Tampere University of Technology

TUTCRIS Research Portal

Life Cycle Effectiveness of the Built Environment (LCE@BE)

Research unit: Research Community

101 - 150 out of 158Page size: 50
Sort by: Type
  1. Article › Scientific › Peer-reviewed
  2. Published

    Utilization of Fuel Consumption Data in an Ecodriving Incentive System for Heavy-Duty Vehicle Drivers

    Liimatainen, H., 2011, In : IEEE Transactions on Intelligent Transportation Systems. 12, 4, p. 1087-1095

    Research output: Contribution to journal › Article › Scientific › peer-review

    Full text: ExLibris SFX link
  3. Published

    Utilization relevance vector machine for slope reliability analysis

    Samui, P., Länsivaara, T. & Kim, D., 2011, In : Applied Soft Computing. 11, 5, p. 4036-4040

    Research output: Contribution to journal › Article › Scientific › peer-review

    Full text: ExLibris SFX link
  4. Published

    Weight and cost optimization of welded high strength steel beams

    Mela, K. & Heinisuo, M., 2014, In : Engineering Structures. 79, p. 354-364 11 p.

    Research output: Contribution to journal › Article › Scientific › peer-review

    Full text: ExLibris SFX link
  5. Published

    Weighting function selection problem in the Galerkin method

    Salonen, E-M., Kouhia, R. & Holopainen, R., 2013, In : International Journal of Mechanical Engineering Education. 41, 2, p. 115-135 21 p.

    Research output: Contribution to journal › Article › Scientific › peer-review

    Full text: ExLibris SFX link
  6. Published

    Work environment preferences - does age make a difference?

    Rothe, P., Lindholm, A. L., Hyvönen, A. & Nenonen, S., Jan 2012, In : Facilities. 30, 1, p. 78-95 18 p.

    Research output: Contribution to journal › Article › Scientific › peer-review

    Full text: ExLibris SFX link
  7. Article › Professional
  8. Published

    After 150 years Pretoria's Fountains still a source of life

    Juuti, P., Mäki, H. & Haarhoff, J., 2011, In : THE WATER WHEEL. 2011, Water Wheel 11, 4, p. 18-23 5 p.

    Research output: Contribution to journal › Article › Professional

    Full text: ExLibris SFX link
  9. Review Article › Scientific › Peer-reviewed
  10. Published

    A case for strong municipal governance: the water supply of Pretoria 1855-1935

    Juuti, P., Haarhoff, J. & Mäki, H., 2012, In : SOUTH AFRICAN HISTORICAL JOURNAL. 64, 4, p. 769-786 18 p.

    Research output: Contribution to journal › Review Article › Scientific › peer-review

    Full text: ExLibris SFX link
  11. Published

    Private initiatives in Finland and South Africa: Proposals for waterworks by von Nottbeck and Marks.

    Juuti, P., Mäki, H. & Rajala, R., 2011, In : Water History. Water History 3 (1), p. 29-43 15 p.

    Research output: Contribution to journal › Review Article › Scientific › peer-review

    Full text: ExLibris SFX link
  12. Published

    Review of Low-Energy Construction, Air Tightness, Ventilation Strategies And Indoor Radon: Results From Finnish Houses and Apartments

    Arvela, H., Holmgren, O., Reisbacka, H. & Vinha, J., 2014, In : Radiation Protection Dosimetry. 162, 3, p. 351-363 13 p.

    Research output: Contribution to journal › Review Article › Scientific › peer-review

    Full text: ExLibris SFX link
  13. Published

    Water supply and sanitation services in finland before world war 2

    Juuti, P. & Katko, T., 2014, In : Flux. 97-98, 4, p. 80-87 8 p.

    Research output: Contribution to journal › Review Article › Scientific › peer-review

    Full text: ExLibris SFX link
  14. Literature review › Scientific › Peer-reviewed
  15. Published

    Experts' view on Finland's energy policy

    Valkila, N. & Saari, A., Jan 2013, In : Renewable and Sustainable Energy Reviews. 17, p. 283-290 8 p.

    Research output: Contribution to journal › Literature review › Scientific › peer-review

    Full text: ExLibris SFX link
  16. Chapter › Scientific › Peer-reviewed
  17. Published

    Complementary paradigms of water and sanitation services: Lessons from the Finnish experience

    Hukka, J. J. & Katko, T. S., 2009, Water and Sanitation Services. Public Policy and Management. Castro, J. E. & Heller, L. (eds.). Earthscan, p. 153-172

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  18. Published

    Decentralized services: The Nordic experience

    Pietilä, P., Gunnarsdóttir, M. J., Hjorth, P. & Balslev Nielsen, S., 2009, Water and Sanitation Services. Public Policy and Management. Castro, J. E. & Heller, L. (eds.). Earthscan, p. 218-233

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  19. Published

    Failure Simulations with a Strain Rate Dependent Ductile-to-Brittle Transition Model

    Hartikainen, J., Kolari, K. & Kouhia, R., 2013, Numerical Methods for Differential Equations, Optimization, and Technological Problems. Repin, S., Tiihonen, T. & Tuovinen, T. (eds.). Springer, p. 431-444 14 p. (Computational Methods in Applied Sciences; vol. 27).

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  20. Published

    Finland – R&D functions in real estate and the construction industry

    Nenonen, S., Airaksinen, M. & Vainio, T., 1 Jan 2014, R and D Investment and Impact in the Global Construction Industry. Taylor and Francis Ltd., p. 98-114 17 p.

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  21. Published

    Management and organization of water and sanitation services: European experiences

    Seppälä, O. T. & Katko, T. S., 2009, Water and Sanitation Services. Public Policy and Management. Castro, J. E. & Heller, L. (eds.). Earthscan, p. 86-103 18 p.

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  22. Published

    Numerical modeling and experimentation of dynamic indentation with single and triple indenters on Kuru granite

    Saksala, T., Gomon, D., Hokka, M. & Kuokkala, V-T., 2013, Rock Dynamics and Applications - State of the Art, Proceedings of the first international conference on rock dynamics and applications, RocDyn-1, Lausanne, Switzerland, 6-8 June 2013. Zhao, J. & Li, J. (eds.). Boca Raton: CRC Press Taylor & Francis Group : A Belkema Book, p. 415-421 7 p.

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  23. Published

    Perspectives on the limited emergence of public private partnerships in Finland

    Valkama, P., Oulasvirta, L. & Karppi, I., 16 Sep 2015, Public Private Partnerships: A Global Review. Taylor and Francis Inc., p. 89-99 11 p.

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  24. Published

    The usability of facilities: Experiences and effects

    Lindahl, G., Hansen, G. & Alexander, K., 2013, Managing Organizational Ecologies: Space, Management and Organizations. Taylor and Francis Ltd., p. 105-116 12 p.

    Research output: Chapter in Book/Report/Conference proceeding › Chapter › Scientific › peer-review

    Full text: ExLibris SFX link
  25. Conference contribution › Scientific › Not peer-reviewed
  26. Published

    Impact Modeling by Manifold Approach in Explicit Transient Dynamics

    Saksala, T. & Mäkinen, J., 2011, COMPDYN 2011, 3rd International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, 25-28 May 2011, Corfu, Greece. Corfu: COMPDYN, p. 1-13 13 p. (International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering COMPDYN).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific

    Full text: ExLibris SFX link
  27. Conference contribution › Scientific › Peer-reviewed
  28. Published

    Anisotropic total and effective stress stability analysis of the Perniö failure test

    D'Ignazio, M., Mansikkamäki, J. & Länsivaara, T., 2014, Numerical Methods in Geotechnical Engineering : Proceedings of the 8th European Conference on Numerical Methods in Geotechnical Engineering NUMGE2014, Delft, The Netherlands, 18-20 June 2014. Hicks, M. A. ., Brinkgreve, R. B. . J. . & Rohe, A. (eds.). CRC Press Taylor & Francis Group; A Balkema book, p. 609-614 6 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  29. Published

    Application of phase change materials in building structures in Nordic climate

    Kiviste, M. & Lindberg, R., 2014, 14th International Multidisciplinary Scientific GeoConference SGEM 2014, GeoConference on NANO, BIO AND GREEN - TECHNOLOGIES FOR A SUSTAINABLE FUTURE, Conference Proceedings, Volume II, Section: Green Buildings Technologies and Materials, Section: Green Design and Sustainable Architecture, 17 - 26 June, 2014, Albena, Bulgaria. SGEM, p. 49-56 8 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  30. Published

    Assessment of impacts of improving energy efficiency on indoor environmental quality and public health in Europe: The INSULAtE protocol

    Haverinen-Shaughnessy, U., Turunen, M., Leivo, V., Prasauskas, T., Aaltonen, A. & Martuzevicius, D., 2012, 10th International Conference on Healthy Buildings 2012; 8-12 July, 2012, Brisbane, Australia. International Society of Indoor Air Quality and Climate , p. 1735-1736 2 p. (Healthy Buildings Conference; vol. 2).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  31. Published

    A study on the behaviour of the weathered crust in the Perniö failure test

    D'Ignazio, M., Di Buo, B. & Länsivaara, T., 2015, Proceedings of the XVI ECSMGE 2015: 13-17 September 2015 - Edinburgh, Geotechnical Engineering for Infrastructure and Development. ICE Publishing, p. 3639-3644 6 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  32. Published

    Background of target reliability levels for existing structures

    Asp, O. & Laaksonen, A., 2013, IABSE Workshop, Helsinki 2013, Safety, Failures and Robustness of Large Structures, 14-15 February, 2013, Helsinki, Finland. Finland: IABSE, p. 252-259 8 p. (International Association for Bridge and Structural Engineers Workshop; vol. 100).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  33. Published

    BIM based schedule control for precast concrete supply chain

    Nissilä, J., Heikkilä, R., Romo, I., Malaska, M. & Aho, T., 2014, 31st International Symposium on Automation and Robotics in Construction and Mining, ISARC 2014 - Proceedings. University of Technology Sydney, p. 667-671 5 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  34. Published

    Building energy-efficiency interventions in North-East Europe: Effects on indoor environmental quality and public health

    Du, L., Prasauskas, T., Leivo, V., Turunen, M., Aaltonen, A., Kiviste, M., Martuzevicius, D. & Haverinen-Shaughnessy, U., 2014, Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate. International Society of Indoor Air Quality and Climate , p. 637-639 3 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  35. Published

    Calculating the need for repair of concrete facades in the Finnish climate

    Köliö, A. & Lahdensivu, J., 2011, Concrete Solutions, Proceedings of Concrete Solutions, 4th International Conference on Concrete Repair, Dresden, Germany, 26-28.9.2011. Grantham, M., Mechtcherine, V. & Schneck, U. (eds.). Boca Raton, FL: CRC Press, p. 541-546 (International Conference on Concrete Repair).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  36. Published

    Compromise decision-making for building design

    Tiainen, T., Mela, K., Heinisuo, M. & Grierson, D., 2011, European Group for Intelligent Computing in Engineering, 2011 eg-ice Workshop, University of Twente, The Netherlands, 6-8.7.2011. Hartmann, T., de Wilde, P. & Rafiq, Y. (eds.). Twente: University of Twente, p. 1-8 8 p. (European Group for Intelligent Computing in Engineering eg-ice Workshop).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  37. Published

    Durability Properties of Existing Concrete Facades

    Lahdensivu, J., 2012, fib Symposium Stockholm 2012, Concrete Structures for Sustainable Community, Proceedings, 11-14 June 2012, Stockholm, Sweden. Bager, D. H. & Silfwerbrand, J. (eds.). Betongföreningen; Swedish Concrete Association; fib; Swedish fib National Member Group, p. 255-258 (fib Symposium).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  38. Published

    Effect of Natural Convection on the Thermal Transmittance of Exterior Walls with Air-Permeable lnsulation

    Huttunen, P. & Vinha, J., 2013, Thermal Performance of Exterior Envelopes of Whole Buildings XII Conference , December 1-5, 2013, Clearwater, Florida.. ASHRAE, 7 p. (Thermal Performance of Exterior Envelopes of Whole Buildings; vol. 12).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  39. Published

    Experimental research on modular thin-walled steel structures

    Heinisuo, M., Lahdenmaa, J. & Jokinen, T., 2014, 12th International Conference on Steel Space & Composite Structures, Prague, Czech Republic, 28-30 May 2014. Wald, F. & Chiew, S-P. (eds.). Prague: Czech Technical University in Prague, p. 85-97 13 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  40. Published

    Exploring facilities management - Towards future campuses

    Rytkönen, E., Nenonen, S. & Kärnä, S., 2012, Proceedings of the 40th SEFI Annual Conference 2012 - Engineering Education 2020: Meet the Future. European Society for Engineering Education SEFI

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  41. Published

    Extent of condition assessment of concrete building-practical experiences

    Lahdensivu, J. & Varjonen, S., 2011, Concrete Solutions, Proceedings of Concrete Solutions, 4th International Conference on Concrete Repair, Dresden, Germany, 26-28.9.2011. Grantham, M., Mechtcherine, V. & Schneck, U. (eds.). Boca Raton, FL: CRC Press, p. 85-90 (International Conference on Concrete Repair).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  42. Published

    Factors Affecting the Performance of Railway Track Substructures in Seasonally Cold Climates

    Nurmikolu, A. & Guthrie, W. S., 2013, ISCORD 2013: Planning for Sustainable Cold Regions - 10th International Symposium on Cold Regions Development Anchorage, Alaska, United States June 2-5, 2013. Zufelt, J. E. (ed.). American Society of Civil Engineers ASCE, p. 655-666 12 p. (International Symposium on Cold Regions Development).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  43. Published

    Freeze-thaw resistance testing of concrete railway sleepers

    Köliö, A., Rantala, T., Lahdensivu, J. & Nurmikolu, A., 2014, Concrete Solutions - Proceedings of Concrete Solutions, 5th International Conference on Concrete Repair, Belfast, Northern Ireland, 1-3 September 2014. Grantham, M., Basheer, M., Magee, B. & Soustsos, M. (eds.). London: CRC Press; Taylor & Francis Group, p. 533-539 7 p. (International Conference on Concrete Repair).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  44. Published

    Improving calculations of building energy consumption based on ten year measured data

    Kiviste, M., Lindberg, R. & Leivo, V., 2013, 12th International Scientific Conference on Engineering for Rural Development 2013, Jelgava, Latvia, 23.-24.5.2013. International Scientific Conference on Engineering for Rural Development, p. 451-455 5 p. (International Scientific Conference on Engineering for Rural Development).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  45. Published

    Integration of BIM and automation in high-rise building construction

    Heikkilä, R., Malaska, M., Törmänen, P. & Keyack, C., 2013, ISARC 2013 - 30th International Symposium on Automation and Robotics in Construction and Mining, Held in Conjunction with the 23rd World Mining Congress. p. 1171-1176 6 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  46. Published

    Measurements and Modeling of Frost Depth in Railway Tracks

    Pylkkänen, K., Nurmikolu, A., Guthrie, W. S. & Argyle, H. M., 2015, Proceedings of the International Conference on Cold Regions Engineering: 16th International Conference on Cold Regions Engineering 2015. American Society of Civil Engineers ASCE, p. 123-134 12 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  47. Published

    New mechanistic design approach for subgrade rutting of Low Volume Roads

    Kolisoja, P., Kalliainen, A. & Vuorimies, N., 2015, XVI ECSMGE 2015, 13-17 September 2015 - Edinburgh: Geotechnical engineering for infrastructure and development. p. 301-306 6 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  48. Published

    Optimization of Structural Hollow Sections

    Tiainen, T. & Heinisuo, M., 2013, Proceedings of the Fourteenth International Conference on Civil, Structural and Environmental Engineering Computing. Topping, B. H. V. & Ivanyi, P. (eds.). Stirlingshire, UK: Civil-Comp Press, 15 p. Paper 228. (Civil-Comp Proceedings; no. 102).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  49. Published

    Partial dismantling of 1960's to 80's housing estates - a sustainable holistic solution

    Huuhka, S., 2013, Structures and Architecture, Concepts, Applications and Challenges, Proceedings of the 2nd International Conference on Structures and Architecture, ICSA 2013, Guimaraes, Portugal, 24.-26.7.2013. Cruz, P. J. S. (ed.). p. 1031-1039 9 p. (International Conference on Structures and Architecture).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  50. Published

    Railway track stiffness measurements at bridge transition zones

    Luomala, H. & Nurmikolu, A., 2012, Advances in Transportation Geotechnics II. Proceedings of the 2nd International Conference on Transportation Geotechnics (2nd ICTG), Hokkaido, Japan, 10-12 September 2012. Miura, S., Ishikawa, T., Yoshida, N., Hisari, Y. & Abe, N. (eds.). London: Taylor & Francis Group, p. 811-816 (Advances in Transportation Geotechnics).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  51. Published

    Real-time in-situ Monitoring of Frost Depth, Seasonal Frost Heave, and Moisture in Railway Track Structures

    Pylkkänen, K., Luomala, H., Guthrie, W. S. & Nurmikolu, A., 2012, Cold Regions Engineering 2012, Sustainable Infrastructure Development in a Changing Cold Environment, 15th International Specialty Conference on Cold Regions Engineering August 19-22, 2012, Quebec City, Canada. Morse, B. & Doré, G. (eds.). Baltimore, MD: American Society of Civil Engineerings ASCE, p. 446-455 (Cold Regions Engineering).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  52. Published

    Shear buckling and resistance of thin-walled steel plate at non-uniform elevated temperatures

    Salminen, M. & Heinisuo, M., 2011, 10th International Conference on Steel Space and Composite Structures. CI-Premier Pte Ltd, p. 267-276 10 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  53. Published

    Special Inspections and Rehabilitation of Concrete Bridges in Finland

    Nykänen, S., Uotila, J., Äijälä, M., Laaksonen, A. & Guthrie, W. S., 2013, ISCORD 2013: Planning for Sustainable Cold Regions - 10th International Symposium on Cold Regions Development Anchorage, Alaska, United States June 2-5, 2013. Zufelt, J. E. (ed.). American Society of Civil Engineers ASCE, p. 706-717 12 p. (International Symposium on Cold Regions Development).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  54. Published

    Structural analysis of tubular truss in fire

    Diez Albero, J. A., Tiainen, T., Mela, K. & Heinisuo, M., 2015, ISTS15, 15th International Symposium on Tubular Structures, : 27-29 May 2015. CRC Press/Balkema, p. 181-187 7 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  55. Published

    Structural behaviour of long integral abutment bridges

    Laaksonen, A., 2012, Global Thinking in Structural Engineering: Recent Achievements. International Association for Bridge and Structural Engineering (IABSE)

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  56. Published

    Testing of full scale pre-stressed concrete beams

    Lindberg, R., Lindberg, N., Laaksonen, A. & Vilonen, I., 2013, IABSE Workshop, Helsinki 2013, Safety, Failures and Robustness of Large Structures, 14-15 February, 2013, Helsinki, Finland. IABSE, p. 170-176 7 p. (International Association for Bridge and Structural Engineers Workshop; vol. 100).

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
  57. Published

    The assessment of constructability: BIM cases

    Tauriainen, M., Puttonen, J., Saari, A., Laakso, P. & Forsblom, K., 2015, eWork and eBusiness in Architecture, Engineering and Construction - Proceedings of the 10th European Conference on Product and Process Modelling, ECPPM 2014. CRC Press/Balkema, p. 55-61 7 p.

    Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Scientific › peer-review

    Full text: ExLibris SFX link
Previous 1 2 3 4 Next

ID: 9700463

View graph of relations

Tampere University of Technology is at the leading edge of technology development and a sought-after collaboration partner among the scientific and business communities. The University produces competent graduates who enter careers in the different sectors of society.

Quick links

Follow us

subscribe to the TUT science newsletter Interface