Search Results (12)

Countries worldwide have implemented regulations on the green coverage ratio of new buildings to address the urban heat island effect. For example, Taipei City mandates that the green coverage rate of new buildings must be between 40% and 70%, while Singapore requires a green coverage rate of 100% or higher. Consequently, building greening is now a regulatory requirement rather than a preference. This study focuses on developing an indoor light-emitting-diode (LED) hydroponic inverted planting system to utilize ceiling space for expanding green areas in buildings. The light source of this system is suitable for both plant growth and daily lighting, thereby reducing electricity costs. The watertight planting unit does not require replenishment of the nutrient solution during a planting cycle for small plants, which can reduce water consumption and prevent indoor humidity. The modular structure allows various combinations, enabling interior designers to create interior ceiling scapes. Additionally, it is possible to grow aromatic plants and edible vegetables, facilitating the creation of indoor farms. Consequently, this system is suitable for high-rise residential buildings, office buildings, underground shopping malls, and indoor areas with limited or no natural light. It is also applicable to hospitals, clinics, wards, and care centers, where indoor plants alleviate psychological stress and enhance mental and physical health. Full article

The global development of LED lighting in all applications for both public and indoor lighting establishes a very important lever for reducing the carbon impact by significantly reducing energy consumption. Smart lighting will therefore constitute an essential lever in the smart city of tomorrow. The latter is more sustainable and less energy-intensive than other light sources, contributing towards the Sustainable Development Goals set forth by the United Nations (SDGs 7 and 11). With its ease of integration, ergonomics, lightness, and high quality of light, this innovative light source has two major qualities: its energy efficiency and its long service life. However, poor thermal management has catastrophic effects on these two essential criteria. This necessarily requires optimizing thermal management and heat sinks. In some cases, thermal models and simulations can lead to considerable calculation times because they implement many parameters. This work therefore aims to reduce the number of these simulations by applying the method of experimental designs (Taguchi) and analysis of variance (ANOVA) to simulations intended to optimize the dissipation of LED luminaires. We applied the method to a simple finned heat sink model for a unit input power and then to a concrete case of a high-power LED. The control parameters and their respective contributions in the proposed model were studied. The ANOVA results corroborated the conclusions of the Taguchi method, demonstrating a strong agreement between these analytical methods, in which the temperature was adjusted by identifying optimal combinations of parameters. The fields of application relevant to this study include both indoor lighting (false ceiling) and confined spaces with severe sealing constraints such as car headlights or the optical blocks of urban luminaires. Full article

This study presents a significant advancement in LED interior lighting through the development and application of Asymmetric Lens–Total Internal Reflection (AL–TIR) optics, with a focus on enhancing lighting uniformity and indoor comfort by simulating sky-like lighting distribution. AL–TIR technology employs asymmetric lenses combined with total internal reflection to efficiently redirect and spread light, achieving a controlled and even ceiling illumination suitable for various interior applications. This research explored the establishment of ideal luminous intensity curves, devised practical AL–TIR optical designs through numerical calculations, and conducted extensive simulations to assess performance in typical indoor environments. Our findings demonstrated substantial improvements in lighting uniformity, with the AL and AL–TIR systems achieving direct illuminance uniformities of 0.78 and 0.83, respectively, compared to traditional tube LEDs at 0.25. These results, validated in several office rooms, highlight the efficacy of AL–TIR optics in revolutionizing indoor lighting design by balancing optimal lighting distribution with occupant comfort and well-being. Full article

A light shelf is a type of natural daylight system that brings natural light from the outside into an indoor space through a reflector and a ceiling surface. The introduction of light shelves has led to studies evaluating their efficiency. However, past studies on light shelves did not consider the diversity of ceiling types when evaluating their performance. Therefore, this study derives fundamental data involving external light shelf designs by evaluating light shelf performance based on the ceiling type present using a light environment simulation method. This study analyzed the indoor illuminance distribution with Radiance to evaluate the performance according to light shelves and indoor space types. The results derived from this study are as follows: (1) In the case of a flat ceiling, the performance of an external light shelf can be improved by increasing its angle and width. However, adjusting the external light shelf angle to 30° during the middle of the season and 20° in winter is ineffective because natural light is not reflected by the ceiling surface. (2) The performance of a light shelf can be improved by increasing the slope and curvature of the ceiling types specified in this study. However, setting the light shelf angle to 30° during the middle season and to 30° and 20° in winter, when external natural light entering the indoor space is not reflected by the ceiling surface, is ineffective due to the low levels of daylight performance, regardless of the type of space. (3) To increase uniformity levels in gable ceilings and curved ceilings, it is advantageous to increase the number of reflections and diffusion areas on the ceiling’s surface due to the uniqueness of these ceiling shapes. Furthermore, the optimal external light shelf angle for these ceiling types differs from that of other types. (4) Regarding the appropriate external light shelf size according to a particular ceiling type, installing an angle-controllable external light shelf with a width of 1.2 m can improve daylight performance. Full article

Indoor smart-farming based on artificial grow lights has gained attention in the past few years. In modern agricultural technology, the growth status is generally monitored and controlled by radio-frequency communication networks. However, it is reported that the radio frequency (RF) could negatively impact the growth rate and the health condition of the vegetables. This work proposes an energy-efficient solution replacing or augmenting the current RF system by utilizing light-emitting diodes (LEDs) as the grow lights and adopting visible light communications and optical camera communication for the smart-farming systems. In particular, in the proposed system, communication data is modulated via a 24% additional green grow LED light that is also known to be beneficial for the growth of the vegetables. Optical cameras capture the modulated green light reflected from the vegetables for the uplink connection. A combination of white ceiling LEDs and photodetectors provides the downlink, enabling an RF-free communication network as a whole. In the proposed architecture, the smart-farming units are modularized, leading to flexible mobility. Following theoretical analysis and simulations, a proof-of-concept demonstration presents the feasibility of the proposed architecture by successfully demonstrating the maximum data rates of 840 b/s (uplink) and 20 Mb/s (downlink). Full article

Topics concerning autonomous navigation, especially those related to positioning systems, have recently attracted increased research attention. The commonly available global positioning system (GPS) is unable to determine the positions of vehicles in GPS-shaded regions. To address this concern, this paper presents a fuzzy-logic system capable of determining the position of a moving robot in a GPS-shaded indoor environment by analyzing the chromaticity and frequency-component ratio of LED lights installed under the ceiling. The proposed system’s performance was analyzed by performing a MATLAB simulation of an indoor environment with obstacles. During the simulation, the mobile robot utilized a fuzzy autonomous navigation system with behavioral rules to approach targets successfully in a variety of indoor environments without colliding with obstacles. The robot utilized the x and y coordinates of the fuzzy positioning system. The results obtained in this study confirm the suitability of the proposed method for use in applications involving autonomous navigation of vehicles in areas with poor GPS-signal reception, such as in tunnels. Full article

In this paper, a patient mobility support scheme for indoor non-directed optical body area networks (OBAN) is presented. The OBAN is an optical healthcare system where medical sensors are installed on various parts of the patient’s body and are connected to an optical coordinator for transmitting the physiological signals via optical wireless links. In the proposed scheme, a white light-emitting diode (LED) was employed as the optical coordinator that was mounted on the patient body, while a photodetector (PD) was used as the receiver installed at the ceiling. We considered three practical mobility scenarios in terms of the location of the coordinator: (i) Shoulder, (ii) wrist, and (iii) both shoulder and wrist. The analytical channel model for multiple reflections in a non-directed OBAN was developed and validated in the form of simulations. In addition, experiments were carried out to verify the effectiveness of the proposed mobility scheme. It was found that the third scenario (shoulder and wrist) performed best, showing a bit error rate (BER) of 1.2 × 10⁻⁶ at a distance of 1.25 m. The experimental results demonstrated that the proposed mobility support scheme in the OBAN added an additional degree of freedom to patients with reliable performances. Full article

In this paper, our first attempt at visible light communication system, based on software defined radio (SDR) and implemented in LabVIEW is introduced. This paper mainly focuses on two most commonly used types of LED lights, ceiling lights and LED car lamps/tail-lights. The primary focus of this study is to determine the basic parameters of real implementation of visible light communication (VLC) system, such as transmit speed, communication errors (bit-error ratio, error vector magnitude, energy per bit to noise power spectral density ratio) and highest reachable distance. This work focuses on testing various multistate quadrature amplitude modulation (M-QAM). We have used Skoda Octavia III tail-light and Phillips indoor ceiling light as transmitters and SI PIN Thorlabs photodetector as receiver. Testing method for each light was different. When testing ceiling light, we have focused on reachable distance for each M-QAM variant. On the other side, Octavia tail-light was tested in variable nature conditions (such as thermal turbulence, rain, fog) simulated in special testing box. This work will present our solution, measured parameters and possible weak spots, which will be adjusted in the future. Full article

The application of autonomous vehicles has grown dramatically in recent years. Not only has the rail-guided vehicle (RGV) been used widely in traditional production lines, the automatic guided vehicle (AGV) has also been increasingly used. Positioning and path planning are two major functions of autonomous vehicles; however, there are many ways to fulfill the above requirements. The infrared remote control has been heavily and successfully used in home appliances for decades, which has encouraged us to apply this mature and cost-effective technology to an autonomous vehicle. By decoding the coded signal from the infrared light-emitting diode (LED), which is equipped on the ceiling, the autonomous vehicle can be positioned with an accuracy of less than 50 mm. On the other hand, by changing the beam pattern of infrared light from the ceiling, an invisible route can be produced on the ground. That is to say, instead of the traditional rail-guided method, these invisible paths can guide the autonomous vehicle. We have implemented a prototype of an autonomous vehicle system based on the above concept, with the aim of creating a simple and reliable approach for the navigation of an indoor autonomous vehicle. Full article

A high luminance contrast between windows and surrounding surfaces can increase the risk of discomfort glare, which can diminish office workers’ satisfaction and productivity. Accordingly, it can lead to occupant interventions, such as drawing window blinds or increasing electric light levels, which are intended to enhance indoor visual comfort but counterproductively act to increase energy consumption. Increasing the luminance of the areas surrounding the windows using a supplementary lighting system, such as wall-washing with light emitting diode (LED) linear luminaires, could reduce discomfort glare arising from windowed walls. This paper reports on the results of a study in a typical office room in Brisbane, Australia. The outcomes of this study indicate that creating a luminance contrast of between 11:1 and 12:1 on the window wall in an office room with a 45% window-to-exterior-wall ratio using a supplementary LED system leads to improved subjective assessments of window appearance. The results suggest that such an enhancement could significantly reduce discomfort glare from windows, as well as diminishing the likelihood of the users intending to turn on the ceiling lights or to move the blinds. Full article

Exploiting the increasingly wide use of light emitting diodes (LEDs) lighting, in this paper we propose a reversed indoor positioning system (IPS) based on LED visible light communication (VLC) in order to improve indoor positioning accuracy. Unlike other VLC positioning systems, we employ two annular receivers with multi-photodiodes installed on the ceiling to locate the persons who carry LEDs. The basic idea is using multi-photodiodes to calculate the angle while using the received signal strength (RSS) method to calculate the distance. The experiment results show that the effective positioning range of the proposed system is 1.8 m when the distance between two receivers is 1.2 m. Moreover, a positioning error less than 0.2 m can be achieved under the condition that the radius of the PIN circle is between 0.16 m and 0.2 m, and the distance of the transmitter-receiver plane is less than 1.8 m, which will be effective in practice. Full article

Recently, it is believed that lighting and communication technologies are being replaced by high power LEDs, which are core parts of the visible light communication (VLC) system. In this paper, by taking advantages of VLC, we propose a novel design for an indoor positioning system using LEDs, an image sensor (IS) and an accelerometer sensor (AS) from mobile devices. The proposed algorithm, which provides a high precision indoor position, consists of four LEDs mounted on the ceiling transmitting their own three-dimensional (3D) world coordinates and an IS at an unknown position receiving and demodulating the signals. Based on the 3D world coordinates and the 2D image coordinate of LEDs, the position of the mobile device is determined. Compared to existing algorithms, the proposed algorithm only requires one IS. In addition, by using an AS, the mobile device is allowed to have arbitrary orientation. Last but not least, a mechanism for reducing the image sensor noise is proposed to further improve the accuracy of the positioning algorithm. A simulation is conducted to verify the performance of the proposed algorithm. Full article