Giant Vibrations in Dip

This work reports the discovery of solar-type oscillations in thegiant star Hydrae.     

Accelerator mass spectrometry radiocarbon dating of 1994 Lake Winnipeg cores

Conventional radiocarbon dating of Lake Winnipeg core samples has produced erroneously old ages due to the incorporation of pre-Quaternary carbon derived from carbonaceous rocks, soils and sediments in the watershed, as well as a hard-water effect resulting from leaching of calcareous rocks and soils. To circumvent these problems and develop a reliable chronology for the Lake Winnipeg core series, a total of 64 samples from the Lake Winnipeg core series were processed to isolate well preserved macrofossils suitable for Accelerator Mass Spectrometry (AMS) radiocarbon dating. Here we report six radiocarbon ages derived from plant macrofossils and ostracodes, and reconstruct aspects of the depositional environment of each sample based on the associated macrofossil assemblage.     

Lagrangian Solution of Dynamo Equations and Path Integrals

We discuss an explicit solution of the Cauchy problem for induction equation and suggest its generalization for equations of ²-dynamo. These solutions are based on concepts of multiplicative, Wiener path, and stochastic integrals. Obtained explicit solution can be useful as a tool in investigations of a dynamo with fluctuating helicity.     

A method of searching for radial velocity anomalies in the lower mantle using interfering signals

Radial velocity anomalies in the lower mantle that give rise to triplications in the travel-time curve for short-periodP waves will produce arrivals havingdT/d values that differe by roughly 0.2–0.5 s/deg. The first two arrivals associated with such triplications will be separated by less than one second over a distance range of 4°–10° they may not, therefore, be separable visually on single seismograms, so that their presence can only be inferred from some measurable property that depends on their mutual interference. If there are lateral variations in the regions of anomalous velocity gradients, the interfering signals will also have different azimuths of arrival. Using two synthetic wavelets we have investigated the effect of interference on bothdT/d and azimuth measurements at the Yellowknife Array. We found that if the interfering pulses have a dominant frequencyv, there is a range of time separations (0.30/v0.55/v) over which the measureddT/d and azimuth values may fluctuate by much more than the differences indT/d and azimuth between the interfering signals. We have evaluated the following empirically defined functions for three different primary signals, and for three different relative amplitudes of the interfering signals:f (t), the drift function, which expresses how the measured slownesses,p, and azimuths, , differ from the slownesses and azimuths of the primary wavelets; f(), the range function, which describes the behaviour of the upper and lower bounds ofp and as a function of the difference in arrival times of the signals, andf , studied the properties of these functions, and have outlined how these properties provide criteria based on the numerical and statistical characteristics of the arrival vectors, and on the waveform of the signal that will enable small radial velocity anomalies to be more clearly delineated.Contribution No. 863 from the Earth Physics Branch.     

A study on the long term periodicities among the X‐ray binaries: Two new superorbital periods

Long term behaviours of a few selected X‐ray binaries are studied on the basis of RXTE/ASM archive covering a period of ∼13 years of continuous X‐ray data. Two new superorbital periods seem to be revealed for the GX354‐0 and X Persei systems as 8.7 years and 345 days, respectively. Although the X Persei system has two strongest peaks in its power density spectrum at 15.7 years and at 345 days, the latter is much more plausible. The GX354‐0 system also has few additional periodicities appeared in different time intervals (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Biodegradation and environmental behavior of biodiesel mixtures in the sea: An initial study

Biodiesel, a mixture of fatty acid methyl esters (FAMEs) derived from animal fats or vegetable oils, is rapidly moving towards the mainstream as an alternative source of energy. However, the behavior of biodiesel, or blends of biodiesel with fossil diesel, in the marine environment have yet to be fully understood. Hence, we performed a series of initial laboratory experiments and simple calculations to evaluate the microbial and environmental fate of FAMEs. Aerobic seawater microcosms spiked with biodiesel or mixtures of biodiesel and fossil diesel revealed that the FAMEs were degraded at roughly the same rate as n-alkanes, and more rapidly than other hydrocarbon components. The residues extracted from these different microcosms became indistinguishable within weeks. Preliminary results from physical-chemical calculations suggest that FAMEs in biodiesel mixtures will not affect the evaporation rates of spilled petroleum hydrocarbons but may stabilize oil droplets in the water column and thereby facilitate transport.     

一类信号恢复问题的投影迭代硬阈值算法

本文给出了基于L₀模求解该问题的非凸模型,借助于稀疏正则化方法来克服问题的不适定性。该模型利用紧小波框架对信号进行稀疏逼近,并利用L₀模度量稀疏性。提出了求解该模型的投影迭代硬阈值算法,并证明了算法的全局收敛性。该算法每一步都有闭式解,计算过程简洁高效。数值实验表明,方法在重建信号的视觉质量和量化指标方面均优于所对比的pFISTA方法。     

矿山井下罗盘仪测量数据处理程序设计

在金属矿山井下测量生产实践中,经常会遇到罗盘仪测量计算数据处理问题。由于其计算公式较为复杂,计算量大,手工计算不仅烦琐,而且常常出错。因此,本设计针对以上问题应用Visual Basic6.0编程语言,建立相应的数学模型,编写矿山井下测量数据处理程序。程序采用多重窗体界面,界面清晰、易懂。程序对输入数据进行自动化处理,输出数据格式符合常用测绘软件(南方CASS)数据格式要求,能减轻金属矿山地采测量工作者内业处理数据负担,提高工作效率,具有一定的广泛性、实用性。     

p-mode Oscillations of α Cen A

Models of Cen A & B have been computed using the masses determinedby Pourbaix et al. (2002) and the data derived from the spectroscopicanalysis of Neuforge and Magain (1997). The seismological dataobtained by Bouchy and Carrier (2001, 2002) do help improveour knowledge of the evolutionary status of the system. All the constraintsare satisfied with a model which gives an age of about 6 Gyr for the binary.     

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