A General Method to Compute the Electric Flux Lines between Two Magnet Wires in Close Contact and Its Application for the Evaluation of Partial Discharge Risks in the Slots of Electric Machines Embedded in Future Transportation Systems

The sizing of the Electrical Insulation System (EIS) is an important challenge in electric motors of higher specific power driven by faster inverters. That keeps increasing the electric stress which the winding is submitted in the stator slot. Consequently, Partial Discharges (PD) are more likely to occur. Nowadays, the Paschen’s criterion is widely used to evaluate the risk of partial discharge. It requires the knowledge of electric field lines. This paper presents a method to precisely compute the electric field lines in a two-dimensional (2D) electrostatic problem. The field of study is composed of two magnet wires in close contact. Such configuration is representative of the turn-to-turn interaction in an electric motor slot. The problem is solved using the scalar potential formulation only. The notion of flux tubes is used for the post process of the electric field lines in a developed numerical code on Matlab. The developed method is compared to a ballistic method already included on Matlab. The work presented here is included in an automatic tool to suppress or reduce the partial discharge risk in a stator slot of high power density motor destined for future transportation systems.

Effect of ballistic electrons on ultrafast thermomechanical responses of a thin metal film

The ultrafast thermomechanical coupling problem in a thin gold film irradiated by ultrashort laser pulses with different electron ballistic depths is investigated via the ultrafast thermoelasticity model. The solution of the problem is obtained by solving finite element governing equations. The comparison between the results of ultrafast thermomechanical coupling responses with different electron ballistic depths is made to show the ballistic electron effect. It is found that the ballistic electrons have a significant influence on the ultrafast thermomechanical coupling behaviors of the gold thin film and the best laser micromachining results can be achieved by choosing the specific laser technology（large or small ballistic range）.In addition, the influence of simplification of the ultrashort laser pulse source on the results is studied, and it is found that the simplification has a great influence on the thermomechanical responses, which implies that care should be taken when the simplified form of the laser source term is applied as the Gaussian heat source.

Space Guns for the Moon and on the Moon

Space gun--a device for launching objects in space. It refers to rocket-free methods of output objects into orbit. Space gun is not able to deliver the object in stationary orbit around the planet, for this, it must be equipped with a rocket engine to adjust the course after launch the object. This makes it possible to replace the existing excessively expensive rocket systems with new methods of delivering payload （space gun）. Thus, the costs of scientific programs are decreasing at times, and many studies are becoming available, less risky and environmentally safer.