bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical investigation of hot bulk forming processes with respect to the resulting residual stress distribution
Authors: Hellebrand Sonja , Brands Dominik , Scheunemann Lisa , Schröder Jörg
Published: March 2023

The cost‐ and time‐efficient design of today's manufacturing processes is closely linked to numerical simulations. By developing and applying suitable simulation models, component properties can be specifically predicted and, if necessary, modified according to the customer's specifications. One important aspect of this is the adjustment towards advantageous residual stress profiles, for example to increase service life or wear resistance. Hot forming processes offer the advantage of the interaction of thermal, mechanical and metallurgical effects. In particular, cooling after prior heating and forming, in this case upsetting, results in a phase transformation on the microscale in the material. The residual stress state, which arises from dislocations in the atomic lattice, will be considered in more detail in this contribution.Here, the focus lies on the analysis of microscopic characteristics utilizing a multi‐scale Finite Element model in terms of a FE2 approach.
Sensitivity of predicted stresses in thick‐walled steel/ceramics spherical FGM‐structures to parameter uncertainties
Authors: Arslan Eray , Mack Werner
Published: March 2023

The effects of both material data uncertainties of the constituents and of volume fraction deviations from the design values caused by the manufacturing process on the forecasted stresses in a spherical container of functionally graded material (FGM) are investigated. Specifically, a steel/alumina hollow sphere subject to internal pressure and homogeneous heating is studied. It is shown that even moderate uncertainties and deviations may cause large expectation ranges of von Mises equivalent stresses, and this issue may yet predominate over the question for the most reasonable homogenization scheme(s).
Bonded particle models for discrete element simulation of porous granules
Authors: Rotter Sonja , Woitzik Christian , Düster Alexander
Published: March 2023

The growing interest in granular materials used in mechanical applications, for example as crash absorbers in ship collisions, leads to an increased need for numerical models to simulate such granules. Since, in the case of an application as a crash absorber, the fracture behaviour of the granules is of particular interest, the numerical models must be able to simulate the breakage and predict, for example, the energy dissipation during fracture. For this purpose, a discrete element method is used together with a bonded particle model. Since the bond model mainly affects the fracture of particles, this work focuses on new models and their influence on the breaking behaviour of granules.
Efficient simulation of cables with anisotropic high‐order solid finite elements
Authors: Hildebrandt André , Sharma Prateek , Diebels Stefan , Düster Alexander
Published: March 2023

Cables are slender structures with a complex geometry, that can undergo large deformations during their installation or in dynamic environments. In combination with their complex inner structure they pose a challenging problem for finite element simulations. In this article a simplified approach is presented to model cables by using an effective material and a homogeneous cross‐section, which is anisotropic in the elastic and inelastic domain. For the high‐order hierarchic shape functions with quasi‐regional mapping, anisotropic ansatz spaces are applied in tension, torsion and bending simulations. The identification of material parameters is conducted based on experimental results for a tension and a torsion test using the particle swarm optimization algorithm. Finally, the identified parameters are validated for a combined load case with torsion and free bending, showing a promising approach regarding the simulation of cable structures.
Sparse signals on hypergraphs
Authors: Emmrich Tarek , Juhnke-Kubitzke Martina , Kunis Stefan
Published: March 2023

Signals with a sparse representation in a given basis as well as Laplacian eigenvectors of graphs play a big role in signal processing and machine learning. We put these topics together and look at signals on graphs that have a sparse representation in the basis of eigenvectors of the Laplacian matrix, which may appear after convolution with an unknown sparse filter. We give explicit algorithms to recover those sums by sampling the signal only on few vertices, i.e., the number of required samples is independent of the total size of the graph and takes only local properties of the graph into account. We generalize these methods to simplicial complexes.
Influence of a transient bubble dynamics cavitation model for squeeze film dampers on the run‐up behaviour of a turbocharger rotor
Authors: Drapatow Thomas , Woschke Elmar
Published: March 2023

The force response of squeeze film dampers and hydrodynamic bearings is significantly influenced by the occurence of cavitation inside the lubricant films. The viscosity of the occuring mixture of oil and air bubbles is vastly different than that of pure lubricant and therefore changes the pressure build‐up and thereby the stiffness and damping properties of the lubrication films. To accurately predict the force response of a squeeze film damper, the cavitation and its effect on the pressure build‐up therefore has to be taken into account. Well known cavitation algorithms for lubrication problems, like the Elrod algorithm or the two‐phase‐model, neglect the transient nature of outgassing and assume instantaneous bubble formation and collapse. In the presented paper, a transient bubble dynamics model based on the Rayleigh‐Plesset‐Scriven equation is utilised instead and its effect on the rotordynamic behaviour of a turbocharger rotor is examined based on fully transient multi body dynamics simulations.
Modeling of Growth using an Immersed Finite Element Method
Authors: Ebrahem Adnan , Hiemstra René R. , Stoter Stein K. F. , Schillinger Dominik
Published: March 2023

To prevent remeshing, we explore the use of a non‐boundary‐fitted finite element method for the computational modeling of growth including contact mechanics. Accordingly, we utilize a mesh‐related mapping procedure for the use of implicit geometry description by a level set function within the framework of immersed methods. Hence, our framework provides a setting to include patient‐specific geometries based on imaging data as we use a level set function for the implicit geometry description. In this contribution, we show that the proposed approach is a viable alternative for problems with mesh‐related obstacles, in particular when large growth simulations on complex patient‐specific geometries are of primary interest.
Numerical simulation of fluid flow with a fast Boundary‐Domain Integral Method
Authors: Tibaut Jan , Ravnik Jure , Schanz Martin
Published: March 2023

For the simulation of fluid flow the velocity‐vorticity formulation of the Navier‐Stokes equations can be used. Approximating the first order time derivative in these equations by finite differences, essentially, the Yukawa equation for the velocity has to be solved with an inhomogeneity governed by the vorticity. Applying the Boundary Element Method to such problems is not straightforward. However, the Boundary‐Domain Integral Method (BDIM) can be used, which requires to solve beside the boundary integrals as well a domain integral due to the inhomogeneity. Classical BEM formulations have a quadratic complexity with respect to the unknowns on the boundary and, for the BDIM additionally, for the unknowns in the domain. This prevents the BDIM from being applied to real‐world problems.

To reduce the quadratic complexity in BEM, approximation methods like the fast multipole method, ℋ‐matrices in combination with the adaptive cross approximation or the ℋ2 ‐matrix technique can be used. All these methods reduce the complexity to an almost linear order. Here, the ℋ2 ‐matrix technique is applied to reduce storage and computing time for the right hand side, i.e., for the matrix of the domain integrals. Based on interpolatory kernel expansions and an heuristic criterium for too small matrix entries an almost linear complexity can be achieved. The numerical studies focus on a lid‐driven cavity. The complexity reduction is demonstrated.
MHD flow of submerged jets behind the inlet disturbance
Authors: Krasnov Dmitry , Listratov Yaroslav , Belyaev Ivan , Kolesnikov Yuri , Sviridov Evgeny , Zikanov Oleg
Published: March 2023

In a broad variety of configurations in technology and industrial applications, the properties of liquid metal flows subjected to strong magnetic fields, are largely governed by the dynamics of coherent structures, known to settle several basic types, such as thin shear layers, forming near the walls or within the fluid domain, vortices extended along the field, or planar and round jets. In some cases, these structures are created by the design, like a submerged jet formed by a sudden expansion from the nozzle into a blanket channel, or jets formed behind some flow obstruction. In the other cases this may be due to instability and evolution of secondary structures, for example, descending and ascending jets appearing as a result of convective instability in blanket channels. In this study, we undertake an attempt to affect liquid metal flow via inlet disturbance formed by a simple rod placed along the magnetic induction lines. The disturbance can generate flat jets behind the rod and, furthermore, a sustainable flow of anisotropic vortical perturbations further downstream the flow. We seek to analyze the most important mechanisms of the flow dynamics and effects of magnetic field on the integral system properties of enhancing mixing, mass and heat transport for such flow. The most optimal regimes of vortex generation are found to be governed by the magnetic interaction parameter (Stuart number). The exact ratio of the optimal Stuart number is found to be in a range between 20 and 40, based on the channel double width as a characteristic size. The observed vortices attain quasi‐2D shape and exist at a length of dozens of duct calibers, being the strongest at higher flow rates. The obtained flow regimes and their turbulent properties are also found to resemble significant similarity to the results on quasi‐2D turbulence found in prior studies of channel and duct flows under spanwise magnetic field.
Thermo‐chemo‐mechanical modelling of a curing process combined with mean‐field homogenization methods at large strains
Authors: Lenz Peter , Mahnken Rolf
Published: March 2023

Nowadays, polymeric materials have several applications, where carbon and glass fibre‐reinforced composite materials, epoxy laminates and (nano‐)particle‐reinforced polymer structures are typical examples. Starting with an initial uncured state of the matrix, a mixture of resin and curing agent undergoes a polymerization process which cures the matrix to a solid material. The curing process is highly temperature dependent and influences the mechanical, thermal and chemical properties of a composite strongly. There are different options to treat such an inhomogeneous material. One option are the semi‐analytical mean‐field homogenization methods. Mean‐field homogenization methods are originally developed for linear elastic materials. To account for non‐linear materials a special treatment is needed. A mean‐field homogenization framework is derived for constitutive multiscale (micro‐meso‐macro) modelling of a coupled thermo‐chemo‐mechanical problem. The macroscale represents a homogeneous material, whereas the mesoscale is decomposed into a polymer based material and inclusions. The microscale represents a step‐growth polymerization mechanism, modelled as a system of multiple growing spheres decomposed into a solid, resin and curing agent material phase. A numerical example shows the capability of the presented framework.
Dynamic fracture with a continuum‐kinematics‐based peridynamic and a phase‐field approach
Authors: Friebertshäuser Kai , Thomas Marita , Tornquist Sven , Weinberg Kerstin , Wieners Christian
Published: March 2023

The notion of dynamic fracture with continuum‐kinematics‐based peridynamics is presented in this work. A geometrically precise version of peridynamics called continuum‐kinematics‐based peridynamics adds surface‐ or volume‐based interactions to the traditional peridynamic bonds, accurately capturing the finite deformation kinematics. The point families produced from the horizon of the material points are used to construct the surfaces and volumes taken into account for these non‐local interactions.

In continuum kinematics‐based peridynamics, the traditional bond‐stretch damage technique is insufficient for fracture. Due to the loss of strength in the internal force densities of the material points, it is now extended to the surface‐ and volume‐based interactions by new failure factors. Numerical examples demonstrate that the proposed approach effectively manages crack propagation, impact damage, and spontaneous crack initiation under dynamic loading circumstances with large deformations. When the results are compared to phase‐field calculations, there is a remarkable agreement concerning the damage patterns.
A particle‐continuum coupling method for amorphous polymers with multiple particle‐based domains
Authors: Torres Huamani David , Zhao Wuyang , Pfaller Sebastian
Published: March 2023

This contribution presents a partitioned‐domain particle‐continuum coupling method for amorphous polymers with multiple particle‐based domains. The coupling method treats the particle‐based domains with molecular dynamics (MD) simulations and the continuum domain discretized by the Finite Element (FE) method. In the continuum domain, a viscoelastic‐viscoplastic (VE‐VP) constitutive model derived from MD simulation results of the polymer at molecular resolution is employed. The effects of the minimum distances between the domains, the distribution and the number of the MD domains as well as the strain rates are studied under uniaxial tension. This method is a precursor for multiscale simulations of polymer‐based nanocomposites (PNC).
Parametric Stability Score for Local Solutions of Constrained Parametric Nonlinear Programs
Authors: Mykhailiuk Ivan , Büskens Christof
Published: March 2023

Nonlinear optimization problems arise in the context of many engineering processes and other real‐world applications. Depending on the complexity of modeled phenomena and constraints, such problems can feature multiple local solutions of different nature. Primarily, the quality of a solution is measured by the value of an objective function, and hence, one aims to find a global optimum. In many cases, however, additional criteria arise. For instance, nonlinear programs, in addition to decision variables, might depend on parameters undergoing perturbations. Such disturbances might be caused by noisy measurement data, changes in the environment in a real‐time setting or other factors. In this case, apart from good optimality, a practitioner might be interested in the behaviour of a solution under changes in parameters. Recently, the parametric stability score was introduced as a quality measure for solutions of unconstrained problems with respect to the influence of parameter perturbations. In this paper, we extend the concept to constrained optimization problems. The score is defined as the largest magnitude of a perturbation for which the perturbed solution does not deviate from the nominal one beyond an allowed tolerance. Our work is based on the results of parametric sensitivity analysis. This framework enables us to give a formal definition of the parametric stability score and provides tools for its efficient numerical approximation. We illustrate the approach with an example and discuss possible application scenarios for the concept.
A phase field model for fractures in ice shelves
Authors: Sondershaus Rabea , Humbert Angelika , Müller Ralf
Published: March 2023

Ice shelves are large floating ice masses, that are formed when glaciers are becoming afloat at the margin of ice sheets. One dominating mass loss mechanism of ice shelves is calving, describing the detachment of icebergs at the front. Ice shelves stabilize inland ice glaciers due to buttressing. If the stabilizing effect of an ice shelf vanishes because of disintegration or thinning, the corresponding glacier accelerates resulting in sea level rise.

To describe calving and disintegration of ice shelves, it is important to investigate fracture propagation in ice. A powerful method in fracture mechanics is the phase field method which is based on Griffith's theory. It approximates cracks in a diffuse manner by using a continuous scalar field. We propose a phase field fracture model for ice considering its characteristic material properties. The material behavior of ice depends on the considered time scales. On short time scales it behaves like a solid and while it acts like a fluid on long time scales, which classifies it as a viscoelastic material of Maxwell type. This has been verified by observations. The phase field method allows us to simulate typical fracture situations of ice shelves in Antarctica and Greenland.
Extension of the stimulus expansion model for photo‐thermo‐sensitive hydrogels
Authors: Mählich Daniel , Ehrenhofer Adrian , Wallmersperger Thomas
Published: March 2023

The stimulus expansion model uses the analogy of thermal expansion in order to model the mechanical swelling behavior of a polymer gel. In the current work, we present an approach to extend the stimulus expansion model for photo‐thermo‐sensitive hydrogels. We describe the swelling behavior by using the stimulus properties, in our case light, as input values and the volume change of the hydrogel as the result by physical coherences. Further, we consider the energy conversion from light into heat within the polymer gel, due to absorption by particles. This phenomenon is considered by an energy balance which depicts the energy input by applying Lambert‐Beer's law. for the absorption of light. By evaluating the energy balance, we can calculate the light dependent temperature increase of the thermo‐sensitive hydrogel. Afterwards, the hydrogel's swelling is modeled by using the thermal expansion analogy. This detailed description of the stimulus behavior allows to study a hydrogel composite without having specific experimental data for this certain combination, but for all the involved components. Furthermore, the time‐dependent stimulus behavior of the considered sample is shown. Based on this approach, the effect of light power variation, particle volume fraction variation and different ambient temperature is studied.
Influence of pore‐structure characteristics on the mechanical properties of open‐porous cellular materials
Authors: Aney Shivangi , Ratke Lorenz , Milow Barbara , Rege Ameya
Published: March 2023

The influence of the pore structure characteristics on the macroscopic mechanical properties of open‐porous cellular materials has been computationally investigated in this contribution. While the effects of the pore‐size distribution on the macroscopic mechanical response of open‐porous cellular materials have been studied previously, the investigations regarding the effects of the pore structure characteristics are relatively scarce. The pore walls of open porous cellular materials are often modelled as beams and the pore wall structure is assumed to have a constant cross section. Although this assumption is valid for a large class of materials, insights into the influence of this assumption on the calculations of the properties of those materials that exhibit a rather pearl‐necklace‐like pore wall morphology are described in this paper. On comparing the simulation results for a corrugated pore‐wall with that having a constant cross‐section, it is observed that the maximal stresses in the pore wall may differ significantly.
Preconditioning for the integration of a spatiotemporal pharmacodynamic system
Authors: Duintjer Tebbens Jurjen , Lanzendörfer Martin , Matonoha Ctirad , Papáček Štěpán
Published: March 2023

We address efficient modeling of the intracellular action of a drug binding to the nuclear pregnane X receptor. The binded complex enters the cell nucleus and acts on DNA, resulting in enhanced production of an enzyme which metabolizes, among others, co‐administered drugs. Pharmacodynamic modeling is traditionally based on a compartmental approach, which simplifies the complex processes in the human body through the definition of a small number of compartments representing organs, tissues, cells, cytoplasm or abstract units. Inside a compartment, the concentrations of all substances are assumed to be distributed homogeneously, i.e. there is no spatial dependence. They lead to a system of ODEs for the time‐dependence of the concentrations of the active substances. We will present an extension of a model from the literature for the action of the tuberculose‐drug Rifampicin. The extension consists of a first attempt to add spatial resolution for substances that are active in the cytoplasm. Spatial resolution can be benecifial to analyze important issues like, among others, local exceeding of toxic drug levels, delay of transport and drug‐drug interactions. We address efficient solution of the linear systems arising when numerically integrating the resulting PDE's and consider some preconditioning techniques based on properties of the underlying biochemical network.
Forerunners of the power iteration method in the 16th and 18th centuries
Authors: Ullrich Peter
Published: March 2023

The power iteration method for determining eigenvectors is usually credited to Richard von Mises (1883–1953) and Hilda Pollaczek‐Geiringer (1893–1973). But their 1929 article was declared a “Zusammenfassender Bericht” (= “Summary report”), not a research paper. It is therefore not surprising that this method or a least its basic ideas can already be found in several publications from mechanics, applied and even pure mathematics since the last decades of the 19th century.

Special cases of the power iteration method are documented in even older texts. The first example is the algorithm that the constructor of astronomical clocks and globes Jost Bürgi (1552–1632) invented in the 1580ies for the approximation of values of the sine function. In the second text, of 1747, the organist, composer and music theorist Christoph Gottlieb Schröter (1699–1782) gave simultaneous approximations for the first 12 natural powers of the 12th root of 2 in order to divide a monochord according to the equal temperament scale.
A two‐surface damage‐plasticity model based on a Drucker—Prager yield criterion
Authors: Zhang Jian , Brepols Tim , Reese Stefanie
Published: March 2023

A gradient‐extended two‐surface damage‐plasticity model based on a von Mises yield criterion has been proposed by [1, 2], which can be flexibly adapted to (quasi‐)brittle‐like, ductile‐like, or various material behaviors in between. However, the von Mises yield criterion does not take into account the effect of hydrostatic pressure, therefore it can hardly model the failure behavior of pressure‐sensitive materials such as geomaterials and some metals. For this reason, a pressure‐dependent two‐surface damage‐plasticity model based on the Drucker‐Prager yield criterion is proposed in the current work, and the nonlinear hardening is also included. Plasticity and damage are treated as distinct but coupled dissipative phenomena by a two‐surface approach. Furthermore, the numerical implementation of the Drucker‐Prager yield criterion is discussed in this study, and the return mapping procedures of the smooth portion and the vertex of the cone are discussed in detail.
Averaging techniques for microstructures with localization bands due to damage progression
Authors: Simon Jaan-Willem , Poggenpohl Lukas , Holthusen Hagen
Published: March 2023

In multiscale analysis, homogenization methods are needed to up‐scale the micromechanical response obtained from investigating the underlying microstructure to the next higher scale. The standard homogenization schemes are based on volume averaging over the entire microstructure following Hill's approach, which requires that the virtual energies generated on the two involved scales equalize. However, these standard homogenization schemes are not applicable to softening phenomena due to localization, and representativeness of the considered microscale volume is lost. One way to overcome these drawbacks is to perform the volume averaging only within the localizing failure zone. Thereby, representative results can be achieved even in the softening region. In this paper, we apply the failure zone homogenization approach to both, mode I and mode II loading scenarios, as well as mixed‐mode loading of long fiber reinforced plastics. For an accurate description of material failure within the epoxy matrix, a scalar damage model at large strains with gradient enhancement is used, such that the obtained results are mesh‐independent. As a result, we show that for all considered cases representative volume element (RVE) sizes can be determined by using the failure zone homogenization scheme. Nevertheless, the energy distributions of all involved mechanisms have to be considered carefully in order to allow generalizations.
Consideration of nonlinear multipoint constraints in finite element analyses based on a master‐slave elimination scheme operating at the global level
Authors: Boungard Jonas , Wackerfuß Jens
Published: March 2023

A method to consider nonlinear multipoint constraints in finite element analysis based on a master‐slave elimination scheme operating at the global level is presented. We focus on systems with nonlinear constraints in which the number of constraints is of the same order of magnitude as the number of degrees of freedom. Therefore, we rely on the master‐slave elimination which gives us the huge benefit of drastically reducing the problem size. In the literature the presented master‐slave elimination schemes for linear constraints are based on the manipulation of the system equations (global level), but the master‐slave elimination schemes for nonlinear constraints are based on manipulation of the element formulation (local level). In contrast to that we use a global approach for which the nonlinear constraints are applied directly on the system equations in analogy to linear constraints. Thus, the method is independent of the underlying element formulation and the type of constraints which makes it more flexible.
Numerical modelling of stress‐strain response and deformation‐induced martensite in metastable austenitic stainless steels under monotonic tensile loading
Authors: Thammineni Hari Kisan , Zhu Tong , Smaga Marek , Beck Tilmann , Müller Ralf
Published: March 2023

A constitutive model describing the deformation‐induced martensite transformation in metastable austenitic CrNi steels is presented. In line with the previous work of Stringfellow et al. [1], the material is considered to have a composite response of the underlying austenite and the evolving martensite phases. The stresses and strains in the individual phases are described using viscoplastic models. The effective properties of the material are then computed by a homogenization method. Strain hardening in the individual phases is represented using separate flow rules. Furthermore, based on the plastic strain in the austenitic phase, a transformation kinetics model describes the evolution of the martensite volume, in the two‐phase composite.

A numerical implementation of the model is done in the finite element program FEAP [2]. The parameters in model are identified by experimental data using the least‐squares optimization. Finally, some results are presented using an illustrative boundary value problem of a structured surface.
A phenomenological model to describe cracking and fibre pull‐out in ultra high‐performance fibre reinforced concrete
Authors: Gietz Lena , Kowalsky Ursula , Dinkler Dieter
Published: March 2023

In ultra‐high performance concrete (UHPC) embedded micro steel fibres increase the ductility and improve the post cracking load‐bearing behaviour under tensile loading. For an efficent and economical dimensioning of components, especially for fatigue susceptible structures, it is necessary to characterise the crack‐bridging load‐bearing effect of the micro steel fibres and the associated processes taking place in the intersection between both material components. Thus, the development of model equations to predict the deformation and damage behaviour of UHPFRC with numerical simulations on the macro‐level is very useful. In the contribution, a material model, which describes the phenomenological damage processes of the composite material, is presented. The numerical realisation with the finite element method applies a hybrid‐mixed element formulation, where a direct coupling with the material model is performed. Numerical studies of the material behaviour of UHPFRC are presented by means of an illustrative example.
Methods of Model Order Reduction for Coupled Systems Applied to a Brake Disc‐Wheel Composite
Authors: Matter Fabian , Iroz Igor , Eberhard Peter
Published: March 2023

In this contribution, investigations on model order reduction for coupled systems composed from components of a passenger car are shown. In today's development processes, the simulation of mechanical components is indispensable and large Finite Element models are often used for this purpose. For the calculation of time‐domain or frequency‐domain analyses, for example, a lot of computing power is required. However, with the application of model order reduction methods, this effort can be reduced, but this results in a trade‐off between the reduction error and the computational time. Since the computation of reduction bases for complete systems can be computationally expensive, it is of interest to be able to reduce components individually and then assemble them into a reduced overall model. This can result in both, a saving of computational effort when creating the bases, as well as a saving of the required memory space. Furthermore, there are many possible combinations of components in the modular systems of today's automotive industry, which emphasizes the model order reduction by parts and not by assemblies. In this work, methods of model order reduction for coupled systems are presented and will be tested on components in the chassis of a sports car. Therefore, an assembly consisting of a brake disc and wheel rim together with the wheel hub are investigated. For this purpose, the eigenmodes and transfer functions of the overall model, the reduced overall model and the assembly built from individual reduced bodies are compared.
Impact of electrical percolation on mechanical, thermal and flame properties of carbon filler‐epoxy composites
Authors: Rashmi  , Poornima  , Sundara Rajan J.
Published: March 2023

Hybrid combination of carbon fillers is utilized in an epoxy matrix to enhance DC/AC conductivity and dielectric constant. Influence at electrical percolation on mechanical strength, thermal stability, co‐efficient of thermal expansion (CTE), and flame properties have been investigated since proper balance of the properties is critical. Multiwalled carbon nanotube and graphene nanoplatelets of different weight proportions are incorporated in epoxy matrix to understand their impact of electrical, mechanical and thermal properties. It is observed that weight fraction of the carbon fillers at electrical percolation tends to deteriorate the mechanical and flame properties, minimally influences thermal stability while decreasing the CTE. The weight fractions below the electrical percolation are observed to enhance mechanical and flame properties as compared to percolation level. Though the formation of network of carbon fillers is responsible for enhancement of electrical conduction and CTE, the synergy of carbon fillers is not evident in mechanical and flame properties due to dominating influence of aspect ratio, orientation, and alignment. DC conductivity of 3 × 10−6 S/m, AC conductivity of 4 × 10−2 S/m at 8 MHz is observed at electrical percolation. However, composite reveals 5% to 10% reduction in mechanical strength, while the thermal stability and glass transition (126°C) are minimally affected at percolation. Co‐efficient of thermal expansion improves to 2 × 10−6/°C and heat deflection temperature increases to 140°C. Flame properties reveal divergent trends. The need for proper balance of electrical, thermal and mechanical properties at electrical percolation is emphasized.
The multifaceted challenges of teaching from home: A study of schoolteachers' well‐being during the COVID‐19 pandemic
Authors: Bhattacharya Anindita , Tandon Ankita
Published: March 2023

This study examined perceived needs, well‐being, work/nonwork conflict and demands, and coping mechanisms among government and private schoolteachers in India while working from home during the COVID‐19 pandemic. We employed a mixed method design, collecting 161 quantitative responses using questionnaires and 121 qualitative responses using open‐ended questions. These were analyzed using inferential statistics and thematic analysis, respectively. Results highlight the negative impact of work/nonwork conflict on well‐being. The missing work‐home boundaries resulted in extended work hours, unorganized routines, and simultaneous work/nonwork demands. We describe the multifaceted nature of operational, pedagogical, and technological challenges faced by schoolteachers. We suggest psychological and operational resources and support mechanisms that can be developed at the family, school administration, and policy levels. Further, customized bundles of solutions are needed to address the variability in the challenges faced.
Synthesis of thin‐film materials using nonthermal plasma at a higher degree of dissociation
Authors: Cech Vladimir , Branecky Martin
Published: March 2023

Lower flow rates of precursor molecules are favorable for the synthesis of thin‐film materials using nonthermal plasma at a higher degree of dissociation and sufficiently high deposition rate. These deposition conditions can be used for both continuous wave (CW) and pulsed plasmas and result in higher consumption of precursor molecules, which is beneficial for industrial applications due to cost reduction. A wider range of power can be used to control the chemical and physical properties of thin‐film materials based on power‐dependent plasma chemistry. Hydrogenated amorphous silicon carbide films deposited in CW and pulsed plasma are used as an example. The different kinetics of film growth and the role of self‐bias voltage in both types of plasma are discussed.
Prediction of upgrade to clinically significant prostate cancer in patients under active surveillance: Performance of a fully automated AI‐algorithm for lesion detection and classification
Authors: Oerther Benedict , Engel Hannes , Nedelcu Andrea , Schlett Christopher L. , Grimm Robert , von Busch Heinrich , Sigle August , Gratzke Christian , Bamberg Fabian , Benndorf Matthias
Published: March 2023

Background

Multiparametric MRI (mpMRI) improves the detection of aggressive prostate cancer (PCa) subtypes. As cases of active surveillance (AS) increase and tumor progression triggers definitive treatment, we evaluated whether an AI‐driven algorithm can detect clinically significant PCa (csPCa) in patients under AS.

Methods

Consecutive patients under AS who received mpMRI (PI‐RADSv2.1 protocol) and subsequent MR‐guided ultrasound fusion (targeted and extensive systematic) biopsy between 2017 and 2020 were retrospectively analyzed. Diagnostic performance of an automated clinically certified AI‐driven algorithm was evaluated on both lesion and patient level regarding the detection of csPCa.

Results

Analysis of 56 patients resulted in 93 target lesions. Patient level sensitivity and specificity of the AI algorithm was 92.5%/31% for the detection of ISUP ≥ 1 and 96.4%/25% for the detection of ISUP ≥ 2, respectively. The only case of csPCa missed by the AI harbored only 1/47 Gleason 7a core (systematic biopsy; previous and subsequent biopsies rendered non‐csPCa).

Conclusions

AI‐augmented lesion detection and PI‐RADS scoring is a robust tool to detect progression to csPCa in patients under AS. Integration in the clinical workflow can serve as reassurance for the reader and streamline reporting, hence improve efficiency and diagnostic confidence.
Clinical and molecular determinants of PSA response to bipolar androgen therapy in prostate cancer
Authors: Caputo Sydney A. , Hawkins Madeline , Jaeger Ellen B. , Fleming William , Casado Crystal , Manogue Charlotte , Huang Minqi , Lieberman Alex , Light Malcolm , Sussman Isabelle P. , Miller Patrick , Barata Pedro C. , Lewis Brian E. , Layton Jodi Lyn , Ledet Elisa M. , Antonarakis Emmanuel S. , Sartor Oliver
Published: March 2023

Background

Bipolar androgen therapy (BAT) is a novel therapy known to be effective in a subset of men with metastatic castrate resistant prostate cancer (mCRPC). A better understanding of responders and nonresponders to BAT would be useful to clinicians considering BAT therapy for patients. Herein we analyze clinical and genetic factors in responders/nonresponders to better refine our understanding regarding which patients benefit from this innovative therapy.

Methods

mCRPC patients were assessed for response or no response to BAT. Patients with PSA declines of greater than 50% from baseline after 2 or more doses of testosterone were considered to be responders. Whereas, nonresponders had no PSA decline after 2 doses of testosterone and subsequently manifest a PSA increase of >50%. Differences between these two groups of patients were analyzed using clinical and laboratory parameters. All patients underwent genomic testing using circulating tumor DNA (ctDNA) and germline testing pre‐BAT.

Results

Twenty five patients were nonresponders and 16 were responders. Baseline characteristics between nonresponders and responders varied. Responders were more likely to have had a radical prostatectomy as definitive therapy and were more likely to have been treated with an androgen receptor (AR) antagonist (enzalutamide or apalutamide) immediately before BAT (compared to abiraterone). Duration of prior enzalutamide therapy was longer in responders. Nonresponders were more likely to have bone‐only metastases and responders were more likely to have nodal metastases. Assays detected ctDNA AR amplifications more often in responding patients. Responders trended toward having the presence of more TP53 mutations at baseline.

Conclusions

BAT responders are distinct from nonresponders in several ways however each of these distinctions are imperfect. Patterns of metastatic disease, prior therapies, duration of prior therapies, and genomics each contribute to an understanding of patients that will or will not respond. Additional studies are needed to refine the parameters that clinicians can utilize before choosing among the numerous treatment alternatives available for CRPC patients.
Discovery of triphenylphosphonium (TPP)‐conjugated N‐(1,1′‐biphenyl)‐2‐yl aliphatic amides as excellent fungicidal candidates
Authors: Wang Jiayao , Liu Huihui , Jiang Jiazhen , Liu Xuelian , Zhou Tianyou , Li Jia‐Qi , Xiao Yumei , Qin Zhaohai
Published: March 2023

BACKGROUND

Succinate dehydrogenase inhibitors (SDHIs) are the fastest growing agricultural fungicides at present, but their rapidly growing resistance is a serious problem for their application. Previously, we screened out a fungicidal lead compound CBUA‐TPP (1) through triphenylphosphonium (TPP)‐driven mitochondrial‐targeting strategy. The targeting led to the rapid accumulation of 1 in mitochondria and the saturation inhibition of complex II in a short time, resulting in electron leakage and the explosion of reactive oxygen species (ROS). However, the contribution of biphenyl‐2‐amines to the activity of these compounds and their structure–activity relationship are still unknown.

RESULTS

Two series of CBUA‐TPP (1) analogues (series 2 and 3) were designed and synthesized. The bioassay results indicated that series 2 compounds generally showed much higher fungicidal activities than series 3, suggesting the crucial contribution of the biarylamine module in these targeted molecules and the pyridinyl substitution of phenyl is unfavorable to their activities. Interestingly, these two series of compounds displayed almost opposite substituent effects. Several compounds showed excellent fungicidal activities in vitro, among which compound 2‐1 exhibited excellent field control efficacy on potato late blight.

CONCLUSION

By optimizing the lead compound, the contribution of biarylamine in CBUA‐TPP (1) analogs to the fungicidal activity is clarified. Several compounds, represented by 2‐1, have great potential as fungicide candidates. They exhibit high and broad‐spectrum fungicidal activities and are highly effective against common pathogenic fungi infecting vegetables and fruits both in vitro and field control. It not only provided a new choice for controlling these diseases, but its low resistance tendency also provided a better scheme for resistance management. © 2023 Society of Chemical Industry.
Use of the 1.1 mm cryoprobe through the radial EBUS GS (without the need for a bronchial blocker) to obtain samples safely in diagnosing peripheral pulmonary lesions (PPL)
Authors: Herath Samantha
Published: March 2023

Cryobiopsy for peripheral pulmonary lesions suspected of lung cancer is gaining popularity due to the larger non‐crushed samples capable of an array of molecular testing. However, the method of performing this procedure so far had been resource‐intensive and time‐consuming limiting the procedure to tertiary centres. Having to remove the cryobiopsy en masse with the bronchoscope was the main issue that hindered the safety of the procedure. We report two cases where the 1.1 mm cryoprobe was used and the cryobiopsy was extracted through the Radial EBUS GS whilst the bronchoscope remained in the bronchial tree, with excellent control of bleeding, due to the tamponading of the GS as well as the ability to attend to bleeding as soon as it occurred, due to the bronchoscope being inside the airway. This method of obtaining the cryobiopsy through the GS and keeping the bronchoscope in the airway improved the safety of cryobiopsy for PPL. Further studies are required to assess the consistency of yield and safety of this method.
Nonlinear disturbance observer based multiple‐model adaptive explicit model predictive control for nonlinear MIMO system
Authors: Dutta Lakshmi , Kumar Das Dushmanta
Published: March 2023

In this article, a nonlinear disturbance observer‐based multiple‐model adaptive explicit model predictive control (NDO‐MMAEMPC) scheme is developed for a nonlinear MIMO system with parametric uncertainty as well as an external disturbance. The proposed method manages external disturbances without affecting the degree of smoothness of the control signals. Further, to cope with the unknown system uncertainty, blending‐based adaptive identification schemes are used for the same class of systems. For each identification model, an explicit nonlinear model predictive controller is computed off‐line for the corresponding model in advance, which saves computation power during operation. The generated control inputs from the set of explicit controllers are being blended online using adaptive weight. An extended Kalman filter algorithm is employed for the estimation of the unavailable states of the nonlinear system. Using an aerodynamic laboratory setup, the effectiveness of the proposed control algorithm is verified.
Robust control scheme based on an uncertainty and disturbance estimator for a quadrotor with motor failures
Authors: Betancourt Julio , Balaguer Vicente , Castillo Pedro , García Pedro , Lozano Rogelio
Published: March 2023

This paper proposes a new robust fault tolerant control architecture based on a disturbance observer. The control architecture is composed of a nominal controller and a rotor's fault observer capable to identify and estimate motors' degradation performance. Besides, is designed for a quadrotor vehicle and validated in critical and noncritical motors' failures. For both failure cases, each motor performance is analyzed to counteracted the failure and restore the system stability. If the practical stability is not recovered (critical case) a control reconfiguration is performed for safe landing. Experimental tests are carried out in real time to illustrate the effectiveness of the proposed architecture when confronting the stability of the system with aggressive disturbances or uncertainties.
Synthesis of Visible Light Excitable Carbon Dot Phosphor‐Al2O3Hybrids for Anti‐Counterfeiting and Information Encryption
Authors: Lu Dong , Lu Ke , Wen Hong‐Tao , Wei Zhan , Bianco Alberto , Wang Gui‐Gen , Zhang Hua‐Yu
Published: March 2023

The preparation of room temperature phosphorescent carbon dots still faces great challenges, especially in the case of carbon dots endowed of visible‐light excitable room temperature phosphorescence (RTP). To date, a limited number of substrates have been exploited to synthesize room temperature phosphorescent carbon dots, and most of them can emit RTP only in solid state. Here, the synthesis of a composite obtained from the calcination of green carbon dots (g‐CDs) blended with aluminum hydroxide (Al(OH)3) is reported. The resultant hybrid material g‐CDs@Al2O3exhibits blue fluorescence and green RTP emissions in an on/off switch process at 365 nm. Notably, this composite manifests strong resistance to extreme acid and basic conditions up to 30 days of treatment. The dense structure of Al2O3formed by calcination contributes to the phosphorescent emission of g‐CDs. Surprisingly, g‐CDs@Al2O3can also emit yellow RTP under irradiation with white light. The multicolor emissions can be employed for anti‐counterfeiting and information encryption. This work provides a straightforward approach to produce room temperature phosphorescent carbon dots for a wide range of applications.
Mesoporous Silica‐Guided Synthesis of Metal–Organic Framework with Enhanced Water Adsorption Capacity for Smart Indoor Humidity Regulation
Authors: Ge Lurong , Feng Yaohui , Xue Yanan , Dai Yanjun , Wang Ruzhu , Ge Tianshu
Published: March 2023

Metal–organic frameworks (MOFs) are promising for indoor humidity regulation due to steep stepwise water uptake and moderate regeneration temperature. Current approaches for performance improvement of MOFs such as impregnating hygroscopic salts and grafting functional groups face the challenge of corrosion and instability. Herein, a template‐guided tuning strategy is proposed to synthesize binary nanocomposite. Highly ordered mesoporous channels of MCM‐41 provide uniform nucleation sites for MOF growth, enabling a 21.5% promotion of specific surface area (3188.14 m2 g−1) and 23.4% improvement of water uptake (1.53 g g−1 at 20°C/90% relative humidity) for the nanocomposite compared with parent MIL‐101(Cr). The fast kinetics and superior stability together guarantee its practical application. Further, a paradigm of continuous indoor humidity regulation driven by sunlight is demonstrated, which realizes smart regulation of the indoor humidity to the human comfort zone (40–60%) with near‐zero energy input.