PSNR compares the reference image with the reconstructed image and does numerical comparison, but SSIM takes into account the biological factors of the Human Visual System (HVS) and calculates the structural similarity between them. For 1024×1024 sized CT online images, PCT and PRT gave good results compared to PWT at all bit rates. The table shows the BPP at which best PSNR is obtained for all the test images.
For other modalities, PCT and PRT perform better at lower bit rates and PWT gave good PSNR at higher bit rates. In terms of PSNR, the PWT-based compression approach performs better for CT real-time images for all sizes and for all bit rates. SSIM using test images of different sizes and modalities. This can only be done if details of the way the fan is to be used, together with details of the environment it is serving, are known and a detailed acoustic analysis is carried out.įigure 5.9. What he cannot do is unequivocally state what sound pressure levels will result from the use of the fan. However, the manufacturer can calculate this level after measuring the sound pressure levels in each octave band with the fan working in an accepted standard acoustic test rig. It is impossible to measure directly the sound power level of a fan.
He must also appreciate that dB re 10 −12 watts and dB re 2 × 10 −5 Pa are different units. Note: The engineer must clearly distinguish and understand the difference between sound power level and sound pressure level. Pneumatic chipping and riveting (operator's position)Īutomatic punch press (operator's position)
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