Influence Of Spectral Distribution Research Articles

Influence of spectral distribution on accommodation—vergence and reading performance

Background: To assess the influence of different spectral energy distribution on accommodation, vergence and reading performance. Methods: A Randomized experimental study was conducted after getting the approval of the Ethical Committee of University of Hyderabad. Forty participants with an age group of 18–21 years was integrated, out of which 50% was male and 50% was female. Subjects with emmetropia and no history of ocular pathology were included in the study. Near point of accommodation (NPA) & near point of convergence (NPC) was measured with the help of royal air force (RAF) ruler followed by near visual task of a readability passage. Results: A statistically significant result was obtained when reading rate, reading speed and NPC was compared among different spectral distribution of light (P Conclusions: This study concluded that reading performance (reading rate and reading speed) and NPC has a significance change if we use inappropriate lighting during visual tasks. It will cause visual fatigue and strain after sustained near work. In addition, tungsten spectral energy influences the convergence which can also show an impact on reading and near visual tasks because of its brightness and miosis. Prolonged reading and working under this lighting can cause convergence disorders and visual fatigue.

Influence of spectral distribution on bacterial inactivation and quality changes of fresh-cut watermelon treated with intense light pulses

The application of intense light pulses (ILP) is an emerging technology with interesting prospects regarding food preservation. However, information concerning the factors affecting the inactivation of microorganisms and their impact on the quality of fresh-cut fruit is scarce. In this study, the effects of spectral ranges on inactivation of Escherichia coli and Listeria innocua in fresh-cut watermelon were determined. In addition, the effect of ILP on the quality parameters of fresh-cut watermelon was evaluated. The effectiveness of ILP was significantly affected when the UV-portion of light was blocked, which resulted in lower log reductions for both microorganisms. Full-spectrum treatments with an overall fluence of 12J/cm2 reduced the E. coli populations by more than three log cycles. On the other hand, the initial loads of L. innocua were reduced by 2.79 log, demonstrating that this microorganism is less sensitive to ILP treatment than E. coli. The entire spectral range of ILP had a higher negative effect on the color, texture and headspace gas composition in comparison to treatments without UV light. This work demonstrates that a slight modification in the spectrum of ILP treatments, mainly in the UV portion, may have a negative impact on the effectiveness of the treatment.

Spectral Reflectance Patterns of Photovoltaic Modules and Their Thermal Effects

Determination of the working temperature of photovoltaic (PV) modules is an essential task in research and engineering projects. It acquires more relevance in the current environment, characterized by increasing figures of installed PV power, module efficiency, solar applications, and operational configurations. However, most of the current procedures for temperature determination of PV modules are simply based on empirical correlations, carried out at conditions defined by some specific standards, with the corresponding lack of accuracy when modules work under real conditions. Thus, the present work looks into a formal procedure for temperature determination by conducting a power balance between the dynamic incoming and outgoing power fluxes. Some additional parameters are included when compared with classic expressions. In particular, the spectral reflectance of the tandem glass-semiconductor is measured to determine the reflected fraction of solar irradiance. The relationship between reflectance and equilibrium temperature is determined for a representative group of PV modules, and the influence that the working point exerts on the module temperature has also been taken into account. Finally, the influence of spectral distribution on module temperature has been quantified by simulations carried out by using a spectral model. In this way, determination of absolute temperature is achieved within a ±2°C range, regardless of module characteristics and climatic or operational conditions. In addition, temperature differences between PV modules that work under the same external conditions can be predicted within ±0.5°C. To summarize, a thermal model suitable for different PV modules and working configurations is presented. Some new parameters are introduced in the calculus process, and the influence of the most relevant ones has been quantified. In this way, the present work is aimed at making a contribution to the study of PV module temperature.