Export file:


  • RIS(for EndNote,Reference Manager,ProCite)
  • BibTex
  • Text


  • Citation Only
  • Citation and Abstract

Business and policy models to incentivise utilities to engage with demand-side management

University College London, 29/31 Tavistock Square, London, WC1H 9QU, UK

Special Issues: Finance and Sustainability

Business and policy models to incentivise utilities to engage with demand-side management (DSM) have received more attention in the grey literature than the academic literature. This review paper contributes to filling this gap by reviewing theoretical frameworks for four key categories of business models and how they relate to policy models that enable their implementation. The paper proposes a theoretical lens through which to visualise the different frameworks. The review discusses the key benefits and challenges for utilities to engage with DSM, and finds that deferred investment in new generation capacity, new business opportunities and services, and dealing with variable power production are the primary benefits, and limited incentives to invest in markets based on the quantity of energy sold and cost recovery issues (such as DSM programme costs) are the main challenges. The paper reviews four primary business and policy models: decoupling, demand-side participation in capacity markets, utility obligations and Energy Service Companies (ESCOs), and finds that despite the limitations of the evidence base on the applicability of decoupling in fully liberalised markets, demand-side participation in capacity markets, utility obligations and ESCOs appear to be applicable across contexts.
  Article Metrics

Keywords demand-side management; decoupling; capacity markets; utility obligations; ESCOs; energy efficiency

Citation: Peter Warren. Business and policy models to incentivise utilities to engage with demand-side management. Green Finance, 2019, 1(1): 4-29. doi: 10.3934/GF.2019.1.4


  • 1. Albadi El-Saadany (2008) A summary of demand response in electricity markets. Electr Power Syst Res 78: 1989–1996.    
  • 2. American Council for an Energy-Efficient Economy (ACEEE). Available from: http://aceee.org.
  • 3. Baxter LW (1995) Net Lost Revenue Adjustment (NLRA) Mechanisms for Utility DSM Programs. Energy 20: 1215–1223.    
  • 4. Behrangrad M (2015) A review of demand side management business models in the electricity market. Renewable Sustainable Energy Rev 47: 270–283.    
  • 5. Berg W, Nowak S, Kelly M, et al. (2016) The 2016 State Energy Efficiency Scorecard. Research Report U1606, American Council for an Energy-Efficient Economy (ACEEE).
  • 6. Bertoldi P, Labanca N, Rezessy S, et al. (2013) Where to place the saving obligation: Energy end-users or suppliers? Energy Policy 63: 328–337.    
  • 7. Bertoldi P, Rezessy S, Anable J, et al. (2011) Energy Saving Obligations and White Certificates: Ideas and Considerations for the Transport Sector, Int J Sustainable Transp 5: 345–374.
  • 8. Bertoldi P, Rezessy S, Lees E, et al. (2010) Energy supplier obligations and white certificate schemes: Comparative analysis of experiences in the European Union. Energy Policy 38: 1455–1469.    
  • 9. Bertrand A, Mian A, Kantor I, et al. (2019) Regional waste heat valorisation: A mixed integer linear programming method for energy service companies. Energy, 167: 454–468.    
  • 10. Bhattacharyya SC (2011) Energy Economics: Concepts, Issues, Markets and Governance, Springer.
  • 11. Bigliani R, Eastman R, Segalotto J, et al. (2015) Designing the new utility business models. White paper, Energy Insights IDC.
  • 12. Boait P (2009) Energy services and ESCos-their benefits and implications for regulation and the consumer, research report, De Montfort University, UK.
  • 13. Bundgaard SS, Dyhr-Mikkelsen K, Larsen AE, et al. (2013a) Energy Efficiency Obligation Schemes in the EU-Lessons Learned from Denmark. First quarter 2013, Int Assoc Energy Econ (IAEE).
  • 14. Bundgaard SS, Togeby M, Dyhr-Mikkelsen K, et al. (2013b) Spending to save: Evaluation of the energy efficiency obligation in Denmark. ECEEE Summer Study 2013 Proceedings, European Council for an Energy-Efficient Economy (ECEEE).
  • 15. Bureau of Energy Efficiency (BEE) (2015) National Mission for Enhanced Energy Efficiency, Ministry of Power, Government of India, Available from: https://www.beeindia.gov.in/content/nmeee-1.
  • 16. CAISO (California Independent System Operator). Available from: http://www.caiso.com/Pages/default.aspx.
  • 17. Capgemini (2008) Demand Response: A decisive breakthrough for Europe, in collaboration with Vaasaett and Enerdata.
  • 18. Chapman AC, Verbic G (2017) An iterative on-line auction mechanism for aggregated demand-side participation. IEEE Trans Smart Grid 8: 158–168.    
  • 19. Chen Y, Nie P, Yang Y (2017) Energy management contract with subsidy. J Renewable Sustainable Energy 9: 055903.    
  • 20. Cheng C (2005) Electricity demand-side management for an energy efficient future in China: Technology options and policy priorities, PhD Thesis, Massachusetts Institute of Technology, USA, 43.
  • 21. Chinnow J, Bsufka K, Schmidt AD, et al. (2011) A simulation framework for smart meter security evaluation. 2011 IEEE International Conference on Smart Measurements for Future Grids (SMFG), 1–9, 14–16th November 2011.
  • 22. Cooke D (2011) Empowering Customer Choice in Electricity Markets, Information Paper, October 2011, International Energy Agency (IEA).
  • 23. Crossley D (2010) International best practice in using energy efficiency and demand management to support electricity networks. Report 4-Scaling the Peaks: Demand Management and Electricity Networks, Australian Alliance to Save Energy, Australia.
  • 24. Crossley D (2011) Tempo Electricity Tariff-France. 11th case study article of Task XV-Network-Driven DSM, IEA DSM Programme.
  • 25. Crossley D (2013) Effective mechanisms to increase the use of demand-side resources. Global Power Best Practice Series, Regulatory Assistance Project (RAP).
  • 26. Crossley D, Maloney M, Watt G (2000) Developing mechanisms for promoting demand-side management and energy efficiency in changing electricity businesses. IEA DSM Programme, Task VI Research Report No. 3, Energy Futures Australia, August 2000.
  • 27. Darby S (2006) The effectiveness of feedback on energy consumption–a review for DEFRA, Environmental Change Institute, University of Oxford.
  • 28. Data Communications Company (DCC). Available from: https://www.smartdcc.co.uk.
  • 29. Department for Business, Energy & Industrial Strategy (BEIS) (2017a), Electricity Demand Reduction Pilot-Interim Evaluation Findings, February 2017, UK Government.
  • 30. Department for Business, Energy & Industrial Strategy (BEIS) (2017b) Realising the potential of demand-side response to 2025: A focus on small energy users, UK Government.
  • 31. Department for Business, Energy & Industrial Strategy (BEIS) (2016) Evidence Gathering: Thermal Energy Storage (TES) Technologies, UK Government.
  • 32. Department of Energy (DoE) (2017) Federal Energy Management Program. Department of Energy, Washington, USA. Available from: https://energy.gov/eere/femp/about-federal-energy-management-program.
  • 33. Depuru SSSR, Wang L, Devabhaktuni V (2011) Smart meters for power grid: Challenges, issues, advantages and status. Renewable Sustainable Energy Rev 15: 2736–2742.    
  • 34. Devine-Wright H, Devine-Wright P (2004) From demand side management to demand side participation: Tracing an environmental psychology of sustainable electricity system evolution. J Appl Psychol 6: 167–177.
  • 35. Didden MH, D'haeseleer WD (2003) Demand Side Management in a competitive European market: Who should be responsible for its implementation?. Energy Policy 31: 1307–1314.    
  • 36. Dreessen T (2003) Advantages and disadvantages of the two world ESCO models: Shared savings and guaranteed savings, in: Proceedings of the First Pan-European Conference on Energy Service Companies.
  • 37. Efficiency Vermont (2016a) Available from: https://www.efficiencyvermont.com/about/history.
  • 38. Efficiency Vermont (2016b) Available from: Annual Report 2015, Efficiency Vermont, Burlington: Vermont, USA, October 2016.
  • 39. EfficiencyOne (2015). Available from: https://www.efficiencyone.ca/who-we-are/.
  • 40. El Bakari K, Myrzik JMA, Kling WL (2009) Prospects of a virtual power plant to control a cluster of distributed generation and renewable energy sources, 2009 Proceedings of the 44th International Universities Power Engineering Conference (UPEC),1–5, 1–4th September 2009, Glasgow.
  • 41. Energy Efficiency Services Limited (EESL) (2015) Available from: http://www.eeslindia.org/User_Panel/UserView.aspx?TypeID=1025&p=About%20Us.
  • 42. ERCOT (Electric Reliability Council of Texas). Available from: http://www.ercot.com.
  • 43. Eto J, Stoft S, Belden T (1997) The theory and practice of decoupling utility revenues from sales. Util Policy 6: 43–55.    
  • 44. Eto JH (1994) The theory and practice of decoupling. eScholarship, Lawrence Berkeley Laboratory, USA.
  • 45. European Commission (2015) Energy Efficiency-Energy Performance Contracting. Available from: http://iet.jrc.ec.europa.eu/energyefficiency/european-energy-service-companies/energy-performance-contracting.
  • 46. European Council Directive 2009/72/EC on smart meter rollout.
  • 47. European Union Directive 2012/27/EU on energy efficiency.
  • 48. Eyre N, Pavan M, Bodineau L (2009) Energy company obligations to save energy in Italy, the UK and France: What have we learnt?. ECEEE Summer Study 2013 Proceedings, European Council for an Energy-Efficient Economy (ECEEE).
  • 49. Fattahi A, Nahavandi A, Jokarzadeh M (2018) A comprehensive reserve allocation method in a micro-grid considering renewable generation intermittency and demand side participation. Energy 155: 678–689.    
  • 50. Federal Energy Management Program (FEMP) (2016) Overview-Federal Energy Management Program. Department of Energy, Washington, USA, Available from: https://energy.gov/sites/prod/files/2016/08/f33/femp_overview.pdf.
  • 51. Fetter J, Thomas S, Potes A, et al. (2012) Energy Efficiency in the Forward Capacity Market: Evaluating the Business Case for Building Energy Efficiency as a Resource for the Electric Grid. 2012 ACEEE Summer Study on Energy Efficiency in Buildings, American Council for an Energy-Efficient Economy (ACEEE), USA.
  • 52. Gillingham K, Newell RG, Palmer K (2009) Energy efficiency economics and policy. Annual Review of Resource Economics, NBER Working Paper Series, National Bureau of Economic Research.
  • 53. Granovetter MS (1973) The strength of weak ties. Am J Sociol 78: 1360–1380.    
  • 54. Haas R, Nakicenovic N, Ajanovic A, et al. (2008) Towards sustainability of energy systems: A primer on how to apply the concept of energy services to identify necessary trends and policies. Energy Policy 36: 4012–4021.    
  • 55. Hamidi V, Li F, Robinson F (2009) Demand Response in the UK's domestic sector. Electr Power Syst Res 79: 1722–1726.    
  • 56. Hamilton B, Plunkett J, Wickenden M (2002) Gauging success of the nation's first efficiency utility: Efficiency Vermont's first two years. 2002 ACEEE Summer Study on Energy Efficiency in Buildings-Proceedings, American Council for an Energy-Efficient Economy (ACEEE), USA.
  • 57. Hannon M, Foxon TJ, Gale WF (2013) The co-evolutionary relationship between Energy Service Companies and the UK energy system: Implications for a low-carbon transition. Energy Policy 61: 1031–1045.    
  • 58. Hargreaves T, Nye M, Burgess J (2010) Making energy visible: A qualitative field study of how householders interact with feedback from smart energy monitors. Energy Policy 38: 6111–6119.    
  • 59. Hayes S, Nadel S, Kushler M, et al. (2011) Carrots for Utilities: Providing Financial Returns for Utility Investments in Energy Efficiency. Report Number U111, American Council for an Energy-Efficient Economy (ACEEE), Washington DC, USA.
  • 60. Hienerth C, Keinz P, Lettl C (2011) Exploring the nature and implementation of user-centred business models. Long Range Plann 44: 344–374.    
  • 61. Hills J (2012) Getting the measure of fuel poverty-final report of the Fuel Poverty Review. CASE report 72, Centre for Analysis of Social Exclusion (CASE), March 2012.
  • 62. Hirst E (2002) The financial and physical insurance benefits of price-responsive demand. Electr J 4: 66–73.
  • 63. Hirst E, Blank E (1994) Solutions to regulatory disincentives for utility DSM programmes. Util Policy 4: 105–112.    
  • 64. Home Energy Conservation Act of 1996, London: HMSO, UK.
  • 65. ICF International (2007) Introduction to energy performance contracting, report prepared for the US Environmental Protection Agency (EPA), USA.
  • 66. IEA (2015) Energy Efficiency Market Report 2015, International Energy Agency, Paris: France.
  • 67. IEA DSM Programme (2008) Evaluation and Acquisition of Network-driven DSM Resources. Task 15-Network driven DSM, International Energy Agency (IEA).
  • 68. International Energy Agency Demand-Side Management Technology Collaboration Programme (IEA DSM TCP) Task 25-Business models for a more effective market update of DSM energy services. Available from: http://www.ieadsm.org/task/task-25-business-models-for-a-more-effective-uptake/.
  • 69. International Finance Corporation (IFC) (2011) IFC Energy Service Company Market Analysis, Final Report (Revised), 23rd June 2011. Available from: http://www.ifc.org/wps/wcm/connect/dbaaf8804aabab1c978dd79e0dc67fc6/IFC+EE+ESCOS+Market+Analysis.pdf?MOD=AJPERES.
  • 70. ISO-NE (ISO-New England). Available from: https://www.iso-ne.com.
  • 71. Johnson-Brown J, Reingen PH (1987) Social ties and word-of-mouth referral behaviour. J Consum Res 14.
  • 72. Kangas HL, Lazarevic D, Kivimaa P (2018) Technical skills, disinterest and non-functional regulation: Barriers to building energy efficiency in Finland viewed by energy service companies. Energy Policy 114: 63–76.    
  • 73. Kim JH, Shcherbakova A (2011) Common failures of demand response. Energy 36: 873–880.    
  • 74. Kushler M, York D, Witte P (2006) Aligning Utility Interests with Energy Efficiency Objectives: A Review of Recent Efforts at Decoupling and Performance Incentives. Report Number U061, American Council for an Energy-Efficient Economy (ACEEE), Washington DC, USA.
  • 75. Lise W, Kruseman G (2008) Long-term price and environmental effects in a liberalized electricity market. Energy Econ 30: 230–248.
  • 76. Liu Y (2017) Demand response and energy efficiency in the capacity resource procurement: Case studies of forward capacity markets in ISO New England, PJM and Great Britain. Energy Policy 100: 271–282.    
  • 77. Lovins AB (1990) The negawatts revolution. Conference Board Magasine 27: 18–23.
  • 78. Marino A, Bertoldi P, Rezessy S (2010) Energy Service Companies Market in Europe: Status Report 2010. Joint Research Centre (JRC) European Commission, EUR 24516 EN-2010, Italy.
  • 79. Marino A, Bertoldi P, Rezessy S, et al. (2011) A snapshot of the European energy service market in 2010 and policy recommendations to foster a further market development. Energy Policy 39: 6190–6198.    
  • 80. Martínez Ceseña EA, Good N, Mancarella P (2015) Electrical network capacity support from demand side response: Techno-economic assessment of potential business cases for small commercial and residential end-users. Energy Policy 82: 222–232.    
  • 81. Mau P, Eyzaguirre J, Jaccard M, et al. (2008) The 'neighbour effect': Simulating dynamics in consumer preferences for new vehicle technologies. Ecological Economics 68: 504–516.    
  • 82. MISO (Midcontinent Independent System Operator). Available from: https://www.misoenergy.org/Pages/Home.aspx.
  • 83. Molina M, Kushler M (2015) Policies Matter: Creating a Foundation for an Energy-Efficient Utility of the Future. ACEEE White Paper, American Council for an Energy-Efficient Economy (ACEEE), Washington DC, USA.
  • 84. Mourik R, Bouwknegt R (2017) Mind your business: Entrepreneurs, their dynamic capabilities, context and new business models for energy efficiency services. ECEEE Summer Study 2017 Proceedings, European Council for an Energy-Efficient Economy (ECEEE).
  • 85. Murray J (2015) First government auction pays companies to power down. businessGreen, 4th February 2015. Available from: http://www.businessgreen.com/bg/news/2393653/first-government-auction-pays-companies-to-power-down-at-peak-times.
  • 86. Narayanamurthy R, Robinson J (2015) Bring Your Own Device Program Approaches. Palo Alto, Electric Power Research Institute (EPRI), California, USA.
  • 87. Natural Resources Defense Council (NRDC) (2013) Decoupling Across the United States. Map, August 2013. Available from: http://www.nrdc.org/energy/decoupling.
  • 88. Natural Resources Defense Council (NRDC) (2016) The Evidence Is In: Decoupling Spurs Energy Efficiency Investment. Available from: https://www.nrdc.org/experts/samantha-williams/evidence-decoupling-spurs-energy-efficiency-investment.
  • 89. Natural Resources Defense Council (NRDC). Available from: https://www.nrdc.org.
  • 90. Newborough M, Augood P (1999) Demand-side management opportunities for the UK domestic sector. IEE Proceedings-C Generation, Transmission and Distribution 146: 283–293.    
  • 91. Nilsson H, Bangens L, Goven B, et al. (2012) We are lost if we don't develop new business models. ECEEE Summer Study 2012 Proceedings, European Council for an Energy-Efficient Economy (ECEEE).
  • 92. Nowak S, Baatz B, Gilleo A, et al. (2015) Beyond carrots for utilities: A national review of performance incentives for energy efficiency. Research Report U1504, American Council for an Energy-Efficient Economy (ACEEE), June 2015.
  • 93. NYISO (New York Independent System Operator). Available from: http://www.nyiso.com/public/index.jsp.
  • 94. Oikonomou V, Di Giacomo M, Russolillo D, et al. (2012) White Certificates in the Italian Energy Oligopoly Market. Energy Sources Part B-Economics Plann Policy 7: 104–111.    
  • 95. Oikonomou V, Jepma C, Becchis F, et al. (2008) White Certificates for energy efficiency improvement with energy taxes: A theoretical economic model. Energy Econ 30: 3044–3062.    
  • 96. Oikonomou V, Patel MK, van der Gaast W, et al. (2009) Voluntary agreements with white certificates for energy efficiency improvement as a hybrid policy instrument. Energy Policy 37: 1970–1982.    
  • 97. Otashu JI, Baldea M (2018) Grid-level "battery" operation of chemical processes and demand-side participation in short-term electricity markets. Appl Energy 220: 562–575.    
  • 98. Owen G, Pooley M, Ward J (2012) What demand side services could household customers offer?. Paper 3 of the GB Electricity Demand-realising the resource project, Sustainability First, April 2012, UK.
  • 99. Owens S, Driffil L (2008) How to change attitudes and behaviours in the context of energy. Energy Policy 36: 4412–4418.    
  • 100.Pachauri S, Ürge-Vorsatz D, LaBelle M (2012) Synergies between energy efficiency and energy access policies and strategies. Global Policy 3: 187–197.    
  • 101.Parrish B, Heptonstall P, Gross R (2016) The potential for UK residential demand-side participation. System Architecture Challenges: Supergen + for HubNet, HubNet.
  • 102.Paterakis NG, Erdinç O, Catalão PS (2017) An overview of demand response: Key elements and international experience. Renewable Sustainable Energy Rev 69: 871–891.    
  • 103.PJM (2017) Demand Response Fact Sheet. Available from: https://www.pjm.com/~/media/about-pjm/newsroom/fact-sheets/demand-response-fact-sheet.ashx.
  • 104.PJM, Available from: http://www.pjm.com.
  • 105.Poudineh R, Jamasb T (2014) Distributed generation, storage, demand response and energy efficiency as alternatives to grid capacity enhancement. Energy Policy 67: 222–231.    
  • 106.Prüggler N (2003) Economic potential of demand response at household level-are Central-European market conditions sufficient?. Energy Policy 60: 487–498.
  • 107.Regulatory Assistance Project (RAP), Available from: http://www.raponline.org.
  • 108.Rosenow J (2012) Energy savings obligations in the UK-A history of change. Energy Policy 49: 373–382.    
  • 109.Rosenow J, Galvin R (2013) Evaluating the evaluations: Evidence from energy efficiency programmes in Germany and the UK. Energy Build 62: 450–458.    
  • 110.Rosenow J, Platt R, Flanagan B (2013) Fuel poverty and energy efficiency obligations-A critical assessment of the supplier obligation in the UK. Energy Policy 62: 1194–1203.    
  • 111.Saker D, Coker P, Vahdati M, et al. (2013) Unlocking the demand response potential from domestic hot water tanks. 4th Annual TSBE (Technologies for Sustainable Built Environments) EngD Conference Proceedings, University of Reading, UK.
  • 112.Satchwell A, Cappers P, Goldman C (2011) Carrots and sticks: A comprehensive business model for the successful achievement of energy efficiency resource standards. Util Policy 19: 218–225.    
  • 113.Schultz D, Eto J (1990) Carrots and sticks: Shared-savings incentive programs for energy efficiency. Electr J 3: 32–46.
  • 114.Spees K, Lave LB (2007) Demand response and electricity market efficiency. Electr J 20: 69–85.
  • 115.Steinberger JK, van Niel J, Bourg D (2009) Profiting from negawatts: Reducing absolute consumption and emissions through a performance-based energy economy. Energy Policy 37: 361–370.    
  • 116.Stoker L (2017) Electricity Demand Reduction pilot reports positive interim results. Clean Energy News, 10th February 2017. Available from: http://www.cleanenergynews.co.uk/news/efficiency/electricity-demand-reduction-pilot-reports-positive-interim-results.
  • 117.Strachan N, Warren P (2011) Incorporating behavioural complexity in energy-economic models. UK Energy Research Centre Conference on: Energy and People: Futures, Complexity and Challenges, 20–21 September 2011, Environmental Change Institute, Oxford, UK.
  • 118.Strbac G (2008) Demand side management: Benefits and challenges. Energy Policy 36: 4419–4426.    
  • 119.Stromback J, Dromacque C, Yassin MH (2011) The potential of smart meter enabled programs to increase energy and systems efficiency: A mass pilot comparison, Vaasaett, 13.
  • 120.The Electricity Journal. Available from: https://www.journals.elsevier.com/the-electricity-journal.
  • 121.THINK (2012) How to refurbish all buildings by 2050. Topic 7, Final report, THINK, June 2012.
  • 122.Titus E, Michals J, Hurley D, et al. (2009) Energy efficiency as a resource in the PJM Capacity Market. Int Energy Program Eval Conf 2009.
  • 123.Torriti J, Hassan MG, Leach M (2010) Demand response experience in Europe: Policies, programmes and implementation. Energy 35: 1575–1583.    
  • 124.United Nations/Framework Convention on Climate Change (2015) Adoption of the Paris Agreement, 21st Conference of the Parties, Paris: United Nations.
  • 125.Ürge-Vorsatz D, Hauff J (2001) Drivers of market transformation: Analysis of the Hungarian lighting success story. Energy Policy 29: 801–810.    
  • 126.Utilities Policy: https://www.journals.elsevier.com/utilities-policy.
  • 127.Vermont Public Service Department (2014) Energy Efficiency. Available from: http://publicservice.vermont.gov/topics/energy_efficiency.
  • 128.Walawalkar R, Fernands S, Thakur N, et al. (2010) Evolution and current status of demand response (DR) in electricity markets: Insights from PJM and NYISO. Energy 35: 1553–1560.    
  • 129.Ward J, Pooley M, Owen G (2012) What demand-side services can provide value to the electricity sector?. Paper 4, GB Electricity Demand-Realising the Resource, Sustainability First, June 2012.
  • 130.Warren P (2014) The use of systematic reviews to analyse demand-side management policy. Energy Effic 7: 417–427.    
  • 131.Warren P (2014b) A review of demand-side management policy in the UK. Renewable Sustainable Energy Rev 29: 941–951.
  • 132.Warren P (2015) Demand-Side Management Policy: Mechanisms for Success and Failure, PhD Thesis, University College London (UCL), UK.
  • 133.Warren P (2017a) The potential of smart technologies and micro-generation in UK SMEs. Energies 10.
  • 134.Warren P (2017b) Transferability of demand-side policies between countries. Energy Policy 109: 757–766.
  • 135.Warren P (2018) Demand-side policy: Global evidence base and implementation patterns. Energy Environ 29: 706–731.    
  • 136.Warren P (2019) Demand-side policy: Mechanisms for success and failure. Econ Energy Environ Policy.


Reader Comments

your name: *   your email: *  

© 2019 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

Download full text in PDF

Export Citation

Copyright © AIMS Press All Rights Reserved