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Roughness Measurements with Polychromatic Speckles on Tilted Surfaces

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Nanomanufacturing and Metrology 2021年第4期4卷 237-246页

作者： Johannes Stempin andreas Tausendfreund Dirk Stobener andreas Fischer Bremen Institute for Metrology Automation and Quality ScienceUniversity of BremenLinzer Str.1328359 BremenGermany

Surface light scattering enables contactless and fast measurements of surface roughness.A surface inclination alters the direction of the scattering beam and thus the measured surface roughness is calculated from the detected intensity ***,an accurate sensor-surface alignment is *** order to achieve tilt-independent roughness measurements,a model-based evaluation approach for polychromatic speckle patterns is *** evaluating the shape of the superposed speckles,which occur for polychromatic illumination,with regard to the distance to the scattering centre,surfaces with an Sa roughness value in the range of 0.8-3.2μm are *** investigations demonstrate that the influence of a surface tilt up to±1.25°on the roughness measurement is reduced by 90%.As a result,the robustness of the polychromatic speckle roughness measurement is improved,which allows to speed up the adjustment of the measurement system or the surface sample,respectively.

关键词： Surface roughness Polychromatic light scattering Surface tilting In-process measurement

Evaluating performance of lignite pillars with 2D approximation techniques and 3D numerical analyses

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International Journal of Mining Science and Technology 2017年第6期27卷 929-936页

作者： Deliveris Alexandros V. Benardos andreas Centre for Research and Technology Hellas (CERTH) Chemical Process & Energy Resources Institute (CPERI) Athens GR15 125 Greece National Technical University of Athens (NTUA) School of Mining and Metallurgical Engineering (SMME) Athens GR15 780 Greece

This paper attempts to investigate the use of approximate 2D numerical simulation techniques for the evaluation of lignite pillar geomechanical response, formed via the room and pillar mining *** and applicability of the developing methodology are assessed through benchmarking with a more direct and accurate 3D numerical model. This analysis utilizes an underground lignite mine which is being developed in soft rock environment. Through the decisions made for the optimum room and pillar layout, the design process highlights the strong points and the weaknesses of 2D finite element analysis, and provides useful recommendations for future reference. The interpretations of results demonstrate that 2D approximation techniques come near quite well to the actual 3D ***, external load approximation technique seems to fit even better with the respective outcomes from the 3D analyses.

关键词： Geomechanics Room and pillar Underground lignite mine Finite element method 3D numerical analysis Average pillar stress

Odd-even effects in the structure and properties of aryl-substituted aliphatic self-assembled monolayers

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Nano Research 2024年第5期17卷 4231-4243页

作者： Piotr Cyganik andreas Terfort Michael Zharnikov Jagiellonian University Faculty of PhysicsAstronomy and Applied Computer ScienceSmoluchowski Institute of PhysicsŁojasiewicza 1130-348 KrakówPoland Institut für Anorganische und Analytische Chemie Universität FrankfurtMax-von-Laue-Straße 760438 FrankfurtGermany Applied Physical Chemistry Heidelberg UniversityIm Neuenheimer Feld 25369120 HeidelbergGermany

Self-assembled monolayers(SAMs)represent an important tool in context of nanofabrication and molecular engineering of surfaces and *** properties of functional SAMs depend not only on the character of the tail groups at the SAM-ambient interface,but are also largely defined by their *** its turn,the latter parameter results from a complex interplay of the structural forces and a variety of other factors,including so called odd-even effects,*** of the SAM structure and properties on the parity of the number(odd or even)of individual building blocks in the backbone of the SAM *** most impressive manifestation of the odd-even effects is the structure of aryl-substituted alkanethiolate SAMs on Au(111)and Ag(111),in which,in spite of the fact that the intermolecular interaction is mostly determined by the aryl part of the monolayers,one observes a pronounced dependence of molecular inclination and,consequently,the packing density of the SAM-forming molecules on the parity of number of methylene units in the alkyl *** we review the properties of the above systems as well as address fundamental reasons behind the odd-even effects,including the existence of a so-called bending potential,which is frequently disregarded in analysis of the structure-building *** generality of the odd-even effects in SAMs is additionally supported by the recent data for SAMs on GaAs,scanning tunneling microscopy data for SAMs on Ag(111),and the data for the monolayers with selenolate and carboxyl anchoring groups on Au(111)and Ag(111).The implications of these effects in terms of the control over the packing density and orientation of the tail groups at the SAM-ambient interface,structural perfection,polymorphism,temperature-driven phase transitions,and SAM stability toward such factors as ionizing radiation,exchange reaction,and electrochemical desorption are *** implications place the odd-even effects as an important tool

关键词： self-assembled monolayers molecular films surface and interface engineering odd-even-effects

Evolution and future of laparoscopic colorectal surgery

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World Journal of Gastroenterology 2014年第41期20卷 15119-15124页

作者： andreas M Kaiser Department of Colorectal Surgery Keck School of MedicineUniversity of Southern California

The advances of laparoscopic surgery since the early 1990 s have caused one of the largest technical revolutions in medicine since the detection of antibiotics(1922,Flemming),the discovery of DNA structure(1953,Watson and Crick),and solid organ transplantation(1954,Murray).Perseverance through a rocky start and increased familiarity with the chop-stick surgery in conjunction with technical refinements has resulted in a rapid expansion of the indications for minimally invasive ***-related factors initially contributed to this success and included the improved postoperative recovery and cosmesis,fewer wound complications,lower risk for incisional hernias and for subsequent adhesionrelated small bowel obstructions; the major breakthrough however came with favorable long-term outcomes data on oncological *** future will have to determine the specific role of various technical approaches,define prognostic factors of success and true progress,and consider directing further innovation while potentially limiting approaches that do not add to patient outcomes.

关键词： Laparoscopic Laparoscopy Open surgery Colorectal surgery Colectomy Robot

t-Private and t-Secure Auctions

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Journal of Computer Science & Technology 2008年第5期23卷 694-710页

作者： Markus Hinkelmann andreas Jakoby Peer Stechert Institut für Theoretische Informatik Universitt zu Lübeck Germany Fachgruppe Didaktik der Informatik und E-Learning Universitt Siegen Germany

In most of the auction systems the values of bids are known to the auctioneer. This allows him to manipulate the outcome of the auction. Hence, one might be interested in hiding these values. Some cryptographically secure protocols for electronic auctions have been presented in the last decade. Our work extends these protocols in several ways. On the basis of garbled circuits, i.e., encrypted circuits, we present protocols for sealed-bid auctions that fulfill the following requirements： 1） protocols are information-theoretically t-private for honest but curious parties; 2） the number of bits that can be learned by malicious adversaries is bounded by the output length of the auction; 3） the computational requirements for participating parties are very low： only random bit choices and bitwise computation of the XOR-function are necessary. Note that one can distinguish between the protocol that generates a garbled circuit for an auction and the protocol to evaluate the auction. In this paper we address both problems. We will present a t-private protocol for the construction of a garbled circuit that reaches the lower bound of 2t ＋ 1 parties, and Finally, we address the problem of bid changes in an auction. a more randomness efficient protocol for （t ＋ 1）^2 parties

关键词： multi-party private and secure computation garbled circuits private auctions

A Method for the Determination of Turbulence Intensity by Means of a Fast Response Pressure Probe and its Application in a LP Turbine

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Journal of Thermal Science 2012年第1期21卷 21-31页

作者： Davide Lengani Berardo Paradiso andreas Marn Inst. f. Thermal Turbomachinery and Machine Dynamics Graz University of Technology

This paper describes the measurements and the post-processing procedure adopted for the determination of the turbulence intensity in a low pressure turbine (LPT) by means of a single sensor fast response aerodynamic pressure probe. The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put into the adjustment of all relevant model parameters. Blade count ratio, airfoil aspect ratio, reduced massflow, reduced speed, inlet turbulence intensity and Reynolds numbers were chosen to reproduce the full scale LP turbine. Measurements were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The total pressure random fluctuations are obtained by selectively filtering, in the frequency domain, the deterministic unsteadiness due to the rotor blades and coherent structures. The turbulence intensity is derived from the inverse Fourier transform and the correlations between total pressure and velocity fluctuations. The determination of the turbulence intensity allows the discussion of the interaction processes between the stator and rotor for engine-representative operating conditions of the turbine.

关键词： Turbulence fast response aerodynamic pressure probe low pressure turbine.

Determination of particle exchange rates at over-flow weirs in horizontal fluidised beds by particle tracking velocimetry

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Particuology 2017年第3期15卷 1-9页

作者： Katja Meyer andreas Buck Evangelos Tsotsas Thermal Process Engineering Otto von Guericke University Magdeburg UniversitStsplatz 2 D-39106 Magdeburg Germany

Residence time distributions （RTDs） in horizontal fluidised beds have a huge effect on solid product properties and are infuenced by the internal design of the apparatus, e.g. the separation into different compartments by weirs. Weirs can be passed in or against the overall solid transport direction, with the back-flow resulting in axial dispersion, which is a measure of the spread of the RTD. Therefore, the ratio of exchange rates at weirs under different fluidisation conditions provides information on axial dispersion. In this work, a methodology based on particle tracking velocimetry is presented to obtain information on the exchange rates of particles at weirs in horizontal fluidised beds. The internal recirculation is studied for over-flow weirs with respect to different fluidisation conditions, providing a first step towards determining the effects of weirs and fluidisation conditions on axial dispersion and RTDs in horizontal fluidised beds.

关键词： Particle tracking velocimetry Horizontal fluidised bedAxial dispersion Granulation Drying

Deformation,fragmentation and acceleration of a controlled fragmentation charge casing

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Defence Technology（防务技术） 2019年第5期15卷 786-795页

作者： andreas Helte Olof Andersson Patrik Lundberg FOI Defence and SecuritySystems and Technology

Two different finite element software,LS-DYNA and Impetus,have been evaluated to test their ability to predict the deformation,fragmentation and acceleration of a controlled fragmentation charge *** general-purpose program LS-DYNA was used with a multi-material ALE formulation and a masspreserving erosion criterion coupled to a Johnson-Cook fracture *** the Impetus simulations,a third order Lagrangian element formulation was used for the casing and a node-splitting element erosion treatment coupled to a Cockcroft-Latham failure criterion was used to describe casing *** high-explosive gases were described by a discrete particle *** order to acquire data to validate our computational tools and constitutive models,a series of experiments have been performed using a laboratory charge with an internal grooved *** the test series,the charge geometry was fixed except that the groove depth were varied from very shallow to very deep resulting in different deformation patterns,fracture modes and terminal *** diagnostic tools captured the different stages of the expansion and fragmentation of the casing.A high-speed framing camera depicted the deformation pattern before fragmentation and was used to determine the moment when the casing *** different complementary techniques were used to follow the acceleration of the fragments;a Photon Doppler velocimetry to determine the initial acceleration of the casing,double exposed radiographs to estimate the fragment velocity after break-up and a high-speed video to determine the terminal velocity of the fragment after leaving the *** addition,the fragments were soft recovered in a set of sawdust pit tests and their final shape and weight were measured.A SEM was used to characterise the fracture surfaces and to determine the modus of fracture(tensile or shear failure).Comparisons to experiments show that both software can predict the change in deformation behaviour

关键词： Controlled fragmentation Fracture mechanics LS-DYNA Impetus

River Stabilisation by Breach-ramps and Widening

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四川大学学报（工程科学版） 2005年第S1期37卷 34-40页

作者： Markus AUFLEGER Tobias HAFNER andreas NIEDERMAYR Iint.of Hydraulic and Water Resources Eng. Technische Universitt MünvhenGermany

Numerous gravel-bed rivers are affected by unceasing degradation problems,mostly caused or in- creased by technical measures *** Germany removing the bank fixations is regarded as a concept to dissolve the *** allowing lateral erosion and in consequence river widening the bed load transport ca- pacity will be *** the eroded bank material will serve as additional sediment influx. Nevertheless in some cases additional measures are required for a sustainable stabilization o...

关键词： river widening breach-ramps