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Numerical simulation of flooding induced uplift for abandoned coal mines:simulation schemes and parameter sensitivity

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International Journal of Coal Science & Technology 2021年第6期8卷 1238-1249页

作者： Jian Zhao Heinz Konietzky Martin Herbst Roy Morgenstern Geotechnical Institute TU Bergakademie FreibergGustav-Zeuner-Straβe 109599 FreibergGermany

Numerical simulation approaches have been widely applied to study mining induced subsidence,and they are potential methods to study the flooding induced uplift for abandoned *** paper gives an overview about different numerical approaches to simulate uplift induced by flooding abandoned underground mines,including three different hydraulic conditions,considering both unconfined and confined water *** basic simulation schemes using 1-dimensional rock column models verified by analytical solutions demonstrate these *** results reveal that flooding induced uplift is mainly related to the pore pressure in the mine *** parameter study documents that height and stiffness of the mine goaf have the strongest influence on maximum surface uplift.

关键词： Surface uplift Abandoned mine flooding Numerical simulation Analytical solution Parameter sensitivity

Redundancy in Biology and Robotics:Potential of Kinematic Redundancy and its Interplay with elasticity

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Journal of Bionic engineering 2020年第4期17卷 695-707页

作者： Tom Verstraten Christian Schumacher Rapha(e)l Furnémont Andre Seyfarth Philipp Beckerle Robotics and Multibody Mechanics Research Group(R&MM) Vrije Universiteit Brussel and Flanders MakePleinlaan 21050 ElseneBelgium Institute of Sports Science TU DarmstadtMagdalenenstraβe 2764289 DarmstadtGermany elastic Lightweight Robotics Group Robotics Research InstituteTU DortmundOtto-Hahn-Straβe 844227 DortmundGermany Institüt fur Mechatronische Systeme im Maschinenbau TU DarmstadtOtto-Berndt-Straβe 264287 DarmstadtGermany

Redundancy facilitates some of the most remarkable capabilities of humans,and is therefore omni-present in our *** relationship between redundancy in robotics and biology is investigated in detail on the Series elastic Dual-Motor Actuator(SeDMA),an actuator inspired by the kinematic redundancy exhibited by *** actuator consists of two motors coupled to a single spring at the *** a system has a redundant degree of freedom,which can be exploited to optimize aspects such as accuracy,impedance,fault-tolerance and energy *** test its potential for human-like motions,the SeDMA actuator is implemented in a hopping *** on a physical demonstrator show that the robot's movement patterns resemble human squat *** conclude that robots with bio-inspired actuator designs facilitate human-like movement,although current technical limitations may prevent them from reaching the same dynamic and energetic performance.

关键词： bioinspired redundant actuation series elastic actuation hopping robots energy efficiency human physiology

A Practical Approach to Representation of Real-time Building Control Applications in Simulation

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International Journal of Automation and computing 2020年第3期17卷 464-478页

作者： Azzedine Yahiaoui Center for Building&Systems Eindhoven University of Technology(TU/e)PO Box 513Eindhoven 5600MBNetherlands

Computer based automation and control systems are becoming increasingly important in smart sustainable buildings,often referred to as automated buildings(ABs),in order to automatically control,optimize and supervise a wide range of building performance applications over a network while minimizing energy consumption and associated green house gas *** technology generally refers to building automation and control systems(BACS)*** of costly and time-consuming experiments,this paper focuses on development and design of a distributed dynamic simulation environment with the capability to represent BACS architecture in simulation by run-time coupling two or more different software tools over a *** involves using distributed dynamic simulations as means to analyze the performance and enhance networked real-time control systems in ABs and improve the functions of real BACS *** application and capability of this new dynamic simulation environment are demonstrated by an experimental design,in this paper.

关键词： Distributed dynamic simulation networked control systems building performance applications smart buildings building automation and control systems(BACS)architecture

Seamless and non-repetitive 4D texture variation synthesis and real-time rendering for measured optical material behavior

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Computational Visual Media 2019年第2期5卷 161-170页

作者： Martin Ritz Simon Breitfelder Pedro Santos Arjan Kuijper Dieter W. Fellner Fraunhofer IGD Darmstadt64283Germany tu Darmstadt Darmstadt64289Germany tu Graz Graz8010Austria

We show how to overcome the single weakness of an existing fully automatic system for acquisition of spatially varying optical material behavior of real object surfaces. While the expression of spatially varying material behavior with spherical dependence on incoming light as a 4D texture(an ABTF material model) allows flexible mapping onto arbitrary 3D geometry, with photo-realistic rendering and interaction in real time,this very method of texture-like representation exposes it to common problems of texturing, striking in two disadvantages. Firstly, non-seamless textures create visible artifacts at boundaries. Secondly, even a perfectly seamless texture causes repetition artifacts due to their organised placement in large numbers over a 3D surface. We have solved both problems through our novel texture synthesis method that generates a set of seamless texture variations randomly distributed over the surface at shading time. When compared to regular 2D textures, the inter-dimensional coherence of the 4D ABTF material model poses entirely new challenges to texture synthesis, which includes maintaining the consistency of material behavior throughout the 4D space spanned by the spatial image domain and the angular illumination hemisphere. In addition, we tackle the increased memory consumption caused by the numerous variations through a fitting scheme specifically designed to reconstruct the most prominent effects captured in the material model.

关键词： optical material behavior reflectance modeling 4D texture synthesis texturing

Hybrid Additive Manufacturing of Forming Tools

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Automotive Innovation 2023年第3期6卷 311-323页

作者： Hamed Dardaei Joghan Ramona Holker‑Jager Anna Komodromos A.erman Tekkaya Institute of Forming Technology and Lightweight Components(IUL) TU Dortmund UniversityBaroper Stra.e 30344227 DortmundGermany

Additive manufacturing(AM)is widely used in the automotive industry and has been expanded to include aerospace,marine,and *** flexibility and the possibility of manufacturing complex parts in AM motivate the integration of additive manu-facturing with classical forming technologies,which can improve tooling concepts and reduce *** study presents three applications of this ***,the possibility of successful utilization of selective laser melting for manufacturing extrusion tools with complex cooling channels and paths for thermocouples is reported,leading to significantly reduced inner die temperatures during the extrusion ***,sheet lamination is integrated with laser metal deposition(LMD)to manufacture deep-drawing *** results are achieved in reducing the stair step effect,which is the main challenge in sheet lamination,by LMD and following post-processing such as milling,ball burnishing,and laser *** new manufacturing route shows that LMD can economically and efficiently reduce the stair step effect and omit the hardening step from the conventional manufacturing process ***,LMD is used to manufacture a hot stamping punch with improved surface roughness by ball burnishing and near-surface complex cooling *** experimental results show that the manufactured punch has lower temperatures during hot stamping compared with the conventionally manufactured *** study shows the successful integration of AM processes with classical forming processes.

关键词： Additive manufacturing Laser metal deposition Selective laser melting Rapid tooling Forming tool Layer laminated manufacturing

Simulating small-scale climate change effects-lessons from a short-term field manipulation experiment on grassland arthropods

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Insect Science 2013年第5期20卷 662-670页

作者： Sascha Buchholz Dorothee Rolfsmeyer Jens Schirmel Department of ecology TU Berlin Institute of Landscape ecology University of Munster Robert-Koch-Straβe 26 48149 Munster ecosystem Analysis University ofKoblenz-Landau Fortstraβe 7 76829 Landau Germany

Climate change is expected to cause major consequences on biodiversity. Understanding species-specific reactions, such as species shifts, species declines, and changes in population dynamics is a key issue to quantify large-scale impacts of climate change on biotic communities. As it is often impossible or at least impracticable to conduct large-scale experiments on biotic responses to climate change, studies at a smaller scale may be a useful alternative. In our study, we therefore tested responses of grassland arthropods （carabid beetles, spiders, grasshoppers） to simulated climate change in terms of species activity densities and diversity. We conducted a controlled field experiment by changing water and microclimatic conditions at a small scale （16 m2）. Roof constructions were used to increase drought-like conditions, whereas water supply was enhanced by irrigation. In all, 2 038 carabid beetles （36 species）, 4 893 spiders （65 species）, and 303 Orthoptera （4 species） were caught using pitfall traps from May to August, 2010. During our experiment, we created an artificial small-scale climate change; and statistics revealed that these changes had short-term effects on the total number of individuals and Simpson diversity of the studied arthropod groups. Moreover, our results showed that certain species might react very quickly to climate change in terms of activity densities, which in turn might influence diversity due to shifts in abundance patterns. Finally, we devised methodological improvements that may further enhance the validity of future studies.

关键词： carabid beetles drought global wanning grasshoppers irrigation spiders

Development of a classification system based on corneal biomechanical properties using artificial intelligence predicting keratoconus severity

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eye and Vision 2021年第3期8卷 203-213页

作者： Robert Herber Lutz e.Pillunat Frederik Raiskup Department of Ophthalmology University Hospital Carl Gustav CarusUniversitätsklinikum Carl Gustav Carus an der Technischen Universität DresdenFetscherstraße 74TU 01307 DresdenGermany

Background:To investigate machine-learning(ML)algorithms to differentiate corneal biomechanical properties between different topographical stages of keratoconus(KC)by dynamic Scheimpflug tonometry(CST,Corvis ST,Oculus,Wetzlar,Germany).In the following,ML models were used to predict the severity in a training and validation ***:Three hundred and eighteen keratoconic and one hundred sixteen healthy eyes were included in this monocentric and cross-sectional pilot *** corneal response(DCR)and corneal thickness related(pachymetric)parameters from CST were chosen by appropriated selection techniques to develop a ML *** stage of KC was determined by the topographical keratoconus classification system(TKC,Pentacam,Oculus).Patients who were classified as TKC 1,TKC 2 and TKC 3 were assigned to subgroup mild,moderate,and advanced *** patients were classified as TKC 1-2,TKC 2-3 or TKC 3-4,they were assigned to subgroups according to the normative range of further corneal indices(index of surface variance,keratoconus index and minimum radius).Patients classified as TKC 4 were not included in this study due to the limited amount of *** discriminant analysis(LDA)and random forest(RF)algorithms were used to develop the classification *** were divided into training(70%of cases)and validation(30%of cases)***:LDA model predicted healthy,mild,moderate,and advanced KC eyes with a sensitivity(S_(n))/specificity(S_(p))of 82%/97%,73%/81%,62%/83%and 68%/95%from a validation dataset,*** the RF model,a S_(n)/S_(p) of 91%/94%,80%/90%,63%/87%,72%/95%could be reached for predicting healthy,mild,moderate,and advanced KC eyes,*** overall accuracy of LDA and RF was 71%and 78%,*** accuracy for KC detection including all subgroups of KC severity was 93%in both ***:The RF model showed good accuracy in predicting healthy eyes and various stages of *** accuracy was superior with respec

关键词： Artificial intelligence Corneal biomechanics Corvis ST Grading Keratoconus Machine learning

An efficient Calculation of Photonic Crystal Band Structures Using Taylor expansions

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Communications in Computational Physics 2014年第10期16卷 1355-1388页

作者： Dirk Klindworth Kersten Schmidt Research Center MATHeON TU BerlinDepartment of MathematicsStraße des 17.Juni 13610623 BerlinGermany.

In this paper we present an efficient algorithm for the calculation of photonic crystal band structures and band structures of photonic crystal *** method relies on the fact that the dispersion curves of the band structure are smooth functions of the quasi-momentum in the one-dimensional Brillouin *** show the derivation and computation of the group velocity,the group velocity dispersion,and any higher derivative of the dispersion *** derivatives are then employed in a Taylor expansion of the dispersion *** control the error of the Taylor expansion with the help of a residual estimate and introduce an adaptive scheme for the selection of nodes in the one-dimensional Brillouin zone at which we solve the underlying eigenvalue problem and compute the derivatives of the dispersion *** proposed algorithm is not only advantageous as it decreases the computational effort to compute the band structure but also because it allows for the identification of crossings and anti-crossings of dispersion curves,*** identification is not possible with the standard approach of solving the underlying eigenvalue problem at a discrete set of values of the quasi-momentum without taking the mode parity into account.

关键词： Photonic crystals band structure calculation group velocity Taylor expansion adaptivity

experimental investigation of stress unloading effects on rock damage and confining pressure-dependent crack initiation stress of porous sandstone under true triaxial stress environments

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Rock Mechanics Bulletin

Rock Mechanics Bulletin 2024年第2期3卷 78-86页

作者： Qingsheng Bai Max Friedel Heinz Konietzky Geotechnical Institute TU Bergakademie FreibergGustav-Zeuner-Straße 109599 FreibergGermany

This study investigates the impact of intermediate(σ_(2))and minimum(σ_(3))principal stress unloading on damage behavior and the confining pressure influence on crack initiation stress(σci)in true triaxial stress conditions,utilizing large-scale cubic *** distinct true triaxial tests were executed,examining the effects of confining stress(σ_(2)andσ_(3))unloading on porous sandstone damage and the correlation between confining stress andσ*** emission(Ae)parameters,signal characteristics,and wave velocity variations were utilized to elucidate cracking mechanisms and damage development in the *** tests reveal consistent ve-locities in three orthogonal directions(V_(11),V_(22),and V_(33))during the initial two unloading *** the subse-quent three stages,confining stress unloading leads to a decrease in wave velocity in the corresponding direction,while velocities in the other two directions remain nearly ***,σ_(2)unloading generates higher amplitude Ae signals compared toσ_(3)unloading,with over 70%of the micro-cracks categorized as *** the incremental loading tests,σ_(ci) is found to be contingent on confining pressure,withσ_(2)playing a crucial ***σ_(1) loading,V_(33) decreases,indicating additional crack formation;conversely,σ_(3)loading results in V33 increase,signifying the continuous closure of existing *** of the experiments are summarized and prospects in this domain are outlined.

关键词： Stress unloading Damage behavior True triaxial stress environments Wave velocity Crack initiation stress