Steps toward the power spectrum of matter. I.The mean spectrum of galaxies

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Five Years in the Life of Cygnus X-1 BATSE Long-Term Monitoring

Five Years in the Life of Cygnus X-1: BATSE Long-Term MonitoringW.S.Paciesas∗ .C.R.Robinson ,M.L.McCollough , S.N.Zhang ,B.A.Harmon and C.A.Wilson∗University of Alabama in Huntsville,AL35899Universities Space Research AssociationNASA/Marshall Space Flight Center,Huntsville,AL35812Abstract.The hard X-ray emission from Cygnus X-1has been monitored con-tinually by BATSE since the launch of CGRO in April1991.We present thehard X-ray intensity and spectral history of the source covering a period of morethanﬁve years.Power spectral analysis shows a signiﬁcant peak at the binaryorbital period.The20–100keV orbital light curve is roughly sinusoidal with aminimum near superior conjunction of the X-ray source and an rms modulationfraction of approximately1.7%.No longer-term periodicities are evident in thepower spectrum.We compare our results with other observations and discussthe implications for models of the source geometry.INTRODUCTIONCyg X-1,the prototypical galactic black hole,is one of the most intensively studied objects in the X-ray sky.Nevertheless,our understanding of its de-tailed nature has been slow to evolve,due in large part to the strong but rather chaotic variability of its X-ray emission.Long-term monitoring in soft X-rays has been performed by several instruments,including the all sky mon-itors on Ariel5[4],Vela5B[11],and Ginga[5].These have identiﬁed two main periodic components in Cyg X-1,the5.6day binary orbital period and a less well deﬁned period of∼300days[11],the cause of which is speculative. The now well-known soft(“high”)and hard(“low”)emission states were also identiﬁed from soft X-ray data.Such states are now known to be common features of black holes,although not all black hole candidate systems have shown both states(e.g.,GS2023+33,LMC X-1).With CGRO/BATSE we have now accumulated more than5.5years of monitoring of Cyg X-1in hard X-rays.Moreover,since the launch of RXTE we now have wide band long-term monitoring of Cyg X-1.This enabled usc 1995American Institute of Physics12to obtain the most comprehensive observations yet of a complete soft state episode[14].We report here exclusively on the BATSE long-term monitoring, including a broad overview of the intensity and spectral variability and our search for periodic or quasi-periodic components.OBSER V ATIONSData obtained between21Apr1991and24Sep1996(TJD8367–10350) were processed using the standard BATSE Earth occultation software.Fluxes in the energy range20–100keV were calculated byﬁtting standard spectral models to the16-channel count spectra,either from individual occultation steps or summed over one day.Two models were used:a single power-law and an optically thin thermal bremsstrahlung(OTTB).In general,our conclusions do not depend signiﬁcantly on the choice of model spectrum.Figure1shows the long-term intensity and spectral history of Cyg X-1 in the20–100keV energy range using one-day integrations.The two previ-ously known soft state episodes are clearly visible around TJDs9350–9410 and10220–10300.During the remaining time,the source intensity in the hard stateﬂuctuated rather randomly,staying mostly between0.2and0.35ph cm−2 s−1.The hard state spectral index remained relatively steady around a value near−1.85,although extended periods with slightly softer spectra occur,e.g., TJD8950–9030.Flares above the0.35ph cm−2s−1level typically last only a few days and show no spectral diﬀerentiation,whereas dips below the0.2ph cm−2s−1level typically last a week or so,and may or may not show spectral softening(cf.the intensity dips around TJDs9510and9610).FIGURE1.Long-term hard X-ray intensity and spectral history of Cyg X-1from BATSE observations.The upper panel shows the integrated photonﬂux in the20–100keV band derived byﬁtting a power-law model to one-day average count spectra.The lower panel shows the corresponding photon number spectral index.3FIGURE 2.Correlation plot of spectral in-dex vs.photon number ﬂux using the same data as in Figure 1.For clarity,the ﬂux er-rors are notshown.FIGURE 3.The power density spectrum of Cyg X-1hard X-ray ﬂux,computed from sin-gle occultation step measurements using theScargle algorithm [13]for unevenly sampleddata.Figure 2shows a plot of the spectral index vs.ﬂux for the same data set.The predominance of the −1.85spectral index over a wide range of intensities is obvious,as is the trend toward softer spectral indices at low intensity.How-ever,the hard state can persist down to intensities as low as 0.15ph cm −2s −1and spectra as soft as α −2.2can be present at essentially any intensity.Spectra with α<∼−2.2are mainly conﬁned to ﬂux levels below ∼0.15ph cm −2s −1,which appear to occur only during the low energy “high”states.We do not see well-deﬁned intensity/spectral states corresponding to the three-state classiﬁcation scheme outlined by Ling et al.[6].To search for periodic and quasi-periodic signals,we used ﬂuxes deconvolved in a similar manner,but at the resolution of individual occultation steps.We present results using the OTTB model,which produced slightly more robust ﬁts.The unevenly sampled power density spectrum (PDS)(Figure 3)is rather ﬂat at low frequencies,falls oﬀroughly as 1/f above ∼0.005cycle/day (200day period),and reaches the Poisson noise level at f 0.4.To estimate the signiﬁcance of peaks in the data,we ﬁrst ﬁt the data with a combination of a constant power Z 0at low frequencies and a power-law a 0f a 1above a break frequency f c .The resulting parameters were Z 0=148,a 0=0.333,a 1=−1.117,and f c =0.00425.After dividing by the red noise ﬁt,the maximum of the power spectrum is at f =0.178606,consistent with the binary orbit f =0.178580[2].Treating this as an a priori interesting frequency,the probability of a chance ﬂuctuation is 1.4×10−7.If we ignore the a priori argument and scale by the number of independent trial frequencies,the chance probability is 5.4×10−5.Our data show no evidence for a peak around f =0.0033(300day period);however,our sensitivity below ∼0.01Hz is limited by the red noise.Figure 4shows the data folded at the orbital period.The modulation is4roughly sinusoidal,with a minimum near phase0(supergiant companion near-est the observer).The best-ﬁtting sine function has a minimum at phase 0.025±0.008and peak-to-peak amplitude0.0094±0.0004ph cm−2s−1(sta-tistical errors only),which corresponds to3.8%of the average intensity.The rms scatter about the mean is∼1.7%.DISCUSSIONDetection of the5.6day orbital variation in hard X-rays wasﬁrst reported by Ling et al.[7],who found a peak-to-peak amplitude of∼6%in50–140 keV using∼120days of data from the HEAO-3gamma ray spectrometer. Priedhorsky et al.[12]reported a marginal detection of10±4%in17–33 keV from∼70days of observations with WATCH/Eureca.Phlips et al.[10], using∼120days of CGRO/OSSE data,did notﬁnd a signiﬁcant variation in60–140keV,with an upper limit to the rms fraction of5%.Our result is consistent with the OSSE upper limit,and marginally consistent with the earlier observations.FIGURE4.Cyg X-1single occul-tation step data folded at the5.6daybinary orbital period.Two cycles areshown for clarity.The best-ﬁttingsine function is superimposed.Errorbars represent the statistical error inthe mean for each phase bin.Phase0corresponds to the time when the su-pergiant companion is closest to ourline of sight.Since the low energies show obvious absorption dips near phase0[4,8,9], it is natural to consider absorption as responsible for the variation we see. The decrease in our data centered roughly around phase0cannot be due to absorption by cold matter because the column density required would cause a total eclipse of the soft X-rays,which is not observed.Electron scattering by highly ionized material would require a maximum column density∼6×1024 cm−2.If the material is in a stellar wind,the nearly sinusoidal shape we observe implies that this material is spread over a large portion of the orbit. This is inconsistent with the much lower column density( 3×1023cm−2) estimated for such a wind from9–12keV data[12].An alternative possibility is a variable reﬂection component from the accre-tion disk or the companion star.Done et al.[1,also see ref.[3]]showed that the Cyg X-1spectrum can beﬁt with a model involving reﬂection from an ionized accretion disk,similar to models for active galactic nuclei.In theseﬁts,5the reﬂection component represents∼30%of theﬂux in the20–100keV range, so that our results could be explained by a variation of5–10%in reﬂectivity as a function of phase.SUMMARYBATSE has observed Cyg X-1continually for more than5.5years.The hard X-ray light curve is dominated by red noise that has aﬂat power spectrum below a frequency of∼0.004cycle/day(periods 250days)and falls oﬀroughly as1/f at higher frequencies.Periodic variability is detected at the binary orbital period,with an rms modulation of∼1.7%and a minimumﬂux at the time of superior conjunction of the supergiant companion(phase0).We ﬁnd no evidence for the previously reported long-term period of∼300days. The20–100keV spectrum of Cyg X-1appears to have a spectral hardness limit around a power-law indexα −1.8.BATSE has observed such a spectrum over aﬂux range of at least a factor of three,from∼0.15to>∼0.45 ph cm−2s−1.However,softer spectra can be present at any observedﬂux level.Below∼0.15ph cm−2s−1,only soft spectra(α<∼−2.25)associated with the soft(high)X-ray state have so far been seen.REFERENCES1.Done,C.,et al.1992,ApJ395,2752.Gies,D.R.,&Bolton,C.T.1982,ApJ260,2403.Haardt,F.,et al.1993,ApJ411,L954.Holt,S.S.,et al.1979,ApJ233,3445.Kitamoto,S.,et al.1997,preprint6.Ling,J.C.,et al.1983,ApJ275,3077.Ling,J.C.,et al.1990,Proc.21st ICRC,Adelaide,Vol.1,p.1978.Mason,K.O.,et al.1974,ApJ192,L659.Murdin,P.1975,in X-Ray Binaries,NASA SP-389,p.42510.Phlips,B.F.,et al.1996,ApJ465,90711.Priedhorsky,W.C.,et al.1983,ApJ270,23312.Priedhorsky,W.C.,et al.1995,A&A,300,41513.Scargle,J.D.1982,ApJ263,83514.Zhang,S.N.,et al.1997,ApJ477,L95。

Discovery of 0.08 Hz QPO in the power spectrum of black hole candidate XTE J1118+480

a r X i v :a s t r o -p h /0005212v 1 10 M a y 2000A&A manuscript no.(will be inserted by hand later)ASTRONOMYANDASTROPHY SICS1.IntroductionThe transient X-ray source XTE J1118+480was discov-ered with the RXTE All-Sky Monitor on March 29th,2000.Subsequent RXTE pointed observations revealed a power law energy spectrum with a photon index of about 1.8up to at least 30keV.No X-Ray pulsations were detected (Remillard et al.,2000)In hard X-rays the source was observed by BATSE up to 120keV (Wil-son&McCollough 2000).Uemura,Kato &Yamaoka(2000)reported the optical counterpart of 12.9magnitude in un-ﬁltered CCD.The optical spectrum was found typical for the spectrum of an X-Ray Nova in outburst (Garcia et al.2000).Pooley &Waldram (2000)using Ryle Telescope detected a noisy radiosource with ﬂux density of 6.2mJy at 15GHz.All existing observations show that XTE J1118+480is similar to the black hole transients in close binaries with a low mass companion.50503-01-01-00Mar.2922:510.750407-01-01-00Apr.1309:28 5.050407-01-01-01Apr.1314:18 3.150407-01-02-00Apr.1507:51 1.150407-01-02-01Apr.1704:44 4.150407-01-02-02Apr.1819:21 1.050407-01-02-03Apr.1821:27 1.850407-01-03-01Apr.2420:350.750407-01-03-02Apr.2701:570.950407-01-04-02May 111:25 1.850407-01-04-01May 405:15 1.02Revnivtsev,Sunyaev &Borozdin:QPO in XTEJ1118+480Fig.1.The RXTE/ASM light curve (1.3-12.2keV)of the transient XTE J1118+480.Arrows show the dates of RXTE pointed observations,used in our analysis.3.ResultsThe power spectrum of XTEJ1118+480with a strong QPO feature is shown in Fig.2.The simplest Lorenz approximation of the detected QPO peak gives the cen-troid frequency 0.085±0.002Hz and the width 0.034±0.006Hz (the Q parameter ∼2–3).The amplitude of the QPO ≈10%rms.The power density spectrum (PDS)of the source is typical for a black hole candidates in the low/hard spectral state.The power spectrum is almost ﬂat at frequencies below ∼0.03Hz,roughly a power law with slope ∼1.2from 0.03to 1Hz with following steepen-ing to slope ∼1.6at higher frequencies.The total ampli-tude of detected variability of the source is close to 40%rms.We did not detect any X-ray variability of the source ﬂux at the frequencies higher than ∼70Hz.The 2σup-per limits on the kHz QPOs in the frequency band 300–1000Hz are of the order of 5–6%for QPO with quality Q ∼10,this is in 1.5–3times lower than typical ampli-tudes of observed kHz QPOs in the neutron star PDSs (e.g.van der Klis 2000).Our preliminary analysis of the XTE J1118+480ra-diation spectrum conﬁrms that it is very hard:it was detected by High Energy Timing Experiment (HEXTE)up to energies of ∼130–150keV with the power law slope α∼1.8with possible cutoﬀat the highest en-ergies (>∼130keV)The spectrum of XTE J1118+480is very similar to that of the transient source GRS 1737–37(Sunyaev et al.1997,Trudolyubov et al.1999a,Cui et al.1997).A detailed spectral analysis of XTE J1118+480will be presented elsewhere.Fig.2.Power spectrum of XTE J1118+4804.DiscussionLow frequency QPO peaks were reported earlier in the power spectra of several black hole candidates in their low/hard state –at ∼0.03–0.07Hz with Q ∼1for Cyg X-1(Vikhlinin et al.1992,1994,Kouveliotou et al.1992a),at ∼0.3Hz for GRO J0422+32(Kouveliotou et al.1992b,Vikhlinin et al.1995),∼0.8Hz for GX 339-4(e.g.Grebenev et al,1991)and in the high/soft state of LMC X-1(Ebisawa,Mitsuda &Inoue 1989)and XTE J1748–288(Revnivtsev,Trudolyubov &Borozdin 2000).Impressive QPOs with harmonics were observed in the power spec-tra of Nova Muscae 1991(e.g.Takizawa et al.1997,Belloni et al.1997),GRS 1915+105(e.g.Greiner et al.1996,Trudolyubov et al.1999b).The detection of low fre-quency QPO in the power spectrum of XTE J1118+480allows us to add another black hole candidate to this sam-ple.In all these cases the QPO peak lies close to the ﬁrst (low frequency)break in the power spectrum (see also Wijnands &van der Klis 1999).The optical counterpart of XTE J1118+480is suﬃ-ciently bright to check for the presence of corresponding low frequency optical variability with f ∼0.085Hz.The power spectra of black hole candidates are dras-tically diﬀerent from those of neutron stars in LMXBs in similar low/hard spectral state.Sunyaev and Revnivt-sev (2000)presented a comparison of power spectra for 9black hole candidates and 9neutron stars.None of the black hole candidates from this sample show a signiﬁcant variability above ∼100Hz,while all 9neutron stars were noisy well above 500Hz,with the signiﬁcant contribution of high-frequency noise f >150Hz to the total variability of the source.The power spectrum of the newly discov-Revnivtsev,Sunyaev&Borozdin:QPO in XTE J1118+4803 ered X-ray transient XTE J1118+480(see Fig2)looksvery similar to other black hole PDSs(see Fig.1of Sun-yaev and Revnivtsev,2000).The detection of low frequency QPO,lack of high-frequency noise and a hard energy spectrum detected upto∼150keV in X-rays are supportive arguments for theearlier identiﬁcation of XTE J1118+480as a black holecandidate.Acknowledgements.This research has made use of dataobtained through the High Energy Astrophysics ScienceArchive Research Center Online Service,provided by theNASA/Goddard Space Flight Center.The work has been sup-ported in part by RFBR grant00-15-96649.ReferencesBelloni T.,van der Klis M.,Lewin W.H.G et al.1997,A&A322,857Cui W.,Heindl W.,Swank J.et al.1997,ApJ,487,73Ebisawa K.,Mitsuda K.,Inoue H.1989,PASJ,41,519Garsia M.,Brown W.,Pahre M.,J.McClintock2000,IAUC7392Grebenev S.,Sunyaev R.,Pavlinsky M.et al.1991,SvAL17,413Greiner J.,Morgan E.,Remillard R.1996,ApJ473,107Kouveliotou,Finger&Fishman et al.1992a,IAUC5576Kouveliotou,Finger&Fishman et al.1992b,IAUC5592Pooley G.G,Waldram E.M.,2000,IAUC7390Remillard R.,Morgan E.,Smith D,Smith E.2000,IAUC7389Revnivtsev M.,Trudolyubov S.,Borozdin K.2000,MNRAS312,151Sunyaev R.,Churazov E.,Revnivtsev M.et al.1997,IAUC6599Sunyaev R.,Revnivtsev M.2000,A&A in press,astro-ph/0003308Takizawa M.,Dotani T.,Mitsuda K.et al.1997,ApJ489,272Trudolyubov S.,Churazov E.,Gilfanov M.et al.1999a,A&A,342,496Trudolyubov S.,Churazov E.,Gilfanov M.et al.1999b,Astr.Lett.25,718Uemura M.,Kato T.,Yamaoka H.2000,IAUC7390van der Klis M.2000,ARA&A in press,astro-ph/0001167Vikhlinin A.,Churazov E.,Gilfanov M.et al.1992,IAUC5576Vikhlinin A.,Churazov E.,Gilfanov M.et al.1994,ApJ,424,395Vikhlinin A.,Churazov E.,Gilfanov M.et al.1995,ApJ,441,779Wijnands R.,van der Klis M.1999,514,939Wilson C.&McCollough M.2000,IAUC7390Zhang W.,Morgan E.,Jahoda K.,Swank J.,Strohmayer T.,Jernigan G.,Klein R.,1996,ApJ,469,29L。

911改变了世界中英译文

“9. 11”事件前后泰-摩西As the ruins of the World Trade Towers smoldered at the southern end of Manhattan and the breez e stirred the ashes of thousands of human beings, a new age of anxiety was born. If someone had s lept through September 11 and awakened, Rip Van Winkle-like today, he would open his eyes on a n astonishing new landscape.1．世贸大厦双塔的废墟还在曼哈顿区南端闷燃，微风将几千人的身躯化成的灰烬吹起，一个新的焦虑时代由此开始。

如果有人在9月11日那天像瑞普?凡?温克尔那样恰好睡去，一觉醒来，眼前的这一派景象定让他瞠日结舌。

Guardsmen toting M-16s are stationed at our airports. The president of the United States attends a World Series game and the airspace over Yankee Stadium is closed, a line of snipers positioned on the stadium rooftop. The vice-president's safekeepers whisk him from place to place, just as his ar ch-nemesis Osama bin Laden is presumably moved from cave to cave halfway across the world. A nthrax panic sends Congress running from its chambers.2．机场里驻进了背着V-16自动步枪的国民警卫队员。

材料科学中的几本重要杂志

材料科学，主要包含金属、陶瓷、复合材料等，高分子的一般是在化学里面。

1。

acta materialia这个应该算是材料科学中影响力最大的期刊了吧，。

2002 年的if是3.104。

1953年开始的。

原来封面是4个圈的，2004年中间开始多了一个圈（theory）。

paper都很长的，大都在7page以上吧，现在没有letters的。

同一个出版社的还有个scripta materialia。

Acta Materialia's purpose is to publish original papers and occasional critical reviews which advance the understanding of the structural and functional properties of materials: metals and alloys, ceramics, high polymers and glasses. Emphasis is placed on those aspects of the science of materials that are concerned with the relationship between the structure of solids and their properties (mechanical, chemical, electrical, magnetic and optical); with the thermodynamics, kinetics and mechanisms of processes occurring within solids; with experiments and models which help in understanding the macroscopic properties of materials in terms of microscopic mechanisms; and with original work which advances the understanding of structural and functional materials./JournalDetail.html?PubID=221&Precis=DESC/science/journal/135964542。

Power-spectrum condition for energy-efficient watermarking

x w n ~
1 Also called cover data" or host data."
watermarked document
y~ n
-
estimated attacked watermark + document ^ n g -g ^n w ~ - , y ~ Wiener ? lter h~ n 6 +6 gain additive factor noise
Hale Waihona Puke ABSTRACTattacks. However, others have proposed placing the watermark in the middle or high frequencies to make it easier to separate from the original image 7, 8 or making it white, as in conventional spread spectrum. This paper elaborates on a simple theoretical watermarking and attack model from 9 . Analysis leads to a meaningful way to evaluate robustness. It is shown that watermarks that resist the attack should satisfy a powerspectrum condition. Finally, experiments with theoretical signal models and natural images verify and reinforce the importance of this condition.

CommScope ServAssure NXT Performance Management 说明

Page of 12Intelligent performance management for PON and HFC networksCommScope’s ServAssure NXT solution suite provides end-to-end visibility across the entire service delivery environment, helping operators find and resolve problems before they impact the subscriber, and optimize operations to improve customer experience Organizations transforming their networks, evolving toward distributed architectures and next generation access technologies, are controlling the complexity and achieving success with ServAssure NXT software. Maintaining home grown and open-source solutions has proven unsustainable as technology advances often outpace in-house development efforts.How it works:ServAssure NXT Performance Management combines intelligent analytics with CommScope’s domain expertise to help service providers unleash the power of data to prevent and solve performance issues.First, key performance information about the network, field service, and subscribers, is collected, normalized, and enriched, making it available to the organizations and applications that rely on it.Then, an AI-driven platform is provided for deep analytics, helping you unlock key insights about your physical HFC and PON network, service quality, bandwidth & capacity risks, service theft, and upsell opportunities, guiding sound decisions and prudent investments.Proven Benefits:Increase customer satisfaction and lower the volume of calls to your call centerDiscover and resolve plant issues before subscribers are impactedReduce OpEx dramatically via smarter and fewer truck rollsImprove quality of technician visits and Mean Time To RepairSave IT and ops expense through consolidation of OSS tools and processes Minimize risk during network transformation processThe ServAssure NXT software portfolio includes the following:provides service performance trending, risk analysis, and troubleshooting across HFC & FTTx networks – ServAssure® NXT - Analyze including high-rate graphing, real time tools, and the ability to drill down from enterprise & regional view down to individual neighborhoods and devices easily.delivers automated identification and prioritization of existing and potential service impairments - ServAssure®NXT - Alarm Central Network Outage Management, Proactive Networking Monitoring, Fast Outage Detection, and Intelligent Spectrum Analyzer.provides business intelligence, big data visibility, integration, and export.ServAssure®NXT - Insight allows for flexible and reliable telemetry collection, real-time requests, and data enrichment.ServAssure®NXT - Collection Platform ServAssure NXT has been deployed globally. It’s open and modular, architected to address the reliability standards of tier-one serviceServAssure NXT has been deployed globally. It’s open and modular, architected to address the reliability standards of tier-one service providers, but lean enough to support smaller organizations. The system is highly configurable, and it can be deployed onsite, a growing number of operators are opting for the SaaS model – deployed in the cloud and fully managed by CommScope.As an open system, ServAssure NXT provides multiple paths for integration. Streaming telemetry is available for organizations that requirea common, centralized collection source, highly performant APIs are available for real time queries & actions, bulk historical data is available from ServAssure’s data lake, and highly customizable notifications allow operators to receive alarms programmatically.With patented "finger-printing", and health scoring for plant & home visibility, ServAssure NXT provides organizations with a centralizedplace to view service delivery in a normalized way, across all hardware vendors and access technologies.How we work:The ServAssure software team leverages a development operations (DevOps) approach to deliver its software solutions with the highest possible quality, while speeding the delivery of new features and updates. By fostering a culture of constant communication throughoutthe product development lifecycle, and leveraging automated continuous build and test processes, the ServAssure team delivers an ever-expanding roadmap – providing continuous value to customers.Product ClassificationRegional Availability Asia | Australia/New Zealand | EMEA | Latin America | North AmericaProduct Type Service assurance software22Page of。

物理英文词汇

A a.c. generator 交流发电机aberration 光行差，像差absolute index of refraction 绝对折射率absolute refractive index 绝对折射率absolute temperature scale 绝对温标absolute zero 绝对零度absorber 吸收体absorbing power 吸收能力，吸收本领absorptance 吸收比absorption 吸收absorption coefficient 吸收系数absorption line 吸收谱线? absorption spectrum 吸收光谱，吸收谱accelerate 加速acceleration 加速度acceleration due to gravity 重力加速度acceleration-time graph 加速度—时间关系线图accelerator 加速器acceptor 接受体acceptor doping 受体掺杂acceptor impurity 受体杂质accommodation 调节，视觉调节accumulator 蓄电池accuracy 准确度acetate strip 醋酸酯条片achromatic 消色差的achromatic aberration 消色差achromatic condenser 消色差聚光透镜achromatic light 消色差光，白光acoustic blur 声响模糊acoustic board 吸音板，吸声板acoustic navigation 声响导航acoustic pressure 声压acoustics 声学act on 施于action 作用量，作用，作用力action of point 尖端作用activation 激活，活化activation energy 激活能，活化能active nucleus 活性核，放射性核activity 放射强度，放射性adapter 接合器adder 加法器adhesion 附着力，附着，黏附adhesive force 附着力adiabatic 绝热的adiabatic expansion 绝热膨胀adiabatic process 绝热过程aerial 天线? aerial induction 天线调谐电感aerial network 天线网络aerodynamic force 气动力，空气动力aerodynamics 气体动力学，空气动力学aerofoil 机翼agent 剂air blower 吹风器air column 空气柱，气柱air cushion 气垫air damping 空气阻尼air film 气膜air track 气垫导航air wedge 气楔alignment 对准，校整alpha decay α衰变alpha pa rticle α粒子alpha particle scattering analogue α粒子放射模拟alternating current 交流电alternating voltage 交变电压，交流电压alternator 交流发电机altimeter 高度计，测高仪americium ?? ammeter 安培计amorphous 非结晶的，无定形的ampere 安培，安ampere-hour 安培小时，安时amplification 放大，放大率amplifier 放大器amplify 放大amplitude 振幅amplitude modulation 调幅，振幅调剂amyl acetate 醋酸戊酯anaemia 贫血analogue 模拟analogue experiment 模拟实验analogue signal 仿真讯号，非数字讯号analogue-to-digital conversion 模拟转换analyser 检偏振器AND gate 「与」门anemometer 风速计aneroid barometer 无液气压计，空盒气压计angle of contact 接触角angle of deviation 偏向角angle of diffraction 衍射角，绕射角angle of dip 倾角angle of elevation 仰角angle of emergence 出射角angle of incidence 入射角angle of inclination 倾角angle of minimum deviation 最小偏向角angle of projection 投射角angle of reflection 反射角angle of refraction 折射角angle of twist 扭转角angstrom 埃angular acceleration 角加速度angular aperture 孔径张角angular displacement 角位移angular frequency 角频率angular impulse 角冲量angular magnification 角度放大，角放大率angular momentum 角动量，动量矩angular motion 角向运动，角运动angular seed 角速率angular velocity 角速度angular width 角宽度annealing 退火，韧化anode 阳极，正极anomalous expansion 反常膨胀antenna 天线? anticlockwise moment 逆时针力矩antifreeze 防冻剂antinodal line 腹线? antinode 波腹antiparticle 反粒子antiphase 反相，逆相aperture 孔径，口径，孔apparent depth 视深apparent expansion 表观膨胀，视膨胀apparent frequency 表观频率，视频率apparent loss in weight 表观失重apparent weight 表观重量Appleton layer 阿普顿层，F电离层aqueous layer 水层Archimedes? principle 阿基米得原理area 面积argon 氩armature 电枢artificial disintegration 人工蜕变artificial radioactivity 人工放射astable 非稳态的astable circuit 非稳态电路astable multivibrator 非态多谐振荡器astigmatism 像散，散光astronomical telescope 天文望远镜at infinity 在无穷远处at rest 静止atmosphere 大气，大气层，大气压atmospheric pressure 大气压强atom 原子atomic bomb 原子弹atomicbond 原子键atomic density 原子密度atomic diameter 原子直径atomic energy 原子能atomic mass 原子质量atomic mass unit 原子质量单位atomic model 原子模型atomic nucleus 原子核atomic number 原子序数atomic radius 原子半径atomic separation 原子间距atomic spacing 原子间距atomic structure 原子结构atomic theory 原子论atomizer 喷雾器attenuation 衰减attraction 吸引attractive force 吸力audible frequency range 听频范围audible signal 可听讯号audio frequency 声频autofocus 自动聚焦，自动对焦avalanche 电子雪崩average acceleration 平均加速度average power 平均功率average speed 平均速率average velocity 平均速度Avogadro constant 阿佛加德罗常数，阿佛加德罗常量Avogadro number 阿佛加德罗数Avogadro?s law 阿佛加德罗定律axial 轴向的，沿轴的axial field 轴向场axial search coil 轴向探察线图axis 轴axis of rotation 转轴B back e.m.f. 反电动势background radiation 本底辐射Bainbridge mass spectrometer 班布里奇质谱仪balance 天平，秤，平衡balance arm 秤杆，平衡臂balance point 平衡点balance bridge 平衡电桥balanced force 平衡力ball bearing 球轴承，滚珠轴承ballistic galvanometer 冲击电流计，冲击检流计ballistic pendulum 冲击摆Balmer series 巴耳末系，巴耳末光谱band spectrum 带状光谱，带状谱bandwidth 带宽bar code 条形码bar magnet 磁棒bare wire 裸线? barium 钡barometer 气压计barrier 障碍物barrier layer 阻档层，耗尽层barrier potential difference 阻档层电势差，阻档层电位差Barton?s pendulums 巴尔通摆base 基极base current 基极电流battery 电池组battery charger 电池充电器battery holder 电池座beaker 烧杯beam splitter 分束器，射束分离器beat 拍beat frequency 拍频becquerel 贝克勒耳，贝克bel 贝尔，贝bell jar 钟形罩bench mat 实验台垫Bernoulli?s theorem 伯努利定律beryllium 铍beta decay β衰变beta particle β粒子biasing circuit 偏压电路biasing voltage 偏压biconcave lens 双凹透镜biconvex lens 双凸透镜bicycle dynamo 自行车发电机，脚踏车发电机bifilar pendulum 双线摆bifocal lens 双焦距透镜big bang model 大爆炸模型bimetallic strip 双层金属片，双金属片binary adder 二进加法器binary system 二进制binding 结合binding energy 结合能binoculars 双筒望远镜Biot-Savart law 毕奥—萨伐尔定律bipolar 双极的birefraction 双折射bistable 双稳态的，双稳器bistable circuit 双稳电路bistable multivibrator 双稳态多谐振荡器bit 二进制制，位black body radiation 黑体辐射block and tackle 滑轮组block diagram 方框图blocking capacitor 隔直流电器容blooming 敷霜，表面加膜Bohr atom 玻尔原子Bohr radius 玻尔半径Bohr theory 玻尔理论boil 沸腾，煮沸boiler 锅炉boiling point 沸点bolometer 辐射热计Boltzmann constant 玻耳兹曼常数，玻耳兹曼常量bombardment 轰击bond energy 键能bonding 键合Bourdon gauge 布尔登气压计bow wave 弓形波，舷波Boyle?s law 博伊尔定律Brackett series 布喇开系，布喇开光谱Bragg angle 布喇格角Bragg diffraction 布喇格衍射，布喇格绕射Bragg plane 布喇格平面Bragg?s law 布喇格定律brake 制动器breakdown potential 击穿电势，击穿电位breaking point 断点breaking strength 抗断强度breaking stress 致断应力breeder reactor 增殖反应堆bremsstrahlung 轫致辐射Brewster?s law 布鲁斯特定律bridge circuit 桥式电路bridge rectifier 桥式整流器bright fringe 亮纹brightness 亮度brittle 脆的，易碎的bromine 溴Brownian movement 布朗运动brush 电刷bubble chamber 气泡室bubble raft model 泡筏模型buffer 缓冲器buffer circuit 缓冲电路bulk modulus 体积弹性模量Bunsen burner 本生灯buoyancy 浮力burette 滴定管burette stand 滴定管架burglar alarm 防盗警报器，防盗警钟buzzer 蜂鸣器by-pass 旁路byte 二进制组，字节C cable 电缆cadmium sulphide 硫化镉caesium 铯calcite 方解石calibrate 校准，标上刻度calipers 测径器，卡钳calorie 卡路里，卡calorimeter 量热器camera 照相机cancer cell 癌细胞candela 坎德拉cantilever 悬臂capacitance 电容capacitance substitution box 换值电容箱capacitive circuit 电容电路capacitive component 电容性分量capacitive coupling 电容耦合capacitive discharge 电容性放电capacitive reactance 容抗capacitor 电容器capacitor-input filter 电容输入滤波器capacity 容量，载量capillarity 毛细现象，毛细作用capillary depression 毛细下降capillary rise 毛细上升capillary tube 毛细管capsule 囊capture 俘获carbon 碳carbon granule 碳颗粒carbon paper disc 圆形碳纸carbon-14 dating 碳14年代测定法carburettor 化油器，汽化器carrier wave 载波carry 进位castor oil 蓖麻油cataract 白内障cathode 阴极，负极cathode ray 阴极射线? cathode ray deflection tube 阴极射线偏转管cathode-ray oscilloscope 阴极射线示波器，示波器cathode-ray tube 阴极射线管cavity resonator 空腔共振器celestial telescope 天体望远镜cell 电池，细胞Celsius temperature scale 摄氏温标centimetre 厘米centralized low voltage power supply unit 中央控制低压电源箱centre of curvature 曲率中心centre of gravity 重心centre of mass 质心centre of oscillation 振荡中心centre-tapped transformer 中心抽头变压器centrifugal force 离心力centrifuge 离心机centripetal acceleration 向心加速度centripetal force 向心力Chadwick 查德威克chain reaction 连锁反应change of state 物态变化change-over switch 换向开关characteristic 特性，特征characteristic curve 特性曲线? characteristic line 特征线，特征谱? characteristic spectrum 特征光谱，特征谱charge 电荷，充电，起电charge carrier 载荷子charge conservation 电荷守恒charge density 电荷密度charge distribution 电荷分布charge to mass ratio 荷质比charged particle 带电粒子charging by contact 接触起电charging by friction 摩擦生电charging by induction 感应起电charging by sharing 授受起电charging time constant 充电时间常数，充电时间常量Charles?s law 查理定律choke 扼流，抗流，扼流圈，抗流圈choke circuit 扼流电路，抗流电路chromatic aberration 色差chromatic dispersion 色散cinefilm soundtrack 电影胶片声迹circle of least confusion 最少模糊圈，明晰圈circuit 电路circuit board 电路板circuit breaker 断路器circuit symbol 电路符号circular coil 环形线圈circular motion 圆周运动circular orbit 圆周轨道circular pulse 圆形脉冲circular wave 圆形波circular wavefront 圆形波阵面，圆形波前clamp 夹钳，夹紧clap-echo method 「拍掌—回声」法cleave 裂开clinical thermometer 体温计clip 夹子clockwise moment 顺时针力矩closed circuit 闭合电路closed pipe 闭管closed tube 闭管closed-loop control system 死循环控制系统closed-loop gain 死循环增益closed-loop voltage gain 死循环电压增益closely packed 密堆积的cloud chamber 云室cloud chamber track 云室径迹coaxial 共轴，同轴coaxial cable 同轴电缆，同轴? cobalt 钴code 编码coder 编码器coefficient of dynamic friction 动摩擦系数coefficient of friction 摩擦系数coefficient of restitution 恢复系数coefficient of static friction 静摩擦系数coefficient of viscosity 黏滞系数coherent 相干的cohesion 内聚力，内聚cohesive force 内聚力coil 线圈collector 集电极，集极collector current 集电极电流，集极电流collimator 准直管，准直仪collision 碰撞colour 颜色colour code 色码，色标combinational logic 组合逻辑common emitter 共发射极common-mode voltage 共模电压commutator 换向器compass 指南针，罗盘complete circuit 完整电路component 组件，分量，组分component of force 分力compound microscope 复式显微镜compound pendulum 复摆compressed gas 压缩气体compressibility 可压缩性，压缩系数，压缩率compressible fluid 可压缩性流体compression 密部，压缩compression spring balance 压缩弹簧天平concave 凹concave lens 凹透镜concave mirror 凹镜，凹面镜concentric capacitor 同心电容器condensation 凝结，凝聚condensation nucleus 凝结核，凝聚核condensation point 凝点，凝结点condenser 聚光器，电容器，冷凝器conductance 电导conductivity 传导性，传导率conductor 导体conical pendulum 锥摆conjugate foci 共轭焦点conservation of angular momentum 角动量守恒conversation of charge 电荷守恒conservation of energy 能量守恒conservation of mechanical energy 机械能守恒conservation of momentum 动量守恒conservative force 守恒力，保守力conserved 守恒constant acceleration 恒加速度constant angular acceleration 恒角加速度constant angular velocity 恒角速度constant force 恒力constant motion 恒速运动constant pressure 定压constant speed 恒速率constant temperature 定温constant velocity 恒速度constant volume 定容constant volume gas thermometer 定容气体温度计constantan 康铜constriction 颈缩constructive interference 相长干涉contact angle 接触角contact area 接触面积contact force 接触力continuity equation 连续性方程continuous spectrum 连续光谱，连续谱continuous wave 连续波contract 收缩control experiment 对照实验，比对实验control grid 控制栅极control rod 控制棒control system 控制系统convection 对流converge 会聚converging lens 会聚透镜converging mirror 会聚镜convex 凸convex lens 凸透镜convex mirror 凸镜，凸面镜coolant 冷却剂cooling by evaporation 蒸发致冷cooling correction 冷却修正cooling curve 冷却曲线? cooling effect 冷却效应cooling system 冷却系统，散热系统coplanar forces 共面力core 心，核心Coriolis force 科里奥利力corkscrew rule 螺旋法则cornea 角膜corona discharge 电晕放电corpuscular theory of light 光的微粒学说correction 矫正，修正cosmic radiation 宇宙辐射coulomb 库伦Coulomb?s law 库伦定律count rate 计数率counter 计数器counter weight 平衡锤，配重couple 力偶coupled oscillation 耦合振荡coupling 耦合covalent bond 共价键crane magnet 起重磁铁creep 蠕变crest 波峰critical angle 临界角critical damping 临界阻尼critical mass 临界质量critical point 临界点critical temperature 临界温度critical velocity 临界速度crocodile clip 鳄鱼夹cross hairs 十字丝，叉丝cross-sectional area 截面积Crova?s disc 克罗瓦盘crystal 晶体crystal diffraction 晶体衍射，晶体绕射crystal lattice 晶体点阵，晶体格子，晶格crystal planes 晶面crystalline 结晶的crystallization 结晶crystallography 晶体学cubical expansivity 体积膨胀系数，体积膨胀率curie 居里current 电流current amplification 电流放大current amplification factor 电流放大因素current amplifier 电流放大器current balance 电流天平current density 电流密度current gain 电流增益current intensity 电流强度current pulse 电流脉冲current sensitivity 电流灵敏度current stabilizer 稳流器current transfer characteristic 电流转移特性current-carrying conductor 载电流导体current-voltage characteristic curve 电流—电压特性曲线? curved mirror 曲面镜cyclotron 回旋加速器cylindrical concave lens 柱面凹透镜cylindrical concave mirror 柱面凹镜cylindrical convex lens 柱面凸透镜cylindrical convex mirror 柱面凸镜cylindrical lens 柱面透镜cylindrical mirror 柱面镜D d.c. generator 直流发电机 d.c. motor 直流电动机Dalton?s law of partial pressures 道尔顿分压定律damped harmonic motion 阻尼谐动damped harmonic oscillation 阻尼谐振damped oscillation 阻尼振荡damping 阻尼damping force 阻尼力dark fringe 暗纹data 数据dating 年代测定daughter nucleus 子核daughter nuclide 子核素de Broglie relation 德布罗意关系式de Broglie wave 德布罗意波dead time 失效时间decade capacitance box 十进电容箱decade resistance box 十进电阻箱decay 衰变decay analogue 衰变模拟decay constant 衰变常数，衰变常量decay curve 衰变曲线? decay law衰变定律decay product 衰变产物decelerate 减速deceleration 减速度decibel 分贝decode 译码，解码decoder 译码器，译码器deflection 偏转deflection plate 偏转板deflection system 偏转系统deflection tube 偏转管deformation 形变degradation of energy 能量退降，能量递降degree 度degree Celsius 摄氏度degree of freedom 自由度demagnetization 去磁，退磁demonstration diode 演示用二极管demonstration meter 演示用电表density 密度depletion layer 耗尽层，阻挡层depth of field 景深derived quantity 导出量derived unit 导出单位destructive interference 相消干涉detection 探测detector 探测器detector of radiation 辐射探测器deuterium 氘，重氢deuteron 氘核，重氢核deviation 偏向，偏差device 装置，设计，器件diamagnetism 抗磁性diaphragm 光阑，膜片diatomic molecule 双原子分子dielectric 电介质，介电的dielectric constant 介电常数，介电常量，电容率dielectric polarization 电介质极化dielectric strength 电介质强度differential equation 微分方程differential input voltage 差动输入电压diffracted ray 衍射线，绕射线? diffraction 衍射，绕射diffraction grating 衍射光栅，绕射光栅diffuse reflection 漫反射diffusion 扩散，漫射diffusion cloud chamber 扩散云室digital 数字的digital display 数字显示digital signal 数字讯号digital-to-analogue conversion 数模转换dimension 量纲，因次，维，大小dimensional analysis 量纲分析，因次分析diminished 缩小diode 二极管diode probe 二极管微波探测器dioptre 屈光度，焦度dipole 偶极子direct current 直流电direction 方向，方位direction of propagation 传播方向directly heated cathode 直热式阴极discharge 放电disintegration 蜕变dislocation 位错dispersion 色散dispersive power 色散能力，色散本领，色散率displacement 位移，排量displacement can 排水罐displacement-time graph 位移—时间关系线图dissipative force 耗散力distance 距离distance-time graph 距离—时间关系线图distortion 失真，扭曲，畸变disturbance 干扰diverge 发散diverging lens 发散透镜diverging mirror 发散镜division of amplitude 振幅分割division of wavefront 波阵面分割，波前分割domain 畴，域domestic circuit 家居电路donor 给予体doped semiconductor 掺杂半导体doping 掺杂Doppler broadening 多普勒谱线增宽Doppler effect 多普勒效应Doppler shift 多普勒频移dosage 剂量dose 剂量dose rate 剂量率double pulley 双滑轮double refraction 双折射double slit 双缝double-pole-double-throw switch 双刀双掷开关doublet 双重线? drag force 阻力，曳力drift velocity 漂移速度driver circuit 驱动电路driver frequency 驱动频率driving cell 驱动电池driving force 驱动力driving mirror 行车后视镜dry battery 干电池组dry cell 干电池dual trace oscilloscope 双迹示波器ductile 延性的Dulong-Petit law 杜隆—珀替定律dynamic equilibrium 动态平衡dynamic friction 动摩擦dynamic resistance 动态电阻dynamics 动力学dynamo 发电机E earth 接地，地线? earthquake waves 地震波ebonite 硬橡胶，硬质胶ebonite rod 硬橡胶棒，硬质胶棒echo 回声，回波eddy current 涡电流，涡流eddy current damping 涡流阻尼eddy current loss 涡流损耗effective mass 有效质量efficiency 效率effort 施力Einstein?s mass-energy relation 爱因斯坦质能关系式elastic collision 弹性碰撞elastic constant 弹性常数，弹性常量elastic deformation 弹性形变elastic hysteresis 弹性滞后elastic limit 弹性极限elastic strain energy 弹性应变能elasticity 弹性electric bell 电铃electric charge 电荷electric current 电流electric field 电场electric field intensity 电场强度electric field pattern 电场图形electric fire 电暖炉electric line of force 电力线? electric motor 电动机electric potential 电势，电位electric power 电功率electric shock 电震electrical appliance 电器electrical conductivity 导电率electrical energy 电能electrical oscillation 电振荡electrical potential energy 电势能，电位能electrical resonance 电共振electricity 电，电学electrode 电极electrolysis 电解electrolyte 电解质electrolytic 电解质的，电解的electrolytic capacitor 电解质电容器electromagnet 电磁铁，电磁体electromagnetic coil 电磁感应圈electromagnetic contact 电磁触点electromagnetic force 电磁力electromagnetic induction 电磁感应electromagnetic moment 电磁矩electromagnetic oscillation 电磁振荡electromagnetic radiation 电磁辐射electromagnetic spectrum 电磁波谱electromagnetic wave 电磁波electromagnetism 电磁学electrometer 静电计electromotive force 电动势electron 电子electron beam 电子束electron cloud 电子云electron diffraction 电子衍射，电子绕射electron drift 电子漂移electron energy level 电子能级electron gun 电子枪electron transition 电子跃迁electron tube 电子管electron-volt 电子伏特，电子伏electronics 电子学electrophorus 起电盘electroscope 验电器electrostatic bond 静电键electrostatic field apparatus 静电场仪器electrostatic precipitation 静电沉淀法electrostatics 静电学element 元素，组件elliptic orbit 椭圆轨道elongation 伸长度emergent ray 出射线? emission 发射emission line 发射谱线? emission spectrum 发射光谱，发射谱emissivity 发射率，比辐射率emit 发射emitter 发射极，射极emitter current 发射极电流，射极电流enamelled wire 漆包线? encode 编码encoder 编码器end-correction 端部修正，管口校正量end-on collision 同向碰撞，尾追碰撞energetic particle 高能粒子energy 能量，能energy band 能带energy conversion 能量转换energy conversion efficiency 能量转换效率energy input 能量输入energy level 能级energy output 能量输出energy transfer 能量转移enriched uranium 浓缩铀equation of continuity 连续性方程equation of state 物态方程equation of uniformly accelerated motion 匀加速运动方程equatorial orbit 赤道轨道equilibrium 平衡equilibrium condition 平衡条件equilibrium spacing 平衡间距equipartition of energy 能量均分equipotential 等势的，等位的equipotential line 等势线，等位线? equipotential surface 等势面，等位面equivalent capacitance 等效电容equivalent inductance 等效电感equivalent resistance 等效电阻erect 正立escape velocity 逃逸速度ether 以太，醚evacuation 抽成真空evaporation 蒸发excess pressure 超压，逾电压excitation 激发excitation energy 激发能excitation potential 激发电势，激发电位excitation voltage 激发电压excited 受激excited energy level 受激能级excited state 受激态expansion 膨胀expansivity 膨胀系数，膨胀率exponential change 指数式改变exponential decay 指数式衰变exposure 曝光量，照射extension 伸长external force 外力external work 外功extra high tension 超高电压extra-nuclear structure 核外结构extraordinary ray 非常光线? extrapolation 外推，外推法extrinsic semiconductor 含杂质半导体eyepiece 接目镜，目镜F f-number f数，光圈数f-stop f制光圈far point 远点farad 法拉Faraday constant 法拉第常数，法拉第常量Faraday?s law of electromagnetic induction 法拉第电磁感应定律fast breeder reactor 快中子增殖反应堆feedback 反馈feedback amplifier 反馈放大器feedback resistance 反馈电阻ferromagnetic substance 铁磁性物质ferromagnetism 铁磁性fictitious force 假力，伪力fidelity 保真性，保真度field coil 场线圈field effect transistor 场效应晶体管field intensity 场强field lines 场力线? field magnet 场磁铁，场磁体field of view 视场，视野field strength 场强figure of merit 优值，灵敏值filament 灯丝，丝极filter capacitor 滤波电容器filter circuit 滤波电路filter pump 滤泵final state 终态，末态final velocity 末速度fine-adjustment 微调，细调fire alarm 火警警报器，火警钟first law of thermodynamics 热力学第一定律first order spectrum 第一级光谱，第一级谱fission 裂变fission reactor 裂变反应堆fixed point 定点fixed pulley 定滑轮fixed resistor 定值电阻器flat coil 扁平线圈flat solenoid 扁平螺线管flat-bottomed flask 平底烧瓶Fleming?s left hand rule 弗林明左手定则Fleming?s right hand rule 弗林明右手定则floating body 浮体fluid 流体fluid dynamics 流体动力学fluorescence 荧光fluorescent screen 荧光屏，荧光幕flux 通量flux density 通量密度fly-back 回扫flywheel 飞轮focal length 焦距focal plane 焦平面focus 焦点，聚焦，对焦focus control 聚焦控制follower circuit 跟随电路foot pump 脚踏泵force 力force constant 力常数，力常量force polygon 力多边形force resolution 力的分解force triangle 力三角形force-extension curve 施力—伸长关系曲线? forced oscillation 受迫振荡former 框forward biased 正向偏压forward current 正向电流fossil fuel 化石燃料Foucault?s rotating mirror method 傅科旋转镜法frame of reference 参考坐标系，参考系Franck-Hertz experiment 弗兰克—赫兹实验Fraunhofer diffraction 夫琅和费衍射，夫琅和费绕射Fraunhofer lines 夫琅和费谱线? free electron 自由电子free fall 自由下坠，自由下落free falling body 自由落体free oscillation 自由振荡free path 自由程free space 自由空间freeze 凝固freezing point 凝固点freon 氟利昂，二氯二氟甲烷frequency 频率frequency modulation 调频，频率调制frequency response 频率响应Fresnel diffraction 菲涅耳衍射，菲涅耳绕射Fresnel?s biprism 菲涅耳双棱镜friction 摩擦，摩擦力friction compensated 补偿摩擦作用frictionless motion 无摩擦运动fringe 条纹fringe pattern 条纹图形fuel rod 燃料棒fulcrum 支点full adder 全加法器full-scale deflection 满标偏转full-wave rectification 全波整流full-wave rectifier 全波整流器fundamental frequency 基频fundamental mode of vibration 基谐振动模式fundamental note 基音fundamental quantity 基本量fundamental unit 基本单位fuse 保险丝fuse rating 保险丝额定值fusion 熔解，聚变fusion point 熔点fusion reactor 聚变反应堆G G - clamp G-形钳gain 增益gain control 增益控制galaxy 星系Galilean telescope 伽利略望远镜Galileo?s thought experiment 伽利略假想实验galvanometer 电流计，检流计gamma radiation 伽玛辐射gamma ray 伽玛射线? gap 隙gas 气，气体gas pressure 气体强压，气压gaseous phase 气相gaseous state 气态gauge 规，计Gauss theorem 高斯定理Geiger counter 盖革计数器Geiger-Marsden scattering experiment 盖革—马斯登散射实验Geiger-Muller counter 盖革—弥勒计数器Geiger-Muller tube 盖革—弥勒管general gas equation 普适气体方程general gas law 普适气体定律generator 发电机genetic effect 遗传效应geometrical optics 几何光学germanium 锗ghost effect 迭影效应glancing angle 掠射角glass fibre 玻璃纤维glycerine 甘油gold foil 金箔fold leaf electroscope 金箔验电器gradient 斜率，梯度graduated cylinder 量筒Graham?s law of diffusion 格拉哈姆散定律grain 粒，晶粒gramophone record 唱片，唱碟graph 图，线图，图表graphical method 图解法grating 光栅grating spectrometer 光栅光谱仪，光栅分光计gravitational acceleration 重力加速度gravitational attraction 引力，重力gravitational constant 引力常数，引力常量gravitational field 引力场，重力场gravitational force 引力，重力gravitational mass 引力质量gravitational potential 引力势，重力势gravitational potential difference 引力势差，重力势差gravitational potential energy 引力势能，重力势能gravity 重力grazing incidence 掠入射，切入射greenhouse effect 温室效应grid 栅极grid control 栅极控制grid system 电力网groove 纹道，针槽，开槽ground 接地ground state 基态guinea and feather experiment 「硬币与羽毛」实验H hair spring 游丝half adder 半加法器half-life 半衰期half-silvered mirror 半镀银镜half-wave rectification 半波整流half-wave rectifier 半波整流器Hall effect 霍耳效应Hall probe 霍耳探测器Hall voltage 霍耳电压hand stroboscope 手动式频闪观测器harmonic 谐音harmonic motion 谐运动harmonic oscillation 谐振荡head-on collision 对正碰撞，正碰heat 热，热量，加热，热学heat absorbent 吸热剂heat absorber 吸热器heat absorption 吸热，热吸收heat capacity 热容量heat conduction 热传导heat exchange 热交换heat flow 热流heat gain 热增益，得热heat insulation 热绝缘，隔热heat loss 热损耗，失热heat proof 耐热的，隔热的heat pump 热泵heat radiation 热辐射heat reservoir 热库，储热器heat sink 热壑heat transfer 热传递，热转移heater 发热器，加热器heating effect 热效应heating element 发热组件Helmholtz coils 亥姆霍兹线圈henry 亨利，亨hertz 赫兹，赫high dispersion prism 高色散棱镜high tension 高电压hole 空穴，空子hollow plastic lens 空心塑料透镜hollow plastic prism 空心塑料棱镜hologram 全息图holography 全息术，全息学Hooke?s law 虎克定律horizontal 水平horizontal component 水平分量horizontal deflection 水平偏转horseshoe magnet 蹄形磁铁hot cathode 热阴极hour 小时Huygens? principle 惠更斯原理hydraulic press 水压机hydroelectric power 水力发电hydrogen bomb 氢弹hygrometer 湿度计hyperbolic orbit 双曲线轨道hypodermic needle 皮下注射针头hypodermic syringe 皮下注射针筒hypothesis 假说，假设hysteresis 滞后现象I ideal gas 理想气体ideal gas equation 理想气体方程ideal gas temperature scale 理想气体温标ideal machine 理想机械illuminate 照明，照亮image 像image distance 像距immerse 浸没immersion heater 浸没式电热器impact 碰撞impedance 阻抗impulse 冲量impurity 杂质in focus 焦点对准in parallel 并联in phase 同相in series 串联incident ray 入射线? incident wavefront 入射波阵面，入射波前inclined plane 斜面incoherent 不相干的incompressible fluid 非压缩性流体indicator 指示器indirectly heated cathode 旁热式阴极induced charge 感生电荷induced current 感生电流induced e.m.f. 感生电动势induced voltage 感生电压? inducing charge 施感电荷inducing current 施感电流inductance 电感inductance capacitance coupled circuit 感容耦合电路inductance coil 电感线圈induction 感应induction heating 感应生热inductive circuit 电感电路inductive component 电感性分量inductive reactance 感抗inductor 电感器，感应器inelastic collision 非弹性碰撞inert gas 惰性气体inertia 惯性，惯量inertia balance 惯性秤inertial frame 惯性坐标系，惯性系inertial mass 惯性质量infra-red detector 红外线探测器infra-red radiation 红外辐射infra-red ray 红外线? initial state 初态initial velocity 初速度input 输入input bias current 输入偏压电流input characteristic 输入特性input current 输入电流input offset current 输入补偿电流input power 输入功率input resistance 输入电阻input voltage 输入电压input-output voltage characteristic 输入—输出电压特性instantaneous acceleration 瞬时加速度instantaneous angular velocity 瞬时角速度instantaneous current 瞬时电流instantaneous power 瞬时功率instantaneous speed 瞬时速率instantaneous velocity 瞬时速度instantaneous voltage 瞬时电压insulation 绝缘insulator 绝缘体integrated circuit 集成电路intensity 强度intensity control 强度控制intensity of current 电流强度interaction 相互作用interatomic force 原子间力interatomic potential 原子间势，原子间位interatomic separation 原子间距intercept 截距，截段interconversion 互换interference 干涉interference pattern 干涉图形internal energy 内能internal force 内力internal resistance 内电阻internal work 内功international system of units 国际单位制，公制，十进制interval 间隔intrinsic semiconductor 纯半导体，本征半导体inverse-square law 平方反比定律inverted 倒立的inverter 反相器，倒换器inverting input 反相输入ion 离子ion-pair 离子偶，离子对ionic bond 离子键ionic structure 离子结构ionization 电离作用ionization chamber 电离室ionization current 电离电流ionization energy 电离能ionization potential 电离电势，电离电位ionization voltage 电离电压ionize 电离ionized atom 离子ionized layer 电离层ionizing power 致电离能力，致电离本领ionizing radiation 致电离辐射ionosphere 电离层iris 虹膜，可变光阑iron core 铁心iron filings 铁粉irreversible process 不可逆过程isobar 等压线，同质异序素isobaric expansion 等压膨胀isobaric process 等压过程isochronous oscillation 等时振荡isotherm 等温线? isothermal process 等温过程isotope 同位素isovolumetric process 等容过程J Jaegers method 耶格法jet propulsion 喷气推进jockey 滑动触头joule 焦耳joulemeter 焦耳计junction 连接，接头junction diode 面结型二极管junction transistor 面结型晶体管K Kaleidoscope 万花筒Kelvin 开尔文，开Kelvin temperature scale 开氏温标Kepler?s law 开普勒定律key 电键kilogram 千克kilowatt 千瓦特，千瓦kilowatt-hour 千瓦小时，千瓦时kilowatt-hour meter 电表，千瓦时计kinematics 运动学kinetic energy 动能kinetic friction 动摩擦kinetic theory 分子运动论kinetic theory model 分子运动模型kinetic theory of gases 气体分子运动论Kirchhoff?s law 基尔霍夫定律kit 套件knife-edge 刃形支承，刀刃，刀边kryton 氪Kundt?s tube 孔脱管L lagging 保温套laminar flow 层流laminated 分层的，迭片的laser 激光，激光器laser beam 激光束laser material 激光材料latch 闩锁latent heat 潜热lateral 横向，侧向，旁向lateral inversion 横向倒置lateral magnification 横向放大，横向放大率lateral search coil 横向探察线圈lattice 点阵，晶格lattice spacing 点阵间隔，点阵间距law 定律law of conservation of momentum 动量守恒定律law of reflection 反射定律law of refraction 折射定律lead 导线，铅lead-acid accumulator 铅酸蓄电池leakage current 漏泄电流least distance of distinct vision 最小明视距离Leclanche cell 勒克朗谢电池length 长度lens 透镜，晶体，晶状体lens formula 透镜公式lens holder 透镜座lens marker?s formula 透镜制造者公式Lenz?s law 楞次定律leukaemia 白血病lever 杠杆light 光，光学light beam 光束，光柱light dependent resistor 光敏电阻器light emitting diode 发光二极管light guide 光导light pipe 光导管light ray 光线? light sensitive resistor 光敏电阻器light source 光源lightning 闪电lightning conductor 避雷针limiting angle 极限角limiting friction 极限摩擦line of action 作用线? line of force 力线? line spectrum 线状光谱，线状谱linear air track 线性气垫导航linear electronics 线性电子学linear expansivity 线性膨胀系数，线性胀率linear flow 线流linear momentum 线动量linear voltage amplification 线性电压放大率linearly polarized wave 线偏振波liquefaction 液化liquid 液体liquid crystal 液晶体liquid phase 液相liquid pressure 液体压强liquid-in-glass thermometer 玻管液体温度计Lissajous figure 利萨如图形live 载电，活线，火线Lloyd?s mirror 洛埃镜load 负荷lodestone 磁石logic gate 逻辑门logic level 逻辑电平，逻辑级logic level indicator 逻辑电平指示器，逻辑级指示器logic value 逻辑值long sight 远视long wave 长波longitudinal magnification 纵向放大，纵向放大率longitudinal wave 纵波loop 回路，圈Lorentz force 洛兰兹力Lorentz rotating disc 洛兰兹旋转盘loudness 响度loudspeaker 扬声器low frequency a.c. generator 低频交流发电机low voltage 低电压low voltage immersion heater 低压浸没式电热器lower limit 下限lycopodium powder 石松粉Lyman series 赖曼系，赖曼光谱M Mach number 马赫数machine 机械macroscopic 宏观的magnadur magnet 玛格纳多尔磁铁magnet 磁铁，磁体magnet keeper 永久磁铁衔铁magnetic domain磁畴，磁域magnetic effect 磁效应magnetic field 磁场magnetic field board 磁场板magnetic field intensity 磁场强度magnetic field strength 磁场强度magnetic flux 磁通量magnetic flux density 磁通量密度magnetic flux linkage 磁链，磁键，磁通匝数magnetic force 磁力magnetic hysteresis 磁滞magnetic induction 磁感应强度，磁感应magnetic line of force 磁力线? magnetic material 磁性材料magnetic meridian 磁子午线? magnetic moment 磁矩magnetic north pole 磁北极magnetic permeability 磁导率magnetic pole 磁极magnetic screen 磁屏magnetic shield 磁屏magnetic south pole 磁南极magnetic susceptibility 磁化率magnetic tape 磁带magnetic tape recorder 磁带录音机magnetic torque 磁矩magnetic track 磁迹magnetism 磁学，磁性magnetization 起磁，磁化作用magnetize 磁化magnetizing current 磁化电流magnification 放大，放大率magnified 放大的magnifying glass 放大镜magnifying power 放大率magnitude 量，量值mains frequency 市电频率mains immersion heater 市电浸没式热器mains supply 市电电源majority carriers 多数载流子malleable 展性的，韧性的Maltese cross tube 马尔塔十字管manometer 流体压强计mass 质量mass defect 质量亏损mass number 质量数mass spectrometer 质谱仪mass-energy relation 质能关系matter wave 物质波maximum error 最大误差mean free path 平均自由程measurement 测量mechanical advantage 机械利益mechanical efficiency 机械效率mechanical energy 机械能mechanical oscillation 机械振荡mechanical wave 机械波mechanism 机制，机理medium 介质medium wave 中波Melde?s experiment 迈尔德实验melt 熔化melting point 熔点meniscus 弯液面，弯月面meniscus lens 凹凸透镜，弯月形透镜mercury 汞，水银metal fatigue 金属疲劳fetal grid 金属珊metallic bond 金属键metastable 亚稳态的，介稳态的method of dimensions 维量法，因次法method of no-parallax 无视差法metre 米metre bridge 滑线电桥，米尺电桥metre rule 米尺mica 云母mica capacitor 云母电容器microammeter 微安培计，微安计microelectronics 微电子学micrometer 测微计micrometer screw gauge 螺旋测微计microphone 微音器，传声器microscope 显微镜microscopic 微观的microwave 微波microwave apparatus 微波仪器microwave receiver 微波接收器microwave transmitter 微波发送器milliammeter 毫安计，毫安计Millikan experiment 密立根实验millimetre 毫米minimum deviation 最小偏向minority carrier 少数载流子minute 分，分钟mirage 海市蜃楼，蜃景mirror 镜mirror formula 球面镜公式mobility 动性，迁移率mode 模式model eye 眼球模型model power line 输电线模型moderator 减速剂，缓和剂modulation 调制，调节module 组件modulus of elasticity 弹性模量modulus of rigidity 刚性模量molar gas constant 摩尔气体常数，摩尔气体常量molar heat capacity 摩尔热容量molar volume 摩尔体积mole 摩尔molecular bombardment 分子撞击molecular force 分子力molecular motion 分子运动molecular polarization 分子极化molecular separation 分子间距molecular structure 分子结构molecule 分子moment 矩moment arm 矩臂，力臂moment of couple 力偶矩moment of dipole 偶极矩moment of force 力矩moment of inertia 转动惯量moment of momentum 动量矩momentum 动量monatomic molecule 单原子分子monochromatic light 单色光motion 运动motor 电动机motor rule 电动机法则movable pulley 动滑轮moving-coil galvanometer 动圈式电流计，动圈式检流计moving-coil loudspeaker 动圈式扬声器moving-coil meter 动圈式电表multiflash photography 多闪照相法multimeter 万用电表，多用电表multiple image 复像multiple reflection 多次反射multiplication process 倍增过程multiplier 倍加器multivibrator 多谐振荡器musical instrument 乐器mutation 突变multiple-slit interference 多缝干涉mutual inductance 互感mutual induction 互感应mutually perpendicular 互相垂直的。

MAT 测试系统介绍

L_line In R_line In Driver out
Fixture / / / /
Combo connector
Busy LED
Line LED
Communicating with System
System connected to PC
PC Line In USB host Line Out L Line Out R
Flicker noise
THD+N=THD+noise
Random noise
IBD=In band Distortion
Too small distance
All band noise Flicker noise
6
Determine digital parameter to measurement noise
So it is necessary to develop a test system to capture speaker noise failure at flip level
3
Challenge to take up:
How to define the failure
Audio Noise is a subjective feeling of audio signal. Any differences between original signal and actual heard sound can be recognized as noise. But some of them are acceptable, some are not. It’s not directly corresponding to certain measurable physical parameter.

Chapter6 Power Spectrum

1 maximum at ω = 0, and has a width δω ∼ T , but with oscillating tails falling − 1 ˜ (ω, 2π ) on a pure frequency ωs off only as ω . Figure 6.1 shows the effect of H T π that is not an exact multiple of 2T , so does not “ﬁt” with the measurement period T . The line shows the functional form of the convolution in the [] in (6.5) for ˜ (ω − ωs ) , and the points show the values at the discrete y(ω) ˜ = δ(ω − ωs ) i.e. H π frequencies n × 2T . Note that the oscillations do not show up because the same 2π scale T determines the oscillations and the discrete frequencies. (The values used π in this plot are ωs = .126π , T = 8 so that 2T = π = 0.25 so that the 8 , and “Nyquist frequency” π/ is 4π .) So we are told in (6.5) to “take the ideal Fourier transform y(ω) ˜ , convolve π ˜ (broaden) it with the resolution function H , sample the result at ω = integer × 2T and then superimpose the result repeatedly displaced by ω = integer × 2π ”. The last step means that we can restrict the range of ω to the Nyquist range − π < ω ≤ π since other ranges are just duplications of this range, and that amplitudes

Spectral Density of Sample Covariance Matrices of Colored Noise

n n j xi k xk = k=1 k=1 i j Xk Xk = k=1 n i j Xk Xk or c = xxT = XX ∗ = X X T ,
ci,j =
(6)
where the rows of the matrices X and X are the transformed rows of the matrix x. Colored noise is a random signal with a non-ﬂat power spectrum. We are interested in the question how the proﬁle of the power spectrum inﬂuence the spectral density of the sample covariance matrix. In what follows we assume that the data matrix x has independent rows with identical power spectra and zero mean. Then the elements of the matrix X are also of mean zero - see the deﬁnition (6). Moreover the elements in the rows of the matrix x are independent. The transform X leads therefore also to a matrix with independent rows. Since the signal phase is random we get
Spectral Density of Sample Covariance Matrices of Colored Noise

诗和远方总有一个在路上英语作文

诗和远方总有一个在路上英语作文英文回答：In the realm of human existence, the symphony of life often reverberates between the allure of the present and the beckoning of the future. While some souls yearn for the tangible delights of the here and now, others are captivated by the siren call of distant shores. In this enduring dichotomy, the adage "poetry and the distance are always on the road" encapsulates the eternal dance between the familiar and the unknown.To quench our thirst for the immediacy of experience, we seek solace in the verses of poetry. Its words paint vibrant tapestries upon the canvas of our minds, evoking emotions that span the spectrum of human sentiment. The rhythm of its lines dances in harmony with our heartbeat, creating a visceral connection that anchors us to the present moment. In the realm of the physical, we succumb to the allure of tangible pleasures. The warmth of a lovedone's embrace, the taste of a gourmet delicacy, the exhilaration of a breathtaking sunset—these experiences ground us in the present, providing a respite from the relentless currents of time.Yet, even as we revel in the joys of the here and now, a subtle longing whispers within us—the yearning for something more. It is in this moment that the call of the distance becomes irresistible. The allure of uncharted territories, the promise of new adventures, and the tantalizing glimpse of a future filled with infinite possibilities draw us inexorably forward. We embark on quests that lead us to distant lands, expose us to unfamiliar cultures, and challenge our preconceptions. In the process, we discover not only the world but also ourselves.The journey to the distance is often fraught with uncertainty and hardship. The path may be arduous, the destination elusive. Yet, it is precisely these challenges that forge our character and shape our destiny. Through the trials we endure, we gain resilience and wisdom. We learnto adapt to the ever-changing landscape of life and to embrace the unknown with a sense of wonder.The pursuit of poetry and the distance is not a dichotomy but rather a complementary dance. Each nourishes and enriches the other, creating a symphony that resonates throughout our lives. While poetry grounds us in the present, the distance propels us toward the future. By embracing both, we live a life that is both grounded and aspirational—a life that is filled with both the pleasures of the here and now and the promise of endless possibilities.中文回答：在人生的河流中，我们总在诗歌和远方之间徘徊。

低头呈现不同的精神面貌和人生状态英语作文

低头呈现不同的精神面貌和人生状态英语作文全文共3篇示例，供读者参考篇1Keeping One's Head Down: A Window into the SoulWhen was the last time you really looked at someone with their head down? I'm not talking about a quick glance as you rushed past them on the street. I mean truly studied their face, their posture, the angle of their bent neck. If you slow down and observe, you'll find that the simple act of keeping one's head down can reveal so much about a person's inner state and outer circumstances. It's an ingrained instinct that arises from our deepest thoughts, feelings, and life situations. Let me illustrate what I mean with some examples:The Shy IntrovertThere's a quiet girl in my chemistry class who always keeps her head down low. Her chin practically rests on her chest as she hunches over her desk, hiding behind a curtain of long, dark hair. You'd hardly notice her if she didn't sit in the front row. When called on, she responds in a voice so faint you can barely hear it. Her head remains dutifully lowered even as she speaks. Thismeek posture is the physical manifestation of her shyness and discomfort with being the center of attention. By making herself as small and invisible as possible, she hopes to avoid the scrutiny and judgment she fears from others. Her downcast eyes are like blinders, blocking out the critical gazes she imagines all around her. For the extremely shy, keeping one's head down is an attempt at solitude even in a crowd.The Sullen RebelAt the opposite end of the spectrum, there's the sullen rebel whose bent head broadcasts their disdain and rejection of societal expectations. You know the type - face obscured by long bangs, eyes glowering up defiantly from under furrowed brows. This is the posture of the brooding misanthrope who wants you to see their scorn for all you represent. By keeping their head down, they're symbolically turning away from the world, disconnecting themselves from the herd in an act of resistant non-conformity. It's an outward projection of their inner alienation and rejection of your values. The downward tilt signals smoldering resentment and disillusionment. Simply put, they can't be bothered to face a world they despise.The Weary WorkhorseThen there's the willful downturn of the weary workhorse for whom keeping one's head down represents determination and perseverance. This is the posture of the overstressed student surrounded by towering stacks of books, crouched over a laptop until the wee hours completing one Herculean task after another. Their bent neck and slumped shoulders aren't cowering - they're bearing the weight of their many burdens. The downcast eyes aren't avoiding anything; they're focused with laserlike intensity on the problem at hand. When your responsibilities feel endless, you keep your head down and plow through with grim resilience. It's the physical embodiment of hard work and the refusal to be deterred by fatigue. For these diligent plodders, keeping one's head down is a declaration that the job will get done, no matter how daunting.The Browbeaten UnderdogIn stark contrast, sometimes a down-turned head signals meekness and resignation rather than diligence. This is the posture of the browbeaten underdog who has given up fighting and accepted a lesser place in society's hierarchies. It's the look of the marginalized facing systemic oppression - thepoverty-stricken street vendor, the undocumented immigrant laborer, the indigenous person in the majority culture. Theirhung head isn't one of purpose like the workhorse, but of defeated subjugation after being stamped down by those in power. The downcast eyes study the ground not in concentration but in fear of retaliation for defiance. Keeping one's head down is a defense mechanism, a plea not to be noticed and further abused. It's the physical actualization of hopelessness and defeat.The Pious WorshiperIn religious contexts, the hanging of one's head can take on still other meanings. For the pious worshiper, it's an expression of humble reverence before the divine. By inclining one's neck, you're symbolically lowering yourself in a gesture of submission and obedience to God's supremacy. Keeping your head up would be a prideful act, so the bowed head signals deference and meekness. In prayer you're meant to look down at the floor, not impiously up at the heavens. That bent neck is an embodiment of the spiritual self-abnegation and surrender of the ego required of the faithful. For the truly devout, keeping one's head respectfully down is a profound recognition of your insignificance before the glory of the Almighty.So you see, the simple motion of directing one's gaze toward the ground can outwardly manifest our deepest innerstates - from pride to penance, resolution to resignation. That humble hanging of the head belies the whole spectrum of the human condition simmering beneath. The next time you see someone bent at an angle, pause and consider what unspoken circumstances might be weighing on their neck and casting their vision downward. You may just catch a glimpse into the hidden emotional terrain of their soul.篇2Lowering One's Head: A Window into the SoulHave you ever noticed how much can be conveyed by the simple act of lowering one's head? It's a gesture so commonplace that we often overlook its deeper significance. But if you pay close attention, you'll find that the way someone lowers their head can reveal volumes about their inner mental state and life circumstances.As a student, I've had ample opportunity to observe this phenomenon among my peers. In the classroom, during a challenging exam, you'll see some students with their heads bowed low, brows furrowed in intense concentration. Their downcast gaze is a symbol of their unwavering focus, their determination to conquer the task at hand. It's a reminder thattrue academic success often requires shutting out external distractions and immersing oneself fully in the pursuit of knowledge.On the other hand, there are those whose heads hang low not out of concentration, but out of a sense of defeat or despair. Perhaps they've struggled to grasp a particular concept, or they've faced a series of setbacks that have chipped away at their confidence. Their slumped posture and averted gaze seem to cry out, "I'm not good enough. I can't do this." In these moments, it's crucial for us as classmates to offer a supportive word or a reassuring smile – a reminder that every challenge is surmountable with perseverance and the right mindset.But the stories told by lowered heads extend far beyond the classroom walls. On the bustling city streets, you'll encounter individuals whose heads are bowed not by choice, but by circumstance. The homeless man huddled on the sidewalk, his face obscured by a tattered baseball cap, is a poignant example. His downcast eyes speak of a life lived on the fringes of society, a daily struggle for survival that most of us can scarcely comprehend. In that moment, a simple act of acknowledgment –a nod, a smile, or the offer of a few coins – can remind him that he is seen, that he matters.Then there are those whose bowed heads are a mark of humility, not dejection. The monk in silent meditation, the artist lost in the throes of creation, the scientist hunched over a microscope – each of them exhibits a posture of reverence and awe before the mysteries of existence. Their lowered gaze is a sign of respect, a recognition that there are forces and truths greater than any individual can fully comprehend.And who could forget the lover's shy glance, the coy lowering of eyes that betrays a flutter of the heart? In these moments, a bowed head can signify not sadness or humility, but the delicate dance of attraction, the vulnerability of opening oneself to the possibility of connection.As I navigate the twists and turns of my own life journey, I've come to appreciate the profound insights that can be gleaned from this simple gesture. When I catch myself with my head bowed low, I pause to reflect on the emotional undercurrents at play. Am I feeling overwhelmed by the weight of academic pressures? Or perhaps I'm wrestling with a personal challenge, grappling with self-doubt or insecurity?In these moments of introspection, I've learned to embrace the power of lifting my chin, of meeting the world with a steady gaze. It's a conscious act of reclaiming my sense of self-worth, ofreminding myself that I am capable and deserving of success, no matter the obstacles that may lie ahead.And yet, there are times when lowering my head is not a sign of weakness, but of humility and gratitude. When I find myself in awe of the natural world's majesty or moved by a act of kindness, bowing my head is a way to honor those moments of transcendence, to ground myself in a sense of reverence and interconnectedness.In the end, the simple act of lowering one's head is a powerful reminder that we are all united by our shared humanity. Behind every bowed head lies a complex tapestry of emotions, experiences, and life circumstances – a story waiting to be told, understood, and embraced with empathy and compassion.As I continue on my academic and personal journey, I carry with me this newfound appreciation for the depths that can be revealed by a lowered head. It's a lesson in mindfulness, a reminder to look beyond the surface and seek to understand the rich inner lives of those around me.For in that simple act of bowing one's head, we glimpse not just a physical gesture, but a profound truth: that we are all fellow travelers on this journey called life, each of us navigatingour own unique paths, our own triumphs and struggles, our own moments of joy and sorrow.And perhaps, by opening our eyes and our hearts to the stories told by lowered heads, we can find the courage to lift each other up, to offer a hand of support or a word of encouragement when it's needed most. In doing so, we create a world where no one has to walk alone, where every bowed head is met with compassion and every lifted gaze is greeted with a smile of understanding.篇3Bowing One's Head Presents Different Mental States and Life SituationsAs a student, I have come to realize that the simple act of bowing one's head can reveal a multitude of emotions, mindsets, and life circumstances. It's a subtle gesture that carries profound weight, communicating volumes without uttering a single word. Through keen observation and personal experience, I've learned to decipher the various nuances hidden within this seemingly innocuous movement.Let's begin with the most obvious scenario – bowing one's head in reverence or respect. This is a common sight in places ofworship, formal ceremonies, or when encountering figures of authority. It's a physical manifestation of humility, acknowledging a higher power or a position of deference. The weight of the bow, the duration it's held, and the accompanying body language all convey the depth of reverence. I've witnessed classmates bow their heads during school assemblies, their faces solemn and their shoulders slightly hunched, paying homage to the ideals and traditions we uphold.However, a bowed head can also signify a very different state of mind – one of dejection or disappointment. Imagine a student receiving their exam results, their head instinctively dropping as they confront the harsh reality of a poor grade. It's a visceral reaction to a setback, a momentary surrender to the weight of failure. I've seen my peers in this position, their shoulders slumped, their eyes downcast, as if the world had momentarily lost its luster. In these instances, the bowed head becomes a shield, a way to retreat inward and process the disappointment before mustering the strength to move forward.Yet, the act of bowing one's head can also be a sign of deep contemplation or introspection. Have you ever observed a classmate lost in thought during a lecture, their chin resting on their hand, their gaze fixed downward? This posture suggests atemporary detachment from the external world, a journey inward to grapple with complex ideas or wrestle with personal dilemmas. It's a moment of quiet reflection, a pause in the chaos of daily life to gather one's thoughts and find clarity. I've often found myself in this position, allowing my mind to wander and explore the depths of a concept or conundrum.On the other hand, a bowed head can be a manifestation of fatigue or exhaustion. After a grueling day of classes, assignments, and extracurricular activities, it's not uncommon to see students slouched over their desks, their heads drooping as they battle against the allure of sleep. This physical posture is a testament to the demands we face, the relentless grind that can sometimes overwhelm even the most dedicated among us. In these moments, the bowed head becomes a temporary surrender, a fleeting respite from the unrelenting pressures of academic life.But what about those rare instances when a bowed head is accompanied by a subtle smile or a twinkle in the eye? This is a sign of humility, of acknowledging one's accomplishments without succumbing to arrogance or pride. It's a graceful acceptance of praise or recognition, a quiet acknowledgment of hard work and perseverance. I've witnessed this in classmateswho have achieved remarkable feats, their heads gently dipping as they receive accolades, their faces radiating a mix of joy and humility.Conversely, a bowed head can also signify a sense of shame or regret. Perhaps a student has made a mistake, transgressed against the rules, or behaved in a manner unbecoming of their values. In these instances, the bowed head becomes a physical manifestation of remorse, a nonverbal apology for the misstep. It's a way of acknowledging one's wrongdoing and accepting the consequences, a silent plea for understanding and forgiveness.Interestingly, a bowed head can even be a sign of concentration or intense focus. Have you ever observed a classmate hunched over their desk, their head lowered as they pour over a complicated problem set or meticulously craft an essay? This posture is a testament to their dedication, their unwavering commitment to the task at hand. It's a way of shutting out external distractions and channeling every ounce of mental energy into the challenge before them.Lastly, let's not forget the bowed head as a gesture of prayer or spiritual contemplation. Whether in a place of worship or in the solitude of one's own thoughts, the act of bowing one's head can be a powerful connection to something greater thanourselves. It's a moment of vulnerability, of casting aside the burdens of the world and seeking solace or guidance from a higher power. I've witnessed this during moments of personal struggle, when the weight of life's challenges becomes too heavy to bear alone.In retrospect, it's remarkable how such a simple act – bowing one's head – can convey a multitude of emotions, mindsets, and life situations. It's a universal language that transcends words, a subtle yet profound expression of the human condition. As students, we navigate a tapestry of experiences, triumphs, and tribulations, and the way we carry our heads often serves as a mirror, reflecting our innermost thoughts and struggles.So, the next time you find yourself bowing your head, pause for a moment and consider the weight of that gesture. Are you surrendering to disappointment or embracing humility? Are you seeking solace in introspection or channeling your focus? Whatever the reason, remember that this simple act is a testament to the depth and complexity of the human experience, a nonverbal expression of the myriad emotions and circumstances that shape our journeys.In a world that often values bombast and bravado, the bowed head serves as a gentle reminder of the quiet strengththat lies within each of us. It's a poignant acknowledgment of our vulnerabilities, our struggles, and our triumphs – a physical manifestation of the rich tapestry that is the human condition.。

坚强的意志力英语作文

坚强的意志力英语作文Unwavering Willpower: The Key to Achieving Your Dreams。

Resilience, determination, and an unbreakable spirit –these are the hallmarks of those who have conquered the greatest challenges life has to offer. In a world thatoften seems to conspire against our dreams, it is the power of our own willpower that can propel us forward, guiding us through the storms of adversity and toward the shores of success.At the heart of every great achievement lies an individual whose resolve was forged in the crucible of hardship and self-doubt. Whether it is scaling the heightsof a towering mountain, launching a groundbreaking business, or overcoming a debilitating illness, the common threadthat binds these accomplishments is the unwaveringwillpower of the individuals who dared to dream and refused to surrender.Consider the story of Amelia Earhart, the pioneering aviator who shattered gender barriers and captivated the world with her daring feats. Despite facing countless obstacles and naysayers who doubted her abilities,Earhart's unwavering determination propelled her to become the first woman to fly solo across the Atlantic Ocean. Her journey was not without its setbacks and challenges, but her indomitable spirit refused to be extinguished, and she continued to push the boundaries of what was thought possible.Or take the example of Nelson Mandela, the iconic leader who spent decades imprisoned for his fight against apartheid. During his long years of incarceration,Mandela's willpower never wavered; his commitment tojustice and equality remained unshakable, and he emerged from his ordeal with an even stronger resolve to transform his country and the world.These are just a few of the countless individuals who have demonstrated the power of unwavering willpower. But what is it that sets these extraordinary people apart? Whatis the secret to their success, and how can we cultivate this same level of determination within ourselves?At the core of unwavering willpower is a deep-seated belief in oneself and one's ability to overcome any obstacle. It is a steadfast conviction that no matter how daunting the challenge may be, success is not only possible but inevitable. This unwavering self-belief is the foundation upon which all great achievements are built, and it is a quality that can be nurtured and developed through a combination of mindset, discipline, and perseverance.One of the key aspects of cultivating unwavering willpower is the ability to maintain a positive and focused mindset. It is all too easy to become bogged down by negative thoughts, self-doubt, and the fear of failure. But those who possess true willpower have learned to reframe their perspective, to see challenges not as obstacles but as opportunities for growth and learning.They understand that setbacks and failures are an inevitable part of the journey, and they approach them notwith trepidation but with a sense of curiosity and resilience. Instead of dwelling on what went wrong, they ask themselves, "What can I learn from this experience?" and "How can I use this as a stepping stone to greater success?"This ability to maintain a positive and solutions-oriented mindset is crucial, as it allows individuals to stay focused on their goals and to persist even in the face of adversity. It is a skill that can be developed through practices such as meditation, affirmations, and visualization, all of which can help to strengthen the neural pathways in the brain that are associated with resilience and determination.But unwavering willpower is not just a matter of mindset; it also requires a deep level of discipline and commitment. Those who have achieved great things have often done so through a relentless dedication to their craft, a willingness to put in the hard work and long hours necessary to hone their skills and push the boundaries of what is possible.Whether it is an athlete training for the Olympics, an entrepreneur building a startup from the ground up, or a student preparing for a challenging exam, the common thread is a willingness to make sacrifices, to push through the pain and discomfort, and to remain steadfast in the pursuit of their goals.This level of discipline is not easy to cultivate, and it often requires a significant amount of self-reflection and introspection. Individuals who possess unwavering willpower have learned to identify their weaknesses and blind spots, and they have developed strategies for overcoming them. They may set ambitious goals, break them down into smaller, more manageable steps, and hold themselves accountable to a rigorous schedule of practice and progress.But perhaps the most important aspect of unwavering willpower is the ability to persevere in the face of setbacks and failures. Those who have achieved great things have often done so through a willingness to dust themselvesoff, learn from their mistakes, and try again with renewed vigor and determination.They understand that success is not a straight line, but a winding path filled with twists and turns, and they are prepared to navigate those challenges with a steadfast resolve. They may encounter obstacles that seem insurmountable, but they refuse to be deterred, drawing strength from their inner reserves of courage and resilience.Ultimately, the power of unwavering willpower lies in its ability to transform the impossible into the possible. It is the driving force that propels individuals to reach new heights, to shatter the boundaries of what is thought to be achievable, and to leave an indelible mark on the world.Whether you are striving to achieve a personal goal, overcome a daunting challenge, or make a lasting impact on your community, the key to success lies in cultivating an unwavering sense of willpower. It is a journey thatrequires dedication, discipline, and a deep belief in oneself, but the rewards are truly limitless.So, embrace your inner strength, harness the power of your willpower, and let it guide you toward the realization of your dreams. For in the end, it is not the obstacles we face, but the determination with which we confront them, that truly defines the measure of our success.。

闪光的他们作文结尾摘抄

闪光的他们作文结尾摘抄英文回答：In the tapestry of life, moments of brillianceilluminate our path, guiding us toward a future filled with purpose and meaning. Like the ephemeral sparks of a firefly, these moments ignite a flame within our souls, forever shaping our destiny. They are the catalysts for transformation, the beacons that lead us toward our truest selves.As we navigate the complexities of existence, it is in these fleeting instances of brilliance that we discover our potential. They are harbingers of hope, reminding us that even in the darkest of times, there is always a glimmer of light to guide our way. These moments empower us to embrace challenges, to step outside of our comfort zones, and to strive for greatness.The brilliance of these experiences lies not only intheir transformative power but also in their ability to connect us to something greater than ourselves. Whether itis a profound conversation, a breathtaking artwork, or anact of kindness, these moments have the capacity to transcend the boundaries of time and space, forging an unbreakable bond between us.In the words of the renowned poet Walt Whitman, "The greatest height and sublimity does not stand in being ableto do, but in being." It is through these moments of brilliance that we truly come alive, experiencing the full spectrum of human emotions and the infinite possibilities that life has to offer.中文回答：人生犹如一幅织锦，闪光的瞬间点亮了我们的道路，指引我们走向一个充满意义和目标的未来。

英语作文我的心愿科学家

英语作文我的心愿科学家英文回答：My heart yearns to unravel the mysteries of the universe, to contribute to the advancement of human knowledge, and to leave an enduring legacy in the annals of science. As an aspiring scientist, I envision a future where my research and discoveries positively impact society and propel humanity toward a brighter tomorrow.Driven by an unquenchable thirst for understanding, I immerse myself in the intricacies of scientific inquiry. From the subatomic realm to the vastness of space, I seek to decipher the fundamental principles that govern our existence. Through experimentation, observation, and rigorous analysis, I aim to unlock secrets that have long eluded humankind.My scientific endeavors encompass a broad spectrum of disciplines, including but not limited to astrophysics,quantum physics, and biotechnology. I am particularly captivated by the cosmos, eager to explore the origins and evolution of the universe and to search for signs of extraterrestrial life. The quest for knowledge knows no bounds, and I am determined to push the frontiers of human understanding as far as my intellect will allow.Beyond the pursuit of pure knowledge, I am deeply committed to the practical applications of scientific discovery. I believe that science has the power to solve some of the world's most pressing challenges, from climate change to disease eradication. By harnessing the power of innovation and collaboration, I aspire to develop technologies and treatments that improve the lives of countless individuals.In addition to my research endeavors, I am equally passionate about inspiring future generations of scientists.I believe that every young mind has the potential to contribute to the advancement of science and that it is my responsibility to foster their curiosity and nurture their aspirations. Through mentorship and outreach programs, Iaim to ignite a love of science in young hearts and toequip them with the tools they need to become thescientists of tomorrow.My heart's desire is to leave an enduring mark on the world through my scientific contributions. I envision a future where my discoveries have led to advancements in medicine, space exploration, and our understanding of the universe. I hope to inspire countless others to pursuetheir passions in science and to make their own unique contributions to the betterment of humankind.中文回答：我的心愿是成为一名科学家，揭开宇宙的奥秘，为人类知识的进步做出贡献，并在科学史上留下持久的遗产。

The Power of Dreams and Goal Setting

The Power of Dreams and Goal Setting Dreams and goal setting are essential aspects of human life. They give us a sense of direction, purpose, and motivation to strive for something better. The power of dreams lies in their ability to inspire and drive individuals to achieve their full potential. Setting goals, on the other hand, provides a roadmap for turning dreams into reality. Together, they form a powerful combination that can lead to personal growth and success.From a personal perspective, dreams have always played a significant role in shaping my life. As a child, I dreamt of becoming a successful writer, and that dream has been a driving force behind my actions and decisions. It has pushed me to pursue a degree in literature, to hone my writing skills, and to constantly seek opportunities to share my work with others. Without this dream, I might have settled for a different career path and missed out on the fulfillment that comes from pursuing my passion.Setting specific, achievable goals has been crucial in turning my dream into a reality. Instead of simply wishing to become a writer, I set goals such as completing a novel, getting published in a reputable magazine, and building a strong online presence. Each goal served as a milestone that brought me closer to my ultimate dream. By breaking down my aspirations into smaller, manageable tasks, I was able to make steady progress and stay motivated along the way.On a broader scale, dreams and goal setting have the power to drive societal progress and innovation. Many of the world's greatest achievements have stemmed from ambitious dreams and the determination to pursue them through goal setting. From space exploration to medical advancements, the power of dreams has led to groundbreaking discoveries and advancements that have transformed the way we live.However, it is important to acknowledge that not all dreams are easily attainable, and not all goals are within reach. Economic, social, and personal barriers can hinder individuals from pursuing their dreams and setting meaningful goals. For example, someone from a disadvantaged background may struggle to access the resources and opportunities neededto fulfill their aspirations. In such cases, the power of dreams and goal setting may seem out of reach, leading to feelings of frustration and disillusionment.Despite these challenges, it is crucial to remember that the act of dreaming itself can be a source of hope and resilience. Even in the face of adversity, holding onto a dream can provide the strength and determination to overcome obstacles. By setting realistic and adaptable goals, individuals can find ways to navigate around barriers and make progress towards their dreams, no matter how small the steps may seem.Moreover, the power of dreams and goal setting extends beyond individual aspirations to encompass collective endeavors. In the realm of business and organizations, having a shared vision and setting strategic goals can align teams and drive them towards success. When everyone is working towards a common dream, the collective effort becomes greater than the sum of its parts, leading to remarkable achievements and growth.In conclusion, the power of dreams and goal setting cannot be overstated. From personal ambitions to societal progress, they play a pivotal role in driving individuals and communities towards a brighter future. By nurturing our dreams and setting meaningful goals, we can unlock our full potential and make a positive impact on the world around us. As the saying goes, \"A dream becomes a goal when action is taken toward its achievement.\" So, let us continue to dream big and set goals that propel us forward, one step at a time.。

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Steps toward the power spectrum of matter. I. The mean spectrum of galaxies
J. Einasto 1 , M. Einasto1 , E. Tago1 , A. A. Starobinsky2 , F. Atrio-Barandela3 , V. M¨ uller4 , A. Knebe4 , P. Frisch5 , R. Cen6 , H. Andernach7 and D. Tucker8
1 2 3 4 5 6 7 8
Tartu Observatory, EE-2444 T˜ oravere, Estonia Landau Institute for Theoretical Physics, Moscow 117334, Russia F´ ısica Te´ orica, Universidad de Salamanca, 37008 Spain Astrophysical Institute Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany G¨ ottingen University Observatory, Geismarlandstr. 11, D-37083 G¨ ottingen, Germany Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA Depto. de Astronom´ ıa, IFUG, Apdo. Postal 144, C.P. 36000 Guanajuato, Gto., Mexico Fermilab, MS 127, Box 500, Batavia, IL 60510, USA
–2– Subject headings: cosmology: large-scale structure of the universe – cosmology: observations – galaxies: formation
ቤተ መጻሕፍቲ ባይዱ3– 1. Introduction
The power spectrum of matter is one of the most important statistics to describe the large-scale structure of the Universe. If the distribution of density inhomogeneities is Gaussian then the power spectrum characterizes the distribution of matter (in a statistical sense) completely. During the last decade considerable eﬀorts have been devoted to determining this function empirically from the distribution of galaxies and clusters of galaxies. These studies have shown that on small scales the power spectrum in real space can be satisfactorily expressed by a power law with an index somewhere between −2 and −1.5. On larger scales the spectrum turns over reaching a maximum on scales of 100 – 150 h−1 Mpc (we use a Hubble constant of 100 h km s−1 Mpc−1 ). The exact location of the maximum, its amplitude and shape are not well determined yet. The deep pencil-beam redshift survey of Broadhurst et al. (1990) indicates the presence of a sharp spike at a scale of l = 128 h−1 Mpc or wavenumber k = 2π/l = 0.05 h Mpc−1 . Power spectra of Abell-ACO clusters of galaxies (Einasto et al. 1997a, hereafter E97a, Retzlaﬀ et al. 1998, hereafter R98), and APM clusters (Tadros et al. 1998, T98) also indicate a rapid turnover from a spectrum with negative slope on galactic scales to a spectrum with positive slope; the turnover occurs at a high amplitude on a scale similar to the scale of the spike found by Broadhurst et al. . But not all power spectra obtained from galaxy surveys support this picture. Some data show a much ﬂatter spectrum near the maximum: the 3-D spectrum analysis of the Las Campanas Redshift Survey (LCRS; Lin et al. 1996, hereafter LCRS3d), and the IRAS surveys discussed by Tadros and Efstathiou (1995, hereafter TE95). Our main goal is to determine the mean matter power spectrum using all available data. This will be done in three steps. First, we derive the mean power spectrum of galaxies that best agrees with available observations and determine its main parameters (present Paper). By “the mean power spectrum of galaxies” we understand the spectrum of a population which includes all galaxies in real space in a large volume (fair sample). Second, we investigate the biasing phenomenon and develop a method to reduce the galaxy power spectrum to matter (Einasto et al. 1999a, Paper II). The method is based on the assumption that the structure evolution in the Universe is due to gravity; in this case galaxy formation is essentially a threshold process. We ﬁnd a relation between the biasing parameter and the fraction of mass in clustered objects (galaxies). We use numerical simulations to follow the ﬂow of matter from low-density to high-density regions. In these simulations, we identify the current epoch by comparing the σ8 parameter of the spectrum with its observed value. Finally, in the third step we determine the power spectrum of matter in the linear regime and compare it with diﬀerent model predictions (Einasto et al. 1999b, Paper III). This approach is similar to Peacock & Dodds (1994) but, in addition, we also determine the primordial
arXiv:astro-ph/9812247v1 13 Dec 1998
ABSTRACT We calculate the mean power spectrum of all galaxies using published power spectra of galaxies and clusters of galaxies. On small scales we use the power spectrum derived from the 2-dimensional distribution of APM galaxies, since this sample is not inﬂuenced by redshift distortions and is the largest and deepest sample of galaxies available. On large scales we use power spectra derived from 3-dimensional data for various galaxy and cluster samples which are reduced to real space and in amplitude to the power spectrum of APM galaxies. We ﬁnd that available data indicate the presence of two diﬀerent populations in the nearby Universe. Clusters of galaxies sample a relatively large region in the Universe where rich, medium and poor superclusters are well represented. Their mean power spectrum has a spike at wavenumber k = 0.05 ± 0.01 h Mpc−1 , followed by an approximate power-law spectrum of index n ≈ −1.9 towards small scales. Some galaxy surveys (APM 3-D, IRAS QDOT, and SSRS+CfA2 130 Mpc) have similar spectra. The power spectrum found from LCRS and IRAS 1.2 Jy surveys is ﬂatter around the maximum, which may represent regions of the Universe with medium-rich and poor superclusters. Diﬀerences in power spectra for these populations may partly be due to the survey geometries of the datasets in question and/or to features of the original data analysis.