Knowledge of the airflow distribution inside a Tunnel Boring Machine (TBM) can create a safe working environment for workers and machinery. The airflow quality and the related mass flow rate in the ventilation system should be sufficient to dilute gases and remove dust inside the tunnel. In this work, airflow distribution in the single shield TBM tunnel was studied using computational fluid dyn...

We calculate the ionisation fraction in protostellar disk models using two different gas–phase chemical networks, and examine the effect of turbulent mixing by modelling the diffusion of chemical species vertically through the disk. The aim is to determine in which regions of the disk gas can couple to a magnetic field and sustain MHD turbulence. The disk models are conventional α–disks, and th...

Abstract A protoplanetary disk (PPD) typically forms a dead zone near its midplane at distance of few astronomical units from the central protostar. Accretion through such magnetically layered can be intrinsically unstable and has been associated with episodic outbursts in young stellar objects. We present first investigation into effects low-metallicity environment on structure zone, as well r...

We calculate the ionisation fraction in protostellar disk models using a number of different chemical reaction networks, including gas–phase and gas–grain reaction schemes. The disk models we consider are conventional α–disks, which include viscous heating and radiative cooling. The primary source of ionisation is assumed to be X–ray irradiation from the central star. For most calculations we a...