Modifying the ionosphere with intense radio waves

The ionospheric modification experiments provide an opportunity to better understand the aeronomy of the natural ionosphere and also afford the control of a naturally occurring plasma, which will make possible further progress in plasma physics. The ionospheric modification by powerful radio waves is analogous to studies of laser and microwave heating of laboratory plasmas (20). " Anomalous" reflectivity effects similar to the observed ionospheric attenuation have already been noted in plasmas modulated by microwaves, and anomalous heating may have been observed in plasmas irradiated by lasers. Contacts have now been established between the workers in these diverse areas, which span a wide range of the electromagnetic spectrum. Perhaps ionospheric modification will also be a valuable technique in radio communications.     

Controlled stimulation of magnetospheric electrons by radio waves: experimental model for lightning effects

Magnetospheric electrons precipitated by ground-based coded very low frequency radio transmissions have been detected by rocket measurement of bremsstrahlung x-rays, caused by impact of the electrons with the upper atmosphere. The direct correlations obtained between the very low frequency signals and the x-rays demonstrate the limits of sensitivity required and indicate that this remote sensing technique would be useful for future study of very low frequency effects induced by single lightning strokes.     

Direct-current nanogenerator driven by ultrasonic waves

We have developed a nanowire nanogenerator that is driven by an ultrasonic wave to produce continuous direct-current output. The nanogenerator was fabricated with vertically aligned zinc oxide nanowire arrays that were placed beneath a zigzag metal electrode with a small gap. The wave drives the electrode up and down to bend and/or vibrate the nanowires. A piezoelectric-semiconducting coupling process converts mechanical energy into electricity. The zigzag electrode acts as an array of parallel integrated metal tips that simultaneously and continuously create, collect, and output electricity from all of the nanowires. The approach presents an adaptable, mobile, and cost-effective technology for harvesting energy from the environment, and it offers a potential solution for powering nanodevices and nanosystems.     

Rotating spiral waves created by geometry

The Belousov-Zhabotinsky reagent and numerical simulations were used to show that under high-frequency stimuli, rotating spiral waves can be initiated in a homogeneous excitable medium in the vicinity of domain boundaries or inexcitable barriers with sharp corners.     

Wind velocities on venus: vector determination by radio interferometry

To determine the wind directions and speeds on Venus, as each Pioneer probe fell to the surface we tracked its motion in three dimensions using a combination of Doppler and long-baseline radio interferometric methods. Preliminary results from this tracking, coupled with results from test observations of other spacecraft, enable us to estimate the uncertainties of our eventual determinations of the velocity vectors of the probes with respect to Venus. For altitudes below about 65 kilometers and with time-averaging over 100-second intervals, all three components of the velocity should have errors of the order of 0.3 meter per second or less.     

Blood pressure responses of wild giraffes studied by radio telemetry

Blood pressure was telemetered from transducers chronically implanted in the carotid arteries of two adult, wild, male giraffes captured and released near Kiboko, Kenya. Cerebral perfusion pressure ranged from 280/180 mm-Hg while the animal was lying with its head on the ground to 125/75 mm-Hg when it was standing erect; it varied between these levels during spontaneous activity such as walking, grazing, and running.     

Earth's free oscillations excited by the 26 December 2004 Sumatra-Andaman earthquake

At periods greater than 1000 seconds, Earth's seismic free oscillations have anomalously large amplitude when referenced to the Harvard Centroid Moment Tensor fault mechanism, which is estimated from 300- to 500-second surface waves. By using more realistic rupture models on a steeper fault derived from seismic body and surface waves, we approximated free oscillation amplitudes with a seismic moment (6.5 x 10(22) Newton.meters) that corresponds to a moment magnitude of 9.15. With a rupture duration of 600 seconds, the fault-rupture models represent seismic observations adequately but underpredict geodetic displacements that argue for slow fault motion beneath the Nicobar and Andaman islands.     

人工智能对龙井茶等级识别研究

应用电子鼻、电子舌技术对6个等级龙井茶进行识别研究。检测数据通过主成分分析(PCA)与判别因子分析(DFA),确定龙井茶等级识别最佳传感器阵列组合。结果表明,以S2-100Hz金电极、S3-1Hz钯电极、S4-1Hz钨电极、S6-100Hz银电极为传感器阵列,建立龙井茶汤智舌模型;以S1、S2、S4、S5、S6为传感器阵列,建立龙井茶汤智鼻模型;以S2、S4、S5、S6为传感器阵列,建立龙井干茶智鼻模型,将智舌、智鼻检测方法结合形成的人工智能识别龙井茶等级的方法具有极高的辨识能力,能够快速有效地判别龙井茶样等级。     

人工地层冻结冻土自然解冻与强制解冻实测分析

通过自然解冻和强制解冻原位试验,得出冻土自然解冻和强制解冻温度变化规律。冻土自然解冻速度非常缓慢,强制解冻能显著的加快冻土解冻速度。对于多排管冻结形成的大体积冻土,可利用强制解冻加快冻土解冻速度,达到及时跟踪注浆,更好的控制融沉目的。     

Gravitational inconsistency in the lunar theory: confirmation by radio tracking

When range and Doppler observations of space probes near or on Moon are reduced by use of a lunar ephemeris calculated from the Brown lunar theory, residuals as large as 440 meters in position and 1.5 millimeters per second in velocity are observed. When the calculations are repeated with use of LE 5, the integrated lunar ephemeris described (1), the residuals are greatly reduced.     

Navigation of single homing pigeons: airplane observations by radio tracking

Navigation of homing pigeons was investigated by tracking their homeward flights from a light airplane. Released on successive days from a single training point 35 miles (56 kilometers) from home, individual pigeons, each carrying a transmitter, were repeatedly tracked back to theirloft. No two tracks covered the same ground for even short distances, yet all tracks were within 10 miles of a straight line. Results from further releases north and south of the training point suggest that pigeons often use three methods in sequence to find home: compass orientation, bi-coordinate navigation, and orientation by familiar landmarks.     

Photosynthetic light harvesting by carotenoids: detection of an intermediate excited state

We present the first direct evidence of the presence of an intermediate singlet excited state (Sx) mediating the internal conversion from S2 to S1 in carotenoids. The S2 to Sx transition is extremely fast and is completed within approximately 50 femtoseconds. These results require a reassessment of the energy transfer pathways from carotenoids to chlorophylls in the primary step of photosynthesis.     

Excitation of surface waves by events in southern algeria

Surface-wave magnitudes (M(8)) of 4.1 and 3.2 are determined for two events in southern Algeria. The corresponding body-wave magnitudes (m(b)) are 5.8 and 4.9, respectively. The surface waves from these events are much smaller than would be expected from most earthquakes of comparable body-wave magnitudes, which fact suggests that these waves were generated by underground explosions.     

室内水生动物对蓝藻生长的抑制效果

在室内模拟小水体中,开展了不同密度尼罗罗非鱼和鲢鱼抑制蓝藻生长的对比试验.结果表明:尼罗罗非鱼和鲢鱼对水体中蓝藻绿藻过量增长均有不同程度的抑制作用,其中尼罗罗非鱼抑制消除蓝藻的效果优于鲢鱼,且尼罗罗非鱼的密度越高抑制消除蓝藻的速度越快;尼罗罗非鱼对水体中营养盐水平消除无明显贡献,但能有效提高水体的透明度,降低水体的pH值.     

人工快速渗滤系统去除氨氮研究

在土地处理的基础上,运用人工快速渗滤系统改善微污染河水水质,研究了不同温度和不同深度处3种滤料对氨氮的去除效果。结果表明,人工快速渗滤系统具有良好的去除氨氮能力,氨氮的去除率随着有效粒径的增大而减小,但影响不明显;去除效果主要在表层50 cm处;温度对去除效果影响不明显,夏季和冬季的去除率基本一致,氨氮的去除率主要受溶解氧限制。人工快速渗滤系统可以用于去除微污染河水中的氨氮。     

人工生态系统修复砷污染土壤的应用研究

通过在某雄黄矿区的野外调查,并结合实验室分析,证实蜈蚣草和五节芒不仅能很好地生长在较高浓度砷污染土壤上,而且还能大量地积累砷到其体内,表现出较强的富集能力,尤其是蜈蚣草。砷在蜈蚣草体内的分布表现为羽片>茎秆;而砷在五节芒体内的分布表现为茎秆>羽片。盆栽试验表明,两个品种的油菜(湘杂油1号和湘杂油15号)对砷也有一定的耐性和富集能力。当土壤砷含量小于108.59 mg/kg时,油菜能正常生长,且生物量很大,而当土壤砷含量达到208.83 mg/kg时,砷会对油菜产生毒害作用,其生长速度较慢,对砷的富集能力也减小。因此,在砷污染区可以利用蜈蚣草、五节芒和油菜等具有较高抗砷能力和能大量累积砷的植物构建一个可修复砷污染的人工生态系统,从而更有效地修复砷污染的土壤。     

人工植被坡面产流问题研究进展

随着山坡水文学的发展，人工植被坡面产流问题的研究在水文学领域中具有十分重要的意义，且受到越来越广泛的重视．分析了人工植被坡面径流的研究现状，并简要论述了坡面产流研究的若干成果及未来展望。