基于MSP430F149的频率计设计

设计了一种以超低功耗单片机MSP430F149为控制器,以高速的CPLD(复杂可编程逻辑器件)实现32位计数的频率计。在设计中应用单片机的数学运算和控制功能,实现了测量时间闸门的自动选择,频率和周期的统一处理。此外,利用MSP430F149内部的高速模拟比较器,实现了对正弦波小信号的预处理,使得该频率计能够在较宽的频率范围和幅度范围内进行测量。     

一种仿金刚石膜的研究

针对客户声称的表面覆金刚石膜（DF）的合成立方氧化锆进行常规宝石学检测,结果发现,样品为覆膜合成立方氧化锆,但样品表面的覆膜层硬度低、光滑平整,与多晶金刚石膜的粒状结构及单晶金月1石膜表面定向排列的突起等特征均不相同。为了确定表面覆膜层的成分,采用小角X射线衍射仪、X射线光电子能谱仪和红外光谱仪对样品表面的覆膜层进行了物相分析、化学成分分析及谱学测试。X射线衍射分析表明样品表面的覆膜层属于非晶物相;X射线光电子能谱分析表明样品的膜层主要化学成分为C,F。结合薄膜材料资料分析,初步确定其表面覆膜层可能属于非晶氟化碳（a—C：F）膜;红外光谱分析结果显示样品表面的膜层所导致的1068cm-1处的特征峰,进一步验证了X射线衍射分析结论。综合结果表明,该样品表面的覆膜层为非晶氟化碳（a—C：F）膜,是一种仿金刚石膜。     

大气重力波产生的大尺度赤道电离层扰动

本文研究了大气重力波产生的大尺度赤道电离层扰动的性质．当重力波的传播方向与磁场方向倾斜相交时,重力波在Ｆ区产生行进电离层扰动．当重力波垂直于磁场传播时,能触发等离子体Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性,形成大尺度赤道扩展Ｆ不均匀体．重力波引起的扩展Ｆ主要出现于晚上,行进电离层扰动则可能出现于任何时间．本文建立了行进电离层扰动和大尺度赤道扩展Ｆ的统一理论模型,深入全面地揭示了电离层扰动的性质．     

基于DSP的纳机电矢量水听器定向系统设计

利用单个矢量水听器实现水下声目标方位估计,较传统标量水听器估计方法简单且容易实现.纳机电矢量水听器具有灵敏度高、低频特性好、尺度小等优良特性.基于这种新型矢量水听器,采用DSPTMS320F2812处理器实现对水下声目标方位的实时估计和显示.给出了定向系统总体和各个模块设计原理,完成了相应的硬件电路与软件实现.试验结果表明:系统能稳定地对传感器的输出信号进行采集和角度计算,并能实时显示水下声目标的方位角度.角度误差小于2°.     

Transport and transformation of surface water masses across the Mascarene Plateau during the Northeast Monsoon season

The Mascarene Plateau lies in the south-west Indian Ocean between the islands of Mauritius and the Seychelles Bank, and is characterised by a series of shallow banks separated by deep (>1 000 m), narrow channels. The plateau acts as an obstruction to the general ocean circulation in this region, separating the westward-flowing South Equatorial Current (SEC) into two branches downstream of the plateau. In this article, we present the results of a survey conducted along the entire Mascarene Plateau during the Northeast Monsoon, in October–November 2008. In addition, data from Argo floats were used to determine the origin of water masses entering this region. The plateau contains three gaps through which branches of the SEC are channelled. The northern, central and southern gaps receive 14.93 Sv, 14.41 Sv and 6.19 Sv, respectively. Although there are differences in water-mass properties to the west and east of the Mascarene Plateau due to mixing, the SEC acts as a sharp boundary between water masses of southern and northern Indian Ocean origin. Mixing occurs in the central gap between intermediate water masses (Red Sea Water [RSW] and Antarctic Intermediate Water [AAIW]) as well as in the upper waters (Subtropical Surface Water [STSW] and Indonesian Throughflow Water [ITW]). Through the northern gap, mixing occurs between Arabian Sea High-Salinity Water (ASHSW), ITW and Tropical Surface Water (TSW), while through the southern gap, mixing occurs between STSW and ITW. North Indian Deep Water (NIDW) is present in the region but the plateau appears to have no effect on it.     

FY 2F卫星和毫米波云雷达云高观测的个例对比分析

风云二号静止卫星上装载有可见光、水汽、中长波红外等探测通道,其中红外通道资料可提供卫星云顶温度数据。基于FY-2F静止卫星云顶温度资料,结合局地实时探空数据对北京南郊和朝阳站点上空云层进行云高反演,并展开与地基毫米波云雷达探测云顶高关系的对比,分析3种不同云厚(薄云、适中、厚云)条件下的云高观测结果。研究结果表明,二者云顶高匹配度受几何云厚的影响,其吻合度呈现出厚云最佳,薄云最差的特征。     

Semi-analytical integration algorithms based on the use of several kinds of anomalies as temporal variable

One of the main problems in celestial mechanics is the management of long developments in Fourier or Poisson series used to describe the perturbed motion in the planetary system.In this work we shall develop a software package that is suitable for managing these objects. This package includes algorithms to obtain the inverse of the distance based on an iterative method, a set of integration algorithms according to several sets of temporal variables.This paper contains a comparative study on the use of the true, eccentric, and elliptic anomalies in semi-analytical methods on celestial mechanics.     

Application of lagged correlations between solar cycles and hydrosphere components towards sub-decadal forecasts of streamflows in the Western USA

Trade winds localized within the Western Equatorial Pacific express lagged and statistically significant correlations to sunspot numbers as well as to streamflow in rivers of the Southern Rocky Mountains. Both correlation sets were integrated in a linear regression analysis to produce relatively accurate sub-decadal streamflow forecasts for an annual and a 5-year average. In comparison to the autocorrelation technique, the prototyped method yielded the highest correlations, the highest goodness-of-fit scores, and the lowest root mean squared errors, for both the 5-year average and the annual average assignments. Of all of the cases examined, the highest Kolmogorov-Smirnov test scores between observation and prediction were found for the single solar-based forecast 5 years in advance for the 60-month average streamflow of the Animas River in New Mexico.     

An application of artificial intelligence for investigating the effect of COVID-19 lockdown on three-dimensional temperature variation in equatorial Africa

We present interesting application of artificial intelligence for investigating effect of the COVID-19 lockdown on 3-dimensional temperature variation across Nigeria (2°–15° E, 4°–14° N), in equatorial Africa. Artificial neural networks were trained to learn time-series temperature variation patterns using radio occultation measurements of atmospheric temperature from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). Data used for training, validation and testing of the neural networks covered period prior to the lockdown. There was also an investigation into the viability of solar activity indicator (represented by the sunspot number) as an input for the process. The results indicated that including the sunspot number as an input for the training did not improve the network prediction accuracy. The trained network was then used to predict values for the lockdown period. Since the network was trained using pre-lockdown dataset, predictions from the network are regarded as expected temperatures, should there have been no lockdown. By comparing with the actual COSMIC measurements during the lockdown period, effects of the lockdown on atmospheric temperatures were deduced. In overall, the mean altitudinal temperatures rose by about 1.1 °C above expected values during the lockdown. An altitudinal breakdown, at 1 km resolution, reveals that the values were typically below 0.5 °C at most of the altitudes, but exceeded 1 °C at 28 and 29 km altitudes. The temperatures were also observed to drop below expected values at altitudes of 0–2 km, and 17–20 km.     

2006年红花尔基樟子松林重大火灾发生的气象条件

利用极轨卫星遥感资料、气象资料,结合地理信息系统,对2006年5月16日红花尔基樟子松林区重大火灾发生、蔓延的气象条件进行了综合分析,结果表明：（1）高温少雨型严重干旱、大风是林火发生和蔓延的重要背景。（2）计算的森林可燃性的综合指标为395、423,表明应是雷击起火,与实际情况相符。（3）风力4级、气温5．9～6．5℃时,火场火势的蔓延速度为137．2hm2·h^-1;风力5级、气温7．6～8．4℃时,火场火势的蔓延速度为173．2hm^2·h^-1。（4）风力在4～5级之间变化、气温在5．9～8．4℃之间变化时,火场火势的蔓延速度一般为137～173hm2·h^1,可为以后的林火预报提供参考指标。