bluuebunny/crossref_metadata_2025 huggingface dataset:
Circular electromechanical resonators based on hexagonal-boron nitride-graphene heterostructures
Authors: Kumar Rohit , Session Deric W. , Tsuchikawa Ryuichi , Homer Mario , Paas Harrison , Watanabe Kenji , Taniguchi Takashi , Deshpande Vikram V.
Published: November 2020

2D materials such as graphene and hexagonal-boron nitride (h-BN), to name a few, when layered on top of each other offer a class of metamaterials with interesting properties. For example, the twisting degree of freedom between two layers has started the field of twistronics. The exceptional attributes of 2D materials like ultra-low mass, robustness, and high tunability make them very suitable for nanoelectromechanical systems (NEMS). Yet the mechanical properties of these heterostructures in the form of NEMS have not been studied extensively. Such 2D NEMS hold promise for various technological applications, namely, ultrafast sensors, actuators, etc. We report fabrication and characterization of h-BN graphene heterostructure-based circular nanoelectromechanical resonators on sapphire substrates. The devices are measured at cryogenic temperatures and exhibit multiple mode frequencies, which are highly tunable with gate voltage. A continuum mechanics model is employed to analyze the transmission (S21) data of the fundamental mode. Parameters like built-in tension obtained from the fit are used to identify the indices (m, n) of higher mechanical modes observed for the device, providing further device characterization. Such 2D NEMS could offer a way to study diverse electronic phenomena such as superconductivity in twisted bilayer graphene (tBLG) heterostructures.
Flow dynamics and azimuthal behavior of the self-excited acoustic modes in axisymmetric shallow cavities
Authors: Abdelmwgoud Moamenbellah , Shaaban Mahmoud , Mohany Atef
Published: November 2020

Self-excitation of acoustic resonance in axisymmetric cavities can lead to a complex flow–acoustic coupling, which may result in severe noise generation. In this work, a large eddy simulation is performed to model the different flow–sound coupling mechanisms during the self-excitation of various excitable acoustic modes in an axisymmetric shallow cavity configuration with an aspect ratio of L/d = 1 over the lock-in region. The compressible Navier–Stokes equations are solved at a resolution sufficient to capture the flow and the acoustic dynamics. The excitation of three acoustic modes of different aerodynamic characteristics over the range of the tested flow velocities was observed. These modes are a stationary diametral mode, a spinning diametral mode, and a longitudinal mode. The initiation and separation of vortices over the cavity mouth accompanying the self-excitation of each mode involve different dynamics. If two antisymmetric series of vortical crescents separate successively at the leading edge, a stationary acoustic mode is excited. The formation of a continuously rotating helical vortex, connecting the leading edge and the trailing edge, leads to the excitation of the diametral spinning mode. The excitation of the longitudinal mode is associated with symmetric rings of vortices. Complex patterns of flow velocities and Reynolds stresses in the circumferential direction are observed for the diametral modes but not for the longitudinal mode. In all cases, the excitation of acoustic resonance requires a synchronization of the vortex separation and impingement processes, which is necessary for efficient feedback to sustain the flow–sound coupling mechanism.
Fiber-integrated microcavities for efficient generation of coherent acoustic phonons
Authors: Ortiz O. , Pastier F. , Rodriguez A. , Priya  , Lemaitre A. , Gomez-Carbonell C. , Sagnes I. , Harouri A. , Senellart P. , Giesz V. , Esmann M. , Lanzillotti-Kimura N. D.
Published: November 2020

Coherent phonon generation by optical pump-probe experiments has enabled the study of acoustic properties at the nanoscale in planar heterostructures, plasmonic resonators, micropillars, and nanowires. Focalizing both the pump and the probe on the same spot of the sample is a critical part of pump-probe experiments. This is particularly relevant in the case of small objects. The main practical challenges for the actual implementation of this technique are stability of the spatiotemporal overlap, reproducibility of the focalization, and optical mode matching conditions. In this work, we solve these three challenges for the case of planar and micropillar optophononic cavities. We integrate the studied samples to single mode fibers lifting the need for focusing optics to excite and detect coherent acoustic phonons. The resulting reflectivity contrast of at least 66% achieved in our samples allows us to observe stable coherent phonon signals over at least a full day and signals at an extremely low excitation power of 1 μW. The monolithic sample structure is transportable and could provide a means to perform reproducible plug-and-play experiments.
Effects of long-term cattle market conditions on continuous season-long and rotational grazing system revenues
Authors: Windh J. L. , Ritten J. P. , Derner J. D. , Paisley S. , Lee B.
Published: November 2020

In this study we evaluated the combination of long-term market conditions and the price slide in the cattle market on revenues associated with continuous and rotational grazing systems. A price slide is a market phenomenon in which lighter cattle sell at a higher price per unit of liveweight compared with their heavier counterparts. We used actual herd average starting and ending weights in this market analysis, and analysed the outcome using five years’ data from a continuous and rotational comparative grazing study. Despite consistently lower weight gains with rotational grazing, differences in gross revenues per steer between grazing treatments ranged from US$43.46 to minus $5.72 across the study years. We observed annual differences in the net returns across years between the two grazing systems; net returns were greater for steers in the continuous grazing treatment in three of the five years, one year with net returns that did not differ between systems, and one year in which net returns were lower with continuous grazing. These variable results showcase the complexity in having both differences in end of grazing season weight classes between the grazing systems and the differential effects of price slide among weight classes. Therefore, we argue that it may be a better management strategy for land managers to determine the optimal ending weights and the time of year to market livestock to meet the goals of an operation, rather than trying to determine which grazing system is ‘best’.
Dietary overlap between cattle and chital in the Queensland dry tropics
Authors: Watter Kurt , Baxter Greg S. , Pople Anthony , Murray Peter J.
Published: November 2020

Chital deer (Axis axis) are an ungulate species introduced to northern Queensland, Australia, in an environment where land is managed for large scale cattle production. Rainfall and pasture growth are markedly seasonal and cattle experience a nutritional shortfall each year before monsoon rain. The presence of chital is perceived by land managers to reduce dry-season grass availability and this study sought to estimate the potential effect of free-living chital on regional cattle production. Diet overlap was greatest during the wet season when both ungulates principally consumed grass, and least during the dry season when chital diet comprised only ~50% grass. Using local estimates for energy values of wet and dry season grass, and the maintenance energy requirements of chital and cattle, we estimated the relative dry-matter seasonal grass intakes of both ungulates. The grass consumed annually by 100 chital could support an additional 25 cattle during the wet season and an additional 14 cattle during the dry season.
Examining the relationship between elections and wildfires
Authors: Kountouris Yiannis
Published: November 2020

This paper examines the relationship between local elections and wildfire. Using data of wildfires in Greek municipalities between 2000 and 2010, I estimate models comparing wildfire outcomes in local election years against non-election years. I find that wildfire occurrence and burned area are systematically lower in the years around local elections. In municipalities where incumbents run for re-election, the decrease in wildfire occurrence is smaller in the years leading to elections, and larger in the years following local elections. There is some limited evidence that the likelihood of re-election influences wildfire outcomes around the time of local elections. The results suggest a relationship can exist between politics at the local level, wildfire occurrence and burned area. As political and economic considerations can be important in driving wildfire outcomes, assessing wildfire risk cannot take place separately from the prevailing political, economic and institutional environment.
Spatial and temporal dynamics of live fuel moisture content in eastern Mediterranean woodlands are driven by an interaction between climate and community structure
Authors: Bar-Massada Avi , Lebrija-Trejos Edwin
Published: November 2020

The initiation and spread of wildfires depend, among others, on the live fuel moisture content (LFMC) in plants. Whereas the intrinsic and environmental drivers of LFMC in individual plants are fairly well understood, less is known about ecological interactions potentially affecting LFMC in diverse plant communities. Here, we asked how the interaction between climate and species diversity affects the spatial and temporal dynamics of LFMC in Mediterranean plant communities. We sampled LFMC in six plant communities located along a steep precipitation gradient in four monthly intervals and analysed how LFMC was affected by the structure of the community as well by site and climate conditions. LFMC varied greatly among species, and climate and species richness had an interactive effect on LFMC. On average, species richness had a strong negative effect on LFMC in sites with high rainfall, whereas in drier sites, richness had a small positive effect. Yet the effect of richness on LFMC varied across species, with some exhibiting a positive effect of richness on their LFMC. Individuals surrounded by more heterospecifics tended to have lower LFMC compared with ones surrounded by conspecifics. Our results highlight the interactive roles of climate and community characteristics on LFMC dynamics in eastern Mediterranean ecosystems.
Variabilité et traitement automatique des langues
Authors: Grezka Aude
Published: November 2020

Par cette contribution, nous souhaitons proposer une analyse de la variation, principalement diatopique, appliquée aux
séquences figées, grâce à une ressource que nous avons développée pour le Traitement Automatique des Langues (TAL). Le grand nombre de
variantes qui apparaissent dans les corpus nous a conduit à effectuer une analyse exhaustive de ces constructions afin de permettre aux
utilisateurs et aux applications TAL, d’utiliser correctement ces séquences figées. Les données textuelles auxquelles
les méthodes et outils du TAL doivent faire face sont variées, volumineuses et de qualités plus ou moins inégales. Enfin, pour accéder au sens des textes, le TAL est confronté aux difficultés que sont les caractéristiques intrinsèques des langues naturelles.
The use of hypocorisms and last names as a stand in for proper names
Authors: Rico Sulayes Antonio
Published: November 2020

The concern about what constitutes a proper name and its components has produced scientific articles in diverse fields from linguistics, to education, to sociology, to medicine. There is also abundant research about the presence of proper names in the repertoire of multiword expressions (MWEs) in different languages. However, there is an absence of studies in the literature that look at the use of a proper name as an MWE where a hypocorism takes the place of the original first name. This study addresses the MWE hypocorism + last name from a comparative perspective and explores its distributional patterns between American English and Mexican Spanish. A statistical analysis reveals that although this type of MWE is present in both languages, the distributional differences between them imply different usage connotations that should be taken into account when communicating in these languages.
Synchronic and diachronic analysis of prepositional multiword modifiers across Romance languages
Authors: Piunno Valentina , Ganfi Vittorio
Published: November 2020

Lexicological and lexicographical studies on multiword expressions in Romance languages have significantly increased in recent years. Even though some attention has been paid to Multiwords functioning as adjectives and adverbs, the structural and the functional relation between them has not been clarified yet.

Employing both a qualitative and quantitative approach, this corpus-based investigation aims at exploring the diatopic distribution and the evolution of Romance multiword lexemes having the form of a prepositional phrase and the function of an adjective or/and an adverb (or both functions). According to data taken from corpora of Latin, Old Italian, Old Spanish and Middle French, this contribution investigates the relationship between the different degrees of schematicity and the productivity of this kind of multiword lexemes in order to highlight the evolutional path and the diachronic/diatopic principles engaged in the multiword modifying system across the different Romance languages taken into consideration.
Compound pendulum pivot force
Authors: Hinrichsen Peter F
Published: November 2020

The force at the pivot of a simple pendulum and the acceleration of the bob have been the subject of a number of papers. The present paper extends this analysis to a compound pendulum, which requires an extra torque to rotate the pendulum about its center of mass. The dependence of the pivot force on κ = k/a, the ratio of the radius of gyration k to the center of mass position a, is investigated. The pivot force on an ideal compound pendulum is shown to be the same as that for a lighter simple pendulum plus a mass located at the pivot.
Bandgap engineering of hydrogenated a-SiC:H thin films for photoelectrochemical water splitting applications
Authors: Mejia María del Carmen , Francisco Sánchez Luis , Rumiche Francisco , Andrés Guerra Jorge
Published: November 2020

Bandgap engineering of a-SiC:H thin films was carried out to assess the material light absorption without compromising its photoelectrochemical water splitting capabilities. The tailoring was performed by varying the hydrogen concentration in the semiconductor and by post-deposition isochronical annealing treatments from 100 °C to 700 °C. Bandgap values were obtained by fitting the fundamental absorption region of the absorption coefficient using three different models. Differences among bandgap values extracted by these methods and its correlation with the a-SiC:H structure, demonstrate that structural features, rather than a hydrogen rearrangement or depletion, would be responsible for annealing induced optical bandgap increment. These features are taking in advantage for the bandgap engineering of a-SiC:H without changing Si-C stoichiometry. Optical bandgap values for p-doped a-SiC:H samples gradually increased from 2.59 to 2.76 eV upon performing each annealing step until 600 °C. Temperature at which an enhancement in the electric performance is observed. We believe, these results will help on the design of monolithic tandem solar cells for water splitting applications.
High-sensitivity mapping of magnetic induction fields with nanometer-scale resolution: comparison of off-axis electron holography and pixelated differential phase contrast
Authors: Boureau Victor , Staňo Michal , Rouvière Jean-Luc , Toussaint Jean-Christophe , Fruchart Olivier , Cooper David
Published: November 2020

We compare two transmission electron microscopy (TEM) based techniques that can provide highly spatially resolved quantitative measurements of magnetic induction fields at high sensitivity. To this end, the magnetic induction of a ferromagnetic NiFe nanowire has been measured and compared to micromagnetic modeling. State-of-the-art off-axis electron holography has been performed using the averaging of large series of holograms to improve the sensitivity of the measurements. These results are then compared to those obtained from pixelated differential phase contrast, a technique that belongs to pixelated (or 4D) scanning transmission electron microscopy (STEM) experiments. This emerging technique uses a pixelated detector to image the local diffraction patterns as the beam is scanned over the sample. For each diffraction pattern, the deflection of the beam is measured and converted into magnetic induction, while scanning the beam allows a map to be generated. Aberration corrected Lorentz (field-free) configurations of the TEM and STEM were used for an improved spatial resolution. We show that the pixelated STEM approach, even when performed using an old generation of charge-coupled device camera, provides better sensitivity at the expense of spatial resolution. A more general comparison of the two quantitative techniques is given.
Yolk-void-shell Si–C nano-particles with tunable void size for high-performance anode of lithium ion batteries
Authors: Zhu Chaoye , Zhang Yao , Ma Zhihong , Wang Hui , Sly Gunnar L
Published: November 2020

Silicon is a promising anode for new-generation lithium ion batteries due to high theoretical lithium storage capacity (4200 mAh g−1). However, the low conductivity and large volumetric expansion hamper the commercialization of the silicon anode. In this case, we present a yolk-void-shell Si–C anode (denoted as Si@Void@C), which is synthesized through nano-Si oxidation, surface carbonization and etching of SiO
x
. The void can be fabricated only by the self-generation and etching of SiO
x
layer on the Si surface, without the help of template materials. Moreover, the void size can be adjusted only by means of the annealing temperature, which can be easily and precisely operated. The Si@Void@C/rGO with void size of 5 nm offers a discharge capacity of 1294 mAh g−1 after 100 cycles at a current density of 500 mA g−1. These enhanced performances can be ascribed to an appropriate size (5 nm) of void space which sufficiently accommodates the silicon volume expansion and stabilizes the carbon shell. At the same time, the voids effectively inhibit the growth of the solid electrolyte interface layer by depressing the decomposition of the electrolyte on the surface of Si in Si@Void@C/rGO. Furthermore, interfaces between Si@Void@C particles and rGO sheets construct bridges for electrons’ conduction. In general, the present work provides a viable strategy for synthesizing silicon–carbon anode materials with long life.
Modification of metal-organic framework composites as trackable carriers with fluorescent and magnetic properties
Authors: Qi Xiaoyue , Chang Ziyong , Fu Guangqin , Chen Tianfeng
Published: November 2020

A fluorescent metal-organic framework (EuMOF) based on Eu3+ nodes coordinated by 1,1′:2′,1″-terphenyl-4,4′,4″,5′-tetracarboxylate (H4ttca) linkers has been developed as a trackable carrier with inherent fluorescence. Since Fe3O4 nanoparticles (NPs) have great value in versatile applications in vivo/vitro including imaging, cell isolation and magnetic responsivity, Fe3O4 NPs were introduced in the EuMOF composites to enhance the multifunctionalities. It has been demonstrated that the Fe3O4 NPs functionalized EuMOF composites have capability for tumor cell retrieval from matrix followed by anti-cancer drug release, which is promising to be developed as an integrated drug screening platform. Cytotoxicity was evaluated and the EuMOF-based nanocomposite exhibits significantly greater (up to 4x) biocompatibility tested on MCF-7 cells than the Zn-based MOF (the same ligand). Moreover, the EuMOF nanocarrier is capable of loading and releasing anti-cancer drugs in a controllable manner, where Doxorubicin (Dox) functionalized as a payload. Controllable release was successfully achieved after incubation with tumor cells and endocytosis analysis was obtained through the fluorescent imaging which offers monitoring of apoptosis after cargo release. Overall, fluorescent/magnetic properties of EuMOF has been investigated systematically, making it easy to be tracked in potential in vivo/vitro applications. As a drug carrier, it is biocompatible and shows highly efficient drug loading within 5 min, holding great promise in potential therapeutic delivery and other clinical applications.
Self-rectifying resistance switching memory based on a dynamic p–n junction
Authors: Wu Changjin , Li Xiaoli , Xu Xiaohong , Lee Bo Wha , Chae Seung Chul , Liu Chunli
Published: November 2020

Although resistance random access memory (RRAM) is considered as one of the most promising next-generation memories, the sneak-path issue is still challenging for the realization of high-density crossbar memory array. The integration of the rectifying effect with resistance switching has been considered feasible to suppress the sneaking current. Herein, we report a self-rectifying resistance switching (SR-RS) by a newly discovered Li ions migration induced dynamic p–n junction at the Li-doped ZnO and ZnO layer interface. The Au/Li–ZnO/ZnO/Pt structure exhibits a forming-free and stable resistance switching with a high resistance ratio of R
OFF/R
ON ∼ 104 and a large rectification ratio ∼106. In the Li–ZnO/ZnO bilayer, the electric field drives the dissociation and recombination of the self-compensated

L

i

Z
n

−

−
L

i

i

+

complex pairs (

L

i

Z
n

−

:

p-type substitutional defect;

L

i

i

+

:

n-type interstitial defect) through the transport of

L

i

i

+

between the two layers, thereby induces the formation of a dynamic p–n junction. Using this structure as a memory stacking device, the maximum crossbar array size has been calculated to be ∼16 Mbit in the worst-case scenario, which confirms the potential of the proposed device structure for the selection-device free and high-density resistance random access memory applications.
Prediction models for pulmonary function during acute exacerbation of chronic obstructive pulmonary disease
Authors: Chen Jing , Yang Zhao , Yuan Qun , Xiong Da-xi , Guo Li-quan
Published: November 2020

Objective:
The pulmonary function test is an effort-dependent test; however, during acute exacerbation of chronic obstructive pulmonary disease (AECOPD), patients are unable to effectively cooperate due to poor health. The present study aimed to establish prediction models that only require demographic and inflammatory parameters to predict pulmonary function indexes: forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Approach: The goal was to establish prediction models based on multi-output support vector regression. A total of 143 subjects received a peripheral blood examination and pulmonary function test. The demographic and inflammatory parameters were used as input features, and FEV1 and FVC were used as the target features in prediction models. Three models (mixed model, severe model and nonsevere model) were established with FEV1 < 1 l as the threshold of severe episodes of AECOPD. The values of FEV1 and FVC from the pulmonary function tests were compared with the prediction models to validate the performances of the developed prediction models. Main results: The severe and nonsevere models’ prediction performances were better than that of the mixed model. The mean squared errors were lower than 0.05 l2, and the decision coefficients (R
2) were higher than 0.40. The two-tailed t-test results showed that for both severe and nonsevere models, the absolute percentage errors of FEV1 and FVC were within 10%. Significance: Our study shows the feasibility of predicting the pulmonary function indexes FEV1 and FVC with demographic and inflammatory parameters when the pulmonary function test fails to be implemented, which is beneficial for the treatment of AECOPD.
Selective tuning of Hilbert spaces in states encoded with spatial modes of light
Authors: Anwar Ali , Lal Nijil , Prabhakar Shashi , Singh R P
Published: November 2020

Spatial modes of light directly give the most easily accessible degree of freedom that span an infinite dimensional Hilbert space. The higher dimensional spatial mode entanglement realized using spontaneous parametric down conversion (SPDC) process is generally restricted to the subspace defined by a single spatial mode in pump. Access to other modal subspaces can be realized by pumping beams carrying several easily tunable transverse modes. As a proof of principle experiment, we generate twin-photon states in an SPDC process with pump as a superposition of first order Laguerre–Gaussian (or Hermite–Gaussian) modes. We show that the generated states can be easily tuned between different subspaces by controlling the respective modal content in the pump superposition.
Power network quality analysis and harmonic control of large electric drive test station
Authors: Dengdong Meng , Wu Wen
Published: November 2020

During the operation of large-scale electric drive test-bed, the driving and loading frequency conversion equipment will produce many different frequency harmonic currents due to their nonlinear characteristics, which will not only affect each other, but also interfere with other transmission and distribution equipment, resulting in current and voltage waveform distortion. In this paper, the operation conditions of a large power drive test bench are analyzed and studied, and the power quality control solution is proposed. The test results prove the effectiveness of the control measures.
Analysis and Verification of Algeria KAE 3MWp Solar Power Plant Electrical Capacity Calculation Report
Authors: Ye Xiang
Published: November 2020

The electrical capacity calculation report of Algeria KAE 3MWp Solar Power Plant is specifically analysized and verified. The analysis results show that the EPC contractual and conceptional design is applicable and further optimization works is possible to be implemented during construction design stage, the technical requirements for both electricity production and PR values are confirmed within efficient ranges.
Parametric Modelling and Seismic Analysis of 220kV Power Distribution Equipment in Electrical Substation
Authors: Liu Wei , Li Sheng , Zhao Mingguan , Lu Zhicheng , Zhang Xiaojun , Fu Guangzhi , Meng Xianzheng
Published: November 2020

Power grid is an important part of the earthquake lifeline project. As electrical substation is the node of the power grid, and the safety evaluation of the substation under earthquakes is essential. There are a wide variety of electrical equipment in substations, and multi pieces of equipment are interconnected to form the complex circuits. Seismic modelling of substation equipment requires engineering researchers to have an accurate understanding of the structure of electrical equipment, as well as to collect complete electrical equipment structural parameters. This process takes a lot of time and effort. This paper proposed a parametric modelling method for substation equipment, which can achieve effectiveness in seismic modelling. Parametric modelling and seismic analysis of high-voltage equipment of a 220 kV substation in Xinjiang is carried out, which verified the validity and applicability of the method.
One-point method for speed strategy optimization based on slope simplification and speed limit prediction
Authors: Han Bing , Xing Jian , Zhong Jikun
Published: November 2020

The automatic driving of trains is an inevitable trend of the modern development of railway transportation, and it is also a necessary requirement for energy conservation and emission reduction. A train automatic driving speed planning scheme with only one operation state transition point in the simplified slope section is proposed based on slope simplification principle and speed limit regulation on an interval line, which reduces the control complexity and energy consumption for automatic driving. An improved fitness function of genetic algorithm (GA) is explored to solve an operation state transition point position of the train, then train energy-saving operation strategy is presented. Practical energy costing experiment for freight train (HXD3) with 2,800 tons for a 33.7km line on Bin-Zhou railway line is obtained and compared with the proposed algorithm. Results show that energy consumption is saved by 15.2% for the speed strategy from the proposed method. So operation strategy is simplified greatly because of only one state transition point in a simplified interval which is more suitable for automatic driving. On the other hand, one point operation strategy is also more energy efficient than manual manipulation. Therefore, the proposed method provides a simple and efficient control strategy for train automatic driving.
Effect of Insulator Bulk Conductivity Non-uniformity on Surface Charge Accumulation
Authors: Zhu Qingdong , Zhu Wenbing , Zhu Mengzhao
Published: November 2020

In order to clarify the effect of insulator bulk conductivity non-uniformity, controlled by electric field, on surface charge accumulation under dc high voltage, a simulation model involving multi-physics, which includes transition from initial capacitive to stationary resistive field, is established. In terms of this, the characters of surface charge accumulation are obtained. It is found that non-uniformity of electric conductivity contributes to the change of surface charge distribution profile, but not to the increase of the maximum surface charge density when the applied voltage is less than 1000 kV. After voltage exceeds 1000 kV, the maximum charge density becomes smaller compared to the case with uniform conductivity. The results indicate that electric conductivity non-uniformity relating to electric field is a source contributing to surface charge accumulation through insulator bulk, and should not be neglected.
Compound Control Scheme Based on Repetitive Controller And Proportional Controller In Building Distribution Grid
Authors: Li Shan-Shou , Wu Yue-Yue , Chao-Zan XU
Published: November 2020

This paper proposes a compound control scheme of three-Phase four-Leg (3P4L) SVG based on the combination of repetitive controller and proportional controller, for the purpose of independently compensating the zero-sequence current under the conditions of load imbalance. To begin with, the overall control scheme of the system is given, in which the repetitive controller and P-controller are connected in parallel. Then, we concluded the recommended scheme is completely equivalent to the series scheme, hence the proportional controller and the repetitive controller can be designed independently. After that, a step-by-step design example of open-loop proportional controller and closed-loop repetitive controller are described. Moreover, the grid voltage feed-forward block is adopted for suppressing the influence of harmonics voltage in grid. Last but not least, Simulation experiments are carried out, and the results demonstrate that the proposed scheme can effectively improve the dynamic performance and stability of 3P4L-SVG under the conditions of load imbalance or grid voltage imbalance.
Balance control of quadruped robot based on model predictive control
Authors: Wu ChengYe , Wei Qing , Zhang Cong , An HongLei
Published: November 2020

Aiming at the steady motion of the quadruped robot during support period of the locomotion, it is necessary to plan the ground reaction force (GRF) of legs. For the control of the plane height of the robot body, we take the standing balance of the simply modelled quadruped robot as the research object, and use the model predictive control algorithm to plan quadruped robot’s GRF of its position and attitude control, and then map the force to the operating space through the Jacobian matrix of the joint space to obtain the torque of the joint space. This paper uses MATLAB and RecurDyn for the co-simulation, and obtains good control results from it. At the end, we analyze the feasibility and rationality of its algorithm application by comparing it with the traditional balance controller. The work above provides the basis for the control and design of the subsequent quadruped robot motion planning.
A new parameter adaptive control of four-dimensional hyperchaotic system
Authors: Liao Xiaokang , Chen Zili , Lin Jianhui
Published: November 2020

By adding a state feedback controller to a three-dimensional chaotic system, a new four-dimensional hyperchaotic autonomous system is constructed. The nonlinear dynamic behavior of the system is deeply investigated, including power spectrum, Poincare cross section, Lyapunov exponential spectrum and bifurcation graph. The analysis shows that the new four-dimensional hyperchaotic system has complex chaotic motions with different parameters, and the related analog chaotic circuits are designed. Finally, a parameter adaptive controller is designed to achieve global stability control of chaotic systems. The effectiveness of the proposed method is verified by numerical simulation.
Application and Analysis of Big Data Technology in Smart Grid
Authors: Wang Shuchun , Sun Xiaoguang , Geng Jianyu , Han Yuan , Zhang Chunyong , Zhang Weihua
Published: November 2020

In order to make the modern power system more intelligent, various data acquisition equipment and information management systems are required, such as smart meters, remote terminal units (RTU), phasor measurement units(PMU), power distribution management systems(DMS), and energy management systems(EMS), customer management system(CMS), power generation management system(GMS) have been widely installed. These systems create large amounts of data, which is the main source of smart grid big data. Researching advanced data analysis technology is the most urgent task for the development of smart grid. It can make the best decision for the control and operation of the grid, and can improve the flexibility, safety, reliability and efficiency of the power system. This article analyses the cause of smart grid big data and the importance of data analysis, and discusses the development trend of big data technology. Selectively analysed the source and type of smart grid big data, summarized the characteristics of smart grid big data, gave various application scenarios, and introduced the smart grid big data analysis platform and the functions being developed.
Research on Voltage Control of Multi Terminal Flexible Medium Voltage DC Distribution Network
Authors: Yang Xiaoping , Xiao Feng
Published: November 2020

In order to solve the problem that the original control strategy cannot meet the voltage quality requirements of the system under various operation modes due to the expansion of DC distribution network scale, this paper studies the voltage control strategy of a ring type medium voltage DC distribution network. Firstly, the traditional control method is improved, the droop control is added to the margin control as the slave station control method. At the same time, the DC transformer connected with the energy storage is used as the backup voltage regulating station in case of power shortage to meet the voltage quality requirements of the system in normal operation and fault. Then, a DC voltage control strategy based on depth first search is proposed to solve the problem of voltage deviation caused by system fault, so that the distribution network can automatically adjust the control according to the real-time structure in case of fault and improve the voltage quality. Finally, the proposed control strategy is simulated in PSCAD / EMTDC to verify the effectiveness of the control strategy.
Optimal capacity allocation of thermal storage system considering peak regulation ancillary services
Authors: Zhang Tao , Zhao Guanxiong , Wang Shuwen , Wang Shunjiang , Li Yang
Published: November 2020

Limited by the operation mode of ‘heat-set’ is one of the main reasons for the large amount of wind abandonment in Northeast China. Reasonable allocation of electric heat storage system is an effective means to improve the wind power absorption capacity of regional power grid. In this paper, an optimal capacity allocation model of electric heat storage system considering peak regulation auxiliary services is proposed, and the optimal capacity of electric heat storage system is solved based on game theory. Firstly, the economic benefits of each stakeholder participating in peak regulation ancillary service market are analyzed by allocating electric heat storage equipment in thermal power plants. Secondly, a bi-level programming model for optimal capacity allocation of electric thermal storage system is established. Finally, the model is optimized by particle swarm optimization and Cplex hybrid optimization method. The optimal configuration scheme of the electric heat storage system is obtained by solving the optimization problem. The example shows that the model is reasonable and effective.
Clearing approach for day-ahead electricity spot market based on fast calibration of conditional section constraints
Authors: Wu Yang , Li Xiufeng , Jiang Yan , Gao Daochun , Duan Ruiqin , Zhao Zhenyu , Yin Ziheng , Sun Yujun
Published: November 2020

With the expansion of the pilot area of the electricity spot market in China, how to consider the conditional section to clear the spot market is a new problem faced by dispatching operators. This paper first analyses the impact of conditional section constraints on the clearing of the spot market. Secondly, in order to improve the efficiency of spot market clearing calculation, based on the mode of posterior addition, a fast method of checking condition section is proposed. Thirdly, this method is incorporated into the framework of day-ahead spot market clearing. Finally, the validity of the method is verified by an example analysis of the IEEE118-node system.
Optimal Planning Method of Distribution Transformer Network for Seasonal Load
Authors: Wang Zhanwei , Chen Haidong , Deng Shiyu , Wu Jian , Li Demin , Li Jiwei , Xie Yan
Published: November 2020

Taking into account the reliability of power supply, this paper proposes an optimal planning method for distribution transformer network adapting to seasonal load in order to improve the low efficiency of equipment utilization in rural coal-to-electricity conversion areas. In this method, a bi-level programming model of distribution transformer network is constructed to minimize the overall cost. Voronoi is used to plan the distribution transformer at the upper level, Prim algorithm is used to plan the low-voltage power supply line at the lower level, and genetic algorithm is used to optimize the solution (seek the optimal solution). Finally, the feasibility of this method is verified by the planning of distribution transformer in typical power supply areas. The analysis of examples shows that the distribution transformer loss can be reduced by establishing the low-voltage tie-line between distribution transformers and the transformation of operation mode, which also provides the basis for the load transfer under the low-voltage line fault.
Construction of a value-based equipment development decision analysis index system
Authors: Wang Na , Li Kaiyan , Xue Fengtong , Gong Maohua
Published: November 2020

This article summarizes the feasibility and related achievements of the value-focused thinking in the field of equipment development. On this basis, in response to previous equipment development decisions that mainly considered combat effectiveness, this paper analyzes equipment development decision-making issues from the two dimensions of mission and resource constraints from the perspective of value, constructs a decision value model, and sets a scoring function for it, Using the final value score as the basis for the selection of equipment plans, aiming to provide a method reference for the decision-making of China’s equipment construction plans.
Subsynchronous oscillation mitigation strategy based on adaptive band-stop filter in DFIG-based wind farms
Authors: Yang Hongyu , Xu Shanshan , Wu Xi , Gu Wen , Mei Rui , Lyu Wan
Published: November 2020

Subsynchronous Oscillation (SSO) may exist in doubly-fed induction generator (DFIG)-based wind farms connected with a series compensated transmission network, also called subsynchronous control interaction (SSCI). Different from thermal power units, the SSO frequency of wind farm varies with the change of system operating conditions, and has the characteristic of time-varying. When the operating conditions change, the existing mitigation strategies may lose the effect. To address this issue, a SSO mitigation strategy based on adaptive band-stop filter (ABSF) is proposed in this paper: When SSO occurs in the system, the ABSF parameter is adjusted according to the oscillation frequency measured by PASTd algorithm to filter out the subsynchronous component in the RSC loop effectively, so as to break the generation path of SSO and suppress SSO. Compared with the existing mitigation strategies, the proposed strategy doesn’t need the mathematical model of the system, and can ensure strong robustness under various operating conditions. Finally, the effectiveness and robustness of the proposed strategy are verified on the Matlab/Simulink.
Analysis of Factors Affecting Temperature Rise of Oil-immersed Power Transformer
Authors: Sun Cheng-chao , Xiao Chi , Hou Jun , Kong Liang , Ye Jian , Yu Wen-jian
Published: November 2020

The key factors that affect the operation state of power transformer include thermal problem and insulation problem. It is of great significance to pay attention to the factors affecting the temperature rise characteristics of transformer to ensure its stable operation. The temperature rise characteristic model of transformer is established to explore the possibility of replacing mineral oil with plant insulation oil FR3 in this paper. On the basis of calculating the influence of ambient temperature change of external heat source on transformer temperature rise, the relative life loss rate of transformer under different ambient temperature is calculated. The results show that FR3 vegetable oil can replace mineral oil in terms of temperature rise. The temperature of the transformer core and winding hot spot increases with the ambient temperature. When the ambient temperature exceeds 293K, the relative life loss rate of the transformer increases very quickly. Therefore, the transformer should not be kept in an environment where the temperature exceeds 293K for a long time.
Effect of pretreatment on the microstructure of multiwalled carbon nanotubes
Authors: He X L , Tang P J , Wang X Y , Li P Y
Published: November 2020

Four kinds of multi-walled carbon nanotubes pretreated by different methods were studied. Chemically functionalized (hydroxylation and carboxylation) CNTs were prepared by oxidizing original CNTs in H2SO4 solutions of different temperatures and concentrations by KMnO4. Graphitized CNTs were prepared by heat-treating original CNTs in an inert gas at 2800°C for 20 hours. CNTs Nickel plating on the surface was obtained by electroless plating. The effect of pretreatment on the surface state and microstructure of carbon nanotubes was also studied. The results showed that Chemical functionalization could form some functional groups on the surface of CNTs, which could not only improve the compatibility of CNTs with some solvents, but also purified CNTs, which had a positive effect on the preparation of composite materials. High-temperature graphitization treatment could significantly increase the degree of crystallization of carbon nanotubes and reduce structural defects. After electroless nickel plating, evenly distributed nano-sized metal particles were formed on the surface of the CNTs, and the interface between the two was well bonded.
Environmental technology for processing waste from mining and processing plants
Authors: Bobkov Vladimir , Meshalkin Valery , Aristov Vitaly , Dli Maxim
Published: November 2020

This research proposes a system approach for the analysis of volumes, physicochemical, granulometric, lithologic and thermal characteristics of waste from ore-dressing and processing enterprises stored in the dumps (tailing dumps) of ore-dressing and processing plants to assess the economic potential of its use in the system of complex power and resource efficient environmentally safe processing including palletizing machines, conveyor indurating machines and ore–thermal furnaces. The obtained results allow the authors to formulate the basic engineering, technological, economic and environmental requirements for complex chemical and power engineering systems of processing technogenic waste from ore-dressing and processing plants, these results make it also possible to define the degree of variability for the characteristics of the waste lots from various dumps. The paper describes the developed intensional and mathematical formulations for the multiscale problem of optimizing chemical and power engineering processes of technogenic raw materials processing in a complex chemical and power engineering system as a problem for discrete dynamic programming. The distinctive feature of this problem is to take into account the spatio-temporal multistage processing in a moving multilayer mass of pelletized raw material, the intensity of the process of internal moisture transfer and the variables for the control flow of the heat carrier gas.
Isolation of Dalmatian chamomile extracts - environmentally friendly natural compounds with insecticidal action
Authors: Mukovoz Petr , Mukovoz Vladimir , Dankovtseva Ekaterina
Published: November 2020

Extracts of Dalmatian chamomile (Pyrethrum cinerariaefolium Trev) grown in the greenhouse complex of the Institute of Phytopathology were obtained. The resulting extracts were isolated from the dried inflorescences of this plant, by an initial stepwise extraction of lipid fractions with a mixture of dichloroethane / petroleum ether, methanol and a mixture of methanol / petroleum ether, followed by purification on activated carbon. By further separation of the obtained extracts by preparative column chromatography, biologically active fractions with different contents of natural insecticides from the pyrethrin group were isolated. The content of biologically active components in various fractions was determined by the methods of chromatomass-spectrometry. It was found that low-polarity eluents (hexane / chloroform) recover pyrethrin I, cinerin I, and jasmolin I most fully, and the maximum recovery of pyrethrin II and cinerin II is observed when using relatively polar eluents (hexane / acetone). The insecticidal effect of the end products on the great cereal aphid (Sitobion avenae) was studied. It was found that the maximum insecticidal effect (100% mortality of insects) was exhibited by the pyrethrine fraction isolated during extraction with low-polarity eluents (hexane / chloroform). It was found that the pyrethrine fraction isolated during extraction with relatively polar eluents (hexane / acetone) exhibited a moderate insecticidal effect (77–81% of insect mortality). It has been shown that Dalmatian chamomile extracts have a high insecticidal effect against such a pest of cereal crops as the large cereal aphid and can be successfully used as effective, environmentally friendly natural insecticides, including in the form of biologically active additives to commercial insecticidal preparations.
Search for approaches to producing organic fertilizers from raw materials of plant and animal origin
Authors: Valiullin Lenar , Titova Valentina , Tremasov Yurii , Huzin Damir , Nabatov Alexey , Validov Shamil , Bogun Inna , Cheremisin Alexey , Kudeyarov Valery
Published: November 2020

Due to the annual increase in emissions of animal and poultry waste into the environment, scientists around the world are increasingly interested in improving technologies to accelerate the processing of agricultural waste. In the presented work, 6 microorganisms were selected: Lactobacillus spp., thermophilic bacteria (Bac. subtilis), Clostridium spp., Penicililum spp., Saccharomyces cerevisiae, Micrococcus nishomyaensis) to accelerate the processing of animal waste. The toxicity and toxigenicity of newly isolated strains of microorganisms was assessed. At the same time, it was found that the strains of microorganisms do not have toxicity and toxigenicity.