Search

ABSTRACTIn multi-robot cooperative wire and arc additive manufacturing (MRC-WAAM) systems, allocating and scheduling deposition tasks is necessary. The challenge comes from the factorial computational complexity when optimising robot time, workload, and deposition order. This work presents a novel method, ‘top k%’. The main idea is to iteratively assign k% amount of paths from a warehouse to the robot having the least workload until all paths are set. A collision-free deposition process is scheduled by checking the overlapping conditions of robot swap areas. Both simulative testing and actual depositions were conducted to validate the applicability and effectiveness of the method. The results indicated that the ‘top k%’ method can facilitate the equality of robot workload and enhance the adjacency of paths. The top k% method outperforms the existing solutions concerning a reduction of turns and start-arc points, which improves the forming quality of MRC-WAAM.

A geothermal field is located in deep-seated basement aquifers in the northeastern part of the North China Plain near Tianjin, China. Carbonate rocks of Ordovician and Middle and Upper Proterozoic age on the Cangxian Uplift are capable of yielding 960 to 4200 [m.sup.3]/d of 57°C to 96°C water to wells from a depth of more than 1000 m. A three-dimensional nonisothermal numerical model was used to simulate and predict the spatial and temporal evolution of pressure and temperature in the geothermal system. The density of the geothermal water, which appears in the governing equations, can be expressed as a linear function of pressure, temperature, and total dissolved solids. A term describing the exchange of heat between water and rock is incorporated in the governing heat transport equation. Conductive heat flow from surrounding formations can be considered among the boundary conditions. Recent data of geothermal water production from the system were used for a first calibration of the numerical model. The calibrated model was used to predict the future changes in pressure and temperature of the geothermal water caused by two pumping schemes. The modeling results indicate that both pressure and temperature have a tendency to decrease with time and pumping. The current withdrawal rates and a pumping period of five months followed by a shut-off period of seven months are helpful in minimizing the degradation of the geothermal resource potential in the area., Zhou Xun (1) Chen Mingyou (1) Zhao Weiming (2) Li Minglang (2) Introduction Geothermal water with temperatures ranging from 57°C to 96°C occurs in the basement carbonate aquifer system of [...]

A preliminary experimental study on "warm ultrasonic impact-assisted laser metal deposition" (WUI-LMD) is reported, and such a study is rare in literature to the authors' knowledge. In WUI-LMD, an ultrasonic impact treatment (UIT) tip is placed near the laser spot for in-situ treatment of laser-deposited warm solid material, and the UIT and LMD processes proceed simultaneously. Under the conditions investigated, it is found that in-situ UIT during WUI-LMD can be much more effective in reducing porosity than a post-process UIT. Possible underlying mechanisms are analyzed. WUI-LMD has great potential to reduce defects and improve mechanical properties without increasing manufacturing time. [ABSTRACT FROM AUTHOR]