High-pressure Sodium Lamps Research Articles

Intelligent design of street lamp based on Arduino

In order to promote the process of social modernization, the traditional street lamps are also moving towards intelligent development. However, the existing street lamps mostly use a single LED lamp or high-pressure sodium lamp, which can’t cope with the complex road conditions in China. The designer proposes to install the monitoring system on the street lamp, design the fine artificial intelligence light distribution and color temperature regulation scheme, add the functions of positioning, alarm, repair, pollutant and rain and snow monitoring, and realize the data interaction between the street lamp and the user and the manual intervention of the user when necessary through the infrared Bluetooth Internet of things and other technologies. The design is developed, simulated, debugged and tested on Arduino hardware and software platform. The results show that the design is reasonable and feasible.

Root growth of Eleuthero (Eleutherococcus senticosus [Rupr. & Maxim.] Maxim.) seedlings cultured with chitosan oligosaccharide addition under different light spectra

Eleuthero (Eleutherococcus senticosus [Ruprecht & Maximowicz] Maximowicz is an important understory species as well as a source of natural products in Asia. The natural source of Eleuthero has been over exploited for pharmacological use, but the manual restoration to rehabilitate its natural distribution has not yet been established. The root is one of the main underground organs in Eleuthero for the acquisition of pharmaceutical ingredients. Root growth also determines the seedling quality of this species for ecological restoration. In this study, Eleuthero seedlings were cultured for one growing cycle with chitosan oligosaccharide (CO) addition at rates of 0 and 25 ppm under artificial lightings by high-pressure sodium (HPS) lamps and two light-emitting diodes (LEDs) with photosynthetic photon flux density set to 94±5 μmol m-2. Light spectra of red (R): green (G): blue (B) ratios were measured to be 43.7:54.6:1.7, 43.8:47:9.2, and 72.7:13.3:14 for the HPS, LED-1, and LED-2 treatments, respectively. In autumn, no interactive effect was found between CO addition and light spectra treatments on any root parameters. Compared to the HPS treatment, the LED-1 treatment resulted in a greater root dry weight and morphology by over 30%. The CO addition caused an increase of root growth by 40-70%. Fine roots in diameter between 0-0.4 mm were the main root part that contributed to the length, surface area, and root tip number. Therefore, LED lighting with the R/G/B spectrum of 43.8:47:9.2 was suggested for the culture of Eleuthero seedlings with the purpose of promoting dry weight and morphology of fine roots.

A Novel New Light Recipe Significantly Increases the Growth and Yield of Sweet Basil (Ocimum basilicum) Grown in a Plant Factory System

Light is a crucial element for plant growth and production. High-pressure sodium (HPS) lamps are considered not very electrically efficient as they generate high radiant heat, and as a consequence, there has been a lot of interest in replacing HPS lamps with new more efficient lighting sources in the form of light-emitting diodes (LEDs). LEDs have a linear photon output with the electrical input current, and this great feature allows the design of lighting arrays that match the plant’s needs. In the current study, light spectrum absorbance of pigments extracted from 14 plant species was analyzed. Two absorbance peaks were observed in the Photosynthetically Active Radiation (PAR) region: one at 435 nm and the other at 665 nm. The light spectrum array was designed to produce the spectrum absorbed by basil pigments. This included the use of new wavelengths of 435 ± 5 nm to cover the blue region. Moreover, the ratio between blue and red was considered to match the absorbance of basil pigment. The use of a light spectrum that matches the plant absorbance significantly improved the investigated physiological parameters and increased the growth yield of basil. Moreover, this is the first to confirm the great positive impact of using 435 nm light spectrum in comparison with the commercially widely used 450 nm LED spectrum. This investigation has great scientific and commercial applications in the field of indoor faming and plant factory systems.

Use of Combined Irradiation in Grow Light

Effective cultivation of plants with grow light is possible only under optical radiation of a certain spectral composition. The cheapest way to generate optical radiation is with the help of high pressure sodium lamps. However, their spectral composition is not fully acceptable for grow light. LEDs allow you to set almost any spectrum, but their cost is quite high. ( Research purpose ) To prove the spectral composition of the LED emitter-corrector used in grow light in addition to sodium lamps theoretically and practically. ( Materials and methods ) The authors experimentally studied the effectiveness of combined irradiation in the Laboratory of Energy Ecology of Grow Light at the Institute of Agroengineering and Environmental Problems of Agricultural Production under the irradiation of Blagovest tomato seedlings. They investigated the biometric indicators of plants. The production experiment was carried out in the greenhouse plant Mezhvidi (Latvia) on adult Encore tomato plants for three options: the first – under sodium lamps; the second – with LED irradiators; the third – with a combination of sodium lamps and corrector. The effect of the irradiator on the plants was evaluated by the magnitude of the fluctuating asymmetry of bilateral signs of the leaf blade. ( Results and discussion ) The authors found out that the use of the corrector improved the seedlings biometric parameters: increased the number of leaves, their wet weight, the content of chlorophyll and dry substance in them. It was noted that in the greenhouse the least favorable light environment was formed under sodium lamps, and LED irradiators created more comfortable conditions. They confirmed that the use of a corrector provided the best light environment. They revealed an increase in the yield of tomato fruits and their taste when using combined irradiation. ( Conclusions ) The authors proved that to correct the spectrum of HPS lamp 400, a corrector photon flux of 71.2 micromoles per second is required, while the ratio of blue and far-red LEDs fluxes should be 64 and 36 percent respectively.

Assessment of Colorimetric Parameters for HPS Lamp with Electromagnetic Control Gear and Electronic Ballast

Road lighting is an important element of road infrastructure influencing on the road safety. It helps road users to identify potential hazards on the road and reduces the risk of a road accident. Improving the energy efficacy of road lighting installations requires using new technologies. Currently, high-pressure sodium (HPS) lamps are still most commonly used in road lighting. Many of the luminaires with HPS lamps are still in good technical condition and there is no economic justification for replacing them (except improving energy efficacy). One of the methods of improving their energy efficacy is to replace the electromagnetic control gear (ECG) with an electronic ballast (EB). This replacement may affect the colorimetric parameters of the HPS lamps. Two methods to the estimation change of colorimetric parameters after the replacement of ECG to EB were used. The first is CIE TN 001:2014 and the second is ANSI/IES TM-30-15. The article also presents the advantages and disadvantages of these methods in relation to the evaluation of changes in colorimetric parameters of HPS lamps after the replacement of the ECG with an EB. After the replacement of ECG to EB, the smallest reduction of Ra (colour rendering index) occurred for the 150 W lamp by 31.30% and the highest reduction for the 70 W lamp by 65.52%. Considering the changes of the fidelity indicator Rf and gamut indicator Rg, their changes are significantly smaller than for Ra. The smallest change of Rf value was observed for a 150 W lamp (6.00%) and the largest for a 70 W lamp by 25.00%. In case of Rg, similar changes were observed—for 150 W lamp by 9.26% and for 70 W lamp by 21.88%. The ANSI/IES TM-30-15 method is more suitable for evaluating colorimetric parameters after replacing ECG with EB. Using only Ra to evaluate changes of HPS lamps colorimetric parameters after replacing the ballast type can lead to incorrect conclusions concerning changes of colorimetric parameters. Based on the ANSI/IES TM-30-15 method, it has been proposed to introduce the Δf,g indicator which determines the change of colorimetric parameters based on fidelity and gamut colour indicator.

Supplemental Radiation Quality Influences Cucumber, Tomato, and Pepper Transplant Growth and Development

Supplemental lighting is required for the production of high-quality vegetable transplants in greenhouses when the photosynthetic daily light integral (DLI) is low. Light-emitting diodes (LEDs) are a promising alternative to high-pressure sodium (HPS) lamps. However, there are a limited number of studies that have evaluated how LED supplemental lighting spectral quality beyond blue (B) and red (R) radiation influences plant growth and development. Seeds of hybrid greenhouse seedless cucumber ‘Elsie’ (Cucumis sativus), tomato ‘Climstar’ (Solanum lycopersicum), and pepper ‘Kathia’ (Capsicum annuum) were sown and placed into a dark growth chamber until radicle emergence. Seedlings were grown in a greenhouse at a 25 °C constant temperature set point and under five lighting treatments. The supplemental lighting treatments delivered a total photon flux density (TPFD) of 120 μmol·m−2·s−1 for 16 h·d−1 based on an instantaneous threshold from HPS lamps or LEDs [three treatments composed of B (400–500 nm), R (600–700 nm), white, and/or far-red (FR; 700–800 nm) LEDs], and a control that delivered 25 μmol·m−2·s−1 from HPS lamps (HPS25). The LED treatments defined by their wavebands (TPFD in μmol·m−2·s–1) of B, green (G, 500–600 nm), R, and FR radiation were B20G10R75FR15, B25R95, and B30G30R60; whereas the HPS treatments emitted B7G57R47FR9 (HPS120) and B1G13R9FR2 (HPS25). Generally, cucumber, pepper, and tomato transplants under B30G30R60 and HPS120 supplemental lighting had the greatest stem diameter. Fresh weight and leaf area of all three species was greater when G radiation replaced R or B radiation. For example, leaf area and fresh weight of cucumber, tomato, and pepper increased (by 33%, 22%, and 49%; and 35%, 14%, and 56%, respectively) for plants under B30G30R60 supplemental lighting compared with plants under B25R95 supplemental lighting. The most compact cucumber and pepper transplants were those grown under B25R95 supplemental lighting, and the most compact tomatoes were those grown under the HPS25 (control) and B25R95 supplemental lighting. Tomato transplants under treatments providing ≥30 μmol·m−2·s−1 of G radiation had an increased incidence of leaf necrosis. From this study, we conclude that plant responses to supplemental lighting quality are generally genera-specific, and therefore high-wire transplants should be separated by genera to optimize production and quality. However, additional studies are required to provide complete LED supplemental lighting recommendations.

Changes in the Biochemical Composition of Tomato Fruit under the Influence of Illumination Quality

Tomatoes are one of the most consumed vegetables in the world. Unfortunately, obtaining a high quality tomato yield in our latitudes is inconceivable without additional lighting. Changes in biochemical composition are mainly dependent on the light received by the plant. During the winter months, natural daylight at 55 ° latitude is insufficient to provide the necessary vegetation for fruit-bearing vegetables. The aim of this study is to investigate the changes in the biochemical composition of tomato fruits by using less conventional lighting methods, which could offer potential energy savings by providing higher levels of biologically active substances in tomatoes. The study was conducted in a greenhouse of Latvia University of Life Sciences and Technologies during the winter season 2018-2019, using a 16-hour photoperiod. LED, Induction, and High Pressure Sodium Lamps (as control) were used in the study. These lighting devices, with some differences, simulate daylight. Three tomato cultivars: ‘Diamont F1’, Encor F1’and ‘Balzano F1’were studied. The study specified the tomato yield and the following biochemical parameters: soluble sugars (BRIX), vitamin C, organic acids, lycopene, carotenoids, phenols and flavonoids. As expected, the yield and species-specific pigment content of tomato fruit is largely dependent on the genetics of the variety. On the other hand, biologically active compounds such as organic acids, soluble sugars, ascorbic acid and flavonoids undergo more changes due to the composition of the light. The obtained biochemical parameters give an opportunity to consider different illumination methods and the need to carry out further studies in order to confirm the conclusions. Significantly higher yields were observed in the variant with conventionally used high pressure sodium lamps. In mean time, it should be noted that in the variant with LED lamps, higher content of lycopene as well as phenols and vitamin C were observed.

Subalpine Fir (Abies laciocarpa) and Norway Spruce (Picea abies) Seedlings Show Different Growth Responses to Blue Light

Blue light (BL) affects different growth parameters, but information about the physiological effects of BL on conifer seedlings is limited. In northern areas, conifer seedlings are commonly produced in heated nursery greenhouses. Compared with Norway spruce, subalpine fir seedlings commonly show poor growth in nurseries due to early growth cessation. This study aimed to examine the effect of the BL proportion on the growth and development of such conifer seedlings in growth chambers, using similar photosynthetic active radiation, with 5% or 30% BL (400–500 nm) from high pressure sodium (HPS) lamps (300 μmol m−2 s−1) or a combination of HPS (225 μmol m−2 s−1) and BL-emitting diodes (75 μmol m−2 s−1), respectively. Additional BL increased transpiration and improved the growth of the Norway spruce seedlings, which developed thicker stems, more branches, and a higher dry matter (DM) of roots and needles, with an increased DM percentage in the roots compared with the shoots. In contrast, under additional BL, subalpine fir showed reduced transpiration and an increased terminal bud formation and lower DM in the stems and needles but no change in the DM distribution. Since these conifers respond differently to BL, the proportion of BL during the day should be considered when designing light spectra for tree seedling production.

Modelling and Simulation of Integrated Topology of DC/DC converter for LED Driver Circuit

With the increase in technological advancements and impetus to work for the reduction of electrical energy consumption among different types of consumers, there is a primary need to take into account all forms of energy efficiency improvement methods available for electric and electronic equipment been used. It has been noticed that in commercial lighting, in terms of efficiency light-lamps based on light-emitting diodes(LEDs) are far better as compared to those where traditional high pressure sodium (HPS) lamps which are still in use in major underdeveloped and developing areas worldwide in specifically street lighting. The LED have numerous advantages such as high luminous efficiency, life span and it has no mercury in its composition. Therefore, recently researchers of this area has been setting a goal to utilize LED as a good alternative to save electricity from major parts of this planet. In this paper simulation of LED driver circuit is presented to utilize the 12 V LED lighting strip which has been used in Indian hawkers/small shopkeepers since a long time.

Quantification of Spectral Perception of Plants with Light Absorption of Photoreceptors.

Although plant responses to artificial lighting spectra often produce abnormal morphogenesis and reduced productivity, no quantification method to determine how plants perceive and respond to light has been available. Our objective in this study was to test whether a plant’s spectral perception can be quantified using the light absorption of its major photoreceptors, phytochrome, cryptochrome, and phototropin. We developed an artificial solar lamp and three different light sources, based on a high-pressure sodium lamp, a fluorescent lamp, and red and blue light-emitting diodes, whose absorption by photoreceptors was equal to that of the standard solar spectrum. Cucumber plants grown under the artificial solar and developed light sources showed normal photomorphogenesis and were indistinguishable from each other. Plants grown under unmodified commercial light sources had abnormal photomorphogenesis that made them short and small. The photosynthetic rate was higher under the unmodified light sources; however, dry masses were highest under the artificial solar and modified light sources, indicating that the cucumber plants are optimized to the solar spectrum. Our results clearly demonstrate that the spectral perceptions of plants can be quantified using the light absorption of their photoreceptors, not visual color or spectra. We expect that our findings will contribute to a better understanding of plant perceptions of and responses to light quality, and improve the productivity of plants cultivated under artificial light.

Susceptibility of LED street lamps to voltage dips

There is an ongoing transition from high-pressure sodium lamps to LED street lamps that offer higher efficiency, cost saving and better photometric performance. This transition could lead to unintended consequences such as light flicker and extinguishing in street lighting applications when they are exposed to voltage dips. The goal of this paper is to analyse the light intensity variation of various street lamps when they are exposed to voltage dips. Several performance metrics for quantifying immunity of lamps have been proposed. Values for these metrics are obtained by applying artificial voltage dips to lamps. For voltage dips with residual voltage above 38%, lamps are immune in terms of a short-term light flicker metric. For residual voltage above 25%, light intensity reduces but without extinguishing. Compared to an incandescent lamp and high-pressure sodium lamp, LED street lamps exhibit longer zero-light intensity duration. Most of the studied LED street lamps exhibit uncoordinated light intensity drops, i.e. longer or shifted, with respect to the applied voltage dip. Individual characteristics of LED street lamps require testing before installation to prevent unexpected consequences. Recommendations are given for standardisation committees to implement an assessment method for lighting equipment.

GreenLight – An open source model for greenhouses with supplemental lighting: Evaluation of heat requirements under LED and HPS lamps

Greenhouse models are important tools for the analysis and design of greenhouse systems and for offering decision support to growers. While many models are available, relatively few include the influence of supplementary lighting on the greenhouse climate and crop. This study presents GreenLight, a model for greenhouses with supplemental lighting. GreenLight extends state of the art models by describing the qualitative difference between the common lighting system of high-pressure sodium (HPS) lamps, and the newest technology for horticultural lighting - the light-emitting diodes (LEDs). LEDs differ from HPS lamps in that they operate at lower temperatures, emit mostly convective heat and relatively little radiative heat, and can be more efficient in converting electricity to photosynthetically active radiation (PAR). These differences can have major implications on the greenhouse climate and operation, and on the amount of heat that must be supplied from the greenhouse heating system. Model predictions have been evaluated against data collected in greenhouse compartments equipped with HPS and LED lamps. The model predicted the greenhouse's heating needs with an error of 8–51 W m −2 , representing 1–12% of the measured values; the RMSE for indoor temperature was 1.74–2.04 °C; and the RMSE for relative humidity was 5.52–8.5%. The model is freely available as open source MATLAB software at https://github.com/davkat1/GreenLight . It is hoped that it may be further evaluated and used by researchers worldwide to analyse the influence of the most recent lighting technologies on greenhouse climate control. • Model for lighting in greenhouses, including HPS and LED lamps, was developed. • Model was evaluated using data from a greenhouse with HPS and LED top-lights. • Model evaluates energy requirements of the greenhouse with an accuracy of 1–12%. • Model predicts indoor temperature and humidity with an RRMSE of 6–11%. • Model is publicly available in free open source format.

Dependence of Current Harmonics of Greenhouse Irradiators on Supply Voltage

The article describes the results of the study concerning the effect of the voltage level on current harmonic composition in greenhouses irradiators. It is found that its change affects the level of current harmonics of all types of the studied greenhouse irradiators. With decrease of nominal supply voltage by 10 %, the total harmonic distortion THDi decreases by 9 % for emitters equipped with high pressure sodium lamps (HPSL), by 10 % for emitters with electrode-less lamps and by 3 % for LED based emitters. With increase of nominal supply voltage by 10 %, THDi increases by 23 % for lighting devices equipped with HPSL, by 10 % for irradiators with electrode-less lamps and by 3 % for LED based emitters. Therefore, changes of supply voltage cause the least effect on the level of current harmonics of LED based emitters and then the emitters with electrode-less lamps. Change of the level of supply voltage causes the greatest effect on the level of current harmonics of HPSL based irradiators. Mathematical models of dependence of THDi on the level of supply voltage for greenhouse emitters equipped with LED, electrode-less lamps and HPSL lamps were formulated. These mathematical models may be used for calculations of total current when selecting transformers and supply cable lines for greenhouse lighting devices, for design of new or reconstruction of existing irradiation systems of greenhouse facilities, and for calculation of power losses in power supply networks of greenhouse facilities during feasibility studies for energy saving and energy efficiency increasing projects.

Obtaining high quality potato seed material on aerohydroponic installations

The results of the study on the production of potato minitubers by aeroponic and aero-hydroponic methods, which are non-substrate methods of growing plants, are presented. In order to develop technologies for growing virus-free potato seed material in closed systems, experiments on growing potato minitubers in multiuse aeroponic systems were conducted. Early-ripening potato varieties Rosara, Antonina and Yubilyar, mid-ripening Solnechny variety, and S-112 and Ch hybrids were used as the tested potato varieties. The plant growing cycle was divided into three phases: adaptation, growth, and tuberization. For each phase, different cultivation parameters were used. As a light source, highpressure sodium lamps DNaT 400 were used. The quantitative yield of potato minitubers per one plant on this type of systems was as follows: Antonina variety – 15.3 pcs., Yubilyar variety – 23 pcs., Hybrid Ch – 28.1 pcs., Hybrid S-112 – 30.2 pcs., Solnechny variety – 30.3 pcs., Rosara variety – 43.9 pcs. The effect of various light sources on the quantitative yield of potato minitubers of Nevsky and Yubilyar varieties was studied for this type of systems. Cultivation of potatoes in these systems was carried out according to the technology described, but using two different types of light sources. In the control variant, high-pressure sodium lamps DNaT 400 were used, in the experimental variant, LED lamps produced by CoB (full spectrum) technology with a passive cooling system were used. The use of LED lighting on Nevsky variety led to a statistically signifi cant increase in the quantitative yield of potato minitubers from one plant compared to the control, by 20.88%. The prospects of using Fagro aero-hydroponic systems for adaptation of potato microplants and for obtaining potato minitubers of Rosara and Solnechny varieties were shown. The quantitative yield of potato minitubers per plant on this type of installations was 46.9 pcs. for Rosara variety, and 56.7 pcs. for Solnechny.

Supplemental Light-Emitting Diode Inter-Lighting Increases Tomato Fruit Growth Through Enhanced Photosynthetic Light Use Efficiency and Modulated Root Activity.

We investigated the effect of supplemental LED inter-lighting (80% red, 20% blue; 70 W m−2; light period 04:00–22:00) on the productivity and physiological traits of tomato plants (Flavance F1) grown in an industrial greenhouse with high pressure sodium (HPS) lamps (235 W m−2, 420 µmol m−2 s−1 at canopy). Physiological trait measurements included diurnal photosynthesis and fruit relative growth rates, fruit weight at specific positions in the truss, root pressure, xylem sap hormone and ion compositions, and fruit quality. In the control treatment with HPS lamps alone, the ratio of far-red to red light (FR:R) was 1.2 at the top of the canopy and increased to 5.4 at the bottom. The supplemental LED inter-lighting decreased the FR:R ratio at the middle and low positions in the canopy and was associated with greener leaves and higher photosynthetic light use efficiency (PLUE) in the leaves in the lower canopy. The use of LED inter-lighting increased the biomass and yield by increasing the fruit weight and enhancing plant growth. The PLUE of plants receiving supplemental LED light decreased at the end of the light period, indicating that photosynthesis of the supplemented plants at the end of the day might be limited by sink capacity. The supplemental LED lighting increased the size of fruits in the middle and distal positions of the truss, resulting in a more even size for each fruit in the truss. Diurnal analysis of fruit growth showed that fruits grew more quickly during the night on the plants receiving LED light than on unsupplemented control plants. This faster fruit growth during the night was related to an increased root pressure. The LED treatment also increased the xylem levels of the phytohormone jasmonate. Supplemental LED inter-lighting increased tomato fruit weight without affecting the total soluble solid contents in fruits by increasing the total assimilates available for fruit growth and by enhancing root activity through an increase in root pressure and water supply to support fruit growth during the night.

Effects of Supplemental Light Source on Basil, Dill, and Parsley Growth, Morphology, Aroma, and Flavor

Broad-spectrum high-pressure sodium (HPS) lamps are the standard for greenhouse supplemental lighting. However, narrow-spectra light-emitting diodes (LEDs) offer potential benefits for enhancing growth, photosynthesis (Pn), and secondary metabolites in culinary herbs. Our objective was to quantify the effect of supplemental light source and spectra on growth, gas exchange, aroma, and flavor of culinary herbs. Basil (Ocimum basilicum ‘Nufar’), dill (Anethum graveolens ‘Fernleaf’), and parsley (Petroselinum crispum ‘Giant of Italy’) were transplanted into hydroponic systems in a glass-glazed greenhouse. Plants were provided with a supplemental photosynthetic photon flux (PPF) density of 100 μmol·m−2·s–1 from an HPS lamp or LEDs with a low blue (B) to red (R) light ratio of 7:93 [low blue (LB)] or high B:R at 30:70 [high blue (HB)]. Compared with plants grown under HPS lamps, basil grown under LB and HB LED lighting was shorter, while only HB-grown parsley was shorter; height of dill was unaffected by light source. Basil and parsley shoot fresh weight was lower for HB-treated plants compared with HPS, though dill was unaffected by supplemental light source. Shoot dry mass of basil, dill, and parsley was unaffected by light source. Both LED treatments increased Pn for basil and parsley compared with HPS-grown plants. Stomatal conductance (gS) was higher under LB and HB for basil compared with HPS in the morning and evening, but only HB-treated parsley was higher than HPS lighting in morning. Basil grown under LB, and parsley under both LEDs had lower chlorophyll fluorescence than those under HPS by the evening, but all three species had more chlorophyll b under LB light than HPS. Essential oil and phenolic accumulation were influenced by supplemental light treatment and responses varied among species. Lighting from LEDs resulted in a 2-fold increase in orientin and myristicin for basil and dill, respectively, while HB increased dillapiole concentration by 89% compared with HPS-grown dill. Notably, quercetin concentration was 2.8 times higher in dill grown under HB compared with HPS. Myrcene increased in all three species under either one (basil HB; dill LB) or both (parsley) LED lights compared with HPS. The increased content of aromatic and flavor compounds demonstrates the potential of supplemental lighting systems using specific wavelengths to add value; but the use of supplemental lighting requires an understanding of the additional stress on the photosynthetic mechanisms and the subsequent effect on biomass accumulation.

Automated Extraction of Street Lights From JL1-3B Nighttime Light Data and Assessment of Their Solar Energy Potential

To realize energy conservation and environmental protection, solar street lights have been widely used in urban areas in China. To reasonably and effectively utilize solar street lights, the original street lights must be located, and the solar street light potential must be assessed. The Jilin1-03B (JL1-3B) satellite provides next-generation nighttime light data with a high spatial resolution and in three spectral bands. Consequently, the street lights can be extracted from the nighttime light data. We used the road network dataset from the open street map with a specific buffer to extract the road area as a constraint region. Next, the grayscale brightness of JL1-3B images was obtained by integrating all the three bands to locate the street light by using a local maximum algorithm. Then, the values of the original three bands were utilized to classify the types of street lights as high-pressure sodium (HPS) lamps or light-emitting diode lamps. Finally, we simulated the replacement of all the HPS lamps with solar street lights and assessed the corresponding solar energy potential by using the digital surface model data and hourly cloud cover data through the SHORTWAVE-C model. The accuracy of location of the street lights was approximately 90%. Replacing an HPS lamp by one solar street light for 20 years can save 1.85 × 104 kWh of electrical energy, 7.41 t of standard coal, 5.03 t of C emissions, 18.47 t of CO2 emissions, 0.55 t of SO2 emissions, and 0.28 t of NOX emissions.

The effect of greenhouse irradiators on the load factor of step-down transformers

The aim of the work is to determine the permissible load factors of step-down transformers when powering various types of greenhouse irradiators. All examined irradiators have nonlinear volt-ampere characteristic and generate upper current harmonics. The object of research are greenhouse illuminators with high pressure sodium lamps, induction and light-emitting diodes greenhouse illuminators (LED) with active and passive power factor. The permissible load factors of transformers are calculated using obtained data: for high-pressure sodium lamp light is 0.95 max; for LED lamps with active power factor corrector – 0.76 max; for LED lamps with passive power factor correction – 0.59 max; for electrodeless lamp light – 0.98 max. To reduce current harmonics in systems with LED lamps and to increase the load factor of transformers, it is necessary to apply special devices – active or passive harmonic filters. For greenhouse irradiators with sodium lamps and induction irradiators, the use of harmonic filters is not required.

The Influence of the Spectral Properties of the Lighting Environment on Light Absorption by Lettuce Leaves and the Net Productivity of Lettuce

Abstract—The efficiency of light absorption with different spectral compositions by lettuce leaves and the choice of optimal conditions of the lighting environment for increasing the productivity and quality of plant products grown under artificial lighting conditions were investigated. Lettuce of the Typhoon variety was grown by a thin-layer panoponic method in an automated growth chamber with five variants of different light sources. A non-damaging method developed by the authors for the measurements of the absorption spectra of leaves in vivo made it possible to determine the influence of the spectral composition of the radiation on the optical characteristics that reflect the physiological state of the plants. The amount of absorbed photon energy increased by ~140 μmol m–2 s–1 with an increment in lettuce leaf biomass by 1 g for 10 days under maximum productivity conditions; the values of the light absorption index below 70 μmol m–2 s–1 corresponded to the samples with minimum results in growth characteristics. The similarity of the spectral characteristics of lighting in the region of photosynthetically active radiation of HPS lamps (High-Pressure Sodium lamps) and LED lamps, which emit yellow light, and almost the same proportion of photosynthetically active photons in the blue, green, and red regions of the spectrum led to the same increment of light absorption in the process of plant development. However, a significant difference in the productivity of lettuce (~50%), as well as the growth, development, and biochemical composition indicated a better effect of the HPS lamps on the properties of the plant culture. The obtained data indicated that the illumination with an intensity of ~25 μmol m–2 s–1 in the range of 400–500 nm, ~150 μmol m–2 s–1 in the range of 500–600 nm, and ~150 μmol m–2 s–1 in the range of 600–700 nm led to high productivity of the lettuce.

Neural network identification of a nonlinear model of a high-pressure sodium lamp

The article is devoted to the identification of a high-pressure sodium lamp nonlinear model parameters based on neural network technologies. Identification was carried out using a dynamic neural network. The model had 17 parameters based on second order differential equations. As a result, out of 17 parameters, four were selected that accurately reflect the real picture of the model.