Responses of mixed light-emitting diode ratios on vegetative, flower regulation, and stalk elongation of cut chrysanthemum (Dendranthema grandiflora Tzvelev)

A Greenhouse experiment on the study of responses of mixed light-emitting diode ratios in cut chrysanthemum (Dendranthema grandiflora Tzvelev) was conducted at the Department of Floriculture and Landscape Architecture, Tamil Nadu Agricultural University, Coimbatore during 2019-20. The experiment was laid out in Randomized Block Design with three replications. The treatment comprises of seven varied light-emitting diode irradiance levels viz., L1 – 100% White; L2 – 100% Red; L3 - 80% Red + 20% Blue; L4 – 80% Red + 20% Far-red; L5 – 75% Blue + 25% Far-red; L6 – 60% Red + 20% Blue + 20% Far-red; L7 - High pressure sodium vapour lamp (as check) in Salvador and Pusa Centenary varieties. The results revealed that the growth in terms of height of the chrysanthemum at critical stages was maximum (48.88 cm in Salvador and 41.92 cm in Pusa Centenary) under the light irradiance of B75FR25 (L5) during the peak vegetative stage and registered maximum leaf area. Highest internodal length up to 3rd leaf of 1.07 cm was registered in sodium vapour lamp irradiance (L7) and 1.39 cm in 100% Red irradiance (L2). The early flower bud emergence (39 days in Salvador and 50 days in Pusa Centenary) was observed in B75Fr25 spectral irradiance (L5). The highest total cut stem yield per square meter (42.65 in Salvador and 41.99 in Pusa Centenary) was registered in R80B20. The study revealed that blue LEDs combined with Far-red promoted early flowering and inhibited stem elongations. Red and Blue wavelength increased the total leaf area and registered improved flower yield.

A design methodology for acoustic resonance-free, high-frequency, dimmable electronic ballast for high-pressure sodium-vapour lamps

This paper presents a methodology to design acoustic resonance-free, high-frequency, dimmable electronic ballasts for high-pressure sodium vapour (HPSV) lamps having a range of rated wattage (70–400 W). After estimation of the ‘quiet window’ of an HPSV lamp, the proposed iterative algorithm is able to determine the acoustic resonance-free driving frequencies of a design ballast corresponding to 50%–100% power level. On the other hand, a developed wattage and voltage independent HPSV lamp model facilitates finding the required electrical characteristics of HPSV lamps without performing laboratory experimentation. Using the estimated driving frequencies of a design ballast and the synthesized electrical characteristics of the lamp, the design circuit parameters of an electronic ballast are determined. Performance evaluation of the designed ballasts, carried out on the Matlab–Simulink platform, indicates several important attributes, viz. higher power control accuracy (deviation ≤3.69%), near-unity lamp power factor (≥0.98), lower lamp current crest factor (<1.7) and lower lamp current total harmonic distortion (≤12.63%). Results establish the effectiveness of the proposed design methodology to design lightweight and compact electronic ballasts for HPSV lamps with less effort than conventional design practice.

High-temperature reaction of sodium vapour with quartz glass

Heat pipes are one of the most efficient ways to transfer thermal energy hundred times more efficiently than copper. In this work, we present the investigation of sodium terminal velocity inside a glass pulsating heat pipe. Velocity measurements were conducted under operating conditions within the range of 500 – 1 100 °C. Since sodium is generally able to etch glass and ceramic materials, its presence resulted in glass reduction and sodium oxidation. From the XPS analysis of specimens extracted from a glass pipe after sodium explosion, it can be concluded that the reaction products are sodium oxide Na2O and a thin layer of carbon, which is localized on the SiO2 glass. The character of damage induced by chemical reactions is analysed in this manuscript.

Investigation of sodium insertion into tetracyanoquinodimethane (TCNQ): results for a TCNQ thin film obtained by a surface science approach

Tetracyanoquinodimethane (TCNQ) was exposed to sodium vapour resulting in three phases containing reduced TCNQ with different electronic structures and chemical compositions.