Fault Detection and Diagnosis (FDD) for photovoltaics (PV) is crucial to ensure the stable and efficient operation of PV systems. Current FDD strategies tend to rely on mono-electrical or thermal characteristics for single fault discrimination, while leaving compound faults untapped, due to the complexity of fault interaction. This study systematically modelled and investigated the thermal-electrical characteristics of 15 compound faults based on a dynamic thermal-electrical coupled simulation platform. The results indicated that the I-V and temperature characteristics of one fault may be retained, masked, amplified or weakened when coupled with another fault. Fault characteristics of aging, shading and hotspot were clearly combined in the compound faults, when individual faults occurred at different PV modules. However, when the hotspot was introduced to PV modules with aging or shading faults, the I-V characteristics of aging or shading were masked. Similar fault characteristic masking occurred when faulty PV modules were coupled with intra-string short-circuit faults and located within the short-circuited region. In the circumstances, the PV temperature distributions can play a significant role in fault diagnosis. When inter-string short-circuit was coupled with other faults, the number and locations of normal and faulty PV modules in different regions affected the dominant characteristics. The thermal-electrical characteristics among different compound faults investigated can provide expert knowledge to facilitate further FDD of compound faults in PVs.

Nitrogen, as a clean and naturally occurring inert gas, demonstrates significant potential in fire suppression due to its outstanding characteristics—including zero Ozone Depletion Potential (ODP) and Global Warming Potential (GWP), no residue, no corrosion—along with its safety advantages such as high-temperature stability, non-toxicity, and non-corrosiveness. Previous studies have predominantly focused on individual agents, and a systematic comparison of the performance trade-offs between nitrogen and other typical extinguishing agents remains lacking. This study systematically compares nitrogen with other typical gaseous fire extinguishing agents (CO2, Halon 1301, IG541, HFC-227ea, and Novec 1230) in terms of key performance metrics, thereby providing guidance for its applicability. The research indicates that the extinguishing efficiency of nitrogen is generally lower than that of agents relying on chemical inhibition. Due to its purely physical oxygen-dilution mechanism, nitrogen must be maintained at an extinguishing concentration of 31%-33.6%, which is significantly higher than that of Halon or its substitutes, such as HFC-227ea (8%-10%). This high concentration demand directly results in relatively slower extinguishing speed, and it is ranked last in suppressing vent gas flames from lithium-ion batteries (LIB). Additionally, nitrogen has an inherent weakness in cooling capacity; its purely physical process offers limited heat absorption, making it difficult to effectively reduce temperatures in deep-seated fires (e.g., coal mine goafs) or during continuous thermal runaway, with a high risk of reignition observed. However, in terms of safety, nitrogen exhibits unparalleled advantages. It completely avoids the ozone depletion associated with Halons, the strong greenhouse effect and toxic decomposition products of HFCs, the potential carbonic acid corrosion caused by the CO2 component in IG541, and the risk of HF generation from Novec 1230 under high temperatures. The applicability of nitrogen as a fire extinguishing agent should be positioned in enclosed or semi-enclosed scenarios with stringent requirements for environmental protection, personnel safety, and equipment compatibility.

Climate change poses new requirements for fire risk assessment, necessitating methods to quantify the impacts of environmental factors. As a high fire and explosion risk place, crude oil depot, typically exposed to open air, is highly susceptible to such factors. However, conventional risk assessment frameworks usually overlook the quantitative characterization of environmental factors' impacts. Furthermore, existing single-method frameworks are generally inadequate for quantitatively capturing complex and dynamic relationships between environmental factors and risk levels. In response, this study developed a risk assessment method that enabled the quantification of typical environmental factors' impacts on oil depot fire and explosion risk. Specifically, the method quantified impacts through these pathways that are air temperature-driven, increasing human error probabilities and relative humidity-dependent electrostatic sparks events. To achieve this, the method synergistically combined fault tree analysis, cloud model theory, and information diffusion technique. The results indicated that oil depot fire and explosion risk exhibited a parabolic curve opening upward against air temperature, reaching its minimum at 20 degrees C. In contrast, the risk decreased monotonically with increasing relative humidity. It was also known that the impacts of relative humidity were relatively much smaller than those from the air temperature, which can be ignored during the analysis of oil depot fire and explosion risk. In practical application, the assessment results support the development of a predictive risk chart, facilitating real-time risk forecasting and enabling customization based on regional climatic conditions. Under the background of climate change, the developed method fulfills the critical demand for reliable risk assessment under evolving weather conditions.

Effectively utilising solar facades combined with natural ventilation is vital for future zero-carbon buildings. However, the thermal-flow coupling and natural convection mechanisms in multi-inlet vertical airflow networks remain unclear, obstructing ventilation designs and energy consumption evaluations. To address this gap, we investigated the inter-storey flow interference within multi-storey solar facades. A numerical model validated using existing results and Particle Image Velocimetry (PIV) experiments analyses the vertical cavity flow field. The result illustrates a non-linear impact of the flow confluence on the ventilation performance at different floors, with a flow area contraction of 41%, 58%, 66% and 74% on the 2nd to 5th floor, respectively. A mathematical model was hence developed to estimate the dynamic discharge coefficient (Cd_m) of multi-storey NVDSF. Based on the derived coefficients for multi-storey buildings, we proposed to establish a ventilation satisfaction rate based on the air change rate (ACH). Through the analysis of annual climate data from two cities, we obtained ventilation satisfaction that is jointly influenced by floor-wise confluence coefficients and outdoor solar radiation intensities, thereby providing a more accurate analytical basis for assessing the natural ventilation potential and energy saving rates for multi-storey buildings.

Previous studies on solar chimneys have primarily focused on single-room or simplified multi-zone buildings, and their applicability to multi-room structures with complex coupled airflow paths remains unknown. This study investigates the performance of solar chimneys in multi-room buildings. Numerical simulations are conducted to analyze the effects of forced and unforced vent sizes, revealing the influence of key design parameters, and a theoretical model is developed to predict their performance. The results show that internal vent configuration plays a dominant role in ventilation performance. A minimum vent height of 0.2 m is required to achieve 6 ACH in a corridor connected to four rooms, while positioning the forced vent approximately 0.1 m higher than the unforced vent enhances ventilation performance with improved design efficiency. Arranging forced and unforced vents in parallel shortens airflow paths and increases airflow efficiency by 10.2-13.7%. Unlike single-room systems, the ventilation rate in multi-room buildings exhibits a parabolic relationship with inlet height and cavity width, with optimal values around 0.2-0.3 m, resulting from the balance between buoyancy-driven flow and increased resistance along extended airflow paths. Excessively high inlet positions weaken thermal buoyancy and reduce chimney performance. Increasing window size improves ventilation by up to 11%, although further enlargement leads to diminishing returns. The proposed theoretical model demonstrates good predictive capability for airflow performance in multi-room configurations. This study addresses the lack of theoretical understanding of multi-room solar chimneys and provides a basis for their optimized design and application.

Gaseous nitrogen is a widely used gaseous extinguishing agent valued for its low cost, environmental friendliness, and residue-free properties. However, while previous studies have focused on improving its efficiency or optimizing parameters, a systematic review of its scenario-specific limitations and mitigation measures is lacking. To address this gap, the limitations of gaseous nitrogen were categorized into four dimensions: physical properties, scenario adaptability, system design, and standardization. Specifically, its lack of chemical inhibition and weak cooling capacity increase reignition risks and dosage needs; complex spatial geometries hinder uniform gas distribution, creating inerting blind zones; high-pressure storage increases system complexity and cost; and absent standardized parameters restrict synergistic technologies' application. Furthermore, this review delineates strict application boundaries: gaseous nitrogen is prohibited for reactive metal fires due to the risk of exothermic reactions and is unsuitable for deep-seated smoldering fires owing to inadequate penetration and cooling capabilities. Additionally, extreme caution regarding asphyxiation risks is required when applying it in occupied spaces or high-altitude environments. Consequently, the inherent absence of chemical scavenging capability and limited heat absorption capacity restricts gaseous nitrogen's standalone viability, necessitating its integration with synergistic technologies. This review thus provides a guiding framework for application selection and suggests future research directions.

Evaporation potential, generated by the evaporation of water, can be harnessed for energy generation. In bamboo, vascular bundles provide clear pathways for rapid moisture transportation. Meanwhile, the abundance of hydroxyl and carboxyl groups on the wall of vessels and sieve tube enable cation-selective conduction during this process, thereby establishing a potential difference. Leveraging this mechanism, a bamboo-based hydro-voltaic generator (BHG) was designed and fabricated. The stem of moso bamboo was selected as the medium for evaporation, and a copper grid with carbon paste as the electrodes. In deionized (DI) water, the BHG provided a stable open-circuit voltage (VOC) of 86 mV, a short circuit current density (JSC) of 1.438 & micro;A center dot cm-2, and a maximum areal power (PMA) of 0.083 & micro;W center dot cm-2. The performance of BHGs was significantly improved in salt solutions. With 3.5 wt% potassium chloride (KCl) solution, a single BHG yielded a stable VOC of 381 mV, JSC of 1.85 & micro;A center dot cm-2, and PMA of 12.66 & micro;W center dot cm-2. Furthermore, the output power could be enhanced by connecting multiple BHGs in series. A series connection of five BHGs provided a stable open circuit voltage between 1.6 and 1.7 V, which was sufficient to power a red light-emitting diode (LED) for over 24 h.

Fractional vegetation coverage (FVC) is an important indicator for measuring ecosystem function and environmental quality. This study, using MODIS data from 2001 to 2022, investigates the spatiotemporal dynamics, driving factors, and predictive performance of FVC in Anhui Province of China. The results show that over the past 20 years, FVC in Anhui has significantly increased, with more than 80% of the region showing an upward trend, and 47.72% of the area experiencing highly significant increases, while less than 7% showed a decline. The annual mean FVC increased from 0.64 to 0.74, exhibiting a clear spatial gradient of "high in the south, low in the north." Feature correlation analysis revealed that temperature and evapotranspiration are the main environmental drivers of FVC. Temperature can promote the growth of vegetation and increase its coverage, while evapotranspiration is closely related to regional water stress. In the established predictive modeling, the XGBoost algorithm outperformed random forest and ridge regression, demonstrating the best predictive performance on the validation set (R 2 = 0.83). While the individual analytical methods employed are well-established, the primary innovation of this study lies in constructing an integrated framework that bridges traditional long-term spatiotemporal statistics with advanced ensemble machine learning. This methodological integration successfully transitions regional vegetation analysis from retrospective observation to high-precision dynamic forecasting. Ultimately, by accurately forecasting vegetation trends under varying thermal and moisture conditions, this research fills a critical gap in Anhui Province, providing robust, data-driven support for climate change adaptation strategies, targeted afforestation planning, and sustainable land-use policymaking.

Thermal runaway presents one of the most formidable safety challenges for lithium-ion batteries, and once initiated, preventing its propagation becomes crucial. This review dissects the mechanisms, modeling methodologies, and mitigation strategies for thermal runaway propagation across both module and pack scales. It identifies the governing thermal, chemical, and mechanical factors that drive propagation and establishes the theoretical foundations for its modeling and control. The discussion advances through an in-depth assessment of phase change materials, aerogels, and other multifunctional composites designed to suppress heat transfer and flame spread, emphasizing their synthesis, property enhancement, and performance metrics. Experimental and computational studies integrating cooling technologies reveal how synergistic designs combining advanced materials with dynamic cooling can effectively arrest propagation. The review further evaluates and compares the mechanisms and quantitative efficiencies of various fire-suppressing agents in halting propagation. Two central innovations distinguish this work: first, the evolution of mitigation materials from single-function insulators into adaptive, multifunctional protection systems; and second, the convergence of materials science, thermal management, and fire engineering into a unified, multi-dimensional strategy. By bridging these disciplines, the review defines a forward-looking framework for next-generation battery safety and delivers practical insights to guide the development of high-efficiency, resilient lithium-ion energy systems.

Global warming intensifies urban heatwave risks. However, current climate projections treat urban and rural areas equally, overlooking the impacts of the urban heat island (UHI) effect on future heatwave risk. As the present UHI intensity models show limitations in a global-scale analysis, urban heatwave risks under the joint effect of global warming and UHI effect remain unknown. Here we quantify the joint effect on the heatwave risks of 1600 cities worldwide, each with over 300,000 inhabitants. We find that, even under the most optimal sustainable development pathway (i.e., Shared Socioeconomic Pathway 1-2.6, SSP1-2.6), the average urban temperature of the analyzed cities increases by (2.23 f 0.03) degrees C (mean f se), which amounts to 124% of the value induced by the global warming projection alone (i.e., (1.8 f 0.01) degrees C). We estimate that the joint effect elevates the excess mortality risk (EMR) to (2.2 f 0.1)% in summer 2100, while the EMR in summer 2015 is only (0.8 f 0.02)%. The frequencies of building, outdoor and vehicle fires of the analyzed cities change by (-0.6 f 0.1)%, (5.1 f 0.1)% and (4.9 f 0.1)%, respectively. We find that although the UHI effect increases air temperature in approximately 81% of cities worldwide, global warming dominates the heatwave risks in 99% of all analyzed cities under SSP1-2.6. Our results highlight that action plans and policies that neglect the joint effect may offer fault promises of heatwave mitigation.

Partial shading (e.g., bird droppings, leaves, dusts, and shadows) on solar photovoltaic (PV) panels not only depresses the energy performance of solar PV panels but also increases their surface temperature. Nowadays, the impact of shaded locations is overlooked, and the quantitative relationship between surface temperature and energy performance of solar PV panels under partial shading is still unknown. This has hampered the solar PV panels' energy output prediction, which is especially important for ensuring their widespread applications. Hence, this study experimentally addressed the impacts of partial shading with variations in shaded ratios and shaded locations on solar PV panels' surface temperature and energy performance. Experimental results showed that the worst scenario was at the upper right cell under 67 % shaded ratio, causing the shaded cell's surface temperature to reach 99.6 degrees C under 1100 W/m2 solar irradiance and 20 degrees C ambient temperature. However, the power of solar PV panel could decrease up to 92.9 % when the middle cell was completely shaded. From both aspects of surface temperature and power dissipation of solar PV panels, the potential reduction of energy performance was worse when the middle or bottom cells were shaded. The quantitative relationship describing power dissipation affecting temperature at shaded cell caused by partial shading was also proposed. The obtained results contribute to predicting energy outputs considering typical partial shading scenarios and offer valuable data supporting decision-making and policy formulation aimed at minimizing energy losses in solar PV systems.

Previous studies on multi-storey solar chimneys usually overlooked the external wind influence. This study quantifies the external wind effects on the ventilation performance of multi-storey solar chimney. Simulations analyze the performance of solar chimneys under varying wind speeds and directions, comparing the ventilation efficiency across buildings with different floor counts, and revealing the change pattern of wind influence with the number of building floors. Results showed that wind direction and velocity are critical to multi-storey solar chimney performance. On the windward side, an increased wind velocity enhances the airflow into air inlets of each floor linearly. Optimal wind direction occurs when the wind is perpendicular to window, which maximizing airflow rate and reducing uneven distribution. Higher floors are more sensitive to wind speed and direction changes compared to lower floors. Conversely, the leeward side should be avoided, as wind it weakens airflow rate and reduces overall performance. The interaction between wind and building floors is also important. As the number of floors increases, the wind sensitivity of multi-storey solar chimneys decreases. A 2-storey solar chimney has higher chimneys and better wind energy utilization, can effectively replace single-storey solar chimneys. To optimize ventilation performance in windy, the inlet height should be increased to 0.4-0.6 m, and the cavity gap should be expanded to 0.7-1.5 m. A theoretical model was developed as well, which accurately predicts the solar chimney performance in multi-storey buildings. This study fills a critical gap regarding the ventilation effect of multi-storey solar chimneys in external wind, offering practical guidance for optimizing the designs of multi-storey buildings.

Shadow is an important hurdle to the power generation efficiency of solar photovoltaic (PV) modules. So far, most previous studies on this aspect have focused on simulation, lacking full-scale experimental study, not to mention the relevant quantitative experimental analysis. Therefore, this study conducted a full-scale outdoor experimental and empirical study on the PV modules under different shadow conditions. Experimental results revealed that the power generation capacity of a single-string PV module decreases by approximately 90 % when a specific solar cell is entirely obstructed. When a cell is shadowed, the short-circuit current drops by 20-25 %. The open-circuit voltage (Voc) drops by 25-30 % when 2/3 of the PV modules are shadowed. The short-circuit current (Isc) has a linear relationship with a smaller shadow less than a solar cell, and the Vochas a linear relationship with a shadow larger than a solar cell. However, the power generation efficiency exhibits a nonlinear relationship with the shadow ratio of the cells when they are subjected to shading. Based on the fullscale experimental tests, this study developed an empirical model, for the first time, to address the relationship between shadow ratio and power generation efficiency, where the power generation efficiency is negatively related to the 3/2 power of the shadow area. The obtained research outcome, together with the empirical model, can pave the way for future large-scale (e.g., global scale) study on addressing the impact of shadow conditions (e.g., bird droppings, dark clouds, gravel, and dust) on the power generation of solar PV systems.

Solar chimneys offer energy-efficient building ventilation, but their application in tunnels, especially for smoke extraction, remains underexplored. This study experimentally and theoretically investigates solar chimney performance in a tunnel under normal ventilation and fire conditions. Experiments systematically varied chimney geometry, solar radiation (200-1200 W/m2), and fire heat release rate. Results show vertical temperature inside the chimney follows a 1/4 power relationship with height, with thermal gradients improving in narrower cavities. Air inflow rate increased proportionally to the 1/3 power of solar radiation. Volumetric flow rate improved with chimney height and cross-section, with width having a greater impact than depth. Smoke exhaustion efficiency correlated strongly (R2 > 0.99) with a novel dimensionless parameter incorporating chimney geometry and fire power. A theoretical model incorporating an exponential vertical temperature profile accurately predicts volumetric flow rate for both ventilation and smoke exhaustion scenarios. These findings provide validated tools for evaluating and optimising solar chimney design in tunnels.

Amidst global warming and energy crises, low-carbon building design is essential. China, the largest carbon emitter, commits to peaking emissions by 2030 and achieving carbon neutrality by 2060. This study focuses on low-carbon strategies for industrial buildings in cold regions, aiming to develop optimization designs centered on carbon emissions. Using ENERGYPLUS and the “standard coal method”, it quantifies operational carbon emissions and analyzes the impact of design methods on energy consumption across architectural layout, materials, and photovoltaic technology. This study, set in Xi’an and Yulin, assesses low-carbon techniques in cold and severely cold climate zones. It demonstrates that, for the architectural layout, the orientation of the building has a relatively small impact on carbon emissions, while an increase in the window-to-wall ratio significantly increases the carbon emissions of the building. For the building materials, the form of window glass, the reflectivity of roofs and walls, and the thickness of roof and wall insulation significantly affect carbon emissions. For the photovoltaic technology, the angle of photovoltaic roofs has no significant impact on carbon emissions. By further comparing the effectiveness of various low-carbon design technologies in reducing building carbon emissions, it was found that choosing more appropriate wall insulation boards can provide more significant carbon reduction effects at the same cost.