Foggy Area Research Articles

Engineering of Hierarchical Porous Composite Film (ZIF-8@PVDF/PMMA) with Superhydrophobicity for Highly Efficient Water Harvesting.

Atmospheric water harvesting has attracted much attention because of its potential to escalate the global freshwater shortage. However, the water collection efficiency is hindered by the trade-off between fast droplet nucleating and rapid droplet dripping due to the opposite requirements in the chemistry and the morphology of surfaces. Herein, the hierarchical porous composite film (ZIF-8@PVDF/PMMA, HPCF) with superhydrophobicity is designed for highly efficient and stable water harvesting. It indicates that the HPCF film has a large water contact angle (WCA) of 155.50° and ultralow sliding angle (SA) of 2°, exhibiting the self-cleaning function. Significantly, it is demonstrated that the water collection efficiency of HPCF can achieve 1.13 g·cm-2·h-1, which is much higher than the value of the blank sample, as well as most of the reported values. It is attributed to the hierarchical porous structure with the ZIF-8 crystals enhancing the surface roughness and endowing the film with the hydrophilic/superhydrophobic regions. This design promotes an optimal balance between droplet nucleation and shedding, significantly enhancing the water harvesting efficiency. Consequently, this work introduces an effective approach for water collection materials suitable for fog/mist conditions and provides an effective solution for the foggy area with water scarcity, demonstrating significance for advancing research aimed at mitigating the worldwide water shortage.

Fog water harvesting with cylindrical brush

In this study, an efficient fog collector—type 1 and 2 cylindrical brush—has been introduced and its harvesting performance compared to other conventional collectors under field and laboratory conditions. Under field conditions, type 1 cylindrical brush with Raschel and aluminum mesh was installed in the inlet of the humidity front of the Caspian Sea to Ardabil plain in Abi-beyglu in the northwest of Iran. The results of the analysis of the collected water revealed that type 1 cylindrical brush collected 9.3% and aluminum mesh collected 4.3% more water than Raschel mesh. Under laboratory conditions, by applying different fog speeds, the performance of three conventional collectors and two proposed cylindrical brush were determined. The results indicated that type 2 cylindrical brush had the highest efficiency compared to others, and due to the lack of clogging, its efficiency did not diminish over time. Upon increasing the speed of the output fog, the amount of collected water and accordingly the efficiency of the collectors increased. Type 2 cylindrical brush showed the highest increase in efficiency at high fog speeds. Its maximum value reached about 50%, while the maximum efficiency of Raschel collector was equal to 28%. In general, it can be stated that cylindrical brush introduced in this study, in addition to the high performance of fog harvesting and the high efficiency of water collection, has a high resistance against strong winds. Therefore, it can be a suitable collector for water harvesting in foggy areas without any implementation problems.

Research progress of bionic fog collection surfaces based on special structures from natural organisms.

With the increasing shortage of water resources, people are seeking more innovative ways to collect fog to meet the growing need for production and the demand for livelihood. It has been proven that fog collection is efficient for collecting water in dry but foggy areas. As a hot research topic in recent years, bionic surfaces with fog collection functions have attracted widespread attention in practical applications and basic research. By studying natural organisms and bionic surfaces, more avenues are provided for the development of fog collection devices. Firstly, starting from biological prototypes, this article explored the structural characteristics and fog collection mechanisms of natural organisms such as spider silk, desert beetles, cactus, Nepenthes and other animals and plants (Sarracenia, shorebird and wheat awn), revealing the fog collection mechanism of the natural organisms based on microstructures. Secondly, based on the theory of interfacial tension, we would delve into the fog collection function's theoretical basis and wetting model, expounding the fog collection mechanism from a theoretical perspective. Thirdly, a detailed introduction was given to prepare bionic surfaces and recently explore fog collection devices. For bionic surfaces of a single biological prototype, the fog collection efficiency is about 2000-4000 mg cm-2 h-1. For bionic surfaces of multiple biological prototypes, the fog collection efficiency reaches 7000 mg cm-2 h-1. Finally, a critical analysis was conducted on the current challenges and future developments, aiming to promote the next generation of fog collection devices from a scientific perspective from research to practical applications.

Driving behavior of L3 autonomous vehicle drivers in fog zones under different traffic flow conditions

The foggy freeway is a scenario with a high incidence of accidents. Different traffic flow conditions will affect the driving behavior of conditionally autonomous vehicle drivers in the foggy areas of the freeway. In this study, the experiment was carried out by using the driving simulation system. Forty-two participants drove on a foggy freeway according to two traffic conditions and two non-driving related tasks. Wilcoxon Signed-Rank Test and Survival Analysis were applied to explore the impact. The results show that the effects of different non-driving related tasks on driving behavior are mainly concentrated in the takeover process; The deceleration reaction time of the free flow (6.04 s) is much lower than that of bound flow (9.40 s); In the condition of bound flow, the driver is more inclined to slow down without braking. Potential application areas of this research comprise safety assessment of conditional autonomous driving and formulating autonomous driving policy.

Impact of Feature-Dependent Static Background Error Covariances for Satellite-Derived Humidity Assimilation on Analyses and Forecasts of Multiple Sea Fog Cases over the Yellow Sea

Assimilation of satellite-derived humidity with a homogenous static background error covariance (B) matrix computed over the entire computational domain (Full-B) tends to overpredict sea fog coverage. A feature-dependent B (Fog-B) is proposed to address this issue. In Fog-B, the static error statistics for clear air and foggy areas are calculated separately using a feature-dependent binning method. The resultant error statistics are used simultaneously at appropriate locations guided by the satellite-derived sea fog. Diagnostics show that Full-B generally has broader horizontal and vertical length scales and larger error variances than Fog-B below ~300 m except for the vertical length scale near the surface. Experiments on three sea fog cases over the Yellow Sea are conducted to understand and examine the impact of Fog-B on sea fog analyses and forecasts. Results show that using Full-B produces greater and broader water vapor mixing ratio increments and thus predicts larger sea fog coverage than using Fog-B. Further evaluations suggest that using Fog-B has greater forecast skills in sea fog coverage and more accurate moisture conditions than using Full-B.

Atmospheric conditions conducive to marine fog over the northeast Pacific in winters of 1979–2019

Observations show that the northeast Pacific (NEP) is a fog-prone area in winter compared with the northwest and central Pacific where fog rarely occurs in winter. By synthesizing observations and reanalysis results from 1979 to 2019, this study investigates the atmospheric circulation and marine atmospheric boundary layer structure associated with marine fog over the NEP in winter. Composite analysis shows that the eastern flank of the Aleutian low and the northwestern flank of the Pacific subtropical high jointly contribute to a northward air flow over the NEP. Under such conditions, warm and moist air flows through a cooler sea surface and facilitates the formation of advection-cooling fog. The air near the sea surface in foggy areas is cooled by the downward sensible heat flux. The smaller upward latent heat flux (∼10 W m−2) compared to the surrounding area (>60 W m−2) demonstrates that the moisture originates from the advection instead of local evaporation. The lower (at 925 to 875 hPa) and stronger (up to 0.08 K hPa−1) inversion layer, compared with cloudy cases and the turbulence in the lower atmosphere (below 975 hPa), also promotes fog formation and evolution. Approximately 68% of all fog cases (42242) show positive differences between surface air temperature (SAT) and sea surface temperature (SST), while 32% are negative, during southerly winds. Composite analysis of the latter shows lower specific humidity above the inversion bottom compared to the former. Dry air enhances longwave radiative cooling from the fog top, favoring cooling of the fog layer, gradually causing SAT to fall below SST.

Fog Harvesting Devices Inspired from Single to Multiple Creatures: Current Progress and Future Perspective

AbstractThe increasing demand for clean water driven by the rapid growth of the population and the pollution of water necessitates the development of direct and rapid water harvesting methods. Fog harvesting is proven as a highly efficient water capture method in dry but foggy areas. Herein, the state‐of‐the‐art developments on the multiple biomimetic fog harvesting devices (FHDs) are presented. First, the fundamental and specific mechanisms of fog harvesting involving the Namib Desert beetle, spider silk, cactus, and Nepenthes alata are described in detail, respectively. Second, an in‐depth discussion on the mechanisms of fog harvesting including fog capture and water transport is proposed. Third, a detailed account of the innovative design strategies and fabrication technologies of FHDs is proposed, from single to multiple biomimetic FHDs with typical examples and the merits and demerits are compared. Finally, a critical analysis of current challenges and future development is presented, aiming to promote next‐generation FHDs from scientific research to practical application.

Research on the influence of light source characteristics on traffic visual distance in foggy areas at night

Adverse weather such as fog will reduce drivers' visual recognition ability, and important visual information in the driving will be weakened and even lost, which brings risks to driving safety. This paper sets out to explore causes for the decline in driving visual ability in foggy sections at night based on drivers' visual recognition demand mechanism. The purpose is to study the influence of light source characteristics on visual distance under open traffic conditions. Through an outdoor visual recognition test, data were collected on the visual recognition distances of 12 car drivers to standard gray small targets, under different light source characteristics and meteorological visibility conditions. Results revealed that the latter conditions, along with illuminance and correlated color temperature affected drivers' visual recognition ability in low meteorological visibility sections at night. At the same illuminance and meteorological visibility, a light source with high correlated color temperature could improve visual distance. The multivariate power function model of meteorological visibility, illuminance at the target and driver's visual distance in foggy areas were obtained by fitting. The research methods and conclusions could provide technical reference for improving traffic visual distance at night, and thus help lay a foundation for road construction and traffic control technology in foggy areas.

Monochromatic Leds For Vision Improvement in Foggy Roads

In India, foggy weather creates poor visibility, and this leads to several accidents and slows down normal traffic speed, which may lead to adverse effect on the economy of the country. The probable solution is the use of monochromatic light with other artificial vision system to increase the visibility for the drivers in these foggy areas. There are various kinds of monochromatic lights available in the market. In this study, it has been tried to find out the best working monochromatic LEDs for this particular application. In this study, two types of monochromatic radiation were compared (amber light with 600 nm and green light with 545 nm) with and without the camera-display setup (artificial visual system) for finding out best working system in the foggy area for increasing the visibility. The experiment shows that amber light monochromatic radiation with 600 nm works better for identification of objects. The amber light can be used in front of a car to illuminate the front environment in the foggy weather and increase the visibility. It has been observed that green light monochromatic radiation with 545 nm works better for identification of the source from a very long distance. It has been proposed to install both of these lights with amber and green monochromatic radiation in vehicles to reduce accidents in foggy weather.

Correlation between visibility and traffic safety visual distance in foggy areas during the daytime

Objective Traffic safety is closely related to the driver's ability to obtain visual information. Low visibility would result in traffic accidents. This study aimed to explore the difference between meteorological visibility and traffic safety visual distance in foggy areas in the daytime, and analyze the difference between dynamic visual ability and static visual ability, so as to calculate the maximum acceptable speed limit that meets the driver's safety visual distance requirement. Methods Visual distances under different visibility conditions were collected for 12 passenger car drivers through static and naturalistic driving visual recognition experiments. The power function relation model between driver's static visual distance and meteorological visibility was established, and the attenuation rates of dynamic visual distance at different driving speeds were obtained. Results Traffic safety visual distance (TSVD) gradually grows with the increase of visibility and finally tends to be stable due to the vision limitation of the human eyes under good weather conditions. The drivers' visual ability decreased while driving dynamically, and dynamic TSVD was shorter than static TSVD. Conclusions Traditional meteorological visibility is different from drivers' actual TSVD, but there is a correlation between them. According to the relationship between visibility and dynamic TSVD, the maximum recommended speed limit values under different visibility levels are provided. The calculation of the maximum acceptable speeds under specific visibility conditions can provide a technical basis for road construction and traffic management.

Secure controlling system for cross layer reliability for ultra huge scale framework

Ultra wideband (UWB) radio ascends as an attractive physical layer for extraordinarily chosen frame (MANET) adaptability. Guiding in MANET is a study that can be inferred from the vibrant thinking of the topology system and the impediments to resources. In this document, UWB is proposing a stable coordination structure concentrating on the flimsiness problem from the foggy area of communication. This tool is a cross-layer shift of tradition-controlled uncommonly delegated on-ask for vector (AODV), called CLS AODV. The managing exposure calculation is associated by showing source planning and extraordinarily chose on-request multipath remove vector (AOMDV) organizing. Rather than the open way in AODV, the got sign quality can be used to reveal shady territory wish affiliation state data, just as course state seeing. A preventive neighborhood fix course gauge dependent on HELLO knows about keeping the affiliation breakage event. Greetings notification is extended not only for neighborhood identification and exchange of neighborhood data, but also as an ON / OFF fee for controlling neighborhood location layout and HELLO design. The proliferation shows the progression of CLS AODV to the extent of the package incident and the typical end-to-end acknowledgement without exchanging the differentiated performance.

Characterization of Silicone Rubber Degradation Under Salt-Fog Environment With AC Test Voltage

In recent years, some composite insulators operating in coastal foggy areas have shown different levels of degradation phenomena. This paper presents several performances and properties of silicone rubber under the salt-fog environment with AC voltage. Analysis conducted after salt-fog treatment by techniques, such as static contact angle, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), dielectric parameter, and flashover voltage show a significant degradation of samples. The absorption peak of the hydrophobic groups (Si-(CH3)2 and Si-CH3) decreased, the surface of the material became rough, and the dielectric and electrical properties were also deteriorated. Due to the thermal effects and impact of high-energy particles, the molecular chains on the surface of silicone rubber were broken, and the smooth surface structure was destroyed, resulting in the formation of hydrophilic chemical bonds and precipitation of inorganic substances. The intrusion of moisture further reduces the dielectric parameters and the electrical strength of the material. In addition, the samples in the salt-fog environment with a greater conductivity are more degraded, indicating that the salt-fog has an aggravating effect on the aging of the silicone rubber. Thus, it is recommended to pay attention to the monitoring and examining the work of composite insulators operating in a foggy and high humidity environment.

Heterogeneous Fog Generated with the E ect of Light Scattering and Blur

The development of computer graphics forces new requirements on the developers, which will make the virtual world more similar to the real world. One of these elements is the simulation of fog. Common fog algorithms mix the color of the scene with the color of the fog over a certain distance. However, one feature of the naturally foggy scenery is ignored. With the distance and density of the fog, the observed scenery or individual objects become more blurred. In this paper we will present our implementation of the distance fog in the Unreal Engine 4, including the effect of blurring the foggy areas, simulating of light scattering and variations in fog density using noise.

RADIATIVE TRANSFER MODEL SIMULATIONS TO DETERMINE THE NIGHT TIME FOG DETECTION THRESHOLD

Abstract. Every winter the Indo-Gangetic plains (IGP) of northern India are severely impacted both socially and economically by fog. For night time fog detection, visible imagery cannot be used. Also, as emissions from ground and fog is almost similar in thermal infrared (TIR, 10.8 μm) channel, TIR channel cannot help in identifying fog. However, emission in middle infrared (MIR, 3.9 μm) channel is less than emission in TIR channel over foggy area. Therefore, brightness temperature difference (BTD) between TIR and MIR is positive during night time over fog area. This BTD technique cannot be directly used during day time as MIR channel is contaminated by solar radiations. In the present work, a spectral sensitivity analysis study has been done for these two spectral channels using radiative transfer model (RTM) simulations to determine a threshold BTD for night time fog detection. SBDART (Santa Barbara DISORT Radiative Transfer) model was used for this study to simulate brightness temperatures (BT). The RTM simulations of BT of the two spectral channels was carried out for different fog microphysical characteristics like fog optical depth (FOD) and fog droplet size (Re). The fog episode of January 2018 over IGP was studied by applying threshold BTD obtained from simulation results for INSAT-3D data. A threshold BTD value > 5 K detected night time fog over IGP with good accuracy. The threshold BTD obtained from satellite image is compared with different cases established from simulation result which gave idea about microphysical properties of fog over IGP during winter seasons.

Optimization of Image Enhancement Algorithm in Foggy Area

Nowadays, tourism scenic area gradually become people to relax, one of the best place to rest, the huangshan mountain, the Yellow River and other famous scenic spots, for example, however, at present, most of the scenic area in the design of the monitoring equipment does not consider the influence of the bad weather, so under the condition of rain day, under the influence of atmospheric scattering function monitoring equipment, unable to capture the image; At the same time, monitoring equipment working for a long time, more or less there will be a certain degree of degradation. Therefore, this article on the basis of defects based on the existing scenic spot to fog, mainly focus on a single scale fog image enhancement algorithm Retinex algorithm and multiscale Retinex algorithm concept, and gives the specific process of two kinds of algorithm of Matlab programming, through the analysis judgment, evaluation and prediction, and plenty of experimental data and theoretical support, through a large number of experiments, the results prove multiscale Retinex algorithm in image contrast to the scenic spots in the fog effect is best, in the process of use in the future to the scenic spot of fog, can get the desired effect.

Modeling the effect of limited sight distance through fog on car-following performance using QN-ACTR cognitive architecture

This study explored human error risk factors in car-following behaviors, cognitive resource bottlenecks and performance impairment mechanisms in the context of cognitive capacity while driving on foggy roads. Firstly, a hierarchical driving behavior assessment was used to observe risky driving behavior in a foggy area. A driver's dynamic speed adjustment analog experiment was carried out in foggy conditions. Unique parameters were substituted into the traditional QN-ACTR driver behavior model. The visual far-time of the traditional model and the latitude-longitude control sensitivity parameters were estimated. Foggy conditions were modeled based on the QN-ACTR cognitive architecture to observe the effect of limited sight distance through fog on car-following performance. Jsim in the Eclipse environment and TORCS were applied in co-simulation and verified. The results show that (1) the proposed cognitive modeling approach effectively simulates a foggy driving environment and allows researchers to study affected and related driver behavior; and (2) the car-following performance in low visibility is significantly worse than in high visibility. These findings provide theoretical support and a scientific basis for the study of speed, safe distance, standard of limited speed and design methods for engineering safety mechanisms to counter the negative effects of driving on foggy roads. This study can inform actions to increase road safety during fog.

Are Dracaena nebulophytes able to drink atmospheric water?

In arid and semi-arid environments, fog interception as a water acquisition mechanism has been long recognized as an important factor for plant survival. The “narrow-leaf syndrome” increases water absorption from horizontal precipitation and is typical of nebulophytes characterized by dense rosette type crowns, to which also Dracaena species belong. In this paper, we demonstrate that Dracaena nebulophytes are able to direct water intercepted from fog through the leaf axils into their succulent woody organs to be stored for later use. We conducted leaf axil watering (LAW) experiments in four young Dracaena plants (two Dracaena cinnabari and two Dracaena draco) while simultaneously measuring sap flow in plant stems using the heat field deformation method. It was assumed that inducing water potential within stems closed to zero would initiate simultaneous bidirectional water transport from the stem to the crown and roots, and that this moment would be reflected in corresponding sap flow. Three hypothetical scenarios of induced water transport imbalance were confirmed by analyzing measured temperature gradients around heated probes and calculating sap flow. Sap flow responses to LAW clearly appeared to be dependent on flow direction prior to water treatments, on the strength of forces driving upward and downward water movement and the quantity of water applied. Intrinsic sap flow changes depicted in the results confirm the hypothesis that the Dracaena species are able to direct atmospheric water through the axils of their leaves to stem tissues. This mechanism of bypassing soil water represents an alternative means of water uptake in plants and is especially important in foggy areas of arid and semi-arid climates.

Isotopic assessment of fog drip water contribution to vegetation during dry season in Junshan wetland, northern Dongting Lake

Stable isotopes 2H and 18O of fog drip water, lake water, soil profiles, and vegetation leaves in Junshan wetland of East Dongting Lake, China, were investigated to estimate the contribution of fog drip water to wetland vegetation. Because of its recycled terrestrial meteoric water source, fog drip water is characterized by isotopic compositions that plot above the local meteoric water line (LMWL). Lake water undergoes intense evaporation owing to its low water volume and long residence time. The isotopic compositions of soil water suggest that it is recharged by both recent rainfall and fog drip water. A binary mixing model shows that approximately 16% of unsaturated soil water originates from continuous recharge by fog drip water, reaching 31% in surface soil where the vegetation roots are mainly distributed. Inspired by the literatures on acidification of intercepted clouds and fog as the major factor in forest die-back in Europe, the findings in this study inform future investigations into the relationships between fog water deposition and wetland degradation especially in heavily industrialized foggy areas.

Study and implementation of the LED headlight driver with auto‐start function in specific location

Conventional automatic headlight devices determine whether to switch vehicle headlights on or off according to the brightness of the environment. These devices cannot automatically switch on headlights during daytime unless the headlights are required in specific road conditions (e.g. mountainous or foggy areas), thus compromising the safety of road users and drivers. This study develops a light-emitting diode (LED) headlight system that integrates the global positioning system (GPS) and a controller area network (CAN) bus communication interface. This system uses the GPS system to analyse the geographic location and then determines whether to switch on the LED headlight. To reduce the system complexity, a CAN bus is used to limit the number of control wires required. The LED headlight driver also uses an interleaved boost converter that has low conduction losses and input ripple currents, which improves the conversion efficiency of the headlight drivers and extends the battery lifetime. The feasibility of the proposed technology is verified using experimental results.

Gas turbine air filter elements under fog endurance tests

Pulse-jet filter systems for gas turbines installed in humid and foggy areas rarely achieve their promised life-time. Here, we look at test methods to evaluate fog endurance of filter elements under laboratory conditions.