Outdoor Field Test Research Articles

Enhanced Atmospheric Water Harvesting Performance by Three-Dimensional Carbon Fiber Felt Structure.

Freshwater shortages and the uneven distribution of water resources are critical issues for economic development and human life, and collecting water vapor in the air is one of the important ways to alleviate these issues. In recent years, adsorption-based atmospheric water harvesting (AWH) techniques have received much attention, and the core difficulty in establishing an efficient system is to develop a highly efficient functional material for AWH. In this work, an AWH material was prepared consisting of carbon fiber felt as a three-dimensional skeleton and loaded with poly(vinyl alcohol) immobilized LiCl and graphite, as a water capture and release functional material. A 24 h water capture-3 h water release test was carried out at room temperature, showing excellent water collection ability of 0.907 g·g-1 of water at 30% relative humidity (RH) and 2.429 g·g-1 of water at 80% RH. Using a 2 h capture-2 h release cycling test, the sample demonstrated a stable water capture-release performance. An outdoor field test was conducted, showing water collection efficiencies of up to 60%. We believe that the carbon fiber felt can provide good mechanical properties and achieve a high mass loading of the functional materials, and the composite material has a simple manufacturing process and realizes energy saving and sustainable water harvesting.

A spray-on environmentally friendly degradable mulch material and its high efficiency in controlling above-ground biomass of weeds in greenhouse experiments

AbstractThis study describes a novel spray-on mulch material as an alternative to currently used weed control methods. The mulch material is based on renewable raw materials, mainly rapeseed oil, starch and sodium alginate.Laboratory tests were conducted to obtain a mulch material with the best possible properties. Formulations with different ingredients were prepared and tested for their material properties. The formulations were investigated for potential shrinkage tendency and heat resistance as well as water resistance. Further tests such as resistance to mould infestation and aerobic degradability according to DIN EN ISO 17556 were carried out with the formulation that performed best in the previous tests. Mould resistance was enhanced by adding sodium benzoate. In the laboratory experiment, the CO2 decomposition rate was about 30% after seven weeks. With the favouritised variant, which was found step by step through the experiments, an outdoor field test was carried out to investigate the durability under natural conditions over the vegetation period. In the field, the mulch material maintained its function for six months. In the greenhouse, the effect of the mulch material on weeds was studied. It was found that the mulch material showed a high efficiency in controlling above-ground biomass of Elymus repens, Amaranthus retroflexus, and Setaria viridis. In addition, the biomass of the roots of Amaranthus retroflexus and Elymus repens was reduced. Further studies are on the way to elucidate field suitability and the weed suppressive effect under different environmental conditions.

Thermochromic Nanocellulose Films for Temperature-Adaptive Passive Cooling.

Energy efficiency in habitation spaces is a pivotal topic for maintaining energy sufficiency, cutting climate impact, and facilitating economic savings; thus, there is a critical need for solutions aimed at tackling this problem. One viable approach involves complementing active cooling methods with powerless or passive cooling ones. Moreover, considerable scope remains for the development of passive radiative cooling solutions based on sustainable materials. Cellulose, characterized by its abundance, renewability, and biodegradability, emerges as a promising material for this purpose due to its notable radiative cooling potential exploiting the mid-infrared (MIR) atmospheric transmission window (8-13 μm). In this work, we propose the utilization of thermochromic (TC) materials in conjunction with cellulose nanofibrils (CNF) to confer temperature-dependent adaptivity to hybrid CNF films. We employ a concept where high reflection, coupled with MIR emission in the heated state, facilitates cooling, while high visible light absorption in the cold state allows heating, thus enabling adaptive thermal regulation. CNF films were doped with black-to-leuco TC particles, and a thin silver layer was optionally applied to the films. The films exhibited a rapid transition (within 1 s) in their optical properties at ∼22 °C, becoming transparent above the transition temperature. Visible range transmittance of all samples ranged from 60 to 90%, with pronounced absorption in the 8-13 μm range. The cooling potential of the films was measured at 1-4 °C without any Ag layer and ∼10 °C with a Ag layer. In outdoor field testing, a peak cooling value of 12 °C was achieved during bright sunshine, which is comparable to a commercial solar film. A simulation model was also built based on the experimental results. The concept presented in this study extends beyond applications as standalone films but has applicability also in glass coatings. Overall, this work opens the door for a novel application opportunity for green cellulose-based materials.

On-site wind speed recovery from smartphone audio: Time domain deep learning approach, laboratory validation and outdoor field test

On-site wind speed information is paramount in various engineering domains. Conventional methods, reliant on expensive equipment and skilled operators, present challenges for practical uses. This study presents a novel time domain approach to recover wind speed from smartphone audio time series using deep learning. Leveraging the ubiquity of smartphones, the proposed approach offers a cost-effective and accessible alternative for wind speed measurement based on audio signals, allowing personnels to obtain on-site wind speed using smartphones. The model is built upon muti-layer architecture of one-dimensional convolutional neural network, and is trained and fine-tuned with high-fidelity wind tunnel laboratory data. The model’s performance is tested across different smartphone models and outdoor environments to assess its generalizability. The presented approach is generally effective, providing an overall accuracy with mean squared error of 0.2 to 0.9 (m/s)2. Although the model’s accuracy diminishes slightly in outdoor settings, it still shows favorable agreement with specialized wind gauges.

Analysis of the heat collection performance of a capillary solar heat collection wall structure

Solar thermal utilization in high-rise buildings is often constrained by the limited surface area of the rooftop. A novel façade-integrated capillary solar heat collection wall structure was proposed in this study, which involves embedding capillary tubes that circulate water within the cement mortar material, facilitating the integration of solar thermal collector and the exterior walls. To validate the feasibility of this new type of heat collection structure, experiments were conducted to investigate the impact of water flow rates on the heat collection performance of the proposed capillary solar heat collection wall structure under indoor solar simulator conditions, and outdoor field testing were conducted to assess its heat collection performance during winter, spring, and summer in Nanjing city. The experimental results revealed that, at water flow velocities of 0.05 m/s, 0.10 m/s, 0.15 m/s, and 0.20 m/s, the system's heat collection reached 4721 kJ, 4833 kJ, 4872 kJ, and 5326 kJ, respectively, showing a consistent increase with higher flow velocities in the capillary tube. The heat collection efficiency also increased gradually with flow velocity, but the rate of increase was relatively slow. The instantaneous heat collection efficiency decreased gradually as the experiment progressed, with a relatively small value of 47 % at a flow rate of 0.05 m/s. Data fitting revealed a linear relationship between the instantaneous collector efficiency and the normalized temperature difference at water flow velocities of 0.05 m/s and 0.1 m/s, and a quadratic exponential relationship at water flow velocities of 0.15 m/s and 0.2 m/s. During winter, spring, and summer in Nanjing city, the effective heat collection efficiency reached 45.8 %, 40.4 %, and 39.5 %, respectively, demonstrating that the capillary solar heat collection wall structure has significant potential in subtropical regions like Nanjing.

Self-rehydrating and highly entangled hydrogel for sustainable daytime passive cooling

Daytime passive cooling technology supported by coupling effects of daytime radiative cooling and evaporative cooling has drawn significant attention for alleviating the burdens of energy consumption and greenhouse gas emissions. Incorporating a hygroscopic agent allows the daytime radiative/evaporative cooler to replenish water itself at night, thus ensuring evaporative cooling during the daytime. However, the mechanism of the relationship between daytime passive cooling and nighttime rehydration is not fully understood. Besides, the design of circulating daytime radiative/evaporative coolers is segmented at present, and the poor mechanical properties of hydrogel restrict the practical application. Hence, a tough and elastic hydrogel with a highly entangled structure was prepared by dense polyacrylamide chains, exhibiting the 18-fold tensile stress and 9-fold compressive stress of the control group. Integrating zirconium dioxide (ZrO2) particles as a spectral regulator, the composite hydrogel possessed solar reflectance of 0.90 and mid-infrared emission of 0.88, realising daytime radiative cooling. After swelling in lithium bromide (LiBr) solution, the composite hydrogel achieved a cycle of daytime evaporative cooling and nighttime rehydration. Besides, the effects of LiBr concentrations on the evaporation and hygroscopicity of the composite hydrogel were investigated. Furthermore, two indoor experiments and one outdoor field test were performed, and the findings suggested that the design of strong hygroscopicity and effective evaporation was a contradiction, and it is crucial to narrow the gap between evaporation and rehydration instead of only pursuing the best cooling performance to achieve sustainable daytime passive cooling. Thus, it is hoped that this study could broaden the field of sustainable daytime passive cooling technologies.

Performance of Bio-based Products for Interior Insulation of Solid Masonry Walls

A recent Danish project has studied the possibilities of using bio-based materials for interior insulation of solid brick walls, without the use of a vapour barrier. The purpose was to give indications of the possibility to use hygroscopic insulation material in positions as interior insulation, where it is known to be potentially vulnerable to moisture accumulation. Three bio-based thermal insulation materials were investigated: loose-fill cellulose insulation (two variants) and hemp fibre insulation commercially available in Denmark. The hygrothermal performance of the three insulation materials for internal retrofitting purposes was investigated in a large-scale experiment comprising several solid masonry walls. The test walls were built in an outdoor test field north of Copenhagen, and exposed to a controlled indoor climate. The experiments were conducted over 1 year and 9 months where moisture measurements were done in several locations within the walls, including the interface between insulation and masonry, as well as in embedded wooden components such as a beam end and a wall plate. The paper illustrates the results from experiments with or without a hydrophobizing treatment on the exterior surface as causes of moisture content in potentially critical places in the walls. Finally, some results from mould growth determinations are reported. Generally, high levels of moisture content were found in the interior insulation, particularly for non-hydrophobized walls, but critical mould growth conditions were found only in the case of one of the tested materials.

Robust Pedestrian Dead Reckoning Integrating Magnetic Field Signals and Digital Terrestrial Multimedia Broadcasting Signals

Currently, many positioning technologies complementary to Global Navigation Satellite System (GNSS) are providing ubiquitous positioning services, especially the coupling positioning of Pedestrian Dead Reckoning (PDR) and other signals. Magnetic field signals are stable and ubiquitous, while Digital Terrestrial Multimedia Broadcasting (DTMB) signals have strong penetration and stable transmission over a large range. To improve the positioning performance of PDR, this paper proposes a robust PDR integrating magnetic field signals and DTMB signals. In our study, the Spiking Neural Network (SNN) is first used to learn the magnetic field signals of the environment, and then the learning model is used to detect the magnetic field landmarks. At the same time, the DTMB signals are collected by the self-developed signal receiver, and then the carrier phase ranging of the DTMB signals is realized. Finally, robust pedestrian positioning is achieved by integrating position information from magnetic field landmarks and ranging information from DTMB signals through Extended Kalman Filter (EKF). We have conducted indoor and outdoor field tests to verify the proposed method, and the outdoor field test results showed that the positioning error cumulative distribution of the proposed method reaches 2.84 m at a 68% probability level, while that of the PDR only reaches 8.77 m. The proposed method has been validated to be effective and has good positioning performance, providing an alternative solution for seamless indoor and outdoor positioning.

Derivation of External Exposure Characteristics of Industrial Radiography Based on Empirical Evidence

Background: This study aims to derive the characteristics of each work type for industrial radiography based on empirical evidence through expert advice and a survey of radiation workers of various types of industrial radiography.Materials and Methods: According to a Korean report, work types of industrial radiography are classified into indoor tests, underground pipe tests, tests in a shielded room (radiographic testing [RT] room test), outdoor field tests, and outdoor large structure tests. For each work type, exposure geometry and radiation sources were mainly identified through the expert advice and workers’ survey as reliable empirical evidence.Results and Discussion: The expert advice and survey results were consistent as the proportion of the work types were high in the order of RT room test, outdoor large structure test, underground pipe test, outdoor field test, and indoor test. The outdoor large structure test is the highest exposure risk work type in the industrial radiography. In most types of industrial radiography, radiation workers generally used 192Ir as the main source. In the results of the survey, the portion of sources was high in the order of 192Ir, X-ray generator, 60Co, and 75Se. As the exposure geometry, the antero-posterior geometry is dominant, and the rotational and isotropic geometry should be also considered with the work type.Conclusion: In this study, through expert advice and a survey, the external exposure characteristics for each work type of industrial radiography workers were derived. This information will be used in the reconstruction of organ dose for health effects assessment of Korean radiation workers.

Radiative Cooling Nanofabric for Personal Thermal Management.

A wearable textile that is engineered to reflect incoming sunlight and allow the transmission of mid-infrared radiation simultaneously would have a great impact on the human body's thermal regulation in an outdoor environment. However, developing such a textile is a tough challenge. Using nanoparticle-doped polymer (zinc oxide and polyethylene) materials and electrospinning technology, we have developed a nanofabric with the desired optical properties and good applicability. The nanofabric offers a cool fibrous structure with outstanding solar reflectivity (91%) and mid-infrared transmissivity (81%). In an outdoor field test under exposure of direct sunlight, the nanofabric was demonstrated to reduce the simulated skin temperature by 9 °C when compared to skin covered by a cotton textile. A heat-transfer model is also established to numerically assess the cooling performance of the nanofabric as a function of various climate factors, including solar intensity, ambient air temperature, atmospheric emission, wind speed, and parasitic heat loss rate. The results indicate that the nanofabric can completely release the human body from unwanted heat stress in most conditions, providing an additional cooling effect as well as demonstrating worldwide feasibility. Even in some extreme conditions, the nanofabric can also reduce the human body's cooling demand compared with traditional cotton textile, proving this material as a feasible solution for better thermoregulation of the human body. The facile fabrication of such textiles paves the way for the mass adoption of energy-free personal cooling technology in daily life, which meets the growing demand for healthcare, climate change, and sustainability.

Practical Nonlinear Model Predictive Controller Design for Trajectory Tracking of Unmanned Vehicles

The trajectory tracking issue of unmanned vehicles has attracted much attention recently, with the rapid development and implementation of sensing, communication, and computing technologies. This paper proposes a nonlinear model predictive controller (NMPC) for the trajectory tracking application of an unmanned vehicle (UV). First, a two-degree-of-freedom (2-DOF) kinematics model of this UV is used to derive the desirable controller with two control variables as forward velocity and yaw angle. Next, the one-step Euler method is employed to establish the nonlinear prediction model, then a nonlinear optimization objective function is formulated to minimize the tracking errors of forward velocity and yaw angle from a preset time-varying reference road. Finally, the effectiveness of the proposed NMPC scheme is assessed under two different driving scenarios via MATLAB simulations. The simulation results confirm that the proposed NMPC scheme reveals better control accuracy and computational efficiency than the standard MPC controller under two different prescribed roads. Moreover, an outdoor field test is conducted to verify the performance of the proposed NMPC scheme, and the results show that the proposed NMPC can be applied to the real vehicle and can improve the tracking accuracy and the driving stability of trajectory tracking.

Nanoplasmonic NO2 Sensor with a Sub-10 Parts per Billion Limit of Detection in Urban Air.

Urban air pollution is a critical health problem in cities all around the world. Therefore, spatially highly resolved real-time monitoring of airborne pollutants, in general, and of nitrogen dioxide, NO2, in particular, is of utmost importance. However, highly accurate but fixed and bulky measurement stations or satellites are used for this purpose to date. This defines a need for miniaturized NO2 sensor solutions with detection limits in the low parts per billion range to finally enable indicative air quality monitoring at low cost that facilitates detection of highly local emission peaks and enables the implementation of direct local actions like traffic control, to immediately reduce local emissions. To address this challenge, we present a nanoplasmonic NO2 sensor based on arrays of Au nanoparticles coated with a thin layer of polycrystalline WO3, which displays a spectral redshift in the localized surface plasmon resonance in response to NO2. Sensor performance is characterized under (i) idealized laboratory conditions, (ii) conditions simulating humid urban air, and (iii) an outdoor field test in a miniaturized device benchmarked against a commercial NO2 sensor approved according to European and American standards. The limit of detection of the plasmonic solution is below 10 ppb in all conditions. The observed plasmonic response is attributed to a combination of charge transfer between the WO3 layer and the plasmonic Au nanoparticles, WO3 layer volume expansion, and changes in WO3 permittivity. The obtained results highlight the viability of nanoplasmonic gas sensors, in general, and their potential for practical application in indicative urban air monitoring, in particular.

An integrated solar-driven system produces electricity with fresh water and crops in arid regions

Stable supplies of water, energy, and food are the most essential factors to universal achievements of the United Nation’s Sustainable Developments Goals (SDGs) by 2030. This work reports a self-sustained and solar-driven, integrated water-electricity-crop co-production system (WEC2P). The design of WEC2P is based on the atmospheric water adsorption-desorption cycle (1) to generate cooling power for photovoltaic (PV) cells to increase their electricity generation performance or (2) to sustainably produce fresh water from atmospheric water vapor to support crop growth. During the 3-month-long outdoor field test, the WEC2P successfully reduced the temperature of PV panels by up to 17°C and increased their electricity generation by up to 9.9% in the PV cooling mode. Meanwhile, it produced water to irrigate crops (i.e., water spinach) hosted in an integrated plant-growing unit in Saudi Arabia, with a crop surviving rate of 95%. Thereby, WEC2P may represent a meaningful contribution to the global water-energy-food nexus.

The performance and cognitive workload analysis of a multimodal speech and visual gesture (mSVG) UAV control interface

This paper conducts a comparison of the performance and cognitive workload between three UAV control interfaces on an nCA (navigation control autonomy) Tier 1-III flight navigation task. The first interface is the standard RC Joystick (RCJ) controller, the second interface is the multimodal speech and visual gesture (mSVG) interface, and the third interface is the modified version of the RCJ interface with altitude, attitude, and position (AAP) assist. The modified RCJ interface was achieved with the aid of the Keyboard (KBD). A model of the mSVG interface previously designed and tested was used in this comparison. An experiment study was designed to measure the completion time and navigation accuracy of participants using each of the three interfaces, on a developed path_v02 test flight path. Thirty-seven (37) participants volunteered. The NASA task load index (TLX) survey questionnaire was administered at the end of each interface experiment to access the participants experience and to estimate the interface cognitive workload. A commercial software, the RealFlight Drone Simulator (RFDS) was used to estimate the RCJ skill level of the participants. From the results of the experiment, it was shown that the flying hours, the number of months flying, and the RFDS Level 4 challenge performance was a good estimator for participants RCJ flying skill level. A two-way result was obtained in the comparison of the RCJ and mSVG interfaces. It was concluded that, although the mSVG was better than the standard RCJ interface, the AAP-assisted RCJ was found to be as effective as (in some cases better than) the mSVG interface. It was also shown, from the speech gesture ratio result, that the participants had a preference for gesture over speech when using the mSVG interface. Some further works such as an outdoor field test and a performance comparison at higher nCA levels were suggested.

Development and Challenges of Metal Halide Perovskite Solar Modules

Metal halide perovskites are considered as game changers for future solar cell technology due to their rapidly increasing device efficiencies and potential for manufacturing at low cost. In view of their promising commercial potential, increasing research efforts are now dedicated to the development of large‐area perovskite solar modules. Herein, the motivation for developing perovskite solar modules and the challenges to fabricate large‐area perovskite solar cells with high efficiency are discussed. The important thin‐film processing methods including solution‐based and vacuum‐based deposition technologies for scaling up the fabrication of perovskites are reviewed. In addition, other key challenges that need to be overcome to bring perovskite solar modules into photovoltaic (PV) markets are also discussed, including module stability, potential lead leakage issue, and outdoor field testing of the perovskite modules. Finally, opinions on the future development of perovskite PV modules are shared.

Designing a\xa0next generation solar crystallizer for real seawater brine treatment with zero liquid discharge

Proper disposal of industrial brine has been a critical environmental challenge. Zero liquid discharge (ZLD) brine treatment holds great promise to the brine disposal, but its application is limited by the intensive energy consumption of its crystallization process. Here we propose a new strategy that employs an advanced solar crystallizer coupled with a salt crystallization inhibitor to eliminate highly concentrated waste brine. The rationally designed solar crystallizer exhibited a high water evaporation rate of 2.42 kg m−2 h−1 under one sun illumination when treating real concentrated seawater reverse osmosis (SWRO) brine (21.6 wt%). The solar crystallizer array showed an even higher water evaporation rate of 48.0 kg m−2 per day in the outdoor field test, suggesting a great potential for practical application. The solar crystallizer design and the salt crystallization inhibition strategy proposed and confirmed in this work provide a low-cost and sustainable solution for industrial brine disposal with ZLD.

Evaluation and Analysis of Selective Deployment of Power Optimizers for Residential PV Systems

Partial shading is widely considered to be a limiting factor in the performance of photovoltaic (PV) systems applied in urban environments. Modern system architectures, combined with per module deployment of power electronics, have been used to improve performance, especially at heterogeneous irradiance conditions, but they come with a high investment cost. In this paper, another approach is used to evaluate the selective deployment of power optimizers (SDPO), which can operate with a variety of string inverters and can be retrofitted in PV systems suffering from high shading losses. A combination of modelling and outdoor field testing showed the benefits and drawbacks of SDPOs in a variety of shading scenarios. Results suggest that there is an energy yield increase of 1–2% on an annual basis compared to that of a reference system. The exact level of increase depends on the shading patterns and combination scenarios used in this paper.

Interplay between temperature and bandgap energies on the outdoor performance of perovskite/silicon tandem solar cells

Perovskite/silicon tandem solar cells promise power conversion efficiencies beyond the Shockley–Queisser limit of single-junction devices; however, their actual outdoor performance is yet to be investigated. Here we fabricate 25% efficient two-terminal monolithic perovskite/silicon tandem solar cells and test them outdoors in a hot and sunny climate. We find that the temperature dependence of both the silicon and perovskite bandgaps—which follow opposing trends—shifts the devices away from current matching for two-terminal tandems that are optimized at standard test conditions. Consequently, we argue that the optimal perovskite bandgap energy at standard test conditions is <1.68 eV for field performance at operational temperatures greater than 55 °C, which is lower compared with earlier findings. This implies that bromide-lean perovskites with narrower bandgaps at standard test conditions—and therefore better phase stability—hold great promise for the commercialization of perovskite/silicon tandem solar cells. Outdoor field testing is crucial to understand how solar cells behave under operational conditions. Here, Aydin et al. show that a lower perovskite bandgap than that calculated at laboratory standard test conditions enhances the performance of perovskite/silicon tandem cells in the field.

Design and test of a gravity-assisted vacuum seed-meter for maize

In order to improve the operating performance of vacuum seed-meter, a gravity-assisted seed filling method is provided. The radial components of seeds gravitational force and upper seeds pressure of seeds to be filled are consistent with the direction of drag force. Components of the seeds pressure and the gravity of seeds to be filled play an auxiliary role in seed filling. A gravity-assisted seed filling vacuum seed mater is designed, and the gravity-assisted seed filling mechanism and working principle are described. Operating performance of the designed seed-meter was evaluated by a two-factor indoor laboratory test and a single factor outdoor field test. Qualified index, double index, and missing index were estimated. Optimal working parameters combination of laboratory tests for operating velocity and air pressure were 6km/h and -4.5kPa respectively. Maximum field operating velocity was 9.48km/h. Optimum field operating velocity was 7.68km/h and qualified index, double index, missing index were 92.43%, 0.67%, and 6.9% respectively at this velocity.

The Outdoor Field Test and Energy Yield Model of the Four-Terminal on Si Tandem PV Module

The outdoor field test of the 4-terminal on Si tandem photovoltaic module (specifically, InGaP/GaAs on Si) was investigated and a performance model, considering spectrum change affected by fluctuation of atmospheric parameters, was developed and validated. The 4-terminal on Si tandem photovoltaic module had about 40% advantage in seasonal performance loss compared with standard InGaP/GaAs/InGaAs 2-terminal tandem photovoltaic module. This advantage increases (subarctic zone &lt; temperate zone &lt; subtropical zone). The developed and validated model used an all-climate spectrum model and considered fluctuation of atmospheric parameters. It can be applied every type of on-Si tandem solar cells.