Outdoor Experiments Research Articles

Visible transparency modulated cooling windows using pseudorandom dielectric multilayers

Abstract The increasing global temperatures have escalated the demand for indoor cooling, thus requiring energy-saving solutions. Traditional approaches often integrate metal layers in cooling windows to block near-infrared (NIR) sunlight, which, albeit effective, lack the broad modulation of visible transmission and lead to heat accumulation due to sunlight absorption. Here, we address these limitations by developing cooling windows using ZnS/MgF2 multilayers, optimized through a binary optimization-based active learning process. We demonstrated that these multilayers, with a total thickness below 1 µm, effectively reduced indoor temperatures by blocking NIR sunlight while achieving desired visible transmittance. The designed multilayers exhibited visible transmittance ranging from 0.41 to 0.89 while retaining decent NIR reflectance between 0.37 and 0.52. These spectral characteristics remained consistent up to incident angles of >60°, ensuring their practical applicability for vertically oriented windows. Outdoor experiments showed substantial temperature reductions of up to 8.8 °C on floors compared to uncoated glass windows. The active learning-based multilayers exhibited superior performance compared to analytical ZnS/MgF2 distributed Bragg reflectors with equivalent thicknesses by improving NIR reflectance and modulating visible transmittance. In addition, multilayers with a greater number of bits extensively tuned transmission color, enabling customization for aesthetic purposes. These findings suggest that all-dielectric multilayers can provide a scalable, cost-effective alternative for reducing energy consumption in buildings and vehicles with large glass surfaces, supporting efforts to mitigate climate change through enhanced energy efficiency.

Impact of Snow on Underground Smoldering Wildfire in Arctic-Boreal Peatlands.

Overwintering peat fires are re-emerging in snow-covered Arctic-boreal regions, releasing unprecedented levels of carbon into the atmosphere and exacerbating climate change. Despite the critical role of fire-snow interactions in these processes, our understanding of them remains limited. Herein, we conducted small-scale outdoor experiments (20 × 20 × 20 cm3) at subzero temperatures (-5 ± 5 °C) to investigate the impact of natural snowfall and accumulated snow layers (up to 20 cm thick) on shallow smoldering peat fires. We found that even heavy natural snowfalls (a maximum water equivalent snowfall intensity of 1.1 mm/h or a 24 h accumulated snowfall water equivalent precipitation of 7.9 mm) cannot suppress a shallow smoldering peat fire. A thick snow cover on the peat surface can extract heat from the burning front underneath, and the minimum thickness of the snow layer to extinguish the peat fire was found to be 9 ± 1 cm at subzero temperatures, agreeing well with the theoretical analysis. Furthermore, larger-scale field demonstrations (1.5 × 1.5 m2) were conducted to validate the small-scale experimental phenomena. This work helps us to understand the interactions between fire and snow and reveals the persistence of smoldering wildfires under cold environments.

Targetless Radar–Camera Extrinsic Parameter Calibration Using Track-to-Track Association

One of the challenges in calibrating millimeter-wave radar and camera lies in the sparse semantic information of the radar point cloud, making it hard to extract environment features corresponding to the images. To overcome this problem, we propose a track association algorithm for heterogeneous sensors, to achieve targetless calibration between the radar and camera. Our algorithm extracts corresponding points from millimeter-wave radar and image coordinate systems by considering the association of tracks from different sensors, without any explicit target or prior for the extrinsic parameter. Then, perspective-n-point (PnP) and nonlinear optimization algorithms are applied to obtain the extrinsic parameter. In an outdoor experiment, our algorithm achieved a track association accuracy of 96.43% and an average reprojection error of 2.6649 pixels. On the CARRADA dataset, our calibration method yielded a reprojection error of 3.1613 pixels, an average rotation error of 0.8141°, and an average translation error of 0.0754 m. Furthermore, robustness tests demonstrated the effectiveness of our calibration algorithm in the presence of noise.

Redesign of a Towing Mobile Robot Control Architecture and Implementation of Outdoor Experiments Using the Transverse Function Approach

This article discusses the redesign of a towing mobile robot to obtain a modern system for implementing mobile robot control research. Controller architecture issues are presented, and a selected control algorithm is considered in detail. The reconstruction of the robot is also intended to ensure that the current standards for the electronic architecture controlling the robot are met and that this architecture can be easily developed to include components related to the safety of the robot’s operation. The discussion of the control architecture is divided into a description of the high-level controller responsible for the position stabilization algorithm and a description of the low-level controller responsible for the drive motor control and robot safety. The high-level control algorithm is responsible for a trajectory tracking task realized with use of a transverse function approach algorithm. A time elastic band algorithm was also used to generate a reference trajectory, allowing the robot to be guided through waypoints. The low-level controller is comprehensively described with details on the industrial controller architecture used, the communication between the controller modules, and the interaction of these modules with the on-board computer. The redesign of the towing mobile robot was summarized by the implementation of outdoor experiments where the task of driving through reference points was completed.

3D hydrogel-based salt resistant self-floating solar-driven interfacial evaporator with efficient water-lifting capacity for desalination

Solar desalination has been extensively researched as a promising way to address freshwater shortages. However, developing a salt resistant solar evaporator that can be easily extended and manufactured is still a challenge in practical applications. In this work, a 3D hydrogel-based salt resistant self-floating solar-driven interfacial evaporator with efficient water-lifting capacity was proposed using the prepared hydrogel with carbon black (CB) nanoparticles and extruded polystyrene (XPS) board as raw materials. The experimental results implied that the developed evaporator had the highest evaporation rate and evaporation efficiency at 0.05 g CB loading, which were 1.70 kg m-2h−1 and 92.8 % at a light intensity of 1 kW/m−2(−|-). Moreover, the evaporator also displayed prominent salt resistance in the evaporation of brine with high salinity and outstanding stability after 10 cycles. Significantly, the outdoor experiment demonstrated that 1 m2 evaporator can generate 5923.5 g freshwater per day, which was enough to meet the daily requirement of two adults for drinking water. In addition, the physical fields of the hydrogel with CB nanoparticles of the evaporator at evaporation equilibrium were simulated to analyze its long-term and high-performance operation capability. All in all, the 3D hydrogel-based salt resistant self-floating solar-driven interfacial evaporator with efficient water-lifting capacity presented an enormous application prospect in the field of solar desalination.

Free-form surface-based polar-axis rotational direct solar radiation spectrum measurements

Accurate measurements of direct solar radiation spectra are crucial for atmospheric science, climatology, agriculture, and solar energy. Existing systems depend on costly dual-axis tracking devices, leading to high maintenance and error rates. This study presents a free-form surface-based polar-axis rotating solar direct radiation spectrometer, enabling year-round measurements across all latitudes without mobile tracking. The system operates in the 380–780 nm range with a spectral resolution better than 2 nm. Simulation results demonstrate spectral curve area errors between 0.68% and 1.22%, and outdoor experiments in Changchun, China, confirm the accuracy of measurements against the AM1.5 G standard.

Investigation of ventilation performance in the multi-story building with various envelope features: Scaled outdoor experiments

Investigation of ventilation performance in the multi-story building with various envelope features: Scaled outdoor experiments

Effect of Trace Rare Earth Elements (Ce) on the Corrosion Resistance of High-Strength Weathering Bridge Steels

In this study, Q370qENH high-strength weathering bridge steel was used as the base material. The corrosion experiment in a marine atmosphere was simulated by the salt spray test, and the outdoor atmospheric exposure corrosion experiment and electrochemical method test were carried out. The corrosion behavior of Q370qENH high-strength weathering bridge steel in a marine atmosphere was studied using electron probe microanalysis (EPMA), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and other surface testing techniques. The results show that the corrosion rate of the steel gradually decreases with the increase in the content of trace rare earth elements. Ce played a role in the modification of inclusions so that MnS was modified into rare earth composite inclusions, which slowed down the occurrence of corrosion. The enrichment of Cu alloy elements in the inner rust layer of the rare earth experimental steel improves the compactness of the rust layer, and the thickness of the inner rust layer is increased by 42%, which enhances the stability of the rust layer. With the increase in cerium, the protection coefficient α/γ* of the rust layer of experimental steel increases, indicating that the corrosion resistance of the material is improved. In addition, the electrochemical results show that the addition of rare earth elements in Q370qENH steel will lead to a positive shift in the electrochemical self-corrosion potential, a larger impedance radius of the steel rust layer, and a stronger protective effect. Due to the addition of trace cerium, the seawater corrosion resistance of the test steel is improved.

Synergistic activation of peroxydisulfate by photothermal and FeS2-loaded air-laid cloth in a shallow continuous flow reactor.

Synergistic activation of persulfate by photothermal and solid catalysts is an effective method for degrading organic pollutants. However, the batch reaction mode not only fails to fully utilize photothermal, but also makes it hard to separate the solid catalysts from the reaction solution. In this work, a shallow continuous flow way of effluent was set up for synergistic activation of peroxydisulfate (PDS) by photothermal and FeS2-loaded air-laid cloth (FeS2-ALC). The degradation efficiency of carbamazepine (CBZ) was significantly enhanced with a pseudo-first-order kinetic constant of 0.0359 min-1, which is 180, 40 and 10 times higher than that of the photothermal/ALC, photothermal/FeS2-ALC and photothermal/PDS processes, respectively. The enhanced efficiency was partly due to the absorption of sunlight by FeS2-ALC to heat up the reaction solution which in turn can use photothermal to activate PDS, and partly due to the activation of the PDS by Fe2+ from FeS2-ALC and the promotion of Fe3+/Fe2+ cycling via S2-. Parameters such as reaction conditions, hydraulic conditions and water quality parameters affecting degradation efficiency were investigated. A possible degradation pathway was proposed and the toxicities of byproducts were tested. Finally, cycling experiments and outdoor experiments demonstrated that the photothermal/FeS2-ALC/PDS process has potential for practical wastewater treatment.

Robust formation control of multiple aerial robotic vehicles using near neighbor cyclic deviation with time-varying disturbances.

Cooperative formation flight of multiple aerial robotic vehicles (ARVs) is extensively adopted in emergency rescue and collaborative transport. But the time-varying complex disturbances are inevitable in the cooperative formation flight of multiple ARVs, which can affect the formation stability of multi-ARV systems. This paper investigates the robust formation control problems for multiple ARVs with time-varying disturbances. A novel high-order sliding mode control (HOSMC)-based near neighbor cyclic deviation synchronization control (NNCDSC) scheme for multi-ARV systems is proposed, which can improve the formation control precision and enhance the robustness against time-varying complex disturbances. Firstly, the formation control problem is transformed into the synchronization control problem of multi-ARV systems; a novel NNCDSC strategy is proposed, that can decrease the complexity of the formation control system. Secondly, to better cope with time-varying complex disturbances and improve the formation control accuracy of multi-ARV systems, the HOSMC-based NNCDSC scheme for multi-ARV systems is designed by combining NNCDSC and HOSMC. The finite time stability of the formation control system can be guaranteed by Lyapunov stability theorem, and the desired time-varying or time-invariant formation of multi-ARV systems can also be achieved. Finally, the validity of the theoretical results is verified by several simulation examples and an outdoor experiment.

Impact of simulated global warming on nutrient release from decomposing fish carcasses

ABSTRACT Fish biomass often represents a locus where nitrogen and phosphorus are concentrated in aquatic environments. The postmortem fate of these essential biogenic elements, sequestered by fish, and the ratios at which these become available to other organisms, can be crucial in determining ecosystem functioning and productivity. Several environmental factors affect/drive the process of carcass decay, with water temperature playing a particularly important regulatory role. Therefore, we anticipate that escalating global warming will accelerate fish carcass decomposition and, consequently, alter nutrient recycling rates in freshwater ecosystems. To investigate how elevated water temperatures impact fish decay rates and the associated internal nutrient loading, an outdoor mesocosm experiment was conducted to simulate the effects of a massive fish kill under varying temperature conditions (ambient temperature, and +3 °C warmer). Our results indicate that fish (common bleak, Alburnus alburnus) carcasses lost ∼90% of their original body mass after 6 weeks and functioned as a typical source of nitrogen and a partial sink of their original phosphorus content. Elevated temperature significantly boosted carcass decay and, together with decomposition-derived nutrients, affected both planktonic and benthic algae. A similar effect on the zooplankton community was not observed.

Biomass allocation and growth of young Black spruce (Picea mariana (Mill.) B.S.P.) trees

Accurately predicting biomass allocation to below- versus above-ground tree parts is crucial in estimating carbon stocks in forest ecosystems. A nine-year outdoor experiment was conducted to analyze the variations in C allocation in below- and above-ground parts in black spruce trees growing at the edge or at the center of a raised garden bed. Dry biomass, length and radial growth of stems, branches and roots were measured as well as the annual above-ground growth for the five most recent years prior to harvesting. We found that more than 90% of dry biomass was allocated to the above-ground tree parts whereas less than 10% was allocated to the root system. Strong correlations were found between the different tree parts regardless of the tree’s position in the delimited growth area. Annual growth variables declined from 2018 to 2022, likely due to increased competition for resources. Basal area and stem height were good predictors for the production of stem dry biomass (88%), and to a lesser extent for the total tree biomass (65%). The dry biomass of the woody root and the root surface close to the stem were well correlated to the above-ground tree parts (varying between 45% to 95%). Thus, the strong link between the root system and the above tree parts is confirmed.

Flood-driven survival and growth of dominant C4 grasses helps set their distributions along tallgrass prairie moisture gradients.

Five C4 grasses (Bouteloua curtipendula, Schizachyrium scoparium, Andropogon gerardii, Sorghastrum nutans, Spartina pectinata) dominate different portions of a moisture gradient from dry to wet tallgrass prairies in the Upper Midwest of the United States. We hypothesized that their distributions may partly reflect differences in flooding tolerance and context-specific growth relative to each other. We tested these ideas with greenhouse flooding and drought experiments, outdoor mesocosm experiments, and a natural experiment involving a month-long flood in two wet-mesic prairies. Bouteloua promptly succumbed to inundation, so flooding intolerance likely excludes it from wet and wet-mesic prairies. Competition is likely to exclude short-statured Bouteloua from productive mesic sites. Schizachyrium is excluded from wet prairies by low flooding tolerance, demonstrated by all experiments. Sorghastrum had low flooding tolerance in both greenhouse and natural experiments, suggesting that physiological intolerance excludes it from wet prairies. Spartina had by far the greatest growth under the wettest mesocosm conditions; this and comparisons of species growth in monocultures vs. mixtures suggests that competition helps it dominate wet prairies. Indeed, quadrat presence of Spartina increased by 57% two years after flooding of two prairies, while that of upland grasses declined by 44%. The high flooding tolerance, lack of significant differences from other species in drought tolerance, and tall stature of Andropogon suggest that broad physiological tolerance combined with competitive ability allows it to thrive across the prairie moisture gradient. Flooding helps shape the distributions of dominant prairie grasses, and its effects may become more important as extreme rain events continue to increase.

The effects of a microplastic mixture on wood frogs (Rana sylvatica) across multiple life stages in an outdoor mesocosm experiment

Abstract Microplastics have been found across the globe in the habitats of many amphibians. To investigate how exposure to microplastics affects hatching success, survival, growth, and development of wood frogs (Rana sylvatica), as well as how these animals may act as vectors for microplastics, a 96-day outdoor mesocosm experiment was conducted at the Queen’s University Biological Station (Ontario, Canada). Wood frogs were allocated to a negative control group or exposed to an additive-containing microplastic mixture (equal parts polypropylene, polystyrene, and polyethylene terephthalate) at nominal water concentrations of 0.069 g/L or 0.691 g/L. Whereas hatchling survival, hatching success, and hatchling size did not differ among experimental groups, exposure to microplastics caused increased larval growth at both microplastic concentrations and delayed larval development at the highest concentration. However, there was little evidence that survival, body size, or development of metamorphs were affected by exposure to microplastics. We found microplastics in the gastrointestinal tract and on the skin of wood frogs and also inside the liver and leg muscle. In addition, the presence of frogs enhanced the flux of positively buoyant microplastics between the aquatic and terrestrial environment. This study provides new insights into how microplastic pollution affects the growth and development of wood frogs and suggests that amphibians with a biphasic life cycle may act as biovectors of plastics across water–land interfaces.

Reversing LeTID in PV power plants: a feasibility study

Light and elevated Temperature Induced Degradation (LeTID) is likely causing strong yield losses in a significant number of photovoltaic (PV) power plants which were commissioned in the late 2010s. In this work, a procedure for an in-field recovery using overnight current injection to trigger temporary recovery of LeTID is presented. The general feasibility of such a procedure is first demonstrated by climatic chamber experiments on strongly degraded mc-Si PERC PV modules. Within the screened test conditions, a temporary recovery procedure with high currents and low module temperatures is most promising for an economic application in PV power plants. An outdoor experiment with current injection during nights and MPP tracking during days confirmed the possibility to recover LeTID in PV power plants. By injecting a pulsed current, the heating of the modules caused by the current injection was strongly reduced compared to the heating at constant current injection. Recommendations for the application of a procedure in PV power plants are given based on the required energy expenditure and cost.

Experimental investigation to improve the performance of the PV module using graphene hydrophobic nano coating coupled with top water cooling

This research aims to enhance the efficiency of polycrystalline silicon solar photovoltaic panels by addressing the dual challenges of dust accumulation and temperature variations. The study investigates the effects of applying a hydrophobic graphene nano-coating on the top surface of the panels to prevent dust buildup, coupled with a top water-cooling system to regulate panel temperature. Outdoor experiments were conducted in Coimbatore, India, from 8:00 am to 4:00 pm under sunny conditions for 40 days. A total of eight identical photovoltaic panels were tested with various configurations, and performance parameters such as glass temperature, tedlar temperature, output power, solar radiation, ambient temperature, and wind speed were recorded. Experimental results show that the graphene nano-coating reduces panel temperature by 9.36% compared to the dusty panel and 3.8% compared to the uncoated, manually cleaned panel by day 40. The nano-coating alone increased power output and efficiency by 4.16% and 3.3%, respectively, compared to the uncoated, no-cooling panel. Additionally, the nano-coated, top water-cooled panels showed improvements of 16.87% in output power and 13.22% in efficiency compared to the uncoated, no-cooling panel, and 3.11% in power and 2.82% in efficiency compared to the uncoated, water-cooled panels. These results demonstrate that the combined application of graphene nano-coating and water cooling effectively enhances the performance and longevity of photovoltaic modules by reducing dust accumulation and regulating temperature.

Evaluating long-term thermal and chemical stability and leaching potential of low-temperature phase change materials in concrete slabs exposed to outdoor environmental conditions

This study examined the potential of using phase change material (PCM)-integrated concrete slabs for long-term thermal-responsive applications in an outdoor environment condition. The objectives were to: (i) evaluate long-term thermal response, snow melting and freeze–thaw reduction efficiency of PCM integrated concrete slabs, (ii) characterize the chemical stability of PCM in cement matrix, and (ii) assess the possibility of PCM leaching into the cement matrix and subgrade soil of the slabs. The experimental program included: (i) outdoor experimentation using large-scale field concrete slabs, (ii) guarded calorimetric (LGCC) tests of cut-bar concrete specimens, (iii) Fourier transform infrared (FTIR) spectroscopic characterization of PCM in mortar and subgrade soil specimens, and (iv) low-temperature differential scanning calorimetric (LT-DSC) tests to assess and quantify the amount of PCM contamination in subgrade soil. Results presented varying degrees of effectiveness after three years of environmental exposure: Micro-encapsulated PCM (MPCM) concrete exhibited considerable success (i.e., ~ 50%) in snow melting while PCM infused in lightweight aggregates (PCM-LWA) concrete failed to provide substantial snow-melting; moreover, both PCM-LWA and MPCM slabs showed diminished resistance to freeze–thaw (F-T) cycles compared to the first-year winter cycle data. Factors contributing to efficiency loss are found to be shell degradation of microcapsules, potential leaching of PCM into subgrade soil (i.e., between 0.2 to 0.3% wt. concentration), and effects of warm temperatures influencing the degree of evaporation, as evidenced with LGCC, FTIR and LT-DSC results. Strategies to enhance efficiency and stability include improved encapsulation techniques, and vascularization methods.

A Fundamental Study on an SAP Mixed Asphalt Mixture for Reducing the Urban Heat Island Effect

As the average temperature in summer rises and heat waves occur more frequently, the urban heat island (UHI) phenomenon is becoming a social problem. Asphalt road pavement stores heat during the day, raising the surface temperature, and releases the stored heat at night, thereby aggravating the UHI phenomenon. Government authorities often spray water to lower the temperature of road pavement for the safety and convenience of citizens. However, the effect is immediate and does not last long. Therefore, in order to reduce the urban heat island phenomenon by spraying water, the recovery time of the surface temperature must be delayed. In this study, Super Absorbent Polymer (SAP), a highly absorbent polymer that absorbs 100 to 500 times its weight in water, was applied to asphalt road pavement. SAP is commonly used in diapers, feminine hygiene products, soil moisturizers, and concrete, and its scope is gradually expanding. The purpose of this study is to reduce the urban heat island phenomenon by mixing the SAP into asphalt and to increase the latent heat flux by evaporating the water absorbed by the SAP, thereby delaying the recovery time of the surface temperature of the road pavement. In this study, the performance of asphalt mixtures mixed with the SAP and the thermal characteristics according to the mixing amount were analyzed. In this study, the physical properties and temperature reduction performance of the asphalt mixture according to the SAP type and content were studied. The results of indoor and outdoor experiments on asphalt mixtures using the SAP showed that they satisfied the mechanical performance criteria as asphalt pavement materials and that the temperature recovery delay effect was improved.

Evaluation of a micro-particle-enhanced phase-change material integrated heat pipe evacuated tube solar collector system using lanthanum oxide/water nanofluid

ABSTRACT In this study, the thermal performance of a microparticle-enhanced form-stable phase change material (PCM) integrated heat pipe evacuated tube solar collector (ETSC) system is evaluated through outdoor experimentation. The study examines the thermal performance of PCM-enhanced ETSC using acetamide with varying percentages of expanded graphite (EG) at 10, 15, and 20 wt% and aluminum microparticles at 1, 2, and 5 wt%, focusing on the use of EG at different concentrations and microparticles. The microparticle-enhanced form-stable PCM is integrated into the tube only. The system was tested under open environmental conditions, comparing outcomes with a normal ETSC system, considering water outlet temperature, charging-discharging behaviors, collector efficiency, and energy analysis. The study revealed that the micro-particle enhanced PCM integrated heat pipe ETSC system significantly improved thermal performance, energy storage and release capabilities, and efficiency in generating heat at lower solar irradiance, compared to conventional ETC systems. The maximum collector efficiency of 47.4% is achieved when utilizing acetamide with 10% EG and 2% Al, which is 10.9% more than conventional ETSC. The study explores the use of lanthanum oxide/water nanofluid in solar collectors, revealing that increasing nanoparticle concentrations enhances water outlet temperature, heat gain, and solar thermal collector efficiency up to 64.14%.

FlexSARCloak: A Flexible SAR Cloak Driven by Task-Oriented Learning.

Invisibility─the remarkable ability to render objects imperceptible─has long been a persistent dream of humankind. However, traditional cloaking materials are typically rigid and inflexible, limiting their adaptability to various shapes and requirements. Even when flexibility is achieved, uncontrollable scattering in complex electromagnetic environments continues to pose significant challenges in the design of flexible cloaks. In this paper, we present a task-oriented learning (TOL)-based metasurface design approach, successfully realizing a broadband, polarization-independent, flexible SAR cloak (FlexSARCloak). Experimental results reveal that the cloak achieves over 90% absorption efficiency across the 9-25 GHz frequency range for incidence angles ranging from 0 to 60°. Outdoor experiments further confirm that the FlexSARCloak achieves near-perfect invisibility under UAV-mounted SAR. Furthermore, a comprehensive series of environmental tests, including exposure to extreme temperatures, variable humidity, and sandstorm conditions, was conducted to simulate natural or extreme conditions, which successfully validated the stability of the electromagnetic performance. The proposed FlexSARCloak presents considerable potential for applications in electromagnetic protection and related domains. Moreover, the introduction of the TOL algorithm is expected to significantly accelerate the design and optimization of metasurfaces, paving the way for the physical realization of multifunctional metasurfaces.