Pedestrian visibility at night: The effect of solid state streetlights

2016 ◽  
Vol 48 (8) ◽  
pp. 976-991 ◽  
Author(s):  
R Saraiji ◽  
D Younis ◽  
MT Madi ◽  
RB Gibbons

This study examines the effect of different types of lamps on pedestrian night time visibility. Detection distance was used as a measure of visibility. The detection distance was measured in the presence and in the absence of on-coming car headlamps in an unlit street. Subsequently, the street was lit using metal halide, high-pressure sodium or LED luminaires. A pedestrian who changed his clothing colour randomly was used as a target. The results showed that the detection distance on the unlit road was 52% shorter in the presence of on coming car headlamps than when the oncoming car headlamps were off. A person wearing black clothing was harder to see and their mean detection distance was 60% less than when the observer was not dazzled by the oncoming car headlights. When the street was lit, the detection distance was doubled. The mean detection distance using LED lamps was statistically similar to that obtained using metal halide lamps, both of which were better than the detection distance obtained under high pressure sodium lighting.

2012 ◽  
Vol 229-231 ◽  
pp. 2610-2614
Author(s):  
Min Li ◽  
Qiu Yi Han ◽  
Wei Li ◽  
Shui Jun Shi ◽  
Hao Jun Zhang ◽  
...  

As a rapid developing solid state lighting, light-emitting diodes (LEDs) have great potential in application of road lighting, but their performance evaluation in a long term are still lacked. In situ and laboratory measurements were conducted for the purpose of comparing the characteristic parameters and lighting performance of three kinds of street lamps: LEDs, high pressure sodium (HPS) lamps and ceramic discharge metal halide (CDM) lamps. The results of laboratory measurements in 2000 hours show the three kinds of lamps have almost the same initial luminaire efficacy, which lead to the average road illuminance is proportion to the lamp power. The results of road illuminance distribution measurements in 3000 hours show LEDs have better color rendering index, longitudinal uniformity of illuminance, and maintenance of road illuminance than HPS and CDM lamps.


HortScience ◽  
1993 ◽  
Vol 28 (6) ◽  
pp. 621-622 ◽  
Author(s):  
G.L. Roberts ◽  
M.J. Tsujita ◽  
B. Dansereau

Rosa ×hybrida `Samantha' plants were grown under high-pressure sodium (HPS) lamps, HPS lamps fitted with blue gel filters to reduce the red to far-red (R:FR) ratio, or metal halide lamps. R: FR ratios were 1:0.95, 1:2, and 1:0.26 for HPS; filtered HPS, and metal halide, respectively. Although the R: FR ratio for metal halide was 3.5 times higher than for HPS, the total energy from 630 to 750 nm was 2.8 times lower. At a nighttime supplemental photosynthetic photon flux of 70 to 75 μmol·m-2.s-1, plants under HPS and metal halide lamps produced 49 % and 64% more flowering shoots, respectively, than those under filtered HPS (averaged over two crop cycles). The quality index for flowers under HPS, metal halide, and filtered HPS was 25.0, 23.3, and 18.5, respectively. Vase life was 10 to 11 days, regardless of treatment.


Crystals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 394 ◽  
Author(s):  
Fu-Ming Tzu ◽  
Jung-Hua Chou

Light sources tend to affect images captured in any automatic optical inspection (AOI) system. In this study, the effectiveness of metal-halide lamps, quartz-halogen lamps, and LEDs as the light sources in AOI systems for the detection of the third and fourth layers electrodes of thin-film-transistor liquid crystal displays (TFT-LCDs) is examined experimentally. The results show that the performance of LEDs is generally comparable or better than that of metal-halide and quartz-halogen lamps. The best optical performance is by the blue LED due to its spectrum compatibility with the time-delay-integration charged-coupled device (TDI CCD) sensor and its better spatial resolution. The images revealed by the blue LED are sharper and more distinctive. Since current LEDs are more energy efficient and environmentally friendly, using LEDs as the light source for AOI is very beneficial. As the blue LED performs the best, it should be adopted for AOI using TDI CCD sensors.


2021 ◽  
Vol 8 (10) ◽  
pp. 537-541
Author(s):  
Dineshkanth Vudayana ◽  
Lakshmi Sativada ◽  
Pavani Jerry ◽  
Padmaraju Kolluru

BACKGROUND Lens induced glaucomas are common in India. There were different types of lens induced glaucomas based on clinical features and morphological features. This study was undertaken to evaluate the various characteristics and presentations of glaucomas, to define the risk factors and to evaluate as to how they influence the post-operative visual acuity, intra ocular pressure, inflammation and optic disc changes. METHODS This longitudinal study included 90 cases of lens induced glaucoma admitted in the ophthalmic wards of the Great Eastern Medical School and Hospital, Srikakulam, during the period March 2018 to March 2020. All consecutive patients diagnosed as lens induced glaucoma on the basis of clinical symptoms and signs were included. At presentation, visual acuity, IOP, inflammation including corneal changes were recorded, which were repeated after institution of medical line of treatment and postoperatively patients were followed up regularly at 2, 4 and 6 weeks intervals and the same parameters were evaluated including optic disc changes. RESULTS Occurrence of lens induced glaucoma in the hospital during the study period was 1.72 %. The mean age of presentation of various types of glaucomas was 60.57 years and the female to male ratio was 2:1. The most frequent type of lens induced glaucoma was phacomorphic glaucoma (70 %). In 34.4 % patients best corrected visual acuity was found to be better than 6 / 18. In 14.4 % of cases, visual acuity was found be worse than 6 / 60. In patients who presented with symptoms of less than two weeks duration, better visual acuity of 6 / 12 or more was noted (76.2 %, P < 0.01). In 60 % patients who presented with IOP levels of less than 35 mmHg, better visual acuity of 6 / 12 or more was noted in 76.2 %. The mean IOP noted in patients with symptoms of 2 to 4 weeks duration was found to be 40.33 ± 9.36 mmHg. Inflammation was more severe in patients who were symptomatic for more than 2 weeks (37.50 %, P < 0.05) and also in cases with IOP more than 35 mmHg (40 %). Optic disc of the presented eye was found to be damaged in 35.5 % of cases and in patients presenting with symptoms of more than 2 weeks’ duration it was 62.5 % (P < 0.01). CONCLUSIONS Presentation with intraocular pressure value greater than 35 mm of Hg and with symptoms of more than two weeks would result in severe inflammation further affecting the cornea and causing optic nerve damage which would ultimately jeopardize vision. This can be prevented by early presentation and regular screening of people above 60 years of age. KEYWORDS Lens-Induced, Glaucoma, Cataract


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