Global Journal of Technology and Optimization

Sonoluminescence from various types of cavitation bubbles, namely those of water jet cavitation (WJC), water jet cavitation with a swirl flow nozzle (SFN-WJC), multifunction cavitation (MFC), ultrasonic cavitation (UC), and ultrahigh-temperature and highpressure cavitation (UTPC), wasinvestigated. The sonoluminescence measurements were compared with the surface modification characteristics imparted to Cr-Mo steel. The luminescence intensity of the various types of cavitation was measured using two types of photon counting head, whose detection sensitivity depends on the wavelength range. 2 UTPC had the highest light intensity, followed by MFC, UC, SFN-WJC, and WJC. The temperature inside the bubbles from the various types of cavitation could be estimated using the black-body emission method based on Planck’s law and the emission intensity, which was corrected for the sensitivity of the detector. UTPC, which had high luminosity and could treat surfaces at high temperatures, was found to increase compressive residual stress and decrease surface roughness compared to WJC and SFN-WJC, which had low luminosity and are forms of cold working. At higher cavitation temperature, more corrosion-resistant and oxidation-resistant films form on a steel surface. The magnitude of luminescence intensity for a cavitation process corresponds to the magnitude of corrosion potential (surface potential), which indicates corrosion resistance

Balanced Scorecard (BSC) is one of the most popular performance measurement tools of the past two decades. However, many current and potential adopters of theBSC are not convinced that the technique is able to present a comprehensive picture of organisations’ performance. This commentary paper is aiming to address someof the shortcomings of the BSC in practice and provide some suggestions for its improvement. The BSC links non-financial measures with financial measures in fourareas of performance concerned with financials, internal process, customers and innovation and learning

In the case where flow passes through a straight pipe to enter a centrifugal compressor the flow is straight, uniform and has no vorticity, ie swirling motion, so the swirl angle α1 = 0° as illustrated. As the flow passes through the centrifugal impeller, the impeller forces the flow to spin faster as it gets further from the rotational axis. According to a form of Euler's fluid dynamics equation, known as the pump and turbine equation, the energy input to the fluid is proportional to the flow's local spinning velocity multiplied by the local impeller tangential velocity. In many cases, the flow leaving the centrifugal impeller is travelling near the speed of sound. It then flows through a stationary compressor causing it to decelerate. The stationary compressor is ducting with increasing flow-area where energy transformation takes place. If the flow has to be turned in a rearward direction to enter the next part of the machine, e.g. another impeller or a combustor, flow losses can be reduced by directing the flow with stationary turning vanes or individual turning pipes (pipe diffusers). As described in Bernoulli's principle, the reduction in velocity causes the pressure to rise.