bluuebunny/crossref_metadata_2025 huggingface dataset:
One-dimensional and two-dimensional coordination polymers from cluster modular construction
Authors: Li Jie , Tan Yi , Cao Chen , Wang Zhi-Kang , Niu Zheng , Song Ying-Lin , Lang Jian-Ping
Published: March 2021

Cluster module construction of W/Cu/S cluster-based coordination polymers and their third-order NLO properties were investigated.
Mechanistic study of C–H bond activation by O2 on negatively charged Au clusters: α,β-dehydrogenation of 1-methyl-4-piperidone by supported Au catalysts
Authors: Miyazaki Ray , Jin Xiongjie , Yoshii Daichi , Yatabe Takafumi , Yabe Tomohiro , Mizuno Noritaka , Yamaguchi Kazuya , Hasegawa Jun-ya
Published: March 2021

Aerobic C–H activation by Au/OMS-2 catalyst is driven by charge transfer from OMS-2 to adsorbed O2via Au cluster.
Pyrolysis-free polymer-based oxygen electrocatalysts
Authors: Huang Bingyu , Li Longbin , Tang Xiannong , Zhai Weijuan , Hong Yaoshuai , Hu Ting , Yuan Kai , Chen Yiwang
Published: March 2021

This review summarizes the fundamental and recent progress in optimizing pyrolysis-free polymer-based oxygen electrocatalysts with clear structure–performance relationships. The challenges and future directions in this field are also discussed.
Lactiplantibacillus plantarum H-87 prevents high-fat diet-induced obesity by regulating bile acid metabolism in C57BL/6J mice
Authors: Liang Cong , Zhou Xiao-Hong , Gong Pi-Min , Niu Hai-Yue , Lyu Lin-Zheng , Wu Yi-Fan , Han Xue , Zhang Lan-Wei
Published: March 2021

Lactiplantibacillus plantarum H-87 shows excellent bile salt hydrolase activity in vitro and effectively prevents obesity by regulating bile acid metabolism to inhibit liver fat accumulation, insulin resistance and lipid digestion in C57BL/6J mice.
A robust and scalable active-matrix driven digital microfluidic platform based on printed-circuit board technology
Authors: Xing Yaru , Liu Yu , Chen Rifei , Li Yuyan , Zhang Chengzhi , Jiang Youwei , Lu Yao , Lin Bingcheng , Chen Peizhong , Tian Ruijun , Liu Xianming , Cheng Xing
Published: March 2021

An active-matrix digital microfluidic platform based on printed-circuit board technology is developed as a robust, highly scalable, low cost, easy to use, and contamination-insensitive device for automatic and parallel droplet handling.
Pb(ii) adsorption from aqueous solution by an aluminum-based metal organic framework–graphene oxide nanocomposite
Authors: Chowdhury Tonoy , Zhang Lei , Zhang Junqing , Aggarwal Srijan
Published: March 2021

The composites of metal–organic frameworks (MOF) and graphene oxide (GO) have demonstrated strong potential in removing Pb(ii) ions from industrial wastewaters.
Hairy silica nanosphere supported metal nanoparticles for reductive degradation of dye pollutants
Authors: Chen Xin , Zhang Li , Xu Bin , Chen Tingting , Hu Lianhong , Yao Wei , Zhou Mengxiang , Xu Hui
Published: March 2021

Highly dispersed and tiny-sized noble metal nanoparticles are deposited on a hairy poly(4-vinylpyridine)-silica support, which can serve as recyclable heterogeneous catalysts in the reductive degradation of 4-NP and RhB dye pollutants.
Antiferromagnetic spin ordering in two-dimensional honeycomb lattice of SiP3
Authors: Adhikary Souren , Dutta Sudipta , Mohakud Sasmita
Published: March 2021

Two-dimensional buckled honeycomb lattice of SiP3 shows antiferromagnetic coupling between triangular ferromagnetic domains, arising from the Fermi-instability of itinerant π-electrons.
A design strategy of ultrasmall Gd2O3 nanoparticles for T1 MRI with high performance
Authors: Yang Jianfeng , Shan Pengyuan , Zhao Qingling , Zhang Shuquan , Li Lanlan , Yang Xiaojing , Yu Xiaofei , Lu Zunming , Wang Ziwu , Zhang Xinghua
Published: March 2021

Proposing a design strategy of Gd3+ based nanoparticles for high performance magnetic resonance imaging.
A NiAg-graphene quantum dot-graphene hybrid with high oxidase-like catalytic activity for sensitive colorimetric detection of malathion
Authors: Dan Xu , Ruiyi Li , Qinsheng Wang , Yongqiang Yang , Haiyan Zhu , Zaijun Li
Published: March 2021

This paper reports the synthesis of a nickel-silver-graphene quantum dot-graphene hybrid.
Divorce in the two-component BVMO family: the single oxygenase for enantioselective chemo-enzymatic Baeyer–Villiger oxidations
Authors: Röllig Robert , Paul Caroline E. , Claeys-Bruno Magalie , Duquesne Katia , Kara Selin , Alphand Véronique
Published: March 2021

The oxygenase part of a two-component BVMO in combination with synthetic nicotinamide analogues does not require any reductase or expensive NAD(P)H.
Exploration of human xylosyltransferase for chemoenzymatic synthesis of proteoglycan linkage region
Authors: Gao Jia , Lin Po-han , Nick Setare Tahmasebi , Liu Kunli , Yu Kefei , Hohenester Erhard , Huang Xuefei
Published: March 2021

Human xylosyl transferase can effectively install a xylose stereospecifically onto a peptide backbone on mg scales paving the way for efficient chemoenzymatic synthesis of proteoglycan glycopeptides and glycoproteins.
Enhanced charge separation in TiO2/nanocarbon hybrid photocatalysts through coupling with short carbon nanotubes
Authors: Al Mayyahi Ahmed , Everhart Brian M. , Shrestha Tej B. , Back Tyson C. , Amama Placidus B.
Published: March 2021

The interfacial contact between TiO2 and graphitic carbon in a hybrid composite plays a critical role in electron transfer behavior, and in turn, its photocatalytic efficiency.
External electric field: a new catalytic strategy for the anti-Markovnikov hydrohydrazination of parent hydrazine
Authors: Zhang Ming-Xia , Li Wen-Zuo , Xu Hong-Liang , Zhou Zi-Yan , Zhuo Shu-Ping
Published: March 2021

The anti-Markovnikov hydrohydrazination of parent hydrazine were catalyzed by external electric field (EEF) to a large extent. Furthermore, the solvent effects and the substituent effects of the hydrohydrazination were enhanced in the presence of EEF.
Network pharmacology-based analysis for unraveling potential cancer-related molecular targets of Egyptian propolis phytoconstituents accompanied with molecular docking and in vitro studies
Authors: Ibrahim Reham S. , El-Banna Alaa A.
Published: March 2021

Multi-level mechanism of action of propolis constituents in cancer treatment using an integrated approach of network pharmacology-based analysis, molecular docking and in vitro cytotoxicity testing.
Theoretical hydrogen bonding calculations and proton conduction for Eu(iii)-based metal–organic framework
Authors: Feng Lu , Zeng Tian-Yu , Hou Hao-Bo , Zhou Hong , Tian Jian
Published: March 2021

A water-mediated proton-conducting Eu(iii)-MOF has been synthesized, which provides a stable proton transport channel that was confirmed by theoretical calculation.
Plateau–Rayleigh instability in a soft viscoelastic material
Authors: Tamim S. I. , Bostwick J. B.
Published: March 2021

A soft cylindrical interface endowed with surface tension can be unstable to wavy undulations. The most unstable wavelength depends upon the viscoelastic properties of the material and is determined by a dynamic stability analysis.
Comprehensive analyses of the cysteine thiol oxidation of PKM2 reveal the effects of multiple oxidation on cellular oxidative stress response
Authors: Irokawa Hayato , Numasaki Satoshi , Kato Shin , Iwai Kenta , Inose-Maruyama Atsushi , Ohdate Takumi , Hwang Gi-Wook , Toyama Takashi , Watanabe Toshihiko , Kuge Shusuke
Published: March 2021

Redox regulation of proteins via cysteine residue oxidation is involved in the control of various cellular signal pathways. Pyruvate kinase M2 (PKM2), a rate-limiting enzyme in glycolysis, is critical for the metabolic shift from glycolysis to the pentose phosphate pathway under oxidative stress in cancer cell growth. The PKM2 tetramer is required for optimal pyruvate kinase (PK) activity, whereas the inhibition of inter-subunit interaction of PKM2 induced by Cys358 oxidation has reduced PK activity. In the present study, we identified three oxidation-sensitive cysteine residues (Cys358, Cys423 and Cys424) responsible for four oxidation forms via the thiol oxidant diamide and/or hydrogen peroxide (H2O2). Possibly due to obstruction of the dimer-dimer interface, H2O2-induced sulfenylation (-SOH) and diamide-induced modification at Cys424 inhibited tetramer formation and PK activity. Cys423 is responsible for intermolecular disulfide bonds with heterologous proteins via diamide. Additionally, intramolecular polysulphide linkage (–Sn–, n ≧ 3) between Cys358 and an unidentified PKM2 Cys could be induced by diamide. We observed that cells expressing the oxidation-resistant PKM2 (PKM2C358,424A) produced more intracellular reactive oxygen species (ROS) and exhibited greater sensitivity to ROS-generating reagents and ROS-inducible anti-cancer drugs compared with cells expressing wild-type PKM2. These results highlight the possibility that PKM2 inhibition via Cys358 and Cys424 oxidation contributes to eliminating excess ROS and oxidative stress.
Digital Twin models in industrial operations: State‐of‐the‐art and future research directions
Authors: Melesse Tsega Y. , Di Pasquale Valentina , Riemma Stefano
Published: March 2021

A Digital Twin is a virtual representation of a physical product, asset, process, system, or service that allows us to understand, predict, and optimise their performance for better business outcomes. Recently, the use of Digital Twin in industrial operations has attracted the attention of many scholars and industrial sectors. Despite this, there is still a need to identify its value in industrial operations mainly in production, predictive maintenance, and after‐sales services. Similarly, the implementation of a Digital Twin still faces many challenges. In response, a systematic literature review and analysis of 41 papers published between 2016 and 11 July 2020 have been carried out to examine recently published works in the field. Future research directions in the area are also highlighted. The result reveals that, regardless of the challenges, the role of Digital Twin in the advancement of industrial operations, especially production and predictive maintenance is highly significant. However, its role in after‐sales services remains limited. Insights are offered for research scholars, companies, and practitioners to understand the current state‐of‐the‐art and challenges, and to indicate future research possibilities in the field.
A comprehensive framework from real‐time prognostics to maintenance decisions
Authors: Jain Amit Kumar , Dhada Maharshi , Hernandez Marco Perez , Herrera Manuel , Parlikad Ajith Kumar
Published: March 2021

Studying the influence of imperfect prognostics information on maintenance decisions is an underexplored area. To bridge this gap, a new comprehensive maintenance support system is proposed. First, a survival theory‐based prognostics module employing the Weibull time‐to‐event recurrent neural network was deployed in which prognostics competence was enhanced by predicting the parameters of failure distribution. In conjunction with this, a new predictive maintenance (PdM) planning model was framed via a trade‐off between corrective maintenance and time lost due to PdM. This optimises maintenance time based on operational and maintenance cost parameters from the historical data. The performance of the proposed framework is demonstrated using an experimental case study on maintenance planning for cutting tools within a manufacturing facility. Systematic sensitivity analysis is provided, and the impact of imperfect prognostics information on maintenance decisions is discussed. Results show that uncertainty about prediction declines as time goes on, and as uncertainty declines, the maintenance timing becomes closer to the remaining useful life. This is expected, as the risk of making a wrong decision decreases over time.
On the switching control of the DC–DC zeta converter operating in continuous conduction mode
Authors: Sarkawi Hafez , Ohta Yoshito , Rapisarda Paolo
Published: March 2021

Here, a switching control mechanism for the stabilization of a DC–DC zeta converter operating in continuous conduction mode is proposed. The switching control algorithm is based on a control Lyapunov function and extends the method proposed for a two‐dimensional boost converter model presented in the literature to a four‐dimensional zeta converter model. The local asymptotical stability of the operating point is established using LaSalle's invariance principle for differential inclusions. By applying spatial regularization, a modified switching control algorithm reduces the switching frequency and keeps the state‐trajectory around a neighbourhood of the operating point. The method works well even if the operation point changes significantly and it is valid for both step‐up and step‐down operations. Furthermore, by approximating the state‐trajectory near the operating point, an explicit relation between the modified switching algorithm and the switching frequency is obtained, which allows to choose systematically the desired switching frequency for the converter to operate. The effectiveness of the proposed method is illustrated with simulation results.
The sliding mode control approach design for nonholonomic mobile robots based on non‐negative piecewise predefined‐time control law
Authors: Lin Lixiong , Wu Peixin , He Bingwei , Chen Yanjie , Zheng Jiachun , Peng Xiafu
Published: March 2021

In this paper, a novel trajectory tracking control method of nonholonomic mobile robots based on the non‐negative piecewise predefined‐time theorem is proposed. The idea of cascade control is used to divide the posture error system of the mobile robot into two subsystems. Firstly, for the first‐order subsystem, an active predefined‐time controller is designed to realize that the angle error system converges and stabilizes to zero within a given time, which is preset in advance. Secondly, a novel predefined‐time sliding mode controller is designed for the second‐order subsystem, which adds a constant to compensate for the influence of singularity. Moreover, compared with the existing fixed‐time control algorithm, the control scheme proposed in this paper provides a more accurate upper bound of the settling time estimation. For convenience, the complex expression of the settling time estimation is transformed into an adjustable parameter. Furthermore, the stability of the two developed controllers is analyzed and some conditions for selecting parameters are given. Finally, the simulation results show the feasibility and correctness of the proposed control algorithm.
Maximal‐ratio combining detection in massive multiple‐input multiple‐output systems with accurate probability distribution function
Authors: Chumchewkul Ditsapon , Tsimenidis Charalampos
Published: March 2021

This letter derives the probability distribution function (PDF) of received symbols for orthogonal frequency‐division multiplexing (OFDM) based massive multiple‐input, multiple‐output (MMIMO) systems, which uses maximal‐ratio combining (MRC) detection. The effects of noise and interferences are evaluated through random variables, and the PDF is then derived from their joint probability and characteristic functions. The bit error rate (BER) using Binary and Quadrature Phase Shift Keying (BPSK, QPSK), and M‐ary Quadrature Amplitude Modulation (QAM) waveforms is then analyzed by using this PDF. Simulation and analytical results confirm that the derived equations provided accurate PDF and BER, and therefore, can be used efficiently to evaluate performance of OFDM‐MMIMO systems.
Bandwidth comparison of rectangular and offset cross‐slot frequency‐selective surface polarisation transformers
Authors: Clendinning Sarah , Cahill Robert , Zelenchuk Dmitry , Fusco Vincent
Published: March 2021

This letter compares the 3 dB axial ratio (AR) bandwidth (BW) of transmission mode single‐screen linear‐to‐circular polarisation convertors based on three different slot topologies. Using a conventional centre‐connected cross‐slot arrangement as a baseline, we show that a significant performance improvement can be achieved by creating a more elaborate design with unit cells composed of multiple unequal length offset rectangular‐shaped apertures. The additional flexibility to tailor the shape of the Transverse Electric (TE) and Transverse Magnetic (TM) spectral amplitude and phase responses is exploited to achieve an 84% increase in the BW relative to the baseline for a freestanding structure, which is designed to work at a centre frequency of 10.0 GHz. Experimental AR results are used to verify the new design methodology.
Computationally efficient predictive torque control for induction motor drives based on flux positional errors and extended Kalman filter
Authors: Abbasi Muhammad Abbas , Husain Abdul Rashid , Nik Idris Nik Rumzi , Fasih ur Rehman Syed Muhammad
Published: March 2021

This paper proposes an improved model based predictive torque control (MPTC) method based on positional error between reference and estimated stator flux vectors. The main advantages of the proposed method are: the improved computational efficiency which requires minimum hardware resources and weighting‐factor‐free cost function. Weighting factor is removed by using modified reference transformation, which converts torque reference into equivalent stator flux reference. Improvement in computational performance is achieved by using decreased number of voltage vectors for prediction. An admissibility criterion based on flux positional errors is introduced to reduce the number of voltage vectors. The computational time saved is utilised to incorporate extended Kalman filter for better estimation of flux and torque. The validity of the proposed method is tested on a two‐level three‐phase inverter fed induction motor drive with dSpace DS1104 as controller board. The dynamic response and computational cost of the proposed method is compared to other established MPTC methods. The superiority of the proposed technique is confirmed by experimental results, which show an average of 32% reduction in computational time when compared to conventional MPTC while comparable dynamic response in terms of torque ripple, flux ripple and load current harmonics, is also maintained.
Extracting spatially global and local attentive features for rolling bearing fault diagnosis in electrical machines using attention stream networks
Authors: Karnavas Yannis L. , Plakias Spyridon , Chasiotis Ioannis D.
Published: March 2021

A health diagnosis mechanism of rolling element bearings is necessary since the most frequent faults in rotating electrical machines occur in the bearing parts. Recently, convolutional neural networks (CNNs) have redefined the state‐of‐the‐art accuracy for bearing fault detection and identification, extracting location invariant feature mappings without the need for prior expert knowledge. With the use of convolution operations as the core of the process, CNNs consider the local spatial coherence of the input. However, one major drawback of the convolutional models is the weakness to capture global information about the input vector and to derive knowledge about the statistical properties of the latter. The authors propose a deep learning (DL) model that concatenates the features that are produced from two neural streams. Each consists of an attention mechanism that intends to learn different representations of the input vector, and so finally to produce a feature mapping that contains global and spatial locally information. Simulation results on two famous rolling element bearings fault detection benchmarks show the effectiveness of the method. In particular, the proposed DL model achieves 99.60% in the Case Western Reserve University bearing data set and 99.10% in the Paderborn University bearing data set.
Silicon circuits for chip‐to‐chip communications in multi‐socket server board interconnects
Authors: Moralis‐Pegios Miltiadis , Pitris Stelios , Mitsolidou Charoula , Fotiadis Konstantinos , Ramon Hannes , Lambrecht Joris , Bauwelinck Johan , Yin Xin , Ban Yoojin , De Heyn Peter , Van Campenhout Joris , Lamprecht Tobias , Lehnman Andreas , Pleros Nikos , Alexoudi Theoni
Published: March 2021

Multi‐socket server boards (MSBs) exploit the interconnection of multiple processor chips towards forming powerful cache coherent systems, with the interconnect technology comprising a key element in boosting processing performance. Here, we present an overview of the current electrical interconnects for MSBs, outlining the main challenges currently faced. We propose the use of silicon photonics (SiPho) towards advancing interconnect throughput, socket connectivity and energy efficiency in MSB layouts, enabling a flat‐topology wavelength division multiplexing (WDM)‐based point‐to‐point (p2p) optical MSB interconnect scheme. We demonstrate WDM SiPho transceivers (TxRxs) co‐assembled with their electronic circuits for up to 50 Gb/s line rate and 400 Gb/s aggregate data transmission and SiPho arrayed waveguide grating routers that can offer collision‐less time of flight connectivity for up to 16 nodes. The capacity can scale to 2.8 Gb/s for an eight‐socket MSB, when line rate scales to 50 Gb/s, yielding up to 69% energy reduction compared with the QuickPath Interconnect and highlighting the feasibility of single‐hop p2p interconnects in MSB systems with >4 sockets.
Co‐packaged datacenter optics: Opportunities and challenges
Authors: Minkenberg Cyriel , Krishnaswamy Rajagopal , Zilkie Aaron , Nelson David
Published: March 2021

High‐capacity, high‐density, power‐, and cost‐efficient optical links are undoubtedly of critical importance for datacenter infrastructure. However, the optics roadmap has come to a fork in the road: Is it right to continue on the tried and proven path of pluggable modules or is it time to adopt a new deployment model that involves co‐packaged optics? Herein, we aim to shed light on the trade‐offs involved, enabling technologies, paths to adoption, and potential impact on datacenter network architecture.
Transient and steady‐state study of a speed sensorless IPMSM drive with an advanced integrator‐based stator flux estimator
Authors: Sharma Toshi , Bhattacharya Avik , Ahmed Haris
Published: March 2021

In this paper, an advanced integrator is proposed for the estimation of stator flux in a direct torque control (DTC) drive. A two‐level lookup table‐based direct torque‐controlled interior permanent magnet synchronous motor (IPMSM) drive is implemented. DTC has the inherent disadvantage of DC drift and saturation in stator flux estimation due to a pure integrator. In the proposed work, a different approach to estimate stator flux is reported overcoming the constraints of a pure integrator in DTC. An advanced integrator with an adaptive controller is implemented to determine the stator flux and enrich the performance of the drive. A comparison of transient and steady‐state analysis is carried out when IPMSM is fed by a low‐pass filter‐based DTC and proposed stator flux estimator‐based DTC. To make the system mechanically robust, stator current‐based model reference adaptive control is executed to estimate the motor speed. A mathematical derivation for the stability study of the adaptation mechanism is carried out using Popov's hyperstability criteria. The proposed algorithm is implemented in the MATLAB/Simulink environment and the soundness of the proposed work is presented by simulation results. Moreover, the experimental analysis using dSPACE1104 justifies the simulation results of the proposed system.
Arm current reversal‐based modular multilevel DC‐DC converter
Authors: Nazih Yousef , Hossam‐Eldin Ahmed , Elserougi Ahmed
Published: March 2021

Nowadays, most of the converters used in high‐power high‐voltage (HV) applications are the conventional modular multilevel converters (MMC). However, in the case of DC‐DC conversion, an imbalance of the capacitor voltages occurs and the conventional MMC fails to operate correctly. This paper introduces an arm current reversal‐based modular multilevel DC‐DC converter, which successfully provides balance among the capacitor voltages while operating in DC‐DC conversion. The proposed configuration is used in medium voltage DC grids to feed DC loads or to interconnect between two DC grids of different voltage levels. The proposed converter is a two‐stage DC‐DC modular converter, which consists of a single‐phase half‐bridge MMC with half‐bridge submodules (HBMMC) followed by a single‐phase H‐bridge MMC with half‐bridge submodules (SMs). The operational concept of the proposed converter is based on reversing the arm current direction and reversing the output terminals with the help of the H‐bridge MMC stage, which ensures the same direction of the voltage at the load terminals. The proposed converter provides a high conversion ratio, bidirectional power flow, simple architecture, and a simple control scheme. Detailed illustrations, analysis, and design of the proposed converter are presented. Besides, MATLAB‐based and Opal RT‐based simulation results and experimental results are presented to validate the proposed configuration claims.
A novel active current co‐efficient extraction‐based control for grid‐tied solar photovoltaic system
Authors: Jalan Subham Kumar , Babu B. Chitti , Patel Nirav , Kumar Ajay , Gupta Nitin
Published: March 2021

In this paper, a novel active current co‐efficient extraction (ACCE)‐based control method is presented for a three‐phase grid‐interfaced voltage source inverter (VSI). Since the VSI performance largely depends on the reference current generation method, it is of significance to identify the active current co‐efficient of the load current contaminated with harmonics, as it is a key governing factor that decides the shape of the compensating current. The proposed ACCE structure functions with minimal mathematical operators like product, sum, and integrators and thereby identifies the fundamental current with computational effectiveness. Besides, in comparison to existing prevalent state‐of‐the‐art methods, the proposed ACCE structure is devoid of any low‐pass filter and zero‐crossing detector, and hence serves the following two distinctive purposes: (i) Ensures minimum steady‐state oscillations and (ii) exhibits improved dynamic performance under disturbances in the grid and load. The proposed structure effectively confronts the various power quality challenges while injecting the active power into the utility grid. Further, the incremental‐conductance‐based maximum power point tracking algorithm is equipped to extract the maximum possible power from the photovoltaic array. Finally, the effectiveness of the proposed ACCE structure has been investigated through MATLAB/Simulink software studies followed by dSPACE‐1104‐based experimental setup.
Generalized diamond‐type single DC‐source switched‐capacitor based multilevel inverter with step‐up and natural voltage balancing capabilities
Authors: Deliri Saeid , Varesi Kazem , Siwakoti Yam P. , Blaabjerg Frede
Published: March 2021

This paper proposes a diamond‐shaped high step‐up switched‐capacitor based basic multilevel inverter topology. The basic switched‐capacitor (SC) stage consists of 2 active switches, 2 diodes, and 2 capacitors. Using a single DC source with the unfolding circuit (10 switches, 5 capacitors, and 5 diodes) results in the production of 17 voltage‐steps at the output with the gain of up to 8 times of the input voltage. By extending the diamond‐shaped switched‐capacitor stages, higher voltage levels and voltage gains can be possible. The suggested topology employs two half‐bridges (instead of a full‐bridge) to produce positive, zero, and negative steps, which reduces the Voltage Stress (VS) on two output switches and consequently reduces Total Voltage Stress (TVS). In addition, the natural voltage balancing of capacitors eliminates the need to an additional control circuitry and consequently reduces the total converter size, complexity, and cost. In addition, modularity, scalability, low voltage ripple on capacitors, low total voltage stress, high power quality, and capability of supplying low/medium power factor (R‐L) loads are some of the merits of the proposed topology. The low Cost Function (CF) obtained in the comparison section as well as experimental results verifies the advantages of the proposed topology.
Day‐ahead wind power combination forecasting based on corrected numerical weather prediction and entropy method
Authors: Yang Mao , Dai Bozhi , Wang Jinxin , Chen Xinxin , Sun Yong , Li Baoju
Published: March 2021

To satisfy the grid operation scheduling requirements for wind power forecasting model accuracy, the measured wind speed near the height of the wind turbine hub is added to the wind power combined forecasting model. First, the relationship between the numerical weather prediction wind speed and the measured wind speed at different heights are analysed, and the correlation between each wind speed and the wind power is compared. Second, the random forest algorithm combined with the cumulative contribution rate is used to select several meteorological types of numerical weather prediction data as the input of the long short‐term memory network to predict wind speed. Third, while inputting the meteorological data provided by numerical weather prediction, which is highly related to wind power, the wind power prediction network also uses the predicted wind speed of the upper network as input to predict wind power. Finally, the entropy method is used to dynamically determine the combined weights of each forecasting model and improve the adaptability of the model. Research and analysis using measured data from two wind farms located in northeast China have verified the effectiveness of the method.
Fundamental study related to the development of modular solar panel for improved durability and repairability
Authors: Majdi Abdulrhman , Alqahtani Mohammed Dhafer , Almakytah Abdulmalik , Saleem Muhammad
Published: March 2021

Solar panels around the globe are primarily designed as a plug‐and‐play solution and the end users are not allowed to repair the panel in case of damage. Natural loadings such wind, snow, sand and hail can lead to irreparable damage to the solar panels and the easiest solution to fix the damaged solar panel is to replace it. This design philosophy leads to a huge quantity of electronic waste as it completely ignores the repairability of the solar panels. In this regard, the presented research work details the development and testing of modular solar panel with performance similar to the traditional design. The modular design was tested for power transfer, re‐connection upon impact and the ability to replace the selected parts in case of permanent damage without the need of replacing the entire solar panel. This experimental research work delivers a modular solar panel design that has ease of repairability in case of damage. Furthermore, a detailed economic analysis has been provided for several real‐world scenarios that indicate its suitability over existing commercially available solutions.
Design and optimisation of a bidirectional flux modulation machine for AC and DC power supplies
Authors: Qifang Lin , Niu Shuangxia , Wu Huihuan , Fu Weinong
Published: March 2021

This study proposes a novel power supply system that utilises wind power to produce AC and DC power. A special designed generator based on bidirectional flux modulation effect is the key part of the proposed power supply system. The novel power system has a compact structure since the proposed generator has two electric port. There are three essential points that make the proposed system outstanding. One is the contra‐rotating rotors, which will cluster wind power even under low wind speed. Second one is the dual armature winding structure, which will provide AC and DC power simultaneously. There are two electric port in the proposed generator. One port can produce AC power to the non‐sensitive resistive load. The other can provide AC power with different frequency to the rectifier to obtain DC power. The induced voltage due to flux modulation effect can be used to offer AC power, and the induced voltage due to the outer rotor can be used to offer DC power. The voltage frequency of two sets windings is different. The last one is the air gap flux rotation speed amplification due to flux modulation effect. Time stepping finite element method is used to analyse the dynamic performance of the proposed machine.
Coordinated control of rotor kinetic energy and pitch angle for large‐scale doubly fed induction generators participating in system primary frequency regulation
Authors: Yang Peihong , He Bin , Wang Biao , Dong Xiaoling , Liu WenYing , Zhang Jihong , Wu ZhenKui , Liu Jing‐Xia , Qin Zhigang
Published: March 2021

This paper presents a control strategy of large‐scale wind‐thermal power joint primary frequency regulation. First, an integrated control strategy is established rotor kinetic energy control and pitch angle control for wind turbine generators participation in frequency regulation within a wide range of wind velocity; Second, a fuzzy PI controller is designed for the recovery control of the wind turbine, which can avoid the occurrence of the frequency secondary drop accident during the wind generator exits the frequency regulation. Third, an optimal allocation power strategy of wind generator frequency modulation based on weighting factors is proposed in different operating conditions to make full use of the frequency modulation capability of wind turbine rotor kinetic energy control, and the strategy of orderly exiting the frequency modulation of the wind generators is established. Finally, the control framework for proposing the strategy is constructed to enhance the primary frequency regulation ability of large‐scale wind generators connected to power systems. The feasibility of proposing the strategy is verified by two examples. The results show that the presented strategy is able to heighten the characteristics of the power system frequency response availably and provide a reference for power system scheduling with large‐scale wind power.
A co‐occurrence matrix‐based matching area selection algorithm for underwater gravity‐aided inertial navigation
Authors: Wang Chenglong , Wang Bo , Deng Zhihong , Fu Mengyin
Published: March 2021

The matching area selection algorithm is one of the key technologies for underwater gravity‐aided inertial navigation system, which directly affects the positioning accuracy and matching rate of underwater navigation. The traditional matching area selection algorithms usually use the statistical characteristic parameters of gravity field. However, the traditional algorithms are difficult to reflect the spatial relation characteristic of gravity field, which always miss some latent matching areas with obvious change of gravity field. In order to solve this problem, the matching area selection algorithm based on co‐occurrence matrix is proposed. The proposed algorithm establishes gravity anomaly co‐occurrence matrix and extracts spatial relation characteristic parameters to reflect the gravity field. The comprehensive spatial characteristic parameter is built by entropy and is used to select the matching area by maximization of inter‐class variance. The experimental results show that the proposed algorithm can select more effective matching areas than the traditional algorithms.
Numerical analysis of the Volterra differential equations via a combination of evolutionary algorithms with moving least squares and finite difference methods
Authors: Mahmoodabadi Mohammad Javad
Published: March 2021

In this paper, the Volterra differential equations governing on the predator‐prey dynamics is numerically solved through the combination of evolutionary algorithms with Moving Least Squares as well as the Finite Difference Method. Among the numerous evolutionary algorithms, the Genetic Algorithms and Particle Swarm Optimization, as two powerful and effective approaches, are selected. The penalty method is chosen to impose the initial conditions on the objective function, while the Moving Least Squares is implemented to interpolate the derivatives in the differential equations. In order to illustrate the effectiveness of the Moving Least Squares, the results are compared with those obtained via the Finite Difference Method based evolutionary algorithms. Moreover, the results are associated with those of a numerical method and an analytical scheme to evaluate the obtained populations of the prey and the predator. These comparisons clearly illustrate the reliability and efficiency of the proposed methodology to solve nonlinear differential equations.
A SOPHIE RV search for giant planets around young nearby stars (YNS)
Authors: Grandjean A. , Lagrange A.-M. , Meunier N. , Rubini P. , Desidera S. , Galland F. , Borgniet S. , Zicher N. , Messina S. , Chauvin G. , Sterzik M. , Pantoja B.
Published: March 2021

Context.The search of close (a≲ 5 au) giant planet (GP) companions with radial velocity (RV) around young stars and the estimate of their occurrence rates is important to constrain the migration timescales. Furthermore, this search will allow the giant planet occurrence rates to be computed at all separations via the combination with direct imaging techniques. The RV search around young stars is a challenge as they are generally faster rotators than older stars of similar spectral types and they exhibit signatures of magnetic activity (spots) or pulsation in their RV time series. Specific analyses are necessary to characterize, and possibly correct for, this activity.

Aims.Our aim is to search for planets around young nearby stars and to estimate the GP occurrence rates for periods up to 1000 days.

Methods.We used the SOPHIEspectrograph on the 1.93 m telescope at the Haute-Provence Observatory to observe 63 A−Myoung (<400 Myr) stars. We used our Spectroscopic data via Analysis of the Fourier Interspectrum Radial velocities software to compute the RVs and other spectroscopic observables. We then combined this survey with the HARPSYNS survey to compute the companion occurrence rates on a total of 120 youngA−Mstars.

Results.We report one new trend compatible with a planetary companion on HD 109647. We also report HD 105693 and HD 112097 as binaries, and we confirm the binarity of HD 2454, HD 13531, HD 17250 A, HD 28945, HD 39587, HD 131156, HD 142229, HD 186704 A, and HD 195943. We constrained for the first time the orbital parameters of HD 195943 B. We refute the HD 13507 single brown dwarf (BD) companion solution and propose a double BD companion solution. Two GPs were previously reported from this survey in the HD 113337 system. Based on our sample of 120 young stars, we obtain a GP occurrence rate of 1−0.3+2.2% for periods lower than 1000 days, and we obtain an upper limit on BD occurrence rate of 0.9−0.9+2% in the same period range. We report a possible lack of close (P∈ [1;1000] days) GPs around young FK stars compared to their older counterparts, with a confidence level of 90%.
Modeling chemistry during star formation: water deuteration in dynamic star-forming regions
Authors: Jensen S. S. , Jørgensen J. K. , Furuya K. , Haugbølle T. , Aikawa Y.
Published: March 2021

Context. Recent observations of the HDO/H2O ratio toward protostars in isolated and clustered environments show an apparent dichotomy, where isolated sources show higher D/H ratios than clustered counterparts. Establishing which physical and chemical processes create this differentiation can provide new insights into the chemical evolution of water during star formation and the chemical diversity during the star formation process and in young planetary systems.

Aims. We seek to determine to what degree the local cloud environment influences the D/H ratio of water in the hot corinos toward low-mass protostars and establish which physical and chemical conditions can reproduce the observed HDO/H2O and D2O/HDO ratios in hot corinos.

Methods. The evolution of water during star formation is modeled using 3D physicochemical models of a dynamic star-forming environment. The physical evolution during the protostellar collapse is described by tracer particles from a 3D MHD simulation of a molecular cloud region. Each particle trajectory is post-processed using RADMC-3D to calculate the temperature and radiation field. The chemical evolution is simulated using a three-phase grain-surface chemistry model and the results are compared with interferometric observations of H2O, HDO, and D2O in hot corinos toward low-mass protostars.

Results. The physicochemical model reproduces the observed HDO/H2O and D2O/HDO ratios in hot corinos, but shows no correlation with cloud environment when similar initial conditions are tested. The observed dichotomy in water D/H ratios requires variation in the initial conditions, for example the duration and temperature of the prestellar phase. Reproducing the observed D/H ratios in hot corinos requires a prestellar phase duration t ~ 1−3 Myr and temperatures in the range T ~ 10−20 K prior to collapse. Furthermore, high cosmic-ray ionization rates (ξH2 ~ 10−15 s−1) appear to be incompatible with the observed D/H ratios toward low-mass protostars.

Conclusions. This work demonstrates that the observed differentiation between clustered and isolated protostars stems from differences in the molecular cloud or prestellar core conditions and does not arise during the protostellar collapse itself. The observed D/H ratios for water in hot corinos are consistent with chemical inheritance of water, and no resetting during the protostellar collapse, providing a direct link between the prestellar chemistry and the hot corino.
Identification of alkylsalicylic acids in Lentisk oil (Pistacia lentiscus L.) and viability assay on Human Normal Dermal Fibroblasts
Authors: Benalia Nabiha , Boumechhour Abdenour , Ortiz Sergio , Echague Cristian A. , Rose Thorsten , Fiebich Bernd L. , Chemat Smain , Michel Sylvie , Deguin Brigitte , Dahamna Saliha , Boutefnouchet Sabrina
Published: March 2021

Pistacia lentiscus L. (Anacardiaceae) is widely distributed in the Mediterranean basin. Its fruit oil is used in traditional medicine to treat burns, skin impairments as well as inflammatory diseases as soothing massage or internal use. An increased interest is spotted lately with several commercial brands are spun portraying the benefits of this oil but with no stringent regulations to ascertain its safe use as an edible or cosmeceutical product. This work concerned the investigation of secondary metabolites presents in Pistacia lentiscus fruits oil using both GC-MS and HPLC-DAD-MS technics, and the evaluation of cytotoxicity on human normal dermal fibroblasts to assess safety of use as cosmetic ingredient. This study stands as the first one to report the identification of alkylsalicylic acids in fruits oil and unsaponifiable fraction of Pistacia lentiscus fruit oil which calls for therefore, quantification of alkylsalicylic acids, known as skin irritants, in Pistacia lentiscus oil, used as nutraceuticals or cosmeceuticals by manufacturers.
Open approaches for cruciate ligament reconstruction in knee dislocations: A technical note and case series
Authors: Held Michael , Laubscher Martiz , von Bormann Richard , Richter Dustin L. , Wascher Daniel C. , Schenck Robert C.
Published: March 2021

Introduction: Arthroscopic surgery is the gold standard for cruciate ligament reconstruction in multi-ligament knee injuries. However, hospitals in limited-resource settings often lack arthroscopic-trained surgeons or equipment. Open approaches for treating knee dislocations can overcome many of these limitations.Methodology: This study aims to describe techniques for open approaches in a supine patient to address the cruciate ligaments in multi-ligament knee injuries and to review associated complications and clinical outcomes in a retrospective case series.Results: Ten patients with multi-ligament knee injuries who had undergone open cruciate ligament reconstruction between July 2016 and November 2018 were retrospectively identified. Open approaches were performed owing to the extravasation of arthroscopy fluid into the posterior compartment (3) or a large traumatic arthrotomy (7). Complications and patient-reported outcomes were analysed. Eight of the 10 patients were followed up at 10 months postoperatively (range, 5–23 months). None had iatrogenic neurovascular damage. Median outcomes scores were: visual analogue scale, 45 (range, 0–100); Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form, 81.4 (range, 75–100); Lysholm, 85 (range, 67–92).Discussion: Open approaches were safe and useful in treating cruciate ligaments and should be considered in arthroscopy fluid extraversion and large traumatic arthrotomies.
Auswirkungen geburtshilflicher Analgesie mit systemischen Opioiden auf das Neugeborene – eine Übersichtsarbeit
Authors: Seiler Berenike , Deindl Philipp , Somville Thierry , Ebenebe Chinedu Ulrich , Hecher Kurt , Singer Dominique
Published: March 2021

Einleitung Dreiviertel aller Gebärenden erhalten während der Geburt eine Analgesie. Es stehen regionale und systemische Analgesieverfahren zur Verfügung. Diese Übersichtsarbeit analysiert die Datenlage zu den Auswirkungen einer geburtshilflichen Analgesie mit systemischen Opioiden auf das Neugeborene.

Methoden Die Datenbanken PubMed und Cochrane Library wurden nach den folgenden Begriffen durchsucht: „Meptazinol“, „Meptid“, „analgesia“, „painkiller“, „pain reliever“, „obstetrics“, „labor“, „labour“, „delivery“, „neonate“, „newborn“, „child“, „baby“, „infant“, „fetus“, „fetal“, „opioid“ und „opiate“ sowie zusätzlich eine MeSH Terms Suche in PubMed durchgeführt.

Ergebnisse Von 355 potenziell relevanten Studien wurden 23 Studien in diese Arbeit eingeschlossen. Die Studien variierten stark in Qualität, Stichprobengröße und Outcome-Kriterien. Das neonatale Outcome war häufig nur ein sekundärer Endpunkt. Selten wurden signifikante Unterschiede bezogen auf das Outcome der Neugeborenen zwischen den verschiedenen systemischen Opioiden oder im Vergleich zu Kontrollgruppen berichtet. In 12 Studien wurden die APGAR-Werte der Neugeborenen zwischen Behandlungsgruppen verglichen, wobei sich bei 10 (83%) dieser Studien keine Unterschiede zeigten.

Diskussion/Ausblick Die Evidenzlage zu Auswirkungen geburtshilflicher Analgesie mit systemischen Opioiden ist insgesamt gering und Studien zum Langzeit-Outcome von Neugeborenen fehlen. Auch die Frage, ob eine postnatale Überwachung der Neugeborenen notwendig ist, kann nicht klar beantwortet werden. Studien mit prospektivem Studiendesign sollten durchgeführt werden.
„Pro und contra Milzpunktion“ oder besser „wann und wann nicht?“
Authors: Safai Zadeh Ehsan , Dietrich Christoph F. , Görg Christian , Bleyl Tobias , Alhyari Amjad , Ignee Andre , Jenssen Christian , Trenker Corinna
Published: March 2021

Aufgrund der relativ hohen Komplikationsrate wird die Notwendigkeit einer Milzbiopsie kontrovers diskutiert. Bei der Indikationsstellung sind der klinische Hintergrund und die bereits erfolgte Diagnostik zu berücksichtigen. Anhand der Anamnese, der bildgebenden Verfahren und des sonografischen Verlaufs sind unterschiedliche klinische Szenarien vorstellbar. Das Ziel der Arbeit ist es, die Indikation einer Milzbiopsie unter Beachtung unterschiedlicher klinischer Szenarien zu beschreiben.