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Simulation of Acoustic Black Hole in a Laval Nozzle Hironobu Furuhashi ?and Yasusada Nambu ?Department of Physics,Graduate School of Science,Nagoya University,Nagoya 464-8602,Japan Hiromi Saida ?Department of Physics,Daido Institute of Technology,Nagoya 457-8530,Japan (Dated:March 24,2006)Abstract A numerical simulation of ?uid ?ows in a Laval nozzle is performed to observe the formation of an acoustic black hole and the classical counterpart to Hawking radiation under a realistic setting of the laboratory experiment.We aim to construct a practical procedure of the data analysis to extract the classical counterpart to Hawking radiation from experimental data.Following our procedure,we determine the surface gravity of the acoustic black hole from obtained numerical data.Some noteworthy points in analyzing the experimental data are clari?ed through our numerical simulation.PACS numbers:04.70.-s Keywords:Hawking radiation,Sonic analogue,Acoustic black hole,Laval nozzle,Classical counterpart
I.INTRODUCTION
The existence of the black hole horizon is essential to the Hawking radiation[1,2,3,4]. The horizon causes an extremely large redshift on an outgoing wave of a matter?eld during propagating from a vicinity of the horizon to the asymptotically?at region.This redshift results in the Planckian distribution of quantum mechanically created particles at the future null in?nity.Although the Hawking radiation has not yet been con?rmed observationally, it has been pointed out that the similar phenomenon appears on phonons in a transonic ?ow of a?uid.This theoretical phenomenon in the?uid is called the sonic analogue of Hawking radiation,and the transonic?uid?ow on which the sonic analogue of Hawking radiation occurs is called the acoustic black hole[5,6,7,8,9,10,11,12].In the transonic ?ow,the boundary between a subsonic and a supersonic region is the sonic point.The sonic point corresponds to the black hole horizon and called the sonic horizon.The region apart form the sonic point in the subsonic region corresponds to the asymptotically?at region in a black hole spacetime.The sound wave which propagates from a vicinity of the sonic point to the subsonic region receives the extremely large redshift and the sonic analogue of Hawking radiation appears on phonons.The Hawking temperature T H of the acoustic black hole is given by the gradient of the?uid velocity at the sonic point x=x s[5]:
T H= c
s dx v
counterpart to Hawking radiation.A candidate for the classical counterpart has already been introduced in the references[13,14]by using a Fourier component of an outgoing wave from a vicinity of the horizon.
By the way,since a realistic?uid is composed of molecules,the e?ect of the molecule size discrepancy of the?uid becomes one of the important issues of the acoustic black hole.This e?ect appears in the modi?ed dispersion relation at high energies of phonons.However,in the expansion by the molecule size discrepancy,the zeroth order form of the quantum ex-pectation value of the number operator 0|N|0 of phonons results in the thermal spectrum at least not so high energy region.That is,the e?ect of the molecule size discrepancy is not dominant in the sonic analogue of Hawking radiation.Therefore,before proceeding to the issue of the molecule size discrepancy,it is necessary to detect the ordinary Hawking radiation(thermal spectrum)by a real experiment in laboratory,and the molecule size dis-crepancy is not in the scope of this paper.Hence we concentrate on the construction of the practical procedure to extract the evidence of the Hawking radiation(thermal spectrum) from the experimental data.To do so,we make use of the classical counterpart to Hawking radiation.
We should emphasize here that the Hawking temperature(1)includes the Planck constant and we can not consider the temperature T
H
in discussing the“classical”counterpart to Hawking radiation.However we can consider the surface gravityκof the black hole horizon which is a purely classical quantity and relates to the Hawking temperature as k B T H= κ/2π.Hence,for the acoustic black hole,we consider the surface gravityκH of the sonic horizon instead of the Hawking temperature,
κH=c s d
c s
x=x s.(2)
In this paper,we aim to construct a practical procedure of the data analysis to obtain the classical counterpart to Hawking radiation in a realistic setting of the acoustic black hole.To do so,we perform a numerical simulation of a?uid?ow in a practical experimental setting,and demonstrate that our procedure works well to detect the classical counterpart to Hawking radiation.
We organize the paper as follows.In the section II,we review the acoustic black hole in a Laval nozzle and de?ne the classical counterpart to Hawking radiation.The section III is devoted to the introduction of our numerical method to simulate a transonic?ow,and
to the construction of the practical procedure of the data analysis.In the section IV,our numerical results are presented and we determine the surface gravity of the sonic horizon. Finally the summary and conclusion are in the section V.
II.ACOUSTIC BLACK HOLE WITH A LA V AL NOZZLE
We consider an acoustic black hole with a?uid in a Laval nozzle as proposed in[14].The Laval nozzle,as shown in the right panel in FIG.1,has a throat where the cross section of the nozzle becomes minimum.The?uid is accelerated from the up stream to the down stream and the?ow has the sonic point at the throat when a su?ciently large velocity is given at the inlet of the nozzle.Even if we prepare an initial?ow which has no sonic point (e.g.the lower part of the right panel in FIG.1),the?ow can settle down to a stationary transonic?ow(e.g.the upper part of the right panel in FIG.1)with appropriate boundary conditions at the inlet and the outlet of the nozzle.This is the sonic analogue model which corresponds to the gravitational collapse.
Here we note that,if a stationary transonic?ow is prepared from the beginning(which corresponds to the eternal black hole),we can not expect to obtain the classical counterpart to the Hawking radiation;for the eternal case,the tunneling of phonons across the sonic point can result in the Hawking radiation and this is the purely quantum e?ect.Hence, when we are interested in the“classical”counterpart to Hawking radiation,it is necessary to consider the situation of the sonic point formation in course of the dynamical evolution of the?uid?ow.As seen below,the sound wave which is prepared on the?uid?ow before the formation of the sonic point becomes the classical counterpart to the quantum?uctuation which causes the classical counterpart to Hawking radiation.
dρ∝ργ?1.(4) For a stationary background?ow,we can obtain the sound velocity c s and the cross section S of the nozzle as a function of the Mach number M=v/c s of the?ow:
c s=c in M2+2M2in+2M M2+2M2in+22(γ?1),(5)
where quantities with subscript “in”represent the values at the inlet of the nozzle.The spatial derivative of the Mach number at the sonic point x =x s is
dM (γ+1)
S d 2S
dx x =0=± 5
π,c s |x =0=(3|M ?|)1/6,(7)and the surface gravity given by Eq.
(2)is κH 2π 5π≈0.355.(8)
Here it should be emphasized that,because the cross section of the nozzle is set S (x )=2?cos(πx )with ?1 (8)with the surface gravity of the sonic horizon which is obtained through the observation of the classical counterpart to Hawking radiation in our numerical simulation. FIG.2:Absolute value of the Mach number as a function of a spatial coordinate x.Each line represents the stationary solution of the?ow with di?erent boundary value M in.The blue lines represent transonic?ows. B.Classical counterpart to Hawking radiation As originally shown in the reference[5],the perturbation of the velocity potential for the transonic?uid?ow obeys the same equation as a massless free scalar?eld in a black hole spacetime.Therefore the classical counterpart to Hawking radiation of the acoustic black hole in the Laval nozzle should be observed by the sound wave on the transonic?uid ?ow.The most important sound wave is the one which starts to propagate against the stream from the outlet of the nozzle before the formation of the sonic point(the lower part of the right panel in FIG.1)and passes through the throat just before the moment of the sonic point formation to reach the inlet of the nozzle(the upper part of the right panel in FIG.1).This sound wave receives the extremely large redshift which will cause the classical counterpart to Hawking radiation. When the?uid?ow is irrotational and we introduce the velocity potentialΦwhich relates with the?uid velocity as v=?xΦ,the evolution equation of the perturbationφofΦis obtained from Eqs.(3), 1 c2s [?t+v?x]φ?1 This corresponds to the Klein-Gordon equation φ=0with the acoustic metric ds2= Sρ c s+v ,w=t+ dx c′s0+v′0exp[?(c′s0+v′0)u],W= 1 c s (c2s?v2)exp ?2(c′s0+v′0) c s dx F ?UWφ=0.(14) The form of this metric near the sonic horizon is ds2≈?2S0ρ0(c′s0+v′0)dU dW,where c2s?v2≈2c s0(c′s0+v′0)x is used.This denotes explicitly that the coordinate(U,W)does not have coordinate singularities and corresponds to the Kruskal-Szekeres coordinate of the Schwarzschild spacetime.Here it should be recalled that,in the spacetime of the gravita-tional collapse(the left panel in FIG.1),the Kruskal-Szekeres coordinate is appropriate to describe the rest observer at the spacetime region before the formation of the black hole[2]. Hence the outgoing normal mode of the sound wave which corresponds to the zero point ?uctuation of the quantized matter?eld before the formation of the black hole(i.e.the mode function on the?at spacetime)is given by φin(U)=Aφe?iω0U,(15) whereω0is the initial frequency and Aφis the amplitude of this mode.In the original coordinate(t,x),this mode behaves as φin(U(u))=φin(t,x)=Aφexp iω0c s+v .(16) This yields the temporal wave form at the observation point x=x obs in the asymptotic region: φout(t)≡φin(t,x obs)=Aφexp iω0c s+v .(17) Fourier component of this mode is de?ned by φoutω= ∞?∞dtφout(t)e iωt,(18) and the power spectrum is P(ω)= φoutω 2= A2φeω/ωH?1(?∞<ω<+∞),(19) where the quantityωH is de?ned by ωH≡κH2πd c s 0.(20) Here it should be noted that,because the existence of the sonic point is assumed in the above discussion,the form of P(ω)of Eq.(19)must be obtained after the formation of the sonic horizon in the?uid?ow. One may think it is strange that the initial frequencyω0does not appear in the power spectrum(19).It is the fact that the initial frequencyω0does appear in the power spectrum in the context of the quantum?eld theory,because the amplitude Aφis determined by the normalization condition for the mode functions to be Aφ∝1/√ the thermal distribution of the power spectrum for the sound wave of a su?ciently large amplitude in practical experiments. As long as concerning one dimensional?uid?ow,the amplitude of the sound wave does not decrease during propagating from the outlet to the inlet of the nozzle.The one dimensional transonic?uid?ow corresponds to the two dimensional black hole spacetime in which no curvature scattering occurs.The theoretically expected power(19)is equivalent to the formula of the Hawking radiation for black holes derived ignoring the curvature scattering. Our purpose is to observe this thermal spectrum via the numerical simulation of a tran-sonic?ow in the Laval nozzle,and to construct the practical procedure of the data analysis. Because the observable sound wave is a real valued one,we prepare the following real valued input mode at the outlet of the nozzle before the formation of the sonic horizon: 1 φin(θ)(t)=Aφcos(ω0t+θ)= 2 e?iθφin(U(t,x))+e iθφin?(U(t,x)) .(22) The e?ect of the redshift due to the formation of the acoustic black hole gradually appears on the observed sound wave.The temporal evolution of the observed sound wave is a?ected by the formation of the acoustic black hole.That is,the information of the classical counterpart to Hawking radiation is encoded in the observed sound wave.Therefore,using the output form(17),the resulting output signal after the formation of the sonic horizon is given by 1 φout(θ)(t)= 2 e?iθφoutω+e iθφout?ω .(24) ,we can not obtain the pure Fourier Hence,because the initial phaseθappears inφout(θ) ω componentφoutωby observing once the real valued output signalφout(θ)(t).In order to retrieve the pure Fourier componentφoutωfrom the mixed Fourier componentφout(θ) ,we have ω to superpose two output modesφout(θ)andφout(θ+π/2),and obtain φoutω=e iθ φout(θ)ω+iφout(θ+π/2)ω .(25) It is obvious that the power spectrum of this Fourier component gives the same form as Eq.(19).Therefore,in order to obtain the Planckian distribution in the power spectrum P(ω)of the observed sound wave from real valued input signals,we have to combine at least two output modes of which the input phases di?er byπ/2. III.NUMERICAL SIMULATION OF TRANSONIC FLOWS IN A LA V AL NOZ-ZLE Our numerical simulation is designed to generate a one dimensional transonic?uid?ow from the initial con?guration with no sonic point.We prepare the input signal at the outlet of the nozzle and observe the sound wave at the inlet of the nozzle.At the same time,the practical procedure of the data analysis is constructed. A.Basic equations for numerical simulations For the numerical calculation,we rewrite the?uid Eqs.(3)using c s and v, 2 v?x c s+c s?x v+ ?x S γ?1 c s?x c s=0.(26b) γ?1 This set of equations is not suitable for a numerical simulation of wave propagation in a transonic?ow.We transform these equations to the advection form.We introduce the Riemann invariants J±(t,x)as follows J±≡v±2c s 8 ?x S 8 ?x S where V+=c s+v=γ+1 4 J?,V?=c s?v=γ?34J?.(29) The left hand side of Eqs.(28)are of the advection form.That is,if?x S=0and?t V±=0, J+propagates upward along t? dx/V+=const.and J?propagates downward along t+ dx/V?=const.This form of the equations is suitable to treat the propagation of waves numerically. In the sonic analogue of Hawking radiation,the perturbation of the velocity potential (sound wave)corresponds to the scalar?eld in a black hole spacetime as shown by Eq.(9). Therefore,in a practical experiment of an acoustic black hole,we should calculate the velocity potential by integrating the observed velocity of the?uid: Φ(t,x obs)≡ x obs x0dx v(t,x),(30) where x obs is the observation point of sound waves and x0de?nes the origin of the velocity potential.However,since our experimental setting is designed to observe the sound wave at a?xed spatial point x=x obs,the observational data is a temporal sequence of v(t,x obs)and we must devise the other method to obtain the velocity potential at the observation point. In the upstream subsonic region of the transonic?ow where the e?ects of the sonic horizon is negligible and the?ow is stationary,the sound wave propagates along the“null”direction as indicated by Eq.(11) t? x We make the?uid?ow against x-axis and assume v<0.The inlet of the nozzle is at x=1, the throat at x=0and the outlet at x=?1.The input wave is prepared at the outlet of the nozzle and the wave propagates against the?ow from x=?1to x=1.After the =0at the inlet,the set of ?ow settles down to a stationary transonic?ow,since?x S| x=1 =0at the inlet.This means that the inlet of the nozzle corresponds Eqs.(28)gives?x v| x=1 to the asymptotically?at region in the gravitational collapse spacetime.Hence we make the observation of the sound wave at the inlet and set x obs=1. We prepare a?ow with a homogeneous velocity distribution as the initial con?guration, v(0,x)=V i=const.<0,c s(0,x)=1.(34) This initial con?guration of?ow has no sonic point and corresponds to the?at spacetime region before the formation of a black hole.Since our evolution equations(28)are of the advection form,it is enough to set the boundary conditions for J+at the outlet and J?at the inlet: J+(t,?1)=J+(0,?1)+A J cos(ω0t+θ),J?(t,1)=J?(0,1)(35) where A J is a constant that represents the amplitude of the perturbation of J+at x=?1, and the values J+(0,?1)and J?(0,1)are determined consistent with Eq.(27)and Eq.(34). These boundary conditions mean that sound waves of constant amplitude continue to emerge from the outlet toward the inlet of the nozzle all the time of the numerical simulation.Here recall that the perturbationφof the velocity potentialΦplays the role of the scalar?eld in the ordinary Hawking radiation.The second term in J+(t,?1)at the outlet A J cos(ω0t+θ) causes perturbations of the velocity potential and results in the classical counterpart of Hawking radiation at the inlet of the nozzle.Because the amplitude of the sound wave in one dimensional?uid?ow does not decrease,the amplitude of the input mode of the velocity potential(21)is given by Aφ= c s1+v1 with di?erent initial phases θ1=?π/2,θ2=0and θ3=π/2.If the amplitude A J of the perturbation part of J +is small enough,then the backreaction e?ects in the velocity potentials Φout(θi )(i =1,2,3)at the observation point (x =1)are negligible and we can subtract the common background contribution by taking the di?erence among them.Hence we obtain the Fourier components of the perturbation (sound wave)at the observation point as follows φout(12)ω≡Φout(θ1)ω?Φout(θ2)ω=φout(θ1)ω?φout(θ2)ω ,(37a)φout(23)ω≡Φout(θ2)ω?Φout(θ3)ω=φout(θ2)ω?φout(θ3)ω,(37b) where Φout(θi )ωis the Fourier component of Φout(θi ).These Fourier components correspond to the real valued output signal of Eq.(24).Here we note that,according to the boundary condition (35),the perturbation parts of J +which produce the output signals of Eqs.(37)are given by δJ (12)+=√4 , δJ (23)+=√4 ,(38) where we used cos(ω0t )?cos(ω0t ±π/2)= √2 φout(23)ω +iφout(12)ω 2,(39) where the factor 1/2is introduced to eliminate the factor √2A J of the input signals (38).When we carry out a realistic experiment of the acoustic black hole,the power spectrum (39)gives the classical counterpart to Hawking radiation and it has to be compared with the theoretical form (19).Hence,it is recognized that we have to perform at least three independent experiments with three di?erent input phases and observe three independent output signals to obtain the classical counterpart to Hawking radiation. With our setting of the ?uid ?ow in the Laval nozzle,we carry out the numerical simu-lation by the ?nite di?erence method.We use the Cubic-Interpolated Pseudoparticle (CIP)method [15]for the interpolation between neighboring spatial mesh points.This method enables us to treat the shock which appears after the formation of the sonic point.We note here that the shock arises in the supersonic region and it does not a?ect the subsonic region where we observe the output signal.The procedure of the numerical simulation to observe the thermal power spectrum (19)of the perturbation of the velocity potential is as follows:Step 1:Generate the transonic ?uid ?ow three times with three di?erent initial phase values,θ1=?π/2,θ2=0and θ3=π/2.Then,using Eq.(32),obtain the full velocity potentials Φout(θi )(i =1,2,3). Step 2:Calculate the quantities φout(12)≡Φout(θ1)?Φout(θ2)and φout(23)≡Φout(θ2)?Φout(θ3). Then compute the Fourier components of them,φout(12)ωand φout(23)ω. Step 3:Calculate the power spectrum P obs (ω)=1 2?ω0A J 21e ω/ωH ?1,ωH ≡κH 2π v c s +v ,(42)and the e?ective frequency of the wave at x =1is given by ?ω0=ω0 1??c s +v .(43)The second term in Eq.(43)gives a negative contribution in our non-stationary setting of numerical experiment and the observed frequency ?ω0at x =1becomes smaller than ω0.The theoretically expected form of the power spectrum in our setting should be given by replacing ω0to ?ω0in the formula (19). IV.NUMERICAL RESULTS We use the parametersγ=7/5,A J=1.0×10?6andω0=100.The number of spatial mesh points are10001and the size of one mesh becomes?x=2/10001.The size of one temporal step is set?t=?x/10,and we calculate900000steps in time.The numerical simulation runs in the temporal range t=0～18.The spatial scale is normalized by L/2, where L is the length of the nozzle.The temporal scale is normalized by L/2c s(t=0),where we set c s(t=0)=1as denoted by the initial condition(34). A.no black hole case For the initial?uid velocity V i=?0.19,we do not observe the formation of an acoustic black hole.Figure3shows the evolution of the Mach number.After t～10,the Mach number at x=0reaches a constant value and a stationary?ow is realized. 1For FIG.6,7,13and14,we used the smaller value of the perturbation frequenctyω0=20to visualize where v(i)denotes the?uid velocity with the input phaseθi.We can see that the sound wave propagates from x=?1to x=1.Around the throat x=0,the?uid velocity has larger value compared to the other region and the phase velocity of the outgoing wave becomes smaller.Thus the slope of the constant phase line becomes larger around the throat. FIG.6:Spacetime distribution of˙v for V i=?0.19with A J=0,ω0=20.Colors are assigned according to the value of log|˙v|. FIG.7:Spacetime distribution of the velocity perturbationδv≡v(2)?v(1)for V i=?0.19with A J=0,ω0=20.Colors are assigned according to the value of log|δv|. Figure8shows the perturbation of the velocity potential at x=1.We set t0=3 in Eq.(32)to obtain the velocity potential.The observed perturbation of the velocity potential oscillates with a constant amplitude. FIG.8:The temporal evolution of the velocity potentialφout(12)andφout(23). 全国2013年10月高等教育自学考试 高级英语试题 课程代码：00600 请考生按规定用笔将所有试题的答案涂、写在答题纸上。 选择题部分 注意事项： 1．答题前，考生务必将自己的考试课程名称、姓名、准考证号用黑色字迹的签字笔或钢笔填写在答题纸规定的位置上。 2．每小题选出答案后，用2B铅笔把答题纸上对应题目的答案标号涂黑。如需改动，用橡皮擦干净后，再选涂其他答案标号。不能答在试题卷上。 I. Each of the following sentences is given four choices of words or expressions. Choose the right one to complete the sentence and blacken the corresponding letter on your Answer Sheet. (15 points, 1 point for each) 1．Dorothy accepted the news of war with ______ and sadness. A． excitement B． commitment C． bewilderment D． embarrassment 2． The government could face defeat if it tries to push through the ______ proposals. A． doubtful B． conspicuous C． questionable D． controversial 3． This single market is designed to ______ barriers to the free movement of goods, services and people. A． terminate B． abolish C． eliminate D． exclude 4． He has emerged from being a(n) ______ and unsure candidate into a fluent debater. A． hesitant B． indifferent C． pleasant D． considerate 5．Large paintings can ______ the feeling of space in small rooms. A． endear B． enhance C． enlarge D． encourage 2000年10月高级英语试题及答案 课程代码：0600 本试题分两部分，第一部分考核课程内容，1页至4页；选择题42分，非选择题18分。 第二部分考核水平，4页至8页；选择题20分，非选择题20分。本试题共8页，满分100分。考试时间150分钟。全部题目用英语作答（英语汉题目除外），并将答案写在答题纸的相应位置上，否则不记分。 Part One 1.The following paragraphs are taken from the textbooks, followed by a list of words or expressions marked A to X. Choose the one that best completes each of the sentences and write the corresponding letter on your answer sheet. One word or expression for each blank only. (0.5 point each, 12 points) . Programmers live in (1) fear of losing anyone's attention -anyone's. The (2) way to avoid doing so is to (3) everything brief, not to (4) the attention of anyone but instead to provide constant (5) through variety, novelty, action and (6). .But before he ever begins to write he will have (7) an emotional attitude from which he will never completely (8). It is his job, no doubt, to (9) his temperament and (10) getting stuck at some (11) stage, or in some (12) mood. .His car needs mechanics, and mechanics grow more expensive and less (13). The gadgets in the home are cheaper to (14) than repair. The more efficiently (15) the home seems to be, the more dependent it is on the great (16) corporations, as well as a diminishing army of servitors. Skills at the lowest level have to be (17) slavishly and exorbitantly (18). .It is only lately that I have (19) how much science of genetics is (20). Agronomists have taken to (21) all sorts of vegetables and fruits (22) their original nature. This sounds wonderful and often is insane. For the scientists have not as a rule (23) any interest whatsoever in the taste of the things they have (24) with! A.acquired B.avoid C.breeding D.changing E.constant F.discipline G.efficient H.escape I.found J.impersonal K.involved L.keep M.movement N.perverse O.premature P.replace Q.rewarded R.self-contained S.stimulation T.strain U.surest V.taken W.tempered X.wooed II. There are 15 sentences with a blank in each, followed by a list of words or expressions marked A to X. Choose the one that best completes each of the sentences and write the corresponding letter on your answer sheet. One word or expression for each blank only. (1 point each, 15 points) 25.In a hot summer day you would find the village children () in the small pond behind the woods. 26. I don't like the dishes in some Chinese restaurants abroad; for they () the local taste too much and the result is that the food is neither Chinese nor foreign. 27.Two pupils from the "Hope Schools" were () to represent Chinese children in the Euro 2000 ceremonies. 28. I think there is too much ( ) made by all people concerned, the parents, the media, and the authorities, about the university entrance examinations. 29. Suddenly the lights went out. She () in the dark for the matches. 30.He was very sad because he had tried very hard in the last three years but ()very little. #include 绍兴文理学院元培学院学年学期 英语专业____级《高级英语（上）》试卷（D） I. Matching (10%) Directions: Match the phrases in Column A with the appropriate Chinese explanations in Column B. Write down the letters with corresponding numbers on your ANSWER SHEET. Column A Column B 1 attribute to A 实行，实现，使生效 2 fall into B 一事无成，无进展 3 put … into effect C 恰当的例子 4 meddle in D 插手，干涉 5 pass for E 归因于 6 a case in point F 落入，陷入，分为 7 get nowhere G 误认为 8 in proper perspective H 强加于 9 let down I 用恰当的观点 10 impose on J 放下，降低，使失望 II. Paraphrase (20%) Directions: Explain in English the meaning of the underlined words or expressions in each of the following sentences and then write your answers on your ANSWER SHEET. 11. Unfortunately, acceptance, the imprecise response packing the least educational punch, gets the most equitable sex distribution in classrooms. 12. Classroom chivalry is not only misplaced; it is detrimental. 13. In a railroad accident a menagerie-tiger, whose cage had broken open, is said to have emerged, but presently crept back again. 14. A practical joker saw a discharged veteran carrying home his dinner. 15. The tiger is said to have emerged, but presently crept back again, as if too much bewildered by his new responsibilities. 16. The relationship is a formal and formalized one for which conventionalities suffice. 17. The construction of our vehicle presupposes a design. 18. This confident attitude, so essential to development of future speaking skill, is very fragile and can be stifled quite early. 19. The lion’s share of the damage is man’s doing. 20. I can guess that you are living on a devastated Earth. 21. Government is supposed to be the way we human beings handle our collective affairs, but we just can’t seem to get the hang of it. 22. As a model of lucid scrutiny of a life’s experience, Maugham’s The Summing-Up is unsurpassed. 23. I have never had to put wet towels round an aching brain in order to excavate the meanings from a poem of Tennyson. 24. Religious groups and those who elevate the status of poverty as they equate money with evil exhort us to live simply. 25. Some, on the other hand, determine to break out of their fettered status and relentlessly strive for their share of the gold. 26. Many fine business ideas go down the drain in this way. 27. They develop skills, become knowledgeable, develop expertise, and work very hard. 28. Jukes had been somewhat taken aback by the startling viciousness of the first squall. 29. Such is the prestige, the privilege, and the burden of command. 30. It unveiled the black figures of men caught on the bridge, heads forward, as if petrified in the act of butting. III. Reading Comprehension (30%) Directions: In this section there are four passages followed by a total of 15 multiple-choice questions. Read the passages carefully and then write your answers on your ANSWER SHEET. Passage One You may not have thought of it just this way, but the letter you write is part of you, and expression of your personality. Therefore to write letters that are mere patterns of form is to present a colorless personality. Letters, by their very nature, are too individual to be standardized. A letter may be absolutely perfect according to the standards of good taste and good form; but unless it also expresses something of the writer’s personality, it is not a good letter. In other words, don't be satisfied to write letters that are just correct and nothing more. Try to write letters that are correct for you... letters that are warm and alive with reflections of your own personality. And if this sounds like a platitude (陈词滥调), stop for a moment and think back over your recent correspondence. What was the most interesting letter you received? Was it a letter anyone could have written? Or was it a letter that instantly “came alive”as you read it—that brought the personality of the sender right into the room with you. 幼儿园中班游戏教案：猜拳游戏 “石头、剪子、布”是一个传统的民间游戏。针对中班幼儿对输赢结果敏感度不高的特点，本游戏通过让幼儿翻游戏卡片的动作，产生观察、思考和判断。出国留学网小编准备了以下内容“幼儿园中班游戏教案：猜拳游戏”，供大家参考！ 幼儿园中班游戏教案：猜拳游戏 目标： 1.观察游戏卡片上的图案，理解游戏中＂石头、剪子、布＂相互克制的关系。 2.在翻动、覆盖、叠加卡片的过程中提高判断能力和手眼协调能力。 准备： 1.自制16宫格游戏底板一块。 2.用KT板自制的并用透明胶包起来的＂石头、剪子、布＂单面图案卡片各5张，另外增加1张＂石头＂卡片，一共16张游戏卡片，所有游戏卡片的背 面为白底。 3.每张游戏卡片的大小与游戏底板16宫格的格子大小一致。 玩法： 1.两名幼儿游戏。游戏前，幼儿共同把＂石头、剪子、布＂游戏卡片打乱，然后将其图案朝下，任意覆盖在16宫格游戏底板上。 2.游戏时，一名幼儿先选择翻开任意一张游戏卡片，另一名幼儿也选择翻开一张游戏卡片，随后，幼儿要快速判断自己所翻的游戏卡片能否克制对方翻开的游戏卡片。如果能够克制，则可以把自己的卡片叠放在对方的卡片上，覆盖住它的图案，比如＂石头＂可以覆盖＂剪子＂，＂剪子＂可以覆盖＂布＂，＂布＂可以覆盖＂石头＂。如果两张卡片不能形成互相克制的关系，则保持原有的翻开状态。 3.两名幼儿依次轮流游戏，幼儿每翻开一张卡片，都要观察和判断自己的卡片能否将游戏底板上翻开的任意一张卡 片克制住。如果能克制住，则马上进行叠加，即覆盖在那张或那叠卡片上；如果没有能克制住的对象，就让卡片继续保持翻开状态。 4.当游戏底板上的卡片被全部翻完时，游戏双方就用猜拳方法来决定每次谁先行动。每次猜拳获胜者可以选择将游戏底板上任意一组形成相互克制关系的卡片叠加在一起。 5.当游戏底板上没有相互克制的卡片时，游戏结束。 6.最后，两名幼儿数数游戏底板上的卡片数，每叠卡片分别由几张卡片组成，比较每叠卡片的数量，多者为胜。 规则： 1.翻游戏卡片时，每次只能翻一张。一次猜拳游戏，胜出者也只能选择叠加一次。 2.叠加后的卡片应在被克制的一方格子内整齐放置，如果卡片倒下或超出格子，则需要重新叠放。 3.叠加的游戏卡片没有数量限制，只 大班体育游戏：猜拳跨步 活动目标： 1.遵守游戏规则，学习正确的猜拳与跨步。 2.两两合作，配合协调。 活动准备： 场地上贴好起止线、红蓝标记若干、课件。 活动过程： 1.热身操。（队形：半圆形，看到每一个幼儿） 喜欢运动吗？这儿有一段适合的音乐，找个空的地方跟着我一起动起来！ 2.谈话导入。 哇，运动的感觉真好！知道吗？我小时候除了和你们一样喜欢做运动，还喜欢玩各种有趣的游戏。比如老鹰捉小鸡、跳房子、踢毽子，还有猜拳跨步。你们想玩吗？今天，我们就来玩一个猜拳跨步的游戏，好吗？ 3.教师讲解游戏规则及玩法（队形：两竖排，让每一个幼儿看清楚游戏的玩法） 1 ————来源网络整理，仅供供参考 （1）玩这个游戏必须会猜拳会跨步，你们都会吗？ ①猜拳怎么猜？剪刀赢？布赢？石头赢？非常清楚，真棒！ ②跨步会吗？试试看？跨得又大又稳，真不错！ （2）怎么玩呢？请一个孩子和我一起先来玩一下！看仔细，我们是怎样玩的！ 这是起跑线，那是终点线。两个人站在起跑线上，然后猜拳，谁赢了，谁就往前跨一步，跨好后站着不能动，然后继续猜拳，最先到达终点的就是胜利者。明白了吗？ 注意：只有猜拳胜出的才能向前跨一步，然后向原地后转再进行猜拳，没有决定胜负前，不能移动。 （3）我和他谁会先到到终点呢？请看仔细！ 4.幼儿自主游戏2遍，教师观察指导。 （1）幼儿第一次两两合作玩游戏。 知道怎么玩了吗？找一个朋友，一起来玩一玩！ （2）交流遇到的问题，重申活动规则。 刚才玩的时候有没有遇到什么问题？谁来说一说？ （3）幼儿第二次两两合作玩游戏。 只有遵守规则，才能玩得快乐。换个朋友再来玩一玩。 ————来源网络整理，仅供供参考 2 Reading 1: This is Water 1. What’s the point of the fish story? The immediate point of the fish story is that the most obvious, ubiquitous, important realities are often the ones that are the hard est to see and talk about. 2. What is our natural default-setting, according to Wallace? Do you agree with him? If yes, give examples; if no, exampl es too, please. I am the absolute center of the universe, the real est, most vivid and important person in existence. Yes, I do. The worl d as you experience it is right there in front of you, or behind you, to the l eft or right of you, on your TV, or your monitor, or whatever. Other peopl e’s thoughts and feelings how to be communicated to you somehow, but your own are so immediate, urgent, real. 3. Is it possibl e for us to adjust our natural default-setting? If yes, how? And by the way, why should we adjust it? A: Yes, it is. We shoul d pay attention to what’s going on insid e me and stay alert and attentive instead of getting hypnotized by the constant monologue insid e your own head. what’s more, we shoul d l earn how to Think and how to d ecid e.The reason why shoul d we adjust it is that thinking in the way of d efault-setting that we experience the boring, frustrating, crowed parts of adult life. B: Yes, it is. Learning how to think------Learning how to exercise some control over how and what you think. It means being conscious and aware enough to choose what you pay attention to and to choose how you construct meaning from experience. If we d on’t adjust it, we will be total ly nosed. 4. What does it mean by ‘learn ing how to think’? And what is the justifiable way to think? Learning how to think really means l earning how to exercise some control over how and what you think. It means being conscious and aware enough to choose what you pay attention to and to choose how you construct meaning from experience. 5. What is the meaning of college education? Do you agree? If yes, further explains please, if no, define your meaning of college education and further illustrate it. Coll ege education is that it enabl es my tend ency to over-intell ectualize stuff, to get l ost in abstract argument insid e our head instead of simply paying attention to what’s going on right in front of us. 单元综合测试一 （L10）（上）P142 Some men drew the first slip which touched their fingers; others seemed to suspect that fate was trying to force on them a particular slip and when they bad drawn one a little way from the shoe would let it drop again and choose another. Time passed with incredible slowness, and the man called Voisin sat against the wall with the unlighted cigarette in his mouth paying them no attention at all. 有些人抽自己手指头碰到的第一个纸了。另一些人似乎怀疑是命运在试图强迫他们抽某一特定的纸条，因此当他们刚把一个纸条从鞋里抽出一点，又扔回去，再选另一张。时间过得令人难以置信地缓慢。叫瓦赞的那个人背靠着墙坐着，嘴上叼着未点燃的烟，丝毫没注意他人。 （L11）（上）P159 I imagined the picture on the wall without difficulty, and gave it a few deft touches, but this set me thinking of pictures in general, and then I remembered an art exhibition I had attended with my friend T. and what he said, and what I said, and I wondered how T. was faring these days, and whether his son was still at school. And so it went on, until I found myself meditating on cheese, or spiritualism, or the Rocky Mountains—but no sleep! 我想象挂在墙上的画倒是没有问题，然后我熟练地去扶正它。这会使我想到通常见到的画，然后我想起一个艺术展，那是和我的朋友T一起去的。我记得他说过什么话，然后我又说了什么话，然后我开始想T这一段时间会怎么样了，他的儿子是否还在念书。就这样继续下去，直到我不知不觉地想到奶酪或是唯灵论，或者落基山脉——就是睡不着！ （L6）（上）P76 When she saw that I didn’t like her reference to “people like you”, she stopped for a moment and then put he r hand on my arm. “Listen,” she said, “Magpie is happy new, finally. He is in good spirits, handsome and free and strong. He sits at the drum and sings with his brothers: he’s okay now. When he was saying all those things against the government and against the council, he became more and more ugly and embittered and I used to be afraid for him. But I’m not now. Please, why don’t you just leave it alone now?” 当她发现我不喜欢她提到“像你这样的人”时，她停了一下，然后把手放到我的胳膊上，说：“听我说，现在喜鹊终于高兴起来了。他情绪很好，很英俊、很自由、也很健壮。他和兄弟们一起坐在皮鼓前唱歌，他现在很正常。他总是说那些反对政府．反对印第安人事务委员会的话，说那些话时他就变得越来越可怕，越来越恼怒。我过去常因此而为他担忧，可是我现在不那样了。哦，我们还是顺其自然吧。” （L9）（上）P 124 The viewer is on a perpetual guided tour: 30 t the museum, 30 at the cathedral, 30 for a drink, then back on the bus to the next attraction—-except on television., typically, the spans allotted arc on the order of minutes or seconds, and the chosen delights are more often car crashes and people killing one another. In short, a lot of television usurps one of the most precious of all human gifts, the ability to focus your attention yourself, rather than just passively surrender it. 观众被领着进行无限期的游览：30分钟看博物馆，30分钟看大教堂，30分钟喝饮料，然后又回到车上，到下一个参观点。但是电视的时间是按分秒来计算的，而且所选的欣赏内 吉林省经济管理干部学院 吉林经济职业技术学院 2013-2014学年第一学期 课程设计 项目类别：游戏设计 设计题目：猜拳小游戏 班级： 学号： 姓名： 校内教师： 企业教师： 设计日期：2013年12月9 日——2013年12月20日 一、设计目标 首先是JAVA语言的初级编程。其次JAVA语言的猜拳小游戏的编程及设计。有JAVA平台软件eclipse的使用。并且使用软件eclipse对猜拳小游戏进行编程，设计游戏算法，实现游戏功能。 二、目标描述 程序总体介绍和设计要求程序使用J2SE语言编写，使用标准JDK平台编译和运行。程序使用已创建的类，设计并实现一个类来玩游戏。根据游戏规则玩家将和电脑进行比赛。 在这个课程设计中，我们做成了一个人机猜拳的小游戏。游戏与我们平时玩的“剪刀、石头、布”是一样的玩法，只不过是玩家与电脑进行猜拳，并且电脑是随机出拳的。 三、设计过程 总体设计 3.1 程序主要功能： 程序总体介绍和设计要求程序使用J2SE语言编写，使用标准JDK平台编译和运行。 程序使用已创建的PairOfDice类，设计并实现一个类来玩游戏。根据游戏规则玩家将和电脑进行比赛。 3.2本程序设计有一下几点设计要求： 1)用可视化编程控件实现该程序。 2)人和电脑对战，你输入石头或剪子或布后，电脑会说“你赢了”，“你输了”或“平”。 3)在游戏结束时，要显示你赢了多少局，电脑赢了多少局，你们平了多少局 3.3 用户动作事件描述： 1)进行游戏 2)清零 3)对本次游戏的用户和电脑数据进行清零，即重新开始游戏。 3.4程序中所用类说明 用户自定义类 类名：SmallGame 作用：实例化对象 主要成员变量： a.Frame myFrm // 定义主窗体 b.TextArea myText // 定义文本编辑区 c.Button BfontOK, Bfind, Breplace, Bnext, Bcancel //定义和创建各按钮 https://www.doczj.com/doc/5e9086770.html,bel Lf Lr, Ls //定义和创建各标签 e.MenuBar Mbbar //定义和创建主菜单 f.Menu Mfile,Medit,Mformation,Mhelp //定义和创建主菜单中的选项 g.Toolkit toolKit 全国2010年10月高等教育自学考试 高级英语试题 课程代码：00600 I. The following paragraphs are taken from the textbooks, followed by a list of words or expressions marked A to Y. Choose the one that best completes each of the sentences and write the corresponding letter on your Answer Sheet. One word or expression for each blank only. (25 points, 1 point for each) Today’s heroes—some of them, anyway—tell us they enjoy their 1 . “And I 2 to myself at the men and the ladies. Who never 3 of us billion-dollar babies.” The 4 “culture hero” who 5 that is Alice Cooper. If I said that being black is a greater 6 than being a woman, probably no one would 7 me. Why? Because “we all know” there is 8 against black people in America. That there is prejudice against women is an idea that still 9 nearly all men—and, I am afraid, most women—as 10 . There is, however, another 11 possessed by the best work, which is even more important as a 12 of happiness than is the exercise of 13 . This is the element of constructiveness. In some work, though by no 14 in most, something is built up which remains as a 15 when the work is completed. My own state of mind, when I left Watts eight years ago to take up the 16 year at Whittier College, was 17 . It was to me less of a 18 ; it was the stepping off point of an Odyssey that was to take me through Whittier College and Oxford University, to Y ale Law School, and back to Watts. I had 19 then, as now, to make Watts my 20 . Well, it’s a good life and a good 21 , all said and 22 , if you don’t23 , and if you know that the big wide world hasn’t 24 from you yet, no, not by a long way, though it won’t be long now. The float bobbed more violently than II. Each of the following sentences is given four choices of words or expressions. Choose the right one to complete the sentence and write the corresponding letter on your Answer Sheet. (15 points, 1 point for each) 26. The citizens are grateful to the government for the ______ environment. A. wholesome B. wholesale C. noisome D. tiresome 一、游戏名称：蒙眼作画 分10-15教具：眼罩、纸、笔，所需时间 是这样吗？在日常工作中因为看得见，人人都认为睁着眼睛要比闭着眼画得好，些问题时我但为什么总有些东西我们看不到？当发生这；我们自然是睁着眼的，我们的也许当我们闭上眼睛时，们有没有想过借助他人的眼睛，试着闭上眼睛，心敞开了。 目标： ．使队员明白单向交流方式和双向交流方式可以取得的效果不同。1 ．说明当我们集中所有的注意力去解决一个问题时，可以取得更好的效果。2 要求蒙着眼睛将他每人分发一份纸和笔，规则：用眼罩将所有队员的眼睛蒙上，们的家或指定的其它东西画在纸上，完成后让队员摘下眼罩，欣赏自己的杰作。讨论： ．为什么当他们蒙上眼睛，所完成的画并不像他们期望得那样？1 ．怎样是这些工作更容易些？2 ．在工作场所中，如何解决这一问题？3 变化： ．让每个你带上眼罩前将他们的名字写在纸的另一面，在他们完成画图后将所1有的纸挂到墙上，让队员挑选出他自己画的那幅。 ．教员用语言描述一样东西，让队员蒙着眼睛画下他们所听到的，然后比较他 2.们所画的图并思考 二、游戏名称：解手链 形式：10人一组为最佳 时间：20分钟 材料：无 适合对象：全体人员 活动目的：让队员体会在解决团队问题方面都有什么步骤，聆听在沟通中的重要性以及团队的合作精神。 操作程序： 1．培训师让每组圈着站成一个向心圈 2．培训师说：先举起你的右手，握住对面那个人的手；再举起你的左手，握住另外一个人的手；现在你们面对一个错综复杂的问题，在不松开的情况下，想办法把这张乱网解开。 3．告诉大家一定会解开，但答案会有两种，一种是一个大圈，另外一种是套着的环。 ．如果过程中实在解不开，培训师可允许队员决定相邻两只手断开一次，但再4次进行时必须马上封闭。 讨论： ．你开始的感觉怎样，是否感觉思路混乱？1 ．当解开一点以后，你的想法是否发生变化？2 ．最后问题解决以后，你是否感觉很开心？3全国2013年10月高等教育自学考试高级英语试题
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