scholarly journals A Simple Designed Lens for Human Centric Lighting Using LEDs

2020 ◽  
Vol 10 (1) ◽  
pp. 343 ◽  
Author(s):  
Duong Thi Giang ◽  
Thuy Linh La ◽  
Tran Quoc Tien ◽  
Pham Hong Duong ◽  
Quang Cong Tong
Keyword(s):  
Low Cost ◽  
Visual Comfort ◽  
Human Beings ◽  
High Uniformity ◽  
Freeform Optics ◽  
Irradiation Angle ◽  
Indoor Lighting ◽  
Ray Tracing Simulation ◽  
Natural Characteristics ◽  
Newborn Jaundice

Light is generally important for human beings. Visible light supports vision and can modify circadian rhythm, and together with invisible light at longer or shorter wavelength can also make either a direct or indirect impact on human biological and mental health. For medical applications, several studies have shown success in using light to fasten the skin regeneration in burns and to cure diseases such as newborn jaundice. In daily life, an appropriate amount and time exposure to certain types of light can result in rising of alertness and mood improvement, which leads to noticeable growth in one’s productivity. Therefore, human centric lighting can modify lighting factors to make the best of the natural characteristics of light. The seek an ideal indoor lighting system is widely carried out not only by scientists but also by architects. A qualified luminaire is considered by many factors, including luminous productivity, visual comfort and expenses; meanwhile, the idealization of illuminance is also constructed in many ways, such as widening the lamp’s surface area, changing of luminaire’s positions and applying different methods to illuminate a surface. Approaching these problems, our idea is to study the uplighting method and freeform optics using low-cost acrylic lenses. By changing lens shape and optimizing the factors which affect the illuminance such as the irradiation angle and the distance between the luminaire and the reflection surfaces, we find the most effective lens and its peaks due to each factors using the ray-tracing simulation to obtain results concerning high uniformity of illumination.

A field study of fluorescent and LED classroom lighting

2016 ◽  
Vol 50 (4) ◽  
pp. 631-650 ◽  
Author(s):  
N Gentile ◽  
T Goven ◽  
T Laike ◽  
K Sjoberg
Keyword(s):  
Secondary School ◽  
Field Study ◽  
Energy Savings ◽  
Electricity Consumption ◽  
Visual Comfort ◽  
Lighting System ◽  
Upper Secondary ◽  
Lighting Systems ◽  
Indoor Lighting ◽  
Academic Year

Indoor lighting is facing a massive retrofit to LED lighting. Research is needed to assess whether LED-based lighting can promote energy efficiency, boost visual comfort and support biological functions. This field study considered the lighting of four identical classrooms in an upper secondary school in Helsingborg, Sweden. Two classrooms were fitted with state-of-the-art ceiling pendants containing T5 fluorescent tubes and that had a direct/indirect light distribution (the control rooms). The other two classrooms were fitted with an experimental LED indirect lighting system (the experimental rooms). In the classrooms, 72 students aged 17–18 years performed their usual educational activities over a whole academic year. The light environment, electricity consumption, and students’ mood, light perception and saliva cortisol concentration were monitored. The two lighting systems produced only marginal differences. Overall, the experimental rooms were slightly preferred but achieved only small energy savings due to high parasitic losses.

Effects of Indoor Lighting on Occupants’ Visual Comfort and Eye Health in a Green Building

2010 ◽  
Vol 20 (1) ◽  
pp. 75-90 ◽  
Author(s):  
Taeyon Hwang ◽  
Jeong Tai Kim
Keyword(s):  
Psychological Health ◽  
Green Building ◽  
Personal Characteristics ◽  
Visual Display ◽  
Visual Comfort ◽  
Visual Display Terminal ◽  
Eye Health ◽  
Shading Devices ◽  
Shading Device ◽  
Indoor Lighting

This study investigated the effects of indoor lighting on occupants’ visual comfort and eye health and to contribute to the management and maintenance of buildings. The illuminance of the working plane and windows at Samsung Corporation Headquarters were measured, and 2744 healthy occupants of Samsung Corporation were surveyed regarding the indoor lighting environment via the company’s intranet for 1½ years. This building was certified with the highest ranking by Korea’s Green Building Council. The cumulative data reflected the management and maintenance of the building, such as screen-type shading devices automatically controlled by seasons and time, improvement of visual display terminal glare by the veiling reflection on monitors, efficiency of artificial lighting arrays, and so on. The data were analysed for occupants’ visual comfort and eye health. The result showed that daylighting could improve the occupants’ psychological health and productivity. The screen-type shading device could intercept direct sunlight and reduce annoyance glare. However, the indoor lighting and visual environment of the building were poor. After examining the questionnaire feedback concerning improvements, the occupants’ annoyance ratio was significantly reduced, and approximately 5% of the occupants’ annoyance ratio was deemed to be caused by personal characteristics related to the lighting of the environment.

A simple design of uniform LED illumination using catadioptric collimator and freeform lenslet array

2021 ◽  
pp. 147715352110524
Author(s):  
DT Vu ◽  
H Vu ◽  
S Shin ◽  
NM Kieu ◽  
TQ Tien ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Light Emitting Diode ◽  
Optical Path Length ◽  
Light Emitting ◽  
Simple Strategy ◽  
Area Of Interest ◽  
Lenslet Array ◽  
Freeform Optics ◽  
Receiver Plane ◽  
Indoor Lighting

We introduce a compact lenslet array principle that takes advantage of freeform optics to deploy a light distributor, beneficial for highly efficient, inexpensive, low energy consumption light-emitting diode (LED) lighting system. We outline here a simple strategy for designing the freeform lens that makes use of an array of the identical plano-convex lenslet. The light is redistributed from such lenslet, hinging on the principle of optical path length conservation, and then delivered to the receiver plane. The superimposing of such illumination area from every lenslet occurs on the receiver plane, in which the non-uniform illumination area located in the boundary should have the same dimension as the size of the freeform lenslet array. Such an area, insofar, is negligible due to their small size, which is the crux of our design, representing a large departure from the former implementations. Based on simulations that assess light performance, the proposed design exhibited the compatibility for multiple radiation geometries and off-axis lighting without concern for the initial radiation pattern of the source. As simulated, the LED light source integrated with such proposed freeform lenslet array revealed high luminous efficiency and uniformity within the illumination area of interest were above 70% and 85%, respectively. Such novel design was then experimentally demonstrated to possess a uniformity of 75% at hand, which was close to the simulation results. Also, proposed indoor lighting was implemented in comparison with the commercial LED downlight and LED panel, whereby the energy consumption, number of luminaires and illumination performance were assessed to show the advantage of our simplified model.

scholarly journals Microbiological Quality of Drinking Water in Sachets Sold in the City of Yaoundé in Cameroon: Tests of Sensitivity to the Antibiotics of Bacteria Isolated

2020 ◽  
Vol 8 (1) ◽  
pp. 27
Author(s):  
Nguepidjo Gilbert ◽  
Kapso Tchouankep Mireille ◽  
Ngong Ankiambom Innocent ◽  
Tonmeu Douyong Chimène Sandrine ◽  
Enoka Patrice ◽  
...  
Keyword(s):  
Drinking Water ◽  
Low Cost ◽  
Bacterial Species ◽  
Microbiological Quality ◽  
Positive Culture ◽  
Human Beings ◽  
Salmonella Spp ◽  
Cross Sectional ◽  
The City

Water is the basic drink for human beings and drinking water in sachets is very popular because of its relatively low cost and availability. The aim of this study is to determine the bacteriological profile of sachet drinking water sold in the city of Yaounde. It was a descriptive cross-sectional study covering the period from March to June 2019, carried out in the application laboratory of ETMS-Yaounde. A total of 230 samples of drinking water in sachets purchased in different markets in the city of Yaounde were analyzed using Mac Conkey's flooding method. The identification was done on the API 20 E Gallery and the susceptibility test on Mueller Hinton media. The size of the sample was 230 packaged sachet drinking water and 213 of the 230 revealed 92% of positive culture of germs, and only 17 samples gave a negative culture, at a percentage of 8% of isolated germs. The isolated bacterial species and their respective abundances in samples were Enterobacter gergoviae (3%), Klebsiella pneumoniae (5%), Proteus mirabilis (5%), Serratia fonticola (5%), Salmonella choler arizonae cloacae (8%), Salmonella spp. (8%), Enterobacter cloacae (10%), Staphylococcus aureus (10%), Pseudomonas aeruginosa (18%) and Staphylococcus epidermidis (28%). All these tested germs were resistant to Amoxicillin and Erythromycin and 70% of tested germs were sensitive to Gentamycin. Overall, the results revealed poor microbiological quality of these waters. This exposes consumers to health risks, and it is important to inform and sensitize consumers about the risks involved, to educate producers and to control their activities by the health services.

New Type of Distributed Biomass Combustion Device Necessity and Feasibility in China

2011 ◽  
Vol 383-390 ◽  
pp. 4013-4016
Author(s):  
Chang Le Pang ◽  
Li Chen ◽  
Ren Jie Dong
Keyword(s):  
Rural Areas ◽  
High Efficiency ◽  
Low Cost ◽  
Biomass Combustion ◽  
Combustion System ◽  
Human Beings ◽  
New Type ◽  
Energy Products ◽  
The Ideal ◽  
Commercial Energy

Worldwide changes in climate and environment forced us human beings to seek for alternatives to replace commercial energy products like coal and petroleum. However, there have some difficulties to promote commercial energy products in China’s rural areas and newly urbanized areas. Biomass combustion system will become one of the ideal devices for such areas in a period of time. It is necessary to develop new types of biomass combustion system consisting of gasification or Semi-Gasification and combustion units so that it can provide high efficiency and low cost for household purposes.

The Influence of Internal Coloured Surfaces on the Circadian Efficiency of Indoor Daylight

2016 ◽  
Vol 861 ◽  
pp. 493-500 ◽  
Author(s):  
Peter Hartman ◽  
Lucia Maňková ◽  
Peter Hanuliak ◽  
Michal Krajčík
Keyword(s):  
Seasonal Affective Disorder ◽  
Visual Comfort ◽  
Human Beings ◽  
Light Stimulation ◽  
Light Spectrum ◽  
Efficiency Function ◽  
Health And Wellbeing ◽  
Internal Surfaces ◽  
The Difference

The discovery of circadian stimulation by daylight has changed our understanding of the important effect the daylight has on our health and wellbeing. The new medical facts that emerged during the last decade have proven that a long-term absence of circadian light stimulation may be associated with sleep disturbance, tiredness and increased incidence of chronic depression, bipolar disorder, and seasonal affective disorder. The reason is the difference between the visual and biological (circadian) response to light and how it is being perceived by human beings: while the visual perception represented by the luminous efficiency function peaks at the wavelength of 555 nm, the circadian photoreception curve peaks in the blue light spectrum at ~450 nm. The primary circadian stimulation by daylight depends on the properties of light impinging on the retina. An experimental study was designed to quantify the effect of internal coloured surfaces on our circadian stimulation by daylight. Four identical models of a standard office were manufactured, equipped by wallpapers of different colours, and exposed to daylight. Illuminance and spectral distribution of light were measured at different positions along the room and the potential circadian stimulation was evaluated by an established model. The measurements have proven that although the visual comfort may be satisfactory, circadian stimulation may be inhibited, especially when room´s surfaces are yellow. Thus, proper choice of internal surfaces´ colours is important to prevent the potential negative health consequences.

scholarly journals COASTAL MAPPING AND KITESURFING

2018 ◽  
Vol XLII-4/W8 ◽  
pp. 3-10
Author(s):  
J. Barde ◽  
S. Bonhommeau ◽  
E. Chassot ◽  
B. Motah
Keyword(s):  
Data Collection ◽  
Data Storage ◽  
Low Cost ◽  
Environmental Parameters ◽  
Ocean Dynamics ◽  
Human Beings ◽  
Marine Animals ◽  
Coastal Mapping ◽  
Archival Tags ◽  
Recreational Vessels

<p><strong>Abstract.</strong> Collecting data on aquatic biodiversity is very challenging because of the difficulty to access underwater ecosystems. Over the years, field surveys have become easier and cheaper with the development of low cost electronics. Commercial and recreational vessels, including sailboats, can now substantially complement expensive scientific surveys and arrays of observation buoys deployed across the world oceans (Pesant et al., 2015, Karsenti et al., 2011). Meanwhile, a large variety of marine animals such as birds, mammals, and fish have become data collection platforms for both biological and environmental parameters through the advent of archival tags. It becomes obvious that data collection in coastal and high seas will become more popular and that citizen will play a growing role in acquiring information on ocean dynamics (physical, chemical and biological parameters). However, currently, very few attempts have been made to use Human beings as observation platforms. In this paper we describe large datasets (more than 200,000 pictures) that have been recently collected along the coast of Mauritius by using popular and cheap platforms such as kite surf and Stand Up Paddle. We describe the characteristics of the data collected and showcase how they can be geolocated and used to complement remote sensing and mapping in order to drastically extend the current scope of “old school” fieldwork. We point out some of the main limitations encountered which need to be addressed to foster this citizen science approach such as data storage and transmission, deep learning to automate image recognition. The methods are all based on open source softwares.</p>

scholarly journals Low Cost High Intensity LED Illumination Device for High Uniformity Laboratory Purposes

2020 ◽  
Author(s):  
Carmine D' Alessandro ◽  
Davide De Maio ◽  
Teresa Mundo ◽  
Marilena Musto ◽  
Franscesco Di Giamberardino ◽  
...  
Keyword(s):  
Power Density ◽  
High Intensity ◽  
Low Cost ◽  
White Led ◽  
Minimum Volume ◽  
Uniform Illumination ◽  
Research Fields ◽  
High Uniformity ◽  
Density Map ◽  
Led Arrays

Uniform illumination is a key requirement in different research fields. However, this requirement is often difficult to achieve when high intensity is required at the same time. Recent advancements in LED lamps allow nowadays for compact and economical solutions. In this work we present a suitable solution for various laboratory purposes requiring stable, uniform and high intensity illumination. The system is composed of four identical high power white LED arrays of 30 mm diameter each, placed on a supporting and cooling structure having a minimum volume of 26 cm x 26 cm x 8 cm. A numerical model has been developed, based on a ray tracing software, in order to simulate the performances. These have then been experimentally validated with measurements of the power density map, carried out with a 1% uncertainty pyranometer. Data show that the built system is very stable over time and provides an illumination uniformity higher than 98%, on a surface of 50 mm radius, which reduces to 95% on a surface of 75 mm radius. The power density can be adjusted in the 390-1360 W m-2 range, not affecting uniformity.

Sign in / Sign up

Export Citation Format

Share Document