Совершенствование технологии сооружения подводных переходов трубопроводов проложенных методом горизонтально-направленного бурения

Цель работы – разработка рекомендаций по применению технологии прокладки трубопроводов методом горизонтально-направленного бурения с применением защитного устройства. В процессе исследования проводились сравнительная характеристика существующих методов бестраншейной прокладки трубопроводов, расчет основных характеристик подводного перехода, подбор защитного устройства, исследование напряженно-деформированного состояния трубопровода с помощью конечно-элементного моделирования в программном комплексе Ansys. В результате исследования подобраны оптимальные параметры подводного перехода, методом конечно-элементного моделирования в программном комплексе Ansys определено напряженно-деформированнон состояние трубопровода с защитным устройством и без него.The purpose of the work is to develop recommendations for the application of pipeline laying technology by the method of horizontal directional drilling using a protective device. In the process of the research, the existing methods of trenchless pipeline laying, the calculation of the main characteristics of the underwater crossing, the selection of the protective device, the study of the stress-strain state of the pipeline using finite element modeling in the software complex Ansys were compared. As a result of the research, optimal parameters of the underwater transition were selected, the finite element method in the software complex Ansys determined the stress-strain state of the pipeline with the protective device and without it

Progress in microwave GaN HEMT grown by MBE on silicon and smart Cut TM engineered substrates for high power applications

SiCOI (SiC On Insulator) composite substrates obtained by the Smart-Cut TM process are alternative possible substrates for epitaxial growth of Wide Band Gap (WBG) materials such as GaN and GaN alloys. Similar to bonded SOI structure, the SiCOI structures basically comprises a thin film of single SiC crystal bonded onto a substrate such as, for instance, silicon substrate. Additionally to the well known insulation properties, SiCOI substrates have been proven to be adapted to the growth of high quality GaN layer. This first study has proven compatibility of SiCOI structure for single layer GaN MBE growth. We present here last results of AlGaN / GaN HEMT structure grown by MBE with NH3 as nitrogen precursor onto SiCOI (on silicon) structure realised by Smart Cut ™. First of all, complete SiCOI structure realisation will be described and typical physical characterization results will be presented for this kind of substrate. Then, will be detailed MBE epitaxy set-up and growth parameters for HEMT structure, including specific buffer layer stack description. Finally, physical and electrical characterisation results for epi-layers and HEMT structure will be presented. Those results show strong compatibility of SiCOI structure for MBE epitaxy of GaN based HEMT structure and demonstrate the interest of Smart Cut ™ approach to build composite substrates, like SiCOI, for hetero-epitaxy application