All publications Technical Brochures Session Materials Webinars Symposia Green Books Electra CIGRE Science & Engineering Reference Papers Working Group Reports Colloquia National Committees Journals CIGRE History books ISH Collection Search See all publications and filters Search by hot topic Search by hot topic Digitalisation Solar PV and Wind Storage Hydrogen Grids and Flexibility Consumers, Prosumers and Electric Vehicles Sustainability and Climate Sector Integration See the breadcrumb Home Publications Search results Search results Filters Publications Session Materials 10048 Electra 1590 Technical Brochures 974 ISH Collection 787 Webinars 63 Colloquia 57 Symposia 44 CIGRE Science & Engineering 37 Working Group Reports 27 Green Books 21 Reference Papers 19 CIGRE History books 4 National Committees Journals 4 Themes / Study committees Power Generation and Electromechanical Energy Conversion (A1) 611 Power transformers and reactors (A2) 806 Transmission & distribution equipment (A3) 775 Insulated cables (B1) 823 Overhead lines (B2) 867 Substations and electrical installations (B3) 796 DC systems and power electronics (B4) 851 Protection and automation (B5) 801 Power system development and economics (C1) 825 Power system operation and control (C2) 762 Power System Sustainability and Environmental Performance (C3) 262 Power system technical performance (C4) 1547 Electricity markets and regulation (C5) 418 Active distribution systems and distributed energy resources (C6) 499 Materials and emerging test techniques (D1) 725 Information Systems, Telecommunications and Cybersecurity (D2) 633 Hot topics Sustainability and Climate 44 Grids and Flexibility 32 Solar PV and Wind 27 Digitalisation 22 Storage 17 Consumers, Prosumers and Electric Vehicles 10 Hydrogen 3 Sector Integration 2 Publication year Single year Range Advanced You can find publications since 1939. Year Please enter a valid year, e.g. 2021 From Please enter a valid year, e.g. 2021 To Please enter a valid year, e.g. 2021 Query Please enter a valid query like 2015, 2018-2020, 2023 Additional media Video 160 Working groups workingGroup Search working groups 01.32 13.02 15.02 15.03 21.02 23.03 33.03.03 33.06.01 A1.16 A2.37 A2.38 A3.22 AG B4.04 AG C6.01 AG C6.17 AG D2.02 Ad Hoc WG B1.29 B1.37 B1.43 B2.49 B3.17 B3.26 B3.32 B4.46 B4.49 B4.56 B5.12 C4.111 C5.15 CEI/IEC CIGRE D1.03 D1.33 D1.37 D1.40 GT 39.05 GT/WG 07 IEEE/CIGRE JAG D1.02 JAG D1.02/TC JTF 15.02/15.05.01 JTF 15/33.03.05 JTF 21/15 JTF 23/12/13/21/22.16 JTF B4.04/A2.01 JTF D1.02/A2.11 JTF IEEE/CIGRE JWG 11/14.09 JWG 12/14.10 JWG 12/14.10.01 JWG 12/15.13 JWG 13/14.08 JWG 14.03/36.05 JWG 14/37/38/39.24 JWG 15/33.06 JWG 15/33.08 JWG 21/22.01 JWG 21/33 JWG 23/12/13/21/22.16 JWG 23/21/33.15 JWG 23/39 JWG 23/39.14 JWG 33/13.09 JWG 33/14.05 JWG 33/21/14.16 JWG 33/23.12 JWG 34/35 JWG 34/35.05 JWG 34/35.11 JWG 36.01/21 JWG 36.05.02/14.03.03 JWG 36/21.01 JWG 37/38/39 JWG 39/11 JWG A1/C4.66 JWG A2/A3/B3.21 JWG A2/B4.28 JWG A2/C4.39 JWG A2/C4.52 JWG A2/D1.41 JWG A2/D1.46 JWG A2/D1.51 JWG A3.32/CIRED JWG A3/B4.34 JWG A3/B5/C4.37 JWG B1/B3.33 JWG B1/B3.49 JWG B1/B3.74 JWG B1/B3/D1.79 JWG B1/D1.75 JWG B2/B3.27 JWG B2/B4/C1.17 JWG B2/C1.9 JWG B3.35/CIRED JWG B3/A3.59 JWG B3/B1.09 JWG B3/B1.27 JWG B3/C1/C2.14 JWG B3/C2.14 JWG B4.82/IEEE JWG B4.O4/A2.1 JWG B4/A3.80 JWG B4/A3/B3.43 JWG B4/B5.59 JWG B4/C1.65 JWG B5/C6.26/CIRED JWG B5/D2.46 JWG B5/D2.67 JWG C1/C4.36 JWG C1/C6.37/CIRED JWG C2/B4.38 JWG C2/C4.37 JWG C2/C4.41 JWG C2/C5.05 JWG C2/C5.06 JWG C2/C6.36 JWG C2/D2.41 JWG C3/37.36 JWG C3/B1/B2.13 JWG C4.2.02 JWG C4.202 JWG C4.24/CIRED JWG C4.4.02 JWG C4/A3.53 JWG C4/B4.38 JWG C4/B4.52 JWG C4/B4/C1.604 JWG C4/B5.41 JWG C4/C2.58/IEEE JWG C4/C6.29 JWG C4/C6.35/CIRED JWG C5/C1.35 JWG C5/C1.36 JWG C6/B4.37 JWG C6/B5.25/CIRED JWG C6/C1.33 JWG C6/D2.32 JWG D1/A2.47 JWG D1/B1.20 JWG D1/B1.49 JWG D1/B3.57 JWG D2/B2.39 JWG D2/B3/C2.01 JWG D2/C2.41 JWG D2/C2.48 JWG D2/C6.47 SC 12 SC 12/13/14/15/21/23/37 SC 13 SC 14/33 SC 15 SC 16 SC 21 SC 22 SC 22/IEEE SC 23 SC 23/33 SC 23/36 SC 31/32 SC 33 SC 33.01 SC A3 SC B2 SC C3 SC C4 SC C6 SC D1 TF 06.03 TF 13.00.1 TF 13.00.2 TF 14.01.01 TF 14.01.04 TF 14.01.1 TF 15.01.01 TF 15.01.03 TF 15.01.07 TF 15.01.09 TF 15.02.03 TF 15.02.04 TF 15.05.02 TF 15.06.01 TF 15.06.05 TF 22.03.01 TF 22.06.01 TF 22.11.01 TF 22.11.02 TF 22.11.03 TF 22.11.04 TF 23.02.01 TF 23.10.01 TF 23.10.03 TF 23/12/13/22/39 TF 33.01.01 TF 33.01.02 TF 33.03.05 TF 33.03.2 TF 33.04.01 TF 33.04.02 TF 33.04.03 TF 33.04.07 TF 33.04.09 TF 33.07.01 TF 33.07.02 TF 33.07.03 TF 33.07.09 TF 33.11.03 TF 33.11.06 TF 35.05 TF 35.13.02 TF 35.13.03 TF 38.01.02 TF 38.01.03 TF 38.01.08 TF 38.01.10 TF 38.01.11 TF 38.02.02 TF 38.02.03 TF 38.02.04 TF 38.02.05 TF 38.02.07 TF 38.02.14 TF 38.02.16 TF 38.02.17 TF 38.02.19 TF 38.03.01 TF 38.03.11 TF 38.03.12 TF 38.04.03 TF 38.04.04 TF 38.05.07 TF 38.05.08 TF 38.05.09 TF 38.05.10 TF 38.05.12 TF 38.06.01 TF 38.06.02 TF 38.06.06 TF A2.31 TF A3.01 TF B1.10 TF B1.26 TF B1.93 TF B2.06.09 TF B2.08.01 TF B2.11.03 TF B2.11.04 TF B2.11.05 TF B2.11.06 TF B2.11.07 TF B2.11.1 TF B2.11.O6 TF B2.12.03 TF B3.01.04 TF B3.02.01 TF B3.05.06 TF B5.03 TF B5.05 TF C2.02.24 TF C4.02.25 TF C4.102 TF C4.205 TF C4.602 TF C6.04 TF C6.04.01 TF D1.01.02.08 TF D1.01.06 TF D1.01.09 TF D1.01.10 TF D1.02.05 TF D1.02.08 TF D1.03.10 TF D1.11.04 TF D1.12.1 TF D1.16.03 TF D2.08 TF D2.10 TF D2.13 WC A1.38 WG 01 WG 02 WG 03 WG 04 WG 11.01 WG 11.02 WG 11.03 WG 11.04 WG 11.05 WG 11.06 WG 12.01 WG 12.03 WG 12.04 WG 12.05 WG 12.06 WG 12.09 WG 12.11 WG 12.12 WG 12.15 WG 12.17 WG 12.19 WG 12.22 WG 12/18.13 WG 13.01 WG 13.02 WG 13.03 WG 13.04 WG 13.05 WG 13.06 WG 13.07 WG 13.08 WG 13.09 WG 13.10 WG 13.CC.03 WG 13/14.08 WG 14.01.02 WG 14.01.03 WG 14.02 WG 14.03 WG 14.03.02 WG 14.04 WG 14.05 WG 14.07 WG 14.11 WG 14.12 WG 14.17 WG 14.18 WG 14.19 WG 14.20 WG 14.23 WG 14.25 WG 14.26 WG 14.27 WG 14.28 WG 14.29 WG 14.30 WG 14.31 WG 14.32 WG 15.01 WG 15.01.02 WG 15.02 WG 15.03 WG 15.04 WG 15.05 WG 15.07 WG 15.09 WG 15.10 WG 21.01 WG 21.02 WG 21.03 WG 21.04 WG 21.05 WG 21.06 WG 21.07 WG 21.08 WG 21.09 WG 21.10 WG 21.11 WG 21.12 WG 21.14 WG 21.16 WG 21.17 WG 22.01 WG 22.03 WG 22.04 WG 22.05 WG 22.06 WG 22.07 WG 22.08 WG 22.09 WG 22.10 WG 22.11 WG 22.12 WG 22.13 WG 22.14 WG 22.15 WG 23.01 WG 23.02 WG 23.03 WG 23.04 WG 23.05 WG 23.06 WG 23.07 WG 23.08 WG 23.10 WG 23.10.01 WG 23.11 WG 3.4 WG 31.01 WG 31.02 WG 31/32.03 WG 32.01 WG 32.03 WG 32.D2 WG 33 WG 33.01 WG 33.01.02 WG 33.01.03 WG 33.02 WG 33.03 WG 33.04 WG 33.04.04 WG 33.05 WG 33.06 WG 33.07 WG 33.10 WG 33.11 WG 34.01 WG 34.02 WG 34.03 WG 34.04 WG 34.05 WG 34.06 WG 34.08 WG 34.09 WG 34.10 WG 35. 07 WG 35.01 WG 35.02 WG 35.03 WG 35.04 WG 35.05 WG 35.06 WG 35.07 WG 35.08 WG 35.09 WG 35.13 WG 36.01 WG 36.02 WG 36.03 WG 36.04 WG 36.05 WG 36.05/CIRED WG 36.06 WG 37.01 WG 37.03 WG 37.07 WG 37.08 WG 37.09 WG 37.10 WG 37.13 WG 37.23 WG 37.27 WG 37.28 WG 37.30 WG 38.01 WG 38.01.05 WG 38.01.06 WG 38.01.07 WG 38.02 WG 38.02.08 WG 38.02.09 WG 38.02.10 WG 38.02.11 WG 38.02.12 WG 38.02.13 WG 38.03 WG 38.03.10 WG 38.04 WG 38.04.01 WG 38.04.02 WG 38.04.03 WG 38.05.04 WG 38.06.04 WG 39. 01 WG 39.01 WG 39.03 WG 39.04 WG 39.05 WG 39.06 WG A1.01 WG A1.01.03 WG A1.01.04 WG A1.01.06 WG A1.02 WG A1.04 WG A1.05 WG A1.06 WG A1.06.01 WG A1.07 WG A1.08 WG A1.09 WG A1.10 WG A1.11 WG A1.12 WG A1.13 WG A1.14 WG A1.15 WG A1.16 WG A1.17 WG A1.18 WG A1.19 WG A1.21 WG A1.22 WG A1.23 WG A1.25 WG A1.26 WG A1.27 WG A1.28 WG A1.29 WG A1.30 WG A1.31 WG A1.33 WG A1.34 WG A1.35 WG A1.36 WG A1.37 WG A1.38 WG A1.39 WG A1.40 WG A1.41 WG A1.44 WG A1.46 WG A1.47 WG A1.48 WG A1.49 WG A1.50 WG A1.54 WG A1.59 WG A1.70 WG A2.18 WG A2.20 WG A2.23 WG A2.24 WG A2.26 WG A2.27 WG A2.30 WG A2.32 WG A2.33 WG A2.34 WG A2.35 WG A2.36 WG A2.37 WG A2.40 WG A2.42 WG A2.43 WG A2.44 WG A2.45 WG A2.48 WG A2.49 WG A2.53 WG A2.54 WG A2.55 WG A2.57 WG A2.59 WG A2.62 WG A2.64 WG A2.69 WG A3.06 WG A3.07 WG A3.10 WG A3.11 WG A3.12 WG A3.13 WG A3.16 WG A3.17 WG A3.18 WG A3.19 WG A3.20 WG A3.21 WG A3.22 WG A3.23 WG A3.24 WG A3.25 WG A3.26 WG A3.27 WG A3.28 WG A3.29 WG A3.30 WG A3.31 WG A3.33 WG A3.35 WG A3.36 WG A3.38 WG A3.40 WG A3.41 WG A3.43 WG A3.48 WG AG A2.4 WG B.33 WG B1.02 WG B1.03 WG B1.04 WG B1.05 WG B1.06 WG B1.07 WG B1.08 WG B1.09 WG B1.10 WG B1.11 WG B1.16 WG B1.18 WG B1.19 WG B1.20 WG B1.21 WG B1.22 WG B1.23 WG B1.24 WG B1.25 WG B1.26 WG B1.27 WG B1.28 WG B1.29 WG B1.30 WG B1.31 WG B1.32 WG B1.34 WG B1.35 WG B1.36 WG B1.37 WG B1.38 WG B1.40 WG B1.41 WG B1.42 WG B1.43 WG B1.44 WG B1.45 WG B1.46 WG B1.47 WG B1.48 WG B1.50 WG B1.51 WG B1.52 WG B1.54 WG B1.55 WG B1.56 WG B1.57 WG B1.58 WG B1.60 WG B1.61 WG B1.62 WG B1.63 WG B1.64 WG B1.65 WG B1.66 WG B1.68 WG B1.73 WG B1.87 WG B2.03 WG B2.06 WG B2.07 WG B2.08 WG B2.11 WG B2.12 WG B2.13 WG B2.15 WG B2.16 WG B2.20 WG B2.21 WG B2.22 WG B2.23 WG B2.24 WG B2.25 WG B2.26 WG B2.28 WG B2.29 WG B2.30 WG B2.31 WG B2.32 WG B2.33 WG B2.36 WG B2.39 WG B2.41 WG B2.42 WG B2.43 WG B2.44 WG B2.45 WG B2.47 WG B2.48 WG B2.49 WG B2.50 WG B2.51 WG B2.52 WG B2.53 WG B2.54 WG B2.55 WG B2.56 WG B2.57 WG B2.58 WG B2.59 WG B2.61 WG B2.62 WG B2.63 WG B2.64 WG B2.68 WG B2.69 WG B2.81 WG B2.O6 WG B2/B3.27 WG B2/C1.19 WG B2/D2.18 WG B3.01 WG B3.03 WG B3.05 WG B3.06 WG B3.08 WG B3.10 WG B3.11 WG B3.12 WG B3.15 WG B3.17 WG B3.18 WG B3.20 WG B3.21 WG B3.22 WG B3.23 WG B3.24 WG B3.25 WG B3.26 WG B3.29 WG B3.30 WG B3.31 WG B3.34 WG B3.36 WG B3.37 WG B3.38 WG B3.39 WG B3.40 WG B3.41 WG B3.42 WG B3.43 WG B3.44 WG B3.45 WG B3.46 WG B3.47 WG B3.48 WG B3.49 WG B3.50 WG B3.51 WG B3.53 WG B3.55 WG B3.57 WG B3.58 WG B3/B1.27 WG B3/C1/C2.14 WG B4.04 WG B4.05 WG B4.19 WG B4.28 WG B4.33 WG B4.34 WG B4.35 WG B4.37 WG B4.38 WG B4.39 WG B4.40 WG B4.41 WG B4.44 WG B4.45 WG B4.47 WG B4.48 WG B4.49 WG B4.51 WG B4.52 WG B4.53 WG B4.54 WG B4.55 WG B4.56 WG B4.57 WG B4.58 WG B4.60 WG B4.61 WG B4.62 WG B4.63 WG B4.66 WG B4.67 WG B4.68 WG B4.70 WG B4.72 WG B4.74 WG B4.75 WG B4.76 WG B4.78 WG B4.79 WG B4.81 WG B4.83 WG B4.84 WG B4.85 WG B4/C3/B2.50 WG B5, WG C6.26, CIRED WG B5.01 WG B5.03 WG B5.04 WG B5.05 WG B5.06 WG B5.07 WG B5.08 WG B5.09 WG B5.10 WG B5.11 WG B5.12 WG B5.13 WG B5.14 WG B5.15 WG B5.16 WG B5.17 WG B5.18 WG B5.19 WG B5.20 WG B5.22 WG B5.23 WG B5.24 WG B5.27 WG B5.31 WG B5.32 WG B5.34 WG B5.36 WG B5.37 WG B5.38 WG B5.39 WG B5.40 WG B5.41 WG B5.42 WG B5.43 WG B5.45 WG B5.47 WG B5.48 WG B5.50 WG B5.52 WG B5.53 WG B5.54 WG B5.60 WG B5.62 WG B5.64 WG B5.66 WG B5.69 WG B5.94 WG B5.O1 WG B5/B4.25 WG B5/C1/C2/C4/C6/D2 WG C1 WG C1.04 WG C1.1 WG C1.11 WG C1.13 WG C1.14 WG C1.15 WG C1.16 WG C1.17 WG C1.19 WG C1.2 WG C1.22 WG C1.23 WG C1.24 WG C1.25 WG C1.26 WG C1.27 WG C1.29 WG C1.3 WG C1.30 WG C1.31 WG C1.32 WG C1.34 WG C1.35 WG C1.38 WG C1.39 WG C1.40 WG C1.41 WG C1.43 WG C1.44 WG C1.48 WG C1.6 WG C1.7 WG C1.8 WG C1.9 WG C1/C2/C6.18 WG C2.01 WG C2.11 WG C2.13 WG C2.16 WG C2.17 WG C2.18 WG C2.21 WG C2.23 WG C2.24 WG C2.25 WG C2.26 WG C2.33 WG C2.34 WG C2.35 WG C2.39 WG C2.40 WG C2.42 WG C2/C5.05 WG C3.01 WG C3.02 WG C3.03 WG C3.04 WG C3.05 WG C3.06 WG C3.08 WG C3.09 WG C3.10 WG C3.15 WG C3.16 WG C3.19 WG C4.01 WG C4.02 WG C4.02.25 WG C4.07 WG C4.107 WG C4.108 WG C4.109 WG C4.110 WG C4.111 WG C4.112 WG C4.2.02 WG C4.203 WG C4.204 WG C4.206 WG C4.207 WG C4.208 WG C4.23 WG C4.25 WG C4.26 WG C4.27 WG C4.28 WG C4.30 WG C4.301 WG C4.302 WG C4.303 WG C4.306 WG C4.307 WG C4.31 WG C4.32 WG C4.33 WG C4.34 WG C4.37 WG C4.39 WG C4.402 WG C4.403 WG C4.404 WG C4.405 WG C4.406 WG C4.407 WG C4.408 WG C4.409 WG C4.410 WG C4.45 WG C4.46 WG C4.47 WG C4.49 WG C4.501 WG C4.502 WG C4.503 WG C4.56 WG C4.601 WG C4.603 WG C4.605 WG C4.61 WG C5.03 WG C5.06 WG C5.10 WG C5.11 WG C5.12 WG C5.13 WG C5.15 WG C5.16 WG C5.17 WG C5.18 WG C5.19 WG C5.20 WG C5.21 WG C5.22 WG C5.23 WG C5.24 WG C5.25 WG C5.26 WG C5.27 WG C5.28 WG C5.30 WG C5.32 WG C5.33 WG C5.4 WG C5.6 WG C5.7 WG C5.71 WG C6.01 WG C6.02 WG C6.03 WG C6.04 WG C6.08 WG C6.09 WG C6.10 WG C6.11 WG C6.15 WG C6.19 WG C6.20 WG C6.21 WG C6.22 WG C6.24 WG C6.27 WG C6.28 WG C6.30 WG C6.31 WG C6.36 WG C6.38 WG C6.40 WG C6.43 WG CC.01 WG D1.01 WG D1.03 WG D1.11 WG D1.12 WG D1.14 WG D1.15 WG D1.17 WG D1.23 WG D1.24 WG D1.25 WG D1.26 WG D1.27 WG D1.28 WG D1.29 WG D1.30 WG D1.32 WG D1.33 WG D1.34 WG D1.35 WG D1.37 WG D1.38 WG D1.39 WG D1.40 WG D1.42 WG D1.43 WG D1.44 WG D1.45 WG D1.48 WG D1.50 WG D1.51 WG D1.52 WG D1.53 WG D1.54 WG D1.56 WG D1.58 WG D1.59 WG D1.64 WG D1.65 WG D1.66 WG D1.67 WG D1.70 WG D1.70 TF3 WG D1.71 WG D2.01 WG D2.07 WG D2.09 WG D2.12 WG D2.13 WG D2.14 WG D2.15 WG D2.16 WG D2.17 WG D2.18 WG D2.21 WG D2.22 WG D2.23 WG D2.24 WG D2.26 WG D2.28 WG D2.29 WG D2.31 WG D2.33 WG D2.34 WG D2.35 WG D2.36 WG D2.38 WG D2.40 WG D2.43 WG D2.45 WG D2.46 WG D2.50 WG D2/B5.30 WG. 13.03 13679 results for your search Sort by Relevance Publication date Filters Technical Brochures Advanced analytical tools in evaluating power system dynamic and security performance: Results of a questionnaire Ref 028 • 1987 Electra Operational Monitoring of Air-Cooled Hydro-Generators Ref ELT_115_1 • 1987 Electra The calculation of continuous rating for forced cooled high pressure oil filled pipe type cables Ref ELT_113_6 • 1987 Electra Transient ground potential rises in gas insulated substations with respect to earthing systems Ref ELT_110_2 • 1987 Electra Generator circuit-breaker transient recovery voltage in most severe short-circuit conditions Ref ELT_113_3 • 1987 Electra Requirements for switching tests of metal enclosed switchgear Ref ELT_110_1 • 1987 Electra Interruption of small inductive currents. Chapter 4 : Reactor switching. Part B : Limitation of overvoltages and testing Ref ELT_113_4 • 1987 Electra Test electrodes for assessing the electric strength of insulating gases Ref ELT_113_5 • 1987 Electra Influence of atmospheric conditions on the dielectric strength of external insulation Ref ELT_112_6 • 1987 Electra Discharges in long air gaps at Les Renardières - Double impulse tests Ref ELT_111_2 • 1987 Electra Results of an international survey of the rules limiting interference coupled into metallic pipelines in high voltage power systems Ref ELT_110_3 • 1987 Electra Planning against voltage collapse Ref ELT_111_5 • 1987 Technical Brochures Compendium of HVDC schemes throughout the world Ref 003 • 1987 Electra Evaluation of characteristics and performances of power system protection Ref ELT_111_3 • 1987 Electra Interaction between phases in three phase reactor switching. Part II : Ungrounded reactors Ref ELT_112_5 • 1987 Electra A note on strategy of restoration Ref ELT_114_2 • 1987 Technical Brochures Power system reliability analysis - Application guide: Part I Ref 026 • 1987 Electra Vibrations of hydro electric generating sets caused by hydraulic phenomena Ref ELT_112_4 • 1987 Electra Report on diagnosis and monitoring for evaluating the condition of windings of rotating electrical machines Ref ELT_112_1 • 1987 Electra Use of equipment built-in automatic testing - self checking and monitoring with a view to improving reliability Ref ELT_111_4 • 1987 Electra The reliability of HV substations with special regard to the secondary equipment Ref ELT_111_1 • 1987 Electra Reliability criteria used in various countries. Summary of the papers presented to the meeting of SC37 in Oslo (June 1983) Ref ELT_110_5 • 1987 Electra Power system planning : sensitivity studies from a dynamic point of view. Outline of major results of Planning Exercise No.4 Ref ELT_110_4 • 1987 Electra Some aspects of computer loading problems in modern control centres Ref ELT_114_3 • 1987 Electra The advances of high Temperature superconductors and their impact on the application of superconductivity in the electric industry Ref ELT_114_1 • 1987 Previous 1 … 464 465 466 467 468 … 548 Next