Photometric variability and evolutionary status of the supergiant with an infrared excess HD 179821=V1427 aquilae

We present new results of our UBV photometry for HD 179821=V1427 Aql, an F supergiant with an infrared excess, from 2000 to 2008. The semiregular low-amplitude (ΔV = 0_. ^m 05−0_. ^m 20) photometric variability of the star with a cycle period from 130 to 200 days is caused by pulsations, along with the instability of a variable stellar wind. V1427 Aql also exhibits a long-term trend in the brightness and colors that is probably attributable to a change in the stellar temperature as a result of mass loss episodes, which cause variations in the continuum formation level. We present the results of our JHKLM photometry for V1427 Aql in 1992–2008. We trace the trend in the near-infrared brightness, which agrees with the long-term variability in the V band. Based on broadband photometry, we have determined the color excess for V1427 Aql: E(B−V) = 0.7. Based on low-resolution spectroscopy, we have estimated the stellar temperature and revealed variability of the Hα line caused by a change in the contribution from the emission component. The hypotheses of whether the star belongs to post-AGB objects or to massive yellow hypergiants are discussed.     

区域气候模式REMO对中国气温和降水模拟能力的评估

采用泰勒图和偏差分析等统计方法,评估分析了德国区域气候模式（REMO）对中国1989-2008年气温和降水的模拟能力。结果表明：REMO气温模拟值与观测值空间相关系数为0.94,降水空间相关系数较低（0.42）,气温模拟结果明显优于降水;从空间偏差上看,在中国大部分地区,REMO模拟的气温高于观测值,偏差在±4℃以内,青藏高原整体有明显的-4～-2℃的冷偏差;模拟的降水值则高于观测值,空间偏差分布较均匀,中国大部分地区偏差在±300 mm之内;除青藏高原、华南和西南地区外,REMO能较准确地反映出中国气温和降水的空间分布特征,其中华北和东北地区模拟效果最好;REMO对夏季气温和冬季降水的模拟能力相对较好;REMO在地形起伏较大地区的模拟能力有待提高。     

Geochronology and paleomagnetism of mafic igneous rocks in the Olenek Uplift, northern Siberia: Implications for Mesoproterozoic supercontinents and paleogeography

We present a new, reliably dated Mesoproterozoic paleopole for Siberia, based on a combined geochronological and paleomagnetic study of mafic rocks within the Mesoproterozoic Sololi Group of the Olenek Uplift in northern Siberia. Ion microprobe (SHRIMP) U–Pb analysis yields crystallisation ages of 2036 ± 11 Ma for zircon from a basement granite and 1473 ± 24 Ma for baddeleyite from a large dolerite sill within the Kyutingde Formation. The baddeleyite result indicates that the lower Sololi Group is significantly older than was suggested by previous K–Ar results. Paleomagnetic analysis of the dolerite sill and related mafic intrusive rocks yields a paleopole at 33.6°N, 253.1°E, A₉₅ = 10.4°. A positive baked-contact test between the Kyutingde sill and sedimentary country rocks shows that the magnetisation is primary. Comparison of this paleopole with coeval results for Laurentia provides a revised reconstruction between Siberia and Laurentia, and implies that these two continents were parts of a single Mesoproterozoic supercontinent since at least 1473 Ma. We argue that Siberia, Laurentia, and Baltica belonged to the same supercontinent between 1473 Ma and mid-Neoproterozoic time.     

Pressure solution creep under cyclic loading

Pressure solution creep was studied on sodium chloride, calcium carbonate and ammonium nitrate in respective saturated aqueous solutions under static loading and cyclic unloading. Ball indentation and powder compaction curves show that each transition from static to cyclic regime produces an increase—sometimes manifold—in creep rate which lasts over the whole time of cyclic impact. After returning to static regime, the initial creep rate reappears. Over longer-term tests, both in static and cyclic regime, the creep gradually slows down. Increasing impact frequency enhances the effect. Any noticeable changes in strain rate are absent in a pure inert medium (paraffin oil). Possible mechanisms of the cyclic unloading effect are discussed.     

Petroleum surface oil seeps from a Palaeoproterozoic petrified giant oilfield

Early Palaeoproterozoic rocks from the Onega Basin in Russian Fennoscandia contain evidence for substantial accumulation and preservation of organic matter (up to 75 wt% total organic carbon) with an estimated original petroleum potential comparable to a modern supergiant oilfield. The basin contains a uniquely preserved petrified oilfield including evidence of oil traps and oil migration pathways. Here, we report the discovery of the surface expression of a migration pathway, along which petroleum was flowing from the sub-surface. This surface oil seep, the first occurrence ever reported from the Palaeoproterozoic, appears as original bitumen clasts redeposited in Palaeoproterozoic lacustrine turbidites. The δ¹³C_org of clastic pyrobitumen ranges between −35.4 and −36.0‰ ( n  = 14), which is within the range of interbed- and vein-trapped fossil oil (−46 and −24‰), suggesting similar source. Biogenic organic matter, whose isotopic composition was modified during thermal maturation, is the likely source for the migrated hydrocarbon.     

Infrared observations of the star R Cas

We present our JHKLM photometry for R Cas performed during 1988–2000. The pulsation period of R Cas is $P \approx 429\mathop .\limits^d 6$ , with the maximum IR brightness lagging behind the maximum visual brightness by ～0.2 P. The amplitude of light variations appreciably decreases with increasing wavelength at λ≤3 μm. At λ>3 μm, this decrease virtually ceases. There is a step on the ascending branch of IR JHK brightness. The K-L color index increases linearly with K magnitude: $K - L = 0.304K + 1\mathop .\limits^m 20$ . The color temperature dependence, T _K-L =f(K), is also linear: T _K?L = ?622K + 1100 K. In going from minimum to maximum, the K flux (as well as the bolometric flux) from the star and its color temperature T _K-L increase by a factor of ～2.2 and ～1.3, respectively.     

Multipath mitigation by conventional antennas with ground planes and passive vertical structures

An antenna ground plane (GP) plays a major role in the mitigation of multipath coming from underneath the antenna. A distinct trend in user antenna size and weight reduction has been observed during recent years. With this focus in mind, an overview of conventional flat conductive and impedance GP is provided. Results of modern developments of passive vertically stacked structures are discussed. The possibility of obtaining a reasonable level of multipath mitigation with vertical structures of several centimeters is shown.     

A multiscale method for distributed parameter estimation with application to reservoir history matching

A method for multiscale parameter estimation with application to reservoir history matching is presented. Starting from a given fine-scale model, coarser models are generated using a global upscaling technique where the coarse models are tuned to match the solution of the fine model. Conditioning to dynamic data is done by history-matching the coarse model. Using consistently the same resolution both for the forward and inverse problems, this model is successively refined using a combination of downscaling and history matching until model-matching dynamic data are obtained at the finest scale. Large-scale corrections are obtained using fast models, which, combined with a downscaling procedure, provide a better initial model for the final adjustment on the fine scale. The result is thus a series of models with different resolution, all matching history as good as possible with this grid. Numerical examples show that this method may significantly reduce the computational effort and/or improve the quality of the solution when achieving a fine-scale match as compared to history-matching directly on the fine scale.     

Magmatic sources and geodynamics of the early Mesozoic Northern Mongolia-Western Transbaikalia rift zone

The Northern Mongolia-Western Transbaikalia rift zone is the largest Mesozoic riftogenic structure in eastern Asia and extends for a distance of more than 1200 km. The zone consists of depressions and grabens, which were formed between 233 and 188 Ma and are filled with basaltic and basalt-comendite (bimodal) volcanic associations accompanied by numerous peralkaline granite massifs. Geochemical and isotope (Sr, Nd, and Pb) studies showed that mantle and crustal sources contributed to the formation of the magmatic rocks of the rift zone. The basalts were formed from incompatible element-enriched mantle sources. Geochemical and isotope-geochemical data suggest that the peralkaline salic rocks (comendites and peralkaline grantoids) and basalts are genetically related and were formed by the fractionation of a common parental magma. In addition, the magmatic associations contain peralkaline granites and comendites whose isotope signatures indicate their formation through the crustal contamination of derivatives of basaltic melts. The rift zone has arisen during the formation of the Mongolia-Transbaikalia zoned magmatic area in a complex geodynamic setting, combining collision in the Mongolia-Okhotsk suture with a mantle plume impact. The rift zone occupies the northern periphery of the area, being controlled by the Northern Mongolia-Transbaikalia fault system, which marks the boundaries (sutures) of large terranes in the lithosphere. Asthenospheric traps beneath suture boundaries served as pathways for the penetration of a mantle plume into the upper lithosphere, thus playing an important role in the localization of the riftogenic processes.