Leukos最新文献_第9页

Study of Heart Rate and Blood Pressure Subject to Pulsed LED Lighting 脉冲LED照明下心率和血压的研究

IF 3.6 2区工程技术

Leukos Pub Date : 2021-06-30 DOI: 10.1080/15502724.2021.1920974

Luyao Tang, Xiaolin Zhang, Xiaoli Zhou, Xinyuan Gu, Shenglong Fan, Muqing Liu

{"title":"Study of Heart Rate and Blood Pressure Subject to Pulsed LED Lighting","authors":"Luyao Tang, Xiaolin Zhang, Xiaoli Zhou, Xinyuan Gu, Shenglong Fan, Muqing Liu","doi":"10.1080/15502724.2021.1920974","DOIUrl":"https://doi.org/10.1080/15502724.2021.1920974","url":null,"abstract":"ABSTRACT It has been proved that lighting has nonvisual effects on the human body, including changes in heart rate and blood pressure. Heart rate and blood pressure are associated with the autonomic nervous system and can indicate stress level. The present study investigates whether heart rate and blood pressure are influenced by the frequency or duty cycle of pulsed light, together with the duration of lighting. Twelve healthy young subjects were recruited for the investigation. Subjects were exposed to pulsed light of varying frequencies (40 Hz, 100 Hz, 300 Hz) and duty cycles (10%, 50%, 90%). Exposure time was divided into two groups: short-time (20 min) and long-time (3 hours). Heart rate and blood pressure were measured during the experiments. Results showed that after a short lighting period (20 min), heart rate and blood pressure were significantly higher under 40 Hz pulsed than that under stable light, while 100 Hz and 300 Hz had no significant difference. After 3 hours of exposure time, the two indices became higher under 100 Hz (no flicker perceived with eyes) with 10% duty cycle, while 50% and 90% duty cycle showed no significant difference. These findings indicate that pulsed light will cause a deviation of heart rate and blood pressure from that under stable light.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89987504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the Relation between the Astronomical and Visual Photometric Systems in Specifying the Brightness of the Night Sky for Mesopically Adapted Observers 天文测光系统与视觉测光系统在中观观测者确定夜空亮度中的关系

IF 3.6 2区工程技术

Leukos Pub Date : 2021-06-25 DOI: 10.1080/15502724.2021.1921593

I. Fryc, S. Bará, M. Aubé, J. Barentine, J. Zamorano

{"title":"On the Relation between the Astronomical and Visual Photometric Systems in Specifying the Brightness of the Night Sky for Mesopically Adapted Observers","authors":"I. Fryc, S. Bará, M. Aubé, J. Barentine, J. Zamorano","doi":"10.1080/15502724.2021.1921593","DOIUrl":"https://doi.org/10.1080/15502724.2021.1921593","url":null,"abstract":"ABSTRACT Due to the typical ambient light levels in inhabited places and light pollution of the night sky, most naked-eye astronomical observations are performed nowadays under mesopic conditions. The luminance (cd/m2) associated with the brightness of the night sky specified in the astronomical logarithmic scale of magnitudes per square arcsecond (mag/arcsec2) is strongly dependent on the spectrum of the sky, because the spectral sensitivity of the human visual system is not coincident with the standard photometric bands used in astronomy. The conversion between these two families of photometric systems was previously analyzed for observers presumed to be either fully photopically or scotopically adapted. In this work, we deduce the transformation equations between the astronomical and visual photometric systems for specifying and reporting the sky brightness in the mesopic range, within the framework of the MES-2 system for visual performance-based mesopic photometry. It is shown that the dependence of the conversion factors on the correlated color temperature of the night sky reaches a minimum spread for adaptation luminances of 0.5–1.0 cd/m2. The sky luminances corresponding to 22.0 mag/arcsec2 in the Johnson-Cousins V band (the assumed brightness of a natural night sky devoid of light pollution) span, for 1.0 cd/m2 adaptation, a relatively small range of ~195–215 μcd/m2 in the absolute (AB) magnitude system and ~210–225 μcd/m2 in the Vega-referenced one.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84631573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

An Approach for Determining an Index for Lightness-Darkness Attribute of Shadows in Artificial Lit Spaces 人工照明空间中阴影明暗属性指数的确定方法

IF 3.6 2区工程技术

Leukos Pub Date : 2021-05-19 DOI: 10.1080/15502724.2021.1896366

Selcen Akbay Çelikmez, L. Öztürk

{"title":"An Approach for Determining an Index for Lightness-Darkness Attribute of Shadows in Artificial Lit Spaces","authors":"Selcen Akbay Çelikmez, L. Öztürk","doi":"10.1080/15502724.2021.1896366","DOIUrl":"https://doi.org/10.1080/15502724.2021.1896366","url":null,"abstract":"ABSTRACT Shadows, modelling, and directional lighting are lighting criteria which are closely related with each other. Shadows have two attributes, namely harshness-softness and lightness-darkness. Both attributes can be examined in two respects that is self-shadow and cast-shadow. A shadow with sharp edges is harsh shadow, while a shadow with blurred edges is soft shadow. The size of the luminaire determines whether the edges of a shadow are sharp or blur. The contrast between the illuminated and the shaded areas determines the lightness-darkness of shadows. If this contrast is weak the shadow is perceived as light, while a strong contrast causes the shadow to be perceived as dark. The observer is often unable to distinguish the effects of two different shadow attributes from each other and judges the appearance of objects or faces as a whole as pleasant or not. However, the two properties of shadows can be defined independently from each other and considered separately as lighting design criteria. Directional lighting is used when the texture and shape of objects or people are to be revealed or emphasized. Finally, it can be said that modelling describes the general appearance of objects and people and involves both the shadow properties and the effects of directional lighting. The aim of this study is to define an index with regard to the lightness-darkness attribute of shadows. The approach developed in this respect is applied for both cast- and self-shadows. The acceptable limits for both indexes are determined based on the main types of luminaires that are often installed in a room. The introduced lightness-darkness indexes with their limit values can be considered as lighting design criteria.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2021-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81292745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Visualization of Lighting Quality and Object Appearance When Using Multichannel Light Sources 使用多通道光源时照明质量和对象外观的可视化

IF 3.6 2区工程技术

Leukos Pub Date : 2021-04-08 DOI: 10.1080/15502724.2021.1887744

Kaveh Ahmadian Tazehmahaleh, Kevin A. G. Smet, P. Hanselaer

{"title":"Visualization of Lighting Quality and Object Appearance When Using Multichannel Light Sources","authors":"Kaveh Ahmadian Tazehmahaleh, Kevin A. G. Smet, P. Hanselaer","doi":"10.1080/15502724.2021.1887744","DOIUrl":"https://doi.org/10.1080/15502724.2021.1887744","url":null,"abstract":"ABSTRACT The availability of quasi-monochromatic Light Emitting Diodes (LEDs) with peak wavelengths distributed over the visible spectrum has opened the way to the development of multichannel LED light sources generating tunable illumination spectra. As the color appearance of an object is strongly influenced by the spectral power distribution of the light source, these multichannel light sources are also commonly used as a research tool in color quality studies. In a number of studies, spectrum optimization algorithms are applied in order to generate a target spectrum directly. Other papers report on the calculation of an illumination spectrum with the aim to optimize one or a set of general quality metrics such as the luminous efficacy of radiation and the color rendering index Ra or Rf. The approach followed in this paper is to explore and visualize, for a given multichannel LED light source, the lighting quality parameters which can be reached within the chromaticity gamut for a selected object. For any predefined target white point chromaticity, the illumination metamers are calculated analytically within the constraints defined by the multichannel LED light source under consideration. The solution space is sampled with a brute force method and the values of any general or specific color quality index can be evaluated. For a predefined object spectral reflectance (or one typical spectral reflectance representative for a set of objects), the object chromaticity gamut is derived. Several object chromaticity targets within the gamut, such as the memory color of familiar objects, can be selected and the impact of “local” variations of the hue and chroma within this gamut on the general and special lighting quality indices and on the user preference can be checked. This can simplify the selection of an object-based optimum illumination spectrum. The approach is illustrated in practice using a five-channel LED light source which was developed in-house.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2021-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77321205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

It’s Official, Light is Not Just for Vision 光不仅仅是为了视觉

IF 3.6 2区工程技术

Leukos Pub Date : 2021-04-03 DOI: 10.1080/15502724.2021.1885271

K. Houser

引用次数: 1

A Review of Human Physiological Responses to Light: Implications for the Development of Integrative Lighting Solutions 人类对光的生理反应综述:对综合照明解决方案发展的启示

IF 3.6 2区工程技术

Leukos Pub Date : 2021-03-26 DOI: 10.1080/15502724.2021.1872383

C. Vetter, P. Pattison, K. Houser, M. Herf, A. Phillips, K. Wright, D. Skene, G. Brainard, D. Boivin, G. Glickman

{"title":"A Review of Human Physiological Responses to Light: Implications for the Development of Integrative Lighting Solutions","authors":"C. Vetter, P. Pattison, K. Houser, M. Herf, A. Phillips, K. Wright, D. Skene, G. Brainard, D. Boivin, G. Glickman","doi":"10.1080/15502724.2021.1872383","DOIUrl":"https://doi.org/10.1080/15502724.2021.1872383","url":null,"abstract":"ABSTRACT Architectural lighting has potent biological effects but applied lighting practices that capitalize on this potential have been limited. In this review, we endeavor to consolidate and synthesize key references that will be useful for lighting professionals, with the goal of supporting knowledge translation into pragmatic lighting strategies. Specifically, we explain relevant terminology, outline basic concepts, identify key references, provide a balanced overview of the current state of knowledge, and highlight important remaining questions. We summarize the physiological effects of light on human health and well-being, including a description of the processes underlying the photic regulation of circadian, neuroendocrine, and neurobehavioral functions. We review seminal work elucidating the elements mediating the potency of light for these physiological responses, with specific attention to factors critical for interpreting those findings. In parallel, we explain and endorse melanopic Equivalent Daylight Illuminance ( ) as the preferred measure to quantify the biological potency of light. Ultimately, while future studies are necessary to further facilitate the translation of laboratory knowledge to domestic and workplace settings, the immediate potential for applied lighting to better support human health is clear. Aiming for integrative lighting solutions that have biologically high potency light during the day and low potency during the night is perhaps the most immediate improvement to be made in order to better support applications for humans.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2021-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76967698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 72

Tutorial: Background and Guidance for Using the ANSI/IES TM-30 Method for Evaluating Light Source Color Rendition 教程:使用ANSI/IES TM-30方法评估光源颜色还原的背景和指南

IF 3.6 2区工程技术

Leukos Pub Date : 2021-03-16 DOI: 10.1080/15502724.2020.1860771

Michael P. Royer

引用次数: 13

Prime Color Wavelengths Improve Color Discrimination 原色波长改善颜色辨别

IF 3.6 2区工程技术

Leukos Pub Date : 2021-03-01 DOI: 10.1080/15502724.2020.1871361

T. Esposito

引用次数: 1

Impact of Color Matching Primaries on Observer Matching: Part II – Observer Variability 原色匹配对观察者匹配的影响:第二部分——观察者的可变性

IF 3.6 2区工程技术

Leukos Pub Date : 2021-02-25 DOI: 10.1080/15502724.2020.1864396

Jiaye Li, P. Hanselaer, Kevin A. G. Smet

{"title":"Impact of Color Matching Primaries on Observer Matching: Part II – Observer Variability","authors":"Jiaye Li, P. Hanselaer, Kevin A. G. Smet","doi":"10.1080/15502724.2020.1864396","DOIUrl":"https://doi.org/10.1080/15502724.2020.1864396","url":null,"abstract":"ABSTRACT In this study, the observer variability in a 10° achromatic color matching experiment using systematically different primaries under immersive, perceptually neutral (4673 K) and stable adapted viewing conditions have been investigated for four different sets of CIE color matching functions (CMFs). The matching reference was illuminated by a spectrally broadband light source at 70 cd/m2 and 4613 K. Fifty-four observers varying in age, gender, ethnicity and eye color participated. The results indicate that certain wavelength regions are more sensitive to generate interobserver variability, such as when a short wavelength primary (404 nm) was applied. Furthermore, of the primary sets investigated, that with peak-wavelengths (636–521–447 nm) close to the “typical” RGB-primaries widely known and used in industry had the smallest interobserver variability. In addition to the significant effect of primary set and CMF set, a significant effect of age on matching variability is also found, whereby the change of the blue primary resulted in a substantial difference in dispersion between younger and older observers, likely caused by age-induced yellowing of the lens. Furthermore, different primary sets tend to have a different impact on intra-observer variability than on interobserver variability. Finally, by comparing the observer variability in the current work with previous studies, the CIE standard deviate observer is found to substantially underestimate the interobserver variability, especially for the primary sets containing a 404 nm LED. Our observers also tend to have similar to smaller inter-variability than those reported in literature, possibly due to methodological differences.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2021-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15502724.2020.1864396","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72400718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Regional Differences in the Perception of Daylit Scenes across Europe Using Virtual Reality. Part I: Effects of Window Size 使用虚拟现实技术感知欧洲白天场景的地区差异。第一部分:窗口大小的影响

IF 3.6 2区工程技术

Leukos Pub Date : 2021-02-18 DOI: 10.1080/15502724.2020.1854779

C. Moscoso, K. Chamilothori, J. Wienold, M. Andersen, B. Matusiak

{"title":"Regional Differences in the Perception of Daylit Scenes across Europe Using Virtual Reality. Part I: Effects of Window Size","authors":"C. Moscoso, K. Chamilothori, J. Wienold, M. Andersen, B. Matusiak","doi":"10.1080/15502724.2020.1854779","DOIUrl":"https://doi.org/10.1080/15502724.2020.1854779","url":null,"abstract":"ABSTRACT The size of window openings is widely acknowledged as an important factor in our spatial perception. However, little is known about how the perception and preference of windows changes between countries, leaving a gap of knowledge regarding the applicability of research findings across latitudes. This article presents the outcomes of a study investigating regional differences in the perception of spaces with varying window size (small, medium, and large), space size (small and large), spatial context (working and social), and sky type (overcast and two types of clear sky). As the regional differences were the main studied factor, the study was performed in Norway, Switzerland, and Greece, representing northern, central, and southern European latitudes, respectively, and used virtual reality as a means to replicate the same experiment in different locations. In total, 406 participants evaluated eight spatial attributes using an 11-point Likert-type scale. Results indicated that regional differences could be observed in the participants’ responses, with significant differences in how pleasant and calm the space was perceived, found not only between participants in Greece and Norway in all the studied window sizes, but also between Greece and Switzerland for the medium and large windows, indicating that even small variations in latitude within Europe can affect the spatial perception. The findings of this study reveal that spaces with specific fenestration characteristics might not induce the same response across different latitudes in Europe, and thus, have important implications for daylighting and architectural design, which would motivate the use of region-specific parameters.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89754808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15