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Simulation and calibration of granules using the discrete element method

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Particuology 2014年第1期12卷 40-43页

作者： Peter Müller jürgen Tomas Institute of Process Engineering Mechanical Process EngineeringOtto-von-Guericke University MagdeburgUniversitätsplatz 239106 MagdeburgGermany

The discrete element method （DEM）, developed by Cundall and 5track to solve geomecnamcai problems, is used to simulate the mechanical behavior of granules. According to the DEM, an individ ual granule can be modeled as a realistic mechanical system consisting of primary particles bonded by interaction forces. Cranulometric properties of the model material, zeolite 4A, have been measured to determine their macro properties. To investigate the compression behavior, a compression test was performed using a strength tester on single granules between two pistons. A modeled granule consisting of more than 22,000 primary particles was generated. The micro properties of the modeled granule have been precisely set to allow its macro properties to be equivalent to the macro properties of zeolite 4A granules. To calibrate the mechanical properties, diametrical compression was simulated using two rigid walls stressed at a constant stressing velocity, The force-displacement curve of the modeled granule at compression has been calibrated by the experimental curve of zeolite 4A.

关键词： Discrete element method Material behavior Granulation

Stakeholder orientated sustainable land management:The Ruhr Area as a role model for urban areas

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International journal of Mining Science and Technology 2013年第5期23卷 659-663页

作者： jürgen Kretschmann University of Applied Sciences TFH Georg Agricola

The concept of sustainable land management(SLM)can help create a balance between the different demands of economy,society and *** means to actively develop land based on a knowledgebased *** should aim on long term *** basis of SLM is the interests and the goals of the *** is the result of a bargaining process between different institutions by creating win-win-situations or adequate conflict solutions to reach a *** Ruhr Area is Germany’s biggest metropolitan *** management regarding economic,social and environmental issues,which has a long tradition in this area,goes back to *** the centre of the heavy industry in Germany for more than 150 years,the Ruhr Area today is a green *** ecological,social and economical change of this industrial region can serve as a role model for SLM in urban areas all over the world.

关键词： Land management Sustainability Mining heritage Ruhr Area

Lignocellulose as an insoluble fiber source in poultry nutrition:a review

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journal of Animal Science and Biotechnology 2021年第4期12卷 1237-1251页

作者： Ilen Röhe jürgen Zentek Department of Veterinary Medicine Institute of Animal NutritionFreie Universität Berlin14195 BerlinGermany

Extensive research in recent years into the use of various fiber sources in poultry nutrition has led to the perception that dietary fiber is more than a simple diet *** studies showed that the feeding of insoluble fiber sources such as oat hulls,sunflower hulls or wood shavings may affect digestive physiology and function improving chickens health and growth *** this context,the effect of lignocellulose as an insoluble dietary fiber source is increasingly being *** is a component of plant cell walls and consists mainly of the insoluble carbohydrate polymers cellulose and hemicelluloses as well as the phenolic polymer *** is chemically and physicochemically different from other insoluble fiber sources and thus possibly has different effects on poultry compared to traditional fiber *** studies investigated the effect of dietary lignocellulose on growth performance,nutrient digestibility,gastrointestinal tract development and intestinal microbiota in broilers and laying *** differed in terms of feed formulation and lignocellulose inclusion level as well as products of different suppliers were *** results obtained are inconsistent;beneficial,indifferent or detrimental effects of feeding lignocellulose were observed,so that a final assessment of lignocellulose as a“novel”insoluble fiber source is *** review article summarizes the results of studies in connection with the feeding of lignocellulose to poultry,compares them with those that have used other insoluble fiber sources and illuminates the possible mechanisms of action.

关键词： Fiber Growth performance Gut health Gut morphology Lignocellulose Microbiota Nutrient digestibility Poultry

The circular dataimage, a graph for high-resolution circular-spatial data

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International journal of Digital Earth 2010年第1期3卷 47-71页

作者： William j.Morpheta jürgen Symanzik ATK Launch Systems Brigham CityUTUSA Department of Mathematics and Statistics Utah State UniversityLoganUTUSA

Vectors and periodic phenomena,*** versus time,have direction on a circular scale of 360°.An overview of existing methods for the display of circularspatial and vectorial-spatial data,such as arrow plots,is *** introduce the circular dataimage,a new type of graphic for the display of circular-spatial *** is defined by encoding direction in a spatial display by using colors from a color wheel constructed by connecting three or more two-color gradients with color continuity at the ***,image discontinuity from using a singlecolor gradient,***-red,does not ***-resolution global views of ocean wind direction are used as a running example throughout the *** and disadvantages of circular dataimages compared to arrow plots were obtained from a usability *** dataimages provide for simultaneous recognition of fine structure on a small-scale and large-scale structure on a global scale.

关键词： digital earth earth observation geo-spatial science geoinformatics visualization

Degenerate slave-makers,but nevertheless slave-makers?Host worker relatedness in the ant Myrmoxenus kraussei

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Integrative Zoology 2015年第2期10卷 182-185页

作者： Masaki SUEFUjI jürgen HEINZE Zoology/Evolutionary Biology University of RegensburgGermany

Socially parasitic ants of the formicoxenine genus Myrmoxenus exhibit considerable diversity in colony structure and life *** some species are active slave-makers with many workers and others are workerless‘murder-parasites,’Myrmoxenus kraussei is considered as a‘degenerate slave-maker’because of its very low worker ***,we document that Temnothorax recedens host workers in single colonies of *** from Lago di Garda,Italy,exhibit significantly more genetic diversity than workers in unparasitized *** raises the possibility that,despite its low worker numbers,*** may actively engage in slave raids in nature.

关键词： dulosis nestmate relatedness Myrmoxenus social parasitism slave-making

Sphincter preservation for distal rectal cancer - a goal worth achieving at all costs?

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World journal of Gastroenterology 2011年第7期17卷 855-861页

作者： jürgen Mulsow Des C Winter Institute for Clinical Outcomes Research and Education St. Vincent’s University Hospital

To assess the merits of currently available treatment options in the management of patients with low rectal cancer, a review of the medical literature pertaining to the operative and non-operative management of low rectal cancer was performed, with particular emphasis on sphincter preservation, oncological outcome, functional outcome, morbidity, quality of life, and patient preference. Low anterior resection (AR) is technically feasible in an increasing proportion of patients with low rectal cancer. The cost of sphincter preservation is the risk of morbidity and poor functional outcome in a significant proportion of patients. Transanal and endoscopic surgery are attractive options in selected patients that can provide satisfactory oncological outcomes while avoiding the morbidity and functional sequelae of open total mesorectal excision. In complete responders to neo-adjuvant chemoradiotherapy, a non-operative approach may prove to be an option. Abdominoperineal excision (APE) imposes a permanent stoma and is associated with significant incidence of perineal morbidity but avoids the risk of poor functional outcome following AR. Quality of life following AR and APE is comparable. Given the choice, most patients will choose AR over APE, however patients following APE positively appraise this option. In striving toward sphincter preservation the challenge is not only to achieve the best possible oncological outcome, but also to ensure that patients with low rectal cancer have realistic and accurate expectations of their treatment choice so that the best possible overall outcome can be obtained by each individual.

关键词： Rectal cancer Survival Local recurrence Morbidity Anorectal function Quality of life Patient preference

Fourth-Order Splitting Methods for Time-Dependant Differential Equations

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Numerical Mathematics(Theory,Methods and Applications) 2008年第3期1卷 321-339页

作者： jürgen Geiser Department of Mathematics Humboldt-Universitt zu BerlinUnter den Linden 6D-10099 BerlinGermany.

This study was suggested by previous work on the simulation of evolution equations with scale-dependent processes,e.g.,wave-propagation or heat-transfer,that are modeled by wave equations or heat ***,we study both parabolic and hyperbolic *** focus on ADI (alternating direction implicit) methods and LOD (locally one-dimensional) methods,which are standard splitting methods of lower order,*** aim is to develop higher-order ADI methods,which are performed by Richardson extrapolation,Crank-Nicolson methods and higher-order LOD methods,based on locally higher-order *** discuss the new theoretical results of the stability and consistency of the ADI *** main idea is to apply a higher- order time discretization and combine it with the ADI *** also discuss the dis- cretization and splitting methods for first-order and second-order evolution equations. The stability analysis is given for the ADI method for first-order time derivatives and for the LOD (locally one-dimensional) methods for second-order time *** higher-order methods are unconditionally *** numerical experiments verify our results.

关键词： Partial differential equations operator-splitting methods evolution equations ADImethods LOD methods stability analysis higher-order methods.

Fixed-time group consensus of second-order multi-agent systems based on event-triggered control

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Chinese Physics B 2023年第7期32卷 329-336页

作者：武肖帅孙凤兰朱伟 jürgen Kurths College of Automation Chongqing University of Posts and TelecommunicationsChongqing 400065China School of Science Chongqing University of Posts and TelecommunicationsChongqing 400065China Department of Complexity Science Potsdam Institute for Climate Impact ResearchPotsdam 14473Germany Institute of Physics Humboldt University of BerlinBerlin 12489Germany

The problem of fixed-time group consensus for second-order multi-agent systems with disturbances is *** cooperative-competitive network,two different control protocols,fixed-time group consensus and fixed-time eventtriggered group consensus,are *** is demonstrated that there is no Zeno behavior under the designed eventtriggered ***,it is proved that for an arbitrary initial state of the system,group consensus within the settling time could be obtained under the proposed control protocols by using matrix analysis and graph ***,a series of numerical examples are propounded to illustrate the performance of the proposed control protocol.

关键词： event-triggered control group consensus multi-agent system fixed-time

Effects of lag time in forest restoration and management

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Forest Ecosystems 2023年第4期10卷 504-515页

作者： Klaus j.Puettmann jürgen Bauhus Department of Forest Ecosystem and Society Oregon State UniversityCorvallisOR97331USA University of Freiburg Tennenbacherstr.479085FreiburgGermany

The increased speed of global change and associated high severity disturbances,in conjunction with the increasing suite of societal expectations on forests,suggest that the timeliness of interventions to encourage the adaptive capacity of ecosystems and to reduce negative impacts in regards to provision of ecosystem services is increasingly *** address this issue,we expand the concept of lag time as used in ecological discussions into a forest management *** this context,lag times have earlier starting and later ending points and can be separated into different *** components include the delay till detection,decision making,and implementation,followed by ecological lag time and the time till ecosystem services are provided at acceptable *** first three components are influenced by the availability of information,the lack of which can extend lag ***,the lengths of components are not simply additive but they *** example,treatment preparation due to a quicker detection can lead to shorter decision and implementation lag *** highlight the benefits of addressing the various components of lag time in forestry *** when considering adaptive capacity in times of global change,our analysis suggests that all aspects of the forestry sector are challenged to consider how to optimize lag ***,we propose that such issues need to be considered with any management action and are especially relevant in discussions whether the best strategy after disturbances or in the light of global change is to adopt a passive approach and let natural ecosystem processes play out on their own or whether active management is better suited to ensure a more rapid and fitting ecosystem response to facilitate the continued provision of ecosystem services.

关键词： Active versus passive restoration Management decisions Global change