Characterizing structure of cross-disciplinary impact of global disciplines:A perspective of the Hierarchy of Science

Purpose:Interdisciplinary fields have become the driving force of modern science and a significant source of scientific innovation.However,there is still a paucity of analysis about the essential characteristics of disciplines’cross-disciplinary impact.Design/methodology/approach:In this study,we define cross-disciplinary impact on one discipline as its impact to other disciplines,and refer to a three-dimensional framework of variety-balance-disparity to characterize the structure of cross-disciplinary impact.The variety of cross-disciplinary impact of the discipline was defined as the proportion of the high cross-disciplinary impact publications,and the balance and disparity of cross-disciplinary impact were measured as well.To demonstrate the cross-disciplinary impact of the disciplines in science,we chose Microsoft Academic Graph(MAG)as the data source,and investigated the relationship between disciplines’cross-disciplinary impact and their positions in the Hierarchy of Science(HOS).Findings:Analytical results show that there is a significant correlation between the ranking of cross-disciplinary impact and the HOS structure,and that the discipline exerts a greater cross-disciplinary impact on its neighboring disciplines.Several bibliometric features that measure the hardness of a discipline,including the number of references,the number of cited disciplines,the citation distribution,and the Price index have a significant positive effect on the variety of cross-disciplinary impact.The number of references,the number of cited disciplines,and the citation distribution have significant positive and negative effects on balance and disparity,respectively.It is concluded that the less hard the discipline,the greater the cross-disciplinary impact,the higher balance and the lower disparity of cross-disciplinary impact.Research limitations:In the empirical analysis of HOS,we only included five broad disciplines.This study also has some biases caused by the data source and applied regression models.Practical implications:This study contributes to the formulation of discipline-specific policies and promotes the growth of interdisciplinary research,as well as offering fresh insights for predicting the cross-disciplinary impact of disciplines.Originality/value:This study provides a new perspective to properly understand the mechanisms of cross-disciplinary impact and disciplinary integration.

Content Characteristics of Knowledge Integration in the eHealth Field:An Analysis Based on Citation Contexts

Purpose:This study attempts to disclose the characteristics of knowledge integration in an interdisciplinary field by looking into the content aspect of knowledge.Design/methodology/approach:The eHealth field was chosen in the case study.Associated knowledge phrases(AKPs)that are shared between citing papers and their references were extracted from the citation contexts of the eHealth papers by applying a stem-matching method.A classification schema that considers the functions of knowledge in the domain was proposed to categorize the identified AKPs.The source disciplines of each knowledge type were analyzed.Quantitative indicators and a co-occurrence analysis were applied to disclose the integration patterns of different knowledge types.Findings:The annotated AKPs evidence the major disciplines supplying each type of knowledge.Different knowledge types have remarkably different integration patterns in terms of knowledge amount,the breadth of source disciplines,and the integration time lag.We also find several frequent co-occurrence patterns of different knowledge types.Research limitations:The collected articles of the field are limited to the two leading open access journals.The stem-matching method to extract AKPs could not identify those phrases with the same meaning but expressed in words with different stems.The type of Research Subject dominates the recognized AKPs,which calls on an improvement of the classification schema for better knowledge integration analysis on knowledge units.Practical implications:The methodology proposed in this paper sheds new light on knowledge integration characteristics of an interdisciplinary field from the content perspective.The findings have practical implications on the future development of research strategies in eHealth and the policies about interdisciplinary research.Originality/value:This study proposed a new methodology to explore the content characteristics of knowledge integration in an interdisciplinary field.

Spatial pattern analysis of forest trees based on the vectorial mark

Analysis of spatial patterns to describe the spatial correlation between a tree location and marks(i.e.,structural variables),can reveal stand history,population dynamics,competition and symbiosis.However,most studies of spatial patterns have concentrated on tree location and tree sizes rather than on crown asymmetry especially with direct analysis among marks characterizing facilitation and competition among of trees,and thus cannot reveal the cause of the distributions of tree locations and quantitative marks.To explore the spatial correlation among quantitative and vectorial marks and their implication on population dynamics,we extracted vertical and horizontal marks(tree height and crown projection area)characterizing tree size,and a vectorial mark(crown displacement vector characterizing the crown asymmetry)using an airborne laser scanning point cloud obtained from two forest stands in Oxfordshire,UK.Quantitatively and vectorially marked spatial patterns were developed,with corresponding null models established for a significance test.We analyzed eight types of univariate and bivariate spatial patterns,after first proposing four types.The accuracy of the pattern analysis based on an algorithm-segmented point cloud was compared with that of a truly segmented point cloud.The algorithm-segmented point cloud managed to detect 70–86%of patterns correctly.The eight types of spatial patterns analyzed the spatial distribution of trees,the spatial correlation between tree size and facilitated or competitive interactions of sycamore and other species.These four types of univariate patterns jointly showed that,at smaller scales,the trees tend to be clustered,and taller,with larger crowns due to the detected facilitations among trees in the study area.The four types of bivariate patterns found that at smaller scales there are taller trees and more facilitation among sycamore and other species,while crown size is mostly homogeneous across scales.These results indicate that interspecific facilitation and competition mainly affect tree height in the study area.This work further confirms the connection of tree size with individual facilitation and competition,revealing the potential spatial structure that previously was hard to detect.

An Improved Modulation Strategy for Single-phase Three-level Neutral-point-clamped Converter in Critical Conduction Mode

Two-level totem-pole power factor correction(PFC)converters in critical conduction mode(CRM)suffer from the wide regulation range of switching frequency.Besides,in highfrequency applications,the number of switching times increases,resulting in significant switching losses.To solve these issues,this paper proposes an improved modulation strategy for the single-phase three-level neutral-point-clamped(NPC)converter in CRM with PFC.By optimizing the discharging strategy and switching state sequence,the switching frequency and its variation range have been efficiently reduced.The detailed performance analysis is also presented regarding the switching frequency,the average switching times,and the effect of voltage gain.A 2 k W prototype is built to verify the effectiveness of the proposed modulation strategy and analysis results.Compared with the totem-pole PFC converter,the switching frequency regulation range of the three-level PFC converter is reduced by 36.48%and the average switching times is reduced by 45.10%.The experimental result also shows a 1.2%higher efficiency for the three-level PFC converter in the full load range.

高灵敏度和高线性度的可拉伸应变传感器的分层结构设计

对柔性电子设备日益增长的需求使得开发具有高灵敏度和高线性度的传感器更加迫切.由于拉伸应变下不可逆结构损伤诱导电阻线性急剧增加,现有的可拉伸应变传感器难以完美地同时实现这两个特性.针对这一问题,本文提出了一种兼具表面褶皱和体相梯度孔隙的新型分级互连结构,利用水热活化机制精确控制纳米级褶皱间距,通过调控相分离中热力学和动力学行为构筑出体相梯度多孔结构,通过改变器件两侧曲率实现各向异性特征,深入研究各种设计的功效、量化几何结构对灵敏度的有效贡献和追踪形态演变.基于器件显著的灵敏度和各向异性,所制备的传感器能够有效监测静态和动态位移、表面运动、二维应变信号变化以及预测液位随时间变化.本工作为实现高质量的感知能力提供了一种广泛适用、适应性强、可扩展且具有成本效益的方法.

结合激光与视觉点云的古遗迹三维重建应用

针对单一点云数据在古遗迹数据存档和模型重建过程中存在数据缺失的问题,以柬埔寨吴哥女王宫遗址为例,提出一套完整和高效的数字化记录与重建方案。通过结合地基激光雷达点云与无人机影像视觉点云,可以解决模型重建过程中激光与视觉点云的配准和融合以及模型构建与修补等关键问题,从而获得目标对象的三维模型。在此基础上,进一步提出的模型应用成果场景漫游动画和平立剖面图,能够更好地为吴哥女王宫保护、修复和研究提供静态和动态数据基础。所提方案能够为古遗迹保护过程中的数据采集、数字化存档、数据分析、场景展示和遗迹修复等多方面提供数据基础与技术参考,进一步推动激光雷达在该领域中的应用。

Effects of bias voltage on coating structures and anticorrosion performances of PA-PVD Al coated NdFeB magnets

Al coated NdFeB magnets were prepared by plasma-assisted-physical-vapor-deposition(PA-PVD)method fo r enhancing the corro sion resistance.Mo rphologies and structures were characterized by an Xray diffractometer and a scanning electron microscope.Corrosion behaviors of the samples with different bias voltages were studied by electrochemical methods and neutral salt spray test,respectively.The bias voltage during the deposition process was optimized according to the coating structures and corrosion resistances.The density and flatness of Al coating increase with increasing the bias voltage,and at the same time the thickness decreases.The coating density and thickness turn to be stable when bias voltage is 1800 V.Also,the corrosion behaviors of PA-PVD Al coatings in different media,such as NaOH,HNO_(3) and NaCl solutions,were studied.The self-corrosion potentials(E_(corr)) of PA-PVD Al coatings almost keep constant in NaOH and HNO_(3) solutions with diffe rent concentrations.However,the self-corrosion current densities(J_(corr)) decrease with the increasing concentrations.E_(corr) shifts to negative potential and J_(corr)decreases gradually when increasing the concentration of NaCl solution.The corrosion mechanisms of Al coatings are discussed based on the corrosion behaviors in different media.

Stochastic Programming for Cost Optimization in Geographically Distributed Internet Data Centers

The development of cloud computing has accel-erated the worldwide growth of internet data centers(IDCs).While a large portion of the energy consumption generated by intense computation introduces greater operation expenditures to the IDC enterprises.To manage the overall costs and utilize resources to their fullest extent,this paper introduces the concept of spatio-temporal workload allocation among the geographically distributed IDCs within a cloud,with the guarantee of the workload completion time and the consideration of computing service delay penalties by introducing the cost of inconvenience.Apart from the effort of the workload migration,the spatio-temporal variance of the renewable energies in the data center microgrids(DMGs)is fully considered in this paper.What's more,as the power consumed by the IDCs are primarily converted into heat,the waste heat recovery process is embedded in each IDC to demonstrate the effectiveness of the repurposed heat,which can be used by the residential heating demand in the thermal system,for total cost reduction and energy usage efficiency in the whole operating system.Applying real-life data traces of the electricity price,renewable energies and heating demand,these extensive evaluations demonstrate that both spatial and temporal complementary attempts on the supply side and demand side,along with power and thermal complementary efforts,can significantly reduce the overall cost for the IDC enterprise.

Corrosion resistance and mechanical properties of (Ho,Nd)FeB magnets

(Ho,Nd)FeB magnets with different Ho contents were prepared by Ho substitution for part of Nd during the casting process.Effects of Ho contents on the corrosion resistance and mechanical properties of(Ho,Nd)FeB magnets were analyzed by a highly accelerated aging tester,an electrochemical workstation,a microhardness tester,a bending tester,a scanning electron microscope and an X-ray diffractometer.Results show that the addition of Ho can change the main phase structure,optimize the distribution of rare-earth rich(RE-rich) phases in grain boundary,and improve the corrosion resistance and mechanical properties of NdFeB magnets.When the content of Ho increases from 0 to 21.0 wt%,the weight loss of magnets decreases from 2.672 to 0.933 mg/cm^(2),and the microhardness and bending strength increase from 528.74 HV and 374.92 MPa to 633.84 HV and 459.80 MPa,respectively.