Laser beam welding setup for the coaxial combination of two laser beams to vary the intensity distribution

Deep-penetration laser beam welding is highly dynamic and affected by many parameters. Several investigations using differently sized laser spots, spot-in-spot laser systems, and multi-focus optics show that the intensity distribution is one of the most influential parameters; however, the targeted lateral and axial intensity design remains a major challenge. Therefore, a laser processing optic has been developed that coaxially combines two separate laser sources/beams with different beam characteristics and a measuring beam for optical coherence tomography (OCT). In comparison to current commercial spot-in-spot laser systems, this setup not only makes it possible to independently vary the powers of the two laser beams but also their focal planes, thus facilitating the investigation into the influence of specific energy densities along the beam axis. First investigations show that the weld penetration depth increases with increasing intensities in deeper focal positions until the reduced intensity at the sample surface, due to the deep focal position, is no longer sufficient to form a stable keyhole, causing the penetration depth to drop sharply.

Fundamental Study on Underwater Cutting of 50 mm-Thick Stainless Steel Plates Using a Fiber Laser for Nuclear Decommissioning

With nuclear power plants worldwide approaching their design lifespans, plans for decommissioning nuclear power plants are increasing, and interest in decommissioning technology is growing. Laser cutting, which is suitable for high-speed cutting in underwater environments and is amenable to remote control and automation, has attracted considerable interest. In this study, the effects of laser cutting were analyzed with respect to relevant parameters to achieve high-quality underwater laser cutting for the decommissioning of nuclear power plants. The kerf width, drag line, and roughness of the specimens during the high-power laser cutting of 50 mm-thick stainless steel in an underwater environment were analyzed based on key parameters (focal position, laser power, and cutting speed) to determine the conditions for satisfactory cutting surface quality. The results indicated that underwater laser cutting with a speed of up to 130 mm/min was possible at a focal position of 30 mm and a laser power of 9 kW; however, the best-quality cutting surface was obtained at a cutting speed of 30 mm/min.

Training Needs of Horticulture Extension Personnel in Jammu Region of J&K State, India

Effective extension work depends upon competent and well-trained extension personnel. Horticulture extension personnel (Horticulture Development Officers and Horticulture Technicians) occupy the focal position in transfer of technologies to the orchardists in Jammu and Kashmir. Given this a study entitled “Training needs of horticulture extension personnel in Jammu region of Jammu and Kashmir” was undertaken. Data was collected from 200 horticulture extension personnel (30 horticulture development officers and 170 horticulture technicians) working at gross root level in all ten districts of Jammu region. Training need important score was categories in to three categories viz. least important, important, most important by using mean ± S.D technique. The finding reveals that horticulture development officer and horticulture technicians’ categories Pests /disease identification and their control measures as most important training areas in technical skills where time and methods of planting was placed as least important. Similarly in case of communication skills demonstration technique was rated highest important training need area and script writing as least important. Motivation technique and programme planning were also categories as most important training need areas of supervisory skills by horticulture development officers. Two factors viz. trainings attended and information utilization sources were significantly affecting the training needs of horticulture extension personnel.

Training Needs of Horticulture Extension Personnel in Jammu Region of J&K State, India

Effective extension work depends upon competent and well-trained extension personnel. Horticulture extension personnel (Horticulture Development Officers and Horticulture Technicians) occupy the focal position in transfer of technologies to the orchardists in Jammu and Kashmir. Given this a study entitled “Training needs of horticulture extension personnel in Jammu region of Jammu and Kashmir” was undertaken. Data was collected from 200 horticulture extension personnel (30 horticulture development officers and 170 horticulture technicians) working at gross root level in all ten districts of Jammu region. Training need important score was categories in to three categories viz. least important, important, most important by using mean ± S.D technique. The finding reveals that horticulture development officer and horticulture technicians’ categories Pests /disease identification and their control measures as most important training areas in technical skills where time and methods of planting was placed as least important. Similarly in case of communication skills demonstration technique was rated highest important training need area and script writing as least important. Motivation technique and programme planning were also categories as most important training need areas of supervisory skills by horticulture development officers. Two factors viz. trainings attended and information utilization sources were significantly affecting the training needs of horticulture extension personnel.

Effect of focal position on cut surface quality in laser cutting of 50-mm thick stainless steel

In this study, the parameters for underwater laser cutting of 50-mm thick stainless steel, which is typically used in nuclear power structures, are investigated. The focal position of laser beam significantly affects the cutting quality. In particular, in the cutting of the thick sample, change in the focal position determines the kerf width and the roughness of the cut surface. Moreover, the effects of the variation of kerf width and the cut surface characteristics on the focal position of the laser beam are investigated. As the focal position moved to the inside of the material, the upper kerf width increased, but the quality of the cut surface was improved.