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61.
M. J. Pierce J. S. Jurcevic D. Crabtree 《Monthly notices of the Royal Astronomical Society》2000,313(2):271-280
We present CCD photometry of red supergiant long-period variables (LPVs) in the Per OB1 association, the Large Magellanic Cloud (LMC) and M33. The photometry was obtained in the Kron–Cousins R and I bandpasses and in a narrow bandpass ( λ 0 =8250 Å, FWHM=300 Å) chosen to avoid TiO bands in the spectral energy distribution of the LPVs. Because the strength of the TiO bands varies greatly with temperature, which varies with the phase of an LPV, avoiding TiO reduces the amplitude of the photometric variations seen in LPVs. The result is a lower dispersion and a well defined period–luminosity (PL) relation.
For the LMC sample we find an rms dispersion of 0.27 mag in the narrow-band PL relation and slightly larger dispersions for the LPVs in Per OB1 and M33. This dispersion is comparable to that of the Cepheid PL relation at similar wavelengths. Adopting a distance modulus of 18.5±0.1 mag for the LMC, we obtain distance moduli of 11.68±0.15 mag for Per OB1 and 24.85±0.13 mag for M33. These distances agree well with those based on main sequence fitting for Per OB1 and the Cepheid distance for M33. Since LPVs are ∼ 5 times more common than Cepheids and have a well defined PL relation, LPVs provide a promising method for estimating Galactic and extra galactic distances. 相似文献
For the LMC sample we find an rms dispersion of 0.27 mag in the narrow-band PL relation and slightly larger dispersions for the LPVs in Per OB1 and M33. This dispersion is comparable to that of the Cepheid PL relation at similar wavelengths. Adopting a distance modulus of 18.5±0.1 mag for the LMC, we obtain distance moduli of 11.68±0.15 mag for Per OB1 and 24.85±0.13 mag for M33. These distances agree well with those based on main sequence fitting for Per OB1 and the Cepheid distance for M33. Since LPVs are ∼ 5 times more common than Cepheids and have a well defined PL relation, LPVs provide a promising method for estimating Galactic and extra galactic distances. 相似文献
62.
本文在考察了节理化岩体的断裂力学特征的基础上,结合现代分形几何原理,建立起追踪裂纹裂分形模型,对不连续岩体的断裂韧性的分形效应进行了深入研究,并通过压剪试验得到难。 相似文献
63.
The organic composition and organic‐inorganic interaction in paper mill sludge (PS) solvent extracts (hexane, ethyl acetate, acetone and ethanol) and humic fractions, humic acid (HA) and humin (HU) were studied by electron paramagnetic resonance spectroscopy (EPR), proton and carbon‐13 nuclear magnetic resonance spectroscopy (1H NMR; 13C NMR), Fourier‐transformed infrared spectroscopy (FTIR), and ultraviolet‐visible spectroscopy (UV‐vis). The strategy of fractionating the PS, sequentially, with organic solvents of increasing polarity is a reliable analytical procedure for humic substance sample separation because it results in more purified fractions. FTIR, 1H NMR and 13C NMR results showed that hexane extract consisted mainly of aliphatic hydrocarbon structures. Their contents in the extracts decreased as the polarity of the extracting solvent increased and the content of oxygen functional groups increased. Carboxylic and carboxylate functional groups were found in the acetone extract, and ester and ether functions were predominantly found in the ethanol extract. EPR spectra revealed some Fe3+ complexes with rhombic structure (g1 = 4.3; g2 = 9.0) in the humic fractions and in all solvent extracts, except hexane. Quasi‐octahedral Fe3+ complexes (g = 2.3; ΔHpp ≤ 400 G) were found in the HU fraction and in the acetone extract. The organic free radical content in the HA fraction was higher than the non‐fractionated PS sample and HU fraction. 相似文献
64.
从冷科1井下部地层的归属探讨柴达木盆地成盆时间 总被引:3,自引:1,他引:3
冷科1井是近年来柴达木盆地北缘最重要的一口科学探索井.因该井首次发现了巨厚的新地层,所以对该井的4 666~5 200 m地层划分存在较大争议.前人主要依据孢粉资料把冷科1井4 666~5 200 m层段归属为下侏罗统,也有人依据从该段发现的海相化石碎片认为该段为石炭系.本文从岩性组合、古生物特征、地震剖面、测井电性及水介质特征等多方面对该层段进行了分析,否定了该段为下侏罗统和石炭系的可能,认为该段为上三叠统.该研究改变了过去柴达木盆地始于早侏罗世的观点,指出柴达木盆地起始于晚三叠世零星分布的断陷沉积. 相似文献
65.
南海海平面高度年循环的特征 总被引:10,自引:0,他引:10
根据 TOPEX/ POSEIDON-ERS高度计提供的海平面高度异常资料和并行海洋气候模式(POCM)模拟海平面高度资料,分析了南海海平面高度年循环特征。结果表明:l月,3月和5月海平面高度的异常值分别与7月,9月,11月的异常值相反。l月(7月),深水海区与吕宋海峡的海平面高度为负(正)异常,在大部分陆架区和南海的西和南部,海平面高度为正(负)异常。在3月(9月),除海平面高度异常的量级已减少,且较小的SSH正异常(负异常)出现在南海的中部以外,海平面高度异常的分布型与 1月(7月)类似; SSH的年循环的最大振幅出现在吕宋岛的西北海域;风的季节变化是南海SSH季节变化的主要原因。 相似文献
66.
J. Perbos P. Escudier F. Parisot G. Zaouche P. Vincent Y. Menard F. Manon G. Kunstmann D. Royer L. -L. Fu 《Marine Geodesy》2003,26(3):147-157
On 7 December 2001, Jason-1 was successfully launched by a Boeing Delta II rocket from the Vandenberg Air Force Base, California. The Jason-1 satellite will maintain the high accuracy altimeter service provided since 1992 by TOPEX/Poseidon (T/P), ensuring the continuity in observing and monitoring the Ocean Dynamics (intraseasonal to interannual changes, mean sea level, tides, etc.). Despite one-fourth the mass and power, the Jason-1 system has been designed to have basically the same performance as T/P, measuring sea surface topography at a centimetric level. This new CNES/NASA mission also provides near real-time data for sea state and ocean forecast. The first two months of the Jason-1 mission have been dedicated to the assessment of the overall system. The goals of this assessment phase were:
1. To assess the behavior of the spacecraft at the platform and payload levels (Jason-1 being the first program to call on the PROTEUS versatile multimission platform for Low and Medium Earth Orbit Missions developed in partnership between Alcatel Space and CNES);
2. To verify that platform performance requirements are met with respect to Jason-1 requirements;
3. To verify that payload instruments performance requirements evaluated at instrument level are met;
4. To assess the performance of the Jason-1 Ground System.
This article will display the main outputs of the assessment of the system. It will demonstrate that all the elements of the onboard and ground systems are within the specifications. Provision of data to the Jason-1 Science Working Team started at the end of March 2002. This is the goal of a six-month phase after closure of the initial assessment phase to derive the error budget of the system in terms of altimetry user products. 相似文献
1. To assess the behavior of the spacecraft at the platform and payload levels (Jason-1 being the first program to call on the PROTEUS versatile multimission platform for Low and Medium Earth Orbit Missions developed in partnership between Alcatel Space and CNES);
2. To verify that platform performance requirements are met with respect to Jason-1 requirements;
3. To verify that payload instruments performance requirements evaluated at instrument level are met;
4. To assess the performance of the Jason-1 Ground System.
This article will display the main outputs of the assessment of the system. It will demonstrate that all the elements of the onboard and ground systems are within the specifications. Provision of data to the Jason-1 Science Working Team started at the end of March 2002. This is the goal of a six-month phase after closure of the initial assessment phase to derive the error budget of the system in terms of altimetry user products. 相似文献
67.
A three-dimensional numerical model is developed and used to study the coastal upwelling processes and corresponding seasonal changes in the sea level along the west coast of India. The upwelling and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. The model is designed to represent coastal ocean physics by resolving surface and bottom Ekman layers as realistically as possible. The prognostic variables are the three components of the velocity field, temperature, salinity and turbulent energy. The governing equations together with their boundary conditions are solved by finite-difference techniques. Experiments are performed to investigate sea level fluctuations associated with the thermal response and alongshore currents of the coastal waters. The model is forced with mean monthly wind stress forcing of January, May, July and September representing northeast monsoon and different phases of the southwest monsoon. It is known from the observational study that the upwelling process reaches to the surface waters by May along the coastal waters of the extreme southwest peninsular region. The process is more intense in July compared to May and September and its strength decreases from south to north. However, during the northeast monsoon season, which is represented by January wind stress forcing in the model, downwelling is simulated along the coast. The model simulations of the coastal response are compared with the observations and are found to be in good agreement. The maximum computed vertical velocity of about 2.0 2 10 -3 cm s -1 is predicted in July in the southern region off the coast. 相似文献
68.
The improvement on the calculation of anti-Stokes energy transfer rate is studied in the present work. The additional proportion coefficient between Stokes and anti-Stokes light intensities of quantum Raman scattering theory as compared with the classical Raman theory is introduced to successfully describe the anti-Stokes energy transfer. The theoretical formula for the improvement on the calculation of anti-Stokes energy transfer rate is derived for the first time in this study. The correctness of introducing coefficient exp{ΔE / kT} from well-known Raman scatter theory is demonstrated also. Moreover, the experimental lifetime measurement in Er0.01YbxY1 - 0.01 - xVO4 crystal is performed to justify the validity of our important improvement in the original phonon-assisted energy transfer theory for the first time. 相似文献
69.
Raúl Prellezo Paolo AccadiaJesper L. Andersen Bo S. AndersenErik Buisman Alyson LittleJ. Rasmus Nielsen Jan Jaap PoosJeff Powell Christine Röckmann 《Marine Policy》2012,36(2):423-431
The lessons learned from a review of thirteen existing European bio-economic models used in the evaluation of EU policies are presented. How these models compare and differ in terms of their biological and economic components, the integration between the components, which indicators are selected and how they are used, are described and analysed. The article concludes that the multitude of construction differences reflects the necessity of adapting the modelling approach to answer different questions. Since real life questions in fisheries are so diverse, answering them requires a diversity of models. 相似文献
70.
本文介绍了长江口区水文泥沙概况,举例说明了SSA1-1型声水位计在崇头潮位站比测试验和投产应用情况,结果表明该水位计是收集长江口区潮位资料较理想的仪器。 相似文献