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Automated daylight-linked control systems performance with illuminance sensors for side-lit offices in the Mediterranean area
摘要： Daylight-linked control systems (DLCSs) installation guarantees noticeable benefits, optimizing both energy saving and occupants' visual comfort. These systems performances are influenced by different factors, above all daylight availability. To deepen this issue, daylight illuminance measurements were performed at the work-plane and at the ceiling (corresponding to the position of a typical closed-loop photosensor) in a side-lit office during summer and winter. The office was equipped with two windows: one facing South and the other facing West. For each orientation, starting from measurements, the functioning of different closed-loop DLCSs was modelled. Results underlined that proportional dimming systems guarantee the best performances for each analyzed case, however they demonstrated that, for specific indoor daylight levels and task illuminances, switching systems can be profitable as well. It was underlined that, for specific daylight conditions, integral reset control guarantees performances comparable with those of proportional dimming. However, it was observed that for integral reset and multi-levels stepped systems, the risk that total illuminances (daylight plus electric light) are lower than the prescribed ones is higher than the other analyzed control strategies.
关键词： Daylight illuminance measurements,Mediterranean area daylighting,Automated daylight-linked control systems,Energy savings,Daylight
更新于2025-09-23 15:22:29
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[ACM Press the 24th Annual International Conference - New Delhi, India (2018.10.29-2018.11.02)] Proceedings of the 24th Annual International Conference on Mobile Computing and Networking - MobiCom '18 - Battery-Free Eye Tracker on Glasses
摘要： This paper presents a battery-free wearable eye tracker that tracks both the 2D position and diameter of a pupil based on its light absorption property. With a few near-infrared (NIR) lights and photodiodes around the eye, NIR lights sequentially illuminate the eye from various directions while photodiodes sense spatial patterns of reflected light, which are used to infer pupil’s position and diameter on the fly via a lightweight inference algorithm. The system also exploits characteristics of different eye movement stages and adjusts its sensing and computation accordingly for further energy savings. A prototype is built with off-the-shelf hardware components and integrated into a regular pair of glasses. Experiments with 22 participants show that the system achieves 0.8-mm mean error in tracking pupil position (2.3 mm at the 95th percentile) and 0.3-mm mean error in tracking pupil diameter (0.9 mm at the 95th percentile) at 120-Hz output frame rate, consuming 395μW mean power supplied by two small, thin solar cells on glasses side arms.
关键词： photodiodes,near-infrared,pupil tracking,energy savings,wearable,battery-free,eye tracker
更新于2025-09-23 15:21:21
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Performance Analysis of Single-Stage LED Buck Driver Topologies for Low-Voltage DC Distribution Systems
摘要： The demand for lean protein is the main reason for raising domesticated birds in poultry farms for the purpose of farming meat or eggs for food. In these poultry farms, artificial lighting system is an essential factor for the success of the commercial production of egg layers and broilers. Lighting loads connected to the existing AC system requires DC power. Nearly 25% of the total power consumed in India is by lighting loads. Therefore, low-voltage DC distribution system is the new requirement of electrical network to improve energy conservation. In this paper, an energy efficient single-stage LED driver topology is proposed as a better alternative to fluorescent lights used in poultry farms. The proposed topology is a phase-shifted buck converter with reduced size of passive components. The converter is mathematically modelled and designed for a power of 24 W LED lights. An experimental prototype is developed for the proposed converter and the results are validated in terms of cost, energy savings, and energy efficiency with various other LED driver topologies like conventional buck converter and interleaved buck converter. Further to justify the outcome of the proposed LED driver, a case study is also done for poultry farms.
关键词： energy savings,Phase-Shifted Buck Converter (PSBC),dimming control,digital controller,LED driver
更新于2025-09-19 17:13:59
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Solar Energy, Photovoltaics, and Domestic Hot Water.. || The Economics of Solar Domestic Hot Water Systems
摘要： Let’s determine whether the purchase of a solar hot water system is a cost-effective investment for your home. We previously calculated the amount of energy needed for your daily requirements as well as the amount of energy available at your location (Chapters 3 and 4). The most practical and cost-effective use of solar energy is its application to heating water. This chapter will discuss the cost savings and graphically illustrate examples of payback periods particular to heating water. If you are constructing a new residence, then you can consider using solar for hot water as well as radiant floor-space heating. In new construction, the total cost of a solar hot water system for both space heating and domestic hot water (DHW) applications would be less costly than attempting to retrofit your existing home. Because heating domestic water versus space heating has the most expedient return on investment, we will concentrate only on the DHW applications and discuss the financial advantage of such systems. Why should conventional methods of heating water continue to be used when there is a more economical method by using the sun’s energy? You may not be able to have 100% of your hot water needs met by solar every day, but it can be a substantial supplement to your daily requirements. The technology of solar water heating is actually an old one; the present-day use of the technology continues to be new.
关键词： solar hot water system,payback periods,domestic hot water,energy savings,cost-effective investment
更新于2025-09-16 10:30:52
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LED Boost Driver Topologies for Low Voltage DC Distribution Systems in Smart Structured Buildings
摘要： Most of the loads connected to the existing AC distribution system operate with low voltage DC power. Hence, there is a requirement to convert AC into DC power. Often there are many inefficiencies associated with AC to DC power conversion. To enhance the energy conservation, low voltage DC distribution system (LVDCDS) is suggested in this paper. Forty percent of the total power consumed in India is by lighting loads which make use of DC power. LVDCDS is an ideal choice to power lighting loads in residential and commercial buildings. This paper presents a detailed study of four different single stage, interleaved, non-isolated light emitting diode (LED) drivers for lighting load. All the topologies are developed in hardware and tested experimentally with controller implementation to provide a constant power of 70 W to power LED lights in the campus building. The installation cost, payback period, and energy savings for the converters connected to LVDCDS are analyzed and discussed in particular.
关键词： digital controller,LED boost drivers,energy savings,energy efficient building
更新于2025-09-11 14:15:04
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Feasibility Study and Impact of Daylight on Illumination Control for Energy-Saving Lighting Systems
摘要： The main goal of energy conservation should be reducing the consumption of energy resources. Due to energy and environmental concerns in recent years, to reduce energy consumption in a lighting system, which has been one of the prime targets of energy saving, daylighting has been investigated and has become one of the energy-efficiency techniques widely applied in buildings. This paper presents an analysis of T5 fluorescent luminaire lighting control using daylight in a building. The study is conducted in two parts; simulation of a lecture room using the daylighting function of the DIALux program is performed to estimate the effect of daylighting on a task area (workplane). Another part is an experimental setup to evaluate the performance of a lighting control unit that is installed for a T5 fluorescent luminaire with a dimmable electronic ballast. The efficiency of the lighting control in term of illumination on the task area and energy consumption are also evaluated and compared with the standard case. The simulation results show that daylighting increases illuminance on a task area, especially on the window side, so the lighting system can significantly reduce its power consumption compared with a standard case (without lighting control). The experimental result shows that upon installing the lighting control with daylighting, both the average illuminance and the energy consumption in each time period are decreased compared with in the standard case. Lighting control with daylighting tries to set the average illuminance on a task area to less than 500 lux, corresponding to the amount of daylight passing through window shutters. The obtained results are useful for the design of a T5 fluorescent luminaire with lighting control using daylighting in a building lighting system for energy efficiency and reducing energy consumption, including the average illuminance on the task area, according to a relevant standard.
关键词： lighting system,fluorescent lamp,energy savings,daylight,illuminance
更新于2025-09-10 09:29:36
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Rapid Pulsed Light Sintering of Silver Nanowires on Woven Polyester for personal thermal management with enhanced performance, durability and cost-effectiveness
摘要： Fabric-based personal heating patches have small geometric profiles and can be attached to selected areas of garments for personal thermal management to enable significant energy savings in built environments. Scalable fabrication of such patches with high thermal performance at low applied voltage, high durability and low materials cost is critical to the widespread implementation of these energy savings. This work investigates a scalable Intense Pulsed Light (IPL) sintering process for fabricating silver nanowire on woven polyester heating patches. Just 300 microseconds of IPL sintering results in 30% lesser electrical resistance, 70% higher thermal performance, greater durability (under bending up to 2 mm radius of curvature, washing, humidity and high temperature), with only 50% the added nanowire mass compared to state-of-the-art. Computational modeling combining electromagnetic and thermal simulations is performed to uncover the nanoscale temperature gradients during IPL sintering, and the underlying reason for greater durability of the nanowire-fabric after sintering. This large-area, high speed, and ambient-condition IPL sintering process represents an attractive strategy for scalably fabricating personal heating fabric-patches with greater thermal performance, higher durability and reduced costs.
关键词： Intense Pulsed Light (IPL) sintering,woven polyester,personal thermal management,energy savings,silver nanowires
更新于2025-09-10 09:29:36
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Daylight Spectrum Index: A New Metric to Assess the Affinity of Light Sources with Daylighting
摘要： The current scenario of colorimetry shows a wide variety of different metrics which do not converge in the assessment of the color rendering of light sources. The limitations of the Color Rendering Index have promoted the emergence of new metrics, such as the Color Quality Scale. As in the case of the previous metric, these new concepts are based on the analysis of the deviation of different color samples in a color space, contrasting the results with those obtained with a light source reference, which can vary depending on the color temperature. Within this context, the Daylight Spectrum Index is proposed. This new concept aims to determine the affinity with daylighting of electric light sources, comparing the resulting spectral power distributions of the lamps studied and that observed under natural light. The affinity of an electric light source with daylighting allows for lower energy consumption due to the better performance of human vision. The new metric proposed is evaluated following the results obtained from 80 surveys, demonstrating the usefulness of this new concept in the quanti?cation of color rendering of LED lamps and the affinity of electric light sources with daylighting.
关键词： light spectra,light sources,color rendition,colorimetry,energy savings,daylighting
更新于2025-09-04 15:30:14