimeD. Daily Passenger Traffic7. The "up" line in a railway context usually refers to:A. The line going northB. The line towards a higher elevationC. The line used for express trainsD. The line used for freight trains8. Which of the following is a term used for a railway junction?A. CrossingB. StationC. SignalD. Interchange9. The term "shunting" in railway operations means:A. The act of moving trains around a yardB. The act of boarding a trainC. The act of repairing a trainD. The act of cleaning a train10. What does "ATO" stand for in the context of railway technology?A. Automatic Train OperationB. Advanced Train OrderC. Automated Train OrderD. Automatic Train Orchestration二、填空题（每空1分，共10分）11. The __________ is responsible for the movement of trains on the tracks.(Answer: Signaller)12. A train's __________ is the total weight it carries, including the weight of the train itself.(Answer: Gross Load)13. The __________ is the part of the train where passengers can sit or stand.(Answer: Carriage)14. The __________ is the maximum speed at which a train is allowed to travel on a particular section of track.(Answer: Speed Limit)15. The __________ is a device used to control the speed of a train.(Answer: Brake)16. The __________ is the process of coupling two or more railway vehicles together.(Answer: Coupling)17. A __________ is a railway vehicle used for transporting passengers.(Answer: Coach)18. The __________ is the distance between two consecutive railway tracks.(Answer: Gauge)19. The __________ is a railway vehicle used for carrying goods.(Answer: Wagon)20. The __________ is the point at which a train changes direction.(Answer: Turntable)三、简答题（每题5分，共20分）21. Explain the purpose of a railway signal system.(Answer: The purpose of a railway signal system is to ensure the safe and efficient movement of trains by providing information about the status of the track, such as whether it is clear or occupied, and to control train speeds.)22. What are the main components of a railway station?(Answer: The main components of a railway station include platforms, ticket counters, waiting areas, information boards, and sometimes amenities like shops and restaurants.)23. Describe the role of a train conductor.(Answer: A train conductor is responsible for the overalloperation of the train, including ensuring passenger safety, managing the train crew, handling ticket inspections, and coordinating with station staff and signallers.)24. What is the difference between a freight train and a passenger train?(Answer: A freight train is designed to transport goods and commodities, while a passenger train is designed to transport people. Freight trains typically consist of a locomotive and a series of freight cars, whereas passenger trains consist of a locomotive and a series of passenger carriages.)四、翻译题（每题5分，共20分）25. 请将下列句子从中文翻译成英文：“列车晚点是因为前方轨道发生了故障。

Subway and Light Rail

Subway and Light RailAs we know, both subway and light rail, as a form of electrification railway system, are the artery of city transportation. They occupy less land of construction, cost less energy per unit of transportation volume, and make less noise and pollution than common means of transport. Furthermore, in spite of their huge load, almost 10 times as big as road transportation, they are still safe, comfortable, convenient, and fast. But, there is also difference between subway and light rail.First of all, in speed, subway runs faster than light rail, at a speed of 30--60km/h. Light rail runs at 18--40km/h. Moreover, subway can take more passengers. The subway car has a big capacity, generally rated capacity of 310 people/car, and each column has 4 to 10 cars, so the highest passenger volume of peak hour for one-way is 30.000 to 60.000 people. However, light rail uses the medium load car, generally rated capacity of 202 people/car, and each column has 2 to 4 cars, so the highest passenger volume of peak hour for one-way is 10.000 to 30.000 people. In addition, subway and light rail have difference in the weight of axles and in size themselves. The axles of subway commonly weigh more than 13 tons, and subway is 2.8 to 3 meters wide. The axles of light rail weigh less than 13 tons, andlight rail is 2.3 to 2.6 meters wide. Finally, subway and light rail are different in requirements of the turning radius. The minimum turning radius of subway is not less than 300 meters, and it can be not less than 250 meters at difficult areas. However, the minimum turning radius of light rail is not less than 100 meters, and it can be not less than 50 meters at difficult areas.Both subway and light rail are very necessary for modern life. I believe with the development of technology, subway and light rail will gain more improvement, which will bring people more convenience.。

人教版小学英语五年级上册各单元测试题

Unit One My New Teachers一. 大声朗读，找出画线部分读音与前面所给单词画线部分相同的单词. (4分)（）1。

no A。

now B。

how C。

know( )2。

eraser A. lamp B. lady C. library( )3。

umbrella A。

fun B. computer C。

music（）4。

like A。

fish B。

kind C。

kid二. 接龙写单词。

(10分）Miss( ) →__ __ __ ___ ___(聪明) → __ __ __ __（高的）→ lady( ）→__ ____ __ __(年轻）→go →（老的）→doll（ ) →__ __ __ __(喜欢）→eight( ）—→__ __ __ __(瘦的)三。

将单词归类，写在横线上面.(12分)strict Canada short driver Australia strongUK teacher farmer China quiet principal人物特征描写:_______________________________________________国家:_______________________________________________________职业：_______________________________________________________ 四。

翻译短语. （8 分)1.short and strong___________ 2。

university student___________3。

又漂亮又活泼_____________4。

一位和蔼的老师_________________五。

选择填空。

（16分）( )1。

Who’s ___________math teacher?A。

you B。

your C. yours( ）2.What is ___________like？A. himB. he C。

铁路最理想轨距2

铁路最理想轨距2(中英文实用版)英文文档：The Ideal Rail Spacing of 2Railway tracks are the backbone of transportation systems, connecting cities, towns, and regions across the globe.The distance between the tracks, known as the gauge, plays a crucial role in the efficiency, capacity, and safety of the railway network.The ideal rail spacing, often referred to as the "standard gauge," is widely accepted as the most efficient and cost-effective option for railway operations.The standard gauge is typically 1435mm (4 feet 8.5 inches) wide and has been adopted by the majority of the world"s railways.This width has historical origins, as it was based on the width of the wheelbase of horse-drawn coaches in the early 19th century.Despite its arbitrary origin, the standard gauge has become the global standard due to its widespread use and the network effects it creates.The ideal rail spacing of 2 is a reference to the distance between the inner faces of the two rails, which is twice the width of the gauge.This distance allows for the safe passage of trains, the efficient transfer of power from the tracks to the train wheels, and the effective operation of signaling and safety systems.The standard gauge provides several advantages over othergauges.Firstly, it allows for the efficient movement of goods and passengers, as it maximizes the capacity of the railway network.Secondly, it facilitates the integration of different railway networks, as the standard gauge is widely used around the world.This integration is crucial for international shipping and trade, as it allows for the seamless movement of goods across stly, the standard gauge minimizes maintenance costs and simplifies track construction, as it is the most common gauge used by railway companies.In conclusion, the ideal rail spacing of 2, which corresponds to the standard gauge of 1435mm, is the most efficient and cost-effective option for railway operations.Its widespread adoption has led to the creation of a global railway network that connects people, businesses, and economies across the world.中文文档：理想铁路轨距2铁路轨道是交通系统的骨架，连接着全球各地的城市、城镇和地区。

初中英语原文火车铁轨

初中英语原文火车铁轨Trains Go Faster!火车更快！In the 1700s, many scientists worked on steam engines.在18世纪，许多科学家致力于蒸汽机的研究。

In the 1760s, a scientist in England found a way to put steam engines and wheels together.在18世纪60年代，一位英国的科学家找到了一种将蒸汽机与车轮连接在一起的方法。

Soon people had a new type of transportation: the steam train.很快，人们就有了一种新型的交通工具：蒸汽火车。

In 1804, the first train engine was born in England.在1804年，第一个火车引擎在英国诞生了。

It travelled only about fifteen kilometres in two hours.它在两个小时里只能行进大约15公里。

In 1825, the first passenger railway opened.在1825年，首个客运铁路开通了。

The Rocket was the most famous early engine.火箭是最出名的早期引擎。

During the 1830s, countries all over the world started to build railways.在19世纪30年代，全世界都开始修建铁路。

Fifty years later many countries had railways.五十年之后，许多国家都有了铁路。

People built many train stations to help passengers get on and off the trains easily.人们修建了许多火车站，帮助旅客们轻松上下车。

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

9. 双线扫面与编织
综述
双线扫面和编织仅可由矢量产生。

它们位于浮雕工具栏或在助手工具栏。

双线扫面
通过沿两条驱动曲线扫动一个或多个横截面矢量来产生浮雕。

如果选择了Z轴控
制矢量选项，则该矢量将控制沿驱动曲线扫面产生的浮雕的横截面的Z高度。

例
∙产生一个新模型，将浮雕的尺寸设置为25mm×25mm。

∙产生两条折线，和如下所示的椭圆。

垂直的矢量被镜像以对称，但这并不是使用该命令的前提条件。

有
尖锐的边，在浮雕上将会产生缝隙。

∙在浮雕工具栏选择双线扫面按钮。

该表格提示选择需要的矢量，两条驱动曲线必须有方
向，像箭头显示的那样，作为标识。

控制矢量也在表格中选择。

在横截面区域，可以选择横截面在驱动曲线间出现的位
置，也可以删除横截面。

该部分也控制浮雕上的两条扫线。

最后，是您已经很熟悉的ArtCAM组合方式选项。

重设选项将取消对所有矢量的选择。

∙选择左边的垂直矢量。

∙点击顶部驱动曲线 - 选择按钮。

∙选择右边垂直的矢量。

∙点击底部驱动曲线 - 选择按钮。

顶部驱动曲线已被标记为A，箭头显示了方向。

底部驱
动曲线被标记为B，也有箭头显示。

箭头也显示了浮雕的方向，在该例中，起点在顶部。

可以在表格中改变每条曲线的方向，以得到合适的方
向。

注：驱动曲线可以是任何形状，但必须是一个矢量。

∙选择弯曲的矢量。

弯曲的横截面标记为数字1，且数字1 出现在驱动曲线的
起始部分，表示截面开始的位置。

如果没有选择其它截面，该截面将在全部驱动曲线之间
使用。

∙打勾跨间扫面和按高度缩放。

∙选择增加并按下计算，然后关闭。

浮雕就产生了。

如果Z 高度增加，横截面
高度将按其宽度比例升高或降低。

例 2
∙重设浮雕并产生下面的矢量。

用这四个矢量产生一个新浮雕。

∙在浮雕工具栏选择双线扫面按钮。

∙选择较大的曲线矢量。

∙选择成角度的折线矢量。

∙点击底部驱动曲线–选择按钮。

为了保证箭头指向相同的方向，可能需
要反转驱动曲线的方向。

这个形状将从方框中的形状弯曲成一个
弧形。

∙选择开矩形矢量。

∙点击增加横截面 - 选择按钮。

∙选择开椭圆矢量。

∙点击增加横截面 - 选择按钮。

截面被标以数字，且显示了它们和矢
量的相对位置。

∙按下计算 (不关闭该页面)。

浮雕就显示出来，通过增加其它
横截面，可以近一步限定浮雕形
状。

∙从浮雕顶部菜单选择重设浮雕。

∙选择开椭圆矢量。

∙在该页中按下增加横截面。

增加了另一个横截面，横截面2的位
置沿着曲线移动了。

横截面2的位置可能不理想，它可以
被移动。

在两个横截面页一个新的横截面出现了。

选择叉号，可以删除横截面。

∙在横截面 2按下位置按钮。

∙点击鼠标，拖出一条直线表示截面2的位置。

这样就固定了横截面2的位置，移
动数字以表示直线结束的新位置。

∙按下计算然后关闭。

一个新浮雕就产生了。

例 3
∙重设浮雕，并产生下面的矢量。

这四个矢量将被用来产生一个新
浮雕，底部矢量为 Z 轴控制曲
线。

∙选择浮雕工具栏的双线扫面按钮。

∙选择顶部水平矢量。

∙点击顶部驱动曲线 - 选择按钮。

∙选择底部水平矢量。

∙点击底部驱动曲线 - 选择按钮。

∙选择最下面的曲线矢量。

∙点击Z轴控制矢量 - 选择按钮。

最下面的曲线被标注为Z。

注：Z轴控制曲线的起始点和
驱动曲线相同，表示将产生正
向Z浮雕。

确保曲线以相同的方式行进。

Z轴控制曲线只改变Z轴方向的浮雕。

曲线的实际长度并不重要，因为ArtCAM将按比例改变这个长度以适应驱动曲线，但是端点必须和Y 轴保持一致(水平直线)。

∙选择开椭圆矢量。

∙点击增加横截面 - 选择按钮。

∙按下计算然后关闭。

浮雕在Z方向上下起伏。

编织
使用编织向导，可以从一系列互相交迭的矢量和一个横截面产生编织浮雕。

例1
∙产生一个新模型，将浮雕尺寸设置为25mm×25mm。

∙产生三个矢量作为驱动曲线，一个小矢量作为横截面。

交迭的矢量将作为驱动曲线的中心线。

较小的矢量将作为编织的横截面，它必须是
开矢量，这个截面矢量是实际尺寸。

∙按下Shift键，选择驱动曲线矢量和横截面矢量。

被选中后，矢量变成粉色，出现一个方框，环绕着最外面的
矢量，表示它们都被选中。

∙选择编织向导按钮。

ArtCAM 在矢量互相交迭的位置产生编织。

矢量的方向决定哪个矢量在下面，哪个矢量
在上面。

交迭长度决定交叉点上面或下面的编织长
度，通常选择相对于横截面。

% 下跨深度和% 上跨高度决定编织横截面
高度在编织点下面或上面的百分比。

拐角形状可以是圆形或方形，浮雕以相同的
方式组合。

∙保持选项为现有状态，点击接受。

ArtCAM即产生交迭：
例2
∙产生下面的矢量，包括这个小的半椭圆横截面矢量。

如果这个横截面太大，交迭矢量将穿过
自己本身。

∙选择编织向导按钮。

∙选择相对于横截面为1.5，设置为方形，然后点击接受。

选择了拐角形状为方形，编织就有了尖
锐的边，而不是平滑的边。

练习：编织形状
∙产生一个高度为 100，宽度为100，分辨率为800 x 800 像素，原点在中心的新模型。

∙显示网格，网格间距为2mm。

∙在0位置产生一条垂直参考线。

∙在0位置产生一条水平参考线。

∙在右手边的顶部产生下图所示的矢量。

由于这个编织形状是具有尖角，因此
选用长方形产生编织。

产生了一个形状后，可以使用组合镜
像命令复制编织形状。

∙选择方形矢量，然后选择小矢
量。

∙选择编织向导按钮。

∙填写显示的值，按下接受。

编织形状就产生了，且被镜像到其它边。

∙选择浮雕镜像合并。

∙选择顶部到底部然后关闭。

浮雕就完成了。

练习：水果盘
∙打开模型fruits-on-plate.art。

使用双线扫面，将这些矢量变为平面浮雕。

∙选择圆形菠萝矢量，然后产生一个角度为+45，开始高度为0.4，无剪裁的相加浮雕。

∙选择菱形矢量，产生相加的棱柱形浮雕，角度为+25，开始高度为0，无剪裁。

生成的浮雕超出了菠萝的边界。

为了删除
多余的浮雕，使用重设为零选项。

∙双击圆形菠萝矢量，选择重设为零。

∙用左边中间的叶子产生一个相加的穹形浮雕，角度为+45，开始高度为0.1，无剪裁。

∙用右边中间的叶子产生一个最高拼合的穹形浮雕，角度为+45，开始高度为
0.2，无剪裁。

∙用外面的叶子产生一个最高拼合的穹形浮雕，角度为+45，开始高度为0.4，按高度剪裁的高度设置为1mm。

∙选择香蕉的三个矢量，产生一个相加的双线扫面浮雕。

∙用这条线作为驱动曲线产生挤出浮雕，弧形作为开始截面轮廓，折线作为端部截面轮廓，然后最高拼合。

∙选择梨形并产生一个相加的滚动浮雕。

∙选择小棍矢量，产生一个最高拼合的滚动浮雕。

∙选择叶子矢量和截面产生一个最高拼合的双线扫面浮雕。

∙选择折线矢量相加一个旋转浮雕。

∙选择成组的锁链和附近的小矢量。

∙相加一个编织浮雕，键入下面的值，选择接受。

选择文字fruit，产生一个相加的棱锥形浮雕，无剪裁，开始高度为0，角度为+60度。