Real Outdoor Environments Research Articles

EMF-PAL: Enhanced Multi-sensor Fusion Algorithm for High-Precision Perception and Localization in Challenging Environments

Abstract This study proposes an enhanced multi-sensor fusion perception and localization algorithm named EMF-PAL, which leverages the strengths of three distinct sensor types to achieve high-precision localization. The algorithm employs a lightweight object detection network to extract semantic information from the environment, which is combined with feature points obtained through parallel bidirectional optical flow tracking. A dual-strategy approach is introduced to identify reliable static feature points, enabling accurate pose estimation. Sensor data is dynamically updated using factor graph optimization to ensure accurate and continuous real-time localization. In the feature preprocessing module, the lightweight object detection algorithm is integrated with Shi-Tomasi corner detection to provide prior information for subsequent object recognition and filtering. Additionally, the high-precision inertial measurement unit (IMU) supplies translation and rotation data, enabling short-term, high-accuracy positioning and motion compensation, effectively reducing misclassification during rapid movements. The Global Navigation Satellite System- Real-time kinematic (GNSS-RTK) provides all-weather, drift-free global localization information without the need for additional transformations, further enhancing the factor graph optimization for position updates and supplying auxiliary data to the IMU. EMF-PAL maximizes the advantages of multiple sensors, making it well-suited for complex environments. Extensive comprehensive experimental validation using real outdoor environment sequences under different environmental conditions is conducted to demonstrate the real-time accuracy of EMF-PAL and its ability to cope with complex environments. The experimental results demonstrate that the proposed method enhances localization accuracy by up to 50.3% in chanllenging outdoor environments compared to state-of-the-art(SOTA) algorithms utilizing three-sensor fusion, effectively fulfilling the localization and perception requirements of real-world applications.

Effect of rear pyramid structures on industrial bifacial PERCs under omnidirectional incidence

The bifacial passivated emitter and rear-side contact cells (PERCs) are capturing a growing photovoltaic market share, with a trend to replace monofacial device. Here, we reported five different rear pyramidal light trapping structures prepared by acid etching, with the monofacial counterparts as a comparison. The impact of the rear pyramid angles on the efficiency between under front and rear illumination shows an opposite trend due to a wavelength-dependent optical performance. To accurately optimize devices in real outdoor environments, the photovoltaic performance of mofacial and bifacial PERCs at different incident angles is simulated and integrated with an omnidirectional efficiency. Consequently, a significant improvement in bifaciality under omnidirectional incidence is obtained compared to vertical incidence, and a rough surface structure yields the maximum bifacial gain when the albedo is greater than 30 %. Furthermore, the power yield of monofacial and bifacial devices was predicted for every day in 2022.

Performance evaluation of PUC7‐based multifunction single‐phase solar active filter in real outdoor environments: Experimental insights

AbstractThis paper presents a novel architecture to enhance the performance of grid‐connected photovoltaic (PV) systems through the introduction of several key novelties. Firstly, a packed U‐cell seven‐level (PUC7)‐based single‐phase solar active filter is implemented, offering a comprehensive solution for harmonics mitigation, reactive power compensation, and efficient power extraction from the PV source, while facilitating the injection of real power into the grid. Secondly, the p‐q power injection algorithm is modified to accommodate the extraction of solar power from the PV generator to the grid, simultaneously addressing the need for harmonic current injection to improve power quality. This modification ensures dynamic performance by extracting reference current with harmonic content and solar power information, thereby enhancing the system's overall efficiency. Lastly, the proposed architecture undergoes real outdoor testing, validating its performance in various key aspects including maximum power tracking, reduction of total harmonic distortion in comparison with previous work, operation at unity power factor, and testing the effective operation of the multifunction feature. These contributions collectively demonstrate the effectiveness of the proposed system in enhancing power injection quality and reactive power compensation under real outdoor conditions of PV systems connected to the grid.

Photovoltaic cooling and atmospheric water harvesting using a hygroscopic hydrogel

Photovoltaic power generation technology has gained significant attention from researchers due to its advantages of simple structure, environmental friendliness, and high sustainability. However, the photon-to-electron conversion efficiency (PCE) of photovoltaic (PV) panels is limited by the residual heat produced during the solar absorption process. Thus, an effective heat management is vital for the long-term stable and efficient photovoltaic system. In this paper, a novel dual-function device was proposed to realize effective cooling of PV panels and harvest freshwater from the air simultaneously. Through the utilization of evaporative cooling with hygroscopic hydrogel, the photovoltaic cooling-water generator (PVC-WG) device achieves up to 8 °C reduction in the operating temperature of PV panels along with a freshwater generation rate of 122.32 g m−2 h−1 in the laboratory at solar intensity of 1 kW m−2. At night, the hygroscopic hydrogel automatically absorbed moisture from the air to achieve self-regeneration, confirming its excellent reusability. Even in real outdoor environments, a maximum cooling effect of 9.2 °C and a stable freshwater generation of 98.08 g m−2 day−1 could be achieved. The system not only accomplishes thermal management for PV panels but also attains additional freshwater generation, which enhances the efficiency of harnessing the entire spectrum of solar energy.

A Polymer Nanocomposite with Strong Full-Spectrum Solar Absorption and Infrared Emission for All-Day Thermal Energy Management and Conversion.

Realizing efficient energy utilization from the heat source of the sun and the cold source of outer space is of great significance for addressing the global energy and environmental crisis. Materials with ideal full-spectrum solar absorption and infrared emission are highly desirable for adapting to the continuous weather dynamic throughout the day, nonetheless, their development remains challenging. Here, a polymer nanocomposite with full-spectrum strong solar (280-2500nm) absorption ranging from 88.8% to 94.8% with an average value of 93.2% and full-spectrum high infrared (8-13µm) emission ranging from 81.3% to 90.0% with an average value of 84.2%, is reported by melt-processing polypropylene and uniformly dispersed low-loading MXene nanosheets (1.9 vol%). The nanocomposite can achieve daytime photothermal enhancement of ≈50 °C and nighttime radiative cooling of 8 °C. The temperature difference throughout the day ensures all-day uninterrupted thermoelectric generation, yielding a power density output of 1.5W m-2 (daytime) and 7.9mW m-2 (nighttime) in real outdoor environment without any additional energy consumption. This work provides an impressive polymer nanocomposite with ideal full-spectrum solar absorption and infrared emission for all-day uninterrupted thermal energy management and conversion.

Thermal comfort characteristics of a catalytic combustion heater under wind-chilled exposure

Heating in wind-chilled environments is a serious task. The catalytic combustion heater (CCH) provides more efficient and cleaner in combustion compared to conventional heaters with high pollutant emission and low energy utilization. In this paper, the heating ability of CCH on human body in a wind-chilled environment (apparent temperatures between −14.8 °C and 12.4 °C) was investigated by collecting skin temperature and subjective thermal evaluation data from 23 subjects. The impact of cold air on localized heating of body parts by CCH was clarified using decision trees and dimensionless correlation coefficients. A human-computer interaction regulation strategy was proposed to simultaneously satisfy the requirements of effective heating, low energy consumption, and low pollution. Finally, CCH and a commercial heater were compared in terms of heating effectiveness and energy consumption in a real outdoor environment. The results showed that CCH effectively solved the problem of excessive cold extremities, and the temperature difference between thoracoabdominal area and extremities was reduced by 57.5–87.9% to within 2 °C. In a strong convective environment, wind speed was the decisive factor (coefficient of 0.95), inducing 46% radiant heat loss. Inputting personnel subjective perception, dynamic environmental parameters, and pollutant thresholds to adjust the injected gas flow enabled intelligent control. In a real cold scenario, the CCH saved 65.9% of energy compared to a commercial heater when achieving the same heating effect. This study provides a reference for the application of catalytic combustion technology in cold outdoor heating and also provides an important theoretical basis for the construction of heating strategies for CCH.

EXPERIMENTAL AND COMPUTATIONAL STUDY ON THERMAL PERFORMANCE OF WOOD-PLASTIC COMPOSITES IN BUILDING ENVELOPE

Wood-plastic composites (WPCs) are attractive material for enhancing thermal performance of buildings by acting as an insulation surface. A fast and reliable experimental method was devised using a simple quasi-steady heating film (QSHF) method to measure the thermal conductivity of locally manufactured WPCs in Kuwait. QSHF used two blocks of standard materials compared with the classic methods, although it does not require a fixed constant heating source nor a cooling source. QSHF had a 10 cm × 10 cm × 0.5 mm silicon heating film controlled by a temperature controller and several transparent acrylic square blocks of the same size with 10 mm thickness as the standard materials. The top surface of the WPC samples was the cold side of the system, which is open to indoor temperatures of 22-23°C. The bottom layer can be maintained at any desirable temperature ranges from 25° to 55°C using the heating film to simulate the real outdoor environment. The thermal conductivities of locally manufactured WPCs type, namely FB16, FB18W, CD, and TD, were 0.0912, 0.1174, 0.3453, and 0.3078 W/m.K, respectively, obtained within 1 to 3 hours, which all fall below the standard value of 0.414 W/(m<sup>2</sup>.K) for composite walls and 0.1-0.2 W/m.K for wood. Multiphysics CFD simulation for DP45 sample and TRNSYS simulation for FB18W WPC in the building envelop were conducted which showed strong 2D effects and 3.3&#37: reduction in maximum cooling load in Kuwait, respectively.

Preparation and properties of one-component polyurea composite phase change cooling coating for asphalt pavement

To reduce the high-temperature distress of asphalt pavement and alleviate the urban heat island effect, one-component polyurea composite phase change cooling coating was prepared. Through the tests of storage time, curing time, hardness and tensile property, the performance variation of one-component polyurea under different latent curing agent dosage were analyzed. Through the tests of road performance and thermoregulation performance, the change rule of road performance and cooling effect of one-component polyurea composite phase change cooling coating under different amount of phase change particle admixture and coating were analyzed. The results showed that the phase-change cooling coating prepared in this study can meet the requirements of road performance. When the dosage of phase change particles is 20% and the amount of coating is 1.2 kg/m2, the maximum cooling effect of the coating reached 3.7 °C under the simulated indoor conditions and 3.3 °C under the real outdoor environment.

Special Issue on Autonomous Robotics Challenge

The Tsukuba Challenge and the Nakanoshima Robot Challenge are both technical challenges in which mobile robots run autonomously in real outdoor environments. They have been held almost every year since 2007 and 2018, respectively, and many robots have participated in these public experiments. The autonomous navigation of a mobile robot in the real world, that is, not on test tracks but in environments normally used by everyday people, poses a great many challenges. The robots have to deal with environments that change with the time of day, the weather, the season, etc., and they have to deal with unexpected stationary obstacles as well as moving ones, including people, bicycles, etc. These days, demonstration tests of delivery robots are being conducted in many places, but there are still many problems that need to be solved. In this special issue, we have gathered papers detailing the insights gained from running mobile robots in the two outdoor experiments, the Tsukuba Challenge and the Nakanoshima Robot Challenge. To run a robot with a high success rate in a real environment, it is very important to devise the robot configuration, the sensor data processing, and the behavior control based on the knowledge gained from many experiences. We hope that sharing the successes and failures in the papers in this special issue will lead to further technological improvements in the future.

Lessons from robot‐assisted disaster response deployments by the German Rescue Robotics Center task force

AbstractEarthquakes, fire, and floods often cause structural collapses of buildings. However, the inspection of such damaged buildings poses a high risk for emergency forces or is even impossible. We present three recently selected missions of the Robotics Task Force of the German Rescue Robotics Center (DRZ), where both ground and aerial robots were used to explore destroyed buildings. We describe and reflect the missions as well as the lessons learned that have resulted from them. To make robots from research laboratories fit for real operations, realistic outdoor and indoor test environments were set up at the DRZ and used for tests in regular exercises by researchers and emergency forces. On the basis of this experience, the robots and their control software were significantly improved. Furthermore, expert teams of researchers and first responders were formed, each with realistic assessments of the operational and practical suitability of robotic systems.

Macro-porous structured aerogel with enhanced ab/desorption kinetics for sorption-based atmospheric water harvesting

Sorption-based atmospheric water harvesting (SAWH) has been proven to be a promising method to alleviate the impact of the water crisis on human activities. However, the low water-sorption capacity and sluggish ab/desorption kinetics of current SAWH materials make it difficult to achieve high daily water production. In this study, a photothermal porous sodium alginate-tannic acid-5/Fe3+@lithium chloride aerogel (SA-TA-5/Fe3+@LiCl) with macroporous structure (average pore diameter ∼43.67 μm) and high solar absorbance (∼98.4 %) was fabricated via Fe3+-induced crosslinking and blackening methods. When it is employed for SAWH, moisture can enter the inner space of the aerogel and contact highly hygroscopic lithium chloride (LiCl) more easily via macroporous channels, resulting in the water uptake for the SA-TA-5/Fe3+@LiCl aerogel reaching approximately 1.229 g g−1 under dry conditions (relative humidity (RH) ∼ 45 %, 25 °C) after a short time (4 h) moisture absorption, and releasing as much as 97.7 % of the absorbed water under 1 sun irradiation within 2 h. As a proof of concept, it is estimated that the daily water yield of the fabricated SA-TA/Fe3+@LiCl aerogel can reach approximately 4.65 kg kg−1 in conditions close to the real outdoor environment (RH ∼ 45 %, 25 °C), which satisfies the daily minimum water consumption of two adults. This study demonstrates a novel strategy for developing advanced solar-driven SAWH materials with enhanced ab/desorption kinetics and efficient water sorption–desorption properties.

Utility of the Actiwatch Spectrum Plus for detecting the outdoor environment and physical activity in children

PurposeTo describe the performance of the Actiwatch Spectrum Plus (Philips, Respironics) for determining real world indoor and outdoor environments and physical activity in children. MethodsChildren wore the device while performing 10 different activities, ranging from sedentary to vigorous physical-activity, and under different indoor and outdoor conditions. Repeated measures ANOVA was implemented via mixed effects modeling to determine illuminance (lux) and physical activity (counts per 15 s, CP15) across conditions. Receiver operator characteristics (ROC) analysis assessed the accuracy to detect indoor versus outdoor settings. ResultsIlluminance was found to be statistically different across indoor (793 ± 348 lux) and outdoor (4,413 ± 518 lux) conditions (P<.0001), with excellent diagnostic accuracy to detect indoor versus outdoor settings (Area under the ROC Curve, AUC 0.94); 1088 lux was identified as the optimal threshold for outdoor illuminance (sensitivity: 93.0%; specificity: 85.0%). Using published activity ranges, we found that when children were sitting, 94% of the physical-activity readings were classified as sedentary or light. When children were walking, 88% of readings were classified as light, and when children were running, 77% of readings were classified as moderate or vigorous. ConclusionThe Actiwatch Spectrum Plus performed well during real world activities in children, showing excellent diagnostic accuracy at 1088 lux as a threshold to detect indoor versus outdoor environments and in categorizing physical activity.

Real time two-wheeler recognition for Surveillance

In today’s intelligent transportation systems, vision-based traffic tracking systems and automatic vehicle make and model recognition is of significant importance for surveillance. From the literature, vehicle make and model recognition has been implemented for four wheelers easily due to the presence of logo in the frontal and rear parts. But it is not feasible for two wheelers due to the insignificant differential features. Hence in this work, a robust two-wheeler recognition system has been developed with frontal, rear and side images of two wheelers which is implementable in edge devices. The contributions of the paper are (i) Development of a two-wheeler dataset with the frontal, rear and side images of two classes in Indian Scenario. (ii) Development of a two-wheeler recognition framework implementable in Raspberry pi-based devices. (iii) Evaluation of the framework in real time outdoor environment. From the experimental results it is observed that the proposed network classifies two wheelers in real time at 4s with 94% accuracy.

Nonlinear back-end optimization method for VSLAM with multi-convex combined maximum correntropy criterion

Back-end optimization plays a key role in eliminating the accumulated error in Visual Simultaneous Localization And Mapping (VSLAM). Existing back-end optimization methods are usually premised on the Gaussian noise assumption which does not always hold true due to the non-convex nature of the image and the fact that non-Gaussian noises are often encountered in real scenes. In view of this, we propose a back-end optimization method based on Multi-Convex combined Maximum Correntropy Criterion (MCMCC). A MCMCC-based cost function is first tailored for nonlinear back-end optimization in the context of VSLAM and the optimization problem is solved through Levenberg–Marquardt algorithm iteratively. Then, the proposed method is applied to ORB-SLAM3 to test its performance on public indoor and outdoor datasets. The real time performance is also validated using a RaceBot platform in real indoor and outdoor environments. In addition, the reprojection error is statistically analyzed to demonstrate the non-Gaussian characteristics in the back-end optimization process. Finally, the suggestion parameters are also provided through experiments for further study.

Color filter effects on the performance of monocrystalline and polycrystalline photovoltaic solar panels

We evaluated effect of different color filters on the electric production performance of monocrystalline and polycrystalline solar photovoltaic panels in real outdoor environment. In the experiment, we used four different color filters from blue to red on photovoltaic panels to observe energy and efficiency performance of the mono and polycrystalline solar photovoltaic panels as well as temperature of the panels measured with and without filters. We observed the wavelength dependence of monocrystalline photovoltaic panel is more effective than the polycrystalline photovoltaic panel one. For both panels we see that yellow color filtered produced the highest power value and have the lowest temperature value. This can be explained with that the spectrum of yellow color filter covers most of the radiation of solar but blocking infrared and ultraviolet side of the sun spectrum. This also causes the lower panel temperature. On the other hand, we observed that photovoltaic panels with blue color filter have the highest temperature value and the lowest power value. By the study we suggest that by optimizing the semiconductor band gaps in photovoltaic panels respect to solar wavelength, one can produce photovoltaic panels with higher efficiency by using filters, especially in hot climate regions. We expected that the results will also contribute to a better analysis of the points that need to be developed during the photovoltaic panel production stages.

Hygrothermal Performance of Thick PCM Mortar behind PV Panels in Energy-Activated ETICS Facades

The concept of integrating PV panels into traditional ETICS facades has been developing for several years. Problems concerning the options for passively controlling the temperatures of PV panels with PCM and directing excess moisture out of the wall via diffusion channels have been previously studied theoretically. During this study, real wall-scale experiments were conducted to test the thermal and hygrothermal performance of the wall system in an extreme climatic environment, as well as in a real outdoor environment in Tallinn, Estonia. Finally, a simulation model was calibrated according to the measured data. It was found that in case of test walls with diffusion channels, it was possible to keep the moisture content of PCM mortar under 0.11 m3/m3. Excess water drained out via channels leading to the external environment. Without diffusion channels, the moisture content rose as high as 0.18 m3/m3. Both the experiments and hygrothermal modelling showed that the high moisture content of PCM mortar, caused by water leakage, dropped to 0.08 m3/m3 over 10 solar cycles as moisture escaped via the diffusion channels. PCM mortar with a moisture content of 0.08 m3/m3 endured extreme rain and freeze-thaw cycles without visual damage, and PV panels retained their electrical production capabilities.

Coupling of Fe-N-C single atom catalyst and ferrocene-modified graphitic carbon nitride as an efficient photocatalyst for removal of pollutants from water

Graphitic carbon nitride (CN) is a promising photocatalyst in wastewater treatment field; however, CN suffers from sluggish photogenerated charge separation. Herein, a single atom catalyst (Fe-N-C) coupled with ferrocene-functionalized CN (CN-Fc) heterostructured composite (FCF-0.05) with superior photocatalytic activity was fabricated. Bisphenol A (BPA) can be removed completely over FCF-0.05/PMS/Vis system within 60 min, the corresponding apparent rate constant (k) was 24 times and 10 times higher than those of CN/Vis and CN/PMS/Vis systems, respectively, which was derived from the efficiently charge separation since generated interfacial heterojunction. Moreover, FCF-0.05/PMS/Vis system exhibited high stability and superior catalytic activity in real water and outdoor environment. Furthermore, the BPA degradation mechanism and pathway have been identified by combination experimental (quench testing, electron paramagnetic resonance and liquid chromatography-mass spectrometry techniques) and density functional theory (DFT) calculations method, providing insight of synthesis of cost-effective photocatalyst with outstanding catalytic activity.

E-Nose design and structures from statistical analysis to application in robotic: a compressive review

Since 1982, the olfactory system of creatures has piqued the interest of academics who seek to create a comparable system. Despite its mysterious nature, the first stage has been successfully completed with the development of the E-nose. Its extended applications have opened new doors for researchers, ranging from food quality testing to bomb detection and even, more recently, identifying those infected with the coronavirus. In this talk, we will review the structure and sensor behavior of the E-nose, as well as its applications, such as odour source localization and various applications in agriculture. The challenge of odour identification has prompted researchers to employ robots with sensors to investigate and locate odour sources. The present study aims to synthesize documented research and provide a fresh perspective on odour localization research efforts and tests conducted. The study highlights previous attempts to equip robots with sensors to explore the real indoor or outdoor environment. Initially, a review was conducted to investigate various aspects of the sector and the obstacles involved.

On the generation of full-scale urban pedestrian level wind in the wind tunnel using passive and active turbulence generators

The utilization of outdoor spaces is affected by their thermal environment. Wind, which determines the convective and evaporative heat loss from the human body, is one of the most influencing factors of thermal comfort. In the prevailing outdoor thermal comfort models, the convective heat transfer coefficients were pre-measured on a thermal manikin in a wind tunnel, where the wind speed was mostly stable. However, field measurements suggested that a typical outdoor wind process over complex terrains, like urban landscapes, are generally non-stationary. There is no experimental data on how the misrepresentation of wind may affect the convective heat transfer prediction for outdoor thermal comfort prediction. This study simulates urban pedestrian-level wind patterns in a wind tunnel by employing active and passive turbulence generators. Results show the turbulence scale through an active gust generator is approximately one to two orders of magnitude larger than the turbulence scale through a passive grid system. The eddy length scale can be adjusted through the rotation speed of the shutters. This opens the possibility of performing studies on measuring convective heat transfer coefficient under unsteady wind conditions, similar to the real outdoor environments.

Path-Analysis-Based Reinforcement Learning Algorithm for Imitation Filming

Imitation filming has been applied to autonomous filming by mimicking human operators. To imitate the operation of cameramen when filming multiple human actions, existing methods plan the camera motion through time series prediction or train multiple models to handle a particular style in a specific situation. As a result, these methods require various settings to adapt to different scenarios. In this work, we overcome such limitations and propose an end-to-end imitation learning framework for drone cinematography systems. The framework consists of two main components: (1) an efficient motion feature extraction module for generating a compact motion feature space, (2) a path-analysis-based reinforcement learning (PABRL) algorithm for imitating multiple filming styles from demonstrations and incorporating aesthetical features for improved perspective shots. Our PABRL method is based on the actorcritic network, which regards multiple human motion variables, camera translations, and image composition as inputs and then outputs an aesthetical filming strategy related to the subject motion. In addition, we propose an attention mechanism and a long-short-term rewarding function to enhance the motion feature space and the integrity of the generated trajectory, respectively. Extensive experimental results in simulated and real outdoor environments demonstrate that compared with state-of-the-art methods, our method can achieve 69.8% higher performance in terms of trajectory planning accuracy while successfully incorporating aesthetical features into the captured videos.