Qi Yao

Qi Yao
Fudan University · Academy for Engineering and Technology

Doctor of Philosophy

About

32
Publications
10,589
Reads
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116
Citations
Introduction
Spectral optimization, Healthy lighting, Light pollution

Publications

Publications (32)
Article
The vast amount of reflectance information obtained from the hyperspectral imaging devices offers great opportunities for investigating the function and structure of human tissue. However the captured hyperspectral data often contain various noises due to the intrinsic imperfection of associated electrical and optical imaging components. This work...
Article
A numerical approach has been proposed to identify bands for optimally estimating the concentration of three types of viable chromophores within biological tissue. The bands are determined according to the condition number of absorption matrix associated with the attenuation coefficients of chromophores. The effectiveness of different sets of selec...
Article
Purpose Dental caries detection, especially the accurate detection of early caries, facilitates prompt interventions. It is reasonably common to use fluorescence imaging for classification and evaluation of caries, but lacks a quantitative, precise and easy-to-use characterization for practical applications. In this study a quantitative approach fo...
Article
Full-text available
Several models on the circadian effect have been applied to indoor circadian lighting design, but applications in road lighting have not yet been clarified. Based on existing models and circadian research, we examined equivalent melanopic lux (EML), circadian light (CLA), and circadian stimulus (CS) representing the circadian effect and the S/P rat...
Article
Full-text available
In this work, we investigated the luminous and melanopic efficiency of the radiation (LER/MER) performances of phosphor-converted LEDs (PC LEDs) with tunable spectral characteristics, namely peak wavelength, full width at half maximum (FWHM), and emission intensity. We constructed theoretical PC LED spectra based on the characteristics extracted fr...
Article
Full-text available
In this work, we investigated 39 façade lighting displays, all of which consisted of tri-chromatic light sources, namely blue-, green-, and red- light units, in Shenzhen, China. We extracted the spectral characteristics of the mean peak wavelength/full-width at half-maximum, and proposed universal spectral models. We further established the 'chroma...
Article
With the increasing understanding of light's non-visual impact on human circadian system, applying circadian daylighting in buildings becomes attractive. The successful adoption of circadian daylighting requires a considerable amount of light incident at the eyes without causing discomfort glare. Therefore, developing daylighting strategies that ca...
Article
Full-text available
We investigate the spectral power distributions of 54 phones (33 measured experimentally in default text mode and 21 downloaded from the web) and estimate the mean ± std. dev. of the luminous efficiency of radiation, melanopic efficiency of radiation, and melanopic/photopic ratio as 287 ± 13 lm/W, 303 ± 26 blm/W, and 1.06 ± 0.13, respectively. We e...
Article
In this work, we synthesized a sun-like light source with tri-chromatic broad spectra, composed of light source units with single-peak 435-nm carbon quantum dots (QDs) and 695-nm perovskite QDs, and dual-peak 510- and 590-nm Ag-doped InP QDs, referencing CIE standard illuminants D50 and D65. Based on a spectral angle measure approach, we adopt the...
Article
Full-text available
Despite the fact that a 2-degree spectral sensitivity curve (SSC) is extensively used in scientific research and relevant applications, the choice between the 10-degree or the 2-degree photopic SSCs in practical applications for the calculation of scotopic/photopic ratios (S/P ratios) depends on actual needs. We examined S/P ratios for more than 30...
Conference Paper
Detecting pavement irregularities that might lead to a fall if not seen in sufficient time is one of the critical visual tasks of pedestrians. Experiments have been conducted to determine how the detection of peripheral objects, at mesopic light levels, is affected by light level and spectrum, leading to proposals for new guidance. As with all expe...
Article
This study attempts to quantify and optimize the luminous efficacy of radiation (LER) of tri-chromatic light sources in both photopic and mesopic visions. A new chromaticity-guided rather than spectrum-guided optimization approach is provided. LER contour maps formed by the gamut area of the three light source units are drawn in the chromaticity di...
Article
To determine mesopic luminance for a given photopic luminance and scotopic/photopic (S/P) ratio, the Commission Internationale de l’Eclairage (CIE) recommended system utilizes an equation. Whilst being accurate, it requires several iterations to achieve a stable result and requires the use of an adaptation coefficient. This article proposes an alte...
Article
Full-text available
Big lighting data are required for evaluation of lighting performance and impacts on human beings, environment, and ecology for smart urban lighting. However, traditional approaches of measuring road lighting cannot achieve this aim. We propose a rule-of-thumb model approach based on some feature points to reconstruct road lighting in urban areas....
Article
The scotopic/photopic ratio (S/P) is a parameter that may be considered in the design of road lighting. This paper compares the S/P ratio and correlated colour temperature (CCT) for 297 light source spectra identified in IES Technical Memorandum TM-30-15 to test the assumption that higher S/P ratios demand higher CCTs. The results suggest that, for...
Article
Full-text available
In this study, we conducted a combined examination of the photometric and colorimetric performance of tri-chromatic light sources, which are synthesized by three kinds of light-source units, by transferring their photometric performance to chromaticity diagrams. Contour maps of three photometric performances, which are within a triangle gamut-area...
Article
Full-text available
In this paper, a diagram illustrating the combined circadian effect and mesopic vision effect caused by cirtopic, scotopic, and photopic photoreceptors, i.e., a vision effect diagram, was established using a chromaticity diagram based on $L$, $M$, and $S$ cone cells for reference. The characteristics of the vision effect diagram were studied, and m...
Article
Full-text available
This study aimed to identify how different types of uniformity indicators function to evaluate the uniformity of lighting, such as the minimum-to-average ratio (Min:Avg), the coefficient of variance (CV), entropy uniformity (EU, introduced in the article), and a pattern vision-based indicator (UHVS). Two experiments, a pair-wise comparison and a se...
Article
Full-text available
Due to the lack of quantitative evaluation of lighting efficiency and lack of theoretical guidance on spectrum mechanism, there exists huge energy consumption in landscape lighting. This study aims to quantify landscape lighting effect and define efficiency evaluation indicator by studying the relationship between light sources' spectrum and object...
Article
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This paper studies spectrum optimization of four-package LEDs to improve performance of light sources with respect to properties such as luminous efficacy and colour rendering as well as luminous efficacy of radiation under photopic and mesopic conditions and circadian efficacy of radiation for non-visual biological effects. For colour mixing of fo...
Article
Full-text available
Curve fitting and lookup table methods based on vector relationships are proposed to compute dominant wavelength (DW), which is used to characterize hue. A curve-fitting method using a DW–angle relationship is simple but not very accurate, with an error of about 1 to 2 nm. A lookup table method is proposed for higher precision. The methods have bee...
Article
Full-text available
Two experiments involving facial recognition and color identification have been done to evaluate the performance of road lighting with HPS and CMH. 48 subjects took part in the facial recognition experiment, and 43 in the color identification experiment, aged 20 to 40. In the facial recognition experiment we used 8 cards with different head portrai...
Article
The lighting types are classified into low position inverse lighting type, low position forward lighting type, high position inverse lighting type and high position forward lighting type. The lighting efficiency analysis and experimental verification of all the four lighting types were done in the 2-dimensional plane and 3-dimensional space with di...
Article
The morphological characteristics of urban landscape lighting is analyzed. A color-brightness system is summarized as color parameter, light shape parameter, transformation parameter. Characteristic parameters of a color-brightness system are defined, and eigenvector and incidence matrix are induced for describing relationships among different para...
Article
The luminous efficiency do make four impact factors confused such as existing of dissipated light, ability for transmission of lighting sources, distortion of visual effects and different values of power choosing during the luminous efficiency comparison under its current definition. In this paper, the equivalent luminous efficiency was introduced...
Article
Retinal illuminance was the effective illuminance vector arrived at the retina;This article engaged in a study of the irradiation direction of the light source and the direction of the visual axis under two cases: the light source to regular reflection surface and irregular reflection surface, and tried to inquiry in what proportion of lighting flu...

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