Stoplight Research Articles

Tunable slow light in graphene-based hyperbolic metamaterial waveguide operating in SCLU telecom bands.

The tunability of slow light in graphene-based hyperbolic metamaterial waveguide operating in SCLU telecom bands is investigated. For the first time it has been shown that proper design of a GHMM structure forming waveguide layer and the geometry of the waveguide itself allows stopped light to be obtained in an almost freely selected range of wavelengths within SCLU bands. In particular, the possibility of controlling light propagation in GHMM waveguides by external biasing has been presented. The change of external electric field enables the stop light of the selected wavelength as well as the control of a number of modes, which can be stopped, cut off or supported. Proposed GHMM waveguides could offer great opportunities in the field of integrated photonics that are compatible with CMOS technology, especially since such structures can be utilized as photonic memory cells, tunable optical buffers, delays, optical modulators etc.

Automated Intersection Mapping From Crowd Trajectory Data

Driver assistance systems and automated driving are known to strongly benefit from digital maps. Keeping map attributes up to date is a challenge, particularly for the current manual measuring approach. In this paper, we present methods to extract information about intersections and traffic lights through a crowdsourcing approach. We use position and dynamic data from a fleet of test vehicles with close-to-market sensors. A statistical hypothesis test is proposed to identify groups of driving directions at an entry of an intersection, which have synchronous traffic light signaling. This information is used to improve the detection of the relevant traffic light signal in case there is a different signaling for the driving directions. Based on a test data set, we classified whether the signaling is synchronous or not with an accuracy of 93.8%. To assess the usefulness of our mapping scheme, we have investigated its contribution to a camera-based traffic light recognition system. An evaluation of the use of additional map information for the traffic light detection was performed on a set of 344 logged intersection crossings from this vehicle. We showed that there is an improvement in the accuracy up to 5.2%, dependent on the test conditions.

Traffic Lights Detection and Recognition Based on Color and Shape with SVM

Traffic signal lights recognition system is an essential part of Advanced Driver Assistance Systems (ADAS). Methods for traffic lights recognition based on single feature and fixed threshold filtering are usually ineffective in complex background and variable lighting environment. To solve this problem, an approach based on features combination of color and shape of traffic lights is proposed, and the method of machine learning is used for recognition of traffic lights. On the basis of extracting the characteristic parameters of the candidate region, the SVM classifier is constructed to classify the traffic signal lights. Experimental results show that this method can realize the accurate location and recognition of traffic lights in complex scenes.

Traffic management: Assessing various countermeasures to improve detection failure of changes in speed limit signals

Under certain circumstances, drivers fail to notice changes in electronic speed limits. A video-based study was performed to reveal which countermeasures would improve drivers' ability to detect changes in electronic speed limits. Countermeasures included leaving electronic signs blank prior to a speed limit change and adding motion signals by means of flashing amber lights or a wave. A video representing a motorway was shown repeatedly to 255 participants. They were instructed to press the space bar when detecting a change. The video was viewed 13 times before the speed limit changed. Results showed that leaving signs blank prior to the change instead of displaying speed limits continuously did not alter change detection, whereas flashers and waves eroded detection of the changed speed limit. This suggests that using flashers and waves to attract attention to electronic signs in fact decreases people's ability to process the information contained in the signs.

Influence of Remotely Operated Stop–Slow Controls on Driver Behavior in Work Zones

Remotely operated devices for traffic control—portable traffic lights and automated flagger assistance devices—are used to improve flagger safety in a one-lane-each-way work zone with lane closure. Previous research has measured the effectiveness of these devices as driver compliance rates and driver understanding of the devices, but the effects of these devices on driver behavior have not yet been examined comprehensively. Therefore, the influence of remotely operated stop–slow traffic control devices on driver behavior was examined. Video-recorded traffic movements from a rural work zone in the Queensland state of Australia provided driver speeds, deceleration profiles, stopping behavior, and compliance rates for a set of remotely operated devices new to Australia: static red–amber–green lights, static red–amber lights, static red–amber arrow lights, and mechanical stop–slow signs. Pneumatic tube traffic counters were used to collect driver speeds before and after the devices, and an on-road driver survey was conducted to elicit driver understanding of the devices. Results indicated that drivers had difficulty understanding the new devices, particularly the amber light and amber arrow options (which confused drivers about their meaning—to stop or to go). The new remotely operated devices resulted in higher approach speeds, greater variability in approach speeds, and faster deceleration rates than the flagger method. The good compliance rates observed with the remotely operated devices imply that the devices could improve flagger safety by reducing flagger exposure to traffic; however, the negative effects on driver behavior might indicate an increased risk of rear-end crashes in the advance warning area.

Green wave-based virtual traffic light management scheme with VANETs

Green intelligent transportation systems GITS have received significant attention in recent years. Traffic congestion, which is an important research topic on intelligent transportation systems ITS, is rapidly becoming one of the most serious problems affecting urban areas. This study utilises the vehicular ad hoc networks VANETs technology to build a virtual traffic light VTL environment to reduce traffic congestion. The objective of this study is to adjust the traffic light signal time length on-demand to enable vehicles to pass through numerous intersections rapidly, thereby saving energy and reducing fuel consumption. The traffic phase combination algorithm and VTL operation mechanism are also addressed to improve the traffic congestion situation in urban areas. Simulation results indicate that the proposed scheme can increase the percentage of traffic flow and the average speed of all vehicles in all intersections, thereby saving energy.

Traffic Light Signal Timing Using Simulation

Increasing trend in the number of vehicles and consequently intensifying the traffic volume, traffic lights optimum timing plays a vital role in congestion mitigation in the critical intersections of urban areas. This paper gives an insight into traffic light timing using simulation modeling methods. In fact, this study aims at minimizing the average time that entities (vehicles) spend in the system (intersection). First, real data including vehicles arrive and leave times, and the time spent waiting at a red light etc. is collected through monitoring an intersection in downtown Urmia, Iran. Then, a simulation model is developed using Arena Simulation Software. The most important feature of the proposed model is the replacement a four-stroke traffic light with the current three-stroke one. After model validation, several alternatives are considered for traffic light timing and the one which resulted the minimum average time spent in the system is selected. According to the simulation results, the four-stroke traffic light yielded a better performance compared to the three-stroke one.

Slowing down light using a dendritic cell cluster metasurface waveguide.

Slowing down or even stopping light is the first task to realising optical information transmission and storage. Theoretical studies have revealed that metamaterials can slow down or even stop light; however, the difficulty of preparing metamaterials that operate in visible light hinders progress in the research of slowing or stopping light. Metasurfaces provide a new opportunity to make progress in such research. In this paper, we propose a dendritic cell cluster metasurface consisting of dendritic structures. The simulation results show that dendritic structure can realise abnormal reflection and refraction effects. Single- and double-layer dendritic metasurfaces that respond in visible light were prepared by electrochemical deposition. Abnormal Goos-Hänchen (GH) shifts were experimentally obtained. The rainbow trapping effect was observed in a waveguide constructed using the dendritic metasurface sample. The incident white light was separated into seven colours ranging from blue to red light. The measured transmission energy in the waveguide showed that the energy escaping from the waveguide was zero at the resonant frequency of the sample under a certain amount of incident light. The proposed metasurface has a simple preparation process, functions in visible light, and can be readily extended to the infrared band and communication wavelengths.

Weight management for adolescents with intellectual and developmental disabilities: Rationale and design for an 18 month randomized trial

Adolescents with intellectual and developmental disabilities (IDD) are an underserved group in need of weight management. However, information regarding effective weight management for this group is limited, and is based primarily on results from small, non-powered, non-randomized trials that were not conducted in accordance with current weight management guidelines. Additionally, the comparative effectiveness of emerging dietary approaches, such as portion-controlled meals (PCMs) or program delivery strategies such as video chat using tablet computers have not been evaluated. Therefore, we will conduct an 18month trial to compare weight loss (6months) and maintenance (7–18months) in 123 overweight/obese adolescents with mild to moderate IDD, and a parent, randomized to a weight management intervention delivered remotely using FaceTime™ on an iPad using either a conventional meal plan diet (RD/CD) or a Stop Light diet enhanced with PCMs (RD/eSLD), or conventional diet delivered during face-to-face home visits (FTF/CD). This design will provide an adequately powered comparison of both diet (CD vs. eSLD) and delivery strategy (FTF vs. RD). Exploratory analyses will examine the influence of behavioral session attendance, compliance with recommendations for diet (energy intake), physical activity (min/day), self-monitoring of diet and physical activity, medications, and parental variables including diet quality, physical activity, baseline weight, weight change, and beliefs and attitudes regarding diet and physical activity on both weight loss and maintenance. We will also complete a cost and contingent valuation analysis to compare costs between RD and FTF delivery.

Short Blue Light Pulses (30 Min) in the Morning Support a Sleep-Advancing Protocol in a Home Setting.

Many people in our modern civilized society sleep later on free days compared to work days. This discrepancy in sleep timing will lead to so-called 'social jetlag' on work days with negative consequences for performance and health. Light therapy in the morning is often proposed as the most effective method to advance the circadian rhythm and sleep phase. However, most studies focus on direct effects on the circadian system and not on posttreatment effects on sleep phase and sleep integrity. In this placebo-controlled home study we investigated if blue light, rather than amber light therapy, can phase shift the sleep phase along with the circadian rhythm with preservation of sleep integrity and performance. We selected 42 participants who suffered from 'social jetlag' on workdays. Participants were randomly assigned to either high-intensity blue light exposure or amber light exposure (placebo) with similar photopic illuminance. The protocol consisted of 14 baseline days without sleep restrictions, 9 treatment days with either 30-min blue light pulses or 30-min amber light pulses in the morning along with a sleep advancing scheme and 7 posttreatment days without sleep restrictions. Melatonin samples were taken at days 1, 7, 14 (baseline), day 23 (effect treatment), and day 30 (posttreatment). Light exposure was recorded continuously. Sleep was monitored through actigraphy. Performance was measured with a reaction time task. As expected, the phase advance of the melatonin rhythm from day 14 to day 23 was significantly larger in the blue light exposure group, compared to the amber light group (84 min ± 51 (SD) and 48 min ± 47 (SD) respectively; t36 = 2.23, p < 0.05). Wake-up time during the posttreatment days was slightly earlier compared to baseline in the blue light group compared to slightly later in the amber light group (-21 min ± 33 (SD) and +12 min ± 33 (SD) respectively; F1,35 = 9.20, p < 0.01). The number of sleep bouts was significantly higher in the amber light group compared to the blue light group during sleep in the treatment period (F1,32 = 4.40, p < 0.05). Performance was significantly worse compared to baseline at all times during (F1,13 = 10.1, p < 0.01) and after amber light treatment (F1,13 = 17.1, p < 0.01), while only in the morning during posttreatment in the blue light condition (F1,10 = 9.8, p < 0.05). The data support the conclusion that blue light was able to compensate for the sleep integrity reduction and to a large extent for the performance decrement that was observed in the amber light condition, both probably as a consequence of the advancing sleep schedule. This study shows that blue light therapy in the morning, applied in a home setting, supports a sleep advancing protocol by phase advancing the circadian rhythm as well as sleep timing.

Does the built environment moderate the relationship between having a disability and lower levels of physical activity? A systematic review

The relationship between the built environment and physical activity has been well documented. However, little is known about how the built environment affects physical activity among people with disabilities, who have disproportionately higher rates of physical inactivity and obesity. This study is the first systematic review to examine the role of the built environment as a moderator of the relationship between having a disability (physical, sensory or cognitive) and lower levels of physical activity. After conducting an extensive search of the literature published between 1990 and 2015, 2039 articles were screened, 126 were evaluated by abstract and 66 by full text for eligibility in the review. Data were abstracted using a predefined coding guide and synthesized from both qualitative and quantitative studies to examine evidence of moderation. Nine quantitative and six qualitative articles met the inclusion criteria. Results showed that most research to date has been on older adults with physical disabilities. People with disabilities described how aspects of the built environment affect neighborhood walking, suggesting a positive moderating role of features related to safety and aesthetic qualities, such as benches, lighting and stop light timing. There were mixed results among studies that examined the relationship quantitatively. Most of the studies were not designed to appropriately examine moderation. Future research should utilize valid and reliable built environment measures that are more specific to disability and should include people with and without disabilities to allow for testing of moderation of the built environment.

Amber Light (590 nm) Induces the Breakdown of Lipid Droplets through Autophagy-Related Lysosomal Degradation in Differentiated Adipocytes.

Lipolysis in the adipocytes provides free fatty acids for other tissues in response to the energy demand. With the rapid increase in obesity-related diseases, finding novel stimuli or mechanisms that regulate lipid metabolism becomes important. We examined the effects of visible light (410, 457, 505, 530, 590, and 660 nm) irradiation on lipolysis regulation in adipocytes differentiated from human adipose-derived stem cells (ADSCs). Interestingly, 590 nm (amber) light irradiation significantly reduced the concentration of lipid droplets (LDs). We further investigated the lipolytic signaling pathways that are involved in 590 nm light irradiation-induced breakdown of LDs. Immunoblot analysis revealed that 590 nm light irradiation-induced phosphorylation of hormone-sensitive lipase (HSL) was insufficient to promote reduction of LDs. We observed that 590 nm light irradiation decreased the expression of perilipin 1. We found that 590 nm light irradiation, but not 505 nm, induced conversion of LC3 I to LC3 II, a representative autophagic marker. We further demonstrated that the lysosomal inhibitors leupeptin/NH4Cl inhibited 590 nm light irradiation-induced reduction of LDs in differentiated adipocytes. Our data suggest that 590 nm light irradiation-induced LD breakdown is partially mediated by autophagy-related lysosomal degradation, and can be applied in clinical settings to reduce obesity.

Migraine photophobia originating in cone-driven retinal pathways

Migraine headache is uniquely exacerbated by light. Using psychophysical assessments in patients with normal eyesight we found that green light exacerbates migraine headache significantly less than white, blue, amber or red lights. To delineate mechanisms, we used electroretinography and visual evoked potential recording in patients, and multi-unit recording of dura- and light-sensitive thalamic neurons in rats to show that green activates cone-driven retinal pathways to a lesser extent than white, blue and red; that thalamic neurons are most responsive to blue and least responsive to green; and that cortical responses to green are significantly smaller than those generated by blue, amber and red lights. These findings suggest that patients' experience with colour and migraine photophobia could originate in cone-driven retinal pathways, fine-tuned in relay thalamic neurons outside the main visual pathway, and preserved by the cortex. Additionally, the findings provide substrate for the soothing effects of green light.

An LED-Based Fluorescent Sensing System for on-Site Microalgal Detection

In this work, we present a fluorescent sensing system capable of simultaneously detecting two species during microalgal co-culture, in which microalgae (C. vulgaris) and cyanobacteria (Leptolyngbya sp.) are the target species for detection. The sensing system has two different excitation light sources for stimulating chlorophyll ain microalgae and phycocyanin pigment in cyanobacteria, respectively, and a photodetector to measure corresponding fluorescent signals. This work is a significant improvement over our previous report on a fluorescent sensing system for single species [1]. Microalgae are one of the promising alternative energy sources [2]. Recent reports show that a co-culture system enhances biofuel production [3] and it is desired to monitor the population of each species. The co-inoculation of microalgae and cyanobacteria promotes the growth rate and lifespan of microalgae [4,5]. It is highly desired to simultaneously monitor the populations of microalgae and cyanobacteria in order to obtain highly efficient biofuel production. A common method is bench-top flow cytometry, which is time consuming, expensive, and difficult to deploy for on-site detection. The proposed portable fluorescent sensing system can be a viable option for on-site monitoring of co-culture solution containing microalgae and cyanobacteria. For the fluorescent sensing system, blue LEDs (448 nm peak wavelength) were selected for stimulating microalgae and amber LEDs (590 nm) for cyanobacteria. A highly sensitive silicon photomuliplier, MicroFC (SensL Inc., Cork, Ireland), was implemented to detect a low fluorescent signal from phycocyanin in cyanobacteria. Chlorophyll aand phycocyanin emit fluorescent light with the peak wavelength around 680 nm and 645 nm, respectively. Two long-pass filters, a dichroic filter with 647 nm cut-off (PIXELTEQ, Largo, FL, USA) and a color filter with 645 nm cut-off (Edmund Optics, Barrington, NJ, USA), are placed in front of the silicon photomultiplier to block the excitation light as illustrated in Figure 1. Measured results show that the photocurrent increases with the population of microalgae under the blue excitation light while its change is not significant to the amber light. Likewise, the photocurrent increases with the concentration of phycocyanin pigments under the amber excitation light while its response to the blue light is minimal. In summary, we have developed and demonstrated a portable fluorescent sensing system that is capable of differentiating microalgae and cyanobacteria. With further optimization, the developed system can be deployed in a biofuel production system for continuous monitoring of co-culture solution. Future work will also include integrated electronic circuitry for a fully standalone fluorescent detection system.

Highly improved reliability of amber light emitting diode with Ca -α-SiAlON phosphor in glass formed by gas pressure sintering for automotive applications.

Phosphor in glass (PiG) with 40 wt% of Ca-α-SiAlON phosphor and 60 wt% of Pb-free silicate glass was synthesized and mounted on a high-power blue LED to make an amber LED for automotive applications. Gas pressure sintering was applied after the conventional sintering process was used to achieve fully dense PiG plates. Changes in photoluminescence spectra and color coordination were inspected by varying the thickness of the plates that were mounted after optical polishing and machining. A trade-off between luminous flux and color purity was observed. The commercial feasibility of amber PiG packaged LED, which can satisfy international regulations for automotive components, was successfully demonstrated by examining the practical reliability under 85% humidity at an 85°C condition.

КООРДИНИРОВАННОЕ СВЕТОФОРНОЕ УПРАВЛЕНИЕ АВТОТРАНСПОРТНЫМИ ПОТОКАМИ НА МАГИСТРАЛИ Г. ЛИПЕЦКА

The article investigates traffic flow of lipetsk of Vodopyanov street. Based on the research proposes a change of operation modes of a traffic light signaling, which allow to reduce the likelihood of congestion and the amount of harmful substances in the environment.

시뮬레이션 기법을 통한 효율적 스마트 보행신호등 메커니즘 구축

The walking speed of handicapped people generally is slower than that of normal people. So it is difficult for them to cross at crosswalks within the allotted time provided by the traffic light. This problem can be solved by expanding the time of the traffic light. However, if the latency of the traffic light is increased without distinguishing the handicapped among all other pedestrians, the efficiency of traffic signal lights will decrease. In this paper, we propose a smart traffic signal connecting mechanism between the previous pedestrian traffic signal and a pedestrian's device (smartphone). This Smart pedestrian traffic light, through this mechanism, minimizes traffic congestion by providing additional walking time only to the handicapped among pedestrians. This crosswalk traffic light recognizes the handicapped using a technique called Internet of things (IOT). In this paper, we extract the data necessary to build an effective smart crosswalk traffic light mechanism through simulation techniques. We have extracted different kinds of traffic signal times with our virtual simulation environment to verify the efficiency of the smart crosswalk pedestrian traffic light system. This approach can validate the effective delay time of the traffic signal time through a comparison based on number of pedestrians.

Exposure to blue wavelength light modulates anterior cingulate cortex activation in response to ‘uncertain’ versus ‘certain’ anticipation of positive stimuli

Blue wavelength light has been used as an effective treatment for some types of mood disorders and circadian rhythm related sleep problems. We hypothesized that acute exposure to blue wavelength light would directly affect the functioning of neurocircuity implicated in emotion regulation (i.e., ventromedial prefrontal cortex, amygdala, insula, and anterior cingulate cortex [ACC]) during ‘certain’ and ‘uncertain’ anticipation of negative and positive stimuli. Thirty-five healthy adults were randomized to receive a thirty-minute exposure to either blue (active) or amber (placebo) light, immediately followed by an emotional anticipation task during functional magnetic resonance imaging (fMRI). In contrast to placebo, participants in the blue light group showed significantly reduced activation within the rostral ACC during ‘uncertain’ anticipation (i.e., uncertainty regarding whether a positive or negative stimulus would be shown) in comparison to ‘certain’ anticipation of a positive stimulus. These findings may be explicable in terms of interactions between blue light exposure and the influence of specific neuromodulators on ACC-mediated decision-making mechanisms.

An assessment of ‘turtle-friendly' lights on the sea-finding behaviour of loggerhead turtle hatchlings (Caretta caretta)

Context It is well established that artificial light can disrupt the sea-finding ability of sea turtle hatchlings, and some manufactures are now marketing ‘turtle-friendly’ lights that are supposed to be minimally disruptive to this sea-finding behaviour. However, there have been no studies that have tested whether ‘turtle-friendly’ lights are benign to hatchling sea turtle sea-finding ability. Aims We tested two different types of ‘turtle-friendly’ lights (LED amber-light peak intensity 620 nm and LED red-light peak intensity 640 nm) to see whether they are disruptive to the sea-finding ability of eastern-coast Australian loggerhead turtle hatchlings. Methods Using standard circular-arena experiments, we assessed the directional preference of newly emerged loggerhead turtle hatchlings from the Woongarra Coast of Queensland, Australia, during different moon phases without artificial lighting and in the presence of ‘turtle-friendly’ lights. Key results Contrary to expectations, sea-finding ability of hatchlings was disrupted by the amber lights, particularly in the absence of a moon. The less intense red lights were less disruptive to hatchlings; however, misorientation and disorientation events still occurred when lights were within 4 m of hatchlings. The disruptive impact on sea-finding ability increased with the cumulative impact of multiple lights increasing light intensity. Conclusions The ‘turtle-friendly’ lights we used disrupted the sea-finding ability of eastern-coast Australian loggerhead turtle hatchlings, with the most pronounced disruption occurring under moonless conditions. Implications The use of amber and red LED lights adjacent to the nesting beaches of loggerhead sea turtles should be managed because this lighting has the potential to disrupt the sea-finding ability of sea turtle hatchlings.

A Traffic Light Signal Control System with Truck Priority1*This work has been supported in part by the National Science Foundation under the CPS program and in part by the University Transportation Center METRANS at University of Southern California.

Abstract: This paper proposed and evaluated a traffic light control system for signalized urban intersections that aims to benefit all traffic flows involved by giving priority to trucks. The problem is motivated from the observation that in some cases extending a green traffic signal to have a heavy truck cross an intersection instead of forcing it to stop and restart again may have benefits for all vehicles involved. The proposed traffic light control system uses a co-simulation optimization control approach to generate the traffic light sequence in a network of signalized intersections. The system has been evaluated using a road network simulator adjacent to the twin ports of Long Beach/Los Angeles. The evaluation results show consistent improvements in reducing the overall traffic delays, number of vehicle stops, fuel consumption and vehicle emissions.