Numerical determination of the material properties of porous dust cakes

The formation of planetesimals requires the growth of dust particles through collisions. Micron-sized particles must grow by many orders of magnitude in mass. In order to understand and model the processes during this growth, the mechanical properties, and the interaction cross sections of aggregates with surrounding gas must be well understood. Recent advances in experimental (laboratory) studies now provide the background for pushing numerical aggregate models onto a new level. We present the calibration of a previously tested model of aggregate dynamics. We use plastic deformation of surface asperities as the physical model to bring critical velocities for sticking into accordance with experimental results. The modified code is then used to compute compression strength and the velocity of sound in the aggregate at different densities. We compare these predictions with experimental results and conclude that the new code is capable of studying the properties of small aggregates.Comment: Accepted for publication in A&

Concept for modelling the influence of electrode corrugation after calendering on stacking accuracy in battery cell production

Due to the complex process chain in battery cell production, effects of processes on subsequent processes must be evaluated. As challenge in calendering electrodes, corrugation can be observed depending on adjusted parameters. To evaluate the corrugation with regard to the subsequent stacking process accuracy, a concept for modelling the process chain calendering - separation - single sheet stacking is presented. First, an experimental approach for modelling the calendering impact on the electrode sheet geometry after separation is suggested. Finally, a FEM simulation approach for the single sheet stacking process is presented, which is suitable to model impacts from previous processes

Influence of electrode corrugation after calendering on the geometry of single electrode sheets in battery cell production

Calendering is an essential process step in battery cell production. By selective compaction of the material, the performance of the battery cell can be optimized. During processing, corrugations can occur in the machine direction, which are characterized in this article in relation to the material systems LiNi$_{0.8}$Mn$_{0.1}$Co$_{0.1}$O$_2$ (NMC811) and LiNi$_{0.6}$Mn$_{0.2}$Co$_{0.2}$O$_2$ (NMC622) as well as the rate of compaction and the web tension. It is shown that the corrugations are strongly dependent on the rate of compaction. The material system and the web tension show a weaker influence on the corrugation characteristics. Subsequently, single electrode sheets are cut from the coils and their geometry is investigated. It is shown that the corrugation hardly propagates further into the single electrodes, which is explained with the storage time of the electrodes. Rather, the coil bending strongly influences the electrode sheet geometry. It is shown that the position of the conductor tab also has an important influence

Core Formation in Giant Gaseous Protoplanets

Sedimentation rates of silicate grains in gas giant protoplanets formed by disk instability are calculated for protoplanetary masses between 1 M_Saturn to 10 M_Jupiter. Giant protoplanets with masses of 5 M_Jupiter or larger are found to be too hot for grain sedimentation to form a silicate core. Smaller protoplanets are cold enough to allow grain settling and core formation. Grain sedimentation and core formation occur in the low mass protoplanets because of their slow contraction rate and low internal temperature. It is predicted that massive giant planets will not have cores, while smaller planets will have small rocky cores whose masses depend on the planetary mass, the amount of solids within the body, and the disk environment. The protoplanets are found to be too hot to allow the existence of icy grains, and therefore the cores are predicted not to contain any ices. It is suggested that the atmospheres of low mass giant planets are depleted in refractory elements compared with the atmospheres of more massive planets. These predictions provide a test of the disk instability model of gas giant planet formation. The core masses of Jupiter and Saturn were found to be ~0.25 M_Earth and ~0.5 M_Earth, respectively. The core masses of Jupiter and Saturn can be substantially larger if planetesimal accretion is included. The final core mass will depend on planetesimal size, the time at which planetesimals are formed, and the size distribution of the material added to the protoplanet. Jupiter's core mass can vary from 2 to 12 M_Earth. Saturn's core mass is found to be ~8 M_Earth.Comment: Accepted for publication in Icaru

Model‐Based Optimization of Web Tension Control for the Flexible Cell Stack Assembly of Lithium‐Ion Battery Cells

The transformation toward electromobility presents a significant challenge to the battery cell production processes. It is, therefore, necessary to establish efficient and robust operations and machines to meet the forecasted demand for manufactured cell capacity. Currently, the development and ramp-up phases of production machines, especially for cell stack assembly, are characterized by high material scrap rates and large personnel expenses. Aspects such as the web tension of electrodes or separator materials during separation and stack assembly have a significant influence on the subsequent intermediate product properties, and therefore present a key challenge. Herein, the optimal methodology for the web tension control of electrode materials is determined via a model-based approach by the means of a digital twin. The focus is hereby set on a production machine for the flexible cell stack assembly. Appropriate control methods are implemented and validated on the real system, thus reducing material scrap rates and overall costs. The control of the web tension by means of an unwinder and material storage was found to be optimal on the basis of the model and confirmed experimentally

About prediction method for work resource of combustion cameras ships of forced high-speed diesels pistons taking into account engine Operation model

В работе проанализированы существующие методики прогнозирования длительной прочности поршней быстроходных дизелей с учетом усталости, ползучести и их комплексного влияния. Показано, что на процесс ползучести материала в реальных конструкциях поршней существенное влияние оказывает длительность цикла нагружения материала. Отмечено, что скорость ползучести материала в произвольный момент времени также зависит от ранее накопленной деформации ползучести. параметры нагружения материала от цикла к циклу будут изменяться. Обосновано, что прогнозирование длительной и термоусталостной прочности поршней форсированных быстроходных дизелей следует осуществлять с учетом комплексного влияния усталости и ползучести на процесс накопления повреждений. Разработана методика оценки длительной и термоусталостной прочности поршня с учетом отмеченного комплексного влияния указанных процессов. Проведен анализ влияния истории нагружения поршня быстроходного дизеля на долговечность кромки камеры сгорания. Разработана методика, позволяющая прогнозировать время до разрушения кромки камеры сгорания на начальных стадиях проектирования двигателя с учетом модели его эксплуатации.The paper analyzes the existing methods for predicting the long-term strength of high-speed diesel eng ines pistons, taking into account fatigue, creep an d their complex effect. It is shown that the material creepprocess is significantly affected by the duration of the material loading cycle in real piston structures. It is noted that at an arbitrary time the material creep rate also depends on the previously accumulated creep deformation. The material loading parameters will change from cycle to cycle. It has been substantiated that the prediction of the long-term and heat-fatigue strength of the forced high-speed diesel engines pistons should be carried out taking into account the complex effect of fatigue and creep on the damage accumulation process. A method has been developed for estimating the long-term and thermal fatigue strength of the pisto n, taking into account the noted complex effect of these processes. The analysis is carried out the lo ading history influence of a high-speed diesel piston on the comb ustion chamber edge durability. A technique has been developed that makes it possible to predict the time to destruction of the of the combustion chamber edge at the initial stages of engine design, taking into account the model of its operation

The RCX extension hub: a resource for implementations extending the R adaption of the cytoscape exchange format

Public repositories provide access to biological networks for investigations, and subsequently serve to distribute the network encoded biomedical and even clinically relevant results. However, inclusion of complementary information requires data structures and implementations customized to the integrated data for network representation, usage in supporting application, and extending analysis functionality. Partitioning of this information into individual aspects of a network facilitates compatibility and reusability of the network-based results, but also requires support and accessibility of the extensions and their implementations. The RCX extension hub offers overview and access to extensions of the Cytoscape exchange format implemented in R. The hub supports the realization of self-customized extension through guides, example implementations, and a template for the creation of R extension packages