bluuebunny/crossref_metadata_2025_split huggingface dataset:
Robust PIλ controller design for AUV motion control with guaranteed frequency and time domain behaviour
Authors: Liu L. , Zhang L. , Zhang S. 
Published: December 2020

AbstractAutonomous underwater vehicles require a motion control system for performing underwater tasks such as exploring and developing marine resources. This study proposes a fractional‐order proportional‐integral () controller for autonomous underwater vehicles motion control that simultaneously guarantees frequency and time domain behaviour. First, a stabilisation process is presented for the controlled system, and a three‐dimensional stable surface is obtained. Subsequently, the controller parameters can be tuned. Then, to guarantee frequency and time domain control performance simultaneously, the frequency domain behaviour is studied through a modified flat phase property, and the time domain behaviour is improved through parameter optimisation. The set‐point regulation and noise suppression performances of the autonomous underwater vehicles motion control system indicate that the proposed controller provides more flexibility in improving the system's robustness and transient performance.
Membership‐function‐dependent approach to design filter for non‐linear systems with time‐varying delay via interval type‐2 fuzzy model
Authors: Ran Guangtao , Li Chuanjiang 
Published: December 2020

AbstractThis paper addresses the problem of filtering for non‐linear systems with time‐varying delay via the interval type‐2 (IT2) fuzzy model and the membership‐function‐dependent approach. By taking the time‐varying delay and uncertainties into consideration, the non‐linear plant is modelled as an IT2 fuzzy delayed system, which fully captures the parameter uncertainties of the systems by using upper and lower membership functions. An IT2 fuzzy filter is designed to estimate the unknown information of the non‐linear systems, which does not require the same premise variables as the plant. By combining the IT2 fuzzy delayed system and the IT2 fuzzy filter, a filtering error system is established. Based on the Lyapunov theory, a fuzzy‐dependent Lyapunov function is constructed. Then, the membership‐function‐dependent approach, delay analysis approach, and some slack matrix variables are employing to analyse the derivative terms of the Lyapunov function, and a less conservative condition is derived to guarantee the filtering error system is stable. Moreover, the standard conditions of the filter are given in the form of linear matrix inequalities via the matrix decoupling technique. Finally, a numerical example is given to demonstrate the effectiveness and merits of the proposed method.
Audible noise spectral characteristics of high‐voltage ac bundled conductors at high altitude
Authors: He Wangling , Wan Baoquan , Liu Yunpeng , Liu Xingfa , Huang Shilong , Zhang Yinlu , Zhang Jiangong 
Published: December 2020

AbstractAt high altitudes, the corona discharge around a conductor surface is severe, and the induced audible noise (AN) is irritating; this is due to the low air density at high altitudes. Therefore, AN has become a crucial limiting factor in the design of ac power lines of 500 kV or higher at high altitudes. An investigation of the spectral characteristics of AN should help provide a greater understanding of corona noise; however, only a few studies have investigated the spectral characteristics of AN in practical bundled conductors at high altitude. Therefore, it is difficult for power utility companies to select suitable conductors. In this study, the AN spectral characteristics of 6 × LGJ400, 6 × LGJ720, and 8 × LGJ500 bundled conductors were investigated using an ultra‐high‐voltage corona cage (8 × 8 × 35 m) in Xining, Qinghai Province (altitude: 2261 m). The AN equivalent A‐weighted level and the 1/3‐octave frequency characteristics of these three conductors were obtained, and the influence of the electric field (E‐field) on these characteristics was analysed. Subsequently, the relationship between the AN A‐weighted level and the 8‐kHz level was examined. We found that, with the increase of the E‐field, the low‐frequency components of AN level did not exhibit an obvious trend, but in the high‐frequency band (1.6–20 kHz), a clear positive correlation was observed between the spectrum level and E‐field strength. Among these three conductors, the 8 × LGJ500 conductor was the optimal conductor for reducing the AN levels at high altitude. The results obtained in this study can provide a data reference for the construction of high‐altitude ac power lines.
An adaptive level set method based on joint estimation dealing with intensity inhomogeneity
Authors: Zhu Jiang , Zeng Yan , Li Jianqi , Tian Shujuan , Liu Haolin 
Published: December 2020

AbstractAutomatic object segmentation has been a challenging task due to intensity inhomogeneity. The traditional way is to eliminate the intensity inhomogeneity, which causes the object to lose useful intensity information. The authors propose an adaptive level set method for the segmentation of intensity inhomogeneous images. Firstly, global and local features are utilised to collaboratively estimate the image, which devotes to compensating for intensity inhomogeneity. The local estimation retains detailed spatial information, and the global estimation mainly contains the regional information of the partitioned object. Then, during the construction of the energy functional, joint estimation is introduced to create the external energy. To acquire the precise location of the boundary, a weighting factor indicated by the gradient is introduced into the internal energy. Finally, after the numerical calculation of the energy functional by additive operator splitting algorithm, this method achieves the desired performance in terms of accuracy and robustness. Experimental results verify this method outperforms the comparative methods and can be applied to many real‐world scenarios.
Facile fabrication of sodium carboxymethyl cellulose/reduced graphene oxide composite hydrogel and its application for Pb(II) removal
Authors: Zhang Yakun , Huang Runmin , Yu Jingang , Jiang Xinyu 
Published: December 2020

AbstractThe sodium carboxymethyl cellulose/reduced graphene oxide (rGO‐CMC) composite hydrogel was fabricated via environmental friendly one‐step hydrothermal reduction method. The morphology, pore structure and surface properties of the as‐prepared sample were characterized by scanning electron microscopy, Brunauer–Emmett–Teller surface area measurement and zeta potential analyser, respectively. To investigate the adsorption behaviour of rGO‐CMC for Pb(II), effects of contact time, temperature, initial concentration and pH were studied in detail. The rGO‐CMC composite before and after adsorption of Pb(II) was analysed by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy to further explore adsorption mechanism. Compared with rGO, the adsorption capacities of rGO‐CMC‐3 composite for heavy metals including Pb(II), Cu(II), Ni(II), Mn(II), Co(II) were increased to 156.85, 35.70, 21.40, 20.85 and 15.80 mg g−1, respectively. In addition, the rGO‐CMC composite formed a complete aerogel after freeze‐drying, which confirms its great potential as an easily separable adsorbent to remove heavy metals in aqueous solutions.
A membrane raindrop generator and its application as a self‐powered pH sensor
Authors: Chen Chunxu , Xie Guangzhong , Yao Mingliang , Pan Hong , Su Yuanjie 
Published: December 2020

AbstractRaindrop contains a large amount of renewable mechanical energy. Acid rain has adverse impact on the plants, aquatic animals and infrastructure. In this work, a triboelectric raindrop generator (TRG) was developed to harvest raindrop energy on a large scale. The TRG consists of electrification layer, electrodes and substrate. At the rainfall rate of 53 mL/s, the open‐circuit voltage and short‐circuit currents of the device reaches 27 V and 4.6 μA, respectively, which can simultaneously drive 60 LED light‐emitting diodes or charge a 5 μF capacitor. In addition, relied on the electrostatic shielding effect of the solid–liquid interface, the pH value of ambient solution drops can be spontaneously detected to reveal the potential in real‐time monitoring of environmental quality. By integrating with a signal processing circuit, a self‐powered acid rain alert system was formed for real‐time monitoring the acidity of the falling raindrops. This work proposes a feasible and innovative approach for active environmental monitoring.
Preparation of (CaY)F2:Tm3+,Yb3+ deposited porous TiO2 matrix with highly near‐infrared light photocatalytic activity
Authors: Zhao Xiaoyan , Kang An , Zhou Linxi , Zhou Huan , Qi Qianyu , Wang Hongshui , Xu Defeng , Liang Chunyong 
Published: December 2020

AbstractPorous titanium dioxide (TiO2) matrix deposited with upconversion luminescence agent (CaY)F2:Tm3+,Yb3+ was sol–gel prepared using polymethyl methacrylate (PMMA) microspheres as sacrificing template and tetrabutyl titanate as TiO2 precursors. The resulted photocatalysts were subsequently characterized by X‐ray diffraction, scanning microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, photoluminescence spectra (PL) etc. The photocatalytic activity and biocompatibility of TiO2/(CaY)F2:Tm3+,Yb3+ were evaluated by photocatalytic degradation of methyl orange (MO) and fibroblast cytotoxicity analysis, respectively. The results revealed that (CaY)F2:Tm3+,Yb3+ nanoparticles were well dispersed onto the pore walls of porous TiO2 matrix to generate a biocompatible composite. In addition, TiO2/(CaY)F2:Tm3+,Yb3+ was found to show excellent photocatalytic activity in both UV and infrared spectra, highlighted with the fact that (CaY)F2:Tm3+,Yb3+ nanocrystals can be excited to release UV light under near infrared light source, which can in consequence active TiO2. When the mass ratio of TiO2 to (CaY)F2:Tm3+,Yb3+ nanocrystals is 2:1, the best photocatalytic efficiency can be achieved with most of UV light released by (CaY)F2:Tm3+,Yb3+ absorbed by TiO2 to induce photo‐oxidation. The outstanding photocatalytic performance along with its biocompatibility, makes TiO2/(CaY)F2:Tm3+,Yb3+ a promising candidate in environmental and biomedical applications.
Nano‐MgO prepared via templating on biodegradable filter paper
Authors: Chen Hukui , Mu Xiaxia , Jiang Yu , Huang Jie , Jiang Hongli , He Zhijun 
Published: December 2020

AbstractNano‐MgO was successfully fabricated by a facile, inexpensive, and environment‐friendly synthetic method using filter paper as a bio‐template. The influence of the concentration of raw material Mg(CH3COO)2·4H2O on the textural properties of nano‐MgO was investigated, and the as‐prepared nano‐MgO was characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X‐ray analysis, thermo gravimetric analysis, Fourier transform infrared spectroscopy. The results of the experiment show the synthetic MgO fibres are composed of 20 nm tiny particles with a surface area of 68.28 m2/g and a pore width of 13 nm. When the concentration of Mg(CH3COO)2·4H2O solution was 0.03 mol/L, the product MgO copied the micro‐morphology of the filter paper. In addition, the photocatalytic activity of the prepared sample was investigated, and the results showed that the nano‐MgO prepared by this method has a higher catalytic activity than that prepared without a template.
Fabrication of durable superamphiphobic PA‐66 fabrics with wear‐resistance performance
Authors: Wang Xuman , Zhang Caining 
Published: December 2020

AbstractSuperamphiphobic surfaces have broad application prospects. In order to obtain superamphiphobic surfaces with better wear‐resistance, a fluorine‐containing acrylate copolymer coating and montmorillonite (MMT) particles were coated on polyamide 66 (PA‐66) fabrics. Scanning electron microscopy and X‐ray photoelectron spectroscope were applied to investigate the morphology and chemical composition of PA‐66 fabrics. The prepared fabrics showed superhydrophobicity and superoleophobicity. Meanwhile, the fabrics possessed excellent mechanical durability and self‐cleaning performance. The as‐prepared fabrics could be applied in the super‐antiwetting and other areas.
A new trench gate field stop insulated gate bipolar transistor (IGBT) with a significant reduction in Miller capacitance
Authors: Liu Yan‐juan , Zhao Liang , Wang Lening , Wang Yupeng 
Published: December 2020

AbstractIn this paper, a new trench‐gate field‐stop insulated gate bipolar transistor (IGBT) structure having improved performances is proposed, investigated and compared with the properties of the conventional trench‐gate field‐stop IGBT. An npn structure is introduced to the gate trench in order to reduce the Miller capacitance and gate‐collector charge through the introduction of the two diode capacitances in series. The simulation results demonstrate that the proposed structure exhibits a significant improvement in the following two aspects, without degrading the other performances. The first is the reduction of the Miller capacitance by 92.0% and 48.3% at Vce = 0 V and Vce = 20 V, respectively and the second is the reduction in gate‐collector charge by 66.7%.
Facile synthesis of multifunctional m‐SiO2@ZnO nanocomposite employing biocompatible polymers for potential theranostic applications
Authors: Hassan Syed Mujtaba ul , Anis Tanzeela , Khurshid Ahmat , Shahzad Faisal , Iqbal Zafar , Ali Zhaid , Shah Attaullah , Ahmad Jamil , Mehmood Mazhar 
Published: December 2020

AbstractA multifunctional nanocomposite based on ZnO and mesoporous SiO2 is presented for potential biomedical applications. A simple modified hydrothermal method is used to synthesize PEG‐coated ZnO whereas mesoporous SiO2 was obtained through sol–gel method. Nanocomposite is obtained by stirring the two products in deionized water under slightly acidic conditions. Biocompatibility is introduced through surface coating of ZnO with polyethylene glycol and of SiO2 with chitosan. ZnO nanoparticles with particle size of 50–80 nm and mesoporous SiO2 with particle size of 600 nm are obtained in the final composite. The nanocomposite has island‐type coat of ZnO nanoparticles on submicron mesoporous SiO2 with photoluminescent properties and drug‐carrying ability.
Morphological investigation of carbon nanotube reinforced polyurethane foam to analyse its acoustical and non‐acoustical properties
Authors: Basirjafari Sedigheh 
Published: December 2020

AbstractAcoustic damping analysis for open‐cell polyurethane/carbon nanotube nanocomposite foam is presented. Carboxylic functionalized CNT is used as an energy decaying filler in the PU matrix. The acoustical behaviour and non‐acoustical properties of polyurethane/carbon nanotube nanocomposite foam are explained through its cell morphological properties. For this aim, cellular morphologies such as strut length, strut thickness, cell size, pore diameter, and reticulation rate of the samples are determined from field emission scanning electron microscopy images by using 'Image J' software. Therefore, the effects of adding the carboxylated CNTs with different loading fractions to the PU matrix on its morphological properties and thus on its sound absorption and non‐acoustical physical parameters such as thermal characteristic length and viscous characteristic length are determined and discussed from field emission scanning electron microscopy images. Thermal characteristic length and viscous characteristic lengths are calculated through Johnson–Champoux–Allard porous model from the morphological properties, which has been directly measured on the field emission scanning electron microscopy images. Large differences were observed in the cellular morphologies of the polyurethane/carbon nanotube nanocomposite foams compared with that of the pure PU foam. Results show that the prediction of the acoustical behaviour of the polyurethane/carbon nanotube nanocomposite foams based on their cellular morphologies is in good agreement with the direct measurement of their acoustical properties.
A novel single‐phase five‐level hybrid rectifier using two active switches
Authors: Ma Hui , Han Xiao , Wu Peng , Yin Hongpeng 
Published: December 2020

AbstractA novel single‐phase five‐level rectifier based on two active switches is presented. The proposed novel circuit topology, with two active switches and a split dc‐link, can produce a distinct five‐level voltage with a reduced number of active switches. This circuit operates in unitary power factor mode with imposing a sinusoidal grid‐side current with low total harmonic distortion (THD) and controlled dc‐link voltage, which can be used as a low‐cost active rectifier to improve the efficiency of ac‐to‐dc rectification. This paper describes the circuit topology, the principle of operation, the feature of the circuit topology and the double‐loop control strategy in detail. The operation efficiency of the proposed topology is analysed in detail to show its benefits compared to the traditional five‐level PFC typologies. An experimental prototype with 220 V AC input, 400 V output, 500 W rated power, and 97.3% output efficiency is built to validate the proposed rectifier under real conditions of operation. The simulation and experimental results show the correctness and good performance (unitary power factor operation, sinusoidal current with low THD and dc‐link voltage regulation) of the proposed single‐phase five‐level rectifier.
First self‐resonant frequency of power inductors based on approximated corrected stray capacitances
Authors: Lope Ignacio , Carretero Claudio , Acero Jesus 
Published: December 2020

AbstractInductive devices are extensively employed in power electronic systems due to their magnetic energy storage and power transfer capabilities. The current trend is towards increasing the frequency of operation in order to reduce the size of the magnetic components, but the main drawback is that the parasitic capacitance effect can become significant, and degrade the performance of the system. This work analyses the influence of this stray capacitance, and considers how to improve the performance of the device. In general, the impact of the stray capacitance on a magnetic component can be reduced by two methods: reducing the parasitic capacitance between turns of the winding or, alternatively, modifying the arrangement of the connection between turns. To evaluate the last option, an approximated expression of the first self‐resonant frequency of the magnetic device is proposed. This gives a rapid assessment of the performance of different devices maintaining the overall equivalent inductance. The proposed expression accounts for the influence of the connection between turns in the bandwidth of the component. Finally, some numerical results are verified with planar coils manufactured on two‐layer printed circuit boards.
Single‐phase wind‐BES microgrid with seamless transition capability
Authors: Gupta Tripurari Nath , Singh Bhim 
Published: December 2020

AbstractA new control strategy for a wind‐BES (battery energy storage) microgrid is presented, which controls the power transfer and the mode of operation seamlessly from an islanded mode (IM) to the grid connected mode (GCM) and vice versa. In GCM, the DC link voltage regulation, the load reactive power compensation and harmonics current mitigation are performed by the load side voltage source converter (LVSC) using a double sinusoidal signal integrator (DSSI) based control algorithm. The maximum power from the wind generation is extracted by operating the generator side voltage source converter (GSC). At the grid fault or grid disturbances, this microgrid operates in IM and LVSC is controlled in the voltage control mode. A synchronizing controller is utilized to control the operation of synchronization. The grid current and point of common coupling (PCC) voltage distortions are kept within the limit as per the IEEE‐519‐2014 and the IEEE‐1547 standards. The system operation is demonstrated through test results at several conditions such as, changing wind speeds, varying loads and seamless transition.
High performance current control of single‐phase grid‐connected converter with harmonic mitigation, power extraction and frequency adaptation capabilities
Authors: Somkun Sakda 
Published: December 2020

AbstractGrid‐connected converters in distributed generation systems are required to operate under highly distorted voltage with a wide frequency range, and to provide active/reactive power information for ancillary services and power control. This paper presents multiple unbalanced synchronous reference frame control for regulating and mitigating the grid current distortion of a voltage source converter caused by grid voltage distortion and converter deadtime. The proposed control technique has intrinsic power extraction and frequency adaptation capabilities. The multiple unbalanced synchronous reference frame control is compared with the proportional multi‐resonant control. A new controller which combines the unbalanced synchronous reference frame control for regulation of the fundamental component current and the multi‐resonant control for harmonic compensation is presented. The proposed control techniques were verified with a 1.5‐kVA LCL‐filtered grid connected inverter. The multiple unbalanced synchronous reference frame control with odd harmonic orders 3rd to 13th exhibited excellent harmonic rejection with a total harmonic distortion (THD) less than 0.60% under a highly distorted voltage. The proposed combined control technique provided slightly inferior performance with the grid current THD less than 0.65%. The combined control scheme retains functionalities as the multiple unbalanced synchronous reference frame control with a significant reduction of computational effort.
Analysis and improvement of fourth‐order generalised integrator based phase‐locked loop
Authors: Li Jinbo , Wang Qin , Xiao Lan , Lu Yichen , Wu Qunfang 
Published: December 2020

AbstractThe fourth‐order generalised integrator is very suitable for single‐phase phase‐locked loop because it can provide orthogonal signal conveniently and block harmonic voltages effectively. In the conventional fourth‐order generalised integrator based phase‐locked loop, the resonance frequency of fourth‐order generalised integrator needs to be adjusted according to the grid frequency. To improve the phase‐locked loop performance, a non‐adaptive fourth‐order generalised integrator is suggested for single‐phase system, and this paper presents a correction method. According to the estimated grid frequency, the amplitude imbalance and phase error caused by non‐adaptive fourth‐order generalised integrator can be calculated, and two adaptive units are added to deal with the problems. Moreover, the small‐signal model of the proposed phase‐locked loop is carried out, and the control parameters are tuned. Compared to conventional fourth‐order generalised integrator based phase‐locked loop, the proposed phase‐locked loop shows a better performance, which is verified through simulation and experimental results.