Threshold Zone Research Articles

Influence of an adjacent tunnel connecting zone shading shed on drivers’ eye movement characteristics

A tunnel shading shed is crucial in improving driving safety as a type of traffic facility to ease the transition of light environments. To study the effect of installation of a shading shed on the visual characteristics of drivers in the connecting zone of the adjacent tunnels, a total of 32 drivers were gathered to perform a real vehicle experiment. The study zone of the adjacent tunnels was divided into three sections: upstream tunnel exit; connecting zone; and downstream tunnel threshold zone. Fixation duration, saccade duration and saccade frequency were selected as research indexes. The results suggest that installation of a shading shed in the connecting zone significantly reduced the fixation (saccade) duration in the upstream tunnel exit and downstream tunnel threshold zones, with a significantly higher saccade frequency. In addition, fixation is better improved at the downstream tunnel entrance, and saccade is better enhanced at the upstream tunnel exit.

Effects of Endurance Training on Antioxidant and Hormonal Status in Peripheral Blood of Young Healthy Men.

(1) Background: Physical activity may cause an imbalance in the major functions of the human body. This study aimed to investigate the effects of endurance running training on the parameters of the antioxidant defense system (SOD, CAT, GPx, GR, GSH), LPO (malondialdehyde, MDA), and stress hormones (A, NA) in young healthy, previously untrained men. (2) Methods: The training program was as follows: 8 weeks of running, three times per week; the duration of a single session was 30-70 min, the intensity was twice a week in the so-called extensive endurance zone, and once a week in the anaerobic threshold zone. Blood samples were collected from the subjects, before and after the running program. (3) Results: The training program resulted in a significant increase in maximal oxygen consumption (p < 0.001). The activities of SOD, GPx, and GR also increased significantly (p < 0.05, p < 0.01, and p < 0.05, respectively), while CAT activity and GSH and MDA concentrations remained unchanged. The concentration of A decreased (p < 0.05), while the NA concentration increased significantly (p < 0.05). SOD, GPx, GR, and NA positively correlated with VO2max (p < 0.05, p < 0.001, p < 0.01, p < 0.05, respectively), while a negative correlation was detected between A and VO2max (p < 0.05). (4) Conclusions: These results indicate that there is no persistent oxidative stress in response to the applied 8-week running program, probably due to exercise-induced protective alterations in the antioxidant defense system. Furthermore, adaptations occurred at the hormonal level, making the organism more ready for a new challenge.

Modeling Night and Daylighting Toll Road Tunnel Using Dialux to Compare the Performance of HPS and LED Lamp

In toll road tunnels, the lighting at the threshold zone must balance the brightness of the access zone with natural light. Therefore, artificial lighting is strategically placed in that area to match the brightness to the intensity of natural light. This balance shifts during nighttime to ensure uniform brightness throughout the tunnel, equivalent to street lighting. Additionally, a significant amount of power is required to realize this artificial lighting. Two lamp technologies are used for tunnel lighting: HPS lamps with low energy efficiency and LED lamps with better energy efficiency. The challenge is determining artificial lighting in the threshold zone using energy-efficient lamps. To address this issue, simulations were conducted to compare the two lamp types applied in tunnels to achieve the most significant power savings. This research creates a model of toll road tunnel lighting using DIALux software better to understand the characteristics of toll road tunnel lighting using HPS and LED lamps. The SNI and ANSI/IES are the standards used. The Cisumdawu tunnel is used as the case study. The simulation results show that the luminance in the interior zone using LED or HPS lamps meets the SNI standard. Using LED lamps results in higher luminance with less power than using HPS. This discovery can improve energy efficiency in tunnel environments and contribute to lighting solutions for transportation infrastructure.

Energy saving in road tunnels by means of transparent tension structures

The high and constant rate of energy consumption in road tunnels has led researchers to look for more and more efficient lamps and luminaries. The solutions developed have partially contributed to energy saving but consumption is still high, specially in the threshold zone which requires very high levels of luminance, and the solutions found still have important contras like colour performance. In this work, we present a completely different solution: the extension of the “threshold zone” out of the tunnel by means of a transparent tension structure to let visible solar radiation go into the tunnel and achieve the required levels of luminance during daytime without any kind of electrical lighting.

Computational Simulation versus Scale Model to determine the Optimal Shape of Tension Structures for the use of Sunlight in Road Tunnels

Placement of semi-transparent tension structures in the portal gate of road tunnels to shift their threshold zone and use sunlight, has been proved to be an interesting procedure to save electrical energy. However, in order to obtain the maximum performance, the shape of the structure has to be established for each tunnel, depending on its geographic location, orientation and surroundings. In previous works, computational methods and a scale model have been used to determine the optimal shape of these structures without expensive and time costing trials. In this work, comparison of the results is presented and it shows that the virtual modeling combined with the previously derived ESTS equation can be used to choose of the most convenient structure.

Clarithromycin Suppresses Apple Proliferation Phytoplasma in Explant Cultures.

Apple proliferation, caused by 'Candidatus Phytoplasma mali', is one of the most important economic threats in the field of apple production. Especially at a young age, infected trees can be affected by excessive bud proliferation and general decline. The fruit quality is also significantly reduced by this disease. To investigate treatment options, we applied a clarithromycin chemotherapy to infected in vitro cultures of 'Golden Delicious'. With increasing concentrations of clarithromycin in the media, the phytoplasma load decreased rapidly after one month of treatment, but phytotoxicity led to a pronounced mortality at 40 mg/L, which was the highest dose used in our experiment. Out of 45 initial explants, we obtained one negative mericlone and two mericlones with a concentration of phytoplasma DNA at the detection limit of PCR. The culture propagated from the mericlone that tested negative remained phytoplasma-free after 18 months of subculturing. Our results suggest the applicability of macrolide antibiotics against phytoplasma infections in vitro; however, it might be challenging to find the threshold zone where the concentration is sufficient for pathogen elimination, but not lethal for the plant material of different cultivars.

Transmittance optimization of tunnel shading shed for maximum energy savings and traffic safety: When replacing tunnel lighting in threshold zone

Tunnel shading shed instead of tunnel lighting is one of the ideal ways to reduce the tremendous energy consumption at the entrance (section 2.1), but at present the length of tunnel shading shed and illuminance inside tunnel shading shed rarely meet the relevant technical requirements (section 2.2). Although some literature estimated the energy saving benefits of tunnel shading shed when replacing tunnel lighting in the threshold zone (section 2.2.1), there is no study on the conditions for maximum energy saving, the impact of energy saving on safety and the energy-saving efficiency in all time and all weather. To solve the above problems, suggest a multi-objective optimization condition of transmittance for maximizing energy savings improving traffic safety (section 3.3.2). In addition, propose an efficient sunlight simulation method based on finite element partitioning (section 3.3.1), derive a formula for precise energy-saving efficiency of tunnel shading shed (section 4.2.1), and analyze factors affecting energy-saving efficiency. The results show that: Suitable transmittance can simultaneously maximize the energy savings of tunnel shading shed (section 4.2.2) and improve traffic safety in the tunnel portal area (section 4.3). And the energy-saving efficiency on sunny summer days is not the greatest. It provides the theoretical and methodological support for making full use of sunlight and saving tunnel lighting electric energy.

Assessment and optimization of tunnel lighting quality based on drivers' visual comfort: From methodology to application

Drivers' visual comfort is directly affected by tunnel lighting quality. Currently, many built tunnels have poor-quality lighting with varying degrees of visual interference, which may lead to visual discomfort and traffic accidents. To solve this problem, this study proposes a method to assess and optimize the tunnel lighting quality, aiming to evaluate the lighting quality from the perspective of drivers' visual comfort and improve the lighting effect in each lighting zone of the tunnel. First, the visual characteristics of drivers and quantitative relationship between visual comfort and tunnel lighting environment are derived through field tests and mathematical statistics. Second, the comfort range based on visual characteristic indicators (VCIs) is obtained via a comprehensive analysis of objective physiological responses and subjective questionnaire survey results of drivers, which is used as the comfort criteria to assess the tunnel lighting quality. Subsequently, the effects of luminance, luminance uniformity, and flicker frequency on drivers' visual comfort are considered, and a lighting optimization model based on the adaptive penalty function particle swarm optimization algorithm is established by combining comfort constraints and energy-saving objectives. Finally, driving simulation experiments are performed using virtual reality technology, which verify the effectiveness of the assessment and optimization methods. The results show that drivers' visual comfort in the tunnel threshold zone increases with an increase in the luminance reduction coefficient and decrease in the vehicle speed, and drivers' visual comfort in the tunnel interior zone increases with an increase in the road surface illuminance and visibility. The comfort range of the VCIs classify the tunnel lighting quality into four evaluation levels. Therefore, the proposed method can accurately and quantitatively assess the comfort of the tunnel lighting environment, improving drivers' visual comfort in the tunnel by 48.08 %, while saving 12.03 % of energy.

Improving the aerobic possibilities of qualified athletes

Improving the aerobic possibilities of qualified athletes

Parameter design of solar optical reflection lighting system array for shadowless lighting in threshold zone of short freeway tunnel

A solar optical reflection (SOR) lighting system has been developed to illuminate the threshold zone of short freeway tunnel in the premise of zero energy consumption. To improve the limited illumination performance of SOR lighting system due to the obstruction of moving vehicles on reflected sunlight rays, this study develops a fast and simple parameter design method for shadowless lighting based on an array of multiple SOR lighting systems that makes reflected sunlight emit to the threshold zone from different angles. The effectiveness of shadowless lighting is verified by the application on a two-lane freeway of Shaanxi Province, China. Results show that the shadowless lighting can significantly improve the illuminance in threshold zone, and the improvement rate is higher for the area farther from the tunnel entrance inside the tunnel. In order to achieve shadowless lighting avoid both the vehicle and inter-system blocking on reflected sunlight, the systems should be installed roadside in a staggered array that: 1) their heights descend and lateral distances from the curb shrink in turn from near to far from the tunnel entrance, with as small vertical and horizontal deflection angles of the reflectors as possible, or 2) their heights remain identical with a reduction in the vertical deflection angles of the reflectors from near to far from the tunnel entrance.

Does Lactate-Guided Threshold Interval Training within a High-Volume Low-Intensity Approach Represent the "Next Step" in the Evolution of Distance Running Training?

The aim of the present study was to describe a novel training model based on lactate-guided threshold interval training (LGTIT) within a high-volume, low-intensity approach, which characterizes the training pattern in some world-class middle- and long-distance runners and to review the potential physiological mechanisms explaining its effectiveness. This training model consists of performing three to four LGTIT sessions and one VO2max intensity session weekly. In addition, low intensity running is performed up to an overall volume of 150-180 km/week. During LGTIT sessions, the training pace is dictated by a blood lactate concentration target (i.e., internal rather than external training load), typically ranging from 2 to 4.5 mmol·L-1, measured every one to three repetitions. That intensity may allow for a more rapid recovery through a lower central and peripheral fatigue between high-intensity sessions compared with that of greater intensities and, therefore, a greater weekly volume of these specific workouts. The interval character of LGTIT allows for the achievement of high absolute training speeds and, thus, maximizing the number of motor units recruited, despite a relatively low metabolic intensity (i.e., threshold zone). This model may increase the mitochondrial proliferation through the optimization of both calcium and adenosine monophosphate activated protein kinase (AMPK) signaling pathways.

Design Method of Combined Gradient Dimming Structures for Highway Tunnels

The notable brightness difference between the inside and outside of a tunnel is a major issue restricting the safe driving and energy-saving conditions of highway tunnels. The installation of a shading structure at the entrance of a highway tunnel could resolve this problem. This method is equivalent to moving the entrance zone outside so that light is smoothly transmitted into the tunnel, which is called pretunnel lighting. In this research, the shading structure is selected as the research object. First, the shading effects of pergolas and sunshades of different cross-sectional forms are analyzed. Second, choosing the Jiulongpo Tunnel in Chongqing as an example, through DIALux software modeling and analysis, the tunnel sunshade is selected as the primary shading structure, which is better than the pergola in terms of the average luminance value and uniformity of luminance. Third, based on the idea of gradient dimming outside the tunnel, three kinds of combined gradient dimming sunshades are designed. Considering the influence of the season, weather and orientation, the optimal design scheme is determined in detail. Finally, the energy-saving benefits are calculated of the installation of a tunnel sunshade to replace the enhanced lighting in Threshold zone 1 (TH1) combined with gradient dimming lighting in Threshold zone 2 (TH2). The results show that the combined gradient dimming sunshade in Scheme 3 (70% + 40% + 20% + 10%) is optimal. The combined gradient dimming sunshade could decrease the variation in luminance inside and outside the tunnel and reduce the artificial lighting intensity in the entrance zone, which could facilitate safe driving and energy savings.

The influence of dimming-induced luminance change on driving safety in tunnels

Although dimming the light in tunnels brings salient benefits to energy saving, the effects of dimming-induced luminance changes on driving safety have been rarely explored. Adopting the visual performance experiment, the present study investigated the impacts of the dimming-induced luminance change rate (V) on the safety of driver’s perception, judgment, and operation in the threshold zone of the tunnel under different seasons and weather conditions. The results show that the reaction times (RTs), pupil area change rate (vp), and blink frequency (fb), increased with the increase of V. When the luminance before the beginning of dimming (L) was higher, drivers reacted faster and stood a lower level of the mental load and fatigue. Compared with decreasing the luminance through dimming, when increasing the luminance through dimming, the present study found that each of the visual performance indices was about 10% lower, and the changes with V became smaller. Based on the safety thresholds of RT, vp, and fb, the present study obtained the thresholds of V which can meet the safety requirements of driver’s perception, judgment, and operation. Finally, a theoretical model between the thresholds of V and L was developed, and this model will shed light on the control of V in the threshold zone of the tunnel under different seasons and weather conditions.

Reliability Enhancement Driven by ANN for Lighting Control System in Highway Tunnels

Compared with open roadways, traffic safety in highway tunnels requires more attention to build smoothly transitioned and well-coupled light environments for drivers to alleviate visual discomfort so as to achieve a balanced sense of driving safety and comfort. In this study, in order to overcome the drawbacks of existing tunnel lighting control modes that disregard the color temperature of natural light characteristics and collaborative influence of color temperature and luminance of natural light on tunnel lighting quality, one artificial neural network (ANN) model is designed and trained to simulate one physical lighting control system that takes into consideration color temperature and luminance simultaneously. In this model, multiple parameters of discrete and continuous types of input layer and output layer are synergistically analyzed. The model was also trained with quantities of field data from one tunnel in service and includes one hidden layer with 10 neurons. The simulation results showed that this model obtains a high degree of fitness with inside luminance and 100% recognition rate with inside color temperature in the threshold zone, which conforms to the regulation strategy of actual lighting control systems with high confidence. The proposed model will greatly enhance the reliability and sustainability of the lighting system during its normal operation, which can also support other lighting scenarios due to its flexibility and scalability with multiple-input and multiple-output (MIMO) capabilities.

A solar optical reflection lighting system for threshold zone of short tunnels: Theory and practice

This study develops a novel solar optical reflection (SOR) lighting system for threshold zone of short tunnels. In the system, the solar collector consists of a Fresnel lens and a dual axis sensor-date-time combined solar tracker, then the collected sunlight is reflected by a parabolic reflector and projected into the tunnel by air. In addition, a sunlight ray-tracing simulation was performed in TRACEPRO to evaluate the road surface illuminance distribution and illumination efficiency where the impacts of relative positions of system and projected light spot were investigated. Finally, the effectiveness and cost-benefit of the SOR lighting system were analyzed in the real tunnel application. The result shows that for an individual SOR lighting system, the illumination efficiency is relatively high, almost remaining the level of 70% theoretically. Upward projection of light spot leads to greater uniformity of illuminance distribution on the road surface, while it has lower average illuminance than downward projection. For array of multiple SOR lighting systems, downward projection outperforms upward projection with identical number of SOR lighting systems. In the real tunnel application, when the required illuminance and uniformity for threshold zone is met, the energy-saving of SOR lighting systems makes the tunnel lighting more sustainable compared with photoelectric tunnel lighting.

Sensing performances of hybrid steel wires and fibers reinforced ultra-high performance concrete for in-situ monitoring of infrastructures

Steel wires (SWs) with microscale diameter and high aspect ratio can overlap each other to form the stable conductive network at a low content, thus they are the promising conductive fillers to enhance the poor conductivity and sensing capacity of ultra-high performance concrete (UHPC) containing steel fibers (SFs) for in-situ monitoring of infrastructures. In this paper, the electrical conductivity and sensing performances to flexural loading of hybrid SWs and SFs reinforced UHPC are investigated, meanwhile, the conductive and sensing mechanisms are revealed by the analysis on microstructure, equivalent circuit and cracking behavior of composites. The test results indicated that 0.4 vol% SWs are in the percolation threshold zone, and the hybrid SWs and SFs have a positive synergistic effect on the conductivity of UHPC. The optimum electrical resistivity of UHPC with SFs can be reduced from 12900 Ω cm to 1310 Ω cm due to the addition of SWs. The hybrid SWs and SFs reinforced UHPC can effectively monitor the cracking initiation and development by measuring the fractional change in resistivities (FCR) under flexure, especially it performs more stable and accurate in monitoring the initial cracking and more sensitive in monitoring residual flexural loading and cracking development compared to mono SFs reinforced UHPC. This can be attributed to the inhibition effect of SWs on microcracks and the extensively conductive network formed by both SWs and SFs. UHPC with low content of hybrid SWs and SFs can already achieve self-sensing with high stability and sensibility in terms of in-situ monitoring crack initiation and propagation under flexural loading.

Comparative Study of Solar Optical Fibre and Electrical Light for Daylighting in Tunnel Threshold Zone

In recent years, there has been a considerable increase in traffic accidents in the tunnel region, especially around the threshold and exit zones, due to the inappropriate lighting system of these zones; leading to the loss of humans properties and lives. Therefore, lighting designers strive to improve the illumination issues of the threshold and exit zones which bring about “black hole” and “white hole” effects, respectively. Several solutions are proposed: solar optical fibre lighting system as a natural lighting system and LED, fluorescent lighting system as the artificial lighting system. This paper aims to compare the natural and artificial lighting system to show which lighting system is better and the best solution to solve these issues. The previous study in the Huashuyan tunnel in China, where natural light, solar optical fibre was used to illuminate the threshold zone, is simulated in LITSTAR4D software using a customized HCL-TN LED luminaire of LITPA Сompany. The simulation result is compared with the previous result obtained when the solar optical fibre is used. The simulation outcome gave a satisfying result with an average luminance of 91.15 cd/m2, which is higher than the average luminance required by the threshold zone. However, it is less when compared to the average luminance of 181.31 cd/m2 produced by the solar optical fibre system. The overall uniformity of 0.42 is above the requirements in the CIE88:2004 standards.

Tunnel Illumination: Algorithm to Determine Standard Values of Luminance in Tunnel Zones Using C Programming Language Approach

Tunnel illumination design involves complex mathematical computation, cumbersome, and tedious to perform when done by hand. This paper proposes an algorithm to compute luminance and luminous flux of the different zones of the tunnel by following the International Commission on Illumination (CIE88:2004) standard design guidelines using the C programming language. The luminance and the luminous flux values of all the zones were calculated and compared with the CIE standard. The energy consumption of each zone is equally found to control and reduce energy wastage and payment of unwanted bills. The threshold zone length Lth, average luminance in the first half Lav, and the last half of the threshold zone are 40 m, 400 cd/m2, and 240 cd/m2, respectively, while the average luminance of the transition and interior zones are, respectively, 95.87 cd/m2 and 5.86 cd/m2. The results obtained were satisfying. The computational results showed that the proposed Algorithm could be used to design an efficient tunnel illumination system with less energy waste.

Role of seed bank in aboveground vegetation regeneration signal ecosystem transition from arid grassland to shrubland with decreasing soil moisture

This study aimed to evaluate the role of seed bank during ecosystem transitions from arid grassland to shrubland. We explored the aboveground vegetation, seed bank and soil environmental factors at 29 sites along a moisture gradient that served as a space-for-time substitution in the Qaidam Basin on the Tibetan Plateau to test whether changes seed bank composition or changes in the ability of the seed bank to restore aboveground vegetation could lead to ecosystem transition. We found that the composition of the aboveground vegetation presented nonlinear changes with decreased soil moisture and showed an inflection point in the threshold zone on the spatial scale of ecosystem transition from arid grassland to shrubland; however, an inflection point was not observed for the seed bank. Surprisingly, we also found the similarity between the aboveground vegetation and seed bank decreased obviously when soil moisture crosses the critical threshold. Our results suggest that the transition from arid grassland to shrubland ecosystem is not caused by changes of the seed bank composition but by the inhibition of the seed bank's restorability to aboveground vegetation. Future work on changes in vegetation composition and species diversity with ecosystem transitions should consider the belowground seed bank.

Modifying self-sensing cement-based composites through multiscale composition

This paper aims to develop self-sensing cement-based composites with high sensitivity through building a multiphasic and multiscale conductive network formed by hybrid super-fine stainless steel wires (SSWs) and carbon nanotubes (CNTs)/nano-TiO2 particles (NTs). Experimental results show that 0.15 vol% SSWs are already in the percolation threshold zone, and incorporating CNTs/NTs has a synergistic effect of decreasing the electrical resistivity and increasing the strain sensitivity of cement-based composites under cyclic/monotonic compressive loading. The hybrid modification effect is closely related to the dosage and conductivity of nano-fillers. The sensing mechanisms mainly include the change of capacitance, tunneling resistance between fillers and intrinsic resistivity of fillers. For cement-based composites with 0.3 vol% SSWs, the electrical resistivity and self-sensing properties are primarily dominated by the SSW network, and are barely affected by the addition of CNTs. However, the strain sensitivity corresponding to the maximum absolute value of fractional change in electrical resistivity under monotonic loading is increased by 62.8% and reaches up to 140 as NTs are added, resulting from the semiconductor and nano-core properties of NTs to form a barrier between overlapping SSW conductive networks. It can therefore be concluded that tailoring different conductive networks by incorporating hybrid multiscale and multicharacteristic fillers is an effective method of developing self-sensing cement-based composites with high sensitivity.