面对“真相衰退”,我们如何应对?

互联网和社交媒体的兴起改变了传媒生态环境,意见和个人经验逐渐成为了“压倒性事实”,公众对权威事实信源的信任也逐步下降。基于此,本文梳理了“真相衰退”呈现的四大趋势,从认知的偏见、信息系统的变化以及数字媒介素养教育的滞后三个维度,分析了“真相衰退”产生的缘由,并结合我国实际情况提出了应对策略。

“真相坍塌”时代传播学教师的使命研究

本文引进了国外学者提出的"真相坍塌"(truth decay)概念,阐述了"真相坍塌"时代传播学教师所应肩负的多重使命和践行使命的路径。指出传播学教师应以教书育人、著书立说和躬身实践之混合方式,服务国家发展和人类文明进步。

Imaging simulation and analysis of attitude jitter effect on topographic mapping for lunar orbiter stereo optical cameras

The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching.In this work,an imaging simulation method consid-ering the attitude jitter is presented.The impact analysis of different attitude jitter on terrain undulation is conduct-ed by simulating jitter at three attitude angles,respectively.The proposed simulation method is based on the rigor-ous sensor model,using the lunar digital elevation model(DEM)and orthoimage as reference data.The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter.Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit.Experi-mental analyses were conducted by the DEM with the simulated stereo image.The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping.The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison.

从多元文化话语符号象征视角筑牢外语学习的思政防线

外语学习是当今世界交流与合作的一种需求。置身于多元文化的信息时代,良莠不齐的知识充斥其间,如何正确育人使之成为社会主义接班人?文章提出在语言学习中要会识别语言符号背后象征意义的“陷阱”,了解话语“真相”的指向性、警惕意识形态颠覆,将家庭教育、学校教育和社会教育形成一个系统育人工程,坚持正确的价值观,将育人视为终身目的贯彻其中,筑牢高校思政防线。

Magnesium vapor nucleation in phase transitions and condensation under vacuum conditions

Recent findings related to coagulable magnesium vapor nucleation and growth in vacuum were assessed critically, with emphasis on understanding these processes at a fundamental molecular level. The effects of magnesium vapor pressure, condensation temperature, and condensation zone temperature gradient on magnesium vapor nucleation in phase transitions and condensation from atomic collision and coacervation with collision under vacuum conditions were discussed. Magnesium powder and magnesium lump condensates were produced under different conditions and characterized by scanning electron microscopy （SEM） and energy-dispersive X-ray spectroscopy （EDS）. The right condensation zone temperature approach to the liquid transition primarily improved the magnesium vapor concentration rate. The gas-solid phase transition was primarily inhibited by setting a small condenser temperature gradient. Under the right condensation temperature and temperature gradients, increasing magnesium vapor partial pressure improved crystallization and reduced the oxidation rate.

Recycling of metals from waste Sn-based alloys by vacuum separation

In order to recycle waste Sn-based alloys, the vapor-liquid phase equilibrium composition diagrams of Sn-Pb, Sn-Sb and Sn-Zn binary systems were calculated. The calculated results indicate that Pb, Sb and Zn can be separated from Sn effectively. Based on the above calculation, the industrial experiments of vacuum distillation of Sn-Pb alloy, Sn-Pb-Sb alloy, Sn-Pb-Sb-As alloy, crude Sn and Sn-Zn alloy with different contents were carried out. The experimental results show that Pb(>99% Pb) and Sn(≤0.003% Pb) were obtained simultaneously while Sn-Pb alloy was subjected to vacuum distillation; the crude Sn(>90% Sn, ≤ 2% Pb, ≤6% Sb) and crude Pb(≤2% Sn) were obtained simultaneously while a single vacuum distillation was carried out for Sn-Pb-Sb alloy; the Pb and Bi contents in the Sn ingot(99.99% Sn) achieve the grade A of GB/T 728—2010 standard, more than 50% of As and Sb was removed after vacuum distillation of crude Sn; Zn(<0.002% Sn) and Sn(about 3% Zn) were obtained while vacuum distillation of Sn-Zn alloy was conducted at 1173 K, 20-30 Pa for 8-10 h.

Application of molecular interaction volume model in separation of Pb-Sn-Sb ternary alloy by vacuum distillation

Based on the molecular interaction volume model （MIVM）, the activities of components of Pb Sn Sb ternary alloy were predicted. The vapo^liquid phase equilibrium of Pb-Sn-Sb alloy system was calculated using the activity coefficients of Pb Sn-Sb alloy system in the process of vacuum distillation. The calculated results show that the content of Sn in vapor phase increases with the increasing distillation temperature and content of Sn in liquid phase. However, the content of Sn in vapor phase is only 0.45% （mass fraction） while 97% in liquid phase at 1100 ℃, which shows that the separating effect is very well. Experimental investigations on the separation of Pb-Sn-Sb ternary alloy were carried out in the distillation temperature range of 1100-1300 ℃ under vacuum condition. It is found that the Sn content in vapor phase is 0.54% while 97% in liquid phase at 1100 ℃. Finally, the predicted data were compared with the experimental results showing good agreement with each other.

浅析国家艺术基金项目——独幕剧《菩提青蛇》人物视角观及选择观

独幕剧《菩提青蛇》是2015年度国家艺术基金项目(项目编号:20152002)。作为北京联合大学首个国家艺术基金项目,得到了学校、学院的高度重视。作为《菩提青蛇》的编剧、导演,笔者从一度创作的源头出发,梳理人物视角,阐述不同人物眼中的"真相",并理性分析人物为其行动所做的选择。

Growth of Strained Si_(1-x)Ge_x Layer by UV/UHV/CVD

Strained Si_ 1-xGe_x and Si materials are successfully grown on Si substrate by ultraviolet light chemical vapor deposition under ultrahigh vacuum at a low substrate temperature of 450℃ and 480℃,respectively.At such low temperature,autodoping effects from the substrate and interdiffusion effects at each interface could be suppressed efficiently.The strained Si_ 1-xGe_x and multilayer Si_ 1-xGe_x/Si structures are examined by X-ray diffraction,SMIS,etc.,and it is found that the materials have good crystallinity and the rising and falling edges are steep.The technique has a capability of growing high-quality Si_ 1-xGe_x/Si strained layers.

The anti-correlation method for removing harmonic distortion in vibroseis slip-sweep data

The slip-sweep technique is one of the high-efficiency, high-fidelity, and environmental vibroseis seismic prospecting techniques which consists of a vibrator group sweeping without waiting for the previous group＇s sweep to terminate. The cycle time can be reduced drastically and hence the production efficiency can be increased significantly but harmonic distortion of one sweep will leak into the record of the other sweep. In this paper, we propose an anti-correlation method for removing harmonic distortion in vibroseis data. This method is based on decomposition of the ground force signal into fundamental and harmonic components. Then the corresponding anti-correlation operator can be computed to estimate the energy of each harmonic after correlating the vibroseis data with the corresponding harmonic component. Finally, the vibroseis harmonic noise to be removed can be obtained by subtracting the extracted harmonic noise from the traces of the previous group＇s sweep. The advantage of the proposed method is that it can process both uncorrelated and correlated vibroseis seismic data. Moreover, the algorithm is simple, stable, and computationally fast. Especially, the significant contribution of this method is a considerable reduction in the harmonic without any alteration of the desired signals. The method was tested on both synthetic and field data sets to validate the good harmonic noise suppression results.

Epitaxy of SiGe HBT Structure by High Vacuum/Rapid Thermal Processing/Chemical Vapor Deposition

The strained SiGe material has been grown by using the newly developed High Vacuum/Rapid Thermal Processing/Chemical Vapor Deposition (HV/RTP/CVD) system.Device quality material is grown by handling process after careful design. The Ge fraction varies up to 0 25, and the n and p type doping is well controlled,which are both adapted to the fabrication of Heterojunction Bipolar Transistors (HBT). The SiGe HBT structure, namely n Si/i p + i SiGe/n Si structure, has been investigated, with which, the HBTs are fabricated and show good performance. The new system has been proved potential and practicable.

Nanoindentation tests on single crystal copper thin film with an AFM

Nanoindentation tests performed in a commercial atomic force microscope have been utilized to directly measure the elastic modulus and the hardness of single crystal copper thin films fabricated by the vacuum vapor deposition technique. Nanoindentation tests were conducted at various indentation depths to study the effect of indentation depths on the mechanical properties of thin films. The results were interpreted by using the Oliver-Pharr method with which direct observation and measurement of the contact area are not required. The elastic modulus of the single crystal copper film at various indentation depths was determined as (67.0±(6.9) GPa) on average which is in reasonable agreement with the results reported in literature. The indentation hardness constantly increases with decreasing indentation depth, indicating a strong size effect.

Study on Grain Refining and Metamorphism of ZL111 Aluminium Alloys

Vacuum sintering and ball milling methods were employed in the preparation process of Ti-C grain refine- ment and the ability of refiners with varying ratios of Ti and C to refine ZL111 crystal grains was tested. The refinement effect of the Ti-C ratios on tensile strength, elongation percentage, Brinell hardness, pro-eutectoid αAl and the size of the Si phase of ZL111, after modification by rare-earth and strontium nitrate, were studied by means of metallographic examination, SEM and mechanical property tests. The results show that there is an obvious increase in the tensile strength and elongation percentage of refined ZL111 with these new Ti and C refiner compounding powders, while Brinell hardness remained more or less constant. The pro-eutectoid αAl is considerably reduced in size and the Si phase shows a finer and rounder structure. The refiner exhibits a good grain refining performance when the Ti-C ratio is 25:1, for Al crystals can favorably easily form nuclei and grow up along the TiC surface thanks to the TiAl3 generated by sur- plus Ti and Al. The mechanical properties have clearly been improved by the addition of strontium nitrate to ZL111. The effective factors in the modification of mechanical properties of ZL111 are in order of importance: strontium nitrate, Ti-C ratio and rare earth.

Interval Sampling Method for Steady-State Simulation Output Analysis

A new algorithm namely the interval sampling method, applicable to the analysisof steady-state simulation output is proposed. This algorithm uses the time series analysisto carry out conrrelation analysis of the steady-state simulation output so as to obtain theobservation data which are actually uncorrelated in nature. On the basis of theseuncorrelated data gathered, some satisfactory deductions cam be made on the data under re search. A comparison between batch means method and the interval sampling method hasbeen performed by taking the M/M/l queuing system as an example. The results attestedthat the interval sampling method is mere accurate than the batch means method.

Physical simulation of rock burst induced by stress waves

The behavior of stress wave propagation in rock walls and the process of rock bursts were simulated by application tests of material similar to rock. Results show that 1) the attenuation characteristics of stress waves were related to the material proper-ties, stress waves attenuate more quickly in soft material and 2) when the explosion load was applied at the top of the roadway, the number and the length of the cracks increased with a decrease in the distance between the explosive point and roof of the roadway. When the distance was 280 mm, only some chips appeared near the source, when the distance was 210 mm, some small cracks started to appear near the road-rib and when the distance was reduced to 140 mm, larger cracks appeared at the road-rib. It can be concluded that, under a given stress the number of cracks is closely related to the intensity of stress waves. The cracks in the sur-rounding rock can be reduced by controlling the intensity of the stress waves and rock bursts can be avoided to some extent by pre-venting the formation of layered crack structures. A new experimental approach has been provided for studying rock bursts by using physical simulation.

Image Distortion of Optical Coherence Tomography

A kind of image distortion in Optical Coherence Tomography (OCT) resulted from average refractive index changes between structures of bio tissue is discussed for the first time.Analysis is given on following situations:1) Exact refraction index changes between microstructures;2)The gradient of average refractive index change between different tissue layers is parallel to the probe beam;3) The gradient of average refractive index change is vertical to the probe beam.The results show that the image distortion of situation 1) is usually negligible;in situation 2) there is a spread or shrink effect without relative location error; however,in situation 3) there is a significant image error inducing relative location displacement between different structures.Preliminary design to eliminate the distortion is presented,the method of which mainly based on the image classification and pixel array re arrangement.

Casimir Force at a Finite Cut-Off

We calculate the Casimir force at a finite cut-off A by summing the forces induced by the all fluctuation modes. We show that the Casimir force is independent of the cut-off function in the limit L∧ → ∞. There is a correction in the order of （L∧）^-2, when L∧ is finite and large. This correction becomes remarkable when L is comparable with the microscopic length scale ∧^-1. It has been demonstrated that the Casimir force at a finite cut-off should be defined by summing forces of all fluctuation modes, instead of the derivative of Casimir energy with respect to L where an additional derivative of the cut-off function has been introduced.

Quantum Entanglement Dynamics of Two Atoms in Quantum Light Sources

Quantum entanglement dynamics of two Tavis-Cummings atoms interacting with the quantum light sourcesin a cavity is investigated.The results show the phenomenon that the concurrence disappears abruptly in a finite time,which depends on the initial atomic states and the properties of squeezed states.We find that there are two decoherencefreestates in squeezed vacuum fields:one is the singlet state,and the other entangled state is the state that combinesboth excited states and ground states with a relative phase being equal to the phase of the squeezed state.

Effects of Vacuum-Induced Coherence on One- and Two-Photon Absorption Spectra of Transient Process in a Y-Type System

We investigate the influence of the vacuum-induced coherence on one- and two-photon absorption of the transient process in a four-level Y-type atomic system. We find that the one- and two-photon t, ransient absorption and amplification properties are quite sensitive to the vacuum-induced coherence. It is also shown that the one- and two-photon absorption spectra of the transient process can be dramatically affected by modulating the relative phase of the applied fields. By apprdpriately choosing the relative phase, the amplification of the probe field can be achieved.

Theoretical research on vacuum separation of Au-Ag alloy

To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.