bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic and Static Comparative Analysis on the Cost-Profit of Backyard Hog Production and Scale Hog Production in China
Authors: Jia Xiaojuan , Li Jianqiang
Published: January 2021

This paper uses a combination of dynamic comparison and static comparison to comprehensively compare the cost-profit changes and gaps between backyard hog production and small, medium and large scale production from 2007 to 2018 in China, and discusses the relationship between the cost-profit of hog production and production scales. The purpose is to provide data basis and support for the government to formulate relevant policies, and to provide reference for the transformation of farmers’ hog production behavior, so as to further promote the healthy and stable development of the pig industry. The results showed that: (1) the cost of backyard hog production is the highest, and the cost of large-scale production is the lowest, and the cost is inversely proportional to the scale of production; (2) the main incentives for the high cost of backyard hog production are the input of piglets, feed and labor, and The main incentives for the high cost of scale hog production are the input of piglets and feed. Scale hog production saves labor costs more than backyard hog production; (3) The net profit of backyard hog production is the lowest, and the net profit of medium-scale production is the highest. It is not that the larger the scale, the higher the profit; (4) The profit gap between backyard hog production and scale hog production is gradually expanding, and the economic advantages of scale hog production are obvious. Therefore, it is necessary to improve the production technology service system, develop moderately scale production, and improve the level of organization of farmers in order to promote the modernization and transformation of backyard hog production and further enhance the competitiveness of China’s pig industry.
Safety Prediction of Deep Foundation Pit Based on Neural Network and Entropy Fuzzy Evaluation
Authors: Xiudong Xie , Caizhen Pan
Published: January 2021

The monitoring data can effectively reflect the safety status of the project during the construction of deep foundation pit, and the risks existing in the project can be discovered in time and the development trend can be reasonably predicted through the processing and analysis of the existing monitoring data. In this paper, a deep foundation pit in compound soil area of a coastal city was taken as an example, the BP neural network was taken to predict the monitoring data in the next stage, the entropy method was utilized to determine the weight of the evaluation index according to the predicted value, and the fuzzy comprehensive evaluation method was used to quantitatively describe the future safety status, so as to formulate targeted countermeasures and improve the construction safety.
Study on large deformation characteristics and control technology of tunnel surrounding rock in debris flow accumulation area
Authors: Lin Mu-shui , Zhang Cheng-ke , Wu Rong-jun , Qiu Fu-sheng , Li Ning , Chen Li , Guo Hao-sen
Published: January 2021

Debris flow accumulation has the characteristics of loose and broken, low strength, poor stability and so on. When the tunnel passes through the debris flow accumulation area, it is easy to bring major safety hazards to the construction site. Based on the engineering background of Gangou tunnel crossing debris flow accumulation area in the fourth bid of Jiumian expressway, this paper establishes a numerical calculation model, studies the large deformation characteristics of tunnel surrounding rock in debris flow area, determines the reasonable reinforcement range of tunnel surrounding rock, and puts forward the comprehensive control technology of tunnel passing through debris flow accumulation body combining surface stability and underground reinforcement based on simulation results and field experience. The numerical results show that the deformation of surrounding rock and ground surface can be effectively controlled. The rationality of the proposed control measures is verified by field monitoring, which provides a reference for surrounding rock control of tunnel under type conditions.
Study on static load test of modified and extended rigid frame bridge
Authors: Yu-feng NING , Qing-cheng YANG , Wei-wei SUN , Shun-chao CHEN
Published: January 2021

In order to evaluate the mechanical condition and working performance of a rigid frame bridge after reconstruction and extension, the mechanical performance of the bridge was analyzed by static load test. Static load test is the test of stress at each section of main beam under the action of partial load and medium load. The results show that, under the action of each load, the check coefficient of strain and deflection at each measuring point of the box girder does not exceed the standard limit value 1, the relative residual strain or deformation at each measuring point does not exceed the standard limit value 20%, the stress condition of the tested section of the box girder is normal, and the structure is under the normal stress state under the action of the test load.
Study on the flexural performance of RC beams anchored with CFRP plates under secondary load
Authors: Feng Xiangrui , Cui Xian , Luo Haikun
Published: January 2021

In order to explore the influence of length and width of CFRP as well as anchor spacing on the reinforcement effectiveness of CFRP plates on reinforcement concrete beams (RC beams) under secondary load, 7 anchored damaged FRP reinforced concrete beams are used as test beams, 1 unanchored beam is used as a control beam, and structural indicators such as ultimate load and bending strength are analyzed in the result. The conclusion is that composite CFRP plate can effectively prevent the early peeling and failure of carbon plates and improve the ultimate bearing capacity of the beam. When the width of the CFRP plate decreases, the thickness increases and the steel plate anchor spacing increases appropriately, the ultimate bearing capacity and ductility of the beam are significantly improved.
Research on Mechanical Properties of Angle Beam-column Joint with Gusset plate
Authors: Li Yunan , Dong Xian , Wang Zhan , Li Jiajun , Qin Ke
Published: January 2021

There is wide use of beam-column joint with gusset plate angle connection in engineering, however, the mechanical properties of these joints are still lack of complete theoretical and experimental research. This kind of joint is often simplified as an articulated connection or other types of connections in the design. In this paper, experimental study and finite element analysis are carried out to study the flexural behavior of the beam-column joint with gusset plate angle connection. The finite element analysis is used to analyze the differences between the beam-column joint with gusset plate and other joints. The moments-rotation curves and failure modes of the three kinds of beam-column joints were obtained by the static test which were carried out. A more reasonable design of beam-column joint with angle plate of gusset plate is put forward through the research of this paper: the deformation of the column flange is restricted after adding the stiffener, which can avoid the premature yield of the column flange and making the joint have good energy dissipation capacity.
Analysis free surface of nonlinear seepage using the MQRBF method
Authors: SU Yan , SU Yan , ZHENG Zhi-ming , GU Cheng-yu , ZHANG Long-teng
Published: January 2021

In order to solve the characteristics of low accuracy and slow efficiency in traditional numerical solution the free surface problem, the multiquardatic radial base function collocation method(MQ RBF) is used to analyze the constant seepage and unsteady seepage of the homogeneous earth dam. Computation of transient problem of free surface of earth dam by the linear derivation of Richards equation. The results show that the calculation accuracy of the MQRBF is higher than that of the traditional numerical method. The solution process does not involve numerical integral calculation and grid reorganization, which greatly reduces the calculation amount. Compared with the Trefftz method, it has the advantage of solving boundary values and internal values at the same time. It is not limited by the solution of the Laplace equation, and its application is wider and simpler.
Practices of Hydro-Meteorological Support During Construction Period of Largehydropower Project
Authors: Hui CAO , Jishun ZHANG , Zhingming LIANG , Yang XU , Biqiong WU
Published: January 2021

The hydrological and meteorological hydro-meteorological support is one important part of the hydropower construction. Accidents caused by flood and rainstorm during construction will be reduced effectively with the help of reliable hydrological and meteorological forecast which also provides critical technical support for flood prevention and construction organization of projects under construction. Based on the practice of the hydro-meteorological support during the construction period of Three Gorges and Jinsha River cascade hydropower station, this article discussed the methods to support and serve hydro meteorology of large-scale cascade hydropower station construction. Meanwhile, this paper also builds up a hydro-meteorology supportive system for hydro-power station under construction which is led by a hydropower development company and associated by local professional institutions. And this research can also be utilized as a reference for other large-scale hydro-power station construction and to support the hydro-meteorology safeguard during the operation period.
Mercury Content Transported from Atmosphere and Land to Jiaozhou Bay
Authors: Yang Dongfang , Li Haixia , Jing Dongmei , Tian Mingjing , Zhang Longlei
Published: January 2021

According to the data of May, August and October 1992, the range of Hg content in Jiaozhou Bay waters was 0.009-0.050 μg /L, which met the water quality standard of class I sea water. This showed that in terms of Hg content, in May, August and October, the water of Jiaozhou Bay was clean and free from any Hg pollution. In May, the range of Hg content in Jiaozhou Bay waters was 0.009-0.038 μg /L. In August, the range of Hg content in Jiaozhou Bay waters was 0.021-0.050 μg/L. In October, the range of Hg content in Jiaozhou Bay waters was 0.011-0.040 μg /L. There were two sources of Hg content in Jiaozhou Bay waters, surface runoff and atmospheric deposition. The Hg content from surface runoffwas 0.038-0.040 μg /L, and that from atmospheric deposition was 0.050 μg /L. The model diagram was established to show the different paths and contents of Hg content in the process of input into Jiaozhou Bay. In May and October, the surface runoff was not polluted by any Hg content. In August, atmospheric deposition was not contaminated by any Hg content. That revealed that Hg, humans issued to land and atmosphere, finally got to the ocean. There were two paths. One is that human beings discharge Hg into the atmosphere, and the Hg content reached into the ocean through atmospheric sedimentation. The Hg content from atmospheric sedimentation was relatively high, but the transportation time was relatively short. The other is that human beings discharge Hg content to the land. Through surface runoff, the Hg content reached into the ocean, and the Hg content from surface runoff was relatively low, but the transportation time was relatively short. With more and more paths, Hg content was decreasing.
Analysis of Effective Optimization of Construction Technology in Municipal Engineering Construction Projects
Authors: Shasha Dai
Published: January 2021

Municipal engineering construction is related to people’s living standards and environment. To improve the quality of municipal engineering construction projects, it is necessary to strengthen the management and effectively optimize construction technology, and improve the construction efficiency and quality. Based on this, this article will analyze the significance of optimizing construction technology in municipal engineering construction projects, and propose construction technology optimization strategies to improve the level of municipal engineering construction in China.
Dynamic characteristics of pumped storage unit based on the full-size converter
Authors: Wang He , Ma Zhijie
Published: January 2021

For enhancing the regulation performance and the efficient operation of the pumped storage power plant, this paper proposed to combine a hydro-generator set with a full-size converter to achieve the decoupling control of the machine and the power grid. On the basis of the model test, the regulation characteristics of a certain pump-turbine had been discussed and the implication for the converter was highlighted. At the same time, modeling and control for the machine side converter were presented, the simulation results showed that the hydroelectric generator system based on a full-size converter could track the torque change properly through the control system and achieve variable-speed operation due to the decoupling from the fixed grid frequency. The analysis revealed that it is possible to operate the plant beneficially by adopting a full-size converter between the generator motor and the power grid to improve the dynamic performance of the system effectively.
Study on the Spatial Form of Marginal Space of the Street and Crowd Behavior -Take Tanhualin Historic District as an example
Authors: Pei Shunzhe
Published: January 2021

While people tend to overlook marginal space, it is the most important space for communication and integration. This paper took the historic districts of Tanhualin as the subject to explore the spatial elements, spatial characteristics and crowd behaviors of different types of marginal space from the perspective of typology. Based on the number of active users and the space utilization rate, we evaluated the marginal space using image data analysis. This paper explored the design of marginal space, providing references on the rational development of marginal space of urban blocks and improvement of marginal space.
Application of intelligent position and attitude adjustment technology in AIT of the space optical remote sensor
Authors: Zhang Zhifei , Ji Yi , Jiao Wenchun
Published: January 2021

In this paper, we present an intelligent position and attitude adjustment technology to solve the problem that the traditional pose adjustment scheme cannot meet the requirements of AIT, which is one of the most important parts in the manufacture of space optical remote sensor. The problem we have outlined deals largely with the study of a pioneer proposed hybrid pose adjustment strategy and a reanalysed the function of spatial pose adjustment. The strategy is realized as an intelligent position and attitude adjustment platform, and its mechanical analysis and practical statistics in AIT are carried out. The results prove to be encouraging, and it shows that the stiffness of the platform meets the requirements, the complexity of manufacturing the remote sensor is reduced, the total time of a single mission is reduced by nearly 18 times, the total man-time is reduced by 21 times, and the work efficiency is increased by 44 times. This work has resulted in a solution of the manufacturing efficiency and intelligent level of the space optical remote sensor be effectively improved.
Design and development of anchoring positioning control system for riprap leveling ship
Authors: Hua Xiaotao , Liu Yan , Sun Haiyang , Chen Jianru
Published: January 2021

It is very important to level foundation bed by riprap in water and soil engineering. In this paper, a real-time feedback convergence control method is proposed to control the position and heading angle of the riprap leveling ship. The wind, wave, current and hydrodynamic parameters are obtained by empirical formula; the tension of four cables is calculated according to the balance equation of six degrees of freedom, and then the cable deformation is obtained. According to the deformation of the cable, the length of the cable in a certain equilibrium state can be obtained. The length of four cables can be lengthened or shortened by comparing the length of cables at two balanced positions. The length of cables can be controlled by winch to complete the anchoring and positioning control of leveling ship.
Analysis of Buckling Characteristics and Parameter Influence of Composite Thin-walled Lenticular Boom Structures
Authors: Yao Zhichao , Li Dongxu , Zhu Shiyao , Zhou Lilin
Published: January 2021

The stretchable composite thin-walled lenticular boom can be used in the unfolding process of a large spacecraft structure, and its buckling characteristic is one of the focuses of structural design. In this paper, firstly, the critical buckling load formula is derived based on Euler’s formula and laminated theory for the axial compression buckling problem of the lenticular boom, and verified by the finite element method. Secondly, the influence law of the lenticular boom section and layer parameters on the critical buckling load is quantitatively analyzed. The results show that the lenticular boom generally undergoes first-order buckling in the outer direction of the symmetrical bonding surface. The critical buckling load is most significantly affected by the radius of the convex arc, followed by the center ordinate of the convex arc, the thickness of the layer, and the angle of the layer. And these parameters are positively related to the critical buckling load. The radius of the concave arc and the length of the straight section have little effect on the critical buckling load. The research methods and conclusions of this paper can provide reference for the engineering design of the lenticular boom structure.
Roof Snow Removal Device Based on Visual Sensing Technology
Authors: Zhang Zhiyang
Published: January 2021

Based on the analysis of the current situation of roof snow removal technology at home and abroad, this paper proposes a fully automatic roof snow removal device based on visual sensing technology. This product is composed of five functional modules: cutting snow removal module, frozen snow assisting removal module, pulley block anti-drop module, worm gear transmission module, and crawler movement module. Through the cooperation of various mechanisms, the efficient removal of snow on the roof is realized. Automatic removal can effectively reduce the adverse impact of snow on the roof on residents’ lives and economic development.
Influence of radial clearance on nonlinear dynamics of a two-span three-support rotor system
Authors: Xing HE , Yi-ming WU , Mo LI , Fan ZENG
Published: January 2021

Aiming at the structural form of a certain rotor system, a double-span three-support rotor system model is established. It is supported by three rolling bearings and has a typical nonlinear characteristic. The fourth-order Runge-Kutta method is used to solve the differential equations and analyze the nonlinear dynamic characteristics of the rotor system when the radial clearance of the bearing changed. The research results: with the increase of the rear bearing radial clearance, the rotor system performs single cycle, periodic two and pseudo-periodic motion. With the three location bearing radial clearance increases, the rotor system performs single cycle, periodic two and periodic four motion. When the radial clearance is bigger, the rotor system performs two periodic motion. The influence law of radial clearance on double span three - braced rotor system is shown.
FCB system analysis and performance test results of 1000MW ultra supercritical coal fired power station
Authors: Shuying Zhang , Lin Li , Cuihua Zhang , Yan Gao , Tao Luan
Published: January 2021

Fast cut back (FCB) function can make the power station restore the external power supply in a very short period of time from the auxiliary power operation conditions through self-help mode. In case of large-scale power grid failure, FCB further ensures the safety of the main equipments and bring great benefits for the rapid recovery of local power grid. Taking Taishan Power Plant 1000 MW unit as a research object, the feasibility scheme of adding FCB function was analyzed and demonstrated on the basis of making full use of the original equipment design margin. The FCB test of TMCR 100% load was completed. The test results and problems during FCB process were discussed, and the corresponding countermeasures were proposed.
Investigation on Dynamic Characteristic of Geared Rotor System Composed of Ultrahigh Molecular Polyethylene Gear and Metal Gear
Authors: Pang Daqian , Ma Changjun , Zhang Xin , Liu Yue , Zhu Bingxian
Published: January 2021

A geared rotor system model consisting of UPE gears and steel gears for medium speed, medium load and long servo time is proposed. The solid models of steel-steel, steel-UPE and UPE-UPE gear systems were established. The dynamic models of steel-UPE gear system and UPE-UPE gear system were reconstructed by using the theoretical mechanical model of UPE. The time-varying meshing stiffness of three gear systems is analyzed. The vibration responses of three gear systems are studied by STFT method. The dynamic loads of three gear systems under different loads and rotational speeds are researched in detail, and the changing rules of dynamic loads of three gear systems under different loads and rotational speeds are revealed. At last, the first ten modes of three gear systems are calculated and the results are discussed. At the same time, the modal results are used to verify the correctness of the research on vibration response and dynamic load of three gear systems.
Analysis and location of Turn-To-Turn short circuit of rotor windings in generator
Authors: Zhang Yucheng , Sun Zenghuan
Published: January 2021

With the increase of generator running time, the probability of generator rotor problems increases constantly. In this paper, a generator is taken as an example. During maintenance, the generator is found to have the evidence of turn-to-turn short circuit of rotor windings by the repetitive surge oscilloscope method, which is verified by the AC impedance power loss test of the rotor winding. The position of turn-to-turn short circuit is determined by the inter-pole voltage method and the coil voltage method. The accuracy of the test method is further verified by the generator rotor’s return repair.
Fixed frequency Finite Control Set Model Predictive Control For Three-level APF
Authors: Sha MaiChao , Zhu RuiJin , Gong XueJiao
Published: January 2021

Active power filter can compensate harmonic and reactive power, Three level neutral point clamp (ANPC) has the characteristics of low output harmonic and low device loss. The control of three-level active power filter needs to consider multiple objectives. Finite control set model predictive control (FCS-MPC) is a new method which can add constraints and multi-objective control. According to the limit of the switch state, it can track the reference current, which has the characteristics of fast dynamic response and good compensation effect. This method not only keeps the neutral point voltage balance, but also solves the problem of unstable switching frequency.
Structure Design and Calibration of INS for Distributed POS Technology
Authors: Ma Zhen , Chen Xiyuan
Published: January 2021

With the development of science and technology, position and orientation system (POS) technology has become an important tool for airborne earth observation system, and plays an important role in both military and civil fields. The calibration of the device directly affects the accuracy of inertial navigation. Therefore, the paper designs a compact dual mode navigation system with high and low precision, which can be used in distributed POS system. Firstly, the status of IMU calibration technology is introduced. Then it introduces the working principle, structure design and layout design of fiber optic gyroscope (FOG) combination. Finally, the calibration experiment verifies that the designed FOG combination system meets the performance index.
Backward stochastic Volterra integral equations with jumps in a general filtration
Authors: Popier Alexandre
Published: January 2021

In this paper, we study backward stochastic Volterra integral equations introduced in Lin [Stochastic Anal. Appl.20(2002) 165–183] and Yong [Stochastic Process. Appl.116(2006) 779–795] and extend the existence, uniqueness or comparison results for general filtration as in Papapantoleonet al.[Electron. J. Probab.23(2018) EJP240] (not only Brownian-Poisson setting). We also considerLp-data and explore the time regularity of the solution in the Itô setting, which is also new in this jump setting.
The asymptotic shape theorem for the frog model on finitely generated abelian groups
Authors: Coletti Cristian F. , de Lima Lucas R.
Published: January 2021

We study the frog model on Cayley graphs of groups with polynomial growth rate D ≥ 3. The frog model is an interacting particle system in discrete time. We consider that the process begins with a particle at each vertex of the graph and only one of these particles is active when the process begins. Each activated particle performs a simple random walk in discrete time activating the inactive particles in the visited vertices. We prove that the activation time of particles grows at least linearly and we show that in the abelian case with any finite generator set the set of activated sites has a limiting shape.
Channel choice and coordination of fresh agricultural product supply chain
Authors: Yan Bo , Fan Jing , Wu Ji-Wen
Published: January 2021

By constructing a dual-channel fresh agricultural product (FAP) supply chain consisting of a retailer and a supplier, this paper considers the effect of fresh-keeping level on the freshness of perishable products and constructs a time-varying demand function based on freshness. The operating cost of the internet channel to the supplier has also been considered in the model. Optimal pricing strategy and profits of supply chain members under dual channels are investigated respectively in this paper. Comparing the optimal profit under traditional single-channel and dual-channel supply chain, we obtain the condition that the internet operating cost should satisfy. Given the situation where the supplier obtains profit while the retailer loses after the supplier introduced the internet channel, this paper proposes a revenue-sharing contract to make up for the loss of the retailer and achieves a win–win situation. Research shows that in the numerical analysis the supplier’s and the retailer’s profit can only be improved when the operating cost of the internet channel c0 and revenue-sharing ratio ψ are within a certain range. When ψ ≥ 0.4 and $ 0\le {c}_0\le \sqrt{\frac{2.34{\psi }^2+1.25\psi +7.39}{8.43{\psi }^3+4.62{\psi }^2+5.72\psi +9.05}}+8.64$, Pareto improvement will be attained on both sides in the supply chain.
The effects of social isolation on well-being and life satisfaction during pandemic
Authors: Clair Ruta , Gordon Maya , Kroon Matthew , Reilly Carolyn
Published: January 2021

The SARS-CoV-2 pandemic placed many locations under ‘stay at home” orders and adults simultaneously underwent a form of social isolation that is unprecedented in the modern world. Perceived social isolation can have a significant effect on health and well-being. Further, one can live with others and still experience perceived social isolation. However, there is limited research on psychological well-being during a pandemic. In addition, much of the research is limited to older adult samples. This study examined the effects of perceived social isolation in adults across the age span. Specifically, this study documented the prevalence of social isolation during the COVID-19 pandemic as well as the various factors that contribute to individuals of all ages feeling more or less isolated while they are required to maintain physical distancing for an extended period of time. Survey data was collected from 309 adults who ranged in age from 18 to 84. The measure consisted of a 42 item survey from the Revised UCLA Loneliness Scale, Measures of Social Isolation (Zavaleta et al., 2017), and items specifically about the pandemic and demographics. Items included both Likert scale items and open-ended questions. A “snowball” data collection process was used to build the sample. While the entire sample reported at least some perceived social isolation, young adults reported the highest levels of isolation, χ2(2) = 27.36, p < 0.001. Perceived social isolation was associated with poor life satisfaction across all domains, as well as work-related stress, and lower trust of institutions. Higher levels of substance use as a coping strategy was also related to higher perceived social isolation. Respondents reporting higher levels of subjective personal risk for COVID-19 also reported higher perceived social isolation. The experience of perceived social isolation has significant negative consequences related to psychological well-being.
Influence of defects on silicon heterojunction solar cell efficiency: Physical model and comparison with data
Authors: Zumbo Luca , Lerat Jean-Francois , Connelli Carmelo , Colletti Claudio , Gerardi Cosimo , Lombardo Salvatore
Published: January 2021

We have studied the influence of defects on silicon heterojunction solar cell efficiency by a method based on the comparison of electroluminescence (EL) image data with a finite element circuit model of solar cell efficiency. For this purpose, a general curve that relates the solar cell efficiency to a parameter representative of the defect strength, i.e., the loss of VOC, ∆VOC, from EL maps is obtained, and it is shown that the efficiency can be predicted with a good degree of confidence.
Implementation of complete Boolean logic functions in single spin–orbit torque device
Authors: Zhao Yunchi , Yang Guang , Shen Jianxin , Gao Shuang , Zhang Jingyan , Qi Jie , Lyu Haochang , Yu Guoqiang , Jin Kui , Wang Shouguo
Published: January 2021

All 16 Boolean logic functions in a single Ta/CoFeB/MgO device with perpendicular magnetic anisotropy were experimentally demonstrated based on the spin–orbit torque (SOT) effect. Furthermore, by combining with the voltage-controlled magnetic anisotropy (VCMA) effect, a novel SOT-MTJ (magnetic tunnel junction) prototype device with the assistance of the VCMA effect was further designed to perform magnetic field-independent logic operations. The numerical simulations were carried out, demonstrating the feasibility to realize all 16 Boolean logic functions in a single three-terminal device by applying the bias voltage and current injection as input variables. This approach provides a potential way toward the application of energy efficient spin-based logic, which is beyond the current von Neumann computing architecture.
Spontaneously formed quasicrystal grains in a pure metal
Authors: Wang Zhengming , Chang Tzu-Yi , Xu Donghua
Published: January 2021

Pure metals so far have been obtained in quasicrystal (QC) forms only by templation – epitaxial growth on a QC substrate. Here, we report spontaneous formation of dodecagonal QC (DDQC) grains in pure tantalum (Ta), an early transition metal normally in a body-centered-cubic crystal structure. The DDQC grains comprise icosahedral clusters assembled in accordance with the Stampfli triangle–square tiling scheme and are formed directly from the supercooled liquid and the β-Ta phases during thermal devitrification of a Ta metallic glass in molecular dynamics simulations using a realistic quantum mechanically based interatomic potential. They co-exist with β-Ta and are retainable to and stable at room temperature, with a slightly lower configurational energy than β-Ta.
Perpendicular magnetic anisotropy and its electrical control in FeNiB ultrathin films
Authors: Yamamoto Tatsuya , Nozaki Takayuki , Yakushiji Kay , Tamaru Shingo , Kubota Hitoshi , Fukushima Akio , Yuasa Shinji
Published: January 2021

We study the perpendicular magnetic anisotropy in (Fe100−xNix)80B20 (FeNiB) films with various Ni contents. Perpendicularly magnetized films are achieved when the Ni content is in the range of 30 at. %–70 at. %. An effective perpendicular magnetic anisotropy (PMA) constant of 1.1× 105 J/m3 is achieved for the (Fe50Ni50)80B20 film. We also fabricate magnetic tunnel junction devices containing FeNiB films, and electrical measurements show that a tunneling magnetoresistance ratio of more than 20% can be achieved for devices having an orthogonal magnetization configuration. The PMA of the FeNiB film clearly changes by varying the bias voltage applied along the FeNiB/MgO junction, and a voltage-controlled magnetic anisotropy (VCMA) efficiency of over 30 fJ/Vm is demonstrated. From systematic investigations, there is no clear correlation between PMA and VCMA efficiency in the FeNiB/MgO junction. These experimental results should facilitate the development of energy-efficient magnetic random-access memory.
Numerical simulation of magnetic skyrmions on flat lattices
Authors: Kapitan V. , Vasiliev E. , Perzhu A. , Kapitan D. , Rybin A. , Korol A. , Soldatov K. , Shevchenko Yu.
Published: January 2021

We studied several types of flat lattices with direct exchange and Dzyaloshinskii-Moriya interaction between spins: a honeycomb lattice with 3 nearest neighbours (NN), a square lattice with 4 NN and a hexagonal or triangular lattice with 6 NN. For the analysis of data obtained during the Monte Carlo simulation, a convolutional neural network was used for the recognition of different phases of the spin system which was dependent on simulation parameters such as DMI and external magnetic field (Hz). Based on these data, the phase diagrams (Hz, D) for the different lattices were plotted. The various states of the systems under observation were visualised and the boundaries between the different phases were defined as a spiral, a skyrmion and others. The data from the numerical experiments will be used in further studies to determine the model parameters of the systems for the formation of a stable skyrmion state and the development of methods for controlling skyrmions in a magnetic film.
Prediction of structural, electronic and magnetic properties of full Heusler alloys Ir2YSi (Y = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) via first-principles calculation
Authors: Prakash Roshme , Kalpana G.
Published: January 2021

First principles electronic structural calculation of full Heusler alloys Ir2YSi (Y= Sc to Ni) in the L21 (Cu2MnAl) and Xa (Hg2CuTi) structures have been studied using full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). From the total energy calculations, it has been observed that all these alloys are stable in L21 structure than Xa structure and also it is found that the alloys Ir2YSi (Y =V to Co) are ferromagnetically stable whereas the Ir2YSi (Y = Sc, Ti, and Ni) alloys are non-magnetic in their stable L21 structure. Spin polarized band structure calculations reveal that in Ir2YSi (Y= V to Co) alloys there is spin splitting of energy states around the Fermi level (EF) indicating ferromagnetism and moreover in Ir2YSi (Y = V, Cr, and Mn) alloys majority electrons have metallic behavior while minority electrons have semiconducting nature exhibiting half metallic ferromagnetic (HMF) nature. HMF property in Ir2YSi (Y = V, Cr, and Mn) alloys have been further confirmed from the integer total magnetic moment value of 3.0 µB, 4.0 µB and 5.0 µB per formula unit respectively. Spin polarization mainly arises from the interaction between 3d electrons of V/Cr/Mn atom and 5d electrons of Ir atom. This strong d-d hybridization between the transition atoms like Ir and V/Cr/Mn composing Heusler alloys is essential for the formation of gap at the EF between the valence and conduction bands. Our results show that Ir2YSi (Y= V, Cr, and Mn) will be suitable for ferromagnetic and spintronics applications.
First-principles prediction of rare-earth free permanent magnet: FeNi with enhanced magnetic anisotropy and stability through interstitial boron
Authors: Tuvshin D. , Ochirkhuyag T. , Hong S. C. , Odkhuu D.
Published: January 2021

Ab initio electronic structure calculations reveal that interstitial 2p elements (B, C, and N) have dramatic effects on the structural stability and intrinsic magnetic properties of L10-phase FeNi. Among the 3 possible interstitial impurities, only the B improves the L10-phase stability of FeNi and enhances its uniaxial magnetic anisotropy (0.7 MJ m−3) up to 2.6 MJ m−3. The underlying mechanism is elucidated in terms of single-particle energy spectra analyses along with atom- and orbital-resolved magnetocrystalline anisotropy energy, where both the Fe and Ni 3d level changes induced by charge rearrangement and 2p-3d hybridization are responsible. These findings point toward feasibility of enhancing the structural stability and energy product of 3d-only magnetic metals through the interstitial doping with 2p nonmetal elements.
Magnetic and electrical transport properties of Ru doped cobalt ferrite thin films with perpendicular magnetic anisotropy
Authors: Peda Monalisha , Kumar P. S. Anil
Published: January 2021

Epitaxial ferrimagnetic thin films of (Co, Ru) Fe2O4 were grown on MgO (001) substrate using pulsed laser deposition technique. Ruthenium substitution in cobalt ferrite has increased the conductivity by orders of magnitude, but it has a minimal effect on magnetic properties. The film has a high coercivity and perpendicular magnetic anisotropy (PMA), where the magnetic easy axis points perpendicular to the film surface. We report the magnetic and electrical transport properties here. The temperature variation of resistivity showed different conduction mechanisms at high and low-temperature regimes. Room temperature Hall measurement reveals “n” type carrier with a carrier concentration of 4×1020/cm3. The film showed negative MR and a linear decrement with the magnetic field without any saturation.
Passive piezomagnetic monitoring of structures subjected to in-service cyclic loading: Application to the detection of fatigue crack initiation and propagation
Authors: Ouaddi A. , Hubert O. , Furtado J. , Gary D. , He S.
Published: January 2021

In this research, the evolution of the piezomagnetic field of a low carbon steel under cyclic tensile stress was investigated. The objective was to explore the correlations between piezomagnetic signal measured by a fluxgate magnetometer with progressive changes that take place during the fatigue tests. Experiments show first that the piezomagnetic hysteresis loop changes drastically with the propagation of fatigue crack. A multiscale magneto-elastic model of the piezomagnetic behavior allows secondly the experimental cycles evolution to be explained.
Demographic trends and reproductive patterns in the northern hairy-nosed wombat (Lasiorhinus krefftii) at Epping Forest National Park (Scientific), central Queensland
Authors: Horsup Alan B. , Austin Jeremy J. , Fewster Rachel M. , Hansen Birgita D. , Harper Dave E. , Molyneux Jenny A. , White Lauren C. , Taylor Andrea C.
Published: January 2021

The critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii) currently exists at only two locations in Queensland. Management, research and monitoring of the species at the main Epping Forest National Park (Scientific) population has occurred over the last four decades using a variety of tools, with the most complete dataset being provided by burrow activity monitoring over that period. Following a series of trap-based surveys in the 1980s and 1990s, wombat monitoring has employed DNA profiling of hairs collected remotely on sticky tape set at burrow entrances (since 2000), and passive infrared (PIR) cameras (since 2011). These techniques have produced a wealth of new information on the species. Using this new information, we aim to: (1) summarise the available demographic data and present new estimates using novel techniques for L. krefftii at Epping Forest NP; and (2) characterise reproductive patterns and their relationship with environmental factors for L. krefftii at Epping Forest NP. We find an ongoing increase in the population size at Epping Forest National Park, supported by healthy levels of reproduction despite periods of poor environmental conditions, notwithstanding the finding that cumulative monthly rainfall six months prior to sampling influenced birth rates. This trend suggests that the population will likely reach carrying capacity in the near future. It is timely to harvest the population to provide founders to a new site to establish an additional population, which will also reduce the risk of extinction and help secure the future of the species.
Relational ontology and more-than-human agency in Indigenous Karen conservation practice
Authors: Paul Andrew , Roth Robin , Moo Saw Sha Bwe
Published: January 2021

Conservation scientists increasingly recognise the value of Indigenous knowledge in conservation practice. However, studies of Indigenous knowledge and resource management systems have often tended to overlook the role and agency of more-than-human beings and ceremonial protocols in mediating human–environment relationships. This paper presents results from community-based research with Karen communities in the Salween Peace Park, an innovative Indigenous-led conservation initiative in the autonomous Karen territory of Kawthoolei, on the border between Thailand and Burma, or Myanmar. Our findings detail ways in which relations with more-than-human beings, including spirits, constitute environmental governance in Karen communities. These findings compel externally situated conservation biologists to take relational ontologies seriously, allowing local interlocutors’ lived experience, knowledge, and theory to challenge culturally bound concepts such as resources, management, and conservation. In order to transform conservation biology through Indigenous perspectives, it is essential to pay attention to the relational world in which many Indigenous Peoples live. Doing so helps support a conservation practice attentive to the interdependence of all life in ways that uphold Indigenous Peoples’ rights of self-determination, cultural identity, and social relations with their ancestral lands. We argue that attending to these relations is essential to building community-based conservation collaborations with Indigenous Peoples that are more effective, sustainable, and just.
Potential for suppression of Rhizoctonia root rot is influenced by nutrient (N and P) and carbon inputs in a highly calcareous coarse-textured topsoil
Authors: Davey Rowena S. , McNeill Ann M. , Barnett Stephen J. , Gupta Vadakattu V. S. R.
Published: January 2021

Bioassays were undertaken in a controlled environment to assess whether the potential for suppression of Rhizoctonia root rot of wheat, in a highly calcareous topsoil, was positively influenced by nutrient (nitrogen (N) or phosphorus (P)) addition and whether any disease suppression response to augmented nutrition was affected by the addition of carbon (C), either as a readily available C source (sucrose) or as wheat stubble. The soil was P deficient, which limited plant growth, populations of putatively beneficial soil microorganisms, and microbial activity and diversity. This ultimately reduced potential for suppression of Rhizoctonia solani AG8. Addition of fertiliser P to the soil increased R. solani AG8 DNA and percent root infection but not the effectiveness of the pathogen. A positive effect of P fertiliser on plant growth partially compensated for the negative effect of increased root infection. Addition of P increased DNA for Microbacterium spp. where labile C had been added and in the presence of plant roots. Stubble addition alone, after 6 weeks of incubation, increased DNA for Pantoea agglomerans, Trichoderma A and Microbacterium spp. although differences in microbial activity and diversity between stubble treatments were only detected after the bioassay had commenced and P was added. Fertiliser P addition to stubble-amended soil resulted in less Rhizoctonia infection compared with that in soil without P or stubble addition. Effectiveness of R. solani AG8 was decreased by 50% with stubble amendment. The application of N alone did not have a marked effect on plant growth or potential for suppression of Rhizoctonia root disease. Agronomic management practices that affect quantity and lability of C input to soil, when combined with strategic P fertiliser decisions, are likely to improve the potential for development of suppression of Rhizoctonia root rot disease in cereal crops on alkaline and highly calcareous soils.
Classical calculation of radiative decay rates of hydrogenic Stark states
Authors: Horbatsch Michael , Horbatsch Marko
Published: January 2021

The Kepler–Coulomb problem is solved in parabolic coordinates and the Larmor radiation problem is analyzed to complement a previous study performed for the usual representation in spherical polar coordinates. The problem is then extended to include a weak electric field and a solution in terms of action-angle variables is provided. A comparison with quantum spontaneous decay rates shows that for azimuthal quantum number m = 0 states only transitions to nearby n −Δn principal quantum number states are described properly by the Wentzel–Kramers–Brillouin (WKB) quantized classical motions, but that for m > 0 reasonable results emerge for many values of Δn. A simple approximate expression for the lifetime of m ≠ 0 states emerges from the semi-classical analysis.
Tailoring the optical properties of dilute nitride semiconductors at the nanometer scale
Authors: Pettinari Giorgio , Marotta Gianluca , Biccari Francesco , Polimeni Antonio , Felici Marco
Published: January 2021

We report on the innovative approaches we developed for the fabrication of site-controlled semiconductor nanostructures [e.g. quantum dots (QDs), nanowires], based on the spatially selective incorporation and/or removal of hydrogen in dilute nitride semiconductor alloys [e.g. Ga(AsN) and (InGa)(AsN)]. In such systems, the formation of stable nitrogen-hydrogen complexes removes the effects nitrogen has on the alloy properties, which in turn paves the way to the direct engineering of the material’s electronic—and, thus, optical—properties: not only the bandgap energy, but also the refractive index and the polarization properties of the system can indeed be tailored with high precision and in a reversible manner. Here, lithographic approaches and/or plasmon-assisted optical irradiation—coupled to the ultra-sharp diffusion profile of hydrogen in dilute nitrides—are employed to control the hydrogen implantation and/or removal process at a nanometer scale. This results in a highly deterministic control of the spatial and spectral properties of the fabricated nanostructures, eventually obtaining semiconductor nanowires with controlled polarization properties, as well as site-controlled QDs with an extremely high control on their spatial and spectral properties. The nanostructures fabricated with these techniques, whose optical properties have also been simulated by finite-element-method calculations, are naturally suited for a deterministic coupling in optical nanocavities (i.e. photonic crystal cavities and circular Bragg resonators) and are therefore of potential interest for emerging quantum technologies.
Regulating the core/shell electric structure of Co3O4@Ni–Co layered double hydroxide on Ni foam through electrodeposition for a quasi-solid-state supercapacitor
Authors: Zhang Yuqiang , Wang Yan , Zhu Jiahui , Zhang Xubin , Cai Wangfeng
Published: January 2021

A flower-like structured electrode material of Co3O4@Ni–Co layered double hydroxide (LDH) grown on Ni foam (Co3O4@Ni–Co LDH/NF) was prepared via an in situ growth, annealing and electrodeposition process. The Co3O4@Ni–Co LDH/NF electrode was prepared with the optimized conditions of annealing temperature 300 °C, deposition time 20 min and Ni/Co ratio 1:1. The results showed that the as-prepared electrode material exhibited an excellent specific capacitance and great cycling stability. Furthermore, an quasi-solid-state supercapacitor was assembled using the prepared Co3O4@Ni–Co LDH/NF as the positive electrode and activated carbon on Ni foam (AC/NF) as the negative electrode. The as-assembled device presented a high energy density and power density.