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61.
通过对2 131km高分辨率浅地层剖面资料分析和研究,揭示了威海市近海海域浅地层结构特征,分析了海洋灾害地质因素类型及分布特征,并绘制了主要灾害地质因素分布图。威海市近海海域65m以浅地层共分为5层,第一层为全新世泥质楔形体,地层厚度8~15m;第二层为末次盛冰期以来的海侵层,厚度一般小于3m;第三层为MIS2期的陆相沉积层,地层厚度3~8m;第四层为MIS3期的海相沉积层,厚度3~6m;第五层未完全揭示。近海海域灾害地质因素主要包括埋藏下切谷、浅部断层、浅层气、海底沙波沙脊、浅埋起伏基岩等5种类型;埋藏下切谷主要分布在南部海域U3地层单元中;浅部断层主要分布在南部海域水深大于20m的海底堆积平原;浅层气主要分布在北部海域,东部和南部海域面积较小;海底沙波沙脊主要分布在荣成成山头外海海域;浅埋起伏基岩主要分布在基岩海岸和岛屿较近的海域。  相似文献   
62.
High-biomass red tides occur frequently in some semi-enclosed bays of Hong Kong where ambient nutrients are not high enough to support such a high phytoplankton biomass. These high-biomass red tides release massive inorganic nutrients into local waters during their collapse. We hypothesized that the massive inorganic nutrients released from the collapse of red tides would fuel growth of other phytoplankton species. This could influence phytoplankton species composition. We tested the hypothesis using a red tide event caused by Mesodinium rubrum (M. rubrum) in a semi-enclosed bay, Port Shelter. The red tide patch had a cell density as high as 5.0×105 cells L?1, and high chlorophyll a (63.71 μg L?1). Ambient inorganic nutrients (nitrate: \(\rm{NO}_3^-\), ammonium: \(\rm{NH}_4^+\), phosphate: \(\rm{PO}_4^{3-}\), silicate: \(\rm{SiO}_4^{3-}\)) were low both in the red tide patch and the non-red-tide patch (clear waters outside the red tide patch). Nutrient addition experiments were conducted by adding all the inorganic nutrients to water samples from the two patches followed by incubation for 9 days. The results showed that the addition of inorganic nutrients did not sustain high M. rubrum cell density, which collapsed after day 1, and did not drive M. rubrum in the non-red-tide patch sample to the same high-cell density in the red tide patch sample. This confirmed that nutrients were not the driving factor for the formation of this red tide event, or for its collapse. The death of M. rubrum after day 1 released high concentrations of \(\rm{NO}_3^-\), \(\rm{PO}_4^{3-}\), \(\rm{SiO}_4^{3-}\), \(\rm{NH}_4^+\), and urea. Bacterial abundance and heterotrophic activity increased, reaching the highest on day 3 or 4, and decreased as cell density of M. rubrum declined. The released nutrients stimulated growth of diatoms, such as Chaetoceros affinis var. circinalis, Thalassiothrix frauenfeldii, and Nitzschia sp., particularly with additions of \(\rm{SiO}_4^{3-}\) treatments, and other species. These results demonstrated that initiation of M. rubrum red tides in the bay was not directly driven by nutrients. However, the massive inorganic nutrients released from the collapse of the red tide could induce a second bloom in low-ambient nutrient water, influencing phytoplankton species composition.  相似文献   
63.
The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-dish aperture telescope with a cable-driven parallel robot introduced to achieve the highest sensitivity in the world.However,to realize the high-precision,mechanical equations of such a robot are always complicated,so that it is difficult to achieve real-time control by the traditional iterative method.In this regard,this paper proposes an approximately analytical solution method,which uses the approximately linear relationship between the main parameters of FAST to bypass some iterations.With the coefficients of the relationship extracted,static or quasi-static mechanical equations can be analytically solved.In this paper’s example,this method saves at least 90%of the calculating time and the calculated values are consistent with the experimental data.With such huge efficiency improvements,real-time and high-precision control of the FAST will no longer be difficult work.Besides,all the work in this paper is expected to be used in the FAST.  相似文献   
64.
基于金乡县南部地区土地质量地球化学调查与评价项目,系统采集表层土壤和大蒜样品,对As、Cd、Cr、Cu、Hg、Ni、Pb、Zn共8种重金属元素全量及形态数据进行深入分析,研究发现,土壤重金属形态除Cd、Hg外以残渣态占绝对优势;重金属生物可利用系数与SOM、pH、CEC均呈负相关;大蒜植株不同部位对元素的富集特征具有明显差异性,As、Cd、Cr、Pb、Ni、Cu、Zn表现为须根>叶身>假茎>蒜头;蒜头Cd与土壤Cd全量呈显著性正相关,其余元素与对应土壤中全量相关关系不明显。  相似文献   
65.
Under the two initial 1‐D one parameter velocity distribution forms (one is normal, the other is exponential), the z direction scale height evolution of normal neutron stars in the Galaxy is studied by numerical simulation. We do statistics for the cases at different time segments, also do statistics for the cumulative cases made of each time segment. The results show in the cumulative cases the evolution curves of the scale heights are smoother than in the each time segment, i.e., the cumulation improve the signal‐to‐noise ratio. Certainly the evolution cases are different at different Galactic disk locations, which also have very large difference from the average cases in the whole disk. In the initial stages of z evolution of normal neutron stars, after the beginning transient states, the cumulative scale heights increase linearly with time, and the cumulative scale height increasing rates have linear relationship with the initial velocity distribution parameters, which have larger fluctuation in the vicinity of the Sun than in the whole disk. We utilize the linear relationship of the cumulative scale height increasing rates vs. the initial velocity distribution parameters in the vicinity of the Sun to make comparison with the observation near the Sun. The results show if there is no magnetic decay, then the deserved initial velocity parameters are obvious lower than the present well known results from some authors; whereas if introducing magnetic decay, for the 1‐D normal case we can make consistence among concerning results using magnetic decay time values which are supported by some authors, while for the 1‐D exponential case the results show the lackness of young pulsar samples in the larger z in the vicinity of the Sun (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
66.
冀北赤城红旗营子群中变质橄榄岩呈透镜状或团块状产于黑云斜长片麻岩之中,通过对其进行详细的岩石学和地球化学研究.结果显示:岩石类型为强烈蛇纹石化的方辉橄榄岩,具粒状变晶结构或鬣刺结构,变质橄榄岩富ω(MgO)(37.49%~38.91%),贫ω(CaO)(0.12%~1.17%),ω(Al2O3)(0.54%~1.54%)和ω(FeO*)(5.51%~9.06%),ω(TiO2)介于0.01%~0.04%之间,REE含量低于原始地幔,过渡金属元素表现为不对称的W型配分型式,在Ti和Cu处形成明显的负异常谷.上述特征表明变质橄榄岩相当于SSZ型地幔橄榄岩,可能来自于消减带之下的上地幔,属于部分熔融程度很高的亏损地幔岩,因构造侵位而分布于红旗营子群之中,部分岩块则经历了俯冲-消减作用而形成鬣刺结构.  相似文献   
67.
1INTRODUCTIONSoil is the basis of human's living. Soil moisture plays asignificant role in studying the matter and energy ex-changes in global hydrology sphere. The evaporation ofsoil moisture has an influence on the water vapor cycle.Meanwhile soil moisture is also one of the firsthandmeasurable parameters in crop yield estimation and wa-ter resources management (JACKSON et al., 1993). Theinfluence of the interaction of land and atmosphere onsoil moisture can bring about anomalous cli…  相似文献   
68.
北京市GPS网解算时IGS站的选取实验   总被引:5,自引:3,他引:5  
用实验的方法,讨论了北京市GPS台网在用GAMIT软件解算时,选取IGS基准站的空间分布(南北半球、网内网缘、均匀展布)、数量分布(0到8个IGS站)对解算结果精度的影响。由于受观测站数量和IGS站观测数据质量的影响,在保证精度的前提下,为了提高观测数据的利用率,需要增加IGS站数量。根据2004全年的解算结果,北京台网选择9到10个IGS站较为合适。  相似文献   
69.
We report new Zr isotope evidence for live (92)Nb (mean life: tau&d1;92Nb=52 Myr) within the early solar system resulting in &parl0;92Nb&solm0;93Nb&parr0;initial approximately 10-3. The meteoritic minerals rutile and zircon have, respectively, very high and very low Nb/Zr ratios and are ideal for exploring the (92)Nb-(92)Zr chronometer. Rutiles exhibit high positive straightepsilon92Zr ( approximately 14-36) while a zircon has a negative straightepsilon92Zr ( approximately -4), as would be expected if (92)Nb was live in the early solar system. The meteoritic rutiles appear to be young, with apparent times of formation of approximately 80-220 Myr subsequent to the origin of the solar system. The initial (92)Nb/(92)Mo for the solar system is broadly compatible with a model of uniform production if the (92)Nb/(92)Mo production ratio for Type II supernova (SNII) sources with neutrino-driven winds is used. Data for all the now extinct p-process nuclides ((92)Nb, (97)Tc, and (146)Sm) are consistent with these isotopes being derived by uniform production from SNII sources and a free decay interval of approximately 10 Myr. Consideration of a range of models indicates that the average p-process production ratio of (92)Nb/(92)Mo needs to be at least in the range of 0.06-0.25.  相似文献   
70.
推导了冷却物冷藏间内湿空气热物理参数计算方程,并编制了湿空气热物理参数计算程序。该程序能快速、精确地计算冷却物冷藏间内不同气流速度、不同气压的湿气热物理参数  相似文献   
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