•The entire model is composed of the NN static submodel and the linear dynamic submodel.•Duhem model is used to construct a neural network for hysteresis description and parameter identification.•The ...result reveals the proposed approach can precisely model and identify the actuator response.
Duhem model has been widely used to describe the hysteresis property for many memory-type nonlinear systems. In this paper, a novel parameter identification method based on artificial neural network has been developed for the Duhem hysteresis model. With the Duhem differential equation, a neural network is constructed reasonably whose weights are specially designed mapping to the model parameters. Based on the universal function approximation capability of neural network, the model parameters can be identified with the proposed approach by network training. The parameter identification scheme is validated by simulation firstly and then applied to modeling the piezoelectric actuator. The results reveal that the proposed identification approach can identify the static hysteresis nonlinearity with high accuracy. Furthermore, combined with the dynamic component, the presented method can also be used to describe the dynamic hysteresis of the piezoelectric actuator.
•An asymmetric Bou–Wen model is constructed by using a polynomial-based non-lag component.•A modified DE algorithm with global and local search ability is proposed for parameter ...identification.•Performance of proposed MDE is compared with classical DE and PSO algorithms.
A novel modified Bouc–Wen (MBW) model is presented in this paper to describe the asymmetric hysteresis of piezoelectric actuator, and the parameter identification method is proposed based on a novel modified differential evolution (MDE) algorithm. In the MBW model, a polynomial-based non-lag component is used to realize the asymmetric hysteresis property. In the proposed MDE algorithm, a comprehensive trial vector generation strategy and the initial control parameters are investigated to balance the global and local search ability. The MDE-based parameter identification is compared with the classical differential evolution algorithm and the particle swarm optimization algorithm. The results demonstrate that the proposed MDE is superior to its competitors for identifying the asymmetric hysteresis of piezoelectric actuator.
A multi-residue method was developed for rapid determination of pesticide residues in tea by ultra performance liquid chromatography–electrospray tandem mass spectrometry (UPLC/MS/MS). The QuEChERS ...method was used for sample preparation. In order to minimise the matrix effects from tea, a solid phase extraction (SPE) cartridge layered with graphite carbon/aminopropylsilanized silica gel was applied as complementary to QuEChERS method. For accurate quantification, representative matrix-matched calibration curves were applied to compensate matrix effects. Limits of quantification varied with different pesticides but all can be measured at 0.01
mg
kg
−1 level in a 5
g tea sample except dichlorvos (0.02
mg
kg
−1). Recoveries ranged from 70% to 120% and relative standard deviation (RSD) met the European United Quality Control guideline. Efficiency and reliability of this method were investigated by the analysis of both fermented and unfermented Chinese tea samples.
The sudden deterioration of patients with novel coronavirus disease 2019 (COVID-19) into critical illness is of major concern. It is imperative to identify these patients early. We show that a deep ...learning-based survival model can predict the risk of COVID-19 patients developing critical illness based on clinical characteristics at admission. We develop this model using a cohort of 1590 patients from 575 medical centers, with internal validation performance of concordance index 0.894 We further validate the model on three separate cohorts from Wuhan, Hubei and Guangdong provinces consisting of 1393 patients with concordance indexes of 0.890, 0.852 and 0.967 respectively. This model is used to create an online calculation tool designed for patient triage at admission to identify patients at risk of severe illness, ensuring that patients at greatest risk of severe illness receive appropriate care as early as possible and allow for effective allocation of health resources.
Community structure detection in a complex network structure and function is used to understand network relations and find its evolution rule; monitoring and forecasting its evolution behavior have ...an important theoretical significance; in the epidemic monitoring, network public opinion analysis, recommendation, advertising push and combat terrorism, and safeguard national security, it has wide application prospect. A label propagation algorithm is one of the popular algorithms for community detection in recent years; the community detection algorithm based on tags that spread the biggest advantage is the simple algorithm logic, relative to the module of optimization algorithm, convergence speed is very fast, the clustering process without any optimization function, and the initialization before do not need to specify the number of complex network community. However, the algorithm has some problems such as unstable partitioning results and strong randomness. To solve this problem, this paper proposes an unsupervised label propagation community detection algorithm based on density peak. The proposed algorithm first introduces the density peak to find the clustering center, first determines the prototype of the community, and then fixes the number of communities and the clustering center of the complex network, and then uses the label propagation algorithm to detect the community, which improves the accuracy and robustness of community discovery, reduces the number of iterations, and accelerates the formation of the community. Finally, experiments on synthetic network and real network data sets are carried out with the proposed algorithm, and the results show that the proposed method has better performance.
Superhydrophobic cotton fabrics consisting of tea polyphenol/Fe hybrid coatings on cotton fabrics (TP/Fe@cotton fabrics) were fabricated via a facile, highly efficient, and environmentally friendly ...method. No fluorinated substances or organic solvents were used in the preparation process that involved only Fe
2+
, natural substances, and water. The original and modified cotton fabrics were characterized by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. A coating with a uniform 3D bulge-like form and many closely arranged microparticles was coated onto the surface of the TP/Fe@cotton fabric. Compared to the original cotton fabric, the TP/Fe@cotton fabric showed a higher superhydrophobicity, with a water contact angle of approximately 161° and sliding angle about 15°. The TP/Fe@cotton fabric could withstand 1000 cycles of abrasion without an apparent decrease of the contact angle, and was also stable under a variety of harsh environmental conditions. In addition, the TP/Fe@cotton fabric demonstrated an excellent self-cleaning performance and a highly efficient separation of various oil–water mixtures. Furthermore, its separation performance remained excellent even under harsh conditions or after being reused ten times. This facile, highly efficient, and environmentally friendly preparation method has potential prospects for industrialization, and the superhydrophobic TP/Fe@cotton fabric has potential value in practical applications such as oil–water separation.
Copper (Cu) is a trace mineral nutrient essential for plant growth; consequently, its uptake, trafficking, and redistribution are precisely controlled. Currently, little is known about the underlying ...regulatory mechanisms in rice. In this work, we identified OsHIPP24 as a Cu metallochaperone in rice. Heterologous expression of
OsHIPP24
in wild-type yeast (
Saccharomyces cerevisiae
) strain BY4741 increased accumulation of Cu, as well as cadmium (Cd).
OsHIPP24
was expressed constitutively in most tissues of rice, including root, stem, leaf, leaf sheath, internode, rachis, and spikelet, and particularly high in root stele along with the vascular bundle of the shoot. Overexpression or knockout of
OsHIPP24
in rice led to stunted growth and reduced plant height, regardless of Cu levels in the growth medium. Taken together, these observations indicated that the physiological roles of OsHIPP24 involve the delivery of metal micronutrients via vascular tissues, and that OsHIPP24 plays a crucial role in the growth of rice.
The physicochemical properties of ink-jet printing ink are determined by the microstructure ((a) hydrogen bond and (b) three-dimensional structure) between the reagents. The existence of ...hydrogen-bonded water (T21), bound water (T22), and free water (T23) (c) in ink were further clarified. The normal ejection of ink (d) depends on the physicochemical properties of the ink and the driving waveform (e) loaded on the piezoelectric nozzle.
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•Research on geometry optimization and frequency calculation of intermolecular interactions of ink core reagents based on DFT.•Use DFT, LF-NMR and SEM to further clarify the effect of ink microstructure on the macroscopic properties (viscosity, mobility) of ink.•The optimized driving waveform of piezoelectric nozzle is suitable for the corresponding ink.•The development of ink and piezoelectric inkjet driving waveform design can get rid of blindness.
In this paper, we use density functional theory (DFT) to optimize and calculate the geometries and vibration frequencies of H2O, EG (ethylene glycol) or H2O/EG in the ink (B3LYP/6-311++G** basis set, self-consistent reaction field theory (SCRF) and PCM polarization unified field model). LF-NMR (low-filed nuclear magnetic resonance) further confirmed the weak interaction between H2O, EG or H2O/EG molecules, which had a decisive influence on the viscosity and mobility of ink. According to the analysis of the peak of the inversion spectrum (T22) of the ink, the viscosity of the ink increases with the left shift of the relaxation time. The inkjet performance of the ink is closely related to the physicochemical properties of the ink and the driving waveform of the piezoelectric nozzle. Exploration of the sharpness of the inkjet printing pattern that the microstructure and weak intermolecular interaction of the ink bounds the mobility of the solvent in the ink, which increases the viscosity of the ink (3.28-5.11 mPa.s), and the ink overcomes the capillary effect of the fabric, which makes the diffusion of the ink in the fabric decrease (7.23-3.91 %).
Nanofiltration (NF) with advantages of high efficiency and low‐cost has attracted increasing attentions in bio‐separation. However, the large‐scale application is limited by the inferior molecular ...selectivity, low chemical stability and serious membrane fouling. Many efforts, thus, have been devoted in NF materials design for specific applications to enhance the separation efficiency of bio‐products and increase membrane life‐time, as well as reduce the operating cost. This review summarized the recent progress of NF applications in bio‐separation, discussed various demands for NF membrane in the bio‐products purification and corresponding material innovations, finally proposed several practical suggestions for future research, which provided directions and guidance toward further product development and process industrialization.
Particulate matter (PM) pollution has posed great threat to human health. This calls for versatile protection or treatment devices that are both efficient and easy to use. Herein, we have rationally ...designed a novel reusable bilayer fibrous filter consisting of electrospun superhydrophobic poly(methylmethacrylate)/polydimethylsiloxane fibers as the barrier for moisture ingression and superhydrophilic chitosan fibers for a PM capture efficiency of over 96% at optical transmittance of 86%. Furthermore, it could realize a high-level PM2.5 capture efficiency (>98.23%) even after 100-h test during extremely hazardous air environment (PM2.5 > 3,000 μg m−3) and retain a high PM removal efficiency (PM2.5 > 98.39%) after five washing cycles. Besides, such membranes possessed high antibacterial activity at 96.5% for E. coli and 95.2% for Staphylococcus aureus. As a proof-of-concept study, continuous particle removing has been successfully demonstrated on a window screen to prevent particle pollution.
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•The superhydrophilic chitosan fibers play the role of enhanced removal capability•Superhydrophobic PDMS/PMMA fibers prevent water accumulation inside the membrane•Nanofibrous filters present excellent antibacterial property due to the chitosan component•Robust filters exhibit good recyclable performance for sustainable PM capturing
Materials Characterization; Nanomaterials; Pollution
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