63 research outputs found
Spillways Scheduling for Flood Control of Three Gorges Reservoir Using Mixed Integer Linear Programming Model
This study proposes a mixed integer linear programming (MILP) model to optimize the spillways scheduling for reservoir flood control. Unlike the conventional reservoir operation model, the proposed MILP model specifies the spillways status (including the number of spillways to be open and the degree of the spillway opened) instead of reservoir release, since the release is actually controlled by using the spillway. The piecewise linear approximation is used to formulate the relationship between the reservoir storage and water release for a spillway, which should be open/closed with a status depicted by a binary variable. The control order and symmetry rules of spillways are described and incorporated into the constraints for meeting the practical demand. Thus, a MILP model is set up to minimize the maximum reservoir storage. The General Algebraic Modeling System (GAMS) and IBM ILOG CPLEX Optimization Studio (CPLEX) software are used to find the optimal solution for the proposed MILP model. The China’s Three Gorges Reservoir, whose spillways are of five types with the total number of 80, is selected as the case study. It is shown that the proposed model decreases the flood risk compared with the conventional operation and makes the operation more practical by specifying the spillways status directly
DeepSolo: Let Transformer Decoder with Explicit Points Solo for Text Spotting
End-to-end text spotting aims to integrate scene text detection and
recognition into a unified framework. Dealing with the relationship between the
two sub-tasks plays a pivotal role in designing effective spotters. Although
transformer-based methods eliminate the heuristic post-processing, they still
suffer from the synergy issue between the sub-tasks and low training
efficiency. In this paper, we present DeepSolo, a simple detection transformer
baseline that lets a single Decoder with Explicit Points Solo for text
detection and recognition simultaneously. Technically, for each text instance,
we represent the character sequence as ordered points and model them with
learnable explicit point queries. After passing a single decoder, the point
queries have encoded requisite text semantics and locations and thus can be
further decoded to the center line, boundary, script, and confidence of text
via very simple prediction heads in parallel, solving the sub-tasks in text
spotting in a unified framework. Besides, we also introduce a text-matching
criterion to deliver more accurate supervisory signals, thus enabling more
efficient training. Quantitative experiments on public benchmarks demonstrate
that DeepSolo outperforms previous state-of-the-art methods and achieves better
training efficiency. In addition, DeepSolo is also compatible with line
annotations, which require much less annotation cost than polygons. The code
will be released.Comment: The code will be available at
https://github.com/ViTAE-Transformer/DeepSol
Cosmic Radio Background from Primordial Black Holes at Cosmic Dawn
The presence of an extra radio background besides the cosmic microwave
background has important implications for the observation of the 21-cm signal
during the cosmic Dark Ages, Cosmic Dawn, and epoch of Reionization. The strong
absorption trough found in the 21-cm global spectrum measured by the EDGES
experiment, which has a much greater depth than the standard model prediction,
has drawn great interest to this scenario, but more generally it is still of
great interest to consider such a cosmic radio background (CRB) in the early
Universe. To be effective in affecting the 21-cm signal at early time, such a
radio background must be produced by sources which can emit strong radio
signals but modest amount of X-rays, so that the gas is not heated up too
early. We investigate the scenario that such a radio background is produced by
the primordial black holes (PBHs). For PBH with a single mass, we find that if
the PBHs' abundance (ratio of total PBH mass density to
total matter density) and mass satisfy the relation for , and have jet emission, they can generate
a CRB required for reproducing the 21-cm absorption signal seen by the EDGES.
The accretion rate can be boosted if the PBHs are surrounded by dark matter
halos, which permits lower value to satisfy the EDGES
observation. In the latter scenario, since the accretion rate can evolve
rapidly during the Cosmic Dawn, the frequency (redshift) and depth of the
absorption trough can determine the mass and abundance of the PBHs
simultaneously. For absorption trough redshift 17 and depth
mK, it corresponds to and .Comment: 16 pages, 13 figures, accepted for publication in PR
A New Guide Lifter for the Transceiver of USBL
A new guide lifter has been put forward for the transceiver of Ultra Short Base Line (USBL) with a worm gear reducer applied as self-locking of the lifter and a chain structure applied to drive the sliding shaft moving up and down. The new device is 7500 mm long and connected to the end of the transceiver. Linear motion products are introduced to ensure the shaft unable to rotate and the position measurements are provided by position sensors. A heavy self-sealing sliding bearing, which is 800 mm in length, keeps the shaft running reliably. Then the three-dimensional model is built and the structure parameters of the lifter are calculated. Later, the working process of the lifter is simulated to guarantee the movement parameters meet the request of USBL. Finally, the experiment on the intensity and stiffness of the lifter is carried out via the finite element model of the lifter built in ANSYS with the maximum load conditions and the result has been experimentally verified. This device provides a reliable approach of operating USBL which plays a vitally important role in ocean exploration and the research results are successfully applied to the scientific research vessels of Dayang No. 1 as well as Xiangyanghong No. 9
Roles of sex hormones in mediating the causal effect of vitamin D on osteoporosis: A two-step Mendelian randomization study
BackgroundAlthough 25-hydroxyvitamin D [25(OH)D] is a risk factor for osteoporosis, it is not clear whether sex hormones mediate this casual association. We aimed to explore how sex hormones affect the association between 25(OH)D and osteoporosis to provide meaningful insights on the underlying mechanisms from a genetic perspective.MethodsGenetic variations in 25(OH)D, total testosterone (TT), androstenedione (A4), estradiol (E2), and testosterone/17β-estradiol (T/E2) were determined through summary statistics. Taking osteoporosis as the outcome (FinnGen biobank, 332,020 samples), we conducted a Mendelian randomization (MR) analysis to establish the association between 25(OH)D and these sex hormones. The two-step MR analysis quantified the mediatory effects of sex hormones on osteoporosis. The results were further verified by pleiotropy and heterogeneity analyses.ResultsMR results showed that 25(OH)D (OR= 1.27, p = 0.04) and TT (OR= 1.25, p = 0.04) had a causal effect on osteoporosis. No significant associations were observed between the other sex hormones (A4, E2, and T/E2) and osteoporosis (p>0.05). Sensitivity analysis (p>0.05) confirmed the robustness of the MR results. The two-step MR analysis provided evidence that the mediatory effect of TT was 0.014 (the percentage of TT mediation was 5.91%). Moreover, the direct effect of 25(OH)D on osteoporosis was 0.221. A4, E2, and T/E2 were not considered as potential mediators of the role of 25(OH)D as a risk factor for OP.ConclusionThis study, through MR analysis, showed that TT mediates the causal effect of 25(OH)D on osteoporosis. Interventions targeting TT, therefore, have the potential to substantially reduce the burden of osteoporosis attributable to high 25(OH)D
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