Shuttle-Mir's lessons for the International Space Station

NASA's groundbreaking and controversial partnership in the Mir program is winding down. For more than two years, a stream of US astronauts has been sent aloft, one after the other, to join the crew aboard the Russian space station. Now the space partners and a dozen associated nations are collaborating on a yet more ambitious joint space project, the International Space Station (ISS), due later this year for the launch of its first element, a Russian-built cargo block. This paper explores just what the Shuttle-Mir union has taught participants in the ISS project about lengthy space operations, and at what cost     

Saving Mir with a rope trick

Using a fabled “skyhook” of engineering folklore (known as firefly), Russia's ailing Mir space station may soon lift itself by its own bootstraps into a higher, more stable orbit. That feat, though, is raising fears at NASA that the development of its supposed replacement, the International Space Station (ISS) will be upset. At present, Mir is orbiting without a crew. The last two cosmonauts to visit the station returned to Earth in June 2000. The next crew is set to go up in November 2000, according to MirCorp, the private consortium that agreed to lease the station for commercial purposes. What's more, in an effort to add years to the station's lifespan, cosmonauts will begin testing a new propulsion technology some time later this year or next. The heart of the new technology is an electrodynamic tether, a long thin wire that will attach to Mir and draw electrons from Earth's ionosphere. As with an electric motor, this current-carrying wire will experience a force as it passes through Earth's magnetic field, a force that will, it is hoped, stabilize Mir's altitude     

信息化条件下船员心肺复苏三段式培训模式的研究

信息化条件下船员CPR三段式培训模式是南通航运职业技术学院航海急救培训团队借鉴国内外权威机构CPR培训的做法, 在长期教学实践中逐渐形成的一套较为成熟的培训方案。该培训模式针对以往教学中普遍存在的理论和技能丢失的问题, 通过优化教学流程, 采用线上教学和线下教学交替进行的方式, 实现了师生线上线下的良性互动。同时, 将信息化教学手段引入船员CPR培训, 打破了时间和空间的局限, 为CPR培训的有效性提供了保证, 为探索建立规范、高效和易于实施的船员CPR培训模式提供了参考。     

Estimating aircraft SAR response characteristics and ocean wavespectra in the Labrador Sea Extreme waves Experiment

The Labrador Extreme Waves Experiment (LEWEX) was an international effort to assess methods of measuring and modeling the directional aspects of wind-generated ocean waves, especially their evolution in the presence of rapidly turning winds. The author describes data-processing methods that have been developed to derive estimates of two-dimensional wave height-variance spectra from the ocean imagery obtained in LEWEX by a C-band synthetic aperture radar (SAR) system aboard a Canadian CV-580 aircraft. SAR spectra at altitudes of 20000 and 12000 ft are compared for both large (~50°) and small (~25°) radar look angles. Independence spectral estimates from both a surface contour radar and a radar ocean wave spectrometer aboard a NASA aircraft are used to verify the surface wave spectrum     

1342nm激光通过周期极化钽酸锂产生红光和蓝光的研究

激光二极管(LD)抽运Nd：YVO4激光器通过周期极化的钽酸锂(PPLT)，利用非线性光学中倍频与和频的原理。为了实现准相位匹配调控周期极化钽酸锂的温度，当基频光与倍频光满足准相位匹配时，产生671nm的红光和447nm的蓝光。当1342nm基波的平均功率为1．58W时，输出671nm红光的最大平均功率为750mW，对应的匹配温度为92．3℃。半峰全宽温度值为3．2℃，输出447nm蓝光的最大平均功率为128mW。对应的匹配温度为83．2℃。半峰全宽温度值为4．5℃，其红光的光-光转换效率为47．4％，蓝光转换效率为8．1％。经过一段时间观察，由周期极化的钽酸锂倍频与和频得到的红光和蓝光输出稳定，结果显示周期极化的钽酸锂可以构造全固态红光和蓝光双波长激光器。     

India's new government pledges to continue economic reforms - but investors worry a fractious coalition will be bad for business

Will India's economic and high-tech boom continue? The country's GNP grew nearly 8 percent last year, and India seemed set to boast a trillion-dollar economy by 2010. But worries about its future set in virtually the moment election results were declared. This is because investors worry a fractious coalition will be bad for business.     

Comparison of measured and predicted field strengths of medium frequency sky waves over short distances in Japan

Nighttime sky waves of four medium frequencies were observed at distances of not larger than about 300 km in Japan for one to two years of high and low solar activities. The sporadic E (Es) layer always appeared with high probability. Analyzing these data, the following results were obtained: 1) the measured median field strengths are different by at least more than 7 dB from full wave predicted values for the international reference ionosphere (IRI) without the Es-layer. But these agree fairly well with the full wave calculation for IRI with the Es-layer, 2) the field strength approximates the Rayleigh distribution, 3) according to the data for high solar activity, the sky wave appears rapidly after sunset, and during the two to six hours after sunset all median field strengths are about constant.     

Modulations of laser signals by water waves observed by a boxcarintegrator

This paper describes a new measurement technique for active remote sensing of water waves using a lidar. To demonstrate this technique, a series of experiments studying interactions of laser pulses with water waves was performed in an NRL wave tank. This technique used a commercially available boxcar integrator to sample IR laser pulses reflected from water waves. These water waves were generated either by artificial winds or a mechanical paddle in the wave tank. The boxcar integrator samples these laser waveforms as a function of windspeeds and paddle frequencies. This paper describes the experimental technique, the measurements, and the data analyses. For wind-generated water waves, results of the data analyses show that lidar-detected laser energies and the lidar-detected water-wave frequencies are functions of windspeeds. For paddle waves, the measurement data show that the laser backscattering cross-section from a water wave is a function of height positions within the water wave. The measurement data successfully demonstrate a boxcar-integrator waveform-sampling technique as an alternative technique to, and possible improvement over, a conventional waveform digitizer. The potential application of this technique in active remote sensing is discussed     

压电基片上集成微通道数字微流体微混合器研究

微流体在压电基片上输运往往偏离声表面波传播方向,尤其是当压电基片表面疏水层不很均匀时,给微流体诸如混合等操作带来不便。在1280旋转Y切割X传播方向的LiNbO3基片上研制了集成有聚二甲基硅氧烷为材料T型微通道的微混合器,压电基片上采用光刻工艺制作相互垂直叉指换能器及反射栅。待混合的两微流体采用微量进样器分别进样到声路径微通道中,依次在两叉指换能器上加RF电信号,它激发的声表面波驱动其声路径上微通道中的微流体沿微通道输运、合并,并快速混合。对2μl水-2μl蓝色染料微流体和2μl甘油-2μl蓝色染料微流体进行混合实验,结果表明,声表面波的作用可以提高微通道中微流体的混合速度,且混合程度更高。     

利用浮标和NWP风场对HY-2散射计联合定标验证

本文对海洋二号卫星微波散射计(Haiyang-2 Scatterometer,HY-2 SCAT)进行了海洋定标算法研究,并使用数值天气预报模型风场(Numerical Weather Prediction,NWP)和浮标数据对定标后反演风场进行联合验证.通过匹配2012年12月份的HY-2 SCAT反演风场、NWP风场及浮标的观测数据,共得到无降雨条件下的3112个25km分辨率的匹配数据.对匹配数据进行分析时,采用基于变量的误差分析方法能够得到比传统线性回归方法更精确的验证结果.选取在风场U、V分量进行联合验证能得到较在风速、风向上更为有利的验证结果.验证结果表明,经过海洋定标法之后的HY-2 SCAT测量后向散射系数的误差残余小于0.15dB,其反演风场与浮标及NWP数据相吻合,U、V分量相对浮标及NWP数据偏差均小于0.23m/s,验证了该定标算法的有效性及定标后反演风场的高精度.     

傅里叶红外光谱研究光敏剂5-氨基酮戊酸的光动力作用机制

本文测定了光敏剂5-氨基酮戊酸对人宫颈癌细胞HeLa光敏作用后的傅里叶红外光谱。结果显示：光敏作用后,HeLa细胞磷酸二酯基团的对称伸缩振动峰1085cm。和不对称伸缩振动峰1246cm。蓝移,强度下降;蛋白质酰胺Ⅰ带1656cm。发生蓝移,酰胺Ⅱ带1546cm^-1出现红移;CH2对称伸缩振动峰2858cm^-1,峰位蓝移2cm^-1,峰值明显减弱。结果表明：DNA、蛋白质和磷脂是5-氨墓酮戊酸光敏作用的主要靶分子。     

Studies of the sea using HF radio scatter

Radio signals of decameter wavelength resonantly scattered from waves on the sea surface are used to measure precisely the wave. length, frequency, and direction of travel of those waves. These measurements are not only important in themselves, but are also used to deduce currents, winds, and perhaps wind stress at the sea surface. Techniques for obtaining these measurements, as well as experiments to evaluate these techniques are discussed. Finally, scatter has been used to produce the first high-resolution measurements of the directional distribution of large ocean waves, measurements of ocean surface currents at ranges of 20 km, and of surface winds at ranges of 3000 km.     

ERS-1 scatterometer measurements. II. An algorithm forocean-surface wind retrieval including light winds

For pt.I see ibid., vol.36, no.2, p.603-22 (1998). An algorithm for retrieving European Remote Sensing Satellite (ERS-1) scatterometer winds, denoted the Rufenach-Bates-Tosini (RBT) algorithm, is developed and used to retrieve winds collocated within ±25 km of buoy measurements in two oceanic regions, equatorial and midlatitude. An improvement in the retrieved RBT winds over the European Space Agency (ESA) winds is due mainly to a geophysical model employing the full available wind-speed range, including the lightest winds. This model, denoted BMOD5, is tuned by using the scatterometer and buoy measurements, resulting in two different models for the midlatitude and equatorial regions. The RBT retrieved winds exhibit (1) a larger number of solutions (wind vectors) and (2) smaller biases in wind speed than the ESA wind product. The increase in the number of retrieved winds is primarily due to lighter winds employed, 0.2 m/s to 18 m/s; whereas, the ESA winds are truncated near 3 m/s. The ESA winds underestimate the highest winds significantly, by about 20%, and overestimate the lightest winds. The RBT wind bias is less than a few percent at the highest winds and a few tenths of a m/s at the lowest winds. Both algorithms retrieve 180° ambiguous directions almost as often as the true direction. Regression fits to the winds using the RBT algorithm produce standard deviations of 1 m/s and 25° near the equator for winds varying from 0.2-10 m/s and 1.2 m/s and 250 at midlatitudes for winds varying from 0.2-18 m/s, provided that the ambiguities are removed     

A Ku-band laboratory experiment on the electromagnetic bias

A uniformly valid algorithm relating the normalized (or nondimensional) sea-surface electromagnetic (EM) bias to physical variables has not yet been established. Laboratory experiments are conducted to guide model development. Simultaneous and collocated measurements of surface topography and altimeter backscattered power are made in a wind-wave facility for a wide range of wind and mechanically generated wave conditions. A small microwave footprint on the water surface is produced by a focused-beam 13.5-GHz radar system that has a high signal-to-noise ratio. Specular facets are easily identifiable, and the data show that troughs are on average better reflectors than crests. The laboratory coefficients are considerably greater than those of in situ algorithms, and when the normalized EM bias is displayed as a function of wave height skewness or wave age, laboratory and field data converge into consistent trends. A two-parameter model is proposed using a nondimensional wave height, which is computed for local winds, and a significant slope, which is computed for nonlocally generated waves. Analysis of the laboratory data shows that the normalized EM bias for mixed conditions is well modeled as a product of these two parameters     

An advanced ambiguity selection algorithm for SeaWinds

SeaWinds on QuikSCAT, a spaceborne Ku-band scatterometer, estimates ocean winds via the relationship between the normalized radar backscatter and the vector wind. Scatterometer wind retrieval generates several possible wind vector solutions or ambiguities at each resolution cell, requiring a separate ambiguity selection step to give a unique solution. In processing SeaWinds on QuikSCAT data, the ambiguity selection is "nudged" or initialized using numerical weather prediction winds. We describe a sophisticated new ambiguity selection approach developed at Brigham Young University (BYU) that does not require nudging. The BYU method utilizes a low-order data-driven Karhunen-Loeve wind field model to promote self-consistency. Ambiguity selected winds from the BYU method and standard SeaWinds processing are compared over a set of 102 revs. A manual examination of the data suggests that the nonnudging BYU method selects a more self-consistent wind field in the absence of cyclonic storms. Over a set of cyclonic storm regions, BYU performs better in 9% of the cases and worse in 20% of the cases. Overall, the BYU algorithm selects 93% of the same ambiguities as the standard dataset. This comparison helps validate both nonnudging and nudging techniques and indicates that SeaWinds ambiguity selection can be generally accomplished without nudging.     

用光谱法研究光敏剂血卟啉单甲醚对肿瘤细胞光动力作用的分子机制

测定了光敏剂血卟啉单甲醚对人宫颈癌细胞HeLa光敏作用后的傅里叶红外光谱。结果显示:光敏作用后,HeLa细胞磷酸二酯基团的对称伸缩振动峰1085cm^-1和不对称伸缩振动峰1246cm^-1蓝移,强度下降:蛋白质酰胺Ⅰ带1656cm^-1发生蓝移,酰胺Ⅱ带1546cm^-1出现红移;CH₂对称伸缩振动峰2858cm^-1,峰位蓝移2cm^-1,峰值明显减弱:细胞的蛋白质和核酸谱峰面积比值D1085/D1546降低。提示细胞中的DNA、蛋白质和磷脂结构受到损伤。结果表明:DNA、蛋白质和磷脂是血卟啉单甲醚光敏作用的主要靶分子。     

Radar backscatter from breaking waves in Gulf Stream currentconvergence fronts

Bright linear features have been observed in radar imagery taken near the Gulf Stream (GS) boundary on two separate occasions. In each case, these have been observed directly over strong current convergences. Progress has been made in understanding the origin of these signatures through simulations that incorporate environmental forcing from the winds and currents. These simulations significantly underestimate the backscatter unless wave-breaking (WB) effects are included at least approximately. Using a new, quasistatistical procedure that generalizes and quantifies earlier procedures for including WB effects, the authors have been able to successfully simulate the magnitude and behavior of these signatures. The approach combines the statistically based, composite model of radar backscatter with a deterministic feature model that relates backscatter from breaking waves to a particular geometrical model of a spilling breaker. This is accomplished using localized criteria, defined by local wave crest acceleration, to determine the probability of breaking, and by extending the feature model so that its unknown parameters may be evaluated directly from wave-current interaction calculations. The new approach provides an estimate of the critical crest acceleration of a potentially breaking wave, as a function of wind speed, that agrees with independent measurements     

Laboratory study of polarized scattering by surface waves atgrazing incidence. I. Wind waves

Laboratory measurements of Ku-band scattering at grazing incidence are presented. This study was motivated by the need to understand the processes which significantly contribute to scattering at grazing incidence. A dual polarized (VV, HH) coherent pulsed Ku-band scatterometer with good temporal resolution (3 ns) was used to obtain Doppler spectra and the absolute cross-section of scattered signals for grazing angles from 6-12°, and winds in the range 2-12 m/s. Wire wave gauges were used to measure the wind-wave field. Measurements of the first few moments of the Doppler spectra (cross-section, central frequency and bandwidth) showed that the data separated into two groups. The first grouping corresponded to HH scattering in the upwind look direction, and was clearly associated with scattering from the dominant gravity wind-waves. The second grouping corresponded to HH scattering in the downwind look direction, and all VV scattering, and was consistent with Bragg scattering from free higher frequency waves. This classification of the electromagnetic scattering was consistent with comparisons of direct and Doppler measurements of the kinematics of the surface wave field. The electromagnetic classification was also consistent with asymmetries in the wave field which increased with increasing wind speed     

Assimilation of altimeter significant wave height into a third-generation global spectral wave model

Data from three different altimeters (Topex/Poseidon, Jason-1, and European Remote Sensing Satellite 2) have been assimilated in a third-generation global spectral wave model forced by winds observed by scatterometer onboard QuikSCAT. Two different approaches of assimilation have been discussed. In the first approach, a simple scaling has been used to generate wave spectrum from altimeter-derived significant wave heights for assimilation in the model. In the second approach, the influence of altimeter observation has been spread to nearby grid points. Assimilation has been carried out every 6 h for five days. After the expiry of the assimilation phase, the model has been run in pure hindcast mode. Assimilation experiments have been carried out for the months of September and December 2002. Impact of assimilation has been found to be quite high in the Indian Ocean. It has been also found that the model is able to retain the memory of assimilation for a period of two and a half days as far as global ocean is concerned. This memory is more for the Indian Ocean. The wave spectrum generated by the model in the hindcast mode has been validated against the buoy-observed wave spectrum in the high sea conditions. The more significant impact has been seen in the case of altimeter track in the vicinity of the buoy.     

Statistical problems of wind-generated gravity waves arising inmicrowave remote sensing of surface winds

The basic geometric features of a developed sea surface affecting the accuracy of wind speed measurements by satellite instruments are reviewed. Based on Seasat scatterometer, Geosat altimeter, and DMSP-SSM/I (Defense Meteorological Satellite Program Special Sensor Microwave/Imager) observations collocated with buoy data, error trends in the satellite winds are shown to be correlated with various measures of wave development. These trends are explained by examining the RMS wave slope of energy-containing waves which, directly or indirectly, affects all microwave techniques. Statistics of temporal-spatial rates of steep and breaking waves (affecting the scatterometer and radiometer measurements) are derived and compared with field observations