bluuebunny/crossref_metadata_2025 huggingface dataset:
Unveiling the role of glassy nanodomains in strength and plasticity of crystal–glass nanocomposites via atomistic simulation
Authors: Gan Kefu , Li Zhiming
Published: February 2022

Crystalline metals and alloys are usually ductile owing to lattice dislocations and various slip systems, while bulk metallic glasses show ultrahigh yield strength with very limited plasticity. Combining the crystalline and glassy phases in one alloy has recently been shown to be promising for achieving both ultrahigh strength and good deformability. Yet, it is challenging to capture the dynamic dislocation behavior through the deformation process and elucidate the role of glassy domains on the excellent mechanical performance of the nanocomposites. Here, we unveil and visualize the atomic-scale interactions among dislocations, glassy nanodomains, and crystal–glass interfaces in a specially designed configuration via molecular dynamics simulation. The glassy nanodomains occupying the triple junctions of grain boundaries are found to optimize the dynamic partitioning of shear strains between the two phases, thus manipulating the production of both dislocations in the crystalline matrix and shear transformation zones in the glassy nanodomains. The crystal–glass interfaces where strain concentration can occur function as both dislocation sources and sinks for plasticity, which in turn alter the strain distributions in the two phases. Systematic observations further suggest that the glassy nanodomains can dynamically tune the dislocation content and configuration in the crystalline matrix throughout the deformation. The unveiled mechanisms thus open a pathway for the development of novel ultrahigh-strength and ductile materials by tuning dislocation behavior in the crystalline matrix via glassy nanodomains.
Insight into interface electrical properties of metal–oxide–semiconductor structures fabricated on Mg-implanted GaN activated by ultra-high-pressure annealing
Authors: Wada Yuhei , Mizobata Hidetoshi , Nozaki Mikito , Kobayashi Takuma , Hosoi Takuji , Kachi Tetsu , Shimura Takayoshi , Watanabe Heiji
Published: February 2022

GaN-based metal–oxide–semiconductor (MOS) devices, such as n- and p-type capacitors and inversion- and accumulation-type p-channel field effect transistors (MOSFETs), were fabricated by Mg-ion implantation and ultra-high-pressure annealing (UHPA) under 1-GPa nitrogen pressure. Even though UHPA was conducted at 1400 °C without protective layers on GaN surfaces, n-type MOS capacitors with SiO2 gate dielectrics formed on non-ion-implanted regions exhibited well-behaved capacitance–voltage characteristics with negligible hysteresis and frequency dispersion, indicating distinct impact of UHPA in suppressing surface degradation during high-temperature annealing. Efficient activation of the implanted Mg dopants and reasonable hole accumulation at the SiO2/GaN interfaces were also achieved for p-type capacitors by UHPA, but the fabricated inversion- and accumulation-type p-channel GaN MOSFETs were hardly turned on. The findings reveal extremely low hole mobility at GaN MOS interfaces and suggest an intrinsic obstacle for the development of GaN-based MOS devices.
Natural biomaterial honey-based resistive switching device for artificial synapse in neuromorphic systems
Authors: Sueoka Brandon , Cheong Kuan Yew , Zhao Feng
Published: February 2022

Resistive switching is a promising technology for artificial synapses, the most critical component and building block of a neural network for brain-inspired neuromorphic computing. The artificial synapse is capable of emulating a signal process and memory functions of biological synapses. The artificial synapse fabricated by natural bioorganic materials is essential for developing soft, flexible, and biocompatible electronics and sustainable, biodegradable, and environmentally friendly neuromorphic systems. In this work, a natural biomaterial—honey based resistive switching device—was demonstrated to emulate some important functionalities of biological synapses, including synaptic potentiation and depression, short-term and long-term memory, spatial summation, and shunting inhibition. The results indicate the potential of honey based resistive switching for artificial synaptic devices in renewable neuromorphic systems and bioelectronics.
Sizing the depth and width of ideal delaminations using modulated photothermal radiometry
Authors: Salazar Agustín , Mendioroz Arantza
Published: February 2022

Delaminations, buried defects parallel to the sample surface, reduce the material stiffness and the structure reliability. Photothermal methods, based on exciting the surface by a light beam and analyzing the resulting temperature rise, have been extensively used for detecting delaminations and sizing their depth. However, less attention has been paid to the sizing of the delamination width. In this work, we use modulated photothermal radiometry (PTR) to size the depth and width of narrow delaminations by fitting the theoretical temperature expression to the experimental frequency spectrum of the PTR signal. We have established a detectability limit: for good thermal conductors, submicronic delaminations can be sized down to 10 mm, whereas for thermal insulators, it is difficult to go below 0.5 mm. Experiments on calibrated delaminations confirm these predictions.
CSIRO CAFE-60 submissions to the World Meteorological Organization operational decadal forecasts and the international multi-model data exchange
Authors: Collier Mark A. , O’Kane Terence J. , Kitsios Vassili , Sandery Paul A.
Published: February 2022

The Climate Analysis Forecast Ensemble (CAFE) system was developed by the Decadal Climate and Forecasting Project (DCFP) within the CSIRO Climate Science Centre (CSC) with the express purposes of providing operational ensemble forecasts of the near-term climate (1–10 years) and meeting the requirements of becoming a World Meteorological Organization (WMO) Global Data Producing Centre (GDPC) from which output has been provided in the UK Met Office (UKMO) international, multi-model data exchange. This CAFE-60 submission satisfied, at least, the minimum requirements for the CSC to become a Global Producing Centre for Annual-to-Decadal Climate Prediction (GPC-ADCP) of the WMO Lead Centre for Annual-to-Decadal Climate Prediction. In practical terms, this has meant running the CAFE-60 version 1 modelling system for years 1960–2020, or a 61-year set, with a modest ensemble size of 10. Each decade-long forecast was initialised from the beginning of each November using a state-of-the-art assimilation methodology, and delivering the minimum requested data to the coordinating centre within the UKMO. The number 60 in CAFE-60 refers to the initial year of the assimilation, 1960, where we believe there is adequate observational data to produce a meaningful reanalysis output product for wide scientific application. This document describes the key features of the CAFE-60 assimilation and forecasting system, the climate and forecasting conforming post-processed datasets along with how to access the datasets via the CSIRO Data Access Portal, and the quality control measures implemented to achieve the highest possible data quality and delivery. Part of becoming a Data Producing Centre is the ongoing need to supply CAFE-60 forecast data, at least on an ongoing annual basis, to the UKMO; therefore, obtaining CAFE-60 operational status requires significant ongoing resources and efforts to continue. In addition to the annual dataset submission by the DCFP as a minimum requirement of being declared a Data Contributing Centre, a separate application from the Australian Permanent Representative with WMO (Dr Andrew Johnson) was required to obtain the GPCP status; this was completed in early September 2020, making CSIRO one of only five centres with this special GPC-ADCP status currently in the world.
Socioeconomic disadvantage and the practice location of recently Fellowed Australian GPs: a cross-sectional analysis
Authors: Moad Dominica , Fielding Alison , Tapley Amanda , van Driel Mieke L. , Holliday Elizabeth G. , Ball Jean I. , Davey Andrew R. , FitzGerald Kristen , Bentley Michael , Spike Neil A. , Kirby Catherine , Turnock Allison , Magin Parker
Published: February 2022

Background: Socioeconomic disadvantage and the ‘inverse care law’ have significant effects on the health and well-being of Australians. Early career GPs can help address the needs of socioeconomically disadvantaged communities by choosing to practice in these locations. This study addressed an evidence gap around GPs post-Fellowship (within 2 years) practice location, and whether practice location is related to postgraduate vocational training. Methods: This was a cross-sectional questionnaire-based study of recently Fellowed GPs from New South Wales, the Australian Capital Territory, Victoria and Tasmania. Questionnaire items elicited information about participants’ current practice, including location. Where consent was provided, participants’ questionnaire responses were linked to previously collected vocational GP training data. The outcome factor in analyses was practice location socioeconomic status (SES): the four deciles of greater socioeconomic disadvantage versus locations with a higher SES. SES was classified according to the Socio-Economic Indexes for Areas – Index of Relative Socioeconomic Disadvantage. Multivariable logistic regression was undertaken. Results: Of participants currently working in clinical general practice, 26% were practicing in the four deciles of greater socioeconomic disadvantage. Significant multivariable associations of working in these locations included having trained in a practice located in an area of greater socioeconomic disadvantage (odds ratio (OR) 3.14), and having worked at their current practice during vocational training (OR 2.99). Conclusion: Given the association of training and practice location for recently Fellowed GPs, policies focused on training location may help in addressing ongoing workforce issues faced by areas of higher socioeconomic disadvantage.
Elevated shear rate‐induced by exercise increases eNOS ser1177 but not PECAM‐1 Tyr713 phosphorylation in human conduit artery endothelial cells
Authors: Tryfonos Andrea , Rasoul Debar , Sadler Daniel , Shelley James , Mills Joseph , Green Daniel J. , Dawson Ellen A. , Cocks Matthew
Published: February 2022

Although evidence demonstrates the fundamental role of shear stress in vascular health, predominantly through the release of nitric oxide (NO), the mechanisms by which endothelial cells (EC)s sense and transduce shear are poorly understood. In cultured ECs tyrosine phosphorylation of PECAM‐1 has been shown to activate eNOS in response to shear stress. However, in the human skeletal muscle microcirculation PECAM‐1 was not activated in response to exercise or passive leg movement. Given this contradiction, this study aimed to assess the effect of exercise on conduit artery PECAM‐1 and eNOS activation in humans. Eleven males were randomised to two groups; 30 min of handgrip exercise (n = 6), or a time‐control group (n = 5). Protein content of eNOS and PECAM‐1, alongside eNOS Ser1177 and PECAM‐1 Tyr713 phosphorylation were assessed in ECs obtained from the radial artery pre‐ and post‐intervention. Handgrip exercise resulted in a 5‐fold increase in mean shear rate in the exercise group, with no change in the control group (group*time, P < 0.001). There was a 54% increase in eNOS Ser1177 phosphorylation in the exercise group, when compared to control group (group*time, P = 0.016), but no change was reported in PECAM‐1 Tyr713 phosphorylation in either group (group*time, P > 0.05). eNOS and PECAM‐1 protein content were unchanged (group*time, P > 0.05). Our data show that exercise‐induced elevations in conduit artery shear rate increase eNOS Ser1177 phosphorylation but not PECAM‐1 Tyr713 phosphorylation. This suggests PECAM‐1 phosphorylation may not be involved in the vascular response to acute but prolonged elevations in exercise‐induced shear rate in conduit arteries of healthy, active men.
Analysis of correlations in strong field ionization
Authors: Ivanov I A , Kim Kyung Taec
Published: February 2022

We propose to use correlation function analysis as a tool for the study of strong field ionization. We show, in particular, that study of the correlations of electron’s coordinate and velocity reveals patterns which can be naturally interpreted as manifestations of the electron’s exit point (the spatial point where the electron exits the tunneling barrier). This analysis provides an unambiguous definition of the exit point. The location of the exit point thus determined agrees well with the estimates used in the semiclassical simulations.
Chemically imaging nanostructures formed by the covalent assembly of molecular building blocks on a surface with ultrahigh vacuum tip-enhanced Raman spectroscopy
Authors: Schultz Jeremy F , Li Linfei , Mahapatra Sayantan , Jiang Nan
Published: February 2022

Surface-bound reactions have become a viable method to develop nanoarchitectures through bottom-up assembly with near atomic precision. However, the bottom-up fabrication of nanostructures on surfaces requires careful consideration of the intrinsic properties of the precursors and substrate as well as the complex interplay of any interactions that arise in the heterogeneous two-dimensional (2D) system. Therefore, it becomes necessary to consider these systems with characterization methods sensitive to such properties with suitable spatial resolution. Here, low temperature ultrahigh vacuum scanning tunneling microscopy (STM) and tip-enhanced Raman spectroscopy (TERS) were used to investigate the formation of 2D covalent networks via coupling reactions of tetra(4-bromophenyl)porphyrin (Br4TPP) molecules on a Ag(100) substrate. Through the combination of STM topographic imaging and TERS vibrational fingerprints, the conformation of molecular precursors on the substrate was understood. Following the thermally activated coupling reaction, STM and TERS imaging confirm the covalent nature of the 2D networks and suggest that the apparent disorder arises from molecular flexibility.
Liquid film characteristics measurement based on NIR in gas–liquid vertical annular upward flow
Authors: Zhao Zhiyue , Wang Baohui , Wang Jing , Fang Lide , Li Xiaoting , Wang Fan , Zhao Ning
Published: February 2022

Liquid film plays a crucial role in void fraction, friction pressure drops, momentum and heat transfer in the two-phase flow. The film thickness measurement experiments of annular flow at four pressure conditions have been conducted using near-infrared sensor. The signal is processed by variational mode decomposition, whose parameters are optimized using the sparrow search algorithm. The envelope spectrum and Pearson correlation coefficient judgment criteria were adopted for signal reconstruction, and the value of the liquid film thickness is obtained. The effect (such as flow rate, pressure, entrainment, etc) of the liquid film thickness are analyzed theoretically. The characterization parameters Weg″, Wel, Nμl
and X
mod have been extracted and optimized, and a new average liquid film thickness correlation is proposed. The laboratory results indicate that the mean absolute percentage error of the predictive correlation is 4.35% (current data) and 12.02% (literatures data) respectively.
Enhancement of the mechanical and thermal transport properties of carbon nanotube yarns by boundary structure modulation
Authors: Shikata Ryo , Suzuki Hiroo , Hayashi Yuta , Hasegawa Taisuke , Shigeeda Yuho , Inoue Hirotaka , Yajima Wataru , Kametaka Jun , Maetani Mitsuaki , Tanaka Yuichiro , Nishikawa Takeshi , Maeda Satoshi , Hayashi Yasuhiko , Hada Masaki
Published: February 2022

Carbon nanotubes (CNTs) exhibit extremely high nanoscopic thermal/electrical transport and mechanical properties. However, the macroscopic properties of assembled CNTs are significantly lower than those of CNTs because of the boundary structure between the CNTs. Therefore, it is crucial to understand the relationship between the nanoscopic boundary structure in CNTs and the macroscopic properties of the assembled CNTs. Previous studies have shown that the nanoscopic phonon transport and macroscopic thermal transport in CNTs are improved by Joule annealing because of the improved boundary Van-der-Waals interactions between CNTs via the graphitization of amorphous carbon. In this study, we investigate the mechanical strength and thermal/electrical transport properties of CNT yarns with and without Joule annealing at various temperatures, analyzing the phenomena occurring at the boundaries of CNTs. The obtained experimental and theoretical results connect the nanoscopic boundary interaction of CNTs in CNT yarns and the macroscopic mechanical and transport properties of CNT yarns.
A power-balance model for the L-mode radiative density limit in fusion plasmas
Authors: Zanca P , Sattin F , Escande D F , Auriemma F
Published: February 2022

A 1D cylindrical power-balance model of the radiation density limit (DL) gives a unified description of this phenomenon for stellarators, reversed field pinches and L-mode tokamaks (Zanca et al 2019 Nucl. Fusion
59 126011). The DL scaling laws for the three different configurations are all derived from a combination of just two equations: (a) a single-fluid heat-transport equation; (b) on-axis Ohm’s law with Spitzer resistivity, taken in a suitable limit for the stellarator. Here, we present a refined version of the model, alongside further experimental evidence supporting its successful application.
Advanced experimental-based data-driven model for the electromechanical behavior of twisted YBCO tapes considering thermomagnetic constraints
Authors: Yazdani-Asrami Mohammad , Sadeghi Alireza , Seyyedbarzegar Seyyed Meysam , Saadat Amirhossein
Published: February 2022

Data-driven models can predict, estimate, and monitor any highly nonlinear and multi-variable behaviour of high-temperature superconducting (HTS) materials, and superconducting devices to analyse their characteristics with a very high accuracy in an almost real-time procedure, which is a significant figure of merit as compared with traditional numerical approaches. The electromechanical behaviour of twisted HTS tapes under different strains, magnetic fields, and temperatures is a complicated problem to be solved using conventional approaches, including finite element-based methods, otherwise, experimental testing is needed to characterise it. This paper aims to offer a data-driven model based on artificial intelligence techniques to predict the electromechanical behaviour of HTS tapes operating under various thermomagnetic conditions. By using the proposed model, normalised critical current value and stress of twisted tapes can be predicted under different temperatures and magnetic flux densities. For this purpose, experimental data were used as inputs to design an adaptive neuro-fuzzy inference system (ANFIS). To achieve the best performance of the prediction system, multiple clustering methods were used, such as the grid partitioning method, fuzzy c-means clustering method, and sub-clustering method. Sensitivity analyses were conducted to find the best architecture of ANFIS to predict and model electromechanical behaviour of twisted tapes with high accuracy.
Quantum consensus dynamics by entangling Maxwell demon
Authors: Ryu Sungguen , López Rosa , Toral Raúl
Published: February 2022

We introduce a Maxwell demon which generates many-body entanglement robustly against bit-flip noises, allowing us to obtain quantum advantage. Adopting the protocol of the voter model used for opinion dynamics approaching consensus, the demon randomly selects a qubit pair and performs a quantum feedback control, in continuous repetitions. We derive upper bounds for the entropy reduction and the work extraction rates by the demon’s operation. These bounds are determined by a competition between the quantum–classical mutual information acquired by the demon and the absolute irreversibility of the feedback control. Our finding of the upper bounds corresponds to a reformulation of the second law of thermodynamics under a class of Maxwell demon which generates many-body entanglement in a working substance. This suggests that a general condition for the operation of a successful entangling demon, one for which many-body entanglement stabilization and work extraction are possible, is that the information gain is larger than the absolute irreversibility.
Enhanced magnetic properties of SrFe12O19 through exchange-coupled nanocomposite
Authors: Lamouri R , Fkhar L , Mounkachi O , Mahmoud A , Boschini F , Hamedoun M , Salmani E , Kim K H , Ali M Ait , Benyoussef A , Ez-zahraouy H
Published: February 2022

This work presents the synthesis and characterization of hard/soft (1-x)SrFe12O19/xCoFe2O4 exchange-coupled nanocomposites with x = 0.0, 0.05, 0.1, and 0.2 using the conventional coprecipitation and ball milling preparation methods followed by heat treatment. CoFe2O4 material was used as a soft magnetic material when the effects of its concentration on the structural and magnetic properties of the obtained nanocomposites were investigated using different characterization techniques. Structural and microstructural analyses showed the presence of both spinel ferrite and the M-type hexaferrite phase. Single-phase magnetic loops were observed for the prepared nanocomposites, indicating an exchange coupling interaction between CoFe2O4 and SrFe12O19 phases. To support this finding, a Henkel plot was performed, which revealed the presence of strong exchange coupling interaction in CS5 compared to CS10, unlike CS20, where the dipolar interaction is dominant. The obtained results demonstrate the possibility of enhancing the (BH)max of the M-type strontium hexaferrite through an exchange-coupled nanocomposite, using a simple and reproducible synthesis process with a small content of the soft magnetic phase.
Study on the handheld monitoring equipment and the supervisory method for transportation loss of oil tank trucks
Authors: Zhizhou He , Zuobi Wang , Hua Ma , Shideyi  , Hejingbin  , Zhaoxia Mu , Yuanbo Bai
Published: February 2022

At present, the oil of oil fields in remote areas and well sites without petroleum pipeline are mainly transported by oil tankers. Oil will spill and be stolen during the process of transportation, resulting in a large difference between the amount of oil loaded at first and the amount of oil unloaded in the end. The traditional method is to measure and print the bill when loading oil, not to re-measure when unloading oil, and to pay according to the bill, which causes great economic loss. Aiming at tackle this problem, this paper designs and realizes a handheld monitoring device and supervision method for the transportation loss of oil tanker. It integrates EEPROM, RTC real-time clock, PCF8563T memory, LED display lamp, LCD1602 display screen and speakers, and communicates and transmits oil quantity information with primary instruments of oil pumping equipment and oil unloading equipment, the information stored by the device can be read by the communication software of the host computer, and the information can be analyzed, calculated and settled accurately by the management software of the host computer. It can effectively prevent oil leakage and oil stealing during transportation.
Optimal control of high speed unmanned vehicle path tracking
Authors: Fan Shengwen , Xie Tao , Chen Zhigang , Hu Xuan , Gao Lei
Published: February 2022

In order to ensure the accuracy and stability of tracking control of driverless vehicle at high speed, an improved model predictive control method was designed. First of all, for the current high-speed unmanned vehicle tracking control field, there is little research and the tracking accuracy is poor. Starting from the three-degree-of-freedom vehicle dynamics model, by analyzing the vehicle yaw stability, the model is added with envelope constraints, and the linear time is derived. The variable path tracking controller model is designed with or without additional constraints. Through Matlab and CarSim co-simulation, it is shown that the MPC controller with envelope constraint has higher tracking accuracy than the ordinary MPC controller, and the vehicle has better robustness to the road adhesion coefficient, and the vehicle driving stability is significantly improved.
Numerical Study on the Effect of Transverse Baffles on the Stability of Iron Concentrate in a Cargo Hold
Authors: Wang Anqi , Zhang Jianwei , Wang Zhanwei
Published: February 2022

Cargo fluidization is one of the main causes of ship capsizing accidents, which has been concerned by International Association of Classification Societies. Iron concentrate is regarded as the research object, its movement in the cargo hold is simulated using discrete element method. To effectively reduce the sloshing amplitude of cargo in the cargo hold, four conditions that considering the transverse baffles are designed. The stability of cargo is analyzed in detail from the offset of cargo gravity center and the contact force on the bulkhead induced by the cargo movement. Numerical simulation results show that the installation of transverse baffles can effectively reduce the sloshing amplitude of cargo in the cargo hold. Especially, it can better restrain the variation of center of gravity of cargo in the y-direction. The study focuses on the influence of baffles with different lengths on the stability of cargo in the cargo hold, which can provide a reference for the prevention of bulk carrier accidents.
Cooperative control mechanism of key objects and key nodes of dry bulk terminal
Authors: Shi Hankun , Wang Xuelin , Zhang Zhaolun
Published: February 2022

Based on the operation process of dry bulk terminal and according to the unique process characteristics of dry bulk terminal, this study combs the specific distribution of key objects and key nodes of dry bulk terminal. Based on the analysis of the process mechanism and interactive information of dry bulk terminal, the collaborative control mechanism of key objects and key nodes is studied, which creates a certain theoretical framework for the automation and intelligent design of dry bulk terminal.
Dynamic regulation method of distributed generation in distribution network under 5G network
Authors: Chen Duanyun , Li Yuanjiu , Bai Jie , Zhang Hongpo , Xie Shimulin , Tang Zeyi , Liu Xujie
Published: February 2022

Aiming at the problem of uneven power flow distribution caused by distributed power supply access, which leads to high voltage deviation and active network loss, a dynamic control method of distributed power supply in 5G network is proposed. The distributed topology structure of the distribution network under 5G network is generated, and the static topology information is extracted to establish the power partition. The distribution network in each area is connected to its own bus through different feeders. The distribution network reconstruction period is divided in the partition, and the network reconstruction period and the corresponding switch action scheme are determined. The state of distributed power supply was estimated according to reconstruction period and active/reactive power balance index, and the stability of dynamic control was determined. Based on the stability control, the dynamic control model of distributed power supply is established, and the network voltage can reach the preset target by adjusting the power of power switch. The simulation results show that the average voltage deviation of the proposed control method is 1.976, which is 4.431 and 3.783 lower than those based on data drive and flexible load regulation, respectively. The active power network loss of the control method in this paper is 0.342 MW, which is 0.385 MW and 0.346 MW lower than that of the control method based on data drive and flexible load regulation, respectively. Therefore, this method can improve the absorption capacity of distributed power supply and promote the power flow reciprocity of distribution network.
Forecasting Method of Energy Demand of Integrated Energy System Considering Seasonal Catastrophe
Authors: Hua Qingsong , Li Qiang , Gao Shengyu , Liu Yongqing , Zhu Hong , Zhu Zhengyi , Shuai Qilin
Published: February 2022

The change of season will cause a variety of factors affecting energy demand to change, resulting in severe fluctuations in energy demand. Accurate prediction is of great value for energy management. Therefore, a prediction method of energy demand of integrated energy system considering seasonal mutation is proposed. Based on the analysis of the basic concepts, attributes and influencing factors of energy and energy demand, a seasonal energy demand impact decomposition model is constructed by lmdi-i to decompose the impact of season on energy demand. By dividing the energy indicators of the integrated energy system, a fuzzy neural network with error output and correction mechanism is established to predict energy demand. The test results show that the maximum relative error of the prediction results of the design method is 5.89%, the minimum relative error is 1.03%, the average absolute error is 3.21%, the root mean square error is 0.019, and the hill inequality coefficient is 0.020. Are better than the comparison method.
Research status of partial discharge detection of power transformer based on pulse current method
Authors: Sun Jiahao , Pan Shuyan , Deng JinZhao
Published: February 2022

There are many important equipment running in the power grid, and the power transformer is one of them. It plays an extremely important role in the stable operation of the power system. Therefore, whether the power transformer can operate safely and stably becomes particularly important. When the power transformer is running online, partial discharge will occur if there are insulation defects, which will further develop into breakdown without timely detection and treatment. The insulation inside the transformer often has certain defects and produces certain partial discharge, and the partial discharge signal is often a high-frequency pulse signal. In this paper, the definition of partial discharge, the generation process of pulse current and the detection method of transformer partial discharge based on pulse current method will be introduced in detail. Several common methods are combed and summarized, the current development status of pulse current method is introduced, and the possible research direction in the future is prospected.
Optimal Control Measures For Dynamic Stability Level Of Northeast Power Grid
Authors: Lu Shi xuan , Shao Yang di , Ye Peng , Sun Tian he , Wang Xue jie , Zhang Hong peng , Li Chun shan
Published: February 2022

Due to the rapid development of new energy such as nuclear power at the transmission end of Northeast power grid, the improvement of transmission capacity of Lugu UHVDC and the large-scale development of power base, the problem of dynamic stability of Northeast Power Grid has surfaced. Based on the reality of Northeast power grid, this paper deeply and carefully carries out the dynamic stability level analysis of Northeast power grid from three aspects of source, network and load, studies the effective methods and measures to improve the damping ratio and robustness of main vibration modes between power grid regions, takes into account the scientificity, systematicness and scientificity of the measures, and provides reference for domestic and foreign related grid operation.
A Method of Integrated Energy Metering Simulation Data Generation Algorithm Based on Variational Autoencoder WGAN
Authors: Zhang Penghe , Xue Yang , Song Runan , Yang Yining , Wang Cong , Yang Liu
Published: February 2022

With the development of integrated energy systems, the penetration rate of all types of distributed power sources continues to increase. In a grid oriented to integrated energy metering, the metering business of different energy sources needs to fully consider the dynamic characteristics of different user loads. This paper aims at the generation of large-scale integrated energy metering data in large-scale integrated energy digital simulation technology, starting from supporting the construction of an integrated energy metering simulation system, combining various business applications and artificial intelligence technology under the background of the energy Internet. For the requirements of energy metering simulation, a method of integrated energy metering simulation data generation based on variational autoencoder WGAN is proposed, and the effect of the method proposed in this paper is verified through actual metering scene data.
Research on the Semantic Composite Network Recognition Method of Power Distribution DTU Automation Acceptance Virtual Seat System
Authors: Liu Hongwei , He Yuwei , Jiang Jian , Liu Xingye , Cui Haoyang
Published: February 2022

Aiming at semantic inaccurate recognition problem caused by the lack of professional vocabulary in the existing corpus, a composite network recognition method for the semantics of the power distribution DTU acceptance virtual agent system is proposed. This method is used to extract and merge the entity, attribute and relationship information of power equipment from multiple data sources to construct a power distribution DTU acceptance knowledge graph. In addition, the graph database is the main body and the SQL database is the extension, and the corpus is stored in a distributed manner. The acceptance test results show that the overall recognition rate of the system platform for the instructions issued by the acceptance personnel in the complex environment is 92.8%, which reduces the acceptance time by more than 70%.
Study on insulation performance optimization of EMU high-voltage equipment box
Authors: Li Chao , Lin Lin , Qu Weidong
Published: February 2022

The EMU high-voltage electrical equipment on the roof not only bears the erosion of various harsh and extreme environments, but also bears the impact of various over-voltage, and the insulation performance of the electrical equipment on the roof is seriously threatened. This paper studies the insulation optimization design method of EMU high-voltage electrical equipment, puts forward the method of adding a certain length of insulating sheath on the electrical equipment to improve the insulation performance of high-voltage equipment box, and tests the insulation optimization measures on high-voltage circuit breaker and EMU high-voltage cable. The result shows that the installation of insulating sheath is feasible to improve the insulation performance of EMU high-voltage equipment box.
Effect of surface treatment materials on frost resistance of damaged concrete
Authors: Li Tianlun , Wu Yonggen
Published: February 2022

In order to study the effect of silicate infiltration agent, tetraethyl orthosilicate and nano-SiO2 surface treatment materials on the freezing resistance of damaged concrete, the peeling condition of damaged concrete after soaking in salt water was tested by single-side freeze-thaw method. The results showed that tetraethyl orthosilicate and silicon infiltration agent can effectively improve the damaged concrete frost resistance and can reduce the 7 d water quantity of concrete, the most significant is the effect of tetraethyl orthosilicate, 7 d water quantity reduced rate of 65%, after 28 times freeze-thaw cycle exfoliation volume is 679 g/m2. Silicon infiltration agent surface treatment also has a good effect, can increase the number of freeze-thaw cycles 8 times. Nano-SiO2 has the worst treatment effect and can not improve the number of freeze-thaw cycles of damaged concrete.
A fault-tolerance control method of load frequency based on reverse behavior reconstruction
Authors: Xue Fei , Zhang Hanhua , Zhang Shuang , Zhou Lei , Yang Ting , Li Hao
Published: February 2022

The access of a high proportion of renewable energy and the large-scale application of open sharing communication network are the two main characteristics of modern interconnected power grid. However, the tight coupling between the cyber and physical subsystem makes the malicious network attack and sudden physical failure more likely to cause the collapse of the interconnected power grid. Therefore, a reverse behavior reconstruction strategy is proposed, which does not need to obtain a priori fault information and only depends on the input and output measurements of the system, so as to realize fault tolerance as much as possible. The simulation experiments show that the proposed strategy can achieve the frequency fault tolerance and has better practicability and applicability under complex and diverse fault conditions.
Parallel Simulation of The Electromechanical Transient Phenomena of Power System via Modern Software Development Technique
Authors: Xie Yu , Wu Zhigang , Zhou Erzhuan
Published: February 2022

The simulation of power system electromechanical transient phenomena is highly dependent on the knowledge and model of special domain. For this reason, traditional parallelization of the simulation must be coupled with concrete algorithm and code. In this paper, a parallelized electromechanical transient simulation program is proposed based on the open-source simulation engine called InterPSS and general open object-oriented modelling framework. The correctness and effectiveness of this framework have been verified by a large-scale simulation case.
Characterization and Modeling of SiC MOSFET Modules for High-voltage Applications
Authors: Hao Yi , Li QingPing , Xu YunFei , Cui Lǜ , Li WeiGuo , Lu JuanJuan
Published: February 2022

This paper presents a detailed characterization and modeling of 6.5kv SiC MOSFET half-bridge module. Based on the equivalent circuit topology, the model parameters are extracted from the data manual and test data, and the behavior model is constructed to describe the static and dynamic characteristics of the device. This paper used behavioral model functions, and carries out parameter extraction and model fitting for new devices. The model is verified by double pulse test under inductive load. The verification results show that the modeling work is correct and effective, it can predict the switching performance of devices in high voltage applications.
Evaluation Method of 500kV Transformer Bushing Insulation State Based on Active Power Loss
Authors: Gu Zhaoliang , Xu Ran , Li Zhen , Li Xiaolei , Wang Yaguan , Xu Wei , Yi Feng , Gao Zhixin
Published: February 2022

The bushing is one of the most important components of power transformer, and it is very important to find the internal defects of bushings as soon as possible, effectively and accurately diagnose its insulation state information. In this paper, the active power loss of 500kV transformer bushings have been analyzed, and the insulation state evaluation method based on active power loss is proposed. To verify the feasibility of evaluation method, one abnormal 500kV transformer bushing was selected to analyze its insulation state. The result shows that this method can be used as a powerful complement to tarδ.
The FEM Analysis of the Height Protection Equipment of the Crane
Authors: Wang Jingdong , Qin Hao , Wang Bin , Xu Xiudong
Published: February 2022

According to the statistical data of special equipment accidents, and in accordance with the requirements of the "double limit" policy, the height limit device of hoisting machinery includes a variety of types, focusing on the two representative types of fire interrupter device and mechanical drive height limit. By establishing a CAD model of the corresponding device mechanism structure, using the finite element method, simulating the movement of the device mechanism, analyzing the force of the structure, and obtaining relevant information, the cause and mechanism of the device failure can be obtained, and then from the design, manufacture, installation and the use of the device. Reliability improvement and enhancement are carried out in multiple links such as inspection.
Analysis of Flow Characteristics of Different Shape Particles Chasing
Authors: Xu Xiaodong , Zeng Zhuoxiong , Guo Kaifang
Published: February 2022

in order to study the gas flow characteristics of particles with different shapes in the pursuit process, spherical, ellipsoidal and square particles are selected for numerical simulation by fluent. The results show that when the pursuit speed is the same, the streamline produced by square particles in the pursuit process is denser than that of spherical and ellipsoidal particles. Particle movement creates a certain vacuum on both sides and rear of the particle, causing the surrounding air flow to enter the areas on both sides of the particle, resulting in strong turbulence. After the rear particles catch up with the front particles, the changes of the surrounding flow field and streamline are similar to the inverse process before catching up, indicating that the particle motion has a certain regularity, and the square particles have the largest turbulent kinetic energy among the three particles.
Study on the Rheology of AlSi4Mg2 Alloy at Steady State
Authors: Ju Liping , Guan Yanlong , Luo Hongchao
Published: February 2022

The rheological characteristics of AlSi4Mg2 alloy at steady state are studied theoretically based on the ICF model. It is shown that the solid volume fraction and shear rate have obvious effect on the rheological behaviour. Specifically, the apparent viscosity increases when the solid volume fraction increases and the shear rate decreases, the corresponding microstructure parameter n has the similar trend. It shows that there is a closely relationship between the steady state viscosity and its microstructure. The AlSi4Mg2 alloy has the pseudoplastic behaviour. The agreement of theoretical prediction and the experimental results indicates the ICF model is reliable to predict the rheological behaviour of AlSi4Mg2.
Weld Fatigue Life Analysis of Truck Mixer Sub-frame Based on Equivalent Structural Stress Method
Authors: Zhang Kai , Wu Lina , Chen Tao
Published: February 2022

In order to accurately calculate the fatigue life of the sub-frame weld of the mixer truck during the design stage, fatigue analysis of the weld is carried out by equivalent structural stress method. Through the finite element analysis of the frame, the key weld position is researched. By using the inertial release method, the stress response of the frame under the single excitation of the unit load is obtained. Combined with the basic principle of equivalent structural stress, the stress at the weld position is calculated, and the main S-N curve with a survival rate of 50% is selected to predict the fatigue life of the weld. The results show that the fatigue life of the key weld is 105.803 cycles, which fails to reach the design target value. The equivalent structural stress method has the characteristics of grid insensitivity and can better predict the fatigue life of the sub-frame weld of the mixer truck.
Cooling capacity evaluation of passive radiation cooling materials
Authors: Li Tingxuan , Xia Zhilin , Fan Xiaochun
Published: February 2022

passive radiation cooling technology has aroused widespread interest and research enthusiasm because it can cool objects with zero energy consumption, and even cool to below the ambient temperature. At present, when evaluating the cooling performance of radiation cooling materials, in order to reduce the impact of air convection heat transfer and improve the radiation cooling capacity of materials, test samples are usually put into incubators for insulation. In this paper, the finite element method was used to analyze the influence of the size and material of the common used structural incubator on the radiation cooling capacity of the test sample, as well as the influence of the selection of reference ambient temperature. Results show that the selection of incubator structure, material and ambient temperature has a obvious impact on the evaluation results of material radiation cooling capacity, especially when the ambient heat convection coefficient is low. Therefore, for comparing the test results of different research work, a unified incubator design is needed, including structural size and material selection.
Study on Dynamic Pore Water Scouring of Asphalt Pavement by Mesoscopic Simulation Method
Authors: Xie Shuzhi , Li Yongpeng , Lu Weipeng , Pu Na , Sun Mingzhi
Published: February 2022

Dynamic water scouring caused by high-speed wheel load is an important cause of asphalt pavement water damage, which seriously affects the service life of asphalt pavement. In this paper, the dynamic water scouring simulation calculation model of asphalt pavement was established by mesoscopic level. Through the simulation model, the water scouring phenomenon of saturated and unsaturated pore in pavement caused by high-speed wheel load was discussed and studied, which mainly considered the influence of wheel speed, pore diameter, pore saturation state and other factors. The main conclusions are as follows: The water pressure, velocity and shear force in the pore are positively correlated with the wheel load velocity in both saturated and unsaturated states. The internal water pressure and fluid velocity of large pore are slightly lower than those of small pore, and the smaller the pore size is, the greater the vacuum negative pressure is. In the unsaturated state, the turbulent kinetic energy in the pore is an order of magnitude larger than that of saturated state, and the larger the pore is, the greater the turbulent kinetic energy is, so the water erosion damage of gas-liquid two-phase flowing is more serious than the saturated state.
The nitrogen footprints of China’s major urban agglomerations: understanding regional challenges to advance sustainable development
Authors: Xian Chaofan , Wu Tong , Lu Fei , Zhang Jingjing , Gong Cheng , Ouyang Zhiyun
Published: February 2022

The overgrowth of reactive nitrogen emissions (Nr, all species of nitrogen except N2 gas) is a major cause of environmental pollution, especially in rapidly urbanizing regions. The nitrogen footprint (NF) indicator has been widely used to assess Nr losses occurring from the consumption of food and energy. We undertake the first attempt to apply NF methods to explore the spatial-temporal NF characteristics of major urban agglomerations in China between 2000 and 2019, and find that the highest level of annual NF (average 3868 Gg N yr−1) was produced by the Yangtze River Delta urban agglomeration (YRDUA), followed by the Beijing–Tianjin–Hebei urban agglomeration (BTHUA) (average 2657 Gg N yr−1). Their NF growth rates showed similar downward trends during the study period, while the Pearl River Delta urban agglomeration (PRDUA) (average 1528 Gg N yr−1) retained a higher growth rate. The average proportions of food NF (FNF) in BTHUA, YRDUA and PRDUA were 57.64%, 68.64% and 66.79%, respectively. Compared to the FNF, the energy NF gradually plays a more important role in China’s urban agglomerations compared to other countries. Analysis of the underlying drivers showed that an increasing urbanization rate boosted the NF of YRDUA, and rising GDP per capita significantly contributed to the NF growths of BTHUA and PRDUA. Through scenario analysis, we found that shifting to healthy dietary patterns and a partial substitution of fossil fuels with clean energy, as well as improvements in rural wastewater treatment, could contribute to NF reductions by 2030. The largest potential NF reduction is predicted in PRDUA (29% reduction), followed by YRDUA (23% reduction) and BTHUA (18% reduction). The energy reduction scenario is considered to be the most realistic in reducing the NF. We demonstrate the potential of the NF as a tool for the assessment of sustainable development in urban agglomeration, which may prove instructive for broader research on sustainable Nr management.