UK & CHN Core - UK & China Centre for Offshore Renewable Energy
  • ResIn

Resilient Integrated-Coupled FOW platform design methodology (ResIn) – EP/R007519/1

Led by: Professor Lars Johanning, University of Exeter, and Professor Bing Chen, Dalian University of Technology, EPSRC funding: £811,976

The vision of this multi-disciplinary project is to provide a foundation to develop and demonstrate an integrated approach to system resilience for ORE in China and the UK, improving energy security while reducing environmental impacts.

The proposal builds on environmental resource assessment techniques and data that enable enhanced characterisation methodologies with a focus towards localised environmental conditions and extremes. The engineering focus lies on the quantification and validation of the load reduction potential of novel floating offshore wind platform innovations.

UK Participants

Prof. Lars Johanning

Prof. Lars Johanning, Deputy Head of Engineering Discipline, Chair of Ocean Technology at the University of Exeter, received PhD from Imperial College of Science, Technology and Medicine at 2003.

He has worked in University of Exeter College of Engineering, Mathematics and Physical Sciences since 2007. Now, he is the head of Offshore Renewable Energy.

He is a leading researcher with international recognition in the field of ocean energy and technology with a focus towards hydrodynamics and mooring systems.

During his career Prof. Johanning has led multiple challenging research projects to a successful outcome and has developed the ORE group at Exeter to its current strength. His research outputs include over 130 peer reviewed book chapters, journal and conference papers dedicated to Offshore Renewable Energy and related topics including multi-disciplinary publications on resource characterisation and environmental studies.

Professor Johanning is currently a Visiting Scholar at Dalian University of Technology, a selected Senator at the University of Exeter, Supergen (UKCMER) wave energy lead, and is the programme Director on the Marine-i Hub project, a £6.8m European Regional Development Fund (ERDF) project as part of the Marine Hub Cornwall Enterprise Zone to stimulate and support business-led and market-driven R&D and innovation.

He is a leading researcher with international recognition in the field of ocean energy and technology with a focus towards hydrodynamics and mooring systems.

Dr Philipp Thies

Dr Philipp R. Thies is a Senior Lecturer in Renewable Energy in the College of Engineering, Mathematics and Physical Sciences (CEMPS) at the University of Exeter. He holds a Dipl.-Wi.-Ing. degree in Energy- and Environmental Energy from the University of Flensburg (Germany) and a PhD in Renewable Energy from the University of Exeter (UK).

His research interest lies in the reliability engineering of renewable energy technologies with a focus on offshore energy. He has developed novel component reliability testing approaches, Bayesian statistical analysis approaches for situations of data uncertainty and has been deeply involved in several national and international research and industry-led projects seeking to technology demonstration in the field and at large-scale in the lab. His work has aligned computational modelling with application driven design improvements and extensive planning, execution and evaluation of component reliability and testing campaigns. He was the Principal Investigator in the UK-China Newton Fund Marine Energy Challenge project “Energy absorbing mooring systems: Risk-based investigation for high intensity typhoon conditions in China” (EP/M019942/1).

The project investigated novel mooring solutions for extreme load conditions in China. He also the academic PI on an industry-led project funded by Innovate UK, titled “Dynamic Load Reduction and Station Keeping Mooring System for Floating Offshore Wind” (Grant Ref :101970) and is acting as the Program Lead for the BEng/MEng Energy Engineering.

Dr Philipp Thies

University of Exeter

Prof. Gavin Tabor

Prof. Gavin Tabor is Associate Professor in CFD in the University of Exeter and is based at the Exeter (Streatham) campus. After a PhD in Computational Astrophysics he changed areas to undertake postdoctoral research in CFD at Imperial College, where he was involved in the early development of the OpenFOAM open source CFD code. In 2000 he was appointed to a lectureship at Exeter, developing a world-leading research group in CFD and teaching CFD and fluid dynamics at the UG level.

His research covers a wide range of topics within CFD, including turbulence, combustion, multiphase flow, and applications of CFD in a variety of areas such as biomechanics and renewable energy. Current research projects include work on Machine Learning and CFD for optimisation, solid fuel combustion, simulation of vortex separators used in Urban Drainage applications, simulation of design and manufacture of compact heat exchangers, and of course the ResIn project on floating wind turbines. He is a prominent member of the international OpenFOAM community involved in organising both the UK Users Group and the international Workshop; is a member of the IOP Computational Physics Group committee, and involved in the CCP-WSI collaboration Wave-Structure Interaction.

Prof. Gavin Tabor

University of Exeter

Prof. David Ingram

Prof. David Ingram was awarded a personal chair in Computational Fluid Dynamics by the Court of the University of Edinburgh in June 2009, following his appointment as a Reader in the Institute for Energy Systems in April 2006. He is currently the Director of Discipline for Engineering Mathematics. Previously he was the Schools Director of Research and the Head of the Engineering Graduate School. He joined IES from Manchester Metropolitan University (MMU) where he was Reader in Scientific Computation in the Department of Computing and Mathematics.

He joined MMU as lecturer in Mathematics (specialising in Numerical Analysis) following the completion of his PhD in 1992. David is currently Research Director of the UK Centre for Marine Energy Research (EP/P008682/1, EP/M014738/1 & EP/I027912/1), a £5.3M, interdisciplinary, challenge led, collaborative research programme funded under the RCUK SuperGen programme that coordinates the research work of more than 100 academic and research staff across 25 UK Universities in both the wave and tidal energy sectors. He is also director of the Industrial Doctoral Centre for Offshore Renewable Energy (EP/J500847/1), a £6.5M center that is training 66 EngD students from 2012-2022.

IDCORE is funded by the ETI and the RCUK Energy programme and is run by a consortium of the Universities of Edinburgh, Exeter and Strathclyde, together with the Scottish Association for Marine Science and HRWallingford. David was one of three investigators who secured £6M funding from the EPSRC to design build the £12M FloWave facility, the world’s first, circular, combined wave and current test basin. David has published over 100 journal and conference papers, achieving over 1500 citations with an Hindex of 17 (excluding self-citations). He is named on a patent application (IT-2016-00130691) and is a member of the project team for the IEC 62600-1 standard, and a member of the present

Prof. David Ingram

University of Edinburgh

Prof. Aleksandar Pavic

Prof. Aleksandar Pavic, Professor of Vibration Engineering at the University of Exeter, holds the Chair in Vibration Engineering and leads the Vibration Engineering Section in the Engineering discipline.

Professor Pavic’s expertise is in vibration serviceability of slender civil engineering structures, such as long-span floors, footbridges and grandstands, which are occupied and dynamically excited by humans. He made his academic career by modelling, testing and monitoring full-scale (foot)bridges, floors, grandstands, staircases, long and tall structures, and learning how these structures behave in the real world. A trained bridge engineer, he has keen interests in bridge monitoring and ‘Big Data’ approaches to their management.

This research portfolio is underpinned by advanced research tools such as vibration testing and system identification of as-built large civil engineering structures using full-scale modal testing and finite element model correlation and updating technology based on experimental measurements.

Recently, he extended his interests in human-induced dynamic forces on structures to the same forces but applied on human musculo-skeletal systems and is a co-investigator on a major EPSRC Frontier Engineering grant dealing with this problem.

Professor Pavic is Editor in Chief of Vibration journal and has edited special issues of international journals devoted to vibration performance of civil engineering structures. In addition, his co-authorship or contribution has been recognised in state-of-the-art design guidelines. These are currently used in the UK and internationally for checking vibration serviceability of floors and footbridges

Furthermore, he co-authored and helped experimental verification of worldwide most advanced design guidelines on crowd dynamic loading of grandstands published by the UK Institution of Structural Engineers in 2008. He sat on British Standards Institution (BS6472) and International standardisation Organisation (ISO10137) committees developing standards pertinent to vibration serviceability.

Professor Pavic’s expertise is sought after by industry and he is a Managing Director of Full Scale Dynamics Ltd, a university spin-off company specialised in commercial testing, monitoring and performance assessment of full-scale civil engineering structures.

Professor Pavic is Associate Dean for Research and Knowledge Transfer at the College of Engineering, Mathematics and Physical Sciences and member of the College Executive Group and University's Senior Management Group.

Prof. Aleksandar Pavic

University of Exeter

Dr Venki Venugopal

Dr Venki Venugopal has joined the University of Edinburgh as Lecturer in 2005 and he is currently Reader with the Institute for Energy Systems, School of Engineering.

He received a Bachelor of Technology degree in Civil Engineering (1991), Master of Technology in Ocean Engineering (1994) and PhD in Ocean Engineering (United Kingdom, 2003). His research interests include numerical modelling of wave and tide propagation in ocean and bay scale, wave and tidal power resource modelling, interaction of wave–current-turbulence-marine energy structure modelling, arrays of wave and tidal energy devices modelling, physical modelling of wave and tides in laboratory and their interaction, extreme waves, offshore wind energy, climate change modelling, environmental impact modelling of waves and currents, breakwaters, general offshore structures modelling and ocean wave statistics.

He is currently leading the EPSRC research [FlowTurb project, EP/N021487/1] on the characterisation of combined wave-current-turbulence interactions on tidal energy resources, performance of tidal turbines in turbulent flow conditions, and the resulting fatigue loads on tidal turbine rotor blades and support structures for both floating and seabed fixed tidal turbines. His previous work [EPSRC TeraWatt, EP/J010170/1] explored ways in which marine spatial planning and policy development can enable the maximum level of marine energy extraction, while minimizing environmental impacts.

Dr Venki Venugopal

University of Edinburgh

Dr Jun Zang

Dr Jun Zang is a Reader (Associate Professor), and the Founding Director of the Research Unit for Water, Environment and Infrastructure Resilience (WEIR) at the University of Bath. Prior to joining Bath in 2007, she was a Departmental Lecturer at the University of Oxford. Before that, she took on various roles in both academia and industry after she graduated with a PhD in coastal and offshore engineering from Dalian University of Technology. She was the Chair of the PRIMaRE, a partnership of world-class research institutions based in the West, South, and South West of England for research in marine renewable energy for the academic year 2015-2016.

Dr. Zang’s research group at Bath is one of the international leading groups in developing and using advanced CFD tools in modelling complex free surface flows, violent wave impact on coastal and offshore structures, urban and coastal flooding, and the performance and survivability of wave energy devices.

She has led and participated in multiple national and international large research projects on various topics, which include EU funded project investigating violent wave impact on fixed offshore wind turbine foundations (as Project Leader), several wave energy related projects on the optimisation and survivability of WECs (as Bath Principle Investigator), and wave structure interactions (including CCP-WSI collaboration on wave-structure interaction). She is also a committee member of a couple of top international conferences in the field and chaired major conferences in recent years.

Dr Jun Zang

University of Bath

Dr Chris Blenkinsopp

Dr Chris Blenkinsopp joined the University of Bath in 2013 and is currently a Senior Lecturer in the Department of Architecture and Civil Engineering. Before joining Bath he was a Lecturer at the University of New South Wales, Australia and has also worked as a consultant coastal engineer in the UK and New Zealand. Chris completed his PhD in coastal hydrodynamics at the University of Southampton in 2007.

Chris’ research interest are primarily within the fields of coastal science and coastal/ocean engineering with a particular focus on remote-sensing of coastal processes, coastal adaptation to climate change and sea level rise, beach morphology change during storm erosion and recovery and breaking and broken wave hydrodynamics. He has led and participated in multiple large-scale research projects funded by EPSRC, EU and the Australian Research Council. Most recently he was the PI on the EPSRC “Waves in Shallow Water” project (EPxx) which used novel techniques to obtain the most detailed field measurements of breaking and broken waves to date which enabled new insight into energy dissipation and wave modelling in the surf zone. He is currently leading an EU HydraLab+ project investigating dynamic revetments alongside 12 leading researchers from the UK, Netherlands, France, Belgium, USA and Australia. At the University of Bath he is the University-wide theme leader for Coastal and Ocean Engineering and his research group currently consists of 5 PhD students and 1 PDRA.

Dr Chris Blenkinsopp

University of Bath

Dr Edward Mackay

Ed is a Research Fellow at the University of Exeter. His current research focuses on the hydrodynamics of floating offshore wind platforms and the statistics of extreme loads on offshore structures. Ed has a MSci in Mathematics from the University of Bristol (2003), an MSc in Renewable Energy Systems Technology from the University of Loughborough (2005) and a PhD in Wave Energy Resource Assessment from the University of Southampton (2009).

Prior to joining the University of Exeter, Ed worked in the wave and tidal energy industry for 12years, most recently for Wavepower Technologies, where he led the work on physical testing and numerical modelling of wave energy converters (WECs). Ed also spent 6 years working in the wave and tidal energy group at DNV GL (formerly Garrad Hassan), where he worked on the development of the WaveDyn and WaveFarmer software tools for modelling WECs and WEC arrays.

Dr Edward Mackay

University of Exeter

Dr Qiang Chen

Dr Qiang Chen is currently a PDRA in the WEIR research unit at University of Bath. He received his PhD from University of Bath at 2017.

His research interests include CFD modelling for free-surface flows and fluid-structure interaction, wave/wind/tide renewable energy, coupling effects of sloshing and ship motion and high performance computing. He played a leading role in developing a hybrid particle-mesh Particle-In-Cell method based CFD model for coastal and offshore engineering applications.

Dr Qiang Chen

University of Bath

Dr Wai Kei Ao

Wai Kei (Vincent) Ao graduated from the National Taiwan University (NTU) with MSc and BSc qualifications in Civil and Structural Engineering and Civil Engineering. After the MSc course, he went back to his home town Macau, SAR to work at BAHH Engineering Consultants Ltd, Macau. He worked there for one and a half year. In that time, he did some works including foundation design, structural design, coordinating engineering plans, program design narrative, etc. He joined the Vibration Engineering Section (VES) at the University of Exeter (UoE) in 2013 and studied for a PhD and graduated in 2017 with the research topic on “electromagnetic damping for control of vibration in civil structures”.

After the PhD process, he worked at UoE as a graduate research assistant. In 2018, he was awarded a research fellowship related to advanced sensors and modelling for next-generation bridge management in Queen’s University Belfast (QUB). In 2019, he awarded a new research fellowship at University of Exeter until present. The key aim of UoE job is corresponding to two project grants: ResIn and DynaTTB. These works are focusing on the dynamic behaviour of offshore structures and the dynamic testing of tall timber buildings around UK and Europe.

Dr Wai Kei Ao

University of Exeter

Anna Feichtner

MSc. (DI) Anna Feichtner

Anna Feichtner is a PhD student within the Renewable Energy Group at the Penryn Campus of the College of Engineering, Mathematics and Physical Sciences of the University of Exeter.

Her undergraduate qualification is a BSc and MSc (Dipl.-Ing. / DI) in Civil and Environmental Engineering at the University of Innsbruck, Austria – graduation in 2017.
The objective of her PhD project is to develop CFD simulations (with OpenFOAM) of floating offshore wind turbines in order to study their response to wave forces.

The focus lies on the floating platform and its wave-structure-interaction and the outcome will inform the stability and load prediction in operational and extreme conditions.
Anna’ supervisors are Prof. Gavin Tabor, Prof Lars Johanning and Dr. Philipp R. Thies.

Anna Feichtner

University of Exeter

Rachael Smith

Rachael is a PhD student at the University of Exeter, working as part of the Renewable Energy group in the College of Engineering, Mathematics and Physical Sciences. She is supervised by Prof Lars Johanning, Prof Gavin Tabor and Prof Philipp Thies. Rachael has a BSc in Mathematics and Engineering from the University of Exeter (2016).

The focus of her research is on the influence of aerodynamic models on coupled simulations of floating offshore wind turbines, in which she is using a low order blade element momentum theory based model and a higher order CFD approach to analyse the behaviour of a floating wind turbine in operational and extreme conditions. The objective of her PhD work is to present recommendations for the design of floating offshore wind turbine blades to minimise loads in extreme conditions.

Rachael Smith

University of Exeter

China Participants

Prof. Bing Chen

Prof. Bing Chen is Associate Professor in the Dalian University of Technology and is based at the Panjin campus. After received PhD in Ocean Engineering in 1998 at the State Key Laboratory of Coastal and Offshore Engineering (SLCOE), and following two years of postdoctoral research in CFD at the Department of Engineering Mechanics in DUT, he works in the Department of Hydraulic Engineering in the same university since July, 2000. He was a Visiting Scholar to the University of Western Australia in 2001, and to the Institute for Energy System of the University of Edinburgh in 2011. He transferred from Dalian to the School of Ocean Science and Technology at Panjin campus of DUT since 2013. His research interests covers many aspects of ocean engineering, including wave loads, local scour, and coupling interaction between fluid and structures, mainly by numerical simulations. He has extended his research into the area of marine renewable energy since 2011. He is the PI of the NSFC 2014 general program “Development of a new vertical axis tidal turbine-submerged carrier system”. He was the PI of exchange program “Development of a new buoy-type energy converter” funded jointly by NSFC and Royal Society of Edinburgh (NSFC-RSE, 2013), and the technical director of Special Funding Project (2011) “Laboratory investigation and sea trail of new vertical axis tidal turbine and direct-driven generator system” funded by the State Oceanic Administration (SOA) of China, led the laboratory investigations and took part in the sea trail of the tidal device. He is now serving as the PI of Chinese team of this ResIn project.

Prof. Bing Chen

Dalian University of Technology

Prof. Dezhi Ning

Prof. Dezhi Ning, Deputy Director of Hydraulic Engineering and Vice Dean of State Key Laboratory of Coastal and Offshore Engineering (SLCOE) at Dalian University of Technology (DUT), received PhD from DUT of Coastal and Offshore Engineering in 2005.
Afterwards, he worked as a postdoc at Department of Engineering Science at Oxford University from 2005 to 2007. Prof.

Ning currently serves as the Head of Offshore Renewable Energy Research Centre at DUT, leading one of the top research groups on wave hydrodynamics and wave energy conversion (WEC) in China. He is the Principal Investigator for four NSFC projects on nonlinear wave interaction with marine structures, interaction of extreme wave and uniform current with offshore structures, interaction of extreme wave and moored body, and hydrodynamics of floating OWC Wave Energy Convertor. He also leads a collaborative grant by NSFC and RS for survivability and hydrodynamics of a fixed OWC device, and a Royal Academy of Engineering Project under Newton Fund for the integration of WECs and floating breakwaters. At present, He has published over 120 peer-reviewed journal/conference papers in proposed areas, and chaired UK-China Tidal Energy Collaborative Workshop in 2015 and 32nd International Workshop of Water Waves and Floating Bodies in 2017.

Prof. Dezhi Ning

Dalian University of Technology

Prof. Hai-gui Kang

Prof. Haigui Kang is Professor in the Dalian University of Technology. He was Vice Dean of School of Engineering and Architecture (1996~2002) and Vice Dean of Institute for Energy System (2008~2014) at Dalian University of Technology.

He was a Visiting Scholar at the HR Wallingford UK (1991~1992) and Visiting Professor at Virginia Institute of Marine Science USA (2000). He was the person in charge of UKChina Science and Technology Cooperation Project with the University of Edinburgh which was financial supported by the British Council (2005~2000).

His research interests include marine renewable energy application; physical model testing and numerical simulation of hydrodynamic forces on coastal and offshore structures due to regular waves, irregular waves, and combined wave and current, as well as shoaling of wave spectra. He has developed simultaneous measurement techniques for velocity and concentration fields using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) techniques.

He has extended his research into the area of marine renewable energy since 2006. He was responsible for many research projects of marine renewable energy. Recent years, he leads the Project ”Research on the reliability of foundation supporting structures of offshore wind power” financial supported by the East China Design & Research Institute 2015, the Project “Study on vertical pipe-restrained floating breakwater doubled as wave power generation device" funded by NSFC 2013, and the Special Funding Project “Laboratory investigation and sea trail of new vertical axis tidal turbine and direct-driven generator system” funded by the State Oceanic Administration (SOA) of China 2011.

Prof. Hai-gui Kang

Dalian University of Technology

Prof. Jun Chang

Prof. Jun Chang has worked in building Materials institute of Dalian University of Technology from 2011. His research field mainly focus on special cement for resistance seawater corrosion. received Ph.D. in Materials science at Wuhan University of Technology He rec ogy 2004 and worked as a Visiting professor in McGill University, Montreal, Quebec, Canada on 2005-2006.

His research work mainly focus on special cement materials, which is calcium barium (strontium) sulphoaluminate (CBaSA and CSrSA) cement and it has excellent performance, such as rapid hardening, early strength and high strength, impermeability and seawater corrosion resistance. Calcium barium (strontium) sulphoaluminate cements, plugging materials and concrete interface agent were invented based on CBaSA, CSrSA and C2S minerals.

The award of National prize for technological inventions was obtained based on this research work. The series materials were widely used to repair and strengthening in coastal concrete engineering.

Prof. Jun Chang

Dalian University of Technology

Prof. Dahai Zhang

Associate Professor Dahai Zhang, Vice Deputy Secretary-General of Division of Ocean Technology System, Chinese Society of Oceanography; Vice Deputy Director of the Institute of Ocean Engineering and Technology at Ocean College, Zhejiang University of (ZJU), received PhD from ZJU of Mechanical and Electronic Engineering in 2010.

Afterwards, he worked as a postdoc at Department of Mechanical Engineering at ZJU in 2011 and worked as a postdoc at Department of Engineering in Lancaster University from 2012 to 2013. Associate Professor Zhang has worked with various research projects dealing with modelling, design and measurements of renewable energy electrical machines such as wave energy converter, tidal current turbine and wind turbine. He has published over 40 peer-reviewed journal/conference papers in proposed areas, and chaired 5th China Marine Renewable Energy Conference in 2016 and 3th China Ocean Technology Conference as organizing president in 2017.

Prof. Dahai Zhang

Zhejiang University

Dr Ying Gou

Dr Ying Gou is Associate Professor in the Dalian University of Technology. She joined DUT as Lecture after received PhD of Coastal and Offshore Engineering from DUT in 2006. She worked as a postdoc at Department of Naval Architecture and Ocean Engineering in Seoul National University for one year from 2010 to 2011.

Her research interests include numerical modelling of wave interactions with multiple floating bodies, hydrodynamic characteristic of ocean structures in twolayer fluid, hydroelastic response of very large floating structures and the acceleration technology of Boundary element method. She was the Principal Investigator of NSFC projects ‘Analysis of the hydrodynamics of mooring multi-floating bodies under wave actions in frequency and time domain’ and the Co-PI of NSFC project ‘Hydrodynamic research and optimum design of a new-style bottom-hinged flap wave energy device’. She is currently in charge of the NSFC project ‘Study of slow-drift motions of large floating structures in two-layer fluid’.

Dr Ying Gou

Dalian University of Technology

Prof. Wei Shi

Dr. Wei Shi, an associate professor of Deepwater Engineering Research Centre at Dalian University of Technology (DUT), received PhD from POSTECH in Korea in 2013. Afterwards, he worked as an assistant professor in Konkuk University in 2013 and postdoc at Department of Marine Technology at NTNU in Norway from 2014 to 2017.

His research interests include numerical modelling of both fixed-bottom and floating offshore wind turbine, wind turbine drivetrain dynamics, ice-structure interaction for offshore wind turbine. Meanwhile he has a good experience in dynamic analysis of mechanical system. He is serving as an international advisory committee in Asia- Pacific Forum on Renewable Energy 2017.

Prof. Wei Shi

Dalian University of Technology

Dr Dongsheng Qiao

Dr Dongsheng Qiao is Associate Professor of Deepwater Engineering Research Center, Dalian University of Technology.

His research interest lies in the analysis of floating platform and its mooring system, numerical simulation and experimental study on hybrid model testing method of floating platform. He has developed a concept design of mooring line with buoys, passive and active truncated design of mooring system in the hybrid model test of floating platform, trajectory prediction of plate anchor.

Dr Dongsheng Qiao

Dalian University of Technology

Dr Nianxin Ren

Dr Nianxin Ren has joined at the Dalian University of Technology as a Lecturer since 2012. He received a PhD in Engineering Mechanics in 2011 at the Harbin Institute of Technology (HIT), and he worked as a postdoctor at Center for Ships (CeSOS) and Ocean Structures at Norwegian University of Science and Technology (NTNU) for two years (from 2013.05 to 2015.03).

His research interests covers many aspects of offshore renewable energy, including floating offshore wind turbine, typhoon extreme loads, novel combined wind turbine and wave energy systems and CFD simulation, mainly by coupled aero-hydro dynamic simulations and scale model tests. He has joined the European Communities Program: Marine Renewable integrated Application Platform” (2013-2015). He is the PI of the NSFC 2017 Youth scholar program “Multi-body dynamic coupling effect study of a novel wind energy and wave energy combined structure system”. At present, He has published over 30 peer-reviewed journal/conference papers and 3 patents for invention in proposed areas.

Dr Nianxin Ren

Dalian University of Technology