Parameter Influence in CO2-laser/MIG Hybrid Welding
Hybrid welding, as the combination of laser beam and arc welding, is an innovative joining technology that has many advantages compared to the single processes. With the hybrid process joint gap ca ...
The mechanism of high speed leading path laser-arc combination welding
In order to fully understand the causes of high speed welding defects in Leading Path Laser-Arc Combination (LPLAC) welding, the authors observed the welding process with a high speed video camera and a long distance microscope under a variety of conditions using various arc voltage and arc current settings, and also varied the distance between the laser and arc. These experiments revealed how the arc parameters affect the interaction between the laser plasma and the arc, the effects of various arc setting combinations on both the quantity and behavior of the molten metal produced by the arc, and the ways in which the interaction between the laser and molten metal can be affected. In LPLAC welding, the behavior of the molten metal produced by the arc, and the interaction between the laser and arc are both critical factors. As the distance between the laser and arc directly affects their interaction, it must be carefully considered for each welding speed.In order to fully understand the causes of high speed welding defects in Leading Path Laser-Arc Combination (LPLAC) welding, the authors observed the welding process with a high speed video camera and a long distance microscope under a variety of conditions using various arc voltage and arc current settings, and also varied the distance between the laser and arc. These experiments revealed how the arc parameters affect the interaction between the laser plasma and the arc, the effects of various arc setting combinations on both the quantity and behavior of the molten metal produced by the arc, and the ways in which the interaction between the laser and molten metal can be affected. In LPLAC welding, the behavior of the molten metal produced by the arc, and the interaction between the laser and arc are both critical factors. As the distance between the laser and arc directly affects their interaction, it must be carefully considered for each welding speed.
Alterations in spontaneous single unit activity of striatal subdivisions during ontogenesis in mutant dystonic hamsters
The pathophysiology of idiopathic dystonia, characterized by sustained twisting movements and postures, is still unknown. Clinically, however, the basal ganglia are thought to be the main causative origin of idiopathic dystonia. In the dtsz hamster, a genetic animal model for idiopathic paroxysmal dystonia, the attacks occur in response to mild stress and the severity of dystonia is age-dependent. Previous autoradiographic studies in the dtsz hamster revealed a decreased dopamine D1 and D2 receptor binding and an increased [3H]-2-deoxyglucose uptake in the dorsomedial caudate-putamen (CPu), a region supposed to be critically involved in dystonia. Therefore, we were interested whether the spontaneous firing rate of dorsomedial striatal neurons is age-dependently altered in comparison to age-matched non-dystonic control hamsters. Extracellular recordings of spontaneous single unit activity of dorsomedial and ventromedial Type II striatal neurons, i.e., biphasic positive-negative action potentials, from fentanyl anesthetized animals revealed a drastically increased firing rate in the dorsomedial CPu of mutants during age of maximum severity of dystonia. In post-dystonic dtsz hamsters, i.e., after remission of stress-inducible dystonia, no significant differences regarding the dorsomedial CPu could be obtained. We conclude that the dorsomedial subregion of the CPu seems to be critically involved in the dystonic syndrome of dtsz hamsters and that a transiently reduced inhibitory control over excitatory cortico-striatal processes, possibly due to an altered development of GABAergic inhibition, occurs during ontogenesis in dtsz hamsters.