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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

SDL Enhancements and Integration into the Design-Lifecycle of Telecommunication Services

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SDL Enhancements and Integration into the Design-Lifecycle o...

Evolution and future of laparoscopic colorectal surgery

1998 International Conference on Communication Technology

作者： Marc Born andreas Hoffmann Mario winkler Nils Fischbeck GMD FOKUS Kaiserin-Augusta-Allee 31 D-10589 BerlinGermany Humboldt University of Berlin Axel-Springer-Strasse 54 a D-10117 BerlinGermany

＜正＞The complexity of telecommunication services has become increasingly high in recent *** to this complexity and the distributed nature of the services on the one hand and the requirement to come up with a short time to market on the other hand,new methods,techniques and tools covering the whole service development lifecycle are needed. This paper proposes to use ODL in connection with SDL to gain computational specifications which expose detailed behavior *** advantages of using ODL with SDL are shown with an *** this case study parts of the TINA retailer reference point is specified. The paper introduces a new mapping from the ODP computational concepts to SDL which is based on SDL extensions currently in the standardization *** new features are exception handling,remote procedure reject and associated timer.

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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

Accurate large-scale simulations of siliceous zeolites by neural network potentials

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npj Computational Materials 2022年第1期8卷 1662-1673页

作者： andreas Erlebach Petr Nachtigall LukášGrajciar Department of Physical and Macromolecular Chemistry Charles UniversityHlavova 812800Prague 2Czech Republic

The computational discovery and design of zeolites is a crucial part of the chemical *** highly accurate while computational feasible protocol for identification of hypothetical siliceous frameworks that could be targeted experimentally is a great *** tackle this challenge,we trained neural network potentials(NNP)with the SchNet architecture on a structurally diverse database of density functional theory(DFT)*** database was iteratively extended by active learning to cover not only low-energy equilibrium configurations but also high-energy transition *** demonstrate that the resulting reactive NNPs retain DFT accuracy for thermodynamic stabilities,vibrational properties,as well as reactive and non-reactive phase *** a showcase,we screened an existing zeolite database and revealed>20k additional hypothetical frameworks in the thermodynamically accessible range of zeolite ***,our NNPs are expected to be essential for future high-throughput studies on the structure and reactivity of siliceous zeolites.

关键词： synthesis zeolite zeolites

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

Tribology of self-lubricating high performance ATSP,PI,and PEEK-based polymer composites up to 300℃

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Friction 2023年第1期11卷 141-153页

作者： Kian BASHANDEH Pixiang LAN andreas A.POLYCARPOU Department of Mechanical Engineering Texas A&M UniversityCollege StationTexas 77843USA ATSP Innovations Inc.Texas 77055USA

High-performance polymers(HPPs)are increasingly used in different industrial machinery components,particularly for rubbing parts that demand reliable and durable operation at extreme sliding conditions such as elevated temperature environments,where the use of conventional lubricants is not *** current study investigates the role of environmental temperature on the tribological properties of three advanced HPPs,namely aromatic thermosetting copolyester(ATSP),polyimide(PI),and polyether ether ketone(PEEK)based polymer *** experiments were carried out at different environmental temperatures from room temperature up to 300℃,and under dry sliding *** attention was given to the role of temperature on the development of transfer films and its subsequent effect on the tribological *** ATSP composite was recommended as the best performing material,based on the overall tribological performance at all examined operating temperatures.

关键词： aromatic thermosetting copolyester(ATSP) polyimide(PI) polyether ether ketone(PEEK) high temperature tribology transfer film