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Vassilios N. Manimanis Chloe Vamvatira-Nakou Panagiotis G. Niarchos 《Astrophysics and Space Science》2009,323(2):115-121
A photometric analysis of the short-period Algol eclipsing binary system BF Velorum based for the first time on complete BVRI
CCD light curves is presented. The new photometric solution obtained with the Wilson-Devinney program reveals that BF Vel
is a near-contact semi-detached system with its secondary component filling its Roche lobe. Moreover, we discovered pulsations
of one member of the binary system, the analysis of which shows main frequencies of 44.9386 and 33.6731 cycles/day. Absolute
elements of the system were calculated, and the evolutionary status of its members was estimated.
相似文献
124.
以研究区1∶10 000DEM和DLG数据为基础,分别提出基于DLG数据和DEM数据的精细化处理方法,并对比分析了最近邻域法、双线性内插法以及三次卷积法三种重采样方法对DEM精细化处理效果的影响,结果表明:双线性内插法在时间效率、数据精度以及图像效果方面均适中,故决定采用双线性内插法将研究区5m格网DEM数据通过重采样生成为2m格网DEM数据,最后通过可视化和检查点法验证了精细化处理的精度均满足相关要求。相关研究成果可为地形特征等数据的提取提供精度较高的基础数据。 相似文献
125.
文章利用数字高程剖面将青藏高原东缘分为4个大尺度地貌单元,即青藏高原地貌区、龙门山高山地貌区、山前冲积平原区(成都盆地)和四川盆地东部隆起区。根据数字高程剖面中的最高海拔高程点剖面与最低海拔高程点剖面之间的高差,定量计算了该地区河流下切深度;结合成都盆地岷江最古老冲积扇沉积物提供的青藏高原东缘河流形成的时间(3.6MaB.P.),定量计算了河流下切速率为1.29mm/a;在约束局部侵蚀基准面和气候变化对河流下切速率控制作用的基础上,建立了青藏高原东缘河流下切速率与表面隆升速率之间的定量关系,结果表明河流下切速率约为表面隆升速率的4倍。基于龙门山在表面隆升速率和下切速率等方面均大于青藏高原内部,认为青藏高原东缘的边缘山脉是剥蚀隆升和构造隆升两者叠加的产物。 相似文献
126.
The Tungabhadra River is one of the sacred rivers in south India. Industrial and mining operations on its banks generate enormous amounts of effluent that have led to substantial metal and nutrient contamination of the aquatic system. In the present investigation an attempt has been made to assess variation in the physico-chemical characteristics and speciation of zinc in the water and sediment of the Tungabhadra River. Most of the metal ions in the collected samples were in high concentrations compared to the applicable standards. The Individual Contamination Factor (ICF) of Zn was found to be more at Site-B compared to sites A and C. Zinc-bearing particles were characterized by the different morphologies measuring from large colloidal to small particles which were associated with biological structures or may be present in amorphous nature which were observed by Transition electron microscopy (TEM) with X-EDS (Energy dispersive spectrometry). In conclusion, the level of Zn contamination in the Tungabhadra River is increasing at an alarming rate due to industrial activities. 相似文献
127.
Along with meteorological observations, complementary and systematic oceanographic observations of various physical, biological and chemical parameters have been made at Ocean Station P (OSP) (50°N, 145°W) since the early 1950s. These decadal time scale data have contributed to a better understanding of the physical, biological and chemical processes in the surface layer of the northeastern subarctic region of the Pacific Ocean. These data have demonstrated the importance of the North Pacific in the global carbon cycle and, in particular, the role of biological/chemical processes in the net exchange of CO2 across the air–sea interface. Although we do not fully comprehend how climatic variations influence marine communities or marine biogeochemistry, previous studies have provided some basic understanding of the mechanisms controlling the seasonal and inter-annual variations of biological and chemical parameters (such as phytoplankton, bacteria, nitrate/ammonium concentration) at OSP, and how they affect the carbon cycling in the subarctic North Pacific. In this study, we investigate how these mechanisms might alter the seasonal variations of these parameters at OSP under a 2XCO2 condition. We examine these influences using a new biological model calibrated by the climatological data from OSP. For the 2XCO2 simulation, the biological model is driven off line (i.e., no feedback to the ocean/atmospheric model components) by the climatology plus 2XCO2−1XCO2 outputs from a global surface ocean model and the Canadian GCM. Under the 2XCO2 condition, the upper layer ocean shows an increase in the entrainment rate at the bottom of the mixed layer for OSP during the late autumn and winter seasons, resulting in an increase in the f-ratio. Although there is an overall increase in the primary production (PP) by 3–18%, a decrease in the biomass of small phytoplankton and microzooplankton (due to mesozooplankton grazing) lowers the concentration of dissolved organic matter (DOM) by 4–25%. The model also predicts a significant increase in the concentrations of nitrate and ammonium, and in bacterial production during July and August. Doubling of the atmospheric CO2 from 330 to 660 ppm forces the marine pCO2 to increase by about 63%, much of which is driven by an increased flux of CO2 from the atmosphere to the oceans. 相似文献
128.
《Marine Policy》2017
Iceland's nationwide privatized Individual Transferable Quota (ITQ) system is over thirty years old but remains a topic of public and political debate, particularly because of the continued effects on small-scale fisheries. A national survey of small-boat fishermen was distributed to: (1) identify major defining characteristics of participants in ITQ and non-ITQ fisheries, (2) document and examine differences in satisfaction with fisheries management, and (3) evaluate the existing options for newcomers to participate in small-boat fisheries. Survey results indicate that Icelandic small-boat fishermen are engaged in multiple management systems within a wide range of boat sizes. Those who held quota were more satisfied with the current ITQ system compared to those who did not hold quota; however, nearly all fishermen were still critical of fisheries management in Iceland and the two major non-ITQ options of lumpfish and coastal fishing were not perceived to offer significant opportunity for entry-level fishermen. Dissatisfaction stemmed from the lack of decision-making power, a distrust of scientific advice, and the perception that the ITQ system did not serve the purpose of protecting fisheries resources, but was rather oriented only toward economic goals. The dynamic nature of Icelandic small-boat fishing livelihoods and the pervasive negative attitudes thirty years after ITQ implementation demonstrate the need for culturally appropriate and equitable fisheries management schemes where success is measured in social as well as economic and biological terms. 相似文献
129.
朱静 《云南地理环境研究》1995,7(1):48-57
本文划分出澜沧江中下游斜坡结构类型并分析了各斜坡类型的基本特征、变形机制和演化方式,阐述了斜坡变形破坏对该地区人类经济活动的影响,为评价预测澜沧江中下游斜坡稳定性奠定了基础。 相似文献
130.