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  • 1.
    Battaglioli, S.
    et al.
    Trinity College Dublin, Ireland.
    Lebon, M.
    Nexalus Labs, Ireland.
    Jenkins, R.
    Nexalus Labs, Ireland.
    Summers, Jon
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap. Luleå University of Technology, Sweden.
    Sarkinen, Jeffrey
    RISE Research Institutes of Sweden. Luleå University of Technology, Sweden.
    Robinson, A. J.
    Trinity College Dublin, Ireland.
    Enhancement of an Open Compute Project (OCP) server thermal management and waste heat recovery potential via hybrid liquid-cooling2022Ingår i: THERMINIC 2022 - 28th International Workshop on Thermal Investigations of ICs and Systems, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2022Konferensbidrag (Refereegranskat)
    Abstract [en]

    A multiphysics Simulation-Driven Design approach has been undertaken to augment the OCP Leopard Server thermal management and heat recovery hardware with the Nexalus hybrid liquid-cooled sealed server technology. Independent testing at the RISE Research Institute of Sweden has proven up to 98% heat recovery is achievable at water temperatures up to and exceeding 65°C. The improved design could maintain the elevated water temperature over a range of CPU workloads, ranging from 8% to 75%. Importantly, the design solution achieves this within an architecture that is IOU in height, half that of the original stock 20U server, potentially doubling the compute density of a rack. 

  • 2.
    Brännvall, Rickard
    et al.
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Sarkinen, Jeffrey
    RISE Research Institutes of Sweden.
    Svartholm, Joar
    RISE Research Institutes of Sweden.
    Gustafsson, Jonas
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Summers, Jon
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Digital Twin for Tuning of Server Fan Controllers2019Ingår i: 2019 IEEE 17th International Conference on Industrial Informatics (INDIN), 2019, s. 1425-1428Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cooling of IT equipment consumes a large proportion of a modern data centre’s energy budget and is therefore an important target for optimal control. This study analyses a scaled down system of six servers with cooling fans by implementing a minimal data driven time-series model in TensorFlow/Keras, a modern software package popular for deep learning. The model is inspired by the physical laws of heat exchange, but with all parameters obtained by optimisation. It is encoded as a customised Recurrent Neural Network and exposed to the time-series data via n-step Prediction Error Minimisation (PEM). The thus obtained Digital Twin of the physical system is then used directly to construct a Model Predictive Control (MPC) type regulator that executes in real time. The MPC is then compared in simulation with a self-tuning PID controller that adjust its parameters on-line by gradient descent.

  • 3.
    Brännvall, Rickard
    et al.
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap. Luleå University of Technology, Sweden.
    Siltala, Mikko
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Gustafsson, Jonas
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Sarkinen, Jeffrey
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Vesterlund, Mattias
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Summers, Jon
    EDGE: Microgrid Data Center with Mixed Energy Storage2020Ingår i: e-Energy 2020 - Proceedings of the 11th ACM International Conference on Future Energy Systems, Association for Computing Machinery, Inc , 2020, s. 466-473Konferensbidrag (Refereegranskat)
    Abstract [en]

    Low latency requirements are expected to increase with 5G telecommunications driving data and compute to EDGE data centers located in cities near to end users. This article presents a testbed for such data centers that has been built at RISE ICE Datacenter in northern Sweden in order to perform full stack experiments on load balancing, cooling, micro-grid interactions and the use of renewable energy sources. This system is described with details on both hardware components and software implementations used for data collection and control. A use case for off-grid operation is presented to demonstrate how the test lab can be used for experiments on edge data center design, control and autonomous operation. © 2020 Author.

  • 4.
    Brännvall, Rickard
    et al.
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap. Luleå University of Technology, Sweden.
    Stark, Tina
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Gustafsson, Jonas
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Eriksson, Mats
    Arctos Labs Scandinvia AB, Sweden.
    Summers, Jon
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Cost Optimization by Energy Aware Workload Placement for the Edge Cloud Continuum2022Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report investigates the problem of where to place computation workload in an edge-cloud network topology considering the trade-off between the location specific cost of computation and data communication.

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  • 5.
    Brännvall, Rickard
    et al.
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Stark, Tina
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Gustafsson, Jonas
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Eriksson, Mats
    Arctos Labs Scandinavia AB, Sweden.
    Summers, Jon
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Cost Optimization for the Edge-Cloud Continuum by Energy-Aware Workload Placement2023Ingår i: Companion Proceedings of the 14th ACM International Conference on Future Energy Systems, Association for Computing Machinery , 2023, s. 79-84Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article investigates the problem of where to place the computation workload in an edge-cloud network topology considering the trade-off between the location-specific cost of computation and data communication. For this purpose, a Monte Carlo simulation model is defined that accounts for different workload types, their distribution across time and location, as well as correlation structure. Results confirm and quantify the intuition that optimization can be achieved by distributing a part of cloud computation to make efficient use of resources in an edge data center network, with operational energy savings of 4–6% and up to 50% reduction in its claim for cloud capacity.

  • 6.
    De Boer, Gregory Nicholas
    et al.
    University of Leeds, UK.
    Johns, Adam
    University of Leeds, UK.
    Delbosc, Nicolas
    University of Leeds, UK; DS SIMULIA, Spain.
    Burdett, Daniel
    University of Leeds, UK.
    Tatchell-Evans, Morgan
    University of Leeds, UK.
    Summers, Jon
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS. University of Leeds, UK.
    Baudot, Remi
    4Energy, UK; RBCD Solutions, UK.
    Three computational methods for analysing thermal airflow distributions in the cooling of data centres2018Ingår i: International journal of numerical methods for heat & fluid flow, ISSN 0961-5539, E-ISSN 1758-6585, Vol. 28, nr 2, s. 271-288Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose – This aim of this work is to investigate different modelling approaches for air-cooled data centres. The study employs three computational methods, which are based on finite element, finite volume and lattice Boltzmann methods and which are respectively implemented via commercial Multiphysics software, opensource computational fluid dynamics code and graphical processing unit-based code developed by the authors. The results focus on comparison of the three methods, all of which include models for turbulence, when applied to two rows of datacom racks with cool air supplied via an underfloor plenum. Design/methodology/approach – This paper studies thermal airflows in a data centre by applying different numerical simulation techniques that are able to analyse the thermal airflow distribution for a simplified layout of datacom racks in the presence of a computer room air conditioner. Findings – Good quantitative agreement between the three methods is seen in terms of the inlet temperatures to the datacom equipment. The computational methods are contrasted in terms of application to thermal management of data centres. Originality/value – The work demonstrates how the different simulation techniques applied to thermal management of airflow in a data centre can provide valuable design and operational understanding. Basing the analysis on three very different computational approaches is new and would offer an informed understanding of their potential for a class of problems.

  • 7.
    Gustafsson, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Fredriksson, Sebastian
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Nilsson-Mäki, Magnus
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Olsson, Daniel
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS. RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Sarkinen, Jeffrey
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Niska, Henrik
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Seyvet, Nicolas
    OP5, Sweden.
    Minde, Tor Björn
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Summers, Jon
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    A demonstration of monitoring and measuring data centers for energy efficiency using opensource tools2018Ingår i: e-Energy 2018 - Proceedings of the 9th ACM International Conference on Future Energy Systems, 2018, s. 506-512Konferensbidrag (Refereegranskat)
    Abstract [en]

    Data centers are complex systems that require sophisticated operational management approaches to provide the availability of digital services against the backdrop of cost and energy efficiency. To achieve this, data center telemetry data is required since, as is commonly said it is not possible to manage what cannot be measured. This paper details how it is possible to construct the key data center infrastructure management (DCIM) elements of monitoring and measuring by a combination of available opensource software tools that permit both scalability and an environment where analytics can be employed on the data center operation, which can offer relevant insight into energy efficient operational practices.

  • 8.
    Jonauskaite, Domicele
    et al.
    University of Lausanne, Switzerland.
    Summers, Jon
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Mohr, Christine
    University of Lausanne, Switzerland.
    The sun is no fun without rain: Physical environments affect how we feel about yellow across 55 countries2019Ingår i: Journal of Environmental Psychology, ISSN 0272-4944, E-ISSN 1522-9610, Vol. 66, artikel-id 101350Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Across cultures, people associate colours with emotions. Here, we test the hypothesis that one driver of this cross-modal correspondence is the physical environment we live in. We focus on a prime example – the association of yellow with joy, – which conceivably arises because yellow is reminiscent of life-sustaining sunshine and pleasant weather. If so, this association should be especially strong in countries where sunny weather is a rare occurrence. We analysed yellow-joy associations of 6625 participants from 55 countries to investigate how yellow-joy associations varied geographically, climatologically, and seasonally. We assessed the distance to the equator, sunshine, precipitation, and daytime hours. Consistent with our hypotheses, participants who live further away from the equator and in rainier countries are more likely to associate yellow with joy. We did not find associations with seasonal variations. Our findings support a role for the physical environment in shaping the affective meaning of colour.

  • 9.
    Ramadhan, Abdulmajeed A.
    et al.
    University of Leeds, UK ; University of Anbar, Iraq.
    Kapur, N.
    University of Leeds, UK.
    Summers, Jon L.
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS. University of Leeds, UK.
    Thompson, H. M.
    University of Leeds, UK.
    Performance and flow characteristics of miniature EHD air blowers for thermal management applications2018Ingår i: Journal of Electrostatics, ISSN 0304-3886, E-ISSN 1873-5738, Vol. 93, s. 31-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrohydrodynamic (EHD) air blowers are receiving increasing attention as a thermal management cooling solution to overcome the restrictions of traditional rotary cooling systems used in small-scale consumer electronics. In this work, the performance and flow pattern characteristics of miniature EHD air blowers are evaluated for practical convective heat transfer applications, based on device size, operating voltage and power, and generated flow rate. For a range of blower heights up to 10 mm, two-dimensional (2D) and three-dimensional (3D) numerical models of a wire-to-plane EHD channel configuration are developed and validated against previous experimental data. Investigation of the influence of blower sidewalls, based on width parameter, on flow characteristics reveals that the 2D simulations for short and wide blower domains are valid to predict the generated flow rates effectively compared to that obtained by the means of 3D simulations. An optimized combined EHD blower is developed as a flow-controlled cooling system in thermal management applications, which minimizes the required operating voltages for specified flow rates. Comparisons against commercial rotary blowers demonstrate that the miniature EHD blowers are more competitive as cooling solutions for compact applications and extended heated surfaces based on transduction efficiency, blower size, flow production of uniform velocity profile, and power consumption.

  • 10.
    Ramadhan, Abdulmajeed
    et al.
    University of Leeds, UK ; University of Anbar, Iraq.
    Kapur, N.
    University of Leeds, UK.
    Summers, Jon
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS. University of Leeds, UK.
    Thompson, H. M.
    University of Leeds, UK.
    Numerical development of EHD cooling systems for laptop applications2018Ingår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 139, s. 144-156Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrohydrodynamic (EHD) air blowers are uniquely positioned to overcome the limitations of miniaturized mechanical fans in small-scale and consumer electronic devices. A novel cooling system design using optimized EHD blowers integrated with a plate-fin heat sink is presented and proposed for thin consumer electronics such as laptop applications. A three-dimensional (3D) numerical model is developed and validated to solve the coupled equations of EHD flow and conjugate heat transfer and predict the cooling performance of the integrated EHD system. For a range of heat sink heights from 6 to 12 mm, a parametric study is performed to investigate the influence of geometric parameters and operating conditions on the thermal performance of the EHD systems based on heat sink thermal resistance and the highest operating temperature. Numerical results demonstrate that the proposed EHD cooling system is able to provide effective cooling performance and maintain the temperature within the safe and typical operating range. Under a range of thermal design power (TDP) up to 30 W, trends of predicted operating temperatures show that the developed EHD cooling systems have great potential to compete with mechanical blowers in low-profile laptops with higher TDP, lower device height and reduced installation volume compared to a selected list of current standard laptops available commercially.

  • 11.
    Sarkinen, Jeffrey
    et al.
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Brännvall, Rickard
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Gustafsson, Jonas
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Summers, Jon
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Experimental Analysis of Server Fan Control Strategies for Improved Data Center Air-based Thermal Management*2020Ingår i: 2020 19th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm), 2020, s. 341-349Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper analyzes the prospects of a holistic air-cooling strategy that enables synchronisation of data center facility fans and server fans to minimize data center energy use. Each server is equipped with a custom circuit board which controls the fans using a proportional, integral and derivative (PID) controller running on the servers operating system to maintain constant operating temperatures, irrespective of environmental conditions or workload. Experiments are carried out in a server wind tunnel which is controlled to mimic data center environmental conditions. The wind tunnel fan, humidifier and heater are controlled via separate PID controllers to maintain a prescribed pressure drop across the server with air entering at a defined temperature and humidity. The experiments demonstrate server operating temperatures which optimally trade off power losses versus server fan power, while examining the effect on the temperature difference, ∆T. Furthermore the results are theoretically applied to a direct fresh air cooled data center to obtain holistic sweet spots for the servers, revealing that the minimum energy use is already attained by factory control. Power consumption and Power Usage Effectiveness (PUE) are also compared, confirming that decreasing the PUE can increase the overall data center power consumption. Lastly the effect of decreased server inlet temperatures is examined showing that lower inlet temperatures can reduce both energy consumption and PUE.

  • 12.
    Sjölund, Johannes
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS. RISE Research Institutes of Sweden, Digitala system, Datavetenskap. Luleå University of Technology, Sweden.
    Vesterlund, Mattias
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS.
    Nicolas, Delbosc
    Dassault Systemes Madrid, Spain.
    Khan, Amirul
    University of Leeds, UK.
    Summers, Jon
    RISE - Research Institutes of Sweden (2017-2019), ICT, SICS. University of Leeds, UK.
    Validated thermal air management simulations ofdata centers using remote graphics processing units2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Simulation tools for thermal management of datacenters help to improve layout of new builds or analyse thermalproblems in existing data centers. The development of LBMon remote GPUs as an approach for such simulations is discussedmaking use of VirtualGL and prioritised multi-threadedimplementations of an existing LBM code. The simulation isconfigured to model an existing and highly monitored test datacenter. Steady-state root mean square averages of measured andsimulated temperatures are compared showing good agreement.The full capability of this simulation approach is demonstratedwhen comparing rack temperatures against a time varyingworkload, which employs time-dependent boundary conditions.

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  • 13.
    Taddeo, Paolo
    et al.
    IREC Catalonia Institute for Energy Research, Spain.
    Romaní, Joaquim
    IREC Catalonia Institute for Energy Research, Spain.
    Summers, Jon
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Gustafsson, Jonas
    RISE Research Institutes of Sweden, Digitala system, Datavetenskap.
    Martorell, Ingrid
    Universitat de Lleida, Spain.
    Salom, Jaume
    IREC Catalonia Institute for Energy Research, Spain.
    Experimental and numerical analysis of the thermal behaviour of a single-phase immersion-cooled data centre2023Ingår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 234, artikel-id 121260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Server power densities are foreseen to increase, and conventional air-cooling systems will struggle to cope with thermal demand. Single-phase immersion systems are a promising alternative to operate very intensive workload such as high-performance computing, cryptocurrencies mining or research activities. However, few companies deal with this kind of system and there is a lack of energy models that can reproduce an accurate analysis of the system behaviour. This study addresses the experimentation, data collection, and model validation of a single-phase immersion cooling system where 54 open compute project servers, each with a peak power of 400 Watts that are submerged and operated in a dielectric coolant. Results show the evolution of the thermal profile of the system under static and dynamic workloads, and it provides a correlation of server energy use under various system temperatures. The energy model is presented, validated against real data, and exploited to investigate the system response to different cooling conditions. In conclusion, the study demonstrates the validation of the energy model and supports the basis for further investigation. © 2023 The Authors

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