Thermal insulation of wet shielded metal arc welds
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Sciences & Engineering, 1994.
Characterization of the underwater welding arc bubble through a visual sensing method
Abstract To evaluate the effectiveness of arc bubble, the influences of controllable arc bubble on the process stability and microstructural evolution of welded joint under different welding conditions were investigated. The main welding conditions, including onshore welding, conventional underwater wet welding (UWW) and mechanical constraint assisted UWW (MC-UWW), were characterized and compared. The exerted mechanical constraint resists the arc bubble detachment and keeps the larger arc bubble attached to the weld pool surface for providing better protective effect of welding region. The adverse effect of surrounding water with its higher heat conduction is not negligible compared with onshore welding, and the mechanical coupling between arc bubble and constraint device plays a vital role in affecting the arc stability and joint quality. Microstructure analyses revealed that under the same welding parameters, the proportion of brittle microstructure in weld metal follows the order: UWW > MC-UWW > onshore welding. A more stable wet welding process can be realized by controlling the arc bubble detachment, which provides a new orientation for wet welding technique application.
An intelligent control system for ventilators.
This study reports on a ventilator system that consists of several intelligent modules for controlling ventilator operation. These modules are software programs in two controllers. One controller is a personal computer used for diagnoses, determining settings and checking the effects of settings. The other controller is a single-chip microprocessor in a ventilator that controls the ventilator's settings in accordance with the computer settings. After setting up the system, an artificial lung model simulating a patient's lung is used to test the system. The result of test run indicated that it always responds to a patient's lung condition in a stable manner. Thus, the proposed system with its intelligent modules may assist clinicians in caring for patients and managing ventilator operation.