This study aims to reveal visual factors which determine the visual palatability of food dishes. We conducted subjective experiments under different light sources, and examined the correlation between the visual palatability and the visual factors, color appearance, glossiness, and convexo-concave perception. We prepared twelve kinds of food dishes, and measured the chromaticity values of all dishes under six kinds of light sources. Next, we transformed the measured data into their respective RGB values. This color management process ensures that the digital images can be displayed with the same chromaticity values as the real objects so that participants can observe the same visual stimuli with no olfactory cues. Twenty participants observed one of the images for one minute, and evaluated the “visual palatability”, and answered subjectively three factors, “color appearance”, “glossiness” and “convexo-concave perception”. As a result, it was revealed that higher correlated color temperature light makes the dishes more palatable, suggesting that the color appearance is an important visual factor for the visual palatability of food dishes. In addition, it was shown that the visual palatability of the raw food dishes and the dishes with sauce can be affected by both color appearance and glossiness depending on the light source.
At present, there is no internationally accepted method of evaluation that converts discomfort glare in pedestrian zones into numerical form. While LED streetlights are rapidly coming into wide use, their light-emitting parts are often nonuniform in luminance compared with streetlights that employ HID lamps. This nonuniformity has been noted as a factor responsible for the emergence of glare. A subjective evaluation experiment was conducted with seven types of streetlights placed in an outdoor field that simulated a pedestrian zone. The streetlights used for the experiment were selected in consideration of the type of light source and the luminance uniformity of the light-emitting surfaces. The results showed that luminance-based photometric quantities are a better measure of discomfort glare than is the illuminance at the observer's eye for light sources with both uniform and nonuniform surfaces. Based on the experimental results, a new evaluation equation that converts discomfort glare in pedestrian zones is proposed.
This paper calculates the visible radiations of discharges sustained by a microwave (mw) electromagnetic field of a high intensity discharge (HID) lamp. A microwave Mercury (Hg) lamp is considered to be excited by microwave electromagnetic fields in a cylindrical TM010 mode. A 2.45 GHz microwave generator is going to be used to sustain a stable plasma column with discharge gases. A numerical model is used to obtain the power balance in the discharge based on a solution to the Elenbaas–Heller equation for the gas temperature, and a simple “skin depth” model to describe the penetration of the maintenance electric field in the discharge. The obtained plasma for the discharge is assumed to be at local thermodynamic equilibrium (LTE) with no diffusion. Classical spectral line broadening theory is used to provide information on the visible spectrum. However, this theory is inadequate to describe the UV and IR portion of the spectrum, so self-consistent modeling of these discharges is not possible at present and only visible radiations are considered. We show in this work that an increase in electric power does not necessarily lead to an increase in the visible radiation of mw HID lamp. The photometric curve of a pure Hg mw lamp is also calculated. The lamp volume is subdivided into meshes and a local absorption and emission coefficients is assigned to each mesh. A model based on ray tracing method is employed to simulate the radiation transport in these lamps. The line profile is obtained by the convolution of the Lorentzian and Quasi-static profiles. The output flux, luminous flux, luminous efficacy, the Correlated Color Temperature (CCT) and photometric curves of the lamp are therefore obtained.
The solar bottle bulb has become a very important source of light in poor regions and/or in those that have difficult access to power. Its extended use results in the need to have a more rational knowledge of its performance. In this work, we carried out the photometry of the solar bottle bulb considering the sky models that simulate cloudy and sunny days with the sun at different angles. The results show a performance varying from 50 to 70%, according to the position of the bottle and the characteristics of solar radiation, together with a distribution of light that greatly improves the one given by a hole in the roof, thereby reducing up to 32 times its maximum intensity.
In present paper, the natural light was led into the entrance section of a highway tunnel by the specially designed lighting bands, and the lighting luminance profile was modeled referring to the human visual adaptation curve. As the result, the lighting enhanced at the entrance section was completely canceled. In order to validate the current scheme, lighting effects were evaluated by experimental data. In contrast to the conventional schemes, this scheme presented more advantages: (1) Eliminating the ‘black-hole effect’ of tunnel entrance, which significantly improved the driving safety and amenity. (2) The energy-saving of lighting was very considerable. (3) The scheme was simple, practical, and reasonable in cost. It could be concluded the application of natural light to tunnel lighting engineering had significant popularization value.