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A Reinforcement Learning approach for the continuous electricity market ofGermany: Trading from the perspective of a wind park operator

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Energy and AI 2022年第2期8卷 67-78页

作者： Malte Lehna Björn Hoppmann Christoph Scholz renéheinrich Fraunhofer Institute for Energy Economics and Energy System Technology(IEE) Königstor 5934119 KasselGermany

With the rising extension of renewable energies, the intraday electricity markets have recorded a growingpopularity amongst traders as well as electric utilities to cope with the induced volatility of the energysupply. Through their short trading horizon and continuous nature, the intraday markets offer the abilityto adjust trading decisions from the day-ahead market or reduce trading risk in a short-term notice. Producersof renewable energies utilize the intraday market to lower their forecast risk, by modifying their providedcapacities based on current forecasts. However, the market dynamics are complex due to the fact that thepower grids have to remain stable and electricity is only partly storable. Consequently, robust and intelligenttrading strategies are required that are capable to operate in the intraday market. In this work, we proposea novel autonomous trading approach based on Deep Reinforcement Learning (DRL) algorithms as a possiblesolution. For this purpose, we model the intraday trade as a Markov Decision Process (MDP) and employ theProximal Policy Optimization (PPO) algorithm as our DRL approach. A simulation framework is introducedthat enables the trading of the continuous intraday price in a resolution of one minute steps. We test ourframework in a case study from the perspective of a wind park operator. We include next to general tradeinformation both price and wind forecasts. On a test scenario of German intraday trading results from 2018,we are able to outperform multiple baselines with at least 45.24% improvement, showing the advantage of theDRL algorithm. However, we also discuss limitations and enhancements of the DRL agent, in order to increasethe performance in future works.

关键词： Deep Reinforcement Learning German intraday electricity trading Deep neural networks Markov Decision Process Proximal Policy Optimization Electricity price forecast

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Surfel-based surface modeling for robotic belt grinding simulation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第7期7卷 1215-1224页

作者： ren Xiang-yang MUELLER heinrich KUHLENKOETTER Bernd Robotics Research Institute University of Dortmund Dortmund 44227 Germany Informatik VII University of Dortmund Dortmund 44227 Germany

The new flee-form surface modelling technology for robotic belt grinding simulation presented in this paper is based on discrete surfel elements generated from the surface approximation point set and can facilitate the simulation implementation. A local process model exploits the advantage of surfel representation to compute the material removal rate and the final surface grinding error can be easily carried out. With the help of this system, robot programmers can improve the path planning and predict potential problems by visualizing the manufacturing process.

关键词： Surface modelling Surfel Belt-grinding simulation

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MP-PIC simulation of circulating fluidized beds using an EMMS based drag model for Geldart B particles

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Particuology 2021年第6期19卷 76-90页

作者： Timo Dymala Tom Wytrwat Stefan heinrich Hamburg University of Technology Institute of Solids Process Engineering and Particle TechnologyDenickestr.1521073 HamburgGermany

In this study the multiphase particle-in-cell(MP-PIC)method is used for the simulation of two pilot-scale circulating fluidized beds(CFBs)with quartz sand belonging to Geldart’s group B as bed *** simulations were performed using a homogeneous drag model as well as a structure dependent drag model based on the energy minimization multi-scale method(EMMS).The results are compared with experimental data from literature as well as *** simulations with the EMMS based drag model show a good agreement of the time-averaged axial solids concentration,circulation rate and riser pressure ***,a lower grid sensitivity is observed compared to the homogeneous drag *** contrast to the conventional drag model a dense bottom zone is predicted by the EMMS based drag *** overprediction of the solid concentration in the dense bottom zone is presumably due to an overprediction of the cluster diameter that is calculated using an empirical cluster diameter *** shows the necessity for a new meso-scale cluster correlation for the simulation of Geldart B ***,the results of the time-averaged radial solids concentration differ from the expectations of a core-annulus flow indicating that a mesh refinement at the walls is ***,the importance of using a realistic particle size distribution is identified.

关键词： 3D-CFD simulation Circulating fluidized bed(CFB) Multiphase particle-in-cell method(MP-PIC) Energy minimizing multi-scale theory(EMMS) Validation study

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Pathological tumor response to neoadjuvant therapy in borderline resectable pancreatic cancer

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Hepatobiliary & Pancreatic Diseases International 2019年第4期18卷 305-306页

作者： Stefan heinrich General Visceral and Transplantation Surgery University Hospital of Mainz

Surgery is the standard therapy for pancreatic ductal adenocarcinoma(PDAC).After the dramatic decline of operative mortality over the past decades,the indications for pancreas resections have been continuously extended:currently resections of the portal/superior mesenteric vein are considered standard by many centers,and even arterial resections are under *** these changes,different expert groups have defined resectability criteria containing a grey zone(“borderline resectable disease”)of tumors,which may be technically resectable with appropriate surgical expertise,but resection inherits an increased risk of an R1-resection[1].

关键词： Surgery mortality operative

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Why surgeons care about systemic chemotherapy for pancreatic cancer?

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Hepatobiliary Surgery and Nutrition 2021年第6期10卷 860-863页

作者： Stefan heinrich Department of General Visceral and Transplantation SurgeryUniversity Hospital of MainzMainzGermany

Pancreatic adenocarcinoma(PDAC)has become the seventh most frequent cause of cancer death in the world with increasing incidence independent of patient sex and age with smoking and alcohol consumption being the most important risk factors(1).The high mortality rate is mainly attributed to the biological characteristics of this disease:even small tumors reveal perineural invasion or local spread into lymph and blood vessels resulting in systemic *** estimated risk of occult distant metastasis at the time of surgery is 28%and 94%for tumors with a diameter of 1 and 3 cm,respectively(2).Consequently,many patients present with disseminated or locally advanced disease and are at high risk for early tumor recurrence(3).

关键词： cancer invasion mortality

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The current role of liver surgery in the treatment of colorectal liver metastases

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Hepatobiliary Surgery and Nutrition 2019年第5期8卷 552-554页

作者： Stefan heinrich General Visceral and Transplantation SurgeryUniversity Hospital of MainzMainzGermany

Since the establishment of a survival benefit for patientswith colorectal cancer liver metastases(CRLM)undergoingliver resection,perioperative outcome has continuouslyimproved,and surgery for CRLM is currently offered... 详细信息

关键词： colorectal surgery metastases

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Neoadjuvant therapy for pancreatic ductal adenocarcinoma—real effects or patient selection?

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Hepatobiliary Surgery and Nutrition 2018年第4期7卷 289-291页

作者： Stefan heinrich Department of General Visceral and Transplantation Surgery University Hospital of Mainz Mainz Germany

Surgery is the only treatment with curative potential for patients with pancreatic ductal adenocarcinoma (PDAC).Unfortunately, the majority of patients do not qualify for curative resection due to locally advanced or ... 详细信息

关键词： adenocarcinoma Surgery curative

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Variability of European beech wood density as influenced by interactions between treering growth and aspect

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Forest Ecosystems 2016年第3期3卷 165-173页

作者： Daniela Diaconu Marc Wassenberg heinrich Spiecker Chair of Forest Growth and Dendroecology Albert-Ludwigs-University

Background： Wood density is considered to be the most important predictor of wood quality but despite its importance, diffuse-porous tree species have been the subject of only a limited number of studies. The importance of European beech forests for Central Europe calls for profound research to examine the potential impact of a warmer climate on the quality of beech timber. Methods： In this study we analysed the influence of tree-ring width and tree-ring age on the wood density of beech, and whether the wood density response to these two parameters is modified by aspect. A linear mixed-effects model for wood density was constructed for mean density data measured with high frequency densitometry on stem discs from 72 beech trees sampled from two different aspects （northeast -NE and southwest -SW） of a valley in southwestern Germany. Results： Part of the variability of mean annual wood density was explained by cambial age： an increase in cambial age resulted in an increase in mean wood density. Tree-ring width and aspect had only a small influence on wood density, Wood density on the SW aspect was lower than on the NE with a difference of approximately 0.006 g/cm3. The between-tree variability was very high. Conclusions： The significant interaction between cambial age and aspect reflects the importance of site conditions at older tree ages： with increasing cambial age the difference between aspects becomes stronger. Our results give a better understanding of the importance of site conditions on the wood quality of beech.

关键词： Fagus sylvatica HF densitometry Wood quality Wood density Aspect

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Influence of liquid layers on energy absorption during particle impact

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Particuology 2009年第4期7卷 245-259页

作者： Sergiy Antonyuk Stefan heinrich Niels Deen Hans Kuipers Hamburg University of Technology Institute of Solids Process Engineering and Particle Technology Denickestr. 15 21071 Hamburg Germany University of Twente Fundamentals of Chemical Reaction Engineering Faculty of Science and Technology PO Box 217 Enschede 7500 AE The Netherlands

The influence of the thickness of a covering liquid layer and its viscosity as well as the impact velocity on energy loss during the normal impact on a flat steel wall of spherical granules with a liquid layer was studied. Free-fall experiments were performed to obtain the restitution coefficient of elastic-plastic γ- Al2O3 granules by impact on the liquid layer, using aqueous solutions of hydroxypropyl methylcellulose with different concentrations for variation of viscosity （1-300 mPa s）, In the presence of a liquid layer, increase of liquid viscosity decreases the restitution coefficient and the minimum thickness of the liquid layer at which the granule sticks to the wall. The measured restitution coefficients were compared with experiments performed without liquid layer. In contrast to the dry restitution coefficient, due to viscous losses at lower impact velocity, higher energy dissipation was obtained, A rational explanation for the effects obtained was given by results of numerically solved force and energy balances for a granule impact on a liquid layer on the wall. The model takes into account forces acting on the granule including viscous, surface tension, capillary, contact, drag, buoyancy and gravitational forces. Good agreement between simulations and experiments has been achieved.

关键词： Granule impact Restitution coefficient Energy dissipation Liquid layer Liquid bridge

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Evaluation of Turbulence Models in Predicting Hypersonic and Subsonic Base Flows Using Grid Adaptation Techniques

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Chinese Journal of Aeronautics 2012年第3期25卷 325-334页

作者： YOU Yancheng BUANGA Bjorn HANNEMANN Volker LUDEKE heinrich Institute of Aerodynamics and Flow Technology German Aerospace Center (DLR) Braunschweig 38108 Germam Institute of Aerodynamics and Flow Technology German Aerospace Center (DLR) Gottingen 37073 Germany Department of Aeronautics Xiamen University Xiamen 361005 China

The flows behind the base of a generic rocket, at both hypersonic and subsonic flow conditions, are numerically studied. The main concerns are addressed to the evaluation of turbulence models and the using of grid adaptation techniques. The investigation focuses on two configurations, related to hypersonic and subsonic experiments. The applicability tests of different turbu- lence models are conducted on the level of two-equation models calculating the steady state solution of the Reynolds-averaged Navier-Stokes（RANS） equations. All used models, the original Wilcox k-co, the Menter shear-stress transport （SST） and the ex- plicit algebraic Reynolds stress model（EARSM） formulation, predict an asymmetric base flow in both cases caused by the support of the models. A comparison with preliminary experimental results indicates a preference for the SST and EARSM results over the results from the older k-co model. Sensitivity studies show no significant influence of the grid topology or the location of the laminar to turbulent transition on the base flow field, but a strong influence of even small angles of attack is reported from the related experiments.

关键词： base flows turbulence models steady calculation grid adaptation numerical simulation

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