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Advances in Manufacturing 2022年第2期10卷 235-249页

作者： Ekrem Oezkaya Sebastian Michel dirk Biermann Institute of Machining Technology Dortmund University of Technology(TU Dortmund)Dortmund 44227Germany

An experimental analysis regarding the distribution of the cutting fluid is very difficult due to the inaccessibility of the contact zone within the bore ***,suitable simulation models are necessary to evaluate new tool designs and optimize drilling *** this paper the coolant distribution during helical deep hole drilling is analyzed with high-speed *** particles are added to the cutting fluid circuit bya developed high-pressure mixing *** the evaluation of suitable particle size,particle concentration and coolant pressure,a computational fluid dynamics(CFD)simulation is validated with the experimental *** comparison shows a very good model quality with a marginal difference for the flow velocity of 1.57%between simulation and *** simulation considers the kinematic viscosity of the *** results show that the fluid velocity in the chip flutes is low compared to the fluid velocity at the exit of the coolant channels of the tool and drops even further between *** velocity and the flow pressure directly at the cutting edge decrease to such an extent that the fluid cannot generate a sufficient cooling or *** the CFD simulation a deeper understanding of the behavior and interactions of the cutting fluid is *** on these results further research activities to improve the coolant supply can be carried out with great potential to evaluate new tool geometries and optimize the machining process.

关键词： Computational fluid dynamics(CFD)analysis:Viscosity-Tracermicro particles Fluidbehavior Helical deep hole drilling

Assessment of wear micromechanisms on a laser textured cemented carbide tool during abrasive-like machining by FIB/FESEM

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Friction 2021年第3期9卷 656-664页

作者： Shiqi FANG dirk BÄHRE Luis LLANES Institute of Production Engineering Saarland UniversitySaarbrücken 66123Germany CIEFMA-Department of Materials Science and Engineering EEBE-Campus Diagonal BesòsUniversitat Politècnica de CatalunyaBarcelona 08019Spain

The combined use of focused ion beam(FIB)milling and field-emission scanning electron microscopy inspection(FESEM)is a unique and successful approach for assessment of near-surface phenomena at specific and selected *** this study,a FIB/FESEM dual-beam platform was implemented to docment and analyze the wear micromechanisms on a laser-surface textured(LST)hardmetal(HM)*** particular,changes in surface and microstructural integrity of the laser-sculptured pyramids(effective cutting microfeatures)were characterized after testing the LST-HM tool against a steel workpiece in a workbench designed to simulate an external honing *** was demonstrated that:(1)laser-surface texturing does not degrade the intrinsic surface integrity and tool effectiveness of HM pyramids;and(2)there exists a correlation between the wear and loading of shaped pyramids at the local ***,the enhanced performance of the laser-textured tool should consider the pyramid geometry aspects rather than the microstructure assemblage of the HM grade used,at least for attempted abrasive applications.

关键词： focused ion beam(FIB) field-emission scanning electron microscopy inspection(FESEM) cemented carbides laser surface texturing abrasive machining processes wear

Experimental and Theoretical Study on Piezoresistive Behavior of Compressible Melamine Sponge Modified by Carbon-based Fillers

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Chinese Journal of Polymer Science 2022年第11期40卷 1503-1512页

作者： Xiao-Ling Luo dirk W.Schubert Institute of Polymer Materials Friedrich-Alexander-University Erlangen-NurembergMartensstr.7Erlangen91058Germany KeyLab Advanced Fiber Technology Bavarian Polymer InstituteDr.Mack-Strasse 77Fürth90762Germany

High-performance compression sensors have been playing an increasingly important role in human motion detection,health monitoring and human-machine interfaces over recent ***,it remains a great challenge to develop theoretical models providing practical guidance to the sensor ***,carbon black(CB),carbon nanotubes(CNTs)and graphene nanoplatelets(GNPs)were respectively incorporated into porous melamine sponges by a facile approach of dip-coating to fabricate compression *** compression-resistance tests show that the compressibility,stability and piezoresistive sensitivity of sensors could be tailored by the filler type and concentration.A model considering the number of conductive pathways(NCP)is given to describe the relationship between the resistance change and applied compression,showing extremely good agreement with the experimental ***,the correlation between the equivalent filler volume fraction and conductivity is described by the other two models proposed by McLachlan and Kirkpatrick,revealing the electrical percolation thresholds(Φc)for the conductive systems under *** the three fillers,CB particles endowed the composite with the best piezoresistive sensitivity but the largestΦc due to its small size and aspect ratio.A combination of experimental study and theoretical model opens up a way of further understanding the piezoresistive sensing behavior as well as optimizing the electrical property and piezoresistivity of compressive conductive polymer composite.

关键词： Compression sensor Melamine sponge Model Piezoresistivity

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维生素D代谢物有助于母猪分娩过程

国外畜牧学（猪与禽） 2024年第1期44卷 12-13页

作者： Katia Pedrosa Kathrin Buehler Jan dirk Van der Klis 张相鑫(译) 王晶晶(校) 孟祥光(制图) 不详

维生素D是一种重要的营养物质,母猪在妊娠后期和哺乳期对其需要量非常高。本文概述了维生素D对母猪分娩的影响,提出可以在常规添加维生素D之外补充1,25-二羟基维生素D3糖苷,以缩短分娩时间,减少分娩过程中的人为干预,减少死胎数。

关键词：维生素D 1 25-二羟基维生素D3糖苷分娩

High throughput screening of localised and general corrosion in type 2205 duplex stainless steel at ambient temperature

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International Journal of Minerals,Metallurgy and Materials 2023年第12期30卷 2375-2385页

作者： Yiqi Zhou Sultan Mahmood dirk Lars Engelberg Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China Metallurgy and Corrosion School of MaterialsThe University of ManchesterM139PLManchesterUK Materials Performance Centre The University of ManchesterM139PLManchesterUK

Bipolar electrochemistry is used to produce a linear potential gradient across a bipolar electrode(BPE),providing direct access to the anodic and cathodic reactions under a wide range of applied *** occurrence of pitting corrosion,crevice corrosion,and general corrosion on type 2205 duplex stainless steel(DSS 2205)BPE has been observed at room *** critical pit depth of 10-20μm with a55%-75% probability of pits developing into stable pits at potential from+0.9 to+1.2 V ***(open circuit potential)are *** pit nucleation sites are either within ferritic grains or at the interface between austenite and *** critical conditions for pitting and crevice corrosion are discussed with Epit(critical pitting potential)and Ecre(critical crevice potential)decreasing from 0.87 and 0.80 V *** after150 s of exposure to 0.84 and 0.76 V *** after 900 s of exposure,*** growth kinetics under different applied bipolar potentials and exposure times have been *** ferrite is shown to be more susceptible to general dissolution.

关键词： bipolar electrochemistry duplex stainless steel pitting corrosion pit growth factor crevice corrosion

Development of a Long-Term Operational Optimization Model for a Building Energy System Supplied by a Geothermal Field

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Journal of Thermal Science 2022年第5期31卷 1293-1301页

作者： KÜMPEL Alexander STOFFEL Phillip MÜLLER dirk RWTH Aachen University E.ON Energy Research CenterInstitute for Energy Efficient Buildings and Indoor ClimateAachen 52074Germany

In order to reduce energy consumption and CO_(2) emissions in the building sector, more and more renewable energy sources are integrated into energy systems. Especially geothermal fields combined with heat pumps are able to supply buildings with heat and cold at low carbon emissions. However, using geothermal fields as heat and cold source influences the ground temperature. Consequently, the ground temperature can change dramatically over a building’s lifetime, leading to less efficient operation of the energy system. Therefore, a sustainable operation is required to ensure the long-term efficiency of geothermal fields. In this paper, we develop an optimization model to derive operating strategies for an efficient long-term operation of a building energy system coupled to a geothermal field. The investigated energy system is the main building of the *** Energy Research Center in Aachen, Germany, which includes a heat pump, two boilers, a combined heat, and power unit, a glycol cooler, and a geothermal field with 41 probes. For each component, we develop energy-based sub-models, which are connected to form the overall system. The geothermal field is modeled by using a g-functions approach as well as a simplified resistance-capacitance approach. To achieve short computing times and realize an optimization horizon of several years, the optimization problem is formulated as mixed-integer linear programming(MILP). The developed model is optimized regarding two different objectives: the minimization of energy costs and the minimization of long-term temperature changes in the ground. Conclusions for an efficient and sustainable operation of the field, especially for the cooling supply, can be derived from the optimization results. It is shown that a state of equilibrium should be aimed to achieve an energy-efficient operation, in which the temperature of the field is close to the initial ground temperature.

关键词： geothermal energy building energy systems operational optimization long-term operation

Plausibility in Early Stages of Architectural Design: A New Tool for High-Rise Residential Buildings

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Tsinghua Science and Technology 2009年第3期14卷 327-332页

作者： dirk Donath Danny Lobos Chair of Computer Science in Architecture Faculty of Architecture Bauhaus-UniversityWeimar 99423 Germany

This paper analyzes the problem of the design of envelopes for high-rise isolated residential buildings. The phenomenon of envelope creation appears in the early stages of the architectural design. Variables that influence the final shape and size of such envelopes are then identified. This paper presents the state-of-the-art tools for the current solutions at the commercial and academic/scientific level. The variables identified in this research are the client＇s needs, the urban code and architectural practice, and their specific components for the final creation of a new decision support system tool based on the building information modeling （BIM） software platform, to facilitate the work in the project development and drawing production stages. This tool generates several options for building envelopes according to the parameters required by the city Zoning Planning Commission. These options then lead to deliver reliable data and a geometry that can be analyzed in a timely fashion by the engineers, builders, architects, government, and clients in the early stages of the building＇s design. The results show that use of specific information and communication technologies （ICT） tools in the early stages of a building design helps reduce the working time, increases confidence in the generated solution, and contributes to the exploration of alternatives in a short period of time.

关键词： constraint based design parametric programming urban modeling optimization architectural design

Highly Sensitive Ultrathin Flexible Thermoplastic Polyurethane/Carbon Black Fibrous Film Strain Sensor with Adjustable Scaffold Networks

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Nano-Micro Letters 2021年第4期13卷 159-177页

作者： Xin Wang Xianhu Liu dirk W.Schubert Institute of Polymer Materials Friedrich-Alexander-University Erlangen-NurembergMartensstr.791058 ErlangenGermany National Engineering Research Center for Advanced Polymer Processing Technology Zhengzhou UniversityZhengzhou 450002People’s Republic of China Bavarian Polymer Institute Dr.Mack‑Strasse 7790762 FürthGermany

In recently years,high-performance wearable strain sensors have attracted great attention in academic and ***,a conductive polymer composite of electrospun thermoplastic polyurethane(TPU)fibrous film matrix-embedded carbon black(CB)particles with adjustable scaffold network was fabricated for high-sensitive strain *** work indicated the influence of stereoscopic scaffold network structure built under various rotating speeds of collection device in electrospinning process on the electrical response of TPU/CB strain *** structure makes the sensor exhibit combined characters of high sensitivity under stretching strain(gauge factor of 8962.7 at 155%strain),fast response time(60 ms),outstanding stability and durability(>10,000 cycles)and a widely workable stretching range(0–160%).This high-performance,wearable,flexible strain sensor has a broad vision of application such as intelligent terminals,electrical skins,voice measurement and human motion ***,a theoretical approach was used to analyze mechanical property and a model based on tunneling theory was modified to describe the relative change of resistance upon the applied ***,two equations based from this model were first proposed and offered an effective but simple approach to analyze the change of number of conductive paths and distance of adjacent conductive particles.

关键词： Strain sensor Electrospinning Electronic skin Fitting model

Efficient Dynamic Floor Field Methods for Microscopic Pedestrian Crowd Simulations

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Communications in Computational Physics 2014年第6期16卷 264-286页

作者： dirk Hartmann Peter Hasel Siemens AG Corporate Technology80200 MunichGermany

Floor field methods are one of the most popular medium-scale navigation concepts in microscopic pedestrian *** introduced dynamic floor field methods have significantly increased the realism of such simulations,*** of spatio-temporal patterns of pedestrian densities in simulations with real world *** methods update floor fields continuously taking other pedestrians into *** implies that computational times are mainly determined by the calculation of floor *** this work,we propose a new computational approach for the construction of dynamic floor *** approach is based on the one hand on adaptive grid concepts and on the other hand on a directed calculation of floor fields,*** calculation is restricted to the domain of *** both techniques the computational complexity can be reduced by a factor of 10 as demonstrated by several realistic *** on-line simulations,a requirement of many applications,are possible for moderate realistic scenarios.

关键词： Pedestrian dynamics cellular automata adaptive grids floor field methods fast marching method navigation.

Cloud-Based Optimal Control of Individual Borehole Heat Exchangers in a Geothermal Field

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Journal of Thermal Science 2022年第5期31卷 1253-1265页

作者： STOFFEL Phillip KÜMPEL Alexander MÜLLER dirk RWTH Aachen University E.ON Energy Research CenterInstitute for Energy Efficient Buildings and Indoor Climate52074 AachenGermany

Integrating renewable energy sources is a crucial component in reducing CO_(2) emissions in the building sector. In particular, shallow geothermal energy is expected to play a significant role in the regenerative energy supply of buildings. An effective control strategy for the geothermal field is crucial to reduce the overall energy consumption. This paper analyzes the benefits of controlling an existing field’s individual borehole heat exchangers(BHE) using nonlinear model predictive control(NMPC) and moving horizon estimation. The considered geothermal field consists of 41 BHEs and is used for heating and cooling. Each BHE is equipped with temperature sensors for in-and outflow and has individually controllable valves, while a central hydraulic pump feeds all BHEs. The sensor measurements are accessed through a cloud platform, enabling also set point writing for the pump speed and the valve positions. To control the BHEs individually, we propose a two-stage process. In the calibration stage, a moving horizon estimator estimates the actual borehole and ground temperatures for each BHE. In the second stage, first, a nonlinear model predictive controller optimizes the number of active BHEs necessary to meet the buildings’ energy demand. With the estimated ground temperatures as a basis, it is determined which BHEs shall be(de)-activated. The active BHEs are fed with a fixed volume flow of 24 L/min to ensure turbulent heat transfer. To reduce the power usage of the pumps, an optimal control problem based on a simple hydraulic model of the geothermal field is used. The methodology is analyzed through simulations first and then validated experimentally. The results show that half or more of the BHEs could be deactivated most of the time, leading to 67% savings in electricity consumption by the hydraulic pump. The experimental validation confirms the high energy saving potential of the proposed methodology, reducing the consumption of electrical energy by 71%. Additiona

关键词： geothermal energy moving horizon estimation model predictive control operation optimization optimal control