Objective To discern the symptomatic features of coronavirus disease 2019 (COVID‐19) and to evaluate the severity and prognosis of the disease. Methods In this retrospective cohort study, 932 hospitalized patients with COVID‐19 in Wuhan were enrolled, including 52 severe and 880 non‐severe cases. All patients were followed up for 3 months after discharge. The symptomatic features and follow‐up data of the patients in both groups were analyzed and compared. Results Of the 932 patients, fever (60.0%), cough (50.8%) and fatigue (36.4%) were the most common symptoms. In total, 32.7% of the severe cases presented with gastrointestinal symptoms at disease onset, including anorexia, nausea, vomiting or diarrhea, which was significantly higher than that of the non‐severe group (P = 0.0015). The incidence of olfactory disturbance and dysgeusia was only 3.1% and 6.2%, respectively. After adjusting for age and sex, multivariate regression analysis showed that fever lasting for over 5 days (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.00‐3.62, P = 0.0498), anorexia at onset (OR 2.61, 95% CI 1.26‐5.40, P = 0.0096), and modified Medical Research Council level above grade 2 when dyspnea occurred (OR 14.19, 95% CI 7.01‐28.71, P < 0.0001) were symptomatic risk factors for severe COVID‐19. During the follow‐up, cough (6.2%), dyspnea (7.2%), fatigue (1.8%), olfactory disturbance and dysgeusia (1.5%) were the significant remaining symptoms. Conclusions COVID‐19 causes clusters of symptoms with multiple systems involved. Certain symptomatic characteristics have predictive value for severe COVID‐19. Short‐term follow‐up data reveal that most patients have a good prognosis.

As one of the most promising research directions, cooperative location with high precision and low-cost IMU is becoming an emerging research topic in many positioning fields. Low-cost MEMS/DVL is a preferred solution for dead-reckoning in multi-USV cooperative network. However, large misalignment angles and large gyro drift coexist in low-cost MEMS that leads to the poor observability. Based on cubature Kalman filter (CKF) algorithm that has access to high accuracy and relative small computation, dual-model filtering scheme is proposed. It divides the whole process into two subsections that cut off the coupling relations and improve the observability of MEMS errors: it first estimates large misalignment angle and then estimates the gyro drift. Furthermore, to improve the convergence speed of large misalignment angle estimated in the first subsection, “time reversion” concept is introduced. It uses a short period time to forward and backward several times to improve convergence speed effectively. Finally, simulation analysis and experimental verification is conducted. Simulation and experimental results show that the algorithm can effectively improve the cooperative navigation performance.

Taking the deep foundation pit engineering of a Subway Station as background. The paper introduces the projects surroundings,geological and hydrological conditions of the proposed field and the retaining structural type. According to the engineering characteristics,the project was divided into four typical operating conditions,the deformation rules of deep foundation pit at subway station in tunneling are studied with the method of FLAC3D numerical simulation,the supporting structures choose by the bored piles and interior support. The analysis of the horizontal deformation of the retaining structures, the settlement law and the influence sphere of surrounding soil. The conclusion in this paper can provides reference for the reasonable design and safety construction of deep foundation pit.

A design idea of power supply for aircraft battery charger is proposed, which is based on the thought of aircraft batteries characters such as small capacity and same working voltage range. The crucial parameters of the power supply are set depended on analyzing the capacity and voltage range of aircraft batteries. After analyzing the features of power converters, the ZVS phase shifted full-bridge soft-switching circuit is chose and then crucial components are designed. The experiment results show that the design scheme of the power supply can meet using-requirements. The design scheme of general-purpose power supply solve the problem that aircraft battery charger has bad general-using ability.

UV radiation, as an effective method for bacteria inactivation, has been applied popularly on ballast water treatment. However, the inactivation efficiencies of UV radiation greatly depend on the UV intensity which distributed unevenly in water and can be deeply affected by the suspending particles in water. For better understanding of the spatial distribution of UV radiation, a 16W UVC lamp was measured underwater to detect the radiant intensity over horizontal and vertical distance. The distribution tendency of UV radiant intensity was probed behind large amounts of experimental data. In addition, four types of different water including tap water, clean seawater, seawater mixed with suspending substances (SS), and seawater mixed with typical algae, were studied to identity the influence of water environment on UV transmission. The impacting significances were compared among different water quality, to optimize the ballast water treatment methods combining with UV radiation.