CO2滚动活塞膨胀机膨胀过程模拟计算

膨胀机工作过程模拟是以膨胀机实际工作过程为研究对象,综合各种因素,建立数学模型,利用计算机对模型进行数值求解,分析了膨胀机中工质的主要热力参数以及其能量、质量及功率等变化特性,计算了膨胀机输出功和效率等主要参数,通过分析,揭示了膨胀机的内部工作规律和改进膨胀机性能的途径.     

异向介质研究进展

介绍了异向介质的研究进展,其中包括基本理论的深化研究,介质新电磁特性的研究,一些新型结构的设计、仿真、实验、制作方法及其各自的优缺点,以及在波导、天线、微波器件等各个领域的应用.     

Saturation of Photoassociation in Cs Magneto-optical Trap

An ultrahigh resolution photoassociation spectrum of caesium atoms in a magneto-optical trap is presented. Hyperfine structure of the excited state molecule is obtained by using the lock-in method based on modulated cold atoms in this spectrum. Amplitude of resonant lines related to the rotational levels increases with photoassociation laser intensity, and saturation effect of photoassociation of cold atoms is observed in our experiment. The saturation intensity of photoassociation is deduced by fitting the experimental data to asaturation model based on scattering theory. Differences among saturation intensities of different rotational progressions in the υ=55 vibrational state of the caesium molecular long-range 0_g^- state have been found.     

B位Co掺杂对Sr14C24O41的结构和电输运的影响

采用固相反应法制备了系列Sr14（Cu1-xCox）24O41（x=0,0.02,0.06,0.1,0.14,0.18）的样品,X-射线衍射结果显示所有样品均为单相,且Co的掺杂几乎不改变样品的晶格常数,电子衍射和X-射线光电子能谱的测量结果证实Co替代的是链上的Cu原子;电输运的测量显示,Co掺杂样品表现为半导体行为,且渡越温度T随掺杂量的增加逐渐减小.     

电沉积二氧化钛功能薄膜的制备与组织转变研究

采用直流电沉积方法,在石墨板上成功制备了半导体二氧化钛功能薄膜前驱体,分析讨论了电沉积过程中实验参数对TiO2前驱体成膜的影响,获得了制备二氧化钛膜最佳工艺参数.TiO2前驱体沉积速率随着电流密度的增大而增加,为了保证薄膜质量,将电流密度控制在5～45mA/cm2之间;溶液浓度对沉积速率也有影响,当溶液中TiCl4:H2O2=1:2时沉积速率最大;最佳沉积温度为5-10℃.运用差热分析、XRD相结构分析和SEM等手段,研究了该前驱体到锐钛矿相(anatase)和金红石相(rutile)二氧化钛的组织相转变过程,300℃热处理得到锐钛矿相的二氧化钛,650℃热处理后出现金红石相.     

基于MATLAB的二元线性回归在小孔流速实验中的应用

利用MATLAB软件对相关物理量进行二元线性回归拟合,求出了拟合曲线的待定参数和置信区间,拟合曲线与实验测试数据点符合较好。总结出小孔流速的经验公式,并对减少实验误差的途径进行了讨论。     

A NUMERICAL AND ANALYTICAL STUDY ON A TAIL-FLAPPING MODEL FOR FISH FAST C-START＊

The force production physics and the flow control mechanism of fish fast C-start are studied numerically and theoretically by using a tail-flapping model. The problem is simplified to a 2-D foil that rotates rapidly to and fro on one side about its fixed leading edge in water medium. The study involves the simulation of the flow by solving the two-dimensional unsteady incompressible Navier-Stokes equations and employing a theoretical analytic modeling approach. Firstly, reasonable thrust magnitude and its time history are obtained and checked by fitting predicted results coming from these two approaches. Next, the flow fields and vortex structures are given, and the propulsive mechanism is interpreted. The results show that the induction of vortex distributions near the trailing edge of the tail are important in the time-averaged thrust generation, though the added inertial effect plays an important role in producing an instant large thrust especially in the first stage. Furthermore, dynamic and energetic effects of some kinematic controlling factors are discussed. For enhancing the time-averaged thrust but keeping a favorable ratio of it to time-averaged input power within the limitations of muscle ability, it is recommended to have a larger deflection amplitude in a limited time interval and with no time delay between the to-and-fro strokes. The project supported by the CAS (KJCX-SW-L04)     

Cold cesium molecules produced directly in a magneto-optical trap

We report on the observation of ultracold ground electric-state cesium molecules produced directly in a magneto- optical trap with a good signal-to-noise ratio. These molecules arise from the photoassociation of magneto-optical trap lasers and they are detected by resonantly enhanced multiphoton ionization technology. The production rate of ultracold cesium molecules is up to 4×10⁴ s^-1. We measure the characteristic time of the ground electric-state cesium molecules generated in the experiment and investigate the Cs₂⁺ molecular ion intensity as a function of the trapping laser intensity and the ionization pulse laser energy. We conclude that the production of cold cesium molecules may be enhanced by using appropriate experimental parameters, which is useful for future experiments involving the production and trapping of ultracold ground electric-state molecules.     

Preliminary research on the relationship between long-range correlations and predictability

By establishing the Markov model for a long-range correlated time series (LRCS) and analysing its evolutionary characteristics, this paper defines a physical effective correlation length (ECL) τ, which reflects the predictability of the LRCS. It also finds that the ECL has a better power law relation with the long-range correlated exponent γ of the LRCS: τ= Kexp (-γ/0.3)+Y, (0 < γ < 1) -- the predictability of the LRCS decays exponentially with the increase of γ. It is then applied to a daily maximum temperature series (DMTS) recorded at 740 stations in China between the years 1960--2005 and calculates the ECL of the DMTS. The results show the remarkable regional distributive feature that the ECL is about 10--14 days in west, northwest and northern China, and about 5--10 days in east, southeast and southern China. Namely, the predictability of the DMTS is higher in central-west China than in east and southeast China. In addition, the ECL is reduced by 1--8 days in most areas of China after subtracting the seasonal oscillation signal of the DMTS from its original DMTS; however, it is only slightly altered when the decadal linear trend is removed from the original DMTS. Therefore, it is shown that seasonal oscillation is a significant component of daily maximum temperature evolution and may provide a basis for predicting daily maximum temperatures. Seasonal oscillation is also significant for guiding general weather predictions, as well as seasonal weather predictions.