Operating Control of Photobiological Safety of LED Luminaires

2019 ◽  
pp. 37-42
Author(s):  
Alexander V. Karev ◽  
Dmitry S. Dmitry S. Lyoskin
Keyword(s):  
White Light ◽  
Laboratory Testing ◽  
Risk Level ◽  
International Electrotechnical Commission ◽  
Special Equipment ◽  
Experimental Assessment ◽  
Russian Market ◽  
Colour Temperature ◽  
Safety Requirements ◽  
Hazard Level

Photobiological safety has become an integral part of safety requirements to general use luminaires including during certification. In that context, the necessity to control this parameter in the course of designing and manufacturing of lighting devices (luminaires) as well as sales of imported devices in the Russian market has increased dramatically. In the meantime, experimental assessment of this indicator in accordance with requirements of IEC62471Р¦2013 standard is rather hard requiring application of special equipment and certified personnel. This circumstance makes operating control of photobiological safety by manufacturers almost impossible. The foreign practice of application photobiological safety-related standards confirms this problem. In 2014, International Electrotechnical Commission has published a handbook for application of the standard provisions, which significantly simplifies the procedure of such assessments: IEC/ TR62778:2014. The article describes the method of application of provisions of this handbook as an operating tool in the course of development of general use LED luminaires with white light LED. The provisions consist of assessment of hazard level in terms of illuminance in the area of the most possible location of a spectator and colour characteristics of a light source. A calculation method of risk level assessment on the basis of spatial light distribution and correlated colour temperature of LED luminaires is proposed, the results of calculations are compared with the results of laboratory testing.

Evaluation of a daylight-responsive, iterative, closed-loop light control scheme

2019 ◽  
Vol 52 (2) ◽  
pp. 257-273
Author(s):  
PK Maiti ◽  
B Roy
Keyword(s):  
White Light ◽  
Laboratory Testing ◽  
Closed Loop ◽  
Light Emitting Diode ◽  
Light Control ◽  
In Situ Testing ◽  
Light Emitting ◽  
Colour Temperature ◽  
Control Scheme

In this paper an iterative, closed-loop light control scheme is proposed and evaluated by a white light emitting diode-based, daylight-responsive luminaire to follow the time-varying pattern of correlated colour temperature and illuminance of a daylight scene. The proposed control scheme functions primarily with the response signals of two RGB colour sensors, viz., a daylight sensor to monitor the daylight scene at the window plane and an internal light sensor to monitor the light scene created by the test white light emitting diode luminaire. The control scheme controls the lumen delivery of individual light emitting diode arrays of the test luminaire by adjusting the duty cycles to follow the instantaneous correlated colour temperature of daylight and at the same time to respond to the variation of window plane illuminance in the reverse pattern. Evaluation is conducted by laboratory testing and in situ testing. The maximum deviations in correlated colour temperature, illuminance and chromaticity from the required values under laboratory testing and in situ testing are found to be [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text], [Formula: see text] respectively, which establish the acceptable performance of the proposed iterative light control scheme.

scholarly journals Colour Temperature Tuning to Improve Efficacy of White Light

2016 ◽  
Vol 24 ◽  
pp. 1186-1193 ◽  
Author(s):  
Saijo Prathap ◽  
Sonia Sunny ◽  
Aju S. Nair
Keyword(s):  
White Light ◽  
Colour Temperature ◽  
Temperature Tuning

scholarly journals Risk analysis of landslide as a basis of mitigation plan: a case study of Mangunan Village, Bantul, Indonesia

2021 ◽  
Vol 933 (1) ◽  
pp. 012034
Author(s):  
S Aminatun ◽  
Jafar ◽  
A U Jamal
Keyword(s):  
High Capacity ◽  
Secondary Data ◽  
Primary Data ◽  
Risk Level ◽  
Eastern Region ◽  
Infrastructure Development ◽  
Risk Map ◽  
Risk Zone ◽  
Capacity Level ◽  
Hazard Level

Abstract When rainy season comes, in Mangunan Village, landslide occurs frequently. Mangunan is one of the villages in Bantul District that possesses high intensity of landslide events. Located in a contoured hilly area on the eastern region of Bantul District is one of the reasons. This study aims to analyze the risk of landslide in Mangunan by detailing the risk map, which constitutes a general risk map, and to identify the number of households that are currently residing in each risk-zone area. In this study, we applied a descriptive method that combined both qualitative and quantitative approaches in order to generate a good depiction of settlements in each risk-zone area. The data of this study can be classified into two categories, primary and secondary data. Primary data were obtained from field activities such as interviews and field documentation. Meanwhile, secondary data were obtained from archives, notes, or reports from related agencies. The results of this study are: 1) the number of settlements that are located in high- and medium-vulnerability areas are 143 and 12, respectively; 2) Mangunan Village possesses high hazard level, medium to high vulnerability level, and high-capacity level which means the village has medium to high risk level; 3) Recommendations of infrastructure development for landslide mitigation.

Laboratory testing and in situ behaviour of peat as embankment foundation

1984 ◽  
Vol 21 (2) ◽  
pp. 322-337 ◽  
Author(s):  
G. Lefebvre ◽  
P. Langlois ◽  
C. Lupien ◽  
J.-G. Lavallée
Keyword(s):  
Pore Pressure ◽  
Laboratory Testing ◽  
Lateral Displacement ◽  
Laboratory Data ◽  
Constant Load ◽  
Log P ◽  
Creep Tests ◽  
Special Equipment ◽  
Fibrous Peat ◽  
Pore Pressure Response

Intact block samples of fibrous peat have been obtained using special equipment from two different sites in the James Bay territory in Quebec. Instrumented test fills were subsequently built at those two sites and the observed behaviour was used to check the laboratory data. The laboratory testing program has included standard 24 h incremental tests and stage creep tests where constant loads were applied for periods of about 30 d. Pore pressure and direct permeability measurements were conducted in most of the tests.The tests have been interpreted using the classical e − log p curves or the tangent modulus approach. The evaluation of compression with time under a constant load has allowed the distinction between primary and secondary consolidation. A certain lag in pore pressure response has been observed and related to incomplete saturation. The coefficient of permeability decreases rapidly with compression as indicated by direct measurements and pore pressure dissipation.The comparison with field observation shows that the 24 h incremental oedometric compression test permits a reasonable prediction of the average settlements at the end of primary consolidation provided the lateral displacement during construction is small. It also shows that the secondary compression observed in the field is about twice what was observed in the laboratory but both show a linear relation with the logarithm of time.Keywords: peat, sampling, compressibility, consolidation, secondary consolidation, permeability, laboratory tests, field behaviour.

A white–cyan-red LED system for low correlated colour temperature lighting

2015 ◽  
Vol 49 (3) ◽  
pp. 343-356 ◽  
Author(s):  
M Chakrabarti ◽  
A Thorseth ◽  
DD Corell ◽  
C Dam-Hansen
Keyword(s):  
White Light ◽  
Colour Temperature ◽  
White Leds ◽  
Geometrical Modelling ◽  
Red Led ◽  
Colour Gamut ◽  
Museum Display ◽  
Colour Rendering ◽  
Red Leds ◽  
Planckian Locus

A white LED complemented by cyan and red LEDs is a good candidate for achieving high colour rendering at low correlated colour temperatures. This is usually very difficult with commercially available white LEDs. In addition, the system is able to replace incandescent lighting in many applications; for example, the lighting for museum display cases. To investigate and optimize the colour and light distribution properties, both spectral and geometrical modelling are used. Mapping of the possible combinations of LEDs is used to locate the optimal solutions within the colour gamut, with emphasis on chromaticity and colour rendering indices. A geometric optical model is used to design and optimize the homogeneity of the colour and light intensity distribution as a function of angle. The resulting system produces diffused homogeneous white light with a tunable correlated colour temperature from 2000 K to 2400 K. Within this range the white light is characterized by a high general colour rendering index (Ra > 90), special colour rendering indices for saturated red objects (R9 > 85), and low chromaticity distance (Duv) from the Planckian locus (Duv < 2 × 10−3).

scholarly journals Risk Assessment of Civil Aircraft during Operation

2020 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Risk Assessment ◽  
Failure Modes ◽  
System Structure ◽  
Assessment Process ◽  
Risk Level ◽  
Failure Risk ◽  
System Risk ◽  
Hazard Level ◽  
Aircraft System

In this chapter, the risk assessment methods for aircraft system, structure, and aeroengine are investigated. For the aircraft system risk assessment, the probability level is divided into probable, improbable, and extremely improbable, and the hazard level of the failure condition is divided into minor, major, and catastrophic. Using Weibull analysis and Bayesian method to analyze the aircraft operation data, the risk level of aircraft system can be determined by combing methods provided in AC 25.1309-1A. For the aircraft structure risk assessment, the probability fracture mechanics approach can be used to determine the structure failure risk based on the data of material properties, environment, inspection, and so on. For the aeroengine risk assessment, the methods for classification of failure risk level, determination of hazard ratio, and calculation of the risk factor and risk per flight are given. The risk assessment process for aeroengine multi-failure modes based on the Monte Carlo simulation is presented to predict the occurrence of the failure and assess the failure risk.

scholarly journals Workplace Biological Risk Assessment: Review of Existing and Description of a Comprehensive Approach

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 741 ◽  
Author(s):  
Sarah Burzoni ◽  
Philippe Duquenne ◽  
Gautier Mater ◽  
Luc Ferrari
Keyword(s):  
Health And Safety ◽  
Qualitative Evaluation ◽  
Risk Level ◽  
Biological Risk ◽  
Adverse Health Effects ◽  
Occupational Setting ◽  
Hazard Level ◽  
Exposure Indicators ◽  
Pathogenic Agents ◽  
Hazard Levels

Biological risks potentially affect workers in multiple occupational sectors through their exposure to pathogenic agents. These risks must be carefully assessed to prevent adverse health effects. This article identifies and critically analyzes approaches that manage the qualitative evaluation of biological risk (EvBR) as part of occupational health and safety prevention, for which no standard method yet exists. Bibliographic and computing references were searched to identify qualitative EvBR approaches, which were then analyzed based on defined criteria, such as the risks studied and the type of assessment. Approaches proposing the most representative types of assessment were analyzed. EvBR approaches in an occupational setting were identified in 32 sources. “Workstation analysis” combined with “assessment by risk level” were the most common approaches. The predominant risk descriptors (RDs) were defined in a characterized and quantifiable way, and a variety of hazard levels and exposure indices were created. Overall, the risk was determined by summing or multiplying the hazard level and exposure indicators. The results confirmed that no methodological consensus currently exists regarding the EvBR and no approach has yet been described that integrates all the parameters to allow for a full assessment of biological risk. Based on the detailed analysis of the existing data, the present paper proposes a general approach.

Interactive effect of illuminance and correlated colour temperature on colour preference and degree of white light sensation for Chinese observers

Optik ◽  
2020 ◽  
Vol 224 ◽  
pp. 165675
Author(s):  
Yu Wang ◽  
Qiang Liu ◽  
Wenyu Gao ◽  
Michael R. Pointer ◽  
Zheng Huang ◽  
...  
Keyword(s):  
White Light ◽  
Interactive Effect ◽  
Colour Preference ◽  
Colour Temperature

scholarly journals Low-Cost Extra-Low Voltage LED Dimmer for Tuneable White Lighting

2019 ◽  
Vol 25 (3) ◽  
pp. 43-49
Author(s):  
Roman Hrbac ◽  
Tomas Mlcak ◽  
Vaclav Kolar ◽  
Tomas Vantuch
Keyword(s):  
White Light ◽  
Low Voltage ◽  
Low Cost ◽  
Light Output ◽  
Electrical Performance ◽  
Light Sources ◽  
Colour Temperature ◽  
Lighting Systems ◽  
Module Efficiency ◽  
The Right

The colour appearance of light sources has a major impact on how people perceive space. With LED illumination lighting, the colour output can be tuned to virtually any perceivable colour, including any hue of white light. It has been established that the right shade of white light during the 24-hour day cycle has a positive effect on the human body's biological system. For this reason, it is very important to focus on the development and application of new lighting systems that have dynamically variable light outputs in order to imitate the sunlight. Circadian regulation is most responsive to short-wavelength light (460 nm = blue colour). This paper describes the development of a low-cost extra-low voltage LED dimmer for tunable white lighting systems aiming to achieve maximum electrical performance and light-output. This dimming module has two independent LED control channels and allows for a variable colour temperature control from warm white to cold white light. Experimental results of the dimming module efficiency measurements, correlated colour temperature (CCT), colour rendering index (CRI), illuminance and power consumption of the luminaire depending on the duty cycle for different control frequencies (200 Hz, 1.5 kHz, 5 kHz, 10 kHz and 20 kHz) are presented. The paper further describes the principle of creating control curves for an independent regulation of correlated colour temperature and illuminance. In the form of a table, the control curve outputs may be uploaded into a microcontroller. The paper details the construction, function and the advantages of this LED dimmer prototype.

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