Ionospheric variability at taiwan low latitude station: Comparison between observations and IRI-2001 model

This paper presents the observed ionospheric F-region critical frequency, foF2, and peak height, hmF2, at northern crest of equatorial ionization anomaly (EIA) area station, namely Chung-Li (24.9°N, 121.1°E, dip 35°), and to be compared with International Reference Ionosphere model (IRI-2001) predictions for the period from 1994 to 1999, corresponding to half of the 23rd solar cycle. The diurnal and seasonal variation of foF2 and hmF2 are analyzed for different solar phases, respectively. The result shows the largest discrepancies were observed during nighttime for foF2 and hmF2, respectively. The value of foF2 both CCIR and URSI selected in the IRI model produced a good agreement during the daytime and underestimated during the noon time for high solar activities. The underestimation at noon time is mainly caused by the fountain effect from equator. Further, the peak height hmF2 shows a larger variability around the midnight than daytime in the equinox and winter seasons and reserved in summer, respectively. The study shows that the monthly median values of observed hmF2 is somewhat lower than those predicated by the IRI model, at night time in all the seasons except the period of 04:00–06:00 LT and reverse at daytime in summer. In general the IRI model predictions with respect to the observed in hmF2 is much better than foF2. The percentage deviation of the observed foF2 (hmF2) values with respect to the IRI model varies from 5% to 80% (0–25%) during nighttime and 2–17% (0–20%) at daytime, respectively. In general, the model generates good results, although some improvements are still necessary to implement in order to obtain better simulations for ionospheric low-latitudes region.     

Gas exchange rates of potato stands for bioregenerative life support

Plants can provide a means for removing carbon dioxide (CO₂) while generating oxygen (O₂) and clean water for life support systems in space. To study this, 20 m² stands of potato (Solanum tuberosum L.) plants were grown in a large (113 m³ vol.), atmospherically closed chamber. Photosynthetic uptake of CO₂ by the stands was detected about 10 DAP (days after planting), after which photosynthetic rates rose rapidly as stand ground cover and total light interception increased. Photosynthetic rates peaked ca. 50 DAP near 45 μmol CO₂ m⁻² s⁻¹ under 865 μmol m⁻² s⁻¹ PPF (average photosynthetic photon flux), and near 35 μmol CO₂ m⁻² s⁻¹ under 655 μmol m⁻² s⁻¹ PPF. Short term changes in PPF caused a linear response in stand photosynthetic rates up to 1100 μmol m⁻² s⁻¹ PPF, with a light compensation point of 185 μmol m⁻² s⁻¹ PPF. Comparisons of stand photosynthetic rates at different CO₂ concentrations showed a classic C₃ response, with saturation occurring near 1200 μmol mol⁻¹ CO₂ and compensation near 100 μmol mol⁻¹ CO₂. In one study, the photoperiod was changed from 12 h light/12 h dark to continuous light at 58 DAP. This caused a decrease in net photosynthetic rates within 48 h and eventual damage (scorching) of upper canopy leaves, suggesting the abrupt change stressed the plants and/or caused feedback effects on photosynthesis. Dark period (night) respiration rates increased during early growth as standing biomass increased and peaked near 9 μmol CO₂ m⁻² s⁻¹ ca. 50 DAP, after which rates declined gradually with age. Stand transpiration showed a rapid rise with canopy ground cover and peaked ca. 50 DAP near 8.9 L m⁻² d⁻¹ under 860 μmol m⁻² s⁻¹ PPF and near 6.3 L m⁻² d⁻¹ under 650 μmol m⁻² s⁻¹ PPF. Based on the best photosynthetic rates from these studies, approximately 25 m² of potato plants under continuous cultivation would be required to support the CO₂ removal and O₂ requirements for one person.     

An evaluation of the IRI-2007 storm time model at low latitude stations

This paper discusses the ability of the International Reference Ionosphere IRI-2007 storm time model to predict foF2 ionospheric parameter during geomagnetic storm periods. Experimental data (based on availability) from two low latitude stations: Vanimo (geographic coordinates, 2.7 °S, 141.3 °E, magnetic coordinates, 12.3 °S, 212.50 °E) and Darwin (geographic coordinates, 12.45 °S, 130.95 °E, magnetic coordinates, 22.9 °S, 202.7 °E) during nine storms that occurred in 2000 (Rz₁₂ = 119), 2001(Rz₁₂ = 111) and 2003 (Rz₁₂ = 64) are compared with those obtained by the IRI-2007 storm model. The results obtained show that the percentage deviation between the experimental and IRI predicted foF2 values during these storm periods is as high as 100% during the main and recovery phases. Based on the values of “relative deviation module mean” (RDMM) obtained (i.e. between 0.08 and 0.60), it is observed that there is a reasonable to poor agreement between measured foF2 values and the IRI-storm model prediction values during main and recovery phases of the storms under investigation. As a result, in addition to other studies that have been carried out from different sectors, more studies are required to be carried out. This will enable IRI community to improve on the present performance of the model. In general the IRI-storm model predictions follow normal trend of the foF2 measured values but does not reproduce well the measured values.     

二维射流的稳定性分析与流动控制

本文在绝对／对流不稳定性的理论框架下，对二维射流的稳定性进行了数值分析。研究表明射流流场各局部剖面是对流不稳定的，不会产生整体失稳，射流频率由流场中最大增长的不稳定频率确定。将一ＮＡＣＡ０１２翼型放置于射流势流核心区中，改变翼型的偏转角度θ，可使射流剪切层频率与翼型尾流频率发生共振，整个流场产生自激振荡，加强了射流与外界流场和混合，并使射流发生矢量偏转。     

SnO2薄膜在可见光区的气敏透光研究

研制以ＳｎＯ２江膜作敏感材料的气敏比色皿，发现在可见光区透射率随被测气体浓度伯增大而增大，并解释敏感机理。     

基于VHDL的I^2C总线IP核的设计

简述了I~2C总线的特点；并详细描述了一种在FPGA中实现I~2C总线IP核的设计方法；最后给出I~2C总线IP核在主模式下的收发数据仿真时序图以及实现结果。     

Aerodynamic optimization and mechanism design of flexible variable camber trailing-edge flap

Trailing-edge flap is traditionally used to improve the takeoff and landing aerodynamic performance of aircraft.In order to improve flight efficiency during takeoff,cruise and landing states,the flexible variable camber trailing-edge flap is introduced,capable of changing its shape smoothly from 50% flap chord to the rear of the flap.Using a numerical simulation method for the case of the GA(W)-2 airfoil,the multi-objective optimization of the overlap,gap,deflection angle,and bending angle of the flap under takeoff and landing configurations is studied.The optimization results show that under takeoff configuration,the variable camber trailing-edge flap can increase lift coefficient by about 8% and lift-to-drag ratio by about 7% compared with the traditional flap at a takeoff angle of 8°.Under landing configuration,the flap can improve the lift coefficient at a stall angle of attack about 1.3%.Under cruise state,the flap helps to improve the lift-todrag ratio over a wide range of lift coefficients,and the maximum increment is about 30%.Finally,a corrugated structure–eccentric beam combination bending mechanism is introduced in this paper to bend the flap by rotating the eccentric beam.     

万能工具显微镜智能化改造

以国产新添数显万能工具显微镜为例，介绍了万能工具显微镜智能化改造的基本原理，两维测量软件的主要功能以及通用几何元素及其形位误差的数学算法，探讨了保证检测揩度的若干措施，并给出了U1、U2校准比对结果。     

B2-RuAl金属间化合物国内外研究进展

通过整理国内外有关B2-RuAl合金研究的资料,系统介绍B2-RuAl合金的基本物性、合金化效应和制备方法的研究现状,指出B2-RuAl合金作为金属间化合物又将是材料研究的新热点,它的应用将对促进新一代元器件的出现发挥重要的作用,同时对其优异室温塑性原因的研究将有利于找到提高其他金属间化合物室温塑性行之有效的解决措施。     

ZrB2-SiC复合陶瓷双尺度热应力分析

基于双尺度渐近分析方法,对ZrB2-SiC陶瓷的细观热应力场进行数值模拟,研究了SiC夹杂的含量、颗粒尺寸和中心距对细观ZrB2-SiC陶瓷单胞热应力场分布的影响。结果发现：在ZrB2-SiC陶瓷材料制备冷却过程中,SiC含量越高,材料越易产生微裂纹;当夹杂含量一定时,SiC夹杂颗粒的尺寸越大或夹杂颗粒间的中心距越小,材料越易产生微裂纹。数值计算结果与扫描电镜（SEM）照片吻合。