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Numerical modelling of a turbulent bluff-body flow with Reynolds stress turbulent models

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Progress in Natural Science:Materials International 2005年第5期15卷 458-462页

作者： dirk ROEKAERTS CJ2628 Delft Delft University of Technology Department of Applied Physics The Netherlands

Numerical modelling of a turbulent bluff-body flow has been performed using differential Reynolds stress models (DRSMs). To clarify the applicability of the existing DRSMs in this complex flow, several typical DRSMs, including LRR-IP model, JM model, SSG model, as well as a modified LRR-IP model, have been validated and evaluated. The performance difference between various DRSMs is quite significant. Most of the above mentioned DRSMs cannot provide overall satisfactory predictions for this challenging test case. Motivated by the deficiency of the existing approaches, a new modification of LRR-IP model has been proposed. A very significant improvement of the prediction of flow field is obtained.

关键词： bluff-body flow differential Reynolds stress models turbulent model.

Phosphorus release from vivianite and hydroxyapatite by organic and inorganic compounds

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Pedosphere 2020年第2期30卷 190-200页

作者： Stella GYPSER dirk FREESE Brandenburg University of Technology Cottbus-Senftenberg Faculty of EnvironmentProcess EngineeringBiotechnology and ChemistryDepartment of Soil Protection and RecultivationKonrad-Wachsmann-Allee 6Cottbus 03046Germany

Based on recent mining rates and the exhaustion of global phosphorus(P)reserves,there is a need to mobilize P already stored in soils,and its recovery from secondary resources such as Ca-and Fe-phosphates is *** Ca-phosphate hydroxyapatite forms a good fertilizer source,while vivianite is formed in waterlogged soils and *** sludge treatment,the formation of vivianite has been identified,being mainly ***-term P release from both hydroxyapatite and vivianite was studied using different inorganic(CaCl2 and CaSO4)and organic(citric and humic acid)reagents during batch *** CaCl2 and CaSO4 represent the soil solution,while citric and humic acids as organic constituents affect P availability in the rhizosphere and during the process of ***,the flow-through reactor(FTR)technique with an infinite sink was used to study the long-term P release *** cumulative P release was higher by organic acids than by inorganic *** cumulative P release rates were higher in the FTR with CaCl2 as compared to the batch *** infinite sink application caused a continuously high concentration gradient between the solid and liquid phases,leading to higher desorption rates as compared to the batch *** predominant amount of the total P released over time was available for a short *** inorganic anion exchange occurred at easily available binding sites,organic acids affected the more heavily available binding sites,which could be embedded within the mineral *** results showed that organic compounds,especially citric acid,play a superior role as compared to the inorganic constituents of the soil solution during the recovery of already stored P from the tertiary phosphates vivianite and hydroxyapatite.

关键词： anion exchange batch technique citric acid flow-through reactor humic acid ligand exchange phosphate phosphorus recovery

Utilization of fly ash from coal-fired power plants in China

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第5期9卷 681-687页

作者： Eva SELIC Jan-dirk HERBELL Waste Management Engineering Department of Mechanical Engineering University of Duisburg-Essen Duisburg 47057 Germany

The rapidly increasing demand for energy in China leads to the construction of new power plants all over the country. Coal, as the main fuel resource of those power plants, results in increasing problems with the disposal of solid residues from combustion and off gas cleaning. This investigation describes chances for the utilization of fly ash from coal-fired power plants in China. After briefly comparing the situation in China and Germany, the status of aluminum recycling from fly ash and the ad- vantages for using fly ash in concrete products are introduced. Chemical and physical analyses of Chinese fly ash samples, e.g., X-ray diffraction (XRD), ICP (Inductive Coupled Plasma) and particle size analysis, water requirement, etc. are presented. Rea- sonable amounts of aluminum were detected in the samples under investigation, but for recovery only sophisticated procedures are available up to now. Therefore, simpler techniques are suggested for the first steps in the utilization of Chinese fly ash.

关键词： Fly ash utilization Aluminum recycling Concrete Chemical and physical analyses

Hazard Rate Estimation for GNSS-Based Train Localization Using Model-Based Approach

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Chinese Journal of Electronics 2020年第1期29卷 49-56页

作者： LU Debiao TANG Dezhang SPIEGEL dirk Beijing Engineering Research Center of EMC and GNSS Technology for Rail Transportation School of Electronic and Information Engineering Beijing Jiaotong University Deutsche Bahn AG Bahntower

GNSS(Global navigation satellite system)has shown its ability on the non-safety relevant applications in various applications. In railway domain, safety is the utmost concern, GNSS-based train localization unit is the carrier of safe localization. EN 50126 standard specifies the electric and electronic system performance requirements as Reliability, availability, maintainability and safety(RAMS). Safety performance characteristic is based on the reliability and availability analysis *** formal method considering the risk identification and analysis is compulsory for the safety assessment. This paper provides the method for hazard analysis of the GNSS-based train localization function and further the hazard rate estimation of each hazard. The model-based approach using GNSS localization unit working principle is proposed to study railway localization behavior *** hazard for the localization unit is formally stated, real collected data on circular test track in Beijing is studied using the proposed method. The result shows that the safety requirement of the performance can be transformed into safety integrity properly, the risks of GNSS in train station environment conditions are presented.

关键词： Tolerable hazard rate GNSS Risk analysis Train localization

mmunological functions of liver sinusoida endothelial cells

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Cellular & Molecular Immunology 2016年第3期13卷 347-353页

作者： Percy A Knolle dirk Wohlleber Institute of Molecular Immunology and Experimental Oncology Klinikum Munchen rechts der Isar Technische Universitat Munchen Munchen 81675 Germany Institute of Experimental Immunology Universitatsklinikum Bonn Universitat Bonn Bonn Germany

Liver sinusoidal endothelial cells （LSECs） line the liver sinusoids and separate passenger leukocytes in the sinusoidal lumen from hepatocytes. LSECs further act as a platform for adhesion of various liver-resident immune cell populations such as Kupffer cells, innate lymphoid cells or liver dendritic cells. In addition to having an extraordinary scavenger function, LSECs possess potent immune functions, serving as sentinel cells to detect microbial infection through pattern recognition receptor activation and as antigen （cross）-presenting cells. LSECs cross-prime naive CD8 T cells, causing their rapid differentiation into memory T cells that relocate to secondary lymphoid tissues and provide protection when they re-encounter the antigen during microbial infection. Cross-presentation of viral antigens by LSECs derived from infected hepatocytes triggers local activation of effector CD8 T cells and thereby assures hepatic immune surveillance. The immune function of LSECs complements conventional immune-activating mechanisms to accommodate optimal immune surveillance against infectious microorganisms while preserving the integrity of the liver as a metabolic organ.

关键词： CD8 T cells cross-presentation liver LSEC

Membrane-destabilizing ionizable phospholipids: Novel components for organ-selective mRNA delivery and CRISPR-Cas gene editing

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Signal Transduction and Targeted Therapy 2021年第6期6卷 1643-1645页

作者： Ning Meng dirk Grimm Department of Infectious Diseases/Virology Medical FacultyUniversity of HeidelbergHeidelbergGermany BioQuant University of HeidelbergHeidelbergGermany German Center for Infection Research(DZIF)and German Center for Cardiovascular Research(DZHK) partner site HeidelbergHeidelbergGermany

In a new study published in Nature Materials,Liu et al.1 report a novel design of lipid nanoparticles(LNPs)in which multi-tailed ionizable phospholipids(iPhos)constitute the active component,and which facilitates endosomal escape and thus improves delivery of mRNA and/or single-guide(sg)RNA for in vivo gene *** composed of the best-performing iPhos and different helper lipids_zwitterionic lipids,ionizable cationic lipids and permanently cationic lipids-achieved selective organ targeting(SORT)and organ-specific CRISPR-Cas9 gene editing in spleen,liver,and lungs of mice,respectively.

关键词： spleen editing cationic

Authigenic gypsum found in gas hydrate-associated sediments from Hydrate Ridge, the eastern North Pacific

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Science China Earth Sciences 2004年第3期47卷 280-288页

作者： Erwin Suess dirk Rickert Department of Marine Environmental Geology Research Centre of Marine Geology University of Kiel Kiel D-24148 Germany Department of Marine Environmental Geology Research Centre of Marine Geology University of Kiel Kiel D-24148 Germany

Characteristic gypsum micro-sphere and granular mass were discovered by bin-ocular microscope in the gas hydrate-associated sediments at cores SO143-221 and SO143/TVG40-2A respectively on Hydrate Ridge of Cascadia margin, the eastern North Pacific. XRD patterns and EPA analyses show both micro-sphere and granular mass of the crystals have the typical peaks and the typical main chemical compositions of gypsum, although their weight percents are slightly less than the others in the non-gas hydrate-associated marine regions. SEM pictures show that the gypsum crystals have clear crystal boundaries, planes, edges and cleav-ages of gypsum in form either of single crystal or of twin crystals. In view of the fact that there are meanwhile gas hydrate-associated authigenic carbonates and SO42--rich pore water in the same sediment cores, it could be inferred reasonably that the gypsums formed also authigenically in the gas hydrate-associated environment too, most probably at the interface between the down-ward advecting sulfate-rich seawater and the below gas hydrate, which spilled calcium during its formation on Hydrate Ridge. The two distinct forms of crystal intergrowth, which are the granular mass of series single gypsum crystals at core SO143/TVG40-2A and the microsphere of gypsum crystals accompanied with detrital components at core SO143-221 respectively, indicate that they precipitated most likely in different interstitial water dynamic environments. So, the distinct authigenic gypsums found in gas hydrate-associated sediments on Hydrate Ridge could also be believed as one of the parameters which could be used to indicate the presence of gas hydrate in an unknown marine sediment cores.

关键词： authigenic gypsum, gas hydrate-associated sediment, Hydrate Ridge, eastern North Pacific.

Detoxification of ferrocyanide in a soil–plant system

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Journal of Environmental Sciences 2019年第3期31卷 54-64页

作者： Tsvetelina Dimitrova Frank Repmann dirk Freese Brandenburg University of Technology Cottbus-Senftenberg

The detoxification of iron cyanide in a soil–plant system was investigated to assess the total cyanide extracted from contaminated soil and allocated in the leaf tissue of willow trees(Salix caprea). They were grown in soil containing up to 1000 mg/kg dry weight(dw) of cyanide(CN),added as ^(15)N-labeled potassium ferrocyanide and prepared with a new method for synthesis of labeled iron cyanides. CN content and ^(15)N enrichment were monitored weekly over the exposure in leaf tissue of different age. The ^(15)N enrichment in the young and old leaf tissue reached up to 15.197‰ and 9063‰, respectively; it increased significantly over the exposure and with increasing exposure concentrations(p < 0.05). Although the CN accumulation in the old leaf tissue was higher, compared to the young leaf tissue(p < 0.05), the ^(15)N enrichment in the two tissue types did not differ statistically. This indicates a non-uniform CN accumulation but a uniform ^(15)N allocation throughout the leaf mass. Significant differences were detected between the measured CN content and the C^(15)N content, calculated from the ^(15)N enrichment(p < 0.05), revealing a significant CN fraction within the leaf tissue, which could not be detected as ionic CN. The application of labeled iron CN clearly shows that CN is detoxified during uptake by the willows. However, these results do not exclude other detoxification pathways, not related to the trees. Still, they are strongly indicative of the central role the trees played in CN removal and detoxification under the experimental conditions.

关键词： Iron cyanide Detoxification Exposure Phytoremediation

Deep Drawing with Local Hardening on Digital Multi-axis Servo Press

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Acta Metallurgica Sinica(English Letters) 2015年第12期28卷 1490-1495页

作者： Sebastian Kriechenbauer Reinhard Mauermann dirk Landgrebe Fraunhofer IWU

The paper discusses a new drawing technology, based on a synchronized movement of ram and cushion with multiple bending operations in alternating directions called ＂bi-directional deep drawing（BDD）.＂ The goal is to avoid local thinning by strengthening the weak point using local hardening. BDD operations are realized before the conventional deep drawing process. This results in a local strain hardening at the weak point of the workpiece, which is usually located at the bottom punch radius. Two major aspects have to be given attention due to the high number of process parameters. On the one hand, for process design, it is helpful to have a tool by means of which it is possible to simultaneously create both the machine program for the servo press and the initial configuration for the process simulation. From the authors＇ point of view, this complexity can only be represented by a numerical analysis method, on the other hand. Consequently, both aspects are given attention in this paper.

关键词： Bi-directional deep drawing(BDD) Local hardening Servo press Pulsation