An electroconvective pattern called soft-mode turbulence (SMT) of homeotropic alignment in MBBA (4’-Methoxy-benzylidene-4-butyl-aniline) nematic liquid crystal appears when an external electric field with a certain frequency applied on the nematic liquid crystal sample at a threshold voltage (V SMT). The threshold voltage will increase with increasing of frequency. SMT fluctuation occurs when V SMT continues to increase at the same frequency. This phenomenon can be analized by applying an image processing tecnique. Based on image feature extraction method, inhomogeneity of SMT patterns can be observed through contrast, correlation, energy, homogeneity, and entropy parameters. Those parameters represent a result in accordance with the image visualization. Significant changes in the value of contrast, energy, homogeneity, and entropy parameters occur at V> V SMT which fluctuation begin. In this experiment the fluctuation begin at V = 27.3 V.

In this research, we compare two samples of Liquid Crystal sheet (LCs), R30C5W and R35C5W to get information about the characteristic of LCs based on the color-play of the LCs surface caused by increasing of temperature. We analize the color-play of the samples quantitatively by image analysis using hue parameter, texture analysis method by choosing entropy and energy parameter, and color-play area measurement. According to the experiment results, both samples show the similar characteristic in color-play behaviour, illustrated by similar curve for each sample, the different only in the starting temperature of the color-play and the clearing point temperature. The samples also show the same behavior in increasing of the color-play area linearly by increasing of temperature. Based on the graph of hue, entropy and energy parameters, it can be measured the clearing-point temperature of samples at 43 °C and 49 °C for LCs R30C5W and LCs R35C5W respectively. Moreover, the changes of color from red to blue cause the irregularity of pattern illustrated by increasing of entropy values and decreasing of energy values. Study the characteristic of LCs in various types is important particularly before it is used for many application purposes, for instance in heat transfer observation.

We have experimentally studied the twist dynamics as a function of temperatures in chiral nematic liquid crystals by applying texture analysis to the image data observed by polarized light microscopy. These microscopic textures are analyzed using MATLAB software. The irregularity of texture at different temperatures observed by statistical parameter such as entropy indicate the changes of director orientation. Moreover, the changes in textural as a function of temperatures are useful to investigate the order parameter values of chiral nematic liquid crystals also to predict the behavior of twist dynamics. The order parameter values of the samples at different temperatures are obtained based on images intensity along twist-line using simple calculation then the behavior of twist dynamics are visualized. The study of dynamics of twist mode chiral nematic liquid crystals is important to observe the electro-optic effect in display technology or other applications.

A Smart material can adapt to the external influences such as pressure, temperature, humidity, pH, electric or magnetic fields, an example is liquid crystal. Liquid crystal materials also can be applied for thermal mapping such as thermochromic liquid crystals (TLC) sheet. TLC sheet has a good response to the temperature changes which is shown by color play. This special characteristic of TLC can be used to explain some theoretical aspects of heat transfer on metals. The metals surface images during heating will be processed by converting the RGB images to the HSV images and then applied an edge detection method on hue images. From the thermal visualization, it can be shown that the largest heat exchange to the environment occurs at metal edges, so it is necessary to apply the heat insulator during the process of collecting data in block calorimeter experiments. The brass metal has the highest heat transfer rate, followed by copper and brass. It corresponds to the specific heat (c) of metals whichcsteel>ccopper>cbrass. Furthermore, it can be shown that since the heat starts to be evenly distributed until 300 seconds, the increasing of metals temperature is obtained ∆Tsteel<∆Tcopper<∆Tbrassand the increasing of mean hue (∆mean-hue) are obtained ∆mean-hue(steel)<∆mean-hue(copper)<∆mean-hue(brass). This result can be used to explain that in block calorimeter experiments, the measurement should be carried out after several minutes to obtain the even heat distribution across the entire metal surface.

No abstract