检索结果-内蒙古大学图书馆

arXiv 2019年

作者： Dong, Xiaowen Morales, Alfredo J. Jahani, Eaman Moro, Esteban Lepri, Bruno Bozkaya, Burcin Sarraute, Carlos Bar-Yam, Yaneer Pentland, Alex Department of Engineering Science University of Oxford Oxford United Kingdom MIT Media Lab CambridgeMA United States New England Complex Systems Institute CambridgeMA United States MIT Institute for Data Systems and Society CambridgeMA United States Department of Mathematics and GISC Universidad Carlos III de Madrid Leganés Spain Mobile and Social Computing Lab Fondazione Bruno Kessler Trento Italy Behavioral Analytics & Visualization Lab Sabancı University Istanbul Turkey New College of Florida SarasotaFL United States Grandata Labs Buenos Aires Argentina

Urban income segregation is a widespread phenomenon that challenges societies across the globe. Classical studies on segregation have largely focused on the geographic distribution of residential neighborhoods rather than on patterns of social behaviors and interactions. In this study, we analyze segregation in economic and social interactions by observing credit card transactions and Twitter mentions among thousands of individuals in three culturally different metropolitan areas. We show that segregated interaction is amplified relative to the expected effects of geographic segregation in terms of both shopping activity and online communication. Furthermore, we find that segregation increases with difference in socio-economic status but is asymmetric, i.e., the amount of interaction from poorer to wealthier neighborhoods is considerably larger than vice versa. Our results provide novel insights into the understanding of behavioral segregation in human interactions with significant socio-political and economic implications. Copyright © 2019, The Authors. All rights reserved.

关键词： Geographical distribution

来源：评论

学校读者我要写书评

暂无评论

Ba12[BN2]6.67H4: A Disordered Anti-Skutterudite filled with Nitridoborate Anions

引用

Angewandte Chemie 2023年第4期136卷

作者： Sophia L. Wandelt Dr. Alexander Mutschke Dr. Dmitry Khalyavin Jennifer Steinadler Prof. Dr. Antti J. Karttunen Prof. Dr. Wolfgang Schnick Department of Chemistry University of Munich (LMU) Butenandtstr. 5–13 81377 Munich Germany Contribution: Conceptualization (lead) Formal analysis (lead) Investigation (lead) Validation (equal) Visualization (lead) Writing - original draft (lead) Writing - review & editing (equal) Chair of Inorganic Chemistry with Focus in Novel Materials Department of Chemistry TU Munich Lichtenbergstr. 4 85748 Garching Germany Heinz Maier-Leibnitz Zentrum (MLZ) TU Munich Lichtenbergstr. 1 85748 Garching Germany Contribution: Formal analysis (supporting) Investigation (supporting) Validation (supporting) Writing - original draft (supporting) Writing - review & editing (supporting) Rutherford Appleton Laboratory ISIS Neutron and Muon Source Didcot OX11 0QX UK Contribution: Data curation (supporting) Methodology (supporting) Writing - review & editing (supporting) Contribution: Formal analysis (supporting) Investigation (supporting) Writing - original draft (supporting) Writing - review & editing (supporting) Department of Chemistry and Materials Science Aalto University P.O. Box 16100 00076 Aalto Finland Contribution: Formal analysis (supporting) Investigation (supporting) Resources (supporting) Validation (supporting) Writing - original draft (supporting) Writing - review & editing (supporting) Contribution: Funding acquisition (lead) Project administration (lead) Resources (lead) Supervision (lead) Validation (equal) Writing - original draft (supporting) Writing - review & editing (supporting)

Skutterudites are of high interest in current research due to their diversity of structures comprising empty, partially filled and filled variants, mostly based on metallic compounds. We herein present Ba 12 [BN 2 ] 6.67 H 4 , forming a non-metallic filled anti-skutterudite. It is accessed in a solid-state ampoule reaction from barium subnitride, boron nitride and barium hydride at 750 °C. Single-crystal X-ray and neutron powder diffraction data allowed to elucidate the structure in the cubic space group Im (no. 204). The barium and hydride atoms form a three-dimensional network consisting of corner-sharing HBa 6 octahedra and Ba 12 icosahedra. Slightly bent [BN 2 ] 3− units are located in the icosahedra and the voids in-between. 1 H and 11 B magic angle spinning (MAS) NMR experiments and vibrational spectroscopy further support the structure model. Quantum chemical calculations coincide well with experimental results and provide information about the electronic structure of Ba 12 [BN 2 ] 6.67 H 4 .

关键词： Hydrides MAS NMR Neutron Diffraction Nitridoborates Skutterudite

来源：评论

学校读者我要写书评

暂无评论

Machine learning models of errors in large eddy simulation predictions of surface pressure fluctuations 47

Machine learning models of errors in large eddy simulation p...

引用

47th AIAA Fluid Dynamics Conference, 2017

作者： Barone, Matthew F. Fike, Jeffrey A. Chowdhary, Kamaljit S. Davis, Warren L. Ling, Julia Martin, Shawn Sandia National Labs AlbuquerqueNM87123 United States Aerosciences Department United States Extreme Scale Data Science and Analytics Department United States Scalable Analysis and Visualization Department United States Thermal/Fluids Science and Engineering Department United States Software Systems R&D Department United States

ISBN: (数字)9781624105005

ISBN: (纸本)9781624105005

We investigate a novel application of deep neural networks to modeling of errors in prediction of surface pressure fluctuations beneath a compressible, turbulent flow. In this context, the truth solution is given by Direct Numerical Simulation (DNS) data, while the predictive model is a wall-modeled Large Eddy Simulation (LES). The neural network provides a means to map relevant statistical flow-features within the LES solution to errors in prediction of wall pressure spectra. We simulate a number of flat plate turbulent boundary layers using both DNS and wall-modeled LES to build up a database with which to train the neural network. We then apply machine learning techniques to develop an optimized neural network model for the error in terms of relevant flow features. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Large eddy simulation

来源：评论

学校读者我要写书评

暂无评论

Extending the π-Conjugated System in Spiro-Type Hole Transport Material Enhances the Efficiency and Stability of Perovskite Solar Modules

引用

Angewandte Chemie 2023年第29期135卷

作者： Xuepeng Liu Bin Ding Mingyuan Han Zhenhai Yang Jianlin Chen Pengju Shi Xiangying Xue Rahim Ghadari Xianfu Zhang Rui Wang Keith Brooks Li Tao Sachin Kinge Songyuan Dai Jiang Sheng Paul J. Dyson Mohammad Khaja Nazeeruddin Yong Ding Beijing Key Laboratory of Novel Thin-Film Solar Cells School of New Energy North China Electric Power University Beijing 102206 P. R. China Contribution: Investigation (lead) Institute of Chemical Sciences and Engineering École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland Contribution: Methodology (lead) Contribution: Methodology (equal) Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences (CAS) Ningbo 315201 China Contribution: Data curation (equal) Contribution: Validation (equal) School of Engineering Westlake University Hangzhou 310024 China Contribution: Formal analysis (equal) Contribution: Investigation (equal) Computational Chemistry Laboratory Department of Organic and Biochemistry Faculty of Chemistry University of Tabriz Tabriz *** Iran Contribution: Software (lead) Contribution: Visualization (equal) School of Microelectronic & Faculty of Physics and Electronic Science Hubei University Wuhan 430062 China Toyota Motor Europe Toyota Motor Technical Centre Advanced Technology Div. Hoge Wei 33 1930 Zaventum Belgium Contribution: Resources (equal) Contribution: Supervision (equal) Contribution: Writing - original draft (equal) Writing - review & editing (equal) Contribution: Conceptualization (equal) Writing - original draft (equal) Writing - review & editing (equal) Contribution: Supervision (equal) Writing - original draft (lead)

Hole transport materials (HTMs) are a key component of perovskite solar cells (PSCs). The small molecular 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl)-amine-9,9′-spirobifluorene (spiro-OMeTAD, termed “Spiro”) is the most successful HTM used in PSCs, but its versatility is imperfect. To improve its performance, we developed a novel spiro-type HTM (termed “DP”) by substituting four anisole units on Spiro with 4-methoxybiphenyl moieties. By extending the π-conjugation of Spiro in this way, the HOMO level of the HTM matches well with the perovskite valence band, enhancing hole mobility and increasing the glass transition temperature. DP-based PSC achieves high power conversion efficiencies (PCEs) of 25.24 % for small-area (0.06 cm 2 ) devices and 21.86 % for modules (designated area of 27.56 cm 2 ), along with the certified efficiency of 21.78 % on a designated area of 27.86 cm 2 . The encapsulated DP-based devices maintain 95.1 % of the initial performance under ISOS-L-1 conditions after 2560 hours and 87 % at the ISOS-L-3 conditions over 600 hours.

关键词： Hole Transport Materials Modules Perovskite Solar Cells π-Conjugated System Stability

来源：评论

学校读者我要写书评

暂无评论

Development of machine learning models for turbulent wall pressure fluctuations 55

Development of machine learning models for turbulent wall pr...

引用

55th AIAA Aerospace sciences Meeting

作者： Ling, J. Barone, Matthew Davis, Warren Chowdhary, K. Fike, Jeffrey Thermal/Fluids Science and Engineering Department Sandia National Labs LivermoreCA94450 United States Aerosciences Department Sandia National Labs LivermoreCA94450 United States Scalable Analysis and Visualization Department Sandia National Labs LivermoreCA94450 United States Extreme Scale Data Science and Analytics Department Sandia National Labs LivermoreCA94450 United States Thermal/Fluids Science and Engineering Department Sandia National Labs AlbuquerqueNM87123 United States Aerosciences Department Sandia National Labs AlbuquerqueNM87123 United States Scalable Analysis and Visualization Department Sandia National Labs AlbuquerqueNM87123 United States Extreme Scale Data Science and Analytics Department Sandia National Labs AlbuquerqueNM87123 United States

ISBN: (数字)9781624104473

ISBN: (纸本)9781624104473

In many aerospace applications, it is critical to be able to model fluid-structure interactions. In particular, correctly predicting the power spectral density of pressure fluctuations at surfaces can be important for assessing potential resonances and failure modes. Current turbulence modeling methods, such as wall-modeled Large Eddy Simulation and Detached Eddy Simulation, cannot reliably predict these pressure fluctuations for many applications of interest. The focus of this paper is on efforts to use data-driven machine learning methods to learn correction terms for the wall pressure fluctuation spectrum. In particular, the non-locality of the wall pressure fluctuations in a compressible boundary layer is investigated using random forests and neural networks trained and evaluated on Direct Numerical Simulation data. © 2017 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Machine Learning Power Spectral Density Direct Numerical Simulation Convolutional Neural Network Compressible Boundary Layer Fluid Structure Interaction Turbulence Models Reynolds Averaged Navier Stokes Free Stream Velocity Velocity Profiles

来源：评论

学校读者我要写书评

暂无评论

Stabilization of Polar Nanoregions in Pb-free Ferroelectrics

引用

Physical Review Letters 2018年第20期120卷 207603-207603页

作者： A. Pramanick W. Dmowski T. Egami A. Setiadi Budisuharto F. Weyland N. Novak A. D. Christianson J. M. Borreguero D. L. Abernathy M. R. V. Jørgensen Department of Materials Science and Engineering City University of Hong Kong Kowloon Tong Hong Kong SAR Shull Wollan Center Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Department of Materials Science and Engineering University of Tennessee Oak Ridge Tennessee 37831 USA Institute of Materials Science Technische Universität Darmstadt Darmstadt 64287 Germany Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Neutron Data Analysis and Visualization Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Center for Materials Crystallography Department of Chemistry and iNANO Aarhus University 8000 Aarhus C Denmark MAX IV Laboratory Lund University SE-221 00 Lund Sweden

The formation of polar nanoregions through solid-solution additions is known to enhance significantly the functional properties of ferroelectric materials. Despite considerable progress in characterizing the microscopic behavior of polar nanoregions (PNR), understanding their real-space atomic structure and dynamics of their formation remains a considerable challenge. Here, using the method of dynamic pair distribution function, we provide direct insights into the role of solid-solution additions towards the stabilization of polar nanoregions in the Pb-free ferroelectric of Ba(Zr,Ti)O3. It is shown that for an optimum level of substitution of Ti by larger Zr ions, the dynamics of atomic displacements for ferroelectric polarization are slowed sufficiently below THz frequencies, which leads to increased local correlation among dipoles within PNRs. The dynamic pair distribution function technique demonstrates a unique capability to obtain insights into locally correlated atomic dynamics in disordered materials, including new Pb-free ferroelectrics, which is necessary to understand and control their functional properties.

关键词： Ferroelectricity Relaxor ferroelectrics Neutron pair-distribution function analysis

来源：评论

学校读者我要写书评

暂无评论

100 essential questions for the future of agriculture

Modern Agriculture

引用

Modern Agriculture 2023年第1期1卷

作者： Yuming Hu Taolan Zhao Yafang Guo Meng Wang Kerstin Brachhold Chengcai Chu Andrew Hanson Sachin Kumar Rongcheng Lin Wenjin Long Ming Luo Jian Feng Ma Yansong Miao Shaoping Nie Yu Sheng Weiming Shi James Whelan Qingyu Wu Ziping Wu Wei Xie Yinong Yang Chao Zhao Lei Lei Yong-Guan Zhu Qifa Zhang Wiley-VCH GmbH Weinheim Germany Contribution: Conceptualization (equal) Data curation (equal) Formal analysis (equal) Investigation (equal) Methodology (equal) Project administration (equal) Writing - original draft (equal) Writing - review & editing (equal) Contribution: Investigation (equal) Resources (equal) Writing - original draft (equal) Contribution: Data curation (equal) Investigation (equal) Visualization (equal) Contribution: Writing - review & editing (equal) State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources College of Agriculture South China Agricultural University Guangzhou China Contribution: Investigation (equal) Resources (equal) Horticultural Sciences Department University of Florida Gainesville Florida USA Rumen Biotechnology Laboratory Animal Nutrition Division ICAR-National Dairy Research Institute Karnal Haryana India Key Laboratory of Photobiology Institute of Botany Chinese Academy of Sciences Beijing China School of Economics and Management China Agricultural University Beijing China Guangdong Provincial Key Laboratory of Applied Botany & Agriculture and Biotechnology Research Center South China Botanical Garden Chinese Academy of Sciences Guangzhou China Institute of Plant Science and Resources Okayama University Kurashiki Japan School of Biological Sciences Nanyang Technological University Singapore City Singapore State Key Laboratory of Food Science and Technology China-Canada Joint Lab of Food Science and Technology (Nanchang) Nanchang University Nanchang China China Center for Agricultural Policy School of Advanced Agricultural Sciences Peking University Beijing China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing China State Key Laboratory of Plant Physiology and Biochemistry College of Life Sciences Zhejiang University Hangzhou Zhejiang China Department of Animal Plant and Soil Sciences La Trobe University Me

The world is at a crossroad when it comes to agriculture. The global population is growing, and the demand for food is increasing, putting a strain on our agricultural resources and practices. To address this challenge, innovative, sustainable, and inclusive approaches to agriculture are urgently required. In this paper, we launched a call for Essential Questions for the Future of Agriculture and identified a priority list of 100 questions. We focus on 10 primary themes: transforming agri-food systems, enhancing resilience of agriculture to climate change, mitigating climate change through agriculture, exploring resources and technologies for breeding, advancing cultivation methods, sustaining healthy agroecosystems, enabling smart and controlled-environment agriculture for food security, promoting health and nutrition-driven agriculture, exploring economic opportunities and addressing social challenges, and integrating one health and modern agriculture. We emphasise the critical importance of interdisciplinary and multidisciplinary research that integrates both basic and applied sciences and bridges the gaps among various stakeholders for achieving sustainable agriculture.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Continuous global optimization in surface reconstruction from an oriented point cloud

arXiv

引用

arXiv 2017年

作者： Pan, Rongjiang Skala, Vaclav School of Computer Science and Technology Shandong University Jinan China Centre of Computer Graphics and Data Visualization Department of Computer Science and Engineering University of West Bohemia Plzen Czech Republic

We introduce a continuous global optimization method to the field of surface reconstruction from discrete noisy cloud of points with weak information on orientation. The proposed method uses an energy functional combining flux-based data-fit measures and a regularization term. A continuous convex relaxation scheme assures the global minima of the geometric surface functional. The reconstructed surface is implicitly represented by the binary segmentation of vertices of a 3D uniform grid and a triangulated surface can be obtained by extracting an appropriate isosurface. Unlike the discrete graph-cut solution, the continuous global optimization entails advantages like memory requirements, reduction of metrication errors for geometric quantities, allowing globally optimal surface reconstruction at higher grid resolutions. We demonstrate the performance of the proposed method on several oriented point clouds captured by laser scanners. Experimental results confirm that our approach is robust to noise, large holes and non-uniform sampling density under the condition of very coarse orientation information. Copyright © 2017, The Authors. All rights reserved.

关键词： Global optimization

来源：评论

学校读者我要写书评

暂无评论

Surface reconstruction with higher-order smoothness

arXiv

引用

arXiv 2017年

作者： Pan, Rongjiang Skala, Vaclav School of Computer Science and Technology Shandong University Jinan250100 China Centre of Computer Graphics and Data Visualization Department of Computer Science and Engineering University of West Bohemia Plzen Czech Republic

This work proposes a method to reconstruct surfaces with higher-order smoothness from noisy 3D measurements. The reconstructed surface is implicitly represented by the zero level-set of a continuous valued embedding function. The key idea is to find a function whose higher-order derivatives are regularized and whose gradient is best aligned with a vector field defined by the input point set. In contrast to methods based on the first-order variation of the function that are biased towards the constant functions and treat the extraction of the isosurface without aliasing artifacts as an afterthought, we impose higher-order smoothness directly on the embedding function. After solving a convex optimization problem with a multi-scale iterative scheme, a triangulated surface can be extracted using the marching cubes algorithm. We demonstrated the proposed method on several data sets obtained from raw laser-scanners and multi-view stereo approaches. Experimental results confirm that our approach allows us to reconstruct smooth surfaces from points in the presence of noise, outliers, large missing parts and very coarse orientation information. Copyright © 2017, The Authors. All rights reserved.

关键词： Convex optimization

来源：评论

学校读者我要写书评

暂无评论

Understanding perspectives on sharing neutron data at oak ridge national laboratory

引用

data science Journal 2017年 16卷

作者： Donaldson, Devan Ray Martin, Shawn Proffen, Thomas Department of Information and Library Science School of Informatics and Computing Indiana University BloomingtonIN United States Neutron Data Analysis and Visualization Oak Ridge National Laboratory PO Box 2008 Oak RidgeTN United States

Even though the importance of sharing data is frequently discussed, data sharing appears to be limited to a few fields, and practices within those fields are not well understood. This study examines perspectives on sharing neutron data collected at Oak Ridge National Laboratory’s neutron sources. Operation at user facilities has traditionally focused on making data accessible to those who create them. The recent emphasis on open data is shifting the focus to ensure that the data produced are reusable by others. This mixed methods research study included a series of surveys and focus group interviews in which 13 data consumers, data managers, and data producers answered questions about their perspectives on sharing neutron data. data consumers reported interest in reusing neutron data for comparison/verification of results against their own measurements and testing new theories using existing data. They also stressed the importance of establishing context for data, including how data are produced, how samples are prepared, units of measurement, and how temperatures are determined. data managers expressed reservations about reusing others’ data because they were not always sure if they could trust whether the people responsible for interpreting data did so correctly. data producers described concerns about their data being misused, competing with other users, and over-reliance on data producers to understand data. We present the Consumers Managers Producers (CMP) Model for understanding the interplay of each group regarding data sharing. We conclude with policy and system recommendations and discuss directions for future research. © 2017 The Author(s).

关键词： Managers

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：