Despite the great progress of deep learning and target detection in recent years, the accurate detection of the occluded targets in remote sensing images still remains a challenge. In this letter, we ...propose a new detection method called local attention networks to improve the detection of occluded airplanes. Following the idea of "divide and conquer," the proposed method is designed by first dividing an airplane target into four visual parts: head, left/right wings, body, and tail, and then considering the detection as the prediction of the individual key points in each of the visual parts. We further introduce an additional attention branch in the standard detection pipeline to enhance the features and make the model focus on individual parts of a target even if it is only partially visible in the image. Detection results and ablation studies on three remote sensing target detection data sets (including two publicly available ones) demonstrate the effectiveness of our method, especially for occluded airplane targets. In addition, our method outperforms the other state-of-the-art detection methods on these data sets.
Selenium (Se) is an essential micronutrient that has several important functions in animal and human health. The biological functions of Se are carried out by selenoproteins (encoded by twenty-five ...genes in human and twenty-four in mice), which are reportedly present in all three domains of life. As a component of selenoproteins, Se has structural and enzymatic functions; in the latter context it is best recognized for its catalytic and antioxidant activities. In this review, we highlight the biological functions of Se and selenoproteins followed by an elaborated review of the relationship between Se and female reproductive function. Data pertaining to Se status and female fertility and reproduction are sparse, with most such studies focusing on the role of Se in pregnancy. Only recently has some light been shed on its potential role in ovarian physiology. The exact underlying molecular and biochemical mechanisms through which Se or selenoproteins modulate female reproduction are largely unknown; their role in human pregnancy and related complications is not yet sufficiently understood. Properly powered, randomized, controlled trials (intervention vs. control) in populations of relatively low Se status will be essential to clarify their role. In the meantime, studies elucidating the potential effect of Se supplementation and selenoproteins (i.e., GPX1, SELENOP, and SELENOS) in ovarian function and overall female reproductive efficiency would be of great value.
Abstract
The lateral impact behavior of hybrid fiber-reinforced polymer (FRP)-ultrahigh-performance concrete (UHPC)-steel double-skin tubular columns (DSTCs) was experimentally investigated in this ...study. Seven specimens, which had an outer diameter of 168 mm and a length of 2,000 mm, were tested under lateral impact loading. Different parameters, including the axial force level, impact energy, concrete type, void ratio, FRP tube thickness, and the presence/absence of the FRP tube, were investigated. The dynamic responses, including global/local damage modes, lateral deflection–time histories, impact force–time histories, strain–time histories, and acceleration–time histories, were investigated. The test results prove that the hybrid UHPC DSTCs exhibit very ductile behavior under lateral impact loading. The hybrid UHPC DSTCs have a higher lateral impact resistance capacity as compared to the hybrid DSTCs infilled with normal-strength concrete. The lateral impact resistance capacity of hybrid UHPC DSTCs with an applied axial force of 200 kN can be improved to some extent compared with those without any axial force. The impact energy, the void ratio, the FRP tube thickness, and the presence/absence of the FRP tube can significantly affect the lateral impact behavior of hybrid UHPC DSTCs. Furthermore, the lateral impact behaviors of hybrid DSTCs, concrete-filled double-skin steel tubes (CFDSTs), and concrete-filled steel tubes (CFSTs) were compared and discussed based on the experimental results in this study as well as in other literature studies.
Acidification and pollution are two major threats to agricultural ecosystems; however, microbial community responses to co-existed soil acidification and pollution remain less explored. In this ...study, arable soils of broad pH (4.26-8.43) and polycyclic aromatic hydrocarbon (PAH) gradients (0.18-20.68 mg kg
) were collected from vegetable farmlands. Bacterial community characteristics including abundance, diversity and composition were revealed by quantitative PCR and high-throughput sequencing. The bacterial 16S rRNA gene copies significantly correlated with soil carbon and nitrogen contents, suggesting the control of nutrients accessibility on bacterial abundance. The bacterial diversity was strongly related to soil pH, with higher diversity in neutral samples and lower in acidic samples. Soil pH was also identified by an ordination analysis as important factor shaping bacterial community composition. The relative abundances of some dominant phyla varied along the pH gradient, and the enrichment of a few phylotypes suggested their adaptation to low pH condition. In contrast, at the current pollution level, PAH showed marginal effects on soil bacterial community. Overall, these findings suggest pH was the primary determinant of bacterial community in these arable soils, indicative of a more substantial influence of acidification than PAH pollution on bacteria driven ecological processes.
•Axial compressive behavior of PET FRP/CFRP-confined SSC columns was investigated.•The type and thickness of FRP jackets and the type of mixing water of SSC were the variables of this study.•A ...modified analysis-oriented model with a new dilation equation was proposed for the PET FRP-confined SSC.
Since fiber-reinforced polymer (FRP) composites possess excellent corrosion resistance, they have great potential of use with seawater sea-sand concrete (SSC) for the construction of marine and coastal infrastructure. The existing research on SSC columns confined with FRP jackets, however, is rather limited. Most of the limited research has focused on the axial compressive behavior of SSC columns confined by conventional FRP jackets (made from carbon and glass FRP composites). This paper presents results from the first-ever experimental study on the behavior of axially loaded circular SSC columns confined by polyethylene terephthalate (PET) FRP jackets, which are composed of a new and more promising type of FRP composites with a bilinear stress-strain response and a large rupture strain. Parameters varied between the tests presented in this paper included the type and thickness of FRP jackets and the type of mixing water used for casting the SSC. A modified analysis-oriented model was developed in which a new dilation equation was proposed for the PET FRP-confined SSC. The reliability and accuracy of the analysis-oriented model were then examined by comparisons between the predicted results and the test results of the FRP-confined SSC.
Fiber-reinforced polymer (FRP) composites have been widely used in civil engineering for either strengthening existing deteriorated reinforced concrete (RC) structures or constructing new structures. ...Recently, a new category of FRP composites with a large rupture strain (i.e., referred to as “LRS FRP” in this article) has become increasingly popular. In contrast with conventional FRP composites, LRS FRP composites possess a larger elongation and a lower modulus of elasticity. Since the ultimate state of structures with FRP strengthening generally depends on fracture of the FRP, it is expected that an increase in FRP rupture strain leads to a better performance of structures and LRS FRP composites are particularly suitable for enhancing ductility of structures. This paper presents a state-of-the-art review on the basic characteristics of LRS FRP composites and structural usage of LRS FRP composites (including concrete confined with LRS FRP composites), with further research opportunities associated with LRS FRP composites in structural engineering applications being identified.
In this paper, a quasi-resonant switched-capacitor (QRSC) multilevel inverter (MLI) is proposed with self-voltage balancing for single-phase high-frequency ac (HFAC) microgrids. It is composed of a ...QRSC circuit (QRSCC) in the frontend and an H-bridge circuit in the backend. The input voltage is divided averagely by the series-connected capacitors in QRSCC, and any voltage level can be obtained by increasing the capacitor number. The different operational mechanism and the resulting different application make up for the deficiency of the existing switched-capacitor topologies. The capacitors are connected in parallel partially or wholly when discharging to the load, thus the self-voltage balancing is realized without any high-frequency balancing algorithm. In other words, the proposed QRSC MLI is especially adapted for HFAC fields, where fundamental frequency modulation is preferred when considering the switching frequency and the resulting loss. The quasi-resonance technique is utilized to suppress the current spikes that emerge from the instantaneous parallel connection of the series-connected capacitors and the input source, decreasing the capacitance, increasing their lifetimes, and reducing the electromagnetic interference, simultaneously. The circuit analysis, power loss analysis, and comparisons with typical switched-capacitor topologies are presented. To evaluate the superior performances, a nine-level prototype is designed and implemented in both simulation and experiment, whose results confirm the feasibility of the proposed QRSC MLI.
For wireless communications and the Internet of Things, edge computing has emerged as the potential solution to meet users' demand of fast communications and effective computation by allocating ...computing resources closer to users and tasks, and then reducing the process time and avoiding the transmission of huge amount of data. However, to achieve the potential of edge computing, an effective computation offloading scheme is a key issue needed to be addressed, because it determines how efficient the computing resource allocation and the whole network performance are. Toward providing a solution to such an important issue, this paper formulates the offloading problem as a cooperation game problem about how to share the reasonably adjacent computing resource to users to form an efficient coalition network for the best performance, and then proposes a Shapley value-based computation offloading approach. The proposed approach includes three main steps: Firstly, following the principle of edge computing (users to be close to resources) and reducing the complexity, a clustering algorithm is proposed to divide the whole network into clusters and each cluster has one edge node. Then the non-linear programming is implemented in each cluster and neighboring two or three clusters respectively to obtain the delay values and task allocation results. Finally, to check whether cooperation and coalition among neighboring clusters can bring better network performance, Shapley value is used to evaluate whether combining neighboring clusters in edge computing for the first time. The objective values obtained from the non-linear programming are used to evaluate the profit of different coalitions, which are used to compute Shapley values to determine the final best coalitions between clusters. The numerical results show the effectiveness of the proposed method.
Modeling linguistic information is vital for qualitative decision making (QDM). Compared with single linguistic terms, the complex linguistic expressions (CLEs) are more powerful and flexible to ...express linguistic opinions under uncertainties. Among the existing types of CLEs, the linguistic terms with weakened hedges (LTWHs), which focus on the uncertainty of using single terms, can be used to model the linguistic expressions in natural languages. This paper concentrates on the application of LTWHs in the framework of QDM with preference relations. The concept of linguistic preference relations with hedges is presented after a new computational model of LTWHs is formed. Some consistency concepts, such as weak consistency and additive consistency, are then defined and their properties are studied. Theories and algorithms for consistency checking and improving are proposed. Finally, the availability of the proposed technique is demonstrated by a real application. Different from many studies related to consistency measures, we make use of fuzzy weighted digraphs to develop the theories and algorithms in a visible manner. Moreover, for consistency improving, the degree of consistency is measured by linguistic terms rather than numerical values so that the threshold of satisfactory consistency is interpretable.
The major limitation of the Lagrange programming neural network (LPNN) approach is that the objective function and the constraints should be twice differentiable. Since sparse approximation involves ...nondifferentiable functions, the original LPNN approach is not suitable for recovering sparse signals. This paper proposes a new formulation of the LPNN approach based on the concept of the locally competitive algorithm (LCA). Unlike the classical LCA approach which is able to solve unconstrained optimization problems only, the proposed LPNN approach is able to solve the constrained optimization problems. Two problems in sparse approximation are considered. They are basis pursuit (BP) and constrained BP denoise (CBPDN). We propose two LPNN models, namely, BP-LPNN and CBPDN-LPNN, to solve these two problems. For these two models, we show that the equilibrium points of the models are the optimal solutions of the two problems, and that the optimal solutions of the two problems are the equilibrium points of the two models. Besides, the equilibrium points are stable. Simulations are carried out to verify the effectiveness of these two LPNN models.
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