Visibility Distance Research Articles

Smartphone-deployable and all-in-one machine vision for visual quantification analysis based on distance readout of electrophoresis titration biosensor

As a class of point-of-care (POC) assays with visible distance readout (thermometer style), the electrophoresis titration (ET) biosensor affords high robustness, versatility, and simplicity for point-of-care quantification. However, naked-eye observation of the distance readout is unreliable in POC settings and manual processing of distance readout is time-consuming. Herein, we developed a smartphone-deployable and all-in-one machine vision for four ET biosensors (bovine serum albumin, melamine, uric acid, glutathione) to classify and quantify the samples simultaneously. To ensure accurate and rapid quantification on the smartphone, we customized the decolorization methods and edge detection operators to balance the region of interest (ROI) extraction performance and processing speed. We then established a dataset of 180 distance readout images to endow our machine vision with the ability to classify four sample types. Consequently, our machine vision demonstrated high accuracy in determining the sample type (>97.2%) and concentration (>97.3%). Moreover, expanding its applications to other targets was readily achieved by including distance readout images of other ET biosensors (e.g., hemoglobin A1c) in the dataset. Therefore, our strategy of constructing machine vision is compatible with the versatile ET biosensor technique, suggesting that the same strategy can be used for other thermometer-style POC assays.

Experimental study on effect of pavement background on obstacle visibility in LED lighting environment of road tunnel

The tunnel pavement is generally made of asphalt or concrete. Due to the relatively fixed material of pavement, the effect of tunnel pavement setting on the lighting environment and visual performance of drivers has not received sufficient attention, especially the impact on the visual performance of drivers during driving has not been revealed. Therefore, experimental research on the visual recognition performance of an obstacle on asphalt and concrete pavements inside tunnels during dynamic driving was conducted in this study. The results indicate that under the same pavement illumination, the luminance on concrete pavement is higher than that on asphalt pavement due to the higher reflectance of concrete. The visible distance of the human eyes for a gray obstacle with a reflectance of 0.2 on the concrete pavement is greater than that on the asphalt pavement, and the visible distance of the obstacle on the concrete pavement increases by more than 28%. When the color of the obstacle and the pavement are close, it can be challenging for observers to recognize the obstacle, and the pavement and obstacle need to have a higher level of luminance for the recognition. During dynamic driving, the visible distance at a speed of 60 km/h is 1.2 to 1.4 times that at a speed of 80 km/h, which means the influence of vehicle speed on the human eye’s recognition of obstacles on asphalt and concrete pavements should be taken into consideration in the design of road tunnel lighting. The correlated color temperature and S/P value of LED light have little impact on the visible distance of human eyes to the obstacle on the asphalt and concrete pavements, but it does create different visual perceptions. As the correlated color temperature and S/P value increase, the lighting environment of the tunnel gradually gives a brighter feeling to drivers.

Strange nonchaotic attractors and bifurcation of a four-wheel-steering vehicle system with driver steering control

In this paper, a dynamical model is developed for the four-wheel-steering(4WS)vehicles, with nonlinear lateral tyre forces and quasi-periodic disturbances from the steering mechanism and quasi-periodic pavement external deformation. Initially, the stability and Hopf bifurcation of the 4WS vehicle system without disturbance are analyzed employing the central manifold theory and projection method. The effects of parameters on the stability and the types of Hopf bifurcation for the vehicle system are also discussed. It is shown that both Hopf bifurcation and degenerate Hopf bifurcation occur in the vehicle system. The critical speed decreases with increased driver’s perceptual time delay and distance from the vehicle’s center of gravity to the front axles, while it increases with the control strategy coefficient. However, the increase of the frontal visibility distance of the driver leads to an initial increase of the critical speed, decreasing afterwards. Subsequently, the strange nonchaotic dynamical behaviour of the disturbed 4WS system is investigated. Several routes and mechanisms for the birth of strange nonchaotic attractors (SNAs) are identified, including the torus doubling bifurcation, the torus fractalization, and the loss of transverse stability of a torus. Finally, the nonchaotic property is verified through the calculation of the maximum Lyapunov exponent, and the strange property is characterized using power spectra and rational approximation.

Distance-based paper device coupled with uracil-rich DNA hydrogel for visual quantification of Uracil-DNA glycosylase

Uracil-DNA glycosylase (UDG), an enzyme for repairing uracil-containing DNA damage, is crucial for maintaining genomic stability. Simple and fast quantification of UDG activity is essential for biological assay and clinical diagnosis, since its aberrant level is associated with DNA damage and various diseases. Herein, we developed a fully integrated “sample in-signal out” distance-based paper analytical device (dPAD) for visual quantification of UDG using a flow-controlled uracil-rich DNA hydrogel (URDH). The uracil base sites contained in the DNA hydrogel are mis-incorporated with dUTP by rolling circle amplification (RCA), which simplifies the preparation process of the functionalized hydrogel. In the presence of UDG, the uracil in URDH can be recognized and removed to induce the permeability change of URDH, resulting in the visible distance signal along the paper channel. Using dPAD, as low as 6.4 × 10−4 U/mL of UDG (within 80 min) is visually identified without any instruments and complicated operations. This integrated dPAD is advantageous for its simplicity, cost effectiveness, and ease of use. We envision that it has the great potential for point-of-care testing (POCT) in DNA damage testing, personalized healthcare assessment, and biomedical applications.

Design and Initiation of Lidar Based Visibility Distance Estimation Under Adverse Weather for Collision Avoidance in Fog

The vehicle detection in fog using LIDAR offers a practical solution for staying safe from the road accidents in the foggy condition. The purpose of our endeavor is to develop a vehicle detection system using LIDAR technology to identify and track vehicles within foggy conditions. The system is implemented on Raspberry pi for real-time testing. A camera captures the images and the computer vision is applied to identify whether fog and vehicle is present. If fog and vehicle is presented it send signal for LIDAR to turn on in which sensor fixed on a vehicle to look through the surrounding environment and generate a 3D point cloud depiction of the environment and which give the distance between vehicles. ultrasonic sensor which signals driver to concentrate when vehicle is close to the sides of road divider to avoid hitting them. It gives signal to DC motor which control the movement of the vehicle and motor driver which control the DC motor from giving the reverse current to the PCB of the Raspberry Pi. An electrical source supplies the necessary power for the working of various components. The software tool used is OpenCV with python programming. Finally, when LIDAR and laser module senses the vehicle and detects the separation between them it displays the result on the OLED display screen and indicate through the buzzer.

Spatial-temporal patterns and influencing factors of the Building Green View Index: A new approach for quantifying 3D urban greenery visibility

The vertical expansion of urbanization has increased the morphological heterogeneity of the urban landscape, affecting the physical and emotional wellbeing of urban dwellers by obstructing the view of greenery. In this study, multisource spatial data was used to calculate the Building Green View Index (BGVI). Baidu Street View (BSV) images were collected for comparison with the corresponding BGVI results. A random forest model was used to analyze the contributions and marginal effects of multiple influencing factors on BGVI. The results indicated that approximately 76.10 % of the sampled sites had a higher BGVI than the street view green view index, indicating buildings' superiority of visible greenery in height. The western edge of the research region frequently had the highest BGVI. Meanwhile, the hotspot regions were primarily located in the west, which was more consistent with the distribution of high value zones. The green area within the maximum visible distance, the maximum visible distance, and the average height were the most influential factors of BGVI according to marginal effects analysis with the highest IncNodePurity. As a quantitative measure of urban dwellers’ visual accessibility to green space, the BGVI will contribute to urban green planning and the development of landscape architecture.

The Long Hazy Tail: Analysis of the Impacts and Trends of Severe Outdoor and Indoor Air Pollution in North China.

China, especially the densely populated North China region, experienced severe haze events in the past decade that concerned the public. Although the most extreme cases have been largely eliminated through recent mitigation measures, severe outdoor air pollution persists and its environmental impact needs to be understood. Severe indoor pollution draws less public attention due to the short visible distance indoors, but its public health impacts cannot be ignored. Herein, we assess the trends and impacts of severe outdoor and indoor air pollution in North China from 2014 to 2021. Our results demonstrate the uneven contribution of severe hazy days to ambient and exposure concentrations of particulate matter with an aerodynamic diameter <2.5 (PM2.5). Although severe indoor pollution contributes to indoor PM2.5 concentrations (23%) to a similar extent as severe haze contributes to ambient PM2.5 concentrations (21%), the former's contribution to premature deaths was significantly higher. Furthermore, residential emissions contributed more in the higher PM2.5 concentration range both indoors and outdoors. Notably, severe haze had greater health impacts on urban residents, while severe indoor pollution was more impactful in rural areas. Our findings suggest that, besides reducing severe haze, mitigating severe indoor pollution is an important aspect of combating air pollution, especially toward improving public health.

Evaluation of Available Safety Egress Time (ASET) in Performance-Based Design (PBD) Using CFAST

In South Korea, the need to link fire and evacuation simulations to compare the available safety egress time (ASET) and required safety egress time (RSET) in real time when implementing performance-based design in buildings is increasing. Accordingly, the Consolidated Model of Fire Growth and Smoke Transport (CFAST) has been discussed as an alternative to the fire dynamics simulator, which requires high computational costs, sufficient experience in fire dynamics numerical calculations, and various input parameters and faces limitations in integration with evacuation simulations. A method for establishing a reasonable computational domain to predict the activation times of smoke and heat detectors has been proposed. This study examined the validity of using CFAST to predict factors relevant to the ASET evaluation. The results showed that CFAST, which solved empirical correlations based on heat release rates, predicted high gas temperatures similarly. Moreover, the applicability of the visibility distance calculation method using smoke concentration outputs from CFAST was examined. The results suggest that despite the limitations of the zone model, CFAST can produce reasonable ASET results. These results are expected to enhance the usability of CFAST in terms of understanding general fire engineering technology and simple fire dynamics trends.

Study on the Enrichment of Pavement Marking Width and Retroreflectivity on Elderly Drivers’ Safety

Drivers’ visual function and cognitive ability deteriorate with age, and road marking improvements can better meet the driving safety and comfort needs of elderly drivers. To provide an optimal solution for marking setup and management for a large elderly community, the specific enrichment of marking width and retroreflective luminance coefficient on the driving safety of elderly drivers is investigated through an outdoor real-vehicle experiment. Twelve elderly drivers were randomly selected as experimental participants to visually detect the markings under the illumination of the vehicle high beam, and the visible distance data of white 10, 15, and 20 cm wide markings with retroreflective luminance coefficients ranging from 33 to 420 mcd.m−2.lx−1 were collected. The results showed that the visual detection ability of elderly drivers to pavement markings was significantly affected by the width and the retroreflective luminance coefficient of the markings and the enrichment of width on the detection ability of elderly drivers gradually increased with the increase of the width of markings, but the enrichment of the retroreflective luminance coefficient on the detection ability of elderly drivers gradually decreased with the increase of the retroreflective luminance coefficient of markings. The logarithmic function models of the retroreflective luminance coefficient of markings and the detection distance of elderly drivers with different marking widths were obtained by fitting. The results can provide a technical reference for proposing alternative countermeasures for the design, maintenance, and updating of pavement markings based on meeting elderly drivers’ safety with respect to economic cost and low carbon.

Free space optics communication system design using iterative optimization

Abstract Free Space Optics (FSO) communication provides attractive bandwidth enhancement with unlicensed bands worldwide spectrum. However, the link capacity and availability are the major concern in the different atmospheric conditions. The reliability of the link is highly dependent on weather conditions that attenuate the signal strength. Hence, this study focuses to mitigate the weather and geographic effects using iterative optimization on FSO communication. The optimization maximizes the visibility distance while guaranteeing the reliability by minimizing the Bit Error Rate (BER). The wireless optical communication system is designed for the data rate of 10 Gbps. The performance of the proposed wireless optical communication is compared against the literature in terms of visibility distance, quality factor, BER, and Eye diagram at different atmospheric conditions. The simulation results have shown that the proposed work has achieved better performance.

Analysis Of In-service Traffic Sign Visual Condition: An Overview

This paper offers a comprehensive review of methodologies to assess the visual condition of traffic signs. It explores image processing, machine learning, and computer vision techniques to evaluate degradation, readability, and overall visibility. The objective is to enhance maintenance and effectiveness of traffic sign systems for safer roads. Regular assessment of traffic signs is vital for their efficacy and safety, considering factors like damage, fading, obstruction, and placement. Addressing these issues can significantly enhance road safety by enabling precise and safe navigation for drivers. The study delves into various aspects including shape, background color, symbol color, temperature, land use, visibility distance, and prevailing visibility conditions of traffic signs.

Impact of Illuminated Road Signs on Driver’s Perception

This study determined citizens’ perceptions and impact factors of illuminated road signs installed to ensure their visibility at night when the risk of traffic accidents is high. An ordered logit model was used to measure illuminated road signs’ impact on drivers’ perception based on the data from the citizens’ survey conducted by the Road Sign Center. According to the results, the internal (optical fiber) type variable had the highest impact, followed by the frequent fog variable and the complex road line variable. This study found that most citizens positively recognized road signs, preferred internal (optical fiber) types, and desired illuminated road signs that considered climate, environment, and road structure types. In Seoul, the importance and improvement of illuminated road signs at points where road structures are complex, such as city streets, were high. Additionally, the illuminated road sign recognition and road type variable were significant in Gyeonggi-do, which reflected the high number of citizens that commute to Seoul from Gyeonggi-do. Concerning local cities and counties and intercity roads highly affected by the climate, the impact was high at points with frequent fog. Fog affects the visibility distance, generates condensation on signs, and significantly degrades visibility. Therefore, an illuminated road sign installation method must be presented based on spatial analysis for regions vulnerable to climate, environment, and road location. Additionally, the road intersection point variable was significant in local cities and counties, which reflects the relatively lagged road infrastructure. Local cities and counties are financially poor and have numerous aged drivers; hence, central government support that considers these aspects is crucial.

Определение видимости в плане лесовозной автомобильной дороги методом наземной стереофотограмметрии

The article describes a method for determining the visibility on the roundings of logging roads based on the materials of ground-based photo and video recording. The essence of this method is to compare the spatial photogrammetric coordinates of the points of the visibility zone. The obstacle zone and the visibility zone are considered in the same photogrammetric coordinate system, and the design center of this system coincides with the left end of the photovideo recording basis. Studies are given to determine the magnitude of the visibility distance on the horizontal curves of logging roads in the presence of an obstacle in relation to the normal case of shooting. Measures to improve traffic conditions on the roundings of logging roads in the event of a complete or partial lack of visibility are also considered. In the course of the research, dependences were obtained to determine the value of the visibility distance by the method of ground-based stereophotogrammetry, in relation to horizontal curves in the road plan; the assessment of the accuracy of determining the distance of visibility based on the materials of ground-based stereophotogrammetry was carried out. In the case of lack of visibility on the horizontal curves of roads, dependencies are proposed to determine the area and volume of the cut, and dependencies are established to assess the accuracy of the measurements performed.

Stability and Bautin bifurcation of four-wheel-steering vehicle system with driver steering control.

In this paper, the stability and Bautin bifurcation of a four-wheel-steering (4WS) vehicle system, by considering driver steering control, are investigated. By using the central manifold theory and projection method, the first and second Lyapunov coefficients are calculated to predict the type of Hopf bifurcation of the vehicle system. The topological structure of Bautin bifurcation, a degenerate Hopf bifurcation of the 4WS vehicle system, is presented in parameter space, and it reveals the dynamics of the vehicle system of different choices of control parameters. The influences of system parameters on critical values of the bifurcation parameter are also analyzed. It is shown that with the increase in the frontal visibility distance of the driver control strategy coefficient and the cornering stiffness coefficients of rear wheels, the critical speed increases. Nevertheless, the critical speed decreases with the increase in the distance from the center of gravity of the vehicle to the front axles, Driver's perceptual time delay, and cornering stiffness coefficients of the front wheels.

Safety First—A Critical Examination of the Lights and Shapes in COLREGs

According to The International Regulations for Preventing Collisions at Sea, 1972, ships can only determine their collision avoidance responsibilities in accordance with the rules of “Conduct of Vessels in Sight of One Another” if the dynamic and category of the target ship is identified to be using lights and/or shapes during encounters at sea. Then, appropriate actions can be taken, and the effectiveness of the collision avoidance actions can be checked during the subsequent maneuvering process. In order to analyze and solve the problems related to lights and shapes and to adapt to the development of ship size, speed, and intelligence, this paper firstly reviews the development history and revision process of lights and shapes. Furthermore, it explains the collision avoidance responsibility of ships in sight of one another, analyzes the role of lights and shapes in the collision avoidance process, and summarizes the lights and shapes displayed by different categories of ships. Next, through qualitative and quantitative analysis, the relationship between the visibility distance of lights and shapes and the timing of ship avoidance actions is examined. Finally, the paper points out current problems related to lights and shapes, including: (1) non-uniform visibility distance of lights, (2) insufficient visibility distance of lights, and (3) small size of shapes, and proposes solutions to these problems from theoretical and practical perspectives, including: (1) unifying the visibility distance of masthead light, sidelights, and sternlight to 6 nautical miles, (2) unifying the visibility distance of the sternlight to 3 nautical miles, and (3) unifying the diameter size of shapes and the vertical distance between shapes to 1.8 m.

Weathers effect on the free space optics communication system

Unlicensed spectrum is used in free space optics (FSO) communication, significantly increasing available bandwidth. Regardless of the weather, the most immediate concern is the link's performance and availability. Changes in the weather might impact the reliability of the link substantially. As a result, iterative optimization is being used to reduce the impact of weather and geography on FSO communication. In addition to enhancing visibility, this enhancement also reduces the bit error rate (BER). The system's wireless optical communication technology supports a data rate of up to 10 Gbps. The proposed wireless optical communication performance is compared to existing technologies regarding the visible distance, quality factor, BER, and eye diagram in various meteorological circumstances. Simulations show that the proposed work is more efficient.

Development of antenna system of a new generation tropospheric communication station

Today, means of tropospheric communication play an important role in the organization of communication at distances significantly greater than the distance of direct visibility. The peculiarities of the construction of such lines, in contrast to line-of-sight radio lines, are related to the peculiarities of the propagation of ultrashort waves and their reflection from the inhomogeneities of the troposphere. At the same time, the use of tropospheric stations makes it possible to provide high-quality multi-channel communication at an interval of 150–250 km, while significantly reducing the time for deploying long-distance lines. Along with the advantages, tropospheric means of communication have rather bulky antenna devices and require a significant energy resource. In connection with this, the task of increasing energy efficiency due to the development of antenna systems of tropospheric communication stations that will meet the set requirements arises. In order to solve the problem, a parabolic antenna (a mirror with a diameter of 1.5 m) and two types of irradiators (a linear polarization irradiator and an array of 8 elementary circular polarization irradiators) were proposed as antenna systems for tropospheric communication stations. Verification of the adequacy of the proposed antennas and the possibility of their use on real means of tropospheric communication was carried out in a collimator chamber. In order to confirm the results of the inspection, field tests of the developed antenna system of the tropospheric station were conducted at an interval of 155 km. At the same time, the combined use of the proposed antenna systems for the 80 W transmitter allows for the necessary energy of the tropospheric communication line in the frequency range of 4.5-4.7 GHz.

A Study on the Effectiveness of SCD Seeding Fog Dissipation Mechanism Using LiDAR Sensor

Fog interferes with traffic flow and causes major accidents. In foggy conditions, traffic accident death rates are higher than in other weather conditions. Research on fog dissipation technology is needed to reduce the incidence of accidents caused by fog. There are various artificial methods to remove fog. In this study, two methods of natural dissipation by gravity sedimentation and a solid carbon dioxide seeding fog dissipation mechanism were compared and analyzed in cold fog conditions. Solid carbon dioxide was selected as the fog dissipation particle. In this experiment, solid carbon dioxide seeding with three different values of weight (500 g, 1000 g, and 1500 g) was considered. This is because fog particles can be supercooled and fog can be removed. A light detection and ranging (LiDAR) sensor were used to quantitatively check the effect of improving visibility when solid carbon dioxide was seeded in the fog. The LiDAR sensor detects the surrounding environment through distance measurements by emitting lasers and processing the laser responses. A camera was used to visually observe the phenomenon occurring inside the calorimetric chamber. As a result, the fog dissipation mechanism using solid carbon dioxide seeding under cold fog conditions was proven to be effective in improving the visible distance compared with natural dissipation.

Ultrasensitive Detection of miRNA via CRISPR/Cas12a Coupled with Strand Displacement Amplification Reaction.

MicroRNA (miRNA) is a promising biomarker for the diagnosis, monitoring, and prognostic evaluation of diseases, especially cancer. The existing miRNA detection methods usually need external instruments for quantitative signal output, limiting their practical applications in point-of-care (POC) settings. Here, we propose a distance-based biosensor through a responsive hydrogel, in combination with a CRISPR/Cas12a system and target-triggered strand displacement amplification (SDA) reaction for visual quantitative and sensitive measurement of miRNA. The target miRNA is first converted into plenty of double-stranded DNA (dsDNA) via target-triggered SDA reaction. Then, the dsDNA products trigger the collateral cleavage activity of CRISPR/Cas12a, leading to the release of trypsin from magnetic beads (MBs). The released trypsin can hydrolyze gelatin, and hence the permeability of gelatin-treated filter paper is increased, resulting in a visible distance signal on a cotton thread. Using this system, the concentration of the target miRNA can be quantified visually without any assistance of instruments, and a detection limit of 6.28 pM is obtained. In addition, the target miRNA in human serum samples and cell lysates can also be detected accurately. Owing to the characteristics of simplicity, sensitivity, specificity, and portability, the proposed biosensor provides a new tool for miRNA detection and holds great promise in POC applications.

Ring exploration of myopic luminous robots with visibility more than one

We investigate ring exploration algorithms for autonomous myopic luminous robots. We consider the constraint that the visible distance is any constant of at least two and the number of colors of light devices is two. As a main contribution, in the fully synchronous, semi-synchronous, and asynchronous models, we prove that 1) two robots are necessary and sufficient to achieve perpetual exploration and 2) three robots are necessary and sufficient to achieve terminating exploration. These results show the power of large visibility for luminous robots because, when the visible distance is one and the number of colors is two, three and four robots are necessary to achieve perpetual and terminating exploration, respectively, in the semi-synchronous and asynchronous models. We also show that the proposed perpetual exploration algorithm is universal. On the other hand, we show that no universal algorithm exists for terminating exploration with three robots.