The density of solid water, unlike most molecules, is less than that of its liquid form. Its precise value is of use in many applications. Freezing a spherical droplet of water and analyzing the changed shape from a sphere to a sphere with a slight peak in order to find the density of ice. We find the density of ice to be at 0.90 ± 1.66 · 106 g/mL. The precision of our measurement was limited by uncertainty in the angle measurements of the peak of the droplet.
Watermarking technique for the image is an efficient method for protecting copyright image, and also a huge topic in cryptography. In this paper, two spread spectrum watermarking scheme, the Convolution Image-based Model (CIM) and the Exponential Convolution Image-based Model (ECIM) are going to be formulated and discussed. The watermarking experiment result will be shown and discussed, focusing on the attack scheme, protectability, and the information encryption of the watermark. We will show that the convolution image-based model for invisible watermark is weak of protectability, but it is able to hide the information (the size of watermark must be less than the original image) and store inside the image.