Urgent need to reduce emissions of carbon and other harmful substances in order to combat climate change is becoming more acute every year. Research presented in this work has the main goal of drawing additional attention to the technology of delivering daylight to rooms with constant presence of people, animals, and plants, which allows us to relieve some of the problems of energy and environment, for example, by reducing volume of electric lighting.
This paper presents a detailed study of efficiency of light beam passing through a mirrored hollow tubular light guide, on basis of which the derived mathematical dependencies, calculation tables, necessary for practical work when modelling energy-efficient lighting systems, based on mirrored hollow tubular light guides, are presented. In addition, energy levels of the light flux were studied, as a result the energy efficiency resources of lighting systems were identified and directions for possible practical application of these resources formulated.

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4. Pleshkov, S. Yu., Brakale G., Kuznetsov A.L. Design Project of Combined Lighting of a Coworking Area of the Youth Centre in the City of Milan Using Mirrored Hollow Tubular Light Guides // Light & Engineering, 2022, Vol. 30, # 4, pp. 4–13.
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8. Soloviev, A.K. Scientific Basis for Increasing Energy Efficiency of Overhead Natural Lighting Systems in Industrial Buildings Using Light Field Theory [Nauchnyye osnovy povysheniya energoeffektivnosti verkhnikh sistem yestestvennogo osveshcheniya promyshlennykh zdaniy s ispol’zovaniyem teorii svetovogo polya] / Dissertation for the Doctor degree of Technical Sciences, MGSU, 2011, Moscow.
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OLED technology is widely used in various displays, which operate in a wide range of temperatures. For such devices, it is necessary to maintain the luminance and chromaticity coordinates at the given level when the external temperature changes. In this work, a program was developed that, based on the electro-physical characteristics and electroluminescence spectra of a white OLED sample at different temperatures and currents, as well as the spectral characteristics of the coloured filters, allows for selection of currents in the range of (1–25) mA, applied to each subpixel in such a way as to converge the chromaticity coordinates to the specified values. Various chromaticity coordinates were tested in the process of program execution, including CIE sources of type A, type B, type C, and type D65. In each of these cases, the program significantly reduced the difference in chromaticity coordinate changes with temperature. The obtained results will be used for gamma correction of micro-displays produced at the Cyclone Research Institute during their operation at a wide range of temperatures.

A method is proposed for calculating the asymmetric luminous intensity distribution of a luminaire for stationary road lighting, in which the properties of directional reflection of light from the road surface are used to the greatest extent. The method is based on the analytical relationship of the luminaire’s luminous intensity in the direction of the calculated point with the luminance of the road surface at this point in the direction of the driver, expressed in terms of the reduced luminance coefficient of this coating. The main provisions and algorithm of the method are given. The features of the calculation depending on the angle of inclination of the luminaire and the layout of the luminaires relative to the direction of movement are shown. According to a specially developed computer program, an example of calculating the asymmetric light distribution of a luminaire is executed and its effectiveness is evaluated in comparison with traditional symmetrical luminous intensity distribution.

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The development of computer technology and mathematical methods for solving the global illumination equation gave rise to computer-aided lighting design systems, which in turn led to a genuine revolution in the practice of lighting design. Deep use of information technologies is possible only with a developed mathematical description of the light field in a lighting installation. It is the theory of the light field, based on the theory of radiation transfer, that allows us to present all lighting technology from a single conceptual point of view. The mathematical apparatus of the theory of the light field is the basis of the algorithms of all modern programs for the calculation of lighting installations, lighting devices, radiation, reflection, and transmission of light by real objects. As a result, there was a need for a significant change in light and engineering education. At the subdepartment of Light and Engineering of the NRU “MEI”, following modern trends, new and new courses have appeared and are appearing, allowing students to obtain relevant knowledge. One of the new courses planned at the subdepartment is a course of mathematical modelling in light and engineering. It involves an in-depth study of the internal structure of computer-aided design systems, which will allow obtaining specialists capable of solving non-standard tasks, creating funds for solving these tasks and conducting research.

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This article focuses on the issue of street lighting in Tashkent, Uzbekistan, discussing its development stages and current assessment. The project aimed to give the city a modern appearance while preserving its rich history. It involved the implementation of modern energy-efficient equipment and lighting technologies that meet the requirements for lighting main streets, district streets, neighbourhoods, and residential areas. The project successfully achieved an average energy savings of 60 % and improved lighting quality by utilizing LED technology. The lighting now offers a comfortable experience resembling natural white light (4000–4500) K with a colour rendering index of at least 80. Additionally, an automatic remote-control system for outdoor lighting was developed and implemented, along with appropriate control cabinets. The transition to LED lighting and automatic control systems, alloweda flexible and differentiated approach to lighting the city while maintaining high-quality lighting. In the future, this technology can be further upgraded to introduce even more energy-efficient LED chips with minimal financial and material costs.

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4. TEDAŞ – MLZ/2010–057.D, Turkish Electricity Distribution Corporation, Strategy Development Department, LED Based Road Lighting Luminaires Technical Specifications, Revised in 2020, in Turkish.
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This simulation-based study investigates the potential of tubular daylight guidance systems (TDGS) to enhance daylight availability in historical buildings. Historical buildings often face challenges in providing sufficient daylight to non-lit areas without altering the building’s facade. TDGS offer a passive, building-integrated solution that redirects daylight to target areas while preserving the building’s originality. The study focuses on a historic passage building without ground floor openings and aims to improve visual comfort and daylight availability. Climate Studio software is used to assess the current daylighting conditions and to simulate various scenarios for TDGS implementation. The study considers four TDGS alternatives with different diameters, evaluating their impact on useful daylight illuminance (UDI) and spatial daylight autonomy (sDA). The findings reveal significant increases in UDI and sDA, ranging from 68.7 % to 403.7 %, and from 79.9 % to 1813.6 %, respectively, depending on the tube diameter. These results underscore the importance of daylight tube diameter in increasing the availability and distribution of useful daylight. The study emphasizes the potential of TDGS to optimize daylighting experiences in historical buildings with limited daylight.

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Our daily behaviours and physiological functions are regulated by the brain’s central biological clock. Consistent exposure to bright days and dim nights is crucial for aligning these rhythms. Since we spend much time indoors, electrical lighting is often relied upon to sync our circadian rhythms. A challenge in promoting circadian entrainment through electrical lighting is the lack of a standardized test for assessing how effectively lighting luminaires provide circadian-effective light to occupants. This study introduces a case study, optimum suspended height (OSH), measuring luminaire efficiency in achieving a circadian stimulus criterion (CS: 0.3) and equivalent melanopic illuminance in lx (EML: 240) for 38 office workers, based on performance and comfort criteria. The paper outlines OSH application to individual linear luminaire type, including suspended-mounted fixtures. In this field study, tests were conducted to explore how indoor lighting affects occupants’ cognitive performance and visual perception. Linear suspended LED luminaires (LSL) were installed in an open-plan office at Istanbul Technical University (ITU), where office workers were exposed to different heights of lighting conditions. They took visual attention tests and assessed proofreading comfort, with alertness measured using the Karolinska Sleepiness Scale (KSS) test. The study aimed to understand the impact of visual fatigue on cognitive performance and perception with. These initial findings shed light on the relationship between office lighting changes and occupants’ cognitive performance and visual perception.

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Calculation of output photometric characteristics describing the energy of radiation is an integral part of a lighting device optical system designing. The most common way to solve this problem today is the Monte-Carlo method. However, its significant disadvantage is the low rate of convergence, which often does not allow obtaining the result in an acceptable time even on modern computing systems. Therefore, the search for ways to improve this method does not lose its relevance and is the subject of research by numerous authors. One of these ways is the use of the histogram method known from the theory of statistical modelling, which is reduced to the expansion of the sought-for value in a series of orthogonal functions forming an orthonormal basis. This approach paves the way to eliminate the averaging of the sought-for value and organize the calculation in such a way that any beam passing through the optical system contributes to the distribution function of the entire sought-for response of a receiver. Thus, we achieve an increase in the rate of convergence of the method. Of greatest interest here is the expansion of the sought-for quantity distribution in a series in terms of Legendre polynomials and spherical functions related to them. To date, the described modification of the Monte-Carlo method has been implemented only for the case of lighting devices optical systems with axisymmetric light distribution. In this article, we propose a method that allows to apply the method modification to lighting devices optical systems with arbitrary light distribution. Resulting computational time reduction while solving direct problems allows new ways for solving reverse problems, such as designing of optical systems for a given light distribution.

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The yield and efficiency of cultivation of any crop depends on the quality of the planting material. The most promising method of modern horticulture, which makes it possible to significantly increase its environmental sustainability, is to obtain planting material, improved by culture of isolated tissues in vitro. There is blue honeysuckle, raspberries, garden strawberries, steppe cherries, domestic plums, and other crops studied in vitro in the Udmurt Federal Research Centre of the Ural Branch of the Russian Academy of Sciences (Udmurt FRC UB RAS). The light regime has a great influence on plant growth under in vitro conditions. A review of specialized literature showed the energy efficiency of the pulsed mode of plants irradiation as significantly reducing power consumption compared to stationary (continuous) one with the same quality of the grown products. In the Udmurt FRC UB RAS, pulsed irradiation of garden strawberry explants in vitro made it possible to increase their rooting by 10 %. The mode of irradiation in modern illuminators with LEDs under in vitro conditions can be changed by means of digital automated control systems. This makes it possible to implement an energy-saving pulsed irradiation mode that allows efficient electricity use. The purpose of this work was to develop a digital system for automated control of the operation of the irradiator with LEDs for the implementation of an energy-efficient pulsed mode of plant irradiation in vitro and its experimental testing. Experiments conducted with it on plum micro-cuttings showed that the largest leaf area (119 %) compared to the control was obtained using light pulses with a duration of 0.8 s, which confirms the feasibility of using a pulsed irradiation mode and optimizes its parameters for these conditions.

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The availability of daylight for residential and public spaces is extremely important. However, not always enough light to solve visual problems ensures the quality of the light environment in the room. The development of recommendations for improving the quality of daylighting is an important and urgent task, since the quality of human life and work depends on it, as well as energy savings. A criterion of light saturation of a room has been introduced into the norms, the evaluation characteristic of which is cylindrical illuminance only for electrical lighting. The article presents the results of a fullscale psychophysical experiment to assess the qualitative indicator of natural illumination of rooms with side light openings. The analysis of subjective assessments of observers showed the absence of a relationship between high estimates of the saturation of the room with light and the values of the relative horizontal illuminance of the daylight factor Dh, as well as the relative cylindrical illuminance of the Dc. However, there is a correlation between the feeling of comfort of the light environment and the values of the Dc/Dh ratio. The proposals on the normalized value and its values corresponding to the levels of saturation with daylight of the room are formulated. The analysis of the data obtained from the results of the experiment allowed us to establish that the quality of lighting of the workplace and the room as a whole is highly appreciated by the observer in terms of saturation level if the ratio of Dc/Dh in the centre of the room is located in the interval 1–1.3, while the value of the cylindrical illuminance Ec at the point furthest from the light transmission with a high assessment of light saturation by observers is Ec = 120 lx, Dc = 2 %.

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In response to the control problem and power consumption problem of outdoor illumination in imperfect lighting environments, a deep learning based automatic control method for street luminaires in imperfect lighting environments is studied and an automatic control model for street lights in an imperfect lighting environment based on deep learning is constructed. Use sensors to collect temperature, humidity, air pressure, and haze values that are significantly correlated with the brightness of ilumination in the same environment. Based on the collected data, use a deep learning short-term memory network to predict the current street illumination brightness, and use the Whale Optimization Algorithm to optimize network parameters. Using window filtering and one-dimensional Kalman filtering to filter the predicted data of illumination, the predicted street illuminance data after filtering is compared with the expected values. Based on this, a discretized PID controller (proportional–integral–derivative controller) is used to output the dimming value to achieve street lamp control. The experimental results show that this method can accurately predict the current characteristic of street lamps, and has good brightness control results in poor lighting environments, as well as better energy-saving performance.

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The conditions of Ottoman architecture persisted during the republican period at the turn of the 20th century. Later, radical changes in the structure of the state affected the field of architecture, and changes in the world were reflected in our country. The structures that are the subject of architectural debates are typically early republican period buildings, which were built between 1920s and 1950s. On the other hand, in past buildings, the interior design criteria that are important for the user in interior design have been the subject of interest in various disciplines. Lighting – daylighting and electric lighting – in different interiors is one of the design criteria that has intrigued many researchers. Laboratories, classrooms, studios, circulation areas, administrative spaces, offices, conference rooms, and wet spaces are all common features of educational buildings. Each of these spaces has unique lighting requirements. The aim of this study is to assess the daylighting performance in the interior and encourage similar studies in historical educational buildings rather than the architectural design of these buildings. Daylighting performance was assessed in the analytical chemistry laboratory at the Ankara University Faculty of Science, block A, which was built during the Second National Architectural Movement and bears the traces of Sedad Hakki Eldem, Emin Onat, and Paul Bonatz. A morning interval (10:00–11:00) where the courses are considered the most productive was chosen for the evaluation. The results were compared and interpreted with the values specified in the standards; the measurement is limited to the day and time interval.

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Increasing age and physiological deterioration make it a safety problem for the elderly to go to the bathroom at night. In order to ensure the safety for the elderly, it is necessary to provide a certain degree of vertical illumination of the eyes and adequate illumination of the ground. However, excessive illumination also affects the rhythm and sleep continuity. This study aims to ensure the safety and rhythmic health of the elderly during the night, and a total of 80 senior citizens were studied. In this study, the type of bedroom light fixtures and night time use were counted, and the sleep quality of older adults was analysed in combination with the Pittsburgh Sleep Quality Index (PSQI) and measured illuminance data. Lighting graphs help to express the problems. The results showed that the mean vertical illuminance of the eyes with the lights on was 75.24 lx (SD=±46.81), and the illuminance of the ground was 25.72 lx (SD=±14.54). 66.25 % of the older adults use the table lamps in the bedroom. The problems with all kinds of the lamps were analysed in light diagrams. The result of the PSQI questionnaire showed a mean score of 8.10 ± 2.463, which scores too high and means bad sleeping condition. There is a high level of ocular illuminance, which affects the rhythm of the elderly people, and the ground illuminance is insufficient, which makes it difficult for the elderly people to notice unsafe factors such as the debris on the ground.

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Alexei A. Korobko
Method for Calculating the Asymmetric Luminous Intensity Distribution for the Road Lighting Luminaire

Sermin Onaygil, Onder Guler, and M. Berker Yurtseven
Evaluation of LED Luminaire Utilizatıon in Road Lighting Installations in Terms of Electrical Energy Qualty

Vladimir P. Budak and Victor S. Zheltov
Mathematical Modelling in Light and Engineering Education

Nina A. Molchina and Tatiana N. Magera
Daylight Quality Assessment of Rooms with Lateral Daylighting by the Room Light Saturation Criterion

Sergey Yu. Pleshkov, Gennaro Bracale, and Alexander L. Kuznetsov
Study of Transmission Efficiency and Energy of a Light Beam in a Mirrored Hollow Tubular Light Guide

Sobitjon S. Tolipov, Madridbek M. Mamazhanov, and Farida S. Agisheva
Lights of the City of Tashkent: the History of One Project

Alexei A. Korobko
Method for Calculating the Asymmetric Luminous Intensity Distribution for the Road Lighting Luminaire

Sermin Onaygil, Onder Guler, and M. Berker Yurtseven
Evaluation of LED Luminaire Utilizatıon in Road Lighting Installations in Terms of Electrical Energy Qualty

Vladimir P. Budak and Victor S. Zheltov
Mathematical Modelling in Light and Engineering Education

Nina A. Molchina and Tatiana N. Magera
Daylight Quality Assessment of Rooms with Lateral Daylighting by the Room Light Saturation Criterion

Sergey Yu. Pleshkov, Gennaro Bracale, and Alexander L. Kuznetsov
Study of Transmission Efficiency and Energy of a Light Beam in a Mirrored Hollow Tubular Light Guide

Sobitjon S. Tolipov, Madridbek M. Mamazhanov, and Farida S. Agisheva
Lights of the City of Tashkent: the History of One Project