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High-voltage power supplies are pivotal in sectors such as agriculture, medicine, and environmental protection. However, conventional high-voltage sources are associated with environmental pollution, cumbersome size, high costs, and significant safety risks due to the accompanying high current. To address these challenges, we propose a high-voltage source that employs a direct-current triboelectric nanogenerator (DC-TENG). Based on contact electrification and electrostatic breakdown effects, the inherent electrostatic charges and minimal fixed capacitance enable the DC-TENG to generate ultra-high voltage with low current effortlessly. To fully harness the potential of this high-voltage technology, a theoretical model encompassing multiple discharge domains is developed and the three main constraints on open-circuit voltage are identified. Guided by the model, the optimized DC-TENG achieves a record output voltage of 10.85 kV through structural and material optimizations, effectively achieving water-oil separation and air purification within 2.5 and 3 minutes, respectively. This research not only fully exploits the high-voltage capabilities of DC-TENG but also offers an eco-friendly, portable, cost-effective, and safe alternative for supplying ultra-high voltage. [Display omitted] • A comprehensive model is proposed to reveal the high-voltage characteristics of DC-TENG in theory and practice. • An ultra-high voltage exceeding 10 kV is achieved on a DC-TENG of merely half the size of a finger. • Source voltage, breakdown voltage, and charge leakage are clarified as three main constraints on DC-TENG output voltage. • DC-TENG has wide high-pressure applications, as demonstrated by efficient water-oil separation and air purification. [ABSTRACT FROM AUTHOR]

Acoustic micro-membranes (AMMs) have theoretical advantages in terms of light weight yet high sound transmission loss (STL) at low frequency, but an actual medium- or large-scale specimen usually shows a significant performance degradation. Those lumped-parameter models developed so far lose their accuracy on theoretically describing the actual sound transmission loss of such an assembly. In this paper, the influence of the frame vibration is explored, and an acoustic theory based on a distributed parameter system is established. By coupling the vibration of the frame and the membranes, this theory shows how the acoustic impedance of the assembly depends on the number of membrane cells and the dimensions of the membranes and frame. As the assembly becomes larger, its global response is no longer dominated by the membrane but by the frame, while the latter determines the upper limit of the STL of the whole assembly. Compared to the well-developed lumped-parameter model that works only for small-scale AMMs, this work provides a theoretical foundation for designing larger size yet high loss AMMs, and may pave the way for their use in noise control engineering. [ABSTRACT FROM AUTHOR]

Touch panels utilizing surface-capacitive mechanism are ubiquitous in our daily life. However, the need for an additional probe signal generator and receiver module to detect the resistance distribution and variation caused by finger touching adds complexity and energy consumption to the system. Herein, we propose a self-powered and high-precision tribo-touch-position sensor (TPS) that can operate without an external probe signal generator and receiver module. By detecting the contact electrification signal and extracting the signal ratio between the edges of a uniform resistance film, TPS exhibits precise touch position detection with minimal channels. The mechanism and feasibility of this sensor is systematically analyzed from theory and experiment. Moreover, the resistance range and parameters that affect the sensing performance are discussed in depth. Compared to traditional capacitive touch panels, TPS can function in high moisture conditions and is not limited to grounded objects. Finally, the designed TPS achieves spatial resolutions of 0.001 and 1 mm in touching space and size, and a prototype 2D touch panel is fabricated experimentally. The signals ratio of 2D touch panel changes more obviously in the middle than on the sides while the fingers touch various positions. This work provides an alternative platform for simple and diverse contact localization using triboelectric effect. [Display omitted] • Coupling triboelectrification and uniform resistance film, a touch panel is proposed with self-powered, high-precision and minimum-channel capabilities. • The working mechanism of TPS is established and the resistance range of electrodes (R>10KΩ) for proper TPS function is determined for the first time. • The relationship curve between the signal ratio and relative positions of 2D TTP is investigated and verified for the first time. [ABSTRACT FROM AUTHOR]

With lightweight, high energy conversion and low cost, the triboelectric nanogenerators (TENGs) have presented its tremendous potential as a portable sustainable power source to small-scale portable/wearable electronic device. However, the insufficient output power of TENG is a bottleneck for its practical applications. Here, we report an ultrahigh output power, a whirligig-inspired TENG (Wi-TENG) designed according to an antiqueue whirligig toy that is capable of converting low-frequency pulling motion into a high-frequency rotation. It shows that the rotor in the Wi-TENG achieves a maximum speed of 11,250 rpm. Ultrahigh charge transfer quantity of ~ 310 μC and output power of 40.18 mW are obtained by per pulling of Wi-TENG. Moreover, a maximum short-circuit current of 317 μA and a constant open-circuit voltage peak value of 153 V can be generated by the Wi-TENG, which can rapidly charge a commercial capacitance (100 μF) to ~14 V within 10 s. After power management, this Wi-TENG is successfully demonstrated as a portable sustainable power source for driving a commercial blood glucose meter or a temperature-humidity sensor. This study presents the potential of Wi-TENG as a reliable portable instant power supply for personal health monitoring devices. [ABSTRACT FROM AUTHOR]

Due to their strong transmission loss (TL) at low frequencies, acoustic micro-membranes (AMMs) have been the subject of many studies. In this paper, a theoretical model for AMMs is established which gives a direct insight into their sound insulation qualities. Analysis of the model’s acoustics shows how the sound insulation provided by a membrane can be significantly enhanced, and reveals the intrinsic characteristic of AMMs in mid-low frequency range. Further analysis on two AMMs separated by an air gap gives a quantitative description on how performance varies with the air gap. Using the theoretical model developed here, it is a straightforward matter to adjust an AMM’s parameters to achieve a desired level of attenuation. This work opens the way for the potential application of AMMs in noise control engineering. [ABSTRACT FROM AUTHOR]

Acoustic performance of a micro-perforated panel with an incompletely partitioned cavity (MPPIPC) is investigated. A MPPIPC is achieved by inserting separators, which are shorter than the depth of the cavity, periodically behind the micro-perforated panel (MPP). Due to these separators, the sound field in the cavity is significantly changed. This paper reveals these unique sound reflection modes among the separators, based on which a theoretical model is proposed to calculate the absorption coefficient of a MPPIPC in the diffusion field. Experiments verified the theoretical predictions. These results indicate that the appropriately arranged insertion can improve the performance of a MPP absorber effectively at low frequencies. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) has the output characteristics of high voltage but low current/charge-transfer, making its low efficiency in powering most of electronics. To address this problem, power management circuits consisting of coupled inductors or transformers are usually employed. Here we report an inductor-free, auto-power-management design based on automatic switches between serial-connected and parallel-connected capacitors in a rationally designed manner, so that the output voltage can be lowered and the output charge is enhanced in proportion. In conjunction to theoretical analysis, a TENG along with proof-of-concept power-management units as automatically driven by the triggering motion for TENG is fabricated, which improves the rate for charging a supercapacitor by 5 times. Compared to previous work, this power-management design shows advantages of capability for harvesting low power/frequency scale energy, high scalability, and light weight, which paves a new approach for achieving high-efficient portable TENG-based self-powered system. [ABSTRACT FROM AUTHOR]

Drone delivery is becoming a new trend in the logistics system, but few researches are developed in this field. Locating the target buildings in the drone camera is a crucial technique. However, it is difficult to collect extensive drone-view images and their bounding box annotations for supervised training. Therefore, we address this problem by formulating it as a weakly supervised task and using small amount of category labels as supervision. To extract representative features of cross-view and cross-device images, we propose a Hybrid Convolutional-Transformer (HCT) framework for detection given the very few image-level annotated images. To better evaluate the proposed method in the realistic drone delivery task, we build a drone-view object detection dataset based on the University-1652 benchmark by annotating bounding boxes of target buildings. Extensive experimental results demonstrate the effectiveness of the proposed method. [Display omitted] • A new drone-view detection dataset for evaluation. • A Hybrid Convolutional-Transformer network for drone-view detection. • The proposed method achieves SOTA performance. [ABSTRACT FROM AUTHOR]

Detailed analysis the combined effect of N, O heteroatoms on electrochemical performance through N, O-containing Covalent Triazine-Based Frameworks. Image 1 • A series of p-TIDN is designed using the molecular engineering strategy with the evenly distributed N and O heteroatoms. • The p-TIDN is an ideal template for quantitative study on capacitance properties of heteroatoms and porous structure. • Pyrrolic nitrogen, pyridinic nitrogen, and quinone oxygen are the most conducive species in energy storage. [ABSTRACT FROM AUTHOR]

The exponential increase in the number of genomes deposited in public databases can help us gain a more holistic understanding of the phylogeny and epidemiology of Klebsiella pneumoniae. However, inferring the evolutionary relationships of K. pneumoniae based on big genomic data is challenging for existing methods. In this study, core genes of K. pneumoniae were determined and analysed in terms of differences in GC content, mutation rate, size, and potential functions. We then developed a stable genes-based method for big data analysis and compared it with existing methods. Our new method achieved a higher resolution phylogenetic analysis of K. pneumoniae. Using this genes-based method, we explored global phylogenetic relationships based on a public database of nearly 953 genomes. The results provide useful information to facilitate the phylogenetic and epidemiological analysis of K. pneumoniae , and the findings are relevant for security applications. • The core genome of Klebsiella pneumoniae comprises 3018 genes. • A genes-based method was developed for phylogenetic analysis of big data sets. • Surveillance of CG258 and hyper-virulent lineages facilitated. • The findings are relevant for security applications of K. pneumoniae. [ABSTRACT FROM AUTHOR]

In this paper, we propose a nonlinear finite-time control strategy to solve the motion control problem for a quadrotor with a slung load (QSL). This work aims to realize high-performance motion control for the QSL, even in perturbations. To improve the dynamic performance and the robustness of the QSL system, a novel nonlinear controller is designed with cascade structure. The finite-time stability of the resulting closed-loop system is theoretically analyzed in this work. Furthermore, the advantages of the proposed control strategy are demonstrated by comparison results with different strategies through simulations in MATLAB/SimMechanics. Finally, the effectiveness of the proposed controller is verified in actual experiments on a specially designed experimental QSL. [ABSTRACT FROM AUTHOR]

[Display omitted] • Extreme gradient boosting (XGBoost) is a novel and promising modelling framework for advanced schistosomiasis prognostication. • Haemostatic abnormalities and severe impairment of liver function strongly indicate the 1 year unfavourable prognosis. • Ascitic fluid volume is a key prognostic factor for advanced schistosomiasis. Short-term prognosis of advanced schistosomiasis has not been well studied. We aimed to construct prognostic models using machine learning algorithms and to identify the most important predictors by utilising routinely available data under the government medical assistance programme. An established database of advanced schistosomiasis in Hunan, China was utilised for analysis. A total of 9541 patients for the period from January 2008 to December 2018 were enrolled in this study. Candidate predictors were selected from demographics, clinical features, medical examinations and test results. We applied five machine learning algorithms to construct 1 year prognostic models: logistic regression (LR), decision tree (DT), random forest (RF), artificial neural network (ANN) and extreme gradient boosting (XGBoost). An area under the receiver operating characteristic curve (AUC) was used to evaluate the model performance. The important predictors of the optimal model for unfavourable prognosis within 1 year were identified and ranked. There were 1249 (13.1%) cases having unfavourable prognoses within 1 year of discharge. The mean age of all participants was 61.94 years, of whom 70.9% were male. In general, XGBoost showed the best predictive performance with the highest AUC (0.846; 95% confidence interval (CI): 0.821, 0.871), compared with LR (0.798; 95% CI: 0.770, 0.827), DT (0.766; 95% CI: 0.733, 0.800), RF (0.823; 95% CI: 0.796, 0.851), and ANN (0.806; 95% CI: 0.778, 0.835). Five most important predictors identified by XGBoost were ascitic fluid volume, haemoglobin (HB), total bilirubin (TB), albumin (ALB), and platelets (PT). We proposed XGBoost as the best algorithm for the evaluation of a 1 year prognosis of advanced schistosomiasis. It is considered to be a simple and useful tool for the short-term prediction of an unfavourable prognosis for advanced schistosomiasis in clinical settings. [ABSTRACT FROM AUTHOR]

Cyber security has become a serious concern as the internet penetrates every corner of our life over the last two decades. The rapidly developing human–machine interfacing calls for an effective and continuous authentication solution. Herein, we developed a two-factor, pressure-enhanced keystroke-dynamics-based security system that is capable of authenticating and even identifying users through their unique typing behavior. The system consists of a rationally designed triboelectric keystroke device that converts typing motions into analog electrical signals, and a support vector machine (SVM) algorithm-based software platform for user classification. This unconventional keystroke device is self-powered, stretchable and water/dust proof, which makes it highly mobile and applicable to versatile working environments. The promising application of this novel system in the financial and computing industry can push cyber security to the next level, where leaked passwords would possibly be of no concern. [ABSTRACT FROM AUTHOR]

Advanced schistosomiasis has become a major public health problem in areas with a heavy burden of schistosomiasis infection. Our objective was to determine the incidence and prevalence of advanced schistosomiasis and risk factors associated with case fatality of advanced schistosomiasis. Data were abstracted from hospitalization records of patients with advanced schistosomiasis from Hunan Province, China. The incidence and prevalence of advanced schistosomiasis were determined and the risk factors for death in advanced patients were assessed using logistic regression analysis. A total of 10,362 patients with advanced schistosomiasis were recruited into our study and 65% of them were categorized as the ascites type. There were 1249 deaths between 2005 and 2018 and the case fatality was 12.05%. The incidence of advanced schistosomiasis increased from 2002 to 2010, peaked in 2010 and then leveled off. The prevalence of advanced schistosomiasis increased from 2005 to 2014, and was stable afterwards. HBV was a risk factor for death in advanced patients (adjusted odds ratio (aOR=1.93, 95% confidence interval (CI: 1.55 to 2.41). Patients without splenectomy had a higher risk of death (aOR=1.29, 95%CI: 1.08 to 1.56). Upper gastrointestinal bleeding was positively associated with the risk of death (aOR=1.42, 95% CI: 1.15 to 1.76). Besides, abnormal ALT, ascites and anemia were also significantly associated with the risk of death in advanced patients. Advanced schistosomiasis was effectively controlled in recent years. Splenectomy could reduce the case fatality of advanced patients. HBV infection, abnormal ALT, upper gastrointestinal bleeding and anemia also predicted the risk of death for advanced patients. [ABSTRACT FROM AUTHOR]