bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benchmarking pre‐trained Encoders for real‐time Semantic Road Scene Segmentation
Authors: Evers Lennart 
Published: January 2021

AbstractSemantic segmentation, i.e. assigning each pixel in an image a class to which it belongs, can be a part of the implementation for the perception model of autonomous vehicles. Over the last years multiple powerful neural network architectures for solving this task have been developed. In this work, a simple lightweight but modular, fully convolutional encoder‐decoder network has been implemented and multiple, publicly available pre‐trained classification networks are evaluated on their encoder performance on the Cityscapes [8] benchmark dataset with respect to their accuracy and their inference speed.
Finite element simulation of multi‐component vesicle morphologies undergoing phase separation
Authors: Savitha Eshwar J. , Mandadapu Kranthi K. , Sauer Roger A. 
Published: January 2021

AbstractMorphological changes in lipid bilayer vesicles are due to phase transitions and surface deformations occurring in unison. We present a dynamic chemo‐mechanical finite element model to study such changes. This is achieved by coupling two fourth order partial differential equations (PDEs): The Cahn‐Hilliard [2] mass balance equation based on irreversible thermodynamics, and the Kirchhoff‐Love [1] rotation free thin shell equation. The Helmholtz free energy consists of Helfrich energy to model elastic bending, and also includes in‐plane elastic energy with a finite shear modulus for the purpose of regularization. The geometry is discretized by C1‐continuous NURBS shape functions. An implicit second order accurate generalized‐α scheme is used for time integration. Newton‐Raphson iterations are utilized to solve the resulting linearized weak form monolithically. The proposed formulation is illustrated by a numerical example.
Particle Interactions in Magneto‐Active Elastomers: Experiments and Simulations
Authors: Metsch Philipp , Schmidt Henrik , Kalina Karl A. , Brummund Jörg , Auernhammer Günter K. , Kästner Markus 
Published: January 2021

AbstractIn this contribution, particle‐matrix interactions in magneto‐active elastomers are analyzed with regard to the resulting mechanical deformations. By comparing experimental observations with the results of finite element simulations, a fully coupled continuum model for magneto‐active elastomers is validated with the help of real data. The model under consideration permits the investigation of magneto‐active elastomers with arbitrary particle distances, shapes and volume fractions as well as magnetic and mechanical properties of the individual constituents. Our results show a very good agreement of experiments and numerical simulations ‐ the deformation behavior of the system under consideration is captured by the model qualitatively as well as quantitatively.
Development of a macroscale constitutive model for porous magneto‐ active polymers using a computational homogenization approach
Authors: Gebhart Philipp , Wallmersperger Thomas 
Published: January 2021

AbstractOver the last years there has been a growing interest in the study of the behavior of field‐responsive or so called smart materials. Porous magnetoactive polymers (MAPs) are a special class of these materials, where micron‐sized ferromagnetic particles are embedded into a porous crosslinked polymer matrix. Due to the mutual interaction of the particles upon magnetic stimulation, MAPs are able to deform and alter their effective material characteristics reversibly if subjected to a magnetic field. This strong magneto‐mechanical coupling makes them attractive for engineering applications e.g. in the field of sensors and actuators. The magneto‐mechanical behavior of porous MAPs is a complex phenomenon that spans over multiple length‐scales and essentially depends on (i) the constitutive behavior of the individual components, (ii) their morphology and microstructural arrangement and (iii) the macroscopic shape of the specimen. The strong shape effects pose a crucial challenge in the precise parameter identification of macroscopic models for MAPs based on experiments, see Keip & Rambausek [6] and Gebhart et al. [2, 3]. In order to circumvent these inherent problem, we propose a microscopic continuum‐based framework embedded into a suitable computational homogenization scheme to bridge between the micro‐ and macroscale, see Chatzigeorgiou et al. [1]. This modeling approach allows us to use much simpler constitutive models on the microscopic scale for which detailed and precise material parameters are available, see Kalina et al. [4, 5]. The proposed framework is then used to predict the effective macroscopic behavior of porous MAPs with random monodisperse microstructures. Based on the generated data set a thermodynamically consistent macroscale model for isotropic porous MAPs in an energy‐based constitutive setting is developed.
Data‐based models of drive technology for automation in automotive production
Authors: Dierkes Eva , Jung Francesca , Büskens Christof 
Published: January 2021

AbstractThe digital revolution, especially in the field of manufacturing, has great potential to change the economy sustainably. In this work, the development of methods for predictive maintenance and condition monitoring is a central focus. Data‐based models for drive technology in automotive production are investigated in order to generate adequate models, to make statements about the life cycle of the drives, or to suggest system modifications, such as the adjustment of weights. One task in this field is to detect anomalies or disturbances in given engine data. Since this collected data is variable and noisy, the detection of faults is non‐trivial. In this context two different methods for anomaly detection are studied. First, a model based on statistical analyses and second, a machine learning model is evaluated.
Real‐time parameter estimation for sensitivity‐based LQ regulator adaptation
Authors: Runge Margareta , Flaßkamp Kathrin , Büskens Christof 
Published: January 2021

AbstractIn this contribution we consider linear quadratic regulator problems subject to parameter perturbations within the system dynamics. Due to the perturbations, optimality of the regulator would be lost. Iteratively recomputing the optimal feedback matrix is likely to be too costly for real‐time applications, but approximated updates using parametric sensitivities can be efficiently derived. Online parameter identification is applied in order to obtain current parameter perturbations to which the controller shall be adapted. Numerical results for the benchmark example of the inverted pendulum on a cart are discussed.
Simulating 3D crack propagation with XFEM to investigate failure mechanism in high strength concrete
Authors: Patel Rohan , Scheiden Tim , Hüpgen Markus , Rozanski Corinna , Loehnert Stefan , Oneschkow Nadja 
Published: January 2021

AbstractHigh strength concrete compared to normal strength concrete has a denser micro‐structure, i.e. tight packaging or bonding between glued aggregates and cement paste, which increases strength and durability. The disproportionate ratio in ingredients of concrete, water to cement ratio and binding agents to form cement paste are subjected to self‐desiccation during the hydration process which leads to shrinkage, that has potential to form micro‐cracks and delamination within the ITZ (Interfacial Transition Zone), which ultimately causes deterioration in health of the structure. In order to investigate this phenomenon, a computational model to simulate the formation and propagation of cracks within the micro‐structure is developed. The geometrical model for the computation and simulation of the micro‐structure is extracted by means of computer tomography (CT) scans of concrete samples. The eXtended Finite Element Method (XFEM) in combination with level set techniques is employed to simulate discrete cracks and their advancement within the micro‐structure. The criterion for the crack propagation is obtained from a gradient enhanced damage model and once it is fulfilled, the crack geometry is updated using an advance algorithm for level sets.
In Silico Modeling of Coupled Physical‐Biogeochemical (P‐BGC) Processes in Antarctic Sea Ice
Authors: Thom Andrea , Ricken Tim 
Published: January 2021

AbstractAntarctic sea ice formation in the Marginal Ice Zone (MIZ) and its mutual effects on ocean biology and chemistry is very sensitive to climate change. The formation of ’pancake’ ice floes and the coupled physical‐biogeochemical (P‐BGC) processes can be modeled by using the continuum mechanical multi‐phase description of the extended Theory of Porous Media (eTPM), and simulated with the Finite Element Method (FEM). The ice formation is described via a salinity‐temperature equilibrium of the enclosed ocean water. The growth of the thriving ice algae, enclosed and attached to the pancake ice floes, is modeled with a phenomenological approach given with an ordinary differential equation.
Extension of the local strain approach to transient material behavior and residual stresses
Authors: Kühne David , Fiedler Melanie , Kästner Markus 
Published: January 2021

AbstractIn engineering practice generally empirical durability concepts, such as the Local Strain Approach (LSA) [1], are used for the fatigue life estimation of components. The LSA calculation is based on a given series of reversal points of the elastic stress history, e.g. computed in terms of a finite element model of the component. The fatigue life of components is subject to various factors. During the forming processes of steel‐alloy components, residual stresses are induced into components. In addition, steel‐alloys exhibit a cyclic transient material behavior, for example cyclic strain hardening with different characteristics under tensile and compressive loadings. While the state‐of‐the‐art LSA assumes stabilized cyclic material behaviour throughout the entire fatigue life of the component, this assumption is not adequate for residual stress‐afflicted components.
Coupled bending and torsional beam vibrations excited by a moving load
Authors: Holl Helmut J. , Keplinger Lukas 
Published: January 2021

AbstractFor a simply supported Bernoulli‐Euler beam under a moving load with constant velocity the bending and torsion vibrations are analysed. An analytical solution of the decoupled partial differential equations is derived based on the eigenmode expansion considering the boundary and initial conditions. For the pure bending and the pure torsion the analysis is performed and the beam vibrations are calculated. For various longitudinal speeds the results are plotted. The coupled bending and torsion deformations are computed using a modal transformation. The modal decoupling yields two separated ordinary differential equations in time which are computed using the derived closed form solutions. The solutions of the coupled equations are plotted and discussed. A comparison with a numerical calculation of a finite element model which shows good agreement.
Simulating vertebroplasty: A biomechanical challenge
Authors: Trivedi Zubin , Bleiler Christian , Gehweiler Dominic , Gueorguiev-Rüegg Boyko , Ricken Tim , Wagner Arndt , Röhrle Oliver 
Published: January 2021

AbstractEvery year, 1.4 million osteoporosis‐related vertebral fractures occur worldwide, which cause about 33 % of all osteoporotic fracture‐related deaths. Vertebroplasty is a medical procedure for treating vertebral fractures, wherein a polymer called bone‐cement is injected into the porous structure inside the vertebra. The associated risk of bone‐cement leaking outside of the vertebra can be mitigated by simulating the procedure, which can help clinicians to determine the right operating parameters in advance. However, modelling this procedure is challenging as well as computationally expensive using conventional methods, due to factors like the complex geometry of the trabecular bone structure, non‐Newtonian rheology of the fluids, curing of bone‐cement, and unknown patient‐specific material properties. In this work, some of these challenges are addressed by using a multiphasic continuum approach and adapting the constitutive models accordingly. The resulting developed model provides a computationally feasible framework for simulating the spread of bone‐cement in the whole vertebra.
Partitioned simulation of the acoustic behavior of flexible marine propellers using finite and boundary elements
Authors: Radtke Lars , Lampe Tobias , Abdel-Maksoud Moustafa , Düster Alexander 
Published: January 2021

AbstractIn the last years, classification societies have announced several specifications regarding the limitation of the noise level of ships. Accordingly, the prediction of the acoustic signature of cavitating propellers, which are the main source for noise generation, has attracted a lot of interest. For an accurate numerical simulation of the underlying physics, the deformation of the propeller has to be taken into account, which results in a fluid‐structure interaction (FSI) problem.In order to utilize different discretization methods for the individual sub‐problems, we apply a partitioned solution approach. This makes it possible to use a finite element solver for the structural problem, while a boundary element solver is used for the fluid problem. From the solution of the FSI problem, the acoustic pressure in the far field is obtained using the Ffowcs William‐Hawking equation.
Stochastic Modeling of a Lifted Methane/Air Jet Flame with Detailed Chemistry
Authors: Starick Tommy , Lignell David O. , Schmidt Heiko 
Published: January 2021

AbstractThis preliminary numerical study investigates a lifted methane/air jet flame in a vitiated coflow by means of the One‐Dimensional Turbulence (ODT) model. In the considered Cabra Burner configuration [Combust. Flame 143 491‐506 (2005)], a jet flame issues from a central nozzle into a vitiated coflow of hot combustion products from lean premixed hydrogen/air flames. ODT is a map‐based model for turbulent flow simulations which uses a stochastic formulation for the turbulent advection. The diffusion and reaction effects along the one‐dimensional domain are considered by temporally advancing deterministic evolution equations. ODT simulations are performed with a representation of the methane/air chemistry by a detailed 53‐species mechanism with 325 reactions. In this work, we present centerline profile of temperature and species concentrations obtained from ODT simulations using a cylindrical ODT‐formulation. Additionally, a two‐dimensional rendering of the temperature distribution is shown. Although the simulation of reactive jet configurations by means of ODT is not novel, the complex stabilization region depending on the flow conditions represents a challenge for the model. Considering the reduced order of the model, ODT is able to predict the flow characteristics and reasonably matches the existing experimental data.
Damping based on electromagnetic induction: A comparison of different minimal models
Authors: Rosenboom Mitja , Hetzler Hartmut 
Published: January 2021

AbstractDamping of structural vibrations is a crucial part of modern engineering. Using electromagnetic interactions for this purpose is a modern and promising approach. To gain better understanding of phenomena involved in this technique investigations on minimal models of a B‐field modulation dampers are shown. Therefore two different setups are compared. One uses a permanent magnet as the source for the magnetic field, one uses a coil, respectively an electro‐magnet as the source. The contribution focuses on differences that occur, due to the different designs. Therefore the static behavior is analyzed as well as the system response on a harmonic force excitation.
Identification of Optimal Shape and Material Parameters using Biparabolic Target Functions
Authors: Nostitz Niklas , Hendrik Kröger Nils , Ihlemann Jörn , Wulf Hans 
Published: January 2021

AbstractThe identification of optimal shapes and material parameters are reoccuring problems in engineering. While both tasks are often done in separate steps, previous works [4] had shown that a simultaneous identification is possible. Here, an identification was performed on a cylinder consisting of two materials which were separated by a NURBS layer curve. Different target values are investigated. In order to optimize these target values, a biparabolic approach is used.
A finite element formulation for a simplified, relaxed micromorphic continuum model
Authors: Chejanovsky Adam , Münch Ingo , Neff Patrizio 
Published: January 2021

AbstractWe discuss a simplified problem derived from the relaxed micromorphic continuum model in two dimensions. The model captures important aspects of the micromorphic approach even as a degeneration of the bulk model. Typically, the employed mechanical strain combines the gradient of displacements with the microdistortion field. The interaction between both fields is ruled by the minimization of the overall free energy, where we employ the Curl of the microdistortion. The Curl significantly influences the resulting equations for the balance of linear and angular momentum. Further, we explain the necessity of an extended finite element method. Finite elements based on solely the H1‐Hilbert space are not sufficient for the efficient approximation of the Curl based microdistortion. Therefore, we suggest using a hybrid scheme employing both, H1 and H(Curl) based functions. The resulting hybrid element formulation is successfully tested for a problem with a predefined Dirichlet boundary condition.
Ensemble reachability of homogenous parameter‐depedent systems
Authors: Schönlein Michael 
Published: January 2021

AbstractIn this paper we consider the class (θA, B) of parameter‐dependent linear systems given by matrices A ∈ ℂn×n and B ∈ ℂn×m. This class is of interest for several applications and the frequently met task for such systems is to steer the origin toward a given target family f(θ) by using an input that is independent from the parameter. This paper provides a collection of necessary and sufficient conditions for ensemble reachability for these systems.
A novel unknown input interval observer for systems not satisfying relative degree condition
Authors: Wang Xianghua , Tan Chee Pin , Liu Lanjun , Qi Qingyuan 
Published: January 2021

AbstractIn this article, a novel unknown input interval observer (UIIO) is proposed for systems not satisfying the relative degree condition. In interval estimation, estimation errors are required not only positive but also convergent. For this purpose, some works combined unknown input observer with interval estimation, namely UIIO where by virtue of some transformations, some states are expressed as functions of outputs and other states which are decoupled from the unknown input. Nevertheless, complete decoupling can be guaranteed when the systems satisfy relative degree condition, which does not hold for some practical systems. Although some works have been done to relax the requirement on relative degree condition, they usually construct auxiliary outputs using high‐order differentiators which necessitates that the signals are smooth enough as well as that their derivatives are bounded, limiting the application of existing approaches and also increasing the computational cost. Motivated by the discussions above, a novel UIIO scheme combining the interval observation technique with adaptive sliding mode is proposed, without the relative degree condition and free from differentiating signals, hence the design process is simplified and the computational cost is decreased. Finally, simulations are conducted to verify the effectiveness of the proposed scheme.
Insights into the Recent Synthetic Advances of Organoselenium Compounds
Authors: Makhal Priyanka N. , Nandi Arijit , Kaki Venkata Rao 
Published: January 2021

AbstractThe ever‐growing interest for organoselenium compounds amongst the chemists has made commendable impact in the field of medicinal chemistry, material chemistry, chemical biology and biochemistry. Researchers have progressively contributed in the development of organoselenium compounds over the years which has been periodically reviewed. On the similar note, this review attempts at providing an overview of the recent advances made in organoselenium chemistry while covering their catalytic indulgence in different transformational approaches, their role in asymmetric synthesis, and synthetic approaches steering their synthesis. These approaches encompass selenofunctionalization and/or cyclization, electrochemical selenylation, bromolactonization, [2,3]‐ or [1,2]‐sigmatropic rearrangement reactions among others. Herein, we have focused on the synthetic approaches developed for the past three years that have not been covered in previously reviewed scientific material. With the knowledge of the recent progress covered, this review could contribute towards future development of organoselenium compounds along with the improvement of the current status.
Nanomedicines for Endometriosis: Lessons Learned from Cancer Research
Authors: Moses Abraham S. , Demessie Ananiya A. , Taratula Olena , Korzun Tetiana , Slayden Ov D. , Taratula Oleh 
Published: January 2021

AbstractEndometriosis is an incurable gynecological disease characterized by the abnormal growth of endometrium‐like tissue, characteristic of the uterine lining, outside of the uterine cavity. Millions of people with endometriosis suffer from pelvic pain and infertility. This review aims to discuss whether nanomedicines that are promising therapeutic approaches for various diseases have the potential to create a paradigm shift in endometriosis management. For the first time, the available reports and achievements in the field of endometriosis nanomedicine are critically evaluated, and a summary of how nanoparticle‐based systems can improve endometriosis treatment and diagnosis is provided. Parallels between cancer and endometriosis are also drawn to understand whether some fundamental principles of the well‐established cancer nanomedicine field can be adopted for the development of novel nanoparticle‐based strategies for endometriosis. This review provides the state of the art of endometriosis nanomedicine and perspective for researchers aiming to realize and exploit the full potential of nanoparticles for treatment and imaging of the disorder.
Nanoscopic Structural Fluctuations of Disassembling Microtubules Revealed by Label‐Free Super‐Resolution Microscopy
Authors: Vala Milan , Bujak Łukasz , García Marín Antonio , Holanová Kristýna , Henrichs Verena , Braun Marcus , Lánský Zdeněk , Piliarik Marek 
Published: January 2021

AbstractMicrotubules are cytoskeletal polymers of tubulin dimers assembled into protofilaments that constitute nanotubes undergoing periods of assembly and disassembly. Static electron micrographs suggest a structural transition of straight protofilaments into curved ones occurring at the tips of disassembling microtubules. However, these structural transitions have never been observed and the process of microtubule disassembly thus remains unclear. Here, label‐free optical microscopy capable of selective imaging of the transient structural changes of protofilaments at the tip of a disassembling microtubule is introduced. Upon induced disassembly, the transition of ordered protofilaments into a disordered conformation is resolved at the tip of the microtubule. Imaging the unbinding of individual tubulin oligomers from the microtubule tip reveals transient pauses and relapses in the disassembly, concurrent with increased organization of protofilament segments at the microtubule tip. These findings show that microtubule disassembly is a discrete process and suggest a stochastic mechanism of switching from the disassembly to the assembly phase.