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    NachhaltigF: Elektrotechnik und Medientechnik

    Zeitschriftenartikel

    Christoph Metzke, Fabian Kühnel, Jonas Weber, Günther Benstetter

    Scanning Thermal Microscopy of Ultrathin Films: Numerical Studies Regarding Cantilever Displacement, Thermal Contact Areas, Heat Fluxes, and Heat Distribution

    Nanomaterials, vol. 11, no. 2

    2021

    DOI: 10.3390/nano11020491

    Abstract anzeigen

    New micro- and nanoscale devices require electrically isolating materials with specific thermal properties. One option to characterize these thermal properties is the atomic force microscopy (AFM)-based scanning thermal microscopy (SThM) technique. It enables qualitative mapping of local thermal conductivities of ultrathin films. To fully understand and correctly interpret the results of practical SThM measurements, it is essential to have detailed knowledge about the heat transfer process between the probe and the sample. However, little can be found in the literature so far. Therefore, this work focuses on theoretical SThM studies of ultrathin films with anisotropic thermal properties such as hexagonal boron nitride (h-BN) and compares the results with a bulk silicon (Si) sample. Energy fluxes from the probe to the sample between 0.6 µW and 126.8 µW are found for different cases with a tip radius of approximately 300 nm. A present thermal interface resistance (TIR) between bulk Si and ultrathin h-BN on top can fully suppress a further heat penetration. The time until heat propagation within the sample is stationary is found to be below 1 µs, which may justify higher tip velocities in practical SThM investigations of up to 20 µms−1. It is also demonstrated that there is almost no influence of convection and radiation, whereas a possible TIR between probe and sample must be considered.

    NachhaltigF: Maschinenbau und Mechatronik

    Zeitschriftenartikel

    T. Mull, T. Wagner, Giuseppe Bonfigli, S. Buchholz, Frank Schäfer, E. Schleicher, C. Schuster, M. Sporn

    Safety cases for design-basis accidents in LWRs featuring passive systems

    [In Press]

    Nuclear Engineering and Design, no. Available online 26 February 2021

    2021

    DOI: 10.1016/j.nucengdes.2021.111095

    Abstract anzeigen

    This paper presents results from a series of integral tests performed at Framatome’s INKA test facility in Karlstein (Germany) which simulates a KERENA boiling water reactor (BWR). The scope of the test series was on the behaviour of and interaction between the different passive systems and components under the conditions of extended loss of alternating power (ELAP). These SBO-like conditions were aggravated in three out of four tests by parallel LOCA (Loss of Coolant Accident). The scenarios of all four tests fully correspond to Design Basic Conditions (DBC). They were: main steam line break, feed water line break, reactor pressure vessel (RPV) bottom leak and station blackout (SBO, non-LOCA). In the tests, the passive systems integrated in KERENA and INKA, respectively, have fulfilled their design functions fully satisfactorily and as follows: The Passive Pressure Pulse Transmitter (PPPT) triggered the RPV depressurization without delay. The Emergency Condenser (EC) system removed decay heat along with stored energy from the RPV to the containment. The Containment Cooling Condenser (CCC) system forwarded said power to a heat sink outside of the containment. The passive containment pressure suppression system kept the containment pressure within the design range, partially displacing surplus thermal energy from the drywell to the wetwell, in particular in the early phases after occurrence of LOCA. The passive core flooding system replenished the coolant inventory of the RPV thereby ensuring water levels in the RPV which are fully sufficient for core cooling. Moreover, the systems have cooperated as anticipated by the designers, quietly and without perturbing each other. Hence the test results, which are reported and discussed more in detail within this paper, soundly confirm the underlying design and its passive features. Said tests were carried out as a part of the joint research project EASY (Evidence of Design Basis Accidents Mitigation solely with passive safety Systems), the overarching objective of which was the development and validation of the code system AC2 of GRS (Gesellschaft für Anlagen- und Reaktorsicherheit gGmbH).

    DigitalNachhaltigF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    M. Metzger, M. Duckheim, M. Franken, H. Heger, Matthias Huber, M. Knittel, T. Kolster, M. Kueppers, C. Meier, D. Most, S. Paulus, L. Wyrwoll, A. Moser, S. Niessen

    Pathways toward a Decarbonized Future—Impact on Security of Supply and System Stability in a Sustainable German Energy System

    Energies, vol. 14, no. 3

    2021

    DOI: 10.3390/en14030560

    Abstract anzeigen

    Pathways leading to a carbon neutral future for the German energy system have to deal with the expected phase-out of coal-fired power generation, in addition to the shutdown of nuclear power plants and the rapid ramp-up of photovoltaics and wind power generation. An analysis of the expected impact on electricity market, security of supply, and system stability must consider the European context because of the strong coupling—both from an economic and a system operation point of view—through the cross-border power exchange of Germany with its neighbors. This analysis, complemented by options to improve the existing development plans, is the purpose of this paper. We propose a multilevel energy system modeling, including electricity market, network congestion management, and system stability, to identify challenges for the years 2023 and 2035. Out of the results, we would like to highlight the positive role of innovative combined heat and power (CHP) solutions securing power and heat supply, the importance of a network congestion management utilizing flexibility from sector coupling, and the essential network extension plans. Network congestion and reduced security margins will become the new normal. We conclude that future energy systems require expanded flexibilities in combination with forward planning of operation.

    NachhaltigF: Maschinenbau und Mechatronik

    Zeitschriftenartikel

    Giuseppe Bonfigli, S. Buchholz, F. Schäfer, Nadine Kaczmarkiewicz, C. Schuster, M. Sporn

    Safety cases for design-basis accidents in LWRs featuring passive systems Part 2 – Numerical investigations

    Nuclear Engineering and Design, vol. 372, no. February

    2021

    DOI: 10.1016/j.nucengdes.2020.110996

    Abstract anzeigen

    This paper deals with the improvement and validation of numerical tools for the simulation of design basis accidents in nuclear power plants equipped with passive safety systems. Numerical models are implemented in the framework of the 1-D thermal–hydraulic system code ATHLET developed by GRS. Experimental reference data for the validation were obtained at the INKA test facility, a model of the KERENA reactor, reproducing the passive safety systems nearly at full scale. The validation effort focuses firstly on the accuracy of the models for the single passive components, and secondly on the ability of the numerical simulation to reproduce the interaction of all components of the KERENA design under realistic conditions as reproduced in the INKA test facility. Thermal-hydraulic models are presented and validated for two passive components of the KERENA reactor: the passive pressure pulse transmitter and the pressure-controlled flooding valve. Finally, the full model of the INKA facility, including these and other passive components, is discussed and numerical results for simulations reproducing three different design basis accidents are validated by comparison with the corresponding experimental data.

    DigitalNachhaltigF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    Kueppers. M., S. Paredes Pineda, M. Metzger, Matthias Huber, S. Paulus, H. Heger, S. Niessen

    Decarbonization pathways of worldwide energy systems – Definition and modeling of archetypes

    Applied Energy, vol. 285, no. 01 March 2021

    2021

    DOI: 10.1016/j.apenergy.2021.116438

    Abstract anzeigen

    Energy system models help to find the optimal technology mixes for decarbonization strategies in countries worldwide. To reduce the modeling effort and analyze as many countries as possible, this paper proposes a novel approach of energy system archetypes which can be directly evaluated. These archetypes classify similar countries worldwide independently from their geographic location. Advantages of this idea are the setup of a transferable global database allowing for data reconstruction between countries, market size estimations, and the ability to compare peer countries facing similar challenges. To enable such modeling, a framework is developed in which the archetypes are defined, standardized modeling rules are developed, and the results are evaluated for validation. In a benchmark against simple geographic classifications, the presented clustering approach, which results in 15 archetypes, improves the variance between all countries and their corresponding archetypes by 44% compared to the variance between the countries and their geographic sub-regions. The model results of these archetypes state the need of balancing technologies for the daily cycle of photovoltaic generation and the general importance of flexibility in future decarbonized energy systems. Overall, the results confirm that archetypes are an adequate approach to derive the set of solutions for the decarbonization of worldwide countries.

    NachhaltigF: Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    A. Hamid, J. Sun, H. Zhang, Thomas Stirner

    Molecular dynamics simulation analysis of helium cluster growth conditions under tungsten surfaces

    Computational Materials Science, vol. 186, no. January

    2021

    DOI: 10.1016/j.commatsci.2020.109994

    Abstract anzeigen

    Molecular dynamics simulations have been performed to study the effects of helium fluxes on helium cluster size underneath tungsten surfaces under bombardment of helium atoms with incident energy 30 100 eV at temperature 300 2100 K. The simulation results show that the helium cluster size depends on the magnitude of the helium flux: at a higher flux, the helium clusters on average form in smaller size in tungsten but with larger number; while the clusters form further away from the surface at a lower flux. The coalescence of He atoms and helium bubbles depends on the tungsten temperature: at elevated temperatures around 2000 K, the incident He atoms in tungsten slow down more rapidly than at 1000 K but the number of vacancies per He cluster is smaller. The incident energy has a strong effect on the retention of helium atoms: The helium retention rate increases with the incident energy, and the helium retention depends weakly on temperature in the low energy range of interest. It is also found that the surface orientation plays an important role not only in determining the depth distribution but also in determining the helium retention and cluster size: at the surface {1 1 0}, the retention rate of helium atoms is the lowest, and at the surface {1 1 1}, the clusters grow easily in the lateral direction. The present simulation results suggest that the {0 0 1} surface is favorable for fuzz growth. The results obtained in the present work provide insight to the reasons why the fuzz only grows within a certain parameter range at the atomic level.

    DigitalF: Angewandte InformatikS: TC Freyung

    Zeitschriftenartikel

    J. Trager, L. Kalová, Raphaela Pagany, Wolfgang Dorner

    Warning apps for road safety – a technological and economical perspective for autonomous driving

    [Article submitted]

    International Journal of Human–Computer Interaction

    2021

    DigitalF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    Mouzhi Ge, W. Lewoniewski

    Developing the Quality Model for Collaborative Open Data

    Procedia Computer Science, vol. 176, pp. 1883-1892

    2020

    DOI: 10.1016/j.procs.2020.09.228

    Abstract anzeigen

    Nowadays, the development of data sharing technologies allows to involve more people to collaboratively contribute knowledge on the Web. The shared knowledge is usually represented as Collaborative Open Data (COD), for example, Wikipedia is one of the well-known sources for COD. The Wikipedia articles can be written in different languages, updated in real time, and originated from a vast variety of editors. However, COD also bring different data quality problems such as data inconsistency and low data objectiveness due to the crowd-based and dynamic nature. These data quality problems such as biased information may lead to sentimental changes or social impacts. This paper therefore proposes a new measurement model to assess the quality of COD. In order to evaluate the proposed model, A preliminary experiment is conducted with a large scale of Wikipedia articles to validate the applicability and efficiency of this proposed quality model in the real-world scenario.

    DigitalF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    B. Mbarek, Mouzhi Ge, T. Pitner

    An Efficient Mutual Authentication Scheme for Internet of Things

    Internet of Things, vol. 9, no. 1

    2020

    DOI: 10.1016/j.iot.2020.100160

    Abstract anzeigen

    The Internet of Things (IoT) is developed to facilitate the connections and data sharing among people, devices, and systems. Among the infrastructural IoT techniques, Radio Frequency IDentification (RFID) has been used to enable the proliferation and communication in IoT networks. However, the RFID techniques usually suffer from security issues due to the inherent weaknesses of underlying wireless radio communications. One of the main security issues is the authentication vulnerability from the jamming attack. In order to tackle the vulnerabilities of key updating algorithms, this paper therefore proposes an efficient authentication scheme based on the self-adaptive and mutual key updating. Furthermore, we evaluate the performance and applicability of our solution with a thorough simulation by taking into account the energy consumption, authentication failure rate and authentication delay. The feasibility and applicability are demonstrated by implementing the proposed authentication scheme in smart home IoT systems.

    DigitalF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    M. Macak, Mouzhi Ge, B. Buhnova

    A Cross-Domain Comparative Study of Big Data Architectures

    International Journal of Cooperative Information Systems, vol. 29, no. 04

    2020

    DOI: 10.1142/S0218843020300016

    Abstract anzeigen

    Nowadays, a variety of Big Data architectures are emerging to organize the Big Data life cycle. While some of these architectures are proposed for general usage, many of them are proposed in a specific application domain such as smart cities, transportation, healthcare, and agriculture. There is, however, a lack of understanding of how and why Big Data architectures vary in different domains and how the Big Data architecture strategy in one domain may possibly advance other domains. Therefore, this paper surveys and compares the Big Data architectures in different application domains. It also chooses a representative architecture of each researched application domain to indicate which Big Data architecture from a given domain the researchers and practitioners may possibly start from. Next, a pairwise cross-domain comparison among the Big Data architectures is presented to outline the similarities and differences between the domain-specific architectures. Finally, the paper provides a set of practical guidelines for Big Data researchers and practitioners to build and improve Big Data architectures based on the knowledge gathered in this study.

    DigitalF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    F. Persia, G. Pilato, Mouzhi Ge, P. Bolzoni, D. D’Auria, S. Helmer

    Improving orienteering-based tourist trip planning with social sensing

    Future Generation Computer Systems, vol. 110, no. 9, pp. 931-945

    2020

    DOI: 10.1016/j.future.2019.10.028

    Abstract anzeigen

    We enhance a tourist trip planning framework based on orienteering with category constraints by adding social sensing. This allows us to customize a user’s experience without putting the burden of preference elicitation on the user. We identify the interests of a user by analyzing their Tweets and then match these interests to descriptions of points of interests. For this analysis we adapt different schemes for social sensing to the needs of our orienteering context and compare them to find the most suitable approach. We show that our technique is fast enough for use in real-time dynamic settings and also has a higher accuracy compared to previous approaches. Additionally, we integrate a more efficient algorithm for solving the orienteering problem, boosting the overall performance and utility of our framework further, as demonstrated by the positive user satisfaction received by real users.

    DigitalF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    M. Drăgoicea, L. Walletzký, L. Carrubbo, Nabil Badr, Angeliki T., F. Romanovská, Mouzhi Ge

    Service Design for Resilience: A Multi-Contextual Modeling Perspective

    IEEE Access, vol. 8, pp. 185526-185543

    2020

    DOI: 10.1109/ACCESS.2020.3029320

    Abstract anzeigen

    This paper introduces a conceptual framework aiming to broaden the discussion on resilience for the design of public services. From a theoretical point of view, the paper explores service design with a Systems Thinking lens. A multi-contextual perspective aiming to analyze, decompose, and design smart cities services where resilience is an input at the service design level is described and the four diamondsof-context model for service design (4DocMod) is introduced. This service model accommodates various actors' contexts in public service design and consists of four design artefacts, the diamonds (See, Recognize, Organize, Do). From a practical point of view, guidelines for the application of the 4DocMod service model extension for resilience are described along with two case studies addressing the recent COVID-19 pandemic that illustrates a clear situation of resilience with insights in multiple contexts. According to the findings of this paper, it is obvious that resilience is not “just”a request. Instead, it plays a higher role within the service system. It is not “just”another Context, either. Instead, it goes through many contexts with different circumstances. In this manner, it is possible to address the qualities through which actors can become resilient, at the service design stage, to ensure continuity of the public services in times of emergency. As our approach using the 4DocMod is proposing, resilience may be is achieved when specific properties are provisioned at information service design level.

    DigitalGesundF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    R. Istepanian, M. Kulhandjian, Georgi Chaltikyan

    Mobile Health (mHealth) in the Developing World: Two Decades of Progress or Retrogression

    Journal of the International Society for Telemedicine and eHealth (JISfTeH), vol. 8, no. e24, pp. 1-5

    2020

    DOI: 10.29086/JISfTeH.8.e24

    Abstract anzeigen

    Mobile healthcare, or mHealth, is one of the key pillars of information and communication technologies for healthcare that consists of telemedicine, telehealth, eHealth, and mHealth. In the past two decades, mobile health has become a transformative concept for healthcare delivery innovations on a global scale. The success was based on the market-driven strategies that utilised the advances in mobile communications, computing, and sensor technologies, especially in recent years. Those market-driven mobile health systems were also closely associated with the global proliferation of smartphones, and based on the correlated usage principle of the smartphone applications for healthcare and wellbeing. However, the global commercial success of the smartphone-based mHealth model was not widely translated into successful scaled-up and tangible healthcare benefits, especially in low- and-middle income countries, compared to the consumer mobile health markets. The numerous healthcare challenges in the developing world remained largely untackled by the existing mobile health systems and models. The much-hyped transformative benefits of these systems remain largely unfulfilled. For two decades since the inception of this concept, the majority of the population in resource-limited healthcare settings still remain in poorer health and live in worsened conditions, with limited if any access to basic healthcare services. The much-hyped mobile health services that promised transforming these fragile and limited healthcare conditions, did not come to wider fruition globally. The COVID-19 pandemic, with its devastating human and economic impact worsened this status. An overview of the origin and the basic principles of mobile health, its current landscape and status in the developing world is presented. The impact of the smartphone-centric model that dominated the landscape of mobile health systems in these countries is discussed, and a critical view on the limitation of this mobile health model adopted widely in these settings is provided.

    DigitalGesundF: Europan Campus Rottal-Inn

    Zeitschriftenartikel

    Fara Fernandes, Georgi Chaltikyan

    Analysis of Legal and Regulatory Frameworks in Digital Health: A Comparison of Guidelines and Approaches in the European Union and United States

    Journal of the International Society for Telemedicine and eHealth (JISfTeH), vol. 8, no. e11, pp. 1-13

    2020

    DOI: 10.29086/JISfTeH.8.e11

    Abstract anzeigen

    The advent of digital technology in healthcare presents opportunities for the improvement of healthcare systems around the world and the move towards value-based treatment. However, this move must be accompanied by strong legal and regulatory frameworks that will not only facilitate but encourage the good use of technology. The goal of the study was to assess the amenability and furtherance of regulatory frameworks in digital health by evaluating and comparing the processes, effectiveness and outcomes of these frameworks in the European Union and United States. Methods: This study incorporated two research methodologies. The first was a research of current legal and regulatory frameworks in digital health in the European Union and United States. A comprehensive online search for publications was carried out which included laws, regulations, policies, green papers, guidelines and recommendations. This research was complemented with interviews of five purposively sampled key informants in the legal and regulatory landscape. Results: Mind-maps revealed key features and challenges of the digital health field in the topics of the current state of regulation of digital health in the EU, Germany and US, regulatory pathways for digital health devices, protection and privacy of health data, mobile health validation, risk-based classification of medical devices, regulation of clinical decision support systems, telemedicine, artificial intelligence and emerging technologies, reimbursement for digital health services and liability for digital health products. The experts expressed and explained key points where current regulation is deficient. The review of the legal frameworks revealed deficiencies which provide opportunities and recommendations to further develop and strengthen the regulatory landscape. Conclusions: A key element to a robust regulatory framework is the ability to ensure trust and confidence in using digital health technology. Technology must measure the impact on quality of life and burden of disease and not merely involve the collection of data.

    DigitalF: Angewandte Wirtschaftswissenschaften

    Zeitschriftenartikel

    Christian Mandl

    Datengetriebene Planungsmethoden zur Steuerung der Rohstoffbeschaffung und des physischen Rohstoffhandels unter Preisrisiko

    OR News (Das Magazin der Gesellschaft für Operations Research e.V.), vol. 70, no. November

    2020

    DigitalF: Angewandte Wirtschaftswissenschaften

    Zeitschriftenartikel

    Christian Mandl, S. Minner

    Data-Driven Optimization for Commodity Procurement Under Price Uncertainty

    Manufacturing and Service Operations Management, no. Published Online:18 Aug 2020

    2020

    DOI: 10.1287/msom.2020.0890

    Abstract anzeigen

    Problem definition: We study a practice-motivated multiperiod stochastic commodity procurement problem under price uncertainty with forward and spot purchase options. Existing approaches are based on parametric price models, which inevitably involve price model misspecification and generalization error. Academic/practical relevance: We propose a nonparametric, data-driven approach (DDA) that is consistent with the optimal procurement policy structure but without requiring the a priori specification and estimation of stochastic price processes. In addition to historical prices, DDA is able to leverage real-time feature data, such as economic indicators, in solving the problem. Methodology: This paper provides a framework for prescriptive analytics in dynamic commodity procurement, with optimal purchase policies learned directly from data as functions of features, via mixed integer linear programming (MILP) under cost minimization objectives. Hence, DDA focuses on optimal decisions rather than optimal predictions. Furthermore, we combine optimization with regularization from machine learning (ML) to extract decision-relevant data from noise. Results: Based on numerical experiments and empirical data, we show that there is a significant value of feature data for commodity procurement when procurement policy parameters are learned as functions of features. However, overfitting deteriorates the performance of data-driven solutions, which asks for ML extensions to improve out-of-sample generalization. Compared with an internal best-practice benchmark, DDA generates savings of on average 9.1 million euros per annum (4.33%) for 10 years of backtesting. Managerial implications: A practical benefit of DDA is that it yields simple but optimally structured decision rules that are easy to interpret and easy to operationalize. Furthermore, DDA is generalizable and applicable to many other procurement settings.

    F: Angewandte WirtschaftswissenschaftenI: Institut GMRC

    Zeitschriftenartikel

    Josef Scherer

    Risikomanagement – Ein Plädoyer – Unverzichtbares Instrument in der Krise

    TRIOLOG - Das Transfermagazin für Wissenschaft, Wirtschaft und Gesellschaft in Ostbayern, vol. 2, no. 4, pp. 32-33

    2020

    Abstract anzeigen

    Die Corona-Krise und ihre wirtschaftlichen Folgen setzen vielen Branchen und Unternehmen in Deutschland wie auch auf der ganzen Welt hart zu. Trotz aller Gefahren und Probleme, mit denen die Unternehmer derzeit konfrontiert sind, sieht der Jurist Prof. Dr. Josef Scherer auch Chancen in der Krise. Der Professor an der Technischen Hochschule Deggendorf (THD) wirbt eindringlich für ein gut aufgebautes und aktiv gelebtes Risikomanagement in den Unternehmen. Dies sei eine grundsätzliche Voraussetzung, um Krisen gut zu meistern. Gleichzeitig schaffe gelebtes Risikomanagement laut Scherer nachhaltige Werte, die wiederum die Widerstandsfähigkeit der Unternehmen in Krisen erhöhen.

    DigitalNachhaltigF: Angewandte WirtschaftswissenschaftenI: Institut GMRC

    Zeitschriftenartikel

    Josef Scherer

    Resilienz & Zukunftsfähigkeit: Aktuelle Anforderungen an Unternehmensführung (GRC), Digitalisierung und Nachhaltigkeit

    JMG Journal für Medizin- und Gesundheitsrecht, no. 3, pp. 165-172

    2020

    DigitalGesundF: Angewandte WirtschaftswissenschaftenI: Institut GMRC

    Zeitschriftenartikel

    Josef Scherer, Ann-Kathrin Birker

    „Unternehmensführung 4.0“ in der Health-Care- und Pflege-Branche: Der „Ordentliche Kaufmann 4.0“ und sein digitalisiertes Integriertes GRC-Managementsystem:„Das Richtige richtig tun“ in unsicheren Zeiten!

    JMG Journal für Medizin- und Gesundheitsrecht, no. 1, pp. 34-47

    2020

    NachhaltigF: Elektrotechnik und Medientechnik

    Zeitschriftenartikel

    C. Niu, Y. Zhang, Y. Cui, X. Li, W. Liu, W. Ni, H. Fan, N. Lu, Günther Benstetter, G. Lei, D. Liu

    Effect of temperature on the growth and surface bursting of He nano-bubbles in W under fusion-relevant He ion irradiations

    Fusion Engineering and Design, vol. 163, no. Available online 26 December 2020

    2020

    DOI: 10.1016/j.fusengdes.2020.112159

    Abstract anzeigen

    Under fusion-relevant He+ irradiations, the W surface temperature is one of the most important parameters for controlling the fuzz growth over the W divertor targets, which is associated with the surface bursting of He nano-bubbles. Using He reaction rate model in W, we investigate the effect of temperature on the growth and surface bursting of He nano-bubbles under low-energy (100 eV) and large-flux (∼1022/m2⋅s) He+ irradiations. Increasing the irradiation temperature from 750 to 2500 K leads to a significant change in both the radius of He nano-bubbles and He retention. At an elevated temperature, He solute atoms prefer to rapidly diffuse into He nano-bubbles, thus affecting their concentration, growth and surface bursting. The decrease in He retention is attributed to an increase in the hop rate of solute He atoms in the W top layer, resulting in the significant He release from the W surface. The radius and density of He nano-bubbles calculated by our model are consistent with our experimental observation.