Studies of the chemical characteristics of mussels and clams in seafloor hydrothermal fields are important for understanding mass fluxes and elemental partitioning from hydrothermal vents into the biosphere, metal bio...
详细信息
Studies of the chemical characteristics of mussels and clams in seafloor hydrothermal fields are important for understanding mass fluxes and elemental partitioning from hydrothermal vents into the biosphere, metal bioaccumulation of seafloor hydrothermal ecosystems, and the sources and sinks of biogeochemical and fluid cycles. We are the first to measure the mineral, major, trace and rare earth element, and carbon and oxygen isotope compositions of mussels (Bathymodiolus platifrons) and clams (Conchocele bisecta) from the Tangyin and Yonaguni Knoll IV hydrothermal fields in the southwestern Okinawa Trough. Mineralogical analysis shows that the carbonate shells of the mussel and clam samples are mainly composed of calcite and aragonite. Metal elements exhibit linear correlations in the shells (e.g., V and U) and tissues (e.g., li and Rb) of the mussels and clams, suggesting that not all positive correlations of elements in tissues are inherited by the shells. V/As, Ca/Sr, and Fe/Cr ratios in the mussels and clams are close to those in the seawater, indicating that element ratios of seawater might be inherited by the mussels and clams. In addition, the Fe/Cr ratio of the shells of both mussels and clams can be used to trace the local seawater composition. The total LREE concentrations of mussel and clam tissue samples are higher than those of the mussel and clam shell samples, are similar to the hydrothermal fluids, exhibit LREE enrichment (La-CN/Nd-CN ratios = 1.86-32.1), and no or only slightly negative Eu anomalies, indicating that benthic animals are a sink of LREEs from hydrothermal fluids, and that the Eu/Eu* ratios of fluids change when fluids are incorporated into the tissues of the mussels and clams. In addition, the delta C-13 values of mussel shell samples are heavier than those of the clam shell samples in the hydrothermal field, indicating that more than one carbon source may be involved in defining the delta C-13 compositions of the shells. The majority
A novel Povarov-type reaction for straightforward synthesis of novel spiro bi-tetrahydroquinolines with readily available 1,2-DHQs (1,2-dihydroquinolines) and aromatic imines was developed. The reaction could be selec...
详细信息
A novel Povarov-type reaction for straightforward synthesis of novel spiro bi-tetrahydroquinolines with readily available 1,2-DHQs (1,2-dihydroquinolines) and aromatic imines was developed. The reaction could be selectively stopped at the first stage under a Bronsted acid catalyst to afford the corresponding functionalized 1,2-DHQs conveniently.
In recent years, unmanned autonomous vehicle navigation technology or UAV research is a hot topic in the field of machine vision, and obstacle detection is the basis of autonomous navigation. In this thesis, the autho...
详细信息
ISBN:
(纸本)9781479953905
In recent years, unmanned autonomous vehicle navigation technology or UAV research is a hot topic in the field of machine vision, and obstacle detection is the basis of autonomous navigation. In this thesis, the author analyzed the deficiency of stereoscopic vision and classified current monocular obstacle detection algorithms. According to the properties of algorithms, this paper elaborated the function of algorithms based on features, focal length and movements respectively. The author also discussed current situation and prospects for various types of algorithms, including feature extraction and matching, focusing and defocusing model, background subtraction, frame difference and optical flow. Finally, this paper summarized advantages and disadvantages of different autonomous navigation algorithm and discussed the prospect of the monocular obstacle detection technology.
The algorithm presented here is used on unmanned aerial vehicles system. In 2013,*** proposed a matching cost computation model(or function), This matching cost model combined three kinds of constraints, the cost func...
详细信息
ISBN:
(纸本)9781479953905
The algorithm presented here is used on unmanned aerial vehicles system. In 2013,*** proposed a matching cost computation model(or function), This matching cost model combined three kinds of constraints, the cost function is formulated by combining three individual costs: a cost computed on an extended census transformation of the images;the absolute difference cost, taking into account information from colour channels;and a cost based on the principal image derivatives. Experiments show that the cost function is excellent performance in similar estimates. Apply it to the stereo matching of ancient buildings, it is favorable for practical. However, this experiment, in color mutated region, leaded to blurred border. Therefore, our proposed method added color space structural information, which based on HVS Weber's law, to the cost function. we use the differential excitation of WLD reflects the structure of color space. This robust cost measures can reduce percent of bad pixels in mutated color region. The proposed method use color image, which is used after epipolar line rectification.
暂无评论