正确·流畅·美观——雷实教授点评参赛教师的书写展示

这15位选手的字写得都不错,比以往都有进步,这是我们大家努力的结果。我们是如何评价这些字的呢?首先是正确,不能写错别字。遗憾的是今天有选手太紧张了,写了错字。其次是要流畅。因为不够流畅,有的选手就没有在规定时间完成任务,稍微写快一点就好了。

High resolution GPR and its experimental study

We develop a high resolution ground penetrating radar system （LANRCS-GPR） based on the E5071B Vector Network Analyzer （VNA）. This system takes advantage of a wideband and adjustable frequency domain ground penetrating radar system and adds the characteristics of a network analyzer with ultra-wideband and high precision measurement. It adopts the LAN mode to concatenate system control that reduces construction cost and makes the system easy to expand. The high resolution ground penetrating radar system carries out real time imaging using F-K migration with high calculation efficiency. The experiment results of the system indicate that the LANRCS-GPR system provides high resolution and precision, high signal-to-noise ratio, and great dynamic range. Furthermore, the LANRCS-GPR system is flexible and reliable to operate with easy to expand system functions. The research and development of the LANRCS-GPR provide the theoretical and experimental foundation for future frequency domain ground penetrating radar production and also can serve as an experimental platform with high data gathering precision, enormous information capability, wide application, and convenient operation for electromagnetic wave research and electromagnetic exploration.

善用多边对话,促进个性化阅读

2011年版课标指出：＂阅读教学是学生、教师、教科书编者、文本之间对话的过程。＂可见这个＂对话＂,不仅是师生、生生之间,还是师、生与编者、与文本之间的多边对话。善用多边对话,可以让学生思维迸溅出火花、认识得以提升、情感得到融合、智慧得以生发,从而促进学生的个性化阅读。一、课前对话1.备课：教师与文本、编者的预先对话。华师大雷实教授说：＂语文教师在预先与文本对话（备课）时。

古诗词曾被请出民国教材

泰坦尼克号沉没是在1912年的4月,而这本教科书出版日期是1912年6月,泰坦尼克号沉没两个月后就进入教材。这说明一方面当时编写教材颇能与时俱进,紧跟重大时事新闻,另一方面编者对这一事件表现出的美德给予了肯定。

Experimental detection of bubble-wall interactions in a vertical gas–liquid flow

Bubble motions and bubble-wall interactions in stagnant liquid were experimentally investigated by high-speed CCD and PIV technique with the main feature parameters such as E?tv?s numbers Eo = 0.98–1.10, Morton number Mo = 3.21 × 10^(-9)and Reynolds numbers Re = 180 ~ 190. The effect of bubble injecting frequency and the distance S between the gas injection nozzle and the wall on the statistical trajectory of bubbles, average velocity distribution of flow field and Reynolds shear stress were studied in detail. It was shown that the combination of bubble injecting frequency and the distance S caused different bubble motion forms and hydrodynamic characteristics.When the normalized initial distance was very little, like S*≈ 1.2(here S*= 2S/d_e, and deis the bubble equivalent diameter), bubbles ascended in a zigzag trajectory with alternant structure of high and low speed flow field around the bubbles, and the distribution of positive and negative Reynolds shear stress looked like a blob. With the increase of distance S*, bubbles' trajectory would tend to be smooth and straight from the zigzag curve. Meanwhile, with the increase of bubble injecting frequency, the camber of bubble trajectory at 20<y<60 mm had a slight increase due to the inhibitory effect from the vertical wall. Under larger spacing, such as S*≈ 3.6, the low-frequency bubbles gradually moved away from the vertical plane wall in a straight trajectory and the high-frequency bubbles gradually moved close to the vertical wall in a similar straight trajectory after an unstable camber motion. Under the circumstances, high-speed fluid was mainly distributed in the region between the wall and the bubbles, while the relative large Reynolds shear stress mainly existed in the region far away from the wall.

Experimental study and numerical simulation of gas/particle flow in tunneling of mine

Respiration particles can be collected into a dust catcher by an inside inhalingand outside pressing particle collector. The work environment of the grab operator in tunneling mining was improved when a dust catcher is placed before the working face of thegrab operator. The particle movement was affected by the gas flow. The flow field insideand outside the dust collector was simulated. The effect of the operating parameter wasanalyzed. The numerical results show a good approach to predict the gas flow and particledistribution in the inside and outside of the particle collector.

FAST IMPLEMENTATION OF CONVOLUTION BACKPROJECTION ALGORITHM IN SPOTLIGHT SAR

A fast implementation of the convolution backprojection（CBP）algorithm in spotlight synthetic aperture radar（SAR）is presented based on the fast Fourier transform（FFT）.Traditionally,the computation of the ＇backprojection＇ process is expensive,since resampling in the process is implemented by using the interpolation operation.By analyzing the relative location relationship among different pixels,the algorithm realizes the ＇backprojection＇ using a series of FFTs instead of the interpolation operation.The point target simulation validates that the new algorithm accelerates the CBP algorithm,and the computational rate increases about 85%.

Effect of non-Gaussian properties of the sea surface on the low-incidence radar backscatter and its inversion in terms of wave spectra by an ocean wave spectrometer

The principle of ocean wave spectrometers was first presented several decades ago to detect the directional wave spectrum with real-aperture radar(Jackson,1981). To invert wave spectra using an ocean wave spectrometer,for simplicity,the hydrodynamic forcing and wave-wave interaction effect are neglected and a Gaussian slope probability density function(pdf) is used to calculate the normalized backscattering cross-section( σ 0) of the ocean surface. However,the real sea surface is non-Gaussian. It is not known whether the non-Gaussian property of the sea surface will affect the performance of the inversion of the wave spectrum if following existing inversion steps and methods. In this paper,the pdf of the sea surface slope is expressed as a Gram-Charlier fourth-order expansion,which is quasi-Gaussian. The modulation transfer function(MTF) is derived for a non-Gaussian slope pdf. The effects of non-Gaussian properties of the sea surface slope on the inversion process and result are then studied in a simulation of the SWIM(Surface Waves Investigation and Monitoring) instrument configuration to be used on the CFOSAT(China-France Oceanography Satellite) mission. The simulation results show that the mean trend of σ 0 depends on the sea slope pdf,and the peakedness and skewness coefficients of the slope pdf affect the shape of the mean trend of σ 0 versus incidence and azimuth; owing to high resolution of σ 0 in the range direction,MTF obtained using the mean trend of σ 0 is almost as accurate as that set in the direct simulation; in the inversion,if ignoring the non-Gaussian assumption,the inversion performances for the wave spectrum decrease,as seen for an increase in the energy error of the inverted wave slope spectrum. However,the peak wavelength and wave direction are the same for inversions that consider and ignore the non-Gaussian property.

RANS （Reynolds Averaged Navier-Stokes） and LES （Large Eddy Simulations） of the Air-Water TOPFLOW-PTS Experiment

The occurrence of a PTS （pressurized thermal shock） in a reactor vessel is an important phenomenon for assessing nuclear reactor safety. New experiment was conducted at HZDR （Helmholtz-Zentrum Dresden-Rossendorf）, focused on thermal mixing processes in the cold leg and the downcomer of two-phase PTS case. Present work reports CFD （computational fluid dynamics） ana｜ysis of steady-state air-water case. CFD analysis was conducted with two turbulence-modeling approaches, RANS （Reynolds Averaged Navier-stokes） and LES （large eddy simulations）. Multiphase situation was modeled with VOF （volume of fluid） approach. Simulations were performed using the FLUENT 12 package. Comparison of computed temperatures results and measurements along the thermo-couple lines revealed results depend on the turbulence model used.

难忘精彩

感受古都的独特韵味,享受语文的饕餮盛宴。在审计学院会场,有这样几个精彩的镜头最令人难忘——镜头一:大赛主持落落大方审计学院会场的主持人是南京市瑞金路小学的副校长倪鸣。她大方得体的主持风格为整场大赛增色不少。她的亲切、睿智的话语扫去选手很多的紧张。最令人印象深刻的是她的微笑。记得选手们进行知识素养答题时,她始终是面带微笑的,她这标志性的微笑,让比赛的氛围一下子没有了那种令人提心吊胆的紧张。

得失寸心知——精彩可以预约

(一)新课程实施以来,一个个新的语汇,俗称“新课程语汇”,频繁地出现在报刊杂志上。“预设”、“动态生成”、“未曾预约的精彩”等,相继进入我们的眼帘。尤其“未曾预约的精彩”,一下子变得时髦起来,成了许多老师的口头禅。我们常常看到这样的情景:一旦某一课上得好,便听到这个老师高兴地说:啊,未曾预约的精彩。前几天,我从一本杂志上看到一篇文章,一位青年老师在自己的教案不被学生接受的情况下,灵机一动,“甩掉教案、重新设计”,上出了精彩一课,他激动地高喊“

身残志坚的战士

湖北蒲圻市赵桥镇羊楼司村退伍军人、原民兵连长胡华伯,1975年,在一次民兵进行地雷实爆训练中,为保护战友的安全,他奋不顾身地排除哑爆,不幸引发了18颗连环雷,使其失去了双手和左腿。

大无畏的人——王杰

王杰,1942年出生在山东省金乡县华村(今金乡县王杰村),1961年8月应征参加中国人民解放军,次年2月加入中国共产主义青年团。入伍以后,王杰连续3年被评为'五好战士',两次荣立三等功,多次受奖,被评为模范团员。王杰曾在日记中写下'我们要一不怕苦,二不怕死,做一个大无畏的人。'并用自己的行动去实践,正所谓'哪里有困难,哪里最危险,哪里就有王杰。'1965年7月14日,王杰在进行民兵训练任务的最后一项训练——地雷实爆时。

Wind characteristics near the ground during typhoon Meari

Wind speed and direction data during typhoon Meari were obtained from eight anemometers installed at heights of 10, 20, 30, and 40 m on a 40-m tower built in the Pudong area of Shanghai. Wind-turbulence characteristics, including wind-speed profile, turbulence integral scale, power spectra, correlations, and coherences were analyzed. Wind-speed profiles varied with time during the passage of Meari. Measured wind-speed profiles could be expressed well by both a power law and a log law. Turbulence integral scales for u, v, and w components all increased with wind speed. The ratios of the turbulence scales among the turbulence components averaged for all 10-min data were 1：0.69：0.08 at 10 m, 1：0.61：0.09 at 20 m, and 1：0.65：0.13 at 40 m. The turbulence integral scales for the u and v components increased with average gust time, but the turbulence integral scale for the w component remained almost constant when the gust duration was greater than 10 min. The decay factor of the coherence function increased slightly with wind speed, with average values for longitudinal and lateral dimensions of 14.3 and 11.3, respectively. The slope rates of the turbulence spectra in the inertial range were less than -5/3 at first, but gradually satisfied the Kolmogorov 5/3 law. The longitudinal wind-power fluctuation spectrum roughly fitted the von Karman spectrum, but slight deviations occurred in the high-frequency band for lateral and vertical wind-power fluctuation spectra.

New numerical solution for self-acting gas journal bearings

Taking a small pressure change in the gas film of self-acting gas-lubricated journal bearings into account, the corresponding nonlinear Reynolds equation is linearized through appropriate approximation and a modified Reynolds equation is derived and solved by means of the finite difference method (FDM). The gas film pressure distribution of a self-acting gas-lubricated journal bearing is attained and the load capacity is calculated. The numerical solution has a better agreement with experimental data than a direct numerical solution for different values of the bearing number. It is of interest to note that the eccentricity ratio, at which the new numerical solution is in better agreement with experimental data, is different when the bearing number is changing. The new numerical solution is slightly larger when the eccentricity ratio is smaller, and becomes slightly smaller when the eccentricity ratio is larger.

Effects of Freestream Turbulence on Bypass Transition of Separated Boundary Layer on Low-Pressure Turbine Airfoils

This paper presents experimental studies on bypass transition of separated boundary layer on low-pressure turbine airfoils,focusing on the effects of freestream turbulence on the transition process.Hot-wire probe measurements are performed on the suction side of an airfoil in the low-pressure linear turbine cascade at several Reynolds number conditions.Freestream turbulence is enhanced by use of turbulence grid located upstream of the cascade.The results of this experimental study show that the location of boundary layer separation does not strongly de-pend on the freestream turbulence level.However,as the freestream turbulence level increases,the size of separa-tion bubble becomes small and the location of turbulent transition moves upstream.The size of separation bubble becomes small as the Reynolds number increases.At low freestream turbulence intensity,the velocity fluctuation due to Kelvin-Helmholtz instability is observed clearly in the shear layer of the separation bubble.At high frees-tream turbulence intensity,the streak structures appear upstream of the separation location,indicating bypass transition of attached boundary layer occurs at high Reynolds number.

A Study on High Subsonic Airfoil Flows in Relatively High Reynolds Number by Using OpenFOAM

In the present study,numerical calculations of the flow-field around the airfoil model are performed by using the OpenFOAM in high subsonic flows.The airfoil model is NACA 64A010.The maximum thickness is 10 % of the chord length.The SonicFOAM and the RhoCentralFOAM are selected as the solver in high subsonic flows.The grid point is 158,000 and the Mach numbers are 0.277 and 0.569 respectively.The CFD data are compared with the experimental data performed by the cryogenic wind tunnel in the past.The results are as follows.The numerical results of the pressure coefficient distribution on the model surface calculated by the SonicFOAM solver showed good agreement with the experimental data measured by the cryogenic wind tunnel.And the data calculated by the SonicFOAM have the capability for the quantitative comparison of the experimental data at low angle of attack.

Experimental investigation of Reynolds stress complex eddy viscosity model for coherent structure dynamics

Time sequence signals of streamwise and normal velocity components,as well as velocity strain rate,at different vertical locations in the turbulent boundary layer over a smooth flat plate in a wind tunnel have been finely examined by the use of double-sensor hot-wire anemometry.The local module maximum for wavelet coefficient of longitudinal velocity component,as a detecting index,is employed to educe the ejection and sweep process of the coherent structure burst in the turbulent boundary layer from the random fluctuating background.The coherent waveforms of Reynolds stress residual contribution term for random fluctuations to coherent structure,as well as the velocity strain rate of coherent structure,are extracted by the conditional phase average technique.Based on the theoretical analysis of eddy viscosity coefficient in complex eddy viscosity model for coherent structure,the macro-relaxation effect between Reynolds stress residual contribution term of random fluctuations to coherent structure and the velocity strain rate of coherent structure is studied and the variations of the phase difference between them across the turbulent boundary layer are investigated experimentally.The rationality of complex eddy viscosity model for coherent structure is confirmed through the investigation.