bluuebunny/crossref_metadata_2025_split huggingface dataset:
Propagation invariance and dark hollow structures of sinh-Gaussian beams with small complex parameters
Authors: Zhu Kaicheng , Liang Ruisheng , Yi Yajun , Zhu Jie , Tang Huiqin 
Published: January 2021

Abstract
Through investigating the sinh-Gaussian beam with complex beam parameters, it is the first time to find that such beams can carry vortices and exhibit dark hollow intensity distributions when the complex beam parameters are sufficiently small. A closed-form propagation equation for sinh-Gaussian beams through paraxial ABCD optical systems is derived based on the Collins formula and illustrated with numerical methods. It is shown that the perfect hollow configuration can retain a quite long propagating distance under small complex beam parameters. The analytical discussions affirm the numerical conclusions.
Research on Control Strategy of Z-source Photovoltaic Grid-connected Inverter Based on Sliding Mode Control
Authors: Zheng Yunhong , Zhang Qingquan , Huang Xumin 
Published: January 2021

Abstract
This paper proposes a photovoltaic grid-connected inverter based on a Z-source NPC three-level topology to achieve buck-boost control and improve the transmission efficiency of the system. In view of the instability of the output power of the photovoltaic system, which affects the output of the grid-connected inverter, this paper proposes a dual closed-loop sliding mode control strategy. The DC bus voltage outer loop of this strategy adopts traditional sliding mode control and grid-connected current The inner loop adopts PI control to weaken the system chatter. The anti-interference ability of photovoltaic grid-connected system and harmonic content of grid-connected current were studied through the Matlab/Simulink simulation platform. The results show that the control strategy can effectively improve the robustness of the system and reduce the harmonic content of grid-connected current.
Experimental study on dynamic characteristics of a quasi-zero stiffness vibration isolator
Authors: Liu Yanqi , Song Chunfang , Xu Longlong , Ji Wen 
Published: January 2021

Abstract
In this paper, a kind of quasi-zero stiffness isolator with cam-roller nonlinear spring mechanism as negative stiffness mechanism is studied by sinusoidal sweep frequency experiment, sinusoidal constant frequency experiment and half-sinusoidal impact experiment. The dynamic response characteristics and impact resistance of quasi-zero stiffness isolator are analyzed. The experimental results show that when the excitation is constant, the dynamic response of the quasi-zero stiffness isolation system has a response peak, and the response acceleration and displacement all increase first and then decrease with the increase of frequency. When the excitation amplitude increases, the initial isolation frequency becomes large and the effective isolation bandwidth becomes narrow. For the half-sinusoidal acceleration impact with the pulse width less than 10ms and excitation acceleration less than 13.0g, the quasi-zero stiffness isolation system has excellent isolation and cushioning performance.
Comprehensive Evaluation Model of Power Grid Development Potential Considering Inventory and Incremental Equipment
Authors: Chen Meng , Niu Dongxiao , Geng Shiping , Guo Xiaopeng 
Published: January 2021

Abstract
Reasonable evaluation of the development potential of power grid is an important guarantee for power planning and investment. In this paper, the evaluation index system of power grid development potential is constructed, and based on the operation status of the existing equipment of the power grid, as well as the operation capacity of incremental equipment after the projects under construction and planning are put into operation, the evaluation model of power grid development potential considering the existing / incremental equipment is constructed. Finally, through the verification of Tianjin Power Grid, the index system and method mentioned in this paper are easy to implement and can evaluate the development potential of power grid comprehensively and accurately.
Research on Harmonic Resonance Mitigation Based on Improved Modal Sensitivity Analysis
Authors: Pan Aiqiang , Zhao Jinshuai , Zhang Peng , Pan Ling 
Published: January 2021

Abstract
Among the methods used for mitigation of harmonic resonance, modal analysis theory and modal sensitivity can be used to illuminate the nature and properties of this phenomenon, and are thus widely applied. In this paper, an improved modal sensitivity-based method is proposed to reliably suppress the harmonic resonance. First, we show that the current resonance mitigation schemes that are guided by traditional modal sensitivity are not always robust in some cases. Then, through a theoretical analysis, the roots of the shortcomings of the traditional modal sensitivity are determined. The key factor is that the modal sensitivity of a network component is not always constant but tends to vary with adjustment of the component parameters. Finally, to quantify this sensitivity variation and improve the robustness of the analysis results, a second-order modal sensitivity and a critical index are proposed. The results of the test system indicate that the proposed indexes can accurately show the effects of each network component on the resonance, thus are useful in the design of the corresponding mitigation scheme.
The application of LED illumination and intelligent control in plant factory, a new direction for modern agriculture: A Review
Authors: Arcel Mulowayi Mutombo , Lin Xiaoteng , Huang Jingyi , Wu Jiatong , Zheng Shuhe 
Published: January 2021

Abstract
Because of its cold light source and adjustable spectrum characteristics, light-emitting diode (LED) is widely used in modern agriculture, it can promote the growth and photomorphogenesis of the plant, also can improve yield and quality. Here, we introduce the advantages of LED over traditional light sources, and analyze the effects of different wavelengths of light on phototrophic plants and the ways in which different light detection systems interact in plants. We also analyze the effects of LED illumination on plants, the response of plants to LED illumination systems. In addition, we summarize the typical LED supplement light devices and intelligent control system in the world, and introduce their working methods and advantages respectively. Finally, we look forward to the future development direction and application prospects of LED with the intelligent control and machine in modern agriculture.
Statistical Channel Modelling of Millimetre Waves at 28 GHz and 73 GHz Frequency Signals Using MIMO Antennas
Authors: Ram Nanik , Gao Hongmin , Qin Huanyao , Oo Min Thant , Htun Ye Thet 
Published: January 2021

Abstract
To meet the demand of high spectrum requirement and high-speed wireless communication in future, millimetre waves (mm-Wave) can play a very important role for it. Millimetre waves starting from 30 GHz and ending at 300 GHz can solve the problems like high throughput, faster data rates and capacity. Millimetre waves can help to achieve higher gain by using high dimensional antenna array technology. Beamforming and spatial multiplexing are very famous techniques that can help to increase the gain when antenna arrays are used. Channel modelling plays a very important role in determining the possibility of deploying the wireless communication system. In this research paper, the major challenges regarding the mm-Wave channel modelling are identified and the statistical behaviour of mm-Wave channel at 28GHz and 73 GHz is explained with the help of NYUSIM software. The power loss, power delay profile and path loss, angle of arrival and departure are simulated in this work. These simulations are performed using multiple antennas configuration along with considering the effect of atmospheric impairments like rain, humidity and temperature.
Design of load data simulation source
Authors: Sun Yong , Wang Jianmin , Shi Jiaxiang 
Published: January 2021

Abstract
In the remote sensing satellite system, the main function of the data transmission subsystem is to receive all the data transmitted by the payload subsystem and then transmit it accurately to the data receiving station on the ground. In the absence of satellite payloads, to meet the requirements of the joint remote sensing satellite test link, we studied and designed a load data simulation source that can simultaneously output four channels of continuous data at different rates, and there are two operating modes to choose from. This design adopts Kintex UltraScale series FPGA with configurable Microblaze embedded soft core as the core controller, and the peripheral circuit includes four pieces of 2GB DDR4 memory, power supply and LVDS interface output. The actual test results show that the load data simulation source has high stability and good universality, and can perfectly meet the ground debugging and testing requirements of remote sensing satellite data transmission subsystem.
A Voltage Control Model of Multi-ports DC Transformer
Authors: Wu Hao 
Published: January 2021

Abstract
DC transformer (DCT) is basic and important power conversion equipment in DC distribution network. DC transformer adopts power electronic switches and high-frequency transformer, which can realize power conversion. Multi-ports DCT can connect many different types of power supply or load equipment, and can flexibly control the current, voltage and power flow of multiple ports, which is widely used in DC distribution network. In this paper, the output voltage control model of multi-ports DCT in steady state is established. Combined with the control model, the mechanism of controlling the phase-shift angle to realize the output voltage control is proved mathematically. The correctness of the control model is verified by simulation.
An approach of target photometric measuring for theodolite visible light imaging
Authors: Chen Shengyi , Fan Chaoran , Xu Zhilei , Zhang Feng , Li Xiaoxue 
Published: January 2021

Abstract
Photoelectric theodolite is important optical measurement equipment in pelagic aerospace TT&C systems. The visible light imaging method helps capture significant information of the observed target, photometric information is one of them. To achieve expediently and quickly target photometric measuring, it studies and realizes a measuring method, by using stars in the same field of view as the observed target in this paper. Firstly, it calculates the gray values for target and star by image processing algorithm in the image captured by theodolite. Then magnitude information of the star is obtained by using a star catalogue. Lastly, magnitude of the target is calculated by antitheses method. The approach is implemented to investigate the measuring performance and an experiment is carried out by using images containing at least two stars. The result shows good performance of the proposed method.
Analysis of the influence of the contact mode of the rolling elements of the slewing bearing on its stability
Authors: Deng Biao , Chen Jianwei , Guo Yang , Tang Shengjin 
Published: January 2021

Abstract
The stability of the rolling elements in the slewing bearing is an important factor that determines the smooth rotation of the slewing bearing. The slewing radius of the slewing bearing is large and the load is complicated. In this paper, the contact relationship between the rolling elements and the raceway is established by establishing a slice model of the slewing bearing. Considering the effects of axial load and radial load, respectively, the contact deformation and displacement changes of the rolling elements are analyzed. The simulation results show that the rolling elements of the two-point contact slewing bearing rotate during the load process, and the four-point contact slewing bearing is in the axial direction. Under load, the rolling contact state in the raceway with the raceway is stable without spinning; under radial load, the contact relationship between the rolling element and the four-point contact raceway at this time is essentially two-point contact, but compared to the one used Two-point contact raceway, the rolling elements have better radial stability in the newly designed raceway
Analysis of the influence of raceway structure on contact characteristics of turntable bearing
Authors: Deng Biao , Chen Jianwei , Guo Yang , Tang Shengjin 
Published: January 2021

Abstract
Turntable bearing is widely used in heavy industry. Raceway structure is the most direct factor that affects the contact stress change between raceway and rolling element. Therefore, it is the key to improve the safety of turntable bearing and determine the processing technology reasonably to study the stress distribution of contact area in different raceways. In this paper, the finite element slicing model of rolling element and raceway in turntable bearing is established in ABAQUS. Under the action of axial load and radial load, the distribution characteristics of contact stress of raceway are compared under different raceway structures. The finite element results show that, compared with the two-point contact disc bearing, the rolling element and raceway in four point contact turntable bearing are in four point contact under axial load, The contact stress distribution of raceway is uniform, which is a pair bearing distribution. However, when only considering the radial load, the rolling element and raceway are in two-point contact, and the contact stress distribution characteristics are consistent with those of two-point contact rotary table bearing.
Association of short-term air pollution with systemic inflammatory biomarkers in routine blood test: a longitudinal study
Authors: Di Niu , He Weiliang , Zhang Kaihua , Cui Jian , Chen Jiang , Cheng Jinming , Chu Bao , Li Shanshan , Xie Yinyu , Xiang Hao , Wang Hebo , Chen Gongbo , Guo Yuming 
Published: January 2021

Abstract
The biological mechanisms behind health effects of air pollution have not been well known. Inflammation plays an important role in occurrence and development of a wide range of diseases. In this study, we assessed the effects of short-term exposure to ambient air pollution on systemic inflammatory biomarkers among 12 508 participants who underwent routine physical examination annually at the Hebei General Hospital in Shijiazhuang, China. For each participant, white blood cell count (WBC), lymphocytes, neutrophils and eosinophils were measured for two or three times during September 2016 to December 2018. Daily concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3) and particulate matter less than 2.5 µm in aerodynamic diameter (PM2.5) were interpolated to each district, where the participants worked. The linear mixed-effects regression with a constrained distributed lag model was applied to examine the associations between air pollution and inflammatory biomarkers during lag 0–14 d. It was observed that WBC, neutrophils and eosinophils [percent change (%Δ) and 95% confidence interval (95%CI)] significantly decreased by −0.07 (−0.11, −0.04), −0.08 (−0.12, −0.03) and −0.15 (−0.25, −0.05) at lag 14 d, associated with per 10 µg m−3 increase in O3. WBC, lymphocytes and eosinophils (%Δ and 95%CI) significantly elevated by 0.08 (0.04, 0.12), 0.16 (0.11, 0.21) and 0.22 (0.10, 0.35) at lag 0 d, associated with per 10 µg m−3 increase in PM2.5. This study reveals short-term effects of air pollution on systemic inflammatory biomarkers in routine blood test, which is helpful for further study to explore the biological mechanisms.
Why scale is vital to plan optimal Nature-Based Solutions for resilient cities
Authors: Hutchins MG , Fletcher D , Hagen-Zanker A , Jia H , Jones L , Li H , Loiselle S , Miller J , Reis S , Seifert-Dähnn I , Wilde V , Xu C-Y , Yang D , Yu J , Yu S 
Published: January 2021

Abstract
A need for multi-functional assessment tools evaluating trade-offs and co-benefits for various types of Nature-Based Solutions (NBS) has been increasingly identified in recent years. Methodologically, concepts for a tool are presented which include quantifying the demand and potential for NBS to enhance ecosystem service (ES) provision, and linking ESs to readily quantifiable and legislatively-relevant environmental quality indicators (EQIs). The objective of tool application is to identify optimal NBS placement across a diverse set of socio-environmental indicators, whilst also incorporating issues of relative location of areas of implementation and benefit accrual. Embedded within the tool is the importance of evaluating outcomes in terms of economic benefits and of sustainable development goals. The concepts are illustrated with simplified examples, relating to the case of implementing urban forestry as an exemplar NBS. By summarising the knowledge base it is demonstrated that benefits of NBS are substantially scale-dependent in two main respects; those of extent and proximity to receptors. Evaluation tools should be capable of quantifying scale-dependence. The substantive importance of these considerations and how their dynamics vary between indicators and services is illustrated graphically through schematic functions. When developed, the tool should be used as a focus for consultation and co-design to pinpoint the size of NBS necessary to achieve a sufficient level of benefit for a particular receptor. This could be measured against target levels of benefit for each indicator, distinguishing between primary intended outcomes and those co-benefits or trade-offs that are secondary or unintended.
Kernels for non interacting fermions via a Green’s function approach with applications to step potentials
Authors: Dean David S , Le Doussal Pierre , Majumdar Satya N , Schehr Grégory , Smith Naftali R 
Published: January 2021

Abstract
The quantum correlations of N non interacting spinless fermions in their ground state can be expressed in terms of a two-point function called the kernel. Here we develop a general and compact method for computing the kernel in a general trapping potential in terms of the Green’s function for the corresponding single particle Schrödinger equation. For smooth potentials in one dimension the method allows a simple alternative derivation of the local density approximation for the density and of the sine kernel in the bulk part of the trap in the large N limit. It also recovers the density and the kernel of the so-called Airy gas at the edge. This method allows the analysis of the quantum correlations in the ground state when the potential has a singular part with a fast variation in space. For the square step barrier of height V
0 in one dimension, we derive explicit expressions for the density and for the kernel. For large Fermi energy μ > V
0 it describes the interpolation between two regions of different densities in a Fermi gas, each described by a different sine kernel. Of particular interest is the critical point of the square well potential when μ = V
0. In this critical case, while there is a macroscopic number of fermions in the lower part of the step potential, there is only a finite O(1) number of fermions on the shoulder, and moreover this number is independent of μ. In particular, the density exhibits an algebraic decay ∼1/x
2, where x is the distance from the jump. Furthermore, we show that the critical behavior around μ = V
0 exhibits universality with respect to the shape of the barrier. This is established (i) by an exact solution for a smooth barrier (the Woods–Saxon potential) and (ii) by establishing a general relation between the large distance behavior of the kernel and the scattering amplitudes of the single-particle wave-function.
Land Suitability for Potential Jatropha Plantation in Malaysia
Authors: Suhana Mokhtar Ernieza , Md Akhir Norshahirah , Ain Mohd Zaki Nurul , Melissa Muharam Farrah , Pradhan Biswajeet , Salihu Lay Usman 
Published: January 2021

Abstract
Malaysia has embarked on several initiatives and policies towards renewable energy for improving quality. Jatropha Curcas is an oil seed-bearing plant, which potentially yields as a source of energy in the form of biodiesel. However, research on the determination of the potentially suitable area of Jatropha plant can be allocated still limited. This study aims to carry out a land suitability study on the Jatropha plantation using the geospatial technique such as Geographical Information System (GIS) and remote sensing. To achieve the aim, the objectives of this study are to i) determine significant weightage of parameters for Jatropha plantation and ii) identify the suitable location Jatropha plantation. The study area is carried out at peninsular Malaysia, and five (5) variables such as rainfall, temperature, land-use, soil and elevation data were used to achieve the analysis. The analytical hierarchy process (AHP), in the combination of Geographical Information System (GIS) methods, was applied to compute the weightage of the selected criteria, which is in geospatial data types. A map of the potential Jatropha location was generated using the criteria weightage. This study can help the cultivation of Jatropha in suitable areas and may reduce the burden on fossil fuels. It can assist smallholder-based initiatives to promote Jatropha cultivation on farmer-owned to enhance their living circumstances.
Assessment of Coastal Altimetry Data in the South China Sea using Multiple Frequency Approaches
Authors: Mohd Hairy Ansar Andi , Hassan Md Din Ami , Idris Khairulnizam M , Hanif Hamden Mohammad , Nizam Uti Mat , Liew Jeng U 
Published: January 2021

Abstract
With a coastline length extending over 13,000 km, including the Malaysia region, the South China Sea presents a challenge to retrieve high quality data along the coastal area especially the sea level anomaly and significant wave height. Currently, coastal altimetry is still facing some issues especially when using the low frequency data such as data lacking near the coast, questionable data accuracy since the altimeter footprint contaminated with the land and less coverage of data from the installed ground truth data. This study aims to assess the coastal altimetry data of sea level and significant wave height in the South China Sea using low and high frequency approaches. This study involved deriving data from sea level anomaly (SLA) and significant wave height (SWH) through the use of Prototype for Expertise on AltiKa for Coastal, Hydrology and Ice (PEACHI) for high frequency and Radar Altimeter Database System (RADS) for low frequency of altimetry and ground truth station which is from tide gauge and Acoustic Wave and Current Profiler (AWAC). Comparison between altimetry and ground truth data has been made in order to validate the significant agreement between them. The validation of the data is to evaluate both types of frequencies with respect to the coastal distance. Consequently, the high frequency results for coastal results with a root mean square reliable ±0.14 metre level for the sea level anomaly (SLA) and ±0.18 metre level for significant wave height (SWH) are more reliable. PEACHI distance-to-coast data obtained a sufficient standard residual deviation ranging from 0 cm to 2.87 cm compared to RADS altimetry ranging from 0.08 cm to 14.20 cm. The findings of this study indicate that the coastal altimetry data benefit coastal development, coastal defence, monitoring and tourism by various related agencies.