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Buoyancy and turbulence-driven atmospheric circulation over urban areas

Journal of Environmental Sciences 2017年第9期29卷 63-71页

作者： Yifan Fan Julian Charles roland Hunt Yuguo Li Department of Mechanical Engineering The University of Hong KongHong KongChina Department of Earth Sciences University College LondonLondonWC1E6BTUK Malaysian Commonwealth Studies Centre CambridgeCB23RFUK

In the buoyancy and turbulence-driven atmospheric circulations（BTDAC） that occur over urban areas where the approach means wind speeds are very low（less than turbulent fluctuations and typically 3 m/sec）, the surface temperatures are significantly higher than those in the external rural areas, and the atmosphere above the mixing layer is stably stratified. In this paper, the mechanisms of BTDAC formation are studied through laboratory experiments and modelling, with additional low-level inflow from external rural areas and a divergent outflow in the opposite direction in the upper part of the mixed layer. Strong turbulent plumes in the central region mix the flow between lower and higher levels up to the inversion height. There are shear-driven turbulent eddies and weaker buoyant plumes around the periphery of the urban area. As the approach flow is very weak,the recirculating streamlines within the dome restrict the ventilation, and the dispersion of pollution emitted from sources below the inversion height leading to a rise in the mean concentration. Low-level air entrained from rural areas can, however, improve ventilation and lower this concentration. This trend can also be improved if the recirculating structure of the BTDAC flow pattern over urban areas breaks down as a result of the surface temperature distribution not being symmetrical, or as the approach wind speed increases to a level comparable with the mean velocity of circulation, or（except near the equator） the urban area is large enough that the Coriolis acceleration is significant.

关键词： Urban heat island Buoyancy and turbulence-driven Eddy structures Atmospheric circulation Pollutant dispersion

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Topic discovery and evolution in scientific literature based on content and citations

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Frontiers of Information Technology & Electronic Engineering 2017年第10期18卷 1511-1524页

作者： Hou-kui ZHOU Hui-min YU roland HU College of Information Science & Electronic Engineering Zhejiang University Hangzhou 310027 China State Key Lab of CAD & CG Zhejiang University Hangzhou 310027 China School of Information Engineering Zhejiang A &F University Lin'an 311300 China Zhejiang Provincial Key Laboratory of Forestry Intelligent Monitoring and Information Technology Lin'an 311300 China

Researchers across the globe have been increasingly interested in the manner in which important research topics evolve over time within the corpus of scientific literature. In a dataset of scientific articles, each document can be considered to comprise both the words of the document itself and its citations of other documents. In this paper, we propose a citationcontent-latent Dirichlet allocation(LDA) topic discovery method that accounts for both document citation relations and the content of the document itself via a probabilistic generative model. The citation-content-LDA topic model exploits a two-level topic model that includes the citation information for ‘father' topics and text information for sub-topics. The model parameters are estimated by a collapsed Gibbs sampling algorithm. We also propose a topic evolution algorithm that runs in two steps: topic segmentation and topic dependency relation calculation. We have tested the proposed citation-content-LDA model and topic evolution algorithm on two online datasets, IEEE Transactions on Pattern Analysis and Machine Intelligence(PAMI) and IEEE Computer Society(CS), to demonstrate that our algorithm effectively discovers important topics and reflects the topic evolution of important research themes. According to our evaluation metrics, citation-content-LDA outperforms both content-LDA and citation-LDA.

关键词： Topic extraction Topic evolution Evaluation method

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The Perception of Flood Risks: A Case Study of Babessi in Rural Cameroon

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International Journal of Disaster Risk Science 2021年第4期12卷 458-478页

作者： Gertrud Buchenrieder Julian Brandl Azibo roland Balgah Research Center RISK Institute of Sociology and EconomicsUniversität der Bundeswehr München85577NeubibergGermany Leibniz Institute of Agricultural Development in Transition Economies(IAMO) 06120Halle(Saale)Germany TUM School of Life Sciences Weihenstephan Technical University Munich(TUM)85354MunichGermany College of Technology The University of Bamenda(UBa)BamendaNorth West RegionCameroon

Although risk perception of natural hazards has been identified as an important determinant for sound policy design,there is limited empirical research on it in developing *** article narrows the empirical literature *** draws from Babessi,a rural town in the Northwest Region of *** was hit by a severe flash flood in *** cross-disciplinary lens applied here deciphers the complexity arising from flood hazards,often embedded in contexts characterized by poverty,a state that is constrained in disaster relief,and market-based solutions being *** data were collected via snowball *** logistic regression analysis suggests that individuals with leadership functions,for example,heads of households,perceive flood risk higher,probably due to their role as household *** found that risk perception is linked to location,which in turn is associated with religious *** perceive floods riskier than Muslims because the former traditionally reside at the foot of hills and the latter uphill;rendering Muslims less exposed and eventually less affected by ***,public disaster relief appears to have built up trust and subsequently reduced risk perception,even if some victims remained skeptical of state disaster *** indicates strong potential benefits of public transfers for flood risk management in developing countries.

关键词： Flood disaster Multinomial logistic regression Risk perception Rural Cameroon

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Heat Treatment and Properties of Nitrogen Alloyed, Martensitic, Corrosion-resistant Steels

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材料热处理学报 2004年第5期25卷 582-587页

作者： Reinhold Schneider Klaus Sammt roland Rabitsch Michael Haspel BOHLER Edelstahl GmbH Kapfenberg Austria

This paper gives a short introduction to the typical process route and material properties of these steels in comparison to standard martensitic corrosion-resistant steels. The typical response of these steels to various heat treatment parameters is shown and explained using the three grades M333, N360 and M340 (all made by Bohler Edelstahl GmbH) as examples, and the physical metallurgy of these steels and its consequences for practical heat treatment is explained. The correlation between tempering parameters and their effect on the toughness and corrosion properties is explained in particular detail, showing that these new steels not only offer far better property combinations under the usual heat treatment parameters than standard martensitic corrosion-resistant steels, but that they also open the door to extending heat treatment combinations and properties.

关键词：热处理高氮钢马氏体钢抗腐蚀钢

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Single-port versus multi-port cholecystectomy for patients with acute cholecystitis: a retrospective comparative analysis

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Hepatobiliary & Pancreatic Diseases International 2011年第5期10卷 521-525页

作者： Dietmar Jacob roland Raakow Department of Surgery Center for Minimally Invasive Surgery Vivantes Hospital Spandau Neue Bergstrasse 6 13585 Berlin Germany Department of Surgery Vivantes Klinikum Am Urban Dieffenbachstrasse 1 10967 Berlin Germany

BACKGROUND: Trans-umbilical single-port laparoscopic cholecystectomy for chronic gallbladder disease is becoming increasingly accepted worldwide. But so far, no reports exist about the challenging single-port surgery for acute cholecystitis. The objective of this study was to describe our experience with single-port cholecystectomy in comparison to the conventional laparoscopic technique. METHODS: Between August 2008 and March 2010, 73 patients with symptomatic gallbladder disease and histopathological signs of acute cholecystitis underwent laparoscopic cholecystec- tomy at our institution. Thirty-six patients were operated on with the single-port technique (SP group) and the data were compared with a control group of 37 patients who were treated with the multi-port technique (MP group). RESULTS: The mean age in the SP group was 61.5 (range 21-81) years and in the MP group was 60 (range 21-94) (P=0.712). Gender, ASA status and BMI were not significantly different. The number of white blood cells was different before [SP: 9.2 (range 2.8-78.4); MP: 13.2 (range 4.4-28.6); P=0.001] and after the operation [SP: 7.8 (range 3.5-184.8); MP: 11.1 (range 5-20.8); P=0.002]. Mean operating time was 88 (range 34-174) minutes in the SP group vs 94 (range 39-209) minutes in the MP group (P=0.147). Four patients (5%) required conversion to an open procedure (SP: 1; MP: 3; P=0.320). During the follow- up period of 332 (range 29-570) days in the SP group and 428 (range 111-619) days in the MP group (P=0.044), eleven (15%) patients developed postoperative complications (P=0.745) and two patients in the SP group required reoperation (P=0.154). CONCLUSIONS: Trans-umbilical single-port cholecystectomy for beginning acute cholecystitis is feasible and the complicationrate is comparable with the standard multi-port operation. In spite of our good results, these operations are difficult to perform and should only be done in high-volume centers for laparoscopic surgery with experience in sin

关键词： laparoscopic surgery single-port cholecystectomy acute cholecystitis

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Rendering algorithms for aberrated human vision simulation

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Visual Computing for Industry,Biomedicine,and Art 2023年第1期6卷 51-75页

作者： István Csoba roland Kunkli Faculty of Informatics University of DebrecenDebrecen 4028Hungary Doctoral School of Informatics University of DebrecenDebrecen 4028Hungary

Vision-simulated imagery―the process of generating images that mimic the human visual system―is a valuable tool with a wide spectrum of possible applications, including visual acuity measurements, personalized planning of corrective lenses and surgeries, vision-correcting displays, vision-related hardware development, and extended reality discomfort reduction. A critical property of human vision is that it is imperfect because of the highly influential wavefront aberrations that vary from person to person. This study provides an overview of the existing computational image generation techniques that properly simulate human vision in the presence of wavefront aberrations. These algorithms typically apply ray tracing with a detailed description of the simulated eye or utilize the point-spread func-tion of the eye to perform convolution on the input image. Based on the description of the vision simulation tech-niques, several of their characteristic features have been evaluated and some potential application areas and research directions have been outlined.

关键词： Human vision Human visual system Vision simulation Wavefront aberrations Visual aberrations Vision-realistic rendering

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A Truncated Marxism:On the Ideological Structure of Western Marxism

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Fudan Journal of the Humanities and Social Sciences 2023年第2期16卷 145-170页

作者： roland Boer School of Philosophy Renmin University of China59 Zhongguancun StreetHaidian DistrictBeijing100872China

This study presents an overview of the ideological framework of“Western Marxism.”This framework has a number of components,which are described in terms of a series of reductions,determinations,and the suspicions entertained by Western *** result was a truncated type of Marxism that cut itself off from the Marxist–Leninist *** did so by reducing Marxism to the works of Marx alone and calling this“historical materialism,”which entailed a rejection of Engels’s significant contributions in history,science,and theory,and thus entailed a rejection of the subsequent developments of *** Western Marxism has been primarily promoted by“freelance intellectuals”with virtually no connection to Workers’or Communist Parties and was determined by an assumed ideological position before a proletarian revolution,was shaped by Western liberalism and imperialism,and has been constantly tempted into religiously inspired utopian versions of *** deep suspicions of the state and national liberation,of science and technology,and of the importance of productive forces,this Western Marxism was always hoping for the ideal revolution(or even better,a peaceful transition)that would very quickly produce a utopian socialist society organised only by the people and without a *** ideological framework also entailed a dismissal of the actual experience in developing countries of successful proletarian revolutions and the construction of socialism.

关键词： Western Marxism Ideological structure Reductions Determinations Suspicions

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The End of Western Marxism?On the Unravelling of an Ideological Structure

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Fudan Journal of the Humanities and Social Sciences 2023年第2期16卷 123-143页

作者： roland Boer School of Philosophy Renmin University of China59 Zhongguancun StreetHaidian DistrictBeijing100872China

This study examines the proposition that the ideological structure of“Western Marxism”began to unravel after 1989 and the end of the Cold War,and that it is now largely falling *** argument proceeds in three steps,the first of which is an overview of Western Marxism’s ideological *** second step analyses a number of deeply critical assessments of Western Marxism from within the contexts of the few countries of the world that make up the“West.”The fact that these critical and often polemical studies are appearing indicates the breakdown of Western Marxism’s former *** third step deals with more constructive material,including the Western“recovery”of Engels,and especially the dialectics of nature,as well as the impact of the major achievements in the theory and practice of Marxism from developing countries,in the context of socialism in power.

关键词： Western Marxism Ideological structure Cold War context Criticism Recovering the full Marxist tradition

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On the Numerical Solution of Some Eikonal Equations:An Elliptic Solver Approach

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Chinese Annals of Mathematics,Series B 2015年第5期36卷 689-702页

作者： Alexandre CABOUSSAT roland GLOWINSKI Tsorng-Whay PAN Haute Ecole de Gestion de Genève University of Applied Sciences Department of Mathematics University of Houston

The steady Eikonal equation is a prototypical first-order fully nonlinear equation. A numerical method based on elliptic solvers is presented here to solve two different kinds of steady Eikonal equations and compute solutions, which are maximal and minimal in the variational sense. The approach in this paper relies on a variational argument involving penalty, a biharmonic regularization, and an operator-splitting-based time-discretization scheme for the solution of an associated initial-value problem. This approach allows the decoupling of the nonlinearities and differential *** experiments are performed to validate this approach and investigate its convergence properties from a numerical viewpoint.

关键词： Eikonal equations Maximal solutions Regularization methods Operator slalitting Finite element methods

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Probabilistic hypergraph based hash codes for social image search

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第7期15卷 537-550页

作者： Yi XIE Hui-min YU roland HU Department of Information Science and Electronic Engineering Zhejiang University

With the rapid development of the Internet, recent years have seen the explosive growth of social media. This brings great challenges in performing efficient and accurate image retrieval on a large scale. Recent work shows that using hashing methods to embed high-dimensional image features and tag information into Hamming space provides a powerful way to index large collections of social images. By learning hash codes through a spectral graph partitioning algorithm, spectral hashing(SH) has shown promising performance among various hashing approaches. However, it is incomplete to model the relations among images only by pairwise simple graphs which ignore the relationship in a higher order. In this paper, we utilize a probabilistic hypergraph model to learn hash codes for social image retrieval. A probabilistic hypergraph model offers a higher order repre-sentation among social images by connecting more than two images in one hyperedge. Unlike a normal hypergraph model, a probabilistic hypergraph model considers not only the grouping information, but also the similarities between vertices in hy-peredges. Experiments on Flickr image datasets verify the performance of our proposed approach.

关键词： Hypergraph Laplacian Probabilistic hypergraph Hash codes Image search

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