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Experimental Setup for the Investigation of Reproducibility of Novel Tool Changing Systems in Nanofabrication Machines

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Nanomanufacturing and Metrology 2021年第3期4卷 181-189页

作者： Florian Weigert Roman Hebenstreit Roland FuBl Rene Theska Institute for Design and Precision Engineering Precision Engineering GroupTechnische Universitat IlmenauGustav-Kirchhoff-Platz.298693 IlmenauGermany Institute for Process Measurement and Sensor Technology Technische Universitat IlmenauGustav-Kirchhoff-Str.198693 IlmenauGermany

Nanomeasuring machines developed at the technische universitat Ilmenau enable three-dimensional measurements and manufacturing processes with the lowest *** to the requirements for these processes,a highly reproducible and long-term stable tool changing system is *** this purpose,kinematically determined couplings are widely *** state-of-the-art investigations on those are not sufficient for the highest demands on the reproducibility required for this application.A theoretical determination of the reproducibility based on analytical or numerical methods is possible,however not in the desired nanometer *** to this,a measurement setup for the determination of the reproducibility in five degrees of freedom with nanometer uncertainty was ***,potential measuring devices are systematically examined and measurement principles were developed out of this.A three-dimensional vector-based uncertainty analysis is performed to prove the feasibility of the measurement principle and provides a basis for further *** a result,a transla-tory measurement uncertainty of 10 nm and a rotatory uncertainty of 11 nrad can be ***,the measurement setup is designed,focusing on the metrological frame and the lift-off *** developed setup exceeds the uncertainties of the measurement setups presented in the state-of-the-art by an order of magnitude,allowing new in-depth investigations of the reproducibility of kinematic couplings.

关键词： Tool changing Kinematic coupling Measurement setup Uncertainty analysis Precision design

Analysis of pneumatic atomizer spray profiles

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Particuology 2016年第6期14卷 80-85页

作者： Walter Schafer Simon Rosenkranz Felix Brinckmann Cameron Tropea AOM-Systems GmbH Flughafenstrasse 15 64347 Griesheim Germany LacTec GmbH Otto-Hahn-Strasse 6-8 63110 Rodgau Germany Institute of Fluid Mechanics and Aerodynamics Technische Universitat Darmstadt Alarich-Weiss-Strasse 10 64287 Darmstadt Germany Graduate School of Computational Engineering Technische Universitat Darmstadt Dolivostrasse 15 64287 Darmstadt Germany

Our objective is to analyze the atomization processes of a pneumatic atomizer by measuring the size and velocity distributions of droplets in a liquid paint spray. The droplet size and velocity distributions have been determined at different axial positions in the spray; a mathematical description of how these quan- tities vary throughout the spray is then proposed. Additionally, the relative number density of droplets and the relative local mass flux are estimated.

关键词： Pneumatic atomizer Spray Measurement Droplet size profile Droplet velocity profile Time-shift

Performance characteristics of the airlift pump under vertical solid-water-gas flow conditions for conveying centimetric-sized coal particles

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International Journal of Coal Science & Technology 2024年第2期11卷 53-66页

作者： Parviz Enany Carsten Drebenshtedt Faculty of Mining and Special Civil Engineering Technische Universitat BergakademieGustav-Zeuner StraBe 1A09599FreibergGermany

In this study,the installation of an airlift pump with inner diameter of 102 mm and length of 5.64 m was utilized to consider the conveying process of non-spherical coal particles with density of 1340 kg/m3 and graining 25-44.5 *** test results revealed that the magnitude of increase in the solid transport rate due to the changes in the three tested parameters between compressed air velocity,submergence ratio,and feeding coal possibility was not the same,which are stand in range of 20%,75%,and 40%,***,creating the optimal airlift pump performance is highly dependent on submergence *** importantly,we measured the solid volume fraction using the method of one-way valves in order to minimize the disadvantages of conventional devices,such as fast speed camera and conductivity ring *** results confirmed that the volume fraction of the solid phase in the transfer process was always less than 12%.To validate present experimental data,the existing empirical correlations together with the theoretical equations related to the multiphase flow was *** overall agreement between the theory and experimental solid delivery results was particularly good instead of the first stage of conveying *** drawback can be corrected by omitting the role of friction and shear stress at low air income *** was also found that the model developed by Kalenik failed to predict the performance of our airlift operation in terms of the mass flow rate of the coal particles.

关键词： Vertical velocity Non-spherical particle Submergence ratio Three-phase flow Churn flow Superficial velocity

A High-Order Discontinuous Galerkin Solver for Helically Symmetric Flows

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Communications in Computational Physics 2021年第6期30卷 288-320页

作者： Dominik Dierkes Florian Kummer Dominik Plumacher Department of Mechanical Engineering Technische Universitat DarmstadtOtto-Berndt-Straße 264287 DarmstadtGermany

We present a high-order discontinuous Galerkin(DG)scheme to solve the system of helically symmetric Navier-Stokes equations which are discussed in[28].In particular,we discretize the helically reduced Navier-Stokes equations emerging from a reduction of the independent variables such that the remaining variables are:t,r,ξwithξ=az+bϕ,where r,ϕ,z are common cylindrical coordinates and t the *** this,all three velocity components are kept non-zero.A new non-singular coordinateηis introduced which ensures that a mapping of helical solutions into the three-dimensional space is well *** that,periodicity conditions for the helical frame aswell as uniqueness conditions at the centerline axis r=0 are *** the sector near the axis of the computational domain a change of the polynomial basis is implemented such that all physical quantities are uniquely defined at the *** the temporal integration,we present a semi-explicit scheme of third order where the full spatial operator is splitted into a Stokes operator which is discretized implicitly and an operator for the nonlinear terms which is treated *** are conducted for a cylindrical shell,excluding the centerline axis,and for the full cylindrical domain,where the centerline is *** all cases we obtain the convergence rates of order O(hk+1)that are expected from DG *** addition to the first DG discretization of the system of helically invariant Navier-Stokes equations,the treatment of the central axis,the resulting reduction of the DG space,and the simultaneous use of a semi-explicit time stepper are of particular novelty.

关键词： Discontinuous Galerkin(DG) helical flows

Sustainable Urban Expansion:Lessons from Three Cases in Europe

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China City Planning Review 2021年第4期30卷 20-32页

作者： Paulina Schiappacasse Bernhard Muller Jiang Mengfan Faculty of Environmental Sciences Technische Universitat DresdenDresdenGermany

The article deals with sustainable urban expansion of cities in Europe and *** guiding question asks how planned urban expansion can promote urban sustainability and which perspectives this provides for future urban development in *** authors analyze three good practice examples in *** analytical framework includes five factors,i.e.,strategy,environment,diversity,connectivity,and *** a result,they derive six factors for successful sustainable urban expansion:①strategic planning guidance,②active participation and engagement,③quality-oriented master planning and design codes,④integrated and coordinated planning and implementation,⑤strong local government involvement,and⑥a strong drive towards *** correspond with recent trends in urban China and may help to make unavoidable urban growth more sustainable in the future.

关键词： urban sustainability integrated planning participation collaboration good practice

Application of the three-dimensional telegraph equation to cosmic-ray transport

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Research in Astronomy and Astrophysics 2016年第10期16卷 107-115页

作者： Robert C. Tautz Ian Lerche Zentrum fur Astronomie und Astrophysik Technische Universitat Berlin HardenbergstraBe 36 D-10623 Berlin Germany Institut fur Geowissenschaften Naturwissenschaftliche Fakultat Ⅲ Martin-Luther-Universitat Halle D-06099 HalleGermany

An analytical solution to the three-dimensional telegraph equation is presented. This equation has recently received some attention but so far the treatment has been one-dimensional. By using the structural similarity to the Klein-Gordon equation, the telegraph equation can be solved in closed form. Illustrative examples are used to discuss the qualitative differences from the diffusion solution. A comparison with a numerical test-particle simulation reveals that some features of an intensity profile can be better explained using the telegraph approach.

关键词： plasmas -- turbulence -- magnetic field -- diffusion -- solar wind

A modeling analysis of molecular orientation at interfaces by polarization-dependent sum frequency generation vibrational spectroscopy

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Chinese Journal of Catalysis 2019年第11期40卷 1655-1667页

作者： Xia Li Günther Rupprechter Institute of Materials Chemistry Technische Universitat Wien 1060 Vienna Austria

Sum frequency generation(SFG) vibrational spectroscopy has been proven an excellent tool to measure the molecular structures, symmetries and orientations at surfaces/interfaces because of its strong polarization dependence. However, a precise quantitative analysis of SFG spectral intensity and molecular orientation at interfaces must be carefully performed. In this work, we summarized the parameters and factors that are often ignored and illustrated them by evaluating studies of CO adsorption on the(111) facet of platinum(Pt) and palladium(Pd) single crystals at the gas(ultra-high vacuum, UHV)/solid interfaces and methanol(water) adsorption at the air/liquid(solid/liquid) interfaces in the presence of sodium iodide(chloride) salts. To intuitively estimate the influence of incidence angles and refractive indices on the SFG intensity, solely a defined factor of|Fyyz| was discussed, which can be individually separated from the macroscopic second-order non-linear susceptibility χ yyz^(2) term and represents the SSP intensity. Moreover, effects of refractive indices and the molecular hyperpolarizability ratio(R) were discussed in the orientational analysis of interfacial CO and methanol molecules. When IPPP/ISSP was identical, molecules with a larger R had smaller tilting angles(q) on Pt(assuming q < 51°), and CO molecules on Pd would tilt much closer to the surface than they did on Pt. A total internal reflection(TIR) geometry enhanced the SFG intensity, but it also amplified the influence of refractive index on SFG intensity at the solid(silica)/liquid interface. The refractive index and R-value had similar influence on the methanol orientation in the presence of sodium iodide salts at air/liquid and solid/liquid interfaces. This work should provide a guideline for analyzing the orientation of molecules with different R, which are adsorbed on catalysts or located at liquid interfaces involving changes of refractive indices.

关键词： Sum frequency generation spectroscopy Surface/interface Heterogeneous catalysis Molecular orientation Refractive index Incidence angles Molecular hyperpolarizability ratio

STRAIN-GRADIENT STRESS ANALYSIS IN SAINT-VENANT BENDING

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Acta Mechanica Sinica 1996年第3期12卷 225-242页

作者： Friedrich Wilhelm Hecker Jerzy Tadeusz Pindera technische universitat Braunschweig D-38106 Braunschweig Germany University of Waterloo Waterloo Ontario N2L 3G1 Canada

Light beam deflections caused by stress or strain gradients are inves- tigated analytically and experimentally in homogeneous beam specimens which are subjected to a particular case of flexure with shear. This study is a generalization of the prior an alytical-experimental examination of strain-gradient light deflections produced in stressed plates, which had concentrated on the simplest case where in- formation of interest is collected along a line of symmetry of the stress field. Main purpose of the present investigation is to document the efficacy of the strain-gradient method in analysis of the general case of stress state. The most interesting stress state is that in a beam subjected to the Saint-Venant bending, where the transversal and the longitudinal axes of the beam are in pure shear. The obtained results are compared with the predictions of the developed analytical models and with the pre- dictions of Filon's stress function. The procedures of evaluating the photoelastic and material coefficients using strain-gradient techniques were tested positively.

关键词： experimental stress analysis applied mechanics optical methods light propagation strain-gradient light bending testing mathematical models

Current Soil Nutrient Status of Intensively Managed Greenhouses

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Pedosphere 2012年第6期22卷 825-833页

作者： HU Yun-Cai SONG Zhi-Wen LU Wen-Long C. POSCHENRIEDER U. SCHMIDHALTER Chair of Plant Nutrition Technische Universitat Miinchen D-85350 Freising (Germany) Institute of Information Tianjin Academy of Agricultural Sciences Tianjin (China)

Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available N, P and K), acidification and salinization due to excessive input of fertilizers in greenhouses in Tianjin. The study showed that, in particular, soil available P content increased with the age of greenhouses. In contrast, our results did not reveal higher K accumulation and lowered pH in the greenhouse soils compared with cultivation in open fields. Over-fertilization, causing high NO 3 accumulation, most likely resulted in salinity problems in the greenhouses. Ninety percent of the investigated greenhouse soils had electrical conductivity values of saturated paste extracts of 2-10 d S m-1 , which might affect the yields of vegetable crops like green bean, pepper, cabbage, carrot, eggplant, lettuce, spinach, celery, cucumber and tomato. The findings of our survey of the current fertility and salinity problems in greenhouse soils suggest that there is an urgent need to improve the farmers' practices and strategies in fertilization management in greenhouses of China. Because education and the agricultural technical extension services may play a more important role in avoiding overuse of fertilizers, we suggest that current nutrient management practices should be improved in the near future through training of local farmers in farmers' schools and through strengthening the agricultural extension services with practical techniques.

关键词： electrical conductivity greenhouse vegetables over-fertilization soil pH soil survey