bluuebunny/crossref_metadata_2025 huggingface dataset:
Caries Risk Documentation And Prevention: eMeasures For Dental Electronic Health Records
Authors: Bangar Suhasini , Neumann Ana , White Joel M. , Yansane Alfa , Johnson Todd R. , Olson Gregory W. , Kumar Shwetha V. , Kookal Krishna K. , Kim Aram , Obadan-Udoh Enihomo , Mertz Elizabeth , Simmons Kristen , Mullins Joanna , Brandon Ryan , Walji Muhammad F. , Kalenderian Elsbeth
Published: January 2022

Background Longitudinal patient level data available in the electronic health record (EHR) allows for the development, implementation, and validations of dental quality measures (eMeasures).

Objective We report the feasibility and validity of implementing two eMeasures. The eMeasures determined the proportion of patients receiving a caries risk assessment (eCRA) and corresponding appropriate risk-based preventative treatments for patients at elevated risk of caries (appropriateness of care [eAoC]) in two academic institutions and one accountable care organization, in the 2019 reporting year.

Methods Both eMeasures define the numerator and denominator beginning at the patient level, populations' specifications, and validated the automated queries. For eCRA, patients who completed a comprehensive or periodic oral evaluation formed the denominator, and patients of any age who received a CRA formed the numerator. The eAoC evaluated the proportion of patients at elevated caries risk who received the corresponding appropriate risk-based preventative treatments.

Results EHR automated queries identified in three sites 269,536 patients who met the inclusion criteria for receiving a CRA. The overall proportion of patients who received a CRA was 94.4% (eCRA). In eAoC, patients at elevated caries risk levels (moderate, high, or extreme) received fluoride preventive treatment ranging from 56 to 93.8%. For patients at high and extreme risk, antimicrobials were prescribed more frequently site 3 (80.6%) than sites 2 (16.7%) and 1 (2.9%).

Conclusion Patient-level data available in the EHRs can be used to implement process-of-care dental eCRA and AoC, eAoC measures identify gaps in clinical practice. EHR-based measures can be useful in improving delivery of evidence-based preventative treatments to reduce risk, prevent tooth decay, and improve oral health.
Blueprints offer replicable method to measure capillary liquid bridges
Authors: Patrick Chris
Published: January 2022

A setup characterizes both force and geometry associated with capillary bridges between liquid infused surfaces at lower cost than existing rigs.
Construction of Nahm data and BPS monopoles with continuous symmetries
Authors: Charbonneau Benoit , Dayaprema Anuk , Lang C. J. , Nagy Ákos , Yu Haoyang
Published: January 2022

We study solutions to Nahm’s equations with continuous symmetries, and under certain (mild) hypotheses, we classify the corresponding Ansätze. Using our classification, we construct novel Nahm data and prescribe methods for generating further solutions. Finally, we use these results to construct new BPS monopoles with spherical symmetry.
Synchronization in cilia carpets and the Kuramoto model with local coupling: Breakup of global synchronization in the presence of noise
Authors: Solovev Anton , Friedrich Benjamin M.
Published: January 2022

Carpets of beating cilia represent a paradigmatic example of self-organized synchronization of noisy biological oscillators, characterized by traveling waves of cilia phase. We present a multi-scale model of a cilia carpet that comprises realistic hydrodynamic interactions between cilia computed for a chiral cilia beat pattern from unicellular Paramecium and active noise of the cilia beat. We demonstrate an abrupt loss of global synchronization beyond a characteristic noise strength. We characterize stochastic transitions between synchronized and disordered dynamics, which generalize the notion of phase slips in pairs of coupled noisy phase oscillators. Our theoretical work establishes a link between the two-dimensional Kuramoto model of phase oscillators with mirror-symmetric oscillator coupling and detailed models of biological oscillators with asymmetric, chiral interactions.
Analysis on numerical stability and convergence of Reynolds averaged Navier–Stokes simulations from the perspective of coupling modes
Authors: Liu Yilang , Cao Wenbo , Zhang Weiwei , Xia Zhenhua
Published: January 2022

Reynolds-averaged Navier–Stokes (RANS) simulations are still the main method to study complex flows in engineering. However, traditional turbulence models cannot accurately predict flow fields with separations. In such a situation, machine learning methods provide an effective way to build new data-driven turbulence closure models. Nevertheless, a bottleneck that the data-driven turbulence models encounter is how to ensure the stability and convergence of the RANS equations in a posterior iteration. This paper studies the effects of different coupling modes on the convergence and stability between the RANS equations and turbulence models. Numerical results demonstrate that the frozen coupling mode, commonly used in machine learning turbulence models, may lead to divergence and instability in a posterior iteration; while the mutual coupling mode can maintain good convergence and stability. This research can provide a new perspective to the coupling mode for machine learning turbulence models with RANS equations in a posterior iteration.
Supersonic turbulent channel flows over spanwise-oriented grooves
Authors: Yuan XianXu , Fu YaLu , Chen JianQiang , Yu Ming , Liu PengXin
Published: January 2022

In the present study, we perform direct numerical simulations to study the influences of the spanwise-oriented grooves, which are emulated by the reasonably designed “relaxed” boundary conditions, on the kinetic and thermodynamic statistics in a supersonic turbulent channel flow at the Mach number of 1.5 and Reynolds number of 3000. The phase averaged flow fields show that the relaxed boundary induces compressive and expansive waves that travel across the whole channel and are reflected by the upper wall. These waves are isentropic in the average sense except in the viscous sublayer. In the near-wall region, vortices and streaks that constitute the self-sustaining cycles are less populated and less meandering, while in the outer region, especially near the channel center, the velocity divergence is as strong as the vorticity. The temperature, density, and pressure fluctuations are enhanced by these waves. The correlations between the velocity and temperature are altered, due to the counter effects caused by the vortical motions and isentropic waves.
Research on the feasibility and mechanism of the intermittent flash evaporation
Authors: Ni Peiwei , Wen Zhi , Su Fuyong
Published: January 2022

An intermittent flash evaporation method is proposed. The experimental system of the flashing is realized by an intake or extraction system composed of two solenoid valves and a controller. The feasibility of this flashing method is verified through experiments under conditions of different time ratios of intake to extraction. The mechanism of the intermittent flashing method was studied by analyses of liquid temperature, pressure gradient in the flash chamber, and pressure difference between the flash chamber and the vacuum chamber in flashing processes under different conditions. Results suggested that the amount of steam produced by the flash evaporation with the increase in liquid superheat was more than that of the process with a certain superheat. Periods of intake and the extraction of the intermittent flash evaporation influenced the flashing efficiency significantly. By comparing the results with continuous static flashing, the intermittent flash evaporation is proven capable of improving the flashing efficiency. Appropriate intake and extraction periods promote the flashing process and reduce the amount of air intake in a single flashing cycle.
Phosphorus constraints to potential land area cropped under organic and regenerative systems in Australia
Authors: Rose Terry J. , Thompson-Brewster Emma , Cornish Peter S.
Published: January 2022

Context The removal of phosphorus (P) in harvested grain and poor recycling of P creates unique concerns for farming systems that aim to reduce reliance on non-renewable fertiliser inputs, such as ‘regenerative’ farming systems, or for organic grain growers for whom synthetic P inputs are prohibited. Aims and methods We examine gross P budgets across the Australian cropping landscape and explore implications for the land area that could be potentially cropped if all P removed in harvested produce was replaced using domestic recycled P sources. Key results Major cereal, pulse and oilseed crops occupied 21.7 million ha year−1 on average from 2000 to 2018, removing around 136 274 t P year−1. The 27 200 t P in captured animal manure could only sustain around 20% of this area. A further 23%, around 4.9 million ha, could be sustained from sewage and greenwaste resources, but potential pathogens/contaminants limit their current use on organic farmland, and on other farmland when contaminant levels exceed thresholds. Conclusions Development of technologies acceptable to organic certifying agencies to extract P from sewage and greenwaste would expand available resources for organic and regenerative farming and would enable systems to move further towards closed loop nutrient cycling. Ultimately, export of grain overseas results in a large deficit between the 136 000 t P removed annually from fields and domestic recyclable P (around 74 000 t P year−1). Implications Apart from importing rock phosphate-based P or recycled P products, this deficit could only be overcome in the long term by reducing grain exports, or by reducing the concentration of P in exported grain.
The phonetic tone change *high > rising
Authors: Yang Cathryn
Published: January 2022

Previous research has proposed a direct path from consonantal effects on F0 to the development of a rising tone value. However, findings from tone change studies in Asian languages suggest an additional pathway to rising: a high tone (i.e., with a tonal target in the upper pitch range) may evolve into a rising tone. This study examines tone change pathways to rising in the Ngwi (Loloish) languages. Among the 11 Ngwi language clusters examined, a new rising tone value has unambiguously developed from an historically high tone in nine of them. In several clusters, prevocalic consonants conditioned a tone split, but in other clusters, *high > rising appears after both voiced and voiceless prevocalic consonants. The findings suggest that a high tonal target is a suprasegmental condition favorable to the development of a rising tone value, as reaching a high tonal target in connected speech frequently entails a rising contour.
Refractive index sensing of twin-core fiber based on Mach Zehnder interference and SPR effect
Authors: Meng Xiaojian , Li Shuguang , Li Jianshe , Guo Ying , Han Ying , Wang Yan , Gong Lin , Yuan Jinhui , Qiu Shi , Shen Jing
Published: January 2022

The sensing characteristics of twin-core fiber for refractive index (RI) detection are presented and experimentally investigated. In this work, for the first time, we demonstrate the manufacturing method of optical fiber sensor based on Mach Zehnder interference and surface plasmon resonance. Mode interference and resonance coupling effect are thoroughly realized with the misalignment fusion and silver mirror reaction. It is found that the sensitivity of the proposed sensor is 3020 nm RIU−1 in the RI ranging from 1.3333 to 1.3804, which is much higher than that of the conventional fiber sensor. Moreover, experimental data indicate that this sensor has the advantages of easy fabrication, good repeatability and good stability. According to these characteristics, we introduce one specific application of pregnancy detection to validate the application of the designed sensor in biomedical field.
Seed-assembly-mediated fabrication and application of highly branched gold nanoshells having hollow and porous morphologies
Authors: Park Tae-Hyeon , Jeong Dong-Won , Lee Jung Ho , Jang Du-Jeon
Published: January 2022

Highly branched gold nanoshells (BAuNSs) having hollow and porous morphologies have been fabricated via a seed-assembly-mediated strategy. Gold seed assemblies can be prepared by removal of SiO2 nanotemplates with help of polyvinylpyrrolidone (PVP) molecules, which weakly link gold nanoparticles together even after SiO2 etching. L-3,4-dihydroxy phenylalanine (L-DOPA) and AgNO3 are employed as shape-directing agents to induce the anisotropic growth of gold. BAuNSs exhibit 7.4 and 4.4 times stronger activities than SiO2@Au nanoparticles in catalysis and surface-enhanced Raman scattering (SERS) applications, respectively, due to their large surface areas and numerous hot spots. It is necessary to find the optimal amount of gold deposition in fabrication to effectively utilize the hollow and porous morpologies of BAuNSs for catalysis and SERS applications. Overgrown nanobranches can fill the nanopores and nanogaps of BAuNSs, resulting in decrease of activities in applications. Overall, the seed-assembly-mediated fabrciation can be employed to produce plasmonic nanostructures having unique morphologies and high application activities.
Electronic, optical, and catalytic properties of finite antimonene nanoribbons: first principles study
Authors: Osman Waleed , Saad Mohamed , Ibrahim Medhat , Yahia Ibrahim , Abdelsalam Hazem , Zhang Qinfang
Published: January 2022

Finite antimonene nanoribbons are investigated using density functional theory calculations. Attaching chemical groups, like COOH and OH, to the edges has been successfully attained with negligible deformation and moderate binding energy. They are semiconductors with energy gap ∼2.3 eV that slightly affected by attaching groups such as C2H5 or significantly decreases to 1.8 eV by attaching NO. The optical gaps, from 1.5 eV to 2 eV, are lower than the electronic ones which indicate the existence of excitonic transitions that appear due to the quantum confinement in the finite nanoribbons. Oxygen evolution on the edges shows better catalytic activity than on the surface due to the moderate adsorption of reaction intermediates in the former. Thus, the nanoribbons are preferable for water oxidation than the bulk antimonene. Attaching chemical groups slightly worsen the process due to the stronger adsorption of reaction intermediates. A minimum overpotential of 0.38 V has been achieved in unmodified zigzag-nanoribbons. This value in addition to the appropriate energy gap make antimonene nanoribbons excellent photocatalysts for water splitting.
The entanglement and second-order coherence function in a two-atom nonlinear Jaynes-Cummings model
Authors: Mo Chuan , Xu Kai , Zhang Guo-Feng
Published: January 2022

The influence of the Kerr nonlinearity on the two two-level atoms entanglement is investigated in Jaynes–Cummings model (JCM), so that one of atoms is inside the cavity field and the other atom is outside it. We show that the entanglement of atoms increases with the decrease of the phase decoherence rate or Kerr coefficient, when considering the effect of external environment. Then due to the statistic properties of the anti-bunching effect of photons are related to entanglement, the nonlinear JCM is examined theoretically to analyze the bunching or anti-bunching effect by using the second-order coherence function. We find that the second-order coherence function decreases with the Kerr coefficient. Our results show that the field reflects the stronger bunching effect with the bigger average photon number.
Resonances ρ(1450)+ and ρ(1700)+ in B → DKKdecays *
Authors: Ma Ai-Jun , Wang Wen-Fei
Published: January 2022

The contributions for the kaon pair from the intermediate states

and

in the decays

,

, and

are analyzed within the perturbative QCD factorization approach. The decay amplitudes for all concerned decays in this work are dominated by the factorizable Feynman diagrams with the emission of the kaon pair, and the charged ρ mesons should be of great importance in the

channel of the related three-body B decays. Moreover, these quasi-two-body decays are CKM-favored, and the relevant branching ratios are predicted to be in the order of

, which have the potential to be measured by experiments. It is also shown that the contributions of the subprocesses

for the three-body B meson decays are considerable according to the total three-body branching fractions presented by Belle. Therefore, the decays

,

, and

can be employed to study the properties of

and

in the LHCb and Belle-II experiments.
Influence of Megaregolith on the Thermal Evolution of Mercury’s Silicate Shell
Authors: Xie Jing-Chun , Zhang Mian , Huang Cheng-Li
Published: January 2022

A so-called megaregolith layer that is considered to be produced by continuous impacts in Mercury’s early stages is integrated into the thermal evolution models of Mercury to study its influence on the thermal evolution of Mercury’s silicate shell. This research first implements a one-dimensional parametric global thermal evolution model. Our results indicate that megaregolith directly affects the thermal evolution of Mercury’s silicate shell by virtue of its good insulation performance. The way megaregolith exerts its influence is by prolonging the process of partial melting and reducing the heat loss, resulting in a thicker crust and thinner stagnant lid. As for the deep parts of the silicate shell, it is suggested that more energy is taken away from the mantle due to the longer partial melting, leading to lower temperatures below the crust compared with the case in the absence of megaregolith, which further helps to advance the formation time of the inner core and promote its final size. In addition, we also carry out a simplified two-dimensional mantle convection simulation as a supplement to the one-dimensional model. The two-dimensional simulation depicts a typical mantle plume fractional melting scenario. Our calculations indicate that megaregolith may be key to the long-term volcanic activities on Mercury. As far as the megaregolith itself is concerned, the thermal structure of this particular layer is more sensitive to thermal conductivity, suggesting that for such a highly fragmented structure, the thermal conductivity coefficient plays a key role in its evolution. Our work emphasizes the importance of megaregolith to the evolution of Mercury.
Artificial intelligence-based condition monitoring and predictive maintenance framework for wind turbines
Authors: Maron Janine , Anagnostos Dimitrios , Brodbeck Bernhard , Meyer Angela
Published: January 2022

The global wind power capacity continues to grow at a fast pace. However, the profit margins from wind power are being compressed in many countries. Thus, many wind farm owners seek to reduce their operational expenses, including those for maintenance work. In this study, an artificial intelligence-based condition monitoring and predictive maintenance framework for wind turbines is presented. The purpose of this framework is the automated early detection of operational faults in wind turbine systems and subsystems. The early detection of anomalies enables further diagnosis, condition-based maintenance and better planning of repairs. It can prevent consequential damage, lead to fewer turbine downtimes and extend the service lives of the monitored turbines. We present validation results from two onshore wind farms and demonstrate 97% accuracy for a 2-month detection horizon of developing fault events that require attention from maintenance staff.
How do NEWA and ERA5 compare for assessing offshore wind resources and wind farm siting conditions?
Authors: Meyer P J , Gottschall J
Published: January 2022

In advance to the construction of a wind farm, a wind resource assessment is performed, often by the use of wind atlas data. Two widely used and publicly available numerical datasets, ERA5 and the recently created NEWA, are compared and evaluated regarding wind climatology, variability and extreme wind speeds using a comprehensive database with high quality offshore measurements. NEWA shows to be more accurate but less precise in terms of predicting mean wind speed and correlation coefficients. However, the higher temporal resolution of NEWA causes a better representation of the wind variability for the offshore sites. Extreme wind speed predictions based on both numerical datasets are underestimated on average. The spectral correction method is applied and found to be appropriate for the correction of the error in predicting the 50-year return wind speed from the numerical datasets for some sites while it fails for others.
Innovative meshless approach for shaped charges applications
Authors: Collé Anthony , Limido Jérôme , Unfer Thomas , Vila Jean-Paul
Published: January 2022

We focus here on modelling shaped charges. Combining large deformations, numerous interfaceproductions, and strong damage mechanisms, those events are particularly challenging from a numerical point of view. Eulerian finite element methods are classically used for such modeling.However, they induce very long computation times, accuracy losses (projection algorithms), anddifficulties with opening criteria related to jet fragmentation. Among the Lagrangian approaches, the meshless method called Smoothed Particle Hydrodynamics (SPH) appears as a relevant alternative to prevent such shortcomings. Based on a set of moving interpolation points, it disregards any connectivity between its elements which makes it naturally well suited to handle material failure. Nevertheless, SPH schemes suffer from well-known instabilities questioning their accuracy and activating nonphysical processes,such as numerical fragmentation. Many stabilizing tools are available in the literature however, they either raise conservation and consistency issues or drastically increase the computation times. We propose then to use an alternative scheme called γ-SPH-ALE. Based on the ALE framework, it achieves robust and consistent stabilization through an arbitrary description of motion. Thanks to CFL-like conditions obtained through a nonlinear stability analysis, the scheme stability is ensured. By preventing spurious oscillations in elastic waves and correcting the so-called tensile instability, both stability and accuracy are increased regarding classical approaches. Also, taking advantage of GPU computing, such results are achieved in reduced computation times contrary to classical CPUimplementations. Its implementation on a “Viper” shaped charge shows that the scheme handles the jet generation process as well as its resulting interaction with a target.
Choosing the thermal conduction equation solution method in SPH
Authors: Rykovanov Vasiliy S , Sapozhnikov Filipp A
Published: January 2022

The set of explicit iterative schemes for parabolic problems (heat conduction as example) is reviewed. The iterative process is constructed based on algebraic polynomials (Chebyshev, Lanczos, or Legendre) properties. They combine the simplicity of explicit time-integration with the increased allowed timestep. This approach may be applied at smoothed particle hydrodynamics (SPH) simulations as a replacement for the popular implicit time-integration schemes, whose drawbacks might get stronger especially on SPH-like contrary to mesh-style space description.
Numerical simulation of solid-phase chemical transformations in thermite mixtures under shock-wave loading
Authors: Ivanova O V , Cherepanov R O , Zelepugin S A
Published: January 2022

Shock-wave loading of a steel cylindrical ampoule that contained an aluminum-copper oxide(Al/CuO) thermite mixture is simulated in three-dimensional space using the SPH method.The chemical reaction starts after the performance of the criterion on temperature or pressure.Thechemical reaction equations are integrated using the first-order Euler method.The elastic-plastic flow is calculated using the variational formulation.The numerical study of solid-phase chemical transformations in the Al/CuO thermite mixture under shock-wave loading shows that the initiation of reactions in the shock wave,further development,and completion depends significantly on the amplitude and duration of the shock wave.Sub-critical pressure pulse can lead to an incomplete reaction or incompletely compacted final product.
Chemical kinetics in a five-component air behind shock waves
Authors: Karpenko A G , Tolstoguzov S S , Volkov K N
Published: January 2022

The inuence of non-equilibrium kinetic processes on macroscopic parameters in air flows is a challenging and an important problem. Particularly, simulation of flows with high-temperature effects is important near the surface of spacecraft or meteorites when they enter the Earth’s atmosphere. Non-equilibrium flows of a reacting five-component air mixture consisting of N2, O2, NO, N, O behind a shock wave at different altitudes in the Earth’s atmosphere and different speeds of the inlet flow are investigated. The lengths of the relaxation zones are considered to evaluate the applicability of one-temperature thermodynamics model for calculating the macroscopic fluid quantities behind the shock wave. The results of the flow simulation are obtained with in-house code developed for super-and hypersonic applications. The results from the code are compared with the results of numerical calculations computed with the equilibrium thermodynamics model
Performance Comparison and Optimization Scheme of 35 kV Medium Voltage Power Cable Pipe Laying
Authors: Han Xiao , Liu Xiongjun , Di Hongjie , Jiang Yunpeng , Ni Sien
Published: January 2022

Based on the image method and superposition method, the calculation model of ampacity of 35kV Cable laid in power pipe is established. According to the model, the ampacity of 8-Circuit cable in different arrangement forms of power pipe is calculated, and the variation of ampacity under 6×4 arrangement, 4×6 arrangement, 3×8 arrangement and 2×12 arrangement is analyzed, thus the recommended arrangement form of power pipe based on ampacity maximization is proposed.
System Verification Scheme Based on an MCU
Authors: Liu Yulin , Huang Sufang , Wang Haining , Hou Yueliang , He Xianzhuan , Zhu Xinwei , Li Ting , Liu Xiaolu
Published: January 2022

In order to systematically verify the common functions of each peripheral of the chip, find out the problems in the process of chip design in time, and avoid mutual interference between the peripherals of the chip, it is very necessary to systematically verify the chip. The MCU involved in this verification scheme has three cores and several peripherals such as UART, SPI, USB, GMAC and DCMI. In this paper, the common functions of the peripherals of the MCU are verified systematically, and the verification methods of each peripheral are described in detail. The software of this scheme is layered and modular, and the verification system realized according to this scheme can be conveniently transplanted to different chips.
Visual Navigation Method for Carrier-based Aircraft Landing
Authors: Han Hao
Published: January 2022

Carrier landing of fixed-wing aircraft is the most difficult and challenging task in the aerial field. Precise and reliable landing systems are the key to carrier landing. Visual navigation has the advantages of high precision of the relative navigation. Hence, it has become a promising method for landing systems. However, tracking the targets continuously and extracting the coordinates of the targets accurately are challenges for visual navigation due to the complex environment and dramatic distance changes during carrier landing. Therefore, a visual navigation method utilizing an airborne medium-wave infrared camera to track four infrared targets installed on the carrier, which can operate in low visibility weather conditions, is presented in this article. A segmentation detection method was adopted for tracking the targets. The kernel correlation filter was used to detect the targets when the aircraft was far from the carrier stern, which could quickly track targets with relatively constant dimensions. A convolutional neural network classifier based on transfer learning was used to detect the targets when nearing the carrier, thereby reducing the risk of losing targets due to severe dimensional changes. Finally, the relative position and attitude information could be obtained by the POSIT (pose from orthography and scaling with iterations) pose estimation algorithm. On-vehicle experiments were performed, and the results verified the effectiveness of the method.
Research on Load Characteristic Data Clustering Based on Transfer Learning
Authors: Xu Wei , Wang Zhenshu , Sun Jingyu , Zhong Xun
Published: January 2022

As power system informatization developed, the distribution network side has accumulated a lot of load data. As an effective data processing method, cluster analysis is helpful to mine the valuable information hidden in the load data and extract accurate load characteristics. In order to extract intuitive and effective load characteristics, a load characteristic data clustering method based on transfer learning is proposed, which deeply studies the problem of ignoring the data distribution difference between training set and testing set in the traditional clustering process. Case studies verify the efficiency and effectiveness of the algorithm.
Design and Simulation of Selective Short Circuit Protection System in AC Microgrid with Grid-connected Mode
Authors: Chen Bingbing , Liu Guofeng , Chen Jiankun , Mao Zhen , Ju Cheng , Chen Yong
Published: January 2022

The fast detection and accurate location on short-circuit faults has always been the research direction of AC microgrid fault protection. A short-circuit fault protection system for grid-connected AC microgrid is designed based on dsPIC33FJ32GP204 in this paper, which realizes the fast detection and regional location. The short-circuit fault simulation model is built on PSCAD, and all kinds of fault waveforms generated by simulation are imported into Proteus. The designed protection system is used to transform the wavelet energy spectrum of all kinds of fault waveforms generated by simulation, and then output the corresponding control signal to circuit breakers. Simulation results show that the control system can quickly perceive and accurately locate the microgrid short-circuit fault area and realize the output of selective protection signal.
Design and Application of Single-Arm Live Working Robot System on Transmission Line
Authors: Gu Su , Hu Kang , Liu Lanlan , Li Zhihui , Chen Zhiio , Qiao Mingming , Jiang Wei
Published: January 2022

The power transmission line live working robot walks on the power transmission line through wheels. The robot arm and its end tools carried by the robot body can assist or even replace the manual implementation of live inspection and operation of the power transmission line. It has important theoretical significance and practical application value for improving work efficiency and solving dangerous problems in the operation process. In this paper, a single-arm live working robot is designed and developed for a variety of maintenance tasks on transmission lines. At the same time, a method of autonomous end reconfiguration on transmission line is proposed, so as to automatically realize transmission line inspections and live operation. The robot physical model and the motion planning of the robot manipulator arm for the typical fittings maintenance operation are given. The physical prototype system of the live working robot is developed through the system integration design. Finally, related live working experiments were carried out on the simulation test line so as to verify the feasibility and effectiveness of the single-arm live working robot realize the inspection operation of the power transmission line. The research in this article has important theoretical significance and practical application value for intelligent operation and maintenance management of transmission grids.
Optimization of Capacitor Voltage Control Strategy for MMC Sub-module
Authors: Hou Yunhai , Wang Yu
Published: January 2022

Modular Multilevel Converter (MMC) is widely studied and used because of its own advantages such as high output level number, low switching frequency and good waveform quality. The voltage equalization problem of sub-module capacitors is one of the key research directions of MMC. In the paper, a sorting method of inter-group comparison in two groups, called OF sorting method, is proposed first. The maximum time complexity of this method of sorting is N-1, but the use of this method is limited. Therefore, a new MMC hybrid sorting voltage equalization algorithm is proposed on this basis. This paper proposes a capacitor voltage equalization control strategy based on the combination of improved equalization sorting algorithm and improved insertion sorting algorithm, which reduces the computational effort by monitoring the sub-module capacitance voltage in real time, setting the dispersion index between sub-module voltages, and then controlling the opening and holding of the sorting module to reduce the number of elements to be ranked one by one. Finally, the MMC model is built in Matlab/Simulink. The simulation results show that the improved equalization control strategy can effectively reduce the computational effort and reduce the switching frequency of sub-modules on the basis of better maintaining the capacitor voltage balance.
Comprehensive Evaluation of the Transient Reactive Power Support Capability of New Energy Stations Based on TOPSIS
Authors: Chang Xiao , Zhang Min , Zhao Junyi , Yang Chaoying , Liu Yang , Fan Rui , Guo Bingwen
Published: January 2022

In order to effectively evaluate the reactive power support capability of new energy stations, an evaluation system is established with the high voltage ride through(HVRT) capability, low voltage ride through (LVRT) capability and reactive power support capability selected as the evaluation index. And then, a comprehensive evaluation method to effectively evaluate the transient reactive support capability of new energy stations is proposed in this paper. The weight of a single index was determined by the coefficient of variation method and then the comprehensive evaluation index was determined based on TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution). Finally, the rationality and effectiveness of the proposed evaluation method are verified by the measured data of a wind farm.
Study on Key Technical Schemes for Grid-connected Performance Testing of Offshore Wind Turbines
Authors: Lv Zhenhua , Li Qiang , Tang Weijia , Han Huachun , Yu Meng
Published: January 2022

Offshore has the characteristics of not occupying land, rich in wind power resources, and has the advantages of high utilization hours of power generation and suitable for large-scale development. It has become the key direction of global wind power development. It can be predicted that offshore wind energy will become a very important part of the global energy internet in the future. After 20 years of wind power operation experience and the wind power technology improvement, the business and operation environment of offshore wind power development is becoming more and more mature. As the wind turbines installation site extends from land to offshore and deep-sea areas, “large” wind turbines have become the trend of offshore wind turbines development in the future. With the large-capacity offshore wind turbine prototype of many wind turbine manufacturers in China coming off the production line and successfully put into operation in China’s coastal areas, offshore wind turbines above 6MW began to be put into commercial operation. Therefore, it is urgent to carry out relevant tests and inspections to improve the operation and grid connection performance of the unit. It is of great significance to master the operation characteristics and control methods of offshore wind turbine, qualitatively and quantitatively analyze its impact on power grid, study offshore wind power detection methods and develop relevant detection devices. Due to the differences of offshore environment, operation control and the particularity of offshore power transmission and collection mode, the onshore wind power test and detection ability can not adapt to the new changes and requirements of offshore wind energy test and detection.
Thermal Aging Analyses of a Gearbox oil Used for Wind Turbine Nacelles
Authors: Zhuang Chenhao , Zhang Yu , You Fei , Cheng Ziyan , Wang Zhengmin , Lin Guilin
Published: January 2022

The original gearbox oil (typed CALTEXMEROPA 320) used for wind turbine was heated for 96 h at 155.0 °C in air to simulate the thermal aging process. By thermogravimetry (TG) experiments in air, the thermal stability of the gearbox oil and the oil heated after 96 h were compared. The Advanced Kinetics and Technology Solutions (AKTS) tool was used to explore related thermal aging effect. The results demonstrate that the thermal decomposition processes of the gearbox oils can be divided into three stages, with major mass loss occurring in the second stage. The maximum mass loss rates are -12.0 %/min (0 h) and -13.0 %/min (96 h). The S value (combustibility index) of original gearbox oil (7.35) is higher than that of preheated oil for 96 h (6.70). The thermal aging curve of gearbox oil presents an inverted L-shape, the thermal aging rate is faster in the first week and then gradually slows down. Practically, the fire risk of gearbox oil in the initial application stage is the highest to induce a potential burning process in an unwanted high temperature (say, higher than 270.0 °C based on TG results) environment.
Simulation and Experimental Verification of Temperature Field for Square Lithium-ion Power Battery
Authors: Jin Biao , Fei Qiang , Wang Yanning , Wang Yingshun , Zou Wuyuan
Published: January 2022

Lithium-ion power battery will produce a large amount of heat during working process, which will lead to its temperature increase, and then has an important impact on the its performance and safety, enhance, in order to investigate temperature field change in the discharge process, its internal resistance experiment and temperature rise experiment under discharging rates were carried out to obtain the battery time-varying internal resistance and entropy heat coefficient. Based on heat production mechanism of lithium-ion battery, its temperature simulation under different discharging rates was carried out, and compared with the experiment. The results show that the simulation values of temperature change are in good agreement with the experiment, and the battery model can well simulate the temperature change of it, which has important guidance for the analysis of its temperature rise and the control of its thermal management process.
Technical Requirement Analysis of Regulation Characteristics of CSP Station with Heat Storage System
Authors: Fang Nengwei , Li Xiaoxue , Li Yunpeng , Li Yan , Li Yanmei , Ouyang Dejue , Tan Dong , Xin Ya
Published: January 2022

Using solar energy to generate thermal power is often called concentrating solar power (CSP), is a grid friendly clean energy utilization mode with unique development advantages. Large capacity heat storage system with relatively mature technology and low cost can be configured to ensure stable and controllable power generation. The method can be. Solar thermal power generation has become a strategic emerging industry supported by many countries around the world. Spain, the United States, India, South Africa and other countries have carried out commercial operation of power technology with solar thermal, and installed capacity is growing steadily. China has also given key support to CSP generation technology, which has been vigorously developed. As the most promising new energy technology, CSP generation from molten salt heat storage tower is one of the main technical approaches of CSP generation. The key is to store the absorbed solar heat through thermal storage materials and release it stably for a long time, so as to achieve continuous and stable power generation independent of solar radiation changes. Through analysis, this paper puts forward the key technology research and scheme of molten salt regenerative CSP generation system, promotes the research on the bidirectional relationship between CSP station and power grid, and realizes the innovation of renewable energy technology. Relevant research results and technical schemes can be popularized and applied in demonstration power stations, and can also be used for operation control of newly-built molten salt heat exchange and storage tower power stations in the future.
Experimental Study on Strength and Frost Return of Red Mud Unburned Brick
Authors: Jin Xueli , Wang Haifeng , Wang Jiawei
Published: January 2022

The comprehensive utilization of red mud had become a common problem in alumina industry. This paper presented a method for preparing red mud non burning cementitious material without frost return. The red mud from an aluminum oxide plant in Guizhou was used as the research object, and the effects of excitation time on compressive and flexural strength were investigated. The better compressive and flexural strength were obtained when the excitation time was 6h. The compressive strength were 15.62Mpa, 18.55Mpa and 15.6Mpa respectively, and the flexural strength were 2.86Mpa, 3.58Mpa and 3.54Mpa respectively when they were mainted for 7 days, 28 days and immersion for 24 hours, which met the strength requirements of MU15. The sodium in red mud was transformed into stable sodium aluminum hydroxysilicate Al3Na4(OH)(SiO4)3 phase finally, and the concentration of Na+ in the leaching solution extracted by horizontal shaking method was about 370mg/L, so it would not cause frost return to the non burning cementitious material. This study would open up a new way for the mass consumption of red mud.
Windows into the past: lake sediment phosphorus trajectories act as integrated archives of watershed disturbance legacies over centennial scales
Authors: Bhattacharya Ruchi , Lin Simon G M , Basu Nandita B
Published: January 2022

Historic land alterations and agricultural intensification have resulted in legacy phosphorus (P) accumulations within lakes and reservoirs. Internal loading from such legacy stores can be a major driver of future water quality degradation. Yet, little is known about the magnitude and spatial patterns of legacy P accumulation in lentic systems, and how watershed disturbance trajectories drive these patterns. Here, we used a meta-analysis of 113 paleolimnological studies across 124 lakes and four reservoirs (referred here on as lakes) in 20 countries to quantify the linkages between the 100 year trajectories of P concentrations in lake sediments, watershed inputs, and lake morphology. We find five distinct clusters for lake sediment P trajectories, with lakes in the developing and developed world showing distinctly different patterns. Lakes in the developed world (Europe and North America) with early agricultural intensification had the highest sediment P concentrations (1176–1628 mg kg−1), with a peak between the 1970–1980s and a decline since then, while lakes in the developing world, specifically China, documented monotonically increasing sediment P concentrations (857–1603 mg kg−1). Sediment P trajectories reflected watershed disturbance patterns and were driven by a combination of anthropogenic drivers (fertilizer input and population density) and lake morphology (watershed to lake area ratio). Specifically, we found the largest legacy accumulation rates to occur in shallow lakes experiencing long-term land-use disturbances. These links between land-use change and P accumulation in lentic systems can provide insights about inland water quality response and help to develop robust predictive models useful for resource managers and decision-makers.
Performance evaluation of four-wheel driving wheel tractor with diesel engine using biodiesel fuel
Authors: Sasmito D A , Mulyantara L T , Budiman A
Published: January 2022

The Indonesian government is committed to increasing biodiesel usage as renewable energy by 23% of national energy consumption by 2025. Implementing the mandatory biodiesel program must be carried out sustainably to help reduce fossil energy consumption, reduce air pollution, and reduce the effect of greenhouse gases. The Ministry of Agriculture studied applying biodiesel from palm oil in agricultural machinery, especially four-wheeled tractors, to help implement agricultural mechanization in Indonesia. The research objective was to determine the effect of biodiesel on the performance of a four-wheeled tractor engine in several variations of the mixture to obtain the composition of biodiesel mixture that gave optimal engine performance. The experiment was conducted by testing the performance of a four-wheeled tractor engine on a laboratory scale referring to SNI 7146-2019, using biodiesel fuel with a mixture of B10 to B100 variations. The result showed that biodiesel affects the performance of a four-wheeled tractor engine. The efficiency of continuing engine power using biodiesel was the largest at B20 of 80.15% at the maximum governor and 80.97% at the standard PTO rotation of 540 rpm. The smallest power forwarding efficiency on the B100 was 76.12% at the maximum governor and 76.55% at 540 rpm PTO rotation. Biodiesel B20 provided the greatest maximum power of 23.55 kW, 44 kgf of torque, specific fuel consumption of 250.54 g/kW hours. At 540 rpm, PTO rotation produced a maximum power of 23.79 kW, 42 kgf of torque, the specific fuel consumption of 256.12 g/kW hours
Hydrodynamic study of internal circulation inside microreactor for transesterification process
Authors: a/l S Rae V R , Laziz A M , Shaari K Z K
Published: January 2022

Microreactors are important devices used in the field of process intensification. The use of microreactors offers several advantages, such as larger surface area to volume ratio, increasing mass and heat transfer rates, easy control of reagents and reactions, as well as easy scalability. The hydrodynamics within the microreactor produce several flow patterns, such as annular, parallel, and slug flow. Slug flow is of particular interest as it allows for greater mass transfer as mass transfer occurs not only at the interface but also within the internal circulations of the slug. The aim of this research was to investigate the formation of these internal circulations of these slugs under different parameters and how these internal circulations affect the mass transfer of the process. An inverted microscope was used to visualize the flow patterns of the internal circulation with the help of dye or small particles. The slug shape remains relatively unchanged at different catalyst concentrations, flowrates and oil-to-methanol ratios, and the internal circulations formed in the slugs remain fully formed regardless of the slug size. It can be said that process intensification of transesterification utilizing microreactor is a viable option and can be further improved with optimal parameters.