Supervised framework for COVID-19 classification and lesion localization from chest CT

Abstract Background: Quick and precise identification of people suspected of having COVID-19 plays a key function in imposing quarantine at the right time and providing medical treatment, and results not only in societal benefits but also helps in the development of an improved health system. Building a deep-learning framework for automated identification of COVID-19 using chest computed tomography (CT) is beneficial in tackling the epidemic. Aim: To outline a novel deep-learning model created using 3D CT volumes for COVID-19 classification and localization of swellings. Methods: In all cases, subjects’ chest areas were segmented by means of a pre-trained U-Net; the segmented 3D chest areas were submitted as inputs to a 3D deep neural network to forecast the likelihood of infection with COVID-19; the swellings were restricted by joining the initiation areas within the classification system and the unsupervised linked elements. A total of 499 3D CT scans were utilized for training worldwide and 131 3D CTscans were utilized for verification. Results: The algorithm took only 1.93 seconds to process the CT amount of a single affected person using a special graphics processing unit (GPU). Interesting results were obtained in terms of the development of societal challenges and better health policy. Conclusions: The deep-learning model can precisely forecast COVID-19 infectious probabilities and detect swelling areas in chest CT, with no requirement for training swellings. The easy-to-train and high-functioning deep-learning algorithm offers a fast method to classify people affected by COVID-19, which is useful to monitor the SARS-CoV-2 epidemic. [Ethiop. J. Health Dev. 2020; 34(4):235-242] Key words: COVID-19, CT scan, deep learning, neural network, DeCoVNet, RT-PCR, computed tomograph

A Design and Construction of Experimental Teaching Platform on Quality and Competence Training Targeted at Students of Liberal Arts

Aiming at addressing the pervasive problems of university experimental teaching on students of liberal arts in our country, the paper points out the necessity of the construction of experimental teaching platform on qualification and competence education targeted at students of liberal arts. Combining the features of being interdisciplinary, comprehensive and innovative in specialties of tourism management, E-business and Business English, a Blackboard based platform system thus designed and introduced to try to present solutions to the key problems concerning experimental teaching functions and interdisciplinary cooperation etc. Keywords: challenge specialties of liberal arts, interdisciplinary, experimental teaching platfor

Resilience Assessment of Hydrogen Integrated Energy System for Airport Electrification

In recent years, the idea of green aviation and environmental protection has received increasing attention from the aviation industry. Hydrogen energy has an important role in the transition to low-carbon energy systems. To address that, this article conducts the technoeconomic analysis for the hydrogen energy system, photovoltaic energy, battery storage system, electric auxiliary power unit (APU) of aircraft, and electric vehicles (EVs) into the electrified airport energy system. Specifically, the model quantifies aircraft electrical load based on passenger' travel behavior, establishes a corresponding APU load characteristic model, and establishes an EV charging load profile based on the flight schedule and sequencing algorithm. A mixed-integer linear programming optimization method based on life cycle theory was proposed to minimize the total costs of hydrogen-integrated energy systems for airports (HIES). However, the resilience advantages of hydrogen energy concerning power failure are little explored in existing academic research. Thus, a resilience assessment method and improvement measure were proposed for HIES. Case studies have been conducted under different optimal hydrogen energy integration configurations and disaster times with resilience assessment by considering periods when the power supply capacity of the grid is insufficient. The results show the effectiveness of the proposed method.</p

Controllable synthesis of branched ZnO/Si nanowire arrays with hierarchical structure

A rational approach for creating branched ZnO/Si nanowire arrays with hierarchical structure was developed based on a combination of three simple and cost-effective synthesis pathways. The crucial procedure included growth of crystalline Si nanowire arrays as backbones by chemical etching of Si substrates, deposition of ZnO thin film as a seed layer by magnetron sputtering, and fabrication of ZnO nanowire arrays as branches by hydrothermal growth. The successful synthesis of ZnO/Si heterogeneous nanostructures was confirmed by morphologic, structural, and optical characterizations. The roles of key experimental parameters, such as the etchant solution, the substrate direction, and the seed layer on the hierarchical nanostructure formation, were systematically investigated. It was demonstrated that an etchant solution with an appropriate redox potential of the oxidant was crucial for a moderate etching speed to achieve a well-aligned Si nanowire array with solid and round surface. Meanwhile, the presence of gravity gradient was a key issue for the growth of branched ZnO nanowire arrays. The substrate should be placed vertically or facedown in contrast to the solution surface during the hydrothermal growth. Otherwise, only the condensation of the ZnO nanoparticles took place in a form of film on the substrate surface. The seed layer played another important role in the growth of ZnO nanowire arrays, as it provided nucleation sites and determined the growing direction and density of the nanowire arrays for reducing the thermodynamic barrier. The results of this study might provide insight on the synthesis of hierarchical three-dimensional nanostructure materials and offer an approach for the development of complex devices and advanced applications

Counting sums of exceptional units in Zn \mathbb{Z}_n

Let $R$ be a commutative ring with the identity $1_{R}$, and let $R^*$ be the multiplicative group of units in $R$. An element $a\in R^*$ is called an exceptional unit if there exists a $b\in R^*$ such that $a+b = 1_{R}$. We set $R^{**}$ to be the set of all exceptional units in $R$. In this paper, we consider the residue-class ring $\mathbb{Z}_n$. For any positive integers $n, s$, and $c\in\mathbb{Z}_n$, let ${\mathcal N}_{s}(n, c): = \sharp\big\{(x_1, ..., x_s)\in (\mathbb{Z}_n^{**})^s : x_1+...+x_s\equiv c \pmod n\big\}$. In 2016, Sander (J.Number Theory 159 (2016)) got a formula for ${\mathcal N}_{2}(n, c)$. Later on, Yang and Zhao (Monatsh. Math. 182 (2017)) extended Sander's theorem to finite terms by using exponential sum theory. In this paper, using matrix theory, we present an explicit formula for ${\mathcal N}_{s}(n, c)$. This extends and improves earlier results

The Number of Rational Points of a Family of Algebraic Varieties over Finite Fields

Let 𝔽q stand for the finite field of odd characteristic p with q elements (q = pn, n ∈ ℕ) and [Formula: see text] denote the set of all the nonzero elements of 𝔽q. Let m and t be positive integers. By using the Smith normal form of the exponent matrix, we obtain a formula for the number of rational points on the variety defined by the following system of equations over [Formula: see text] where the integers t &gt; 0, r0 = 0 &lt; r1 &lt; r2 &lt; ⋯ &lt; rt, 1 ≤ n1 &lt; n2 &lt;, ⋯ &lt; nt and 0 ≤ j ≤ t − 1, bk ∊ 𝔽q, ak,i ∊ [Formula: see text] (k = 1, …, m, i = 1, …, rt), and the exponent of each variable is a positive integer. Further, under some natural conditions, we arrive at an explicit formula for the number of 𝔽q-rational points on the above variety. It extends the results obtained previously by Wolfmann, Sun, Wang, Hong et al. Our result gives a partial answer to an open problem raised in [The number of rational points of a family of hypersurfaces over finite fields, J. Number Theory 156 (2015) 135–153]. </jats:p