检索结果-南通市图书馆

Reactive gas-solids flows in large volumes—3D modeling of industrial circulating fluidized bed combustors

在线全文

学校读者我要写书评

暂无评论

Particuology 2010年第1期8卷 67-77页

作者： Reiner Wischnewski lars Ratschow Ernst-Ulrich Hartge Joachim Werther Hydro Aluminium AS Pyry Energy GmbH Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology

A model is presented for the simulation of reactive gas-solids flows in large industrial reactors. Circulating fluidized bed （CFB） combustors with several thousands of cubic meters reaction volume are probably the largest reactors of this type. A semi-empirical modeling approach has been chosen to model the three-dimensional concentration distributions of gas and solids components and temperatures inside the combustion chamber of such boilers. Two industrial CFB boilers are investigated in detail： the 105 MWe Duisburg combustor in Germany and the 235 MWe Turow combustor in Poland. The semi-empirical model approach is described first. Then the model is used to show how the three-dimensional concentration and temperature fields are formed by the interaction of several local phenomena. Good agreement between simulation and measurements has been achieved.

关键词： Circulating fluidized bed Large-scale Combustion 3D modeling

Route, origin & valence matter: towards sophisticated nextgeneration vaccines to cope with the CoVID-19 pandemic

在线全文

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2022年第7期7卷 2123-2125页

作者： Julia Volckmar lars Melcher Dunja Bruder Infection Immunology Group Institute of Medical MicrobiologyInfection Prevention and ControlHealth Campus ImmunologyInfectiology and InflammationOtto-vonGuericke University MagdeburgMagdeburgGermany Immune Regulation Group Helmholtz Centre for Infection ResearchBraunschweigGermany

In a recent study published in Cell,Afkhami and colleagues systematically compared different routes of vaccine delivery,origin of the vaccine platform as well as valence of the vaccine and demonstrated that the respiratory mucosal delivery of a trivalent chimpanzee’s adenovirus(Ad)-vectored vaccine is superior to any other of the tested conditions in inducing broadlyacting immunity and protection against current severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)and possibly future variants of concern(VoC).1 The ongoing global coronavirus disease 2019(CoVID-19)pandemic caused by SARS-CoV-2 has forced an uniquely fast development of novel mRNA-and vector-based vaccines.

关键词： vaccine vaccines immunity

Simulation-supported measurements in large circulating fluidized bed combustors

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2009年第4期7卷 324-331页

作者： Joachim Werther Ernst-Ulrich Hartge lars Ratschow Reiner Wischnewski Institute of Solids Process Engineering and Particle Technology Hamburg University of TechnologyD 21071 HamburgGermany Now with Pyry Energy GmbH HamburgGermany Now with Hydro Aluminium AS OsloNorway

The concept of simulation-supported measurement is suggested for the elucidation of processes occurring in the combustion chambers of large-scale circulating fluidized bed combustors where the desired information cannot be obtained by direct measurements. The concept is illustrated with the example of secondary air injection where the way the air is released, the penetration depth and the evenness of air distribution over the cross-sectional area of the combustion chamber are of interest. The measured information consists of lateral profiles of oxygen concentrations measured with gas sampling probes at two ports which were located 5 and 9 m, respectively, above the level of secondary air injection. The simulation is carried out on the basis of a 3D semi-empirical fluid-mechanical model of the circulating fluidized bed which is combined with models of gas and solids mixing, fuel distribution, devolatilization and combustion of char and volatiles. The combination of the simulation with the measurements yields a clear picture of the mechanism of secondary air injection, its penetration into the combustion chamber and its effect on the local combustion processes. The results confirm the usefulness of the concept of simulation-supported measurement for this application.

关键词： Fluidized bed Combustion Local measurements 3D modeling

Diversity-accuracy assessment of multiple classifier systems for the land cover classification of the Khumbu region in the Himalayas

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2022年第2期19卷 365-387页

作者： Charisse Camacho HANSoN lars BRABYN Sher Bahadur GURUNG Geography Programme University of WaikatoPrivate Bag 3105Hamilton 3240New Zealand Central Department of Geography Tribhuvan UniversityTU RdKirtipur 44618Nepal

Land cover classification of mountainous environments continues to be a challenging remote sensing problem,owing to landscape complexities exhibited by the *** study explored a multiple classifier system(MCS)approach to the classification of mountain land cover for the Khumbu region in the Himalayas using Sentinel-2 images and a cloud-based model *** relationship between classification accuracy and MCS diversity was investigated,and the effects of different diversification and combination methods on MCS classification performance were comparatively assessed for this *** present ten MCS models that implement a homogeneous ensemble approach,using the high performing Random Forest(RF)algorithm as the selected *** base classifiers of each MCS model were developed using different combinations of three diversity techniques:(1)distinct training sets,(2)Mean Decrease Accuracy feature selection,and(3)‘one-vs-All’problem *** base classifier predictions of each RFMCS model were combined using:(1)majority vote,(2)weighted argmax,and(3)a meta RF *** MCS models reported higher classification accuracies than the benchmark classifier(overall accuracy with 95% confidence interval:87.33%±0.97%),with the highest performing model reporting an overall accuracy(±95% confidence interval)of 90.95%±0.84%.our key findings include:(1)MCS is effective in mountainous environments prone to noise from landscape complexities,(2)problem reduction is indicated as a stronger method over feature selection in improving the diversity of the MCS,(3)although the MCS diversity and accuracy have a positive correlation,our results suggest this is a weak relationship for mountainous classifications,and(4)the selected diversity methods improve the discriminability of MCS against vegetation and forest classes in mountainous land cover classifications and exhibit a cumulative effect on MCS diversity for this context.

关键词： Multiple classifier system Ensemble diversity Google Earth Engine Land Cover Classification Himalayas Random Forest

CFD-simulation of a circulating fluidized bed riser

在线全文

学校读者我要写书评

暂无评论

Particuology 2009年第4期7卷 283-296页

作者： Ernst-Ulrich Hartge lars Ratschow Reiner Wischnewski Joachim Werther Hamburg-University of Technology Institute of Solids Process Engineering and Particle TechnologyD-21071 HamburgGermany

In the current work, a model of the fluid mechanics in the riser of a circulating fluidized bed （CFB） has been implemented using computational fluid dynamics （CFD）. The model developed shall be used in future as the basis of 3D-reactor model for the simulation of large scale CFB combustors. The two-fluid model （TFM） approach is used to represent the fluid mechanics involved in the flow. The computational implementation is accomplished by the commercial software FLUENT. Different closure formulations are tested on a simplified geometry. Two different turbulence formulations, namely the swirl modified RNG k-e model and the Realizable k-e model, are tested in combination with two different approaches to solid phase turbulence, namely the dispersion and per phase approach. one focus of the current work is put on the study of different drag correlations. Besides the drag correlations by Syamlal et al. [Syamlal, M., Rogers, W., ＆ o＇Brien, T. J. （1993）. MFIX documentation theory guide. Technical Report DoE/METC-9411004, U.S. Department of Energy （DoE）. Morgantown Energy Technology Center： Morgantown, WV] and Gidaspow [Gidaspow, D. （1994）. Multiphaseflow andfluidization. New York： Academic Press] the EMMS model has been used to determine the momentum exchange between the two phases. The resulting formulation is then used to simulate a 1-m × 0.3-m cold CFB setup and is validated by experimental results [Schlichtharle, P. （2000）. Fluid dynamics and mixing of solids and gas in the bottom zone of circulating fluidized beds. Unoublished doctoral dissertation, Technische Universitaet Hamburg-Harburg, Shaker Verlag： Aachen].

关键词： Circulating fluidized bed Two-fuid model EMMS model Drag correlations

Intraoperative cholangiography 2020:Quo vadis? A systematic review of the literature

在线全文

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2022年第2期21卷 145-153页

作者： Konstantinos Georgiou Gabriel Sandblom Nicholas Alexakis lars Enochsson First Department of Propaedeutic Surgery Hippokration General Hospital of AthensAthens Medical SchoolNational and Kapodistrian University of AthensAthens 10679Greece Department of Clinical Science and Education Department of SurgeryKarolinska InstitutetSödersjukhusetStockholm 17177SESweden Department of Surgical and Perioperative Sciences SurgeryUmeåUniversityUmeå90187SESweden

Background: There are few randomized controlled trials with sufficient statistical power to assess the effectiveness of intraoperative cholangiography(IoC) in the detection and treatment of common bile duct injury(BDI) or retained stones during cholecystectomy. The best evidence so far regarding IoC and reduced morbidity related to BDI and retained common bile duct stones was derived from large populationbased cohort studies. Population-based studies also have the advantage of reflecting the outcome of the procedure as it is practiced in the community at large. However, the outcomes of these population-based studies are conflicting. Data sources: A systematic literature search was conducted in 2020 to search for articles that contained the terms “bile duct injury”, “critical view of safety”, “bile duct imaging” or “retained stones” in combination with IoC. All identifed references were screened to select population-based studies and observational studies from large centers where socioeconomic or geographical selections were assumed not to cause selection bias. Results: The search revealed 273 references. A total of 30 articles fulflled the criteria for a large observational study with minimal risk for selection bias. The majority suggested that IoC reduces morbidity associated with BDI and retained common bile duct stones. In the short term, IoC increases the cost of surgery. However, this is offset by reduced costs in the long run since BDI or retained stones detected during surgery are managed immediately. Conclusions: IoC reduces morbidity associated with BDI and retained common bile duct stones. The reports reviewed are derived from large, unselected populations, thereby providing a high external validity. However, more studies on routine and selective IoC with well-defned outcome measures and sufficient statistical power are needed.

关键词： Cholangiography Cholecystectomy Bile duct stones Bile duct injury Cost

Hydrodynamic Performance of A Porous-Type Land-Fixed oscillating Water Column Wave Energy Converter

在线全文

学校读者我要写书评

暂无评论

China ocean Engineering 2022年第1期36卷 1-14页

作者： Robert MAYoN NING De-zhi ZHANG Chong-wei lars JoHANNING State Key Laboratory of Coastal and offshore Engineering Dalian University of TechnologyDalian 116024China College of Engineering Mathematics and Physical SciencesUniversity of ExeterPenryn CampusPenrynCornwallTR109FEUK

A hybrid, porous breakwater-oscillating Water Column(oWC) Wave Energy Converter(WEC) system is put forward and its hydrodynamic performance is investigated using the fully nonlinear, open-source computational fluid dynamics(CFD) model, openFoAM. The permeable structure is positioned at the weather side of the oWC device and adjoined to its front wall. A numerical modelling approach is employed in which the interstices within the porous structure are explicitly defined. This permits the flow field development within the porous structure and at the oWC front wall to be observed. The WEC device is defined as a land-fixed, semi-submerged oWC chamber. A range of regular incident waves are generated at the inlet within the numerical tank. The oWC efficiency and the forces on the structure are examined. Results are compared for the simulation cases in which the porous component is present or absent in front of the oWC chamber. It is found that the incorporation of the porous component has minimal effect on the hydrodynamic efficiency of the oWC, reducing the efficiency by less than 5%. Nevertheless,the forces on the front wall of the oWC can be reduced by up to 20% at the higher wave steepness investigated,through inclusion of the porous structure at the oWC front wall. These findings have considerable implications for the design of hybrid oWC-breakwater systems, most importantly in terms of enhancing the durability and survivability of oWC WECs without significant loss of operational efficiency.

关键词： oWC porous breakwater hydrodynamic performance wave loads CFD

Diabetes, its impact on peripheral nerve regeneration： lessons from pre-clinical rat models towards nerve repair and reconstruction

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2018年第1期13卷 65-66页

作者： Kirsten Haastert-Talini lars B. Dahlin Institute of Neuroanatomy and Cell Biology Hannover Medical School Hannover Germany Center for Systems Neuroscience (ZSN) Hannover Germany Department of Translational Medicine-Hand Surgery Lund University Lund Sweden Department of Hand Surgery Skane University Hospital Malmo Sweden

The global number of patients with type 1 and type 2 diabetes is about to increase substantially in the coming decades. The reasons for this are two-fold, at first there is actual increase in incidence of type 1 diabetes and at second there is global increase in living expectancy and a high prevalence of patients with type 2 diabetes among the elderly. The diabetic condition is affiliated with reduced peripheral nervous system maintenance, such as peripheral neuropathies （Juster-Switlyk and Smith, 2016） that may be more common in men.

关键词： Diabetes length

Systematic review:Laparoscopic fundoplication for gastroesophageal reflux disease in partial responders to proton pump inhibitors

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2014年第3期20卷 804-813页

作者： lars Lundell Martin Bell Magnus Ruth Department of Surgery CLINTEC Karolinska Institutet Research Evaluation Unit Oxford PharmaGenesisTM Ltd.OxfordOX13 5QJUnited Kingdom Shire-Movetis NV B-2300 TurnhoutBelgium

AIM: To assess laparoscopic fundoplication (LF) in partial responders to proton pump inhibitors (PPIs) for gastroesophageal reflux disease (GERD).

关键词： Laparoscopic fundoplication Gastroesophageal reflux disease Partial response Proton pump inhibitors Systematic review