487 research outputs found
Experimental Study on the Mechanisms of Soil Water-Solute- Heat Transport and Nutrient Loss Control
The release and migration of nutrients, pesticides, and other chemicals in the runoff from agricultural lands is not only an economic loss but a threat to the quality of our surface and groundwater. In contrast to pollution from point sources, pollution from non-point sources is often low in intensity but high in volume. The development of a physically based model to simulate the transport of soil solutes would provide a better understanding of transport mechanisms and assist in the development of effective methods to control the loss of nutrients from soils and the pollution of waterways. As a result, numerous studies have been conducted in this area. But due to the soil genesis and human activity, the process is very complex, which can have a great impact on soil water movement, solute transport, as well as nutrient loss. In this study, we determined water movement and solute and heat transport through columns of disturbed soil samples. We also carried out simulated rainfall experiments on an artificial slope to study the nutrient loss
Investigation and protection of fishery resources in the middle of Bohai Sea
In May and October 2017, 12 stations were set up in the Central Bohai Sea for fishery resources investigation. The results show that there are many dominant species in this area, and the inshore fishery resources are higher than those in the open sea because of the abundant nutrients from land, the high density of zooplankton and the food of swimming animals. In order to effectively protect the fishery resources in the Central Bohai Sea, this paper puts forward some suggestions, such as strengthening the protection propaganda, scientific and reasonable fishing, and strengthening the management of marine environment
GEOMETRIC ANALYSIS TOOLS FOR MESH SEGMENTATION
Surface segmentation, a process which divides a surface into parts, is the basis for many surface manipulation applications which include model metamorphosis, model simplifica- tion, model retrieval, model alignment and texture mapping. This dissertation discusses novel methods for geometric surface analysis and segmentation and applications for these methods. Novel work within this dissertation includes a new 3D mesh segmentation algo- rithm which is referred to as the ridge-walking algorithm. The main benefit of this algo- rithm is that it can dynamically change the criteria it uses to identify surface parts which allows the algorithm to be adjusted to suit different types of surfaces and different segmen- tation goals. The dynamic segmentation behavior allows users to extract three different types of surface regions: (1) regions delineated by convex ridges, (2) regions delineated by concave valleys, and (3) regions delineated by both concave and convex curves. The ridge walking algorithm is quantitatively evaluated by comparing it with competing algo- rithms and human-generated segmentations. The evaluation is accompanied with a detailed geometrical analysis of a select subset of segmentation results to facilitate a better under- standing of the strengths and weaknesses of this algorithm.
The ridge walking algorithm is applied to three domain-specific segmentation prob- lems. The first application uses this algorithm to partition bone fragment surfaces into three semantic parts: (1) the fracture surface, (2) the periosteal surface and (3) the articular surface. Segmentation of bone fragments is an important computational step necessary in developing quantitative methods for bone fracture analysis and for creating computational tools for virtual fracture reconstruction. The second application modifies the 3D ridge walking algorithm so that it can be applied to 2D images. In this case, the 2D image is modeled as a Monge patch and principal curvatures of the intensity surface are computed iv for each image pixel. These principal curvatures are then used by ridge walking algorithm
to segment the image into meaningful parts. The third application uses the ridge walking algorithm to facilitate analysis of virtual 3D terrain models. Specifically, the algorithm is integrated as a part of a larger software system designed to enable users to browse, visualize and analyze 3D geometric data generated by NASA’s Mars Exploratory Rovers Spirit and Opportunity. In this context, the ridge walking algorithm is used to identify surface features such as rocks in the terrain models
rac-3,9-Bis(3-chloroÂphenÂyl)-2,4,8,10-tetraÂoxaspiroÂ[5.5]undecaÂne
In the title compound, C19H18Cl2O4, the two non-planar six-membered heterocycles passing through the spiro-C atom both adopt chair conformations, and the dihedral angle between the two benzene rings is 7.2 (1)°. In the crystal, the enantiÂomers with R and S configurations are generated by the symmetry elements of the centrosymmetric space group, forming a racemic crystal. InterÂmolecular C—H⋯π and weak C—H⋯O interÂactions link the molÂecules in the crystal structure
The contribution of circadian clock to the biological processes
All organisms have various circadian, behavioral, and physiological 24-h periodic rhythms, which are controlled by the circadian clock. The circadian clock controls various behavioral and physiological rhythms. In mammals, the primary circadian clock is present in the suprachiasmatic nucleus of the hypothalamus. The rhythm of the circadian clock is controlled by the interaction between negative and positive feedback loops, consisting of crucial clock regulators (including Bmal1 and Clock), three cycles (mPer1, mPer2, and mPer3), and two cryptochromes (Cry1 and Cry2). The development of early mammalian embryos is an ordered and complex biological process that includes stages from fertilized eggs to blastocysts and undergoes important morphological changes, such as blastocyst formation, cell multiplication, and compaction. The circadian clock affects the onset and timing of embryonic development. The circadian clock affects many biological processes, including eating time, immune function, sleep, energy metabolism, and endocrinology, therefore, it is also crucial for overall health, growth and development after birth. This review summarized the effects of the circadian clock in the body’s physiological activities. A new strategy is proposed for the prevention of malformations or diseases by regulating the circadian clock or changing circadian rhythms
Gait Recognition in the Wild: A Large-scale Benchmark and NAS-based Baseline
Gait benchmarks empower the research community to train and evaluate
high-performance gait recognition systems. Even though growing efforts have
been devoted to cross-view recognition, academia is restricted by current
existing databases captured in the controlled environment. In this paper, we
contribute a new benchmark and strong baseline for Gait REcognition in the Wild
(GREW). The GREW dataset is constructed from natural videos, which contain
hundreds of cameras and thousands of hours of streams in open systems. With
tremendous manual annotations, the GREW consists of 26K identities and 128K
sequences with rich attributes for unconstrained gait recognition. Moreover, we
add a distractor set of over 233K sequences, making it more suitable for
real-world applications. Compared with prevailing predefined cross-view
datasets, the GREW has diverse and practical view variations, as well as more
naturally challenging factors. To the best of our knowledge, this is the first
large-scale dataset for gait recognition in the wild. Equipped with this
benchmark, we dissect the unconstrained gait recognition problem, where
representative appearance-based and model-based methods are explored. The
proposed GREW benchmark proves to be essential for both training and evaluating
gait recognizers in unconstrained scenarios. In addition, we propose the Single
Path One-Shot neural architecture search with uniform sampling for Gait
recognition, named SPOSGait, which is the first NAS-based gait recognition
model. In experiments, SPOSGait achieves state-of-the-art performance on the
CASIA-B, OU-MVLP, Gait3D, and GREW benchmarks, outperforming existing
approaches by a large margin. The code will be released at
https://github.com/XiandaGuo/SPOSGait.Comment: Extension of our ICCV 2021 wor
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