Search Results (566)

This study assessed the impact of 39 active and passive energy efficiency measures on the energy demand of a prototype dwelling, modeled through parametric simulations in DesignBuilder across nine climatic zones in Chile, classified according to the Köppen system. Each measure was evaluated individually (single-measure scenarios); three variation levels were evaluated to quantify their relative influence on energy demand. Results indicate that passive strategies are more effective in cold and humid climates, where increasing wall insulation thickness reduced energy demand by up to 45%, and improving airtightness achieved a 43% reduction. In contrast, in tundra climates or areas with high thermal variability, some measures, such as green façades or overhangs, increased energy demand by up to 49% due to the loss of useful solar gains. In desert climates, characterized by high diurnal temperature variation, thermal mass played a more significant role: high-inertia walls without additional insulation outperformed lightweight EPS-based solutions. The findings suggest that measure selection must be climate-adapted, prioritizing high-impact passive strategies and avoiding one-size-fits-all solutions. This work provides quantitative evidence to inform residential thermal design and support climate-sensitive energy efficiency policies. This study delivers a single-measure comparative atlas; future research should integrate multi-measure optimization together with comfort/cost metrics. Full article

This study proposes a scenario-based conceptual model for transforming underground parking structures into sustainable interior green spaces, directly addressing two core research dimensions: energy efficiency and user experience. The originality of the research lies in repositioning subterranean spaces—often overlooked in urban planning—as climate-responsive, multi-functional public environments. Using a site-specific case in downtown Rize, Türkiye, three design scenarios—passive green walls, active modular systems, and experimental micro-farming—were comparatively analyzed. These scenarios were assessed through AI-assisted simulations and climate-based performance evaluations in terms of environmental benefits, thermal regulation, carbon reduction, and experiential quality. Underground space leads to green design interventions, which in turn generate environmental, energy, and social benefits. The results demonstrate that passive systems provide cost-effective improvements, active modular systems achieve balanced performance, and experimental micro-farming yields the highest ecological and social benefits. The study uniquely contributes to urban sustainable design by integrating climate-adaptive strategies, biophilic design principles, and AI-supported visualization into the transformation of underground structures. This research not only advances academic discourse but also provides policy-relevant insights for local governments, developers, and communities in the context of urban renewal. Full article

Hydrodynamic cavitation usually occurs in marine and ocean engineering and hydraulic systems and may lead to destructive effects such as an enhanced drag force, noise, vibration, surface damage, and reduced efficiency. Previous studies employed several passive and active control strategies to manage unstable cavitation and its adverse effects. This study reviews various passive and active control strategies for managing diverse cavitation stages, such as partial, cloud, and tip vortex. Regarding the passive methods, different control factors, including the sweep angle of the foil, roughness, bio-inspired riblets, V-shaped grooves, J grooves, obstacles, surface roughness, blunt trailing edge, slits, various vortex generators, and triangular slots, are discussed. Regarding the active methods, various injection methods including air, water, polymer, and synthetic jet and piezoelectric actuators are reviewed. It can be concluded that unstable cavitation can be controlled by both the active and passive approaches independently. However, in the severe conditions of cavitation and higher angles of attack, the passive control methods can only alleviate some re-entrant jets propagating in the downward direction, and proper control of the cavity structure cannot be achieved. In addition, active control methods mostly require supplementary energy and, consequently, lead to higher expenses. Combined passive active control technologies are suggested by the author, using the strengths of both methods to suppress cavitation and control the cavitation instability for a broad range of cavitating flows efficiently in future works. Full article

Soil moisture (SM) is a critical component of the global water cycle, profoundly influencing carbon fluxes and energy exchanges between the land surface and the atmosphere. NASA’s Soil Moisture Active/Passive (SMAP) mission provides soil moisture products at the global scale; however, validation of SMAP faces significant challenges due to scale mismatches between in situ measurements and satellite pixels, particularly in highly heterogeneous regions such as the Qinghai–Tibet Plateau. This study leverages high-spatiotemporal-resolution Harmonized Landsat–Sentinel-2 (HLS v2.0) data and the QLB-NET observation network, employing multiple machine learning models to generate pixel-scale ground-truth soil moisture from in situ measurements. The results indicate that XGBoost performs best (R = 0.941, RMSE = 0.047 m³/m³), and SHAP analysis identifies elevation and DOY as the primary drivers of the spatial patterns and dynamics of soil moisture. The XGBoost-upscaled soil moisture was employed as a validation benchmark to assess the accuracy of the SMAP 9 km and 36 km products, with the following key findings: (1) the proposed upscaling method effectively bridges the scale gap, yielding a correlation of 0.858 between the 36 km SMAP product and the pixel-scale soil moisture reference derived from XGBoost, surpassing the 0.818 correlation obtained using the traditional in situ averaging approach; (2) descending-orbit data generally outperform ascending-orbit data. In the 9 km SMAP product, 15 descending-orbit grids meet the scientific standard, compared to 10 ascending-orbit grids. For the 36 km product, only descending orbits satisfy the scientific standard. Full article

Battery Thermal Management Systems (BTMS) are essential for ensuring the performance, safety, and longevity of lithium-ion batteries (Li-ion) in electric vehicles (EVs). First, this review examines the current state of BTMS technologies, focusing on three thermal management strategies: passive, active, and hybrid thermal management strategies. Passive thermal management strategies, such as using phase change materials (PCM) or heat-conductive materials, offer simplicity and low energy consumption but are limited in high-power applications. The active thermal management strategies, including forced air cooling and liquid cooling, provide superior heat dissipation but require complex design and higher energy input. The hybrid thermal management strategies combine the advantages of passive and active strategies, providing a more suitable solution for the thermal management of lithium-ion batteries under diverse operating conditions. Second, the review also highlights challenges posed by high-energy density batteries, fast charging, and emerging battery technologies like solid-state and lithium–sulfur batteries. Finally, the technical summary draws from the research status of BTMS and future development directions are proposed. Full article

Small-scale wind turbines (SWTs) represent a promising solution for the energy transition and the decentralization of electricity generation in non-interconnected areas. Conventional strategies to improve SWT performance often rely on active pitch control, which, while effective at rated conditions, is too costly and complex for small systems. An alternative is passive pitch control through bend–twist coupling in the blade structure, which enables self-regulation and improved power generation. This work proposes a novel blade design methodology for a 5 kW SWT that integrates passive bend–twist coupling with conventional pitch adjustment, thereby creating a hybrid passive–active control strategy. The methodology encompasses the definition of aerodynamic blade geometry, laminate optimization via genetic algorithms combined with finite element analysis, and experimental characterization of composite materials. Aerodynamic–structural interactions are studied using one-way fluid–structure simulations, with responses analyzed through the blade element momentum method to assess turbine performance. The results indicate that the proposed design enhances power generation by about 4%. The study’s originality lies in integrating optimization, structural tailoring, and material testing, offering one of the first demonstrations of combined passive–active pitch control in SWTs, and providing a cost-effective route to improve efficiency and reliability in decentralized renewable energy systems. Full article

Objectives: To quantify the effects of geared wheelchair wheels on energy expenditure during manual wheelchair propulsion in individuals with spinal cord injury (SCI). Methods: Eleven adult manual wheelchair users with SCI propelled their personal manual wheelchairs, which were equipped with a pair of geared wheels, on a passive wheelchair ergometer in low-gear and standard-gear conditions for six minutes. The energy cost of transport, distance traveled, rate of oxygen consumption (SCI MET), rate of perceived exertion, heart rate, and stroke cycle frequency were measured and compared across the gear conditions. Results: The distance traveled and SCI MET were significantly lower (p = 0.003) and cost of transport was significantly higher under the low-gear condition compared with the standard-gear condition. Gear condition exerted a moderate effect on the level of exertion; however, the decrease in the rate of perceived exertion under the low-gear condition was not statistically significant. Gear condition did not significantly affect heart rate and stroke cycle frequency. Conclusions: Geared manual wheelchair propulsion was significantly more energy-demanding, but less intense (easier) under the low-gear condition than the standard-gear condition. Using geared wheels may be beneficial for manual wheelchair users to independently accomplish strenuous propulsion tasks during typical activities of daily living, such as propulsion on carpeted floor. However, the small sample size and inclusion of only male participants limit the generalizability of these findings, and future studies with larger and more diverse cohorts are warranted. Full article

This research investigates the integration of green cores as central biophilic elements in residential architecture, proposing a climate-responsive design methodology grounded in architectural optimization. The study begins with the full-scale refurbishment of a compact urban apartment, wherein interior partitions, fenestration and material systems were reconfigured to embed vegetated zones within the architectural core. Light exposure, ventilation potential and spatial coherence were maximized through data-driven design strategies and structural modifications. Integrated planting modules equipped with PAR-specific LED systems ensure sustained vegetation growth, while embedded environmental infrastructure supports automated irrigation and continuous microclimate monitoring. This plant-centered spatial model is evaluated using quantifiable performance metrics, establishing a replicable framework for optimized indoor ecosystems. Photosynthetically active radiation (PAR)-specific LED systems and embedded environmental infrastructure were incorporated to maintain vegetation viability and enable microclimate regulation. A programmable irrigation system linked to environmental sensors allows automated resource management, ensuring efficient plant sustenance. The configuration is assessed using measurable indicators such as daylight factor, solar exposure, passive thermal behavior and similar elements. Additionally, a post-occupancy expert assessment was conducted with several architects evaluating different aspects confirming the architectural and spatial improvements achieved through the refurbishment. This study not only demonstrates a viable architectural prototype but also opens future avenues for the development of metabolically active buildings, integration with decentralized energy and water systems, and the computational optimization of living infrastructure across varying climatic zones. Full article

Pipeline systems are essential across various industries for transporting fluids over various ranges of distances. A notable application is natural circulation through thermo-syphoning, driven by temperature-induced density variations that generate fluid flow in closed loops. This passive mechanism is widely employed in sectors such as process engineering, oil and gas, geothermal energy, solar water heaters, fertilizers, etc. Natural Circulation Loops eliminate the need for mechanical pumps. While this passive mechanism reduces energy consumption and maintenance costs, maintaining stability and efficiency under varying operating conditions remains a challenge. This study investigates thermo-syphoning in a rectangular closed-loop system and develops optimal control strategies like using a Linear Quadratic Regulator (LQR) and Model Predictive Control (MPC) to ensure stable and efficient heat removal while explicitly addressing physical constraints. The results demonstrate that MPC improves system stability and reduces energy usage through optimized control actions by nearly one-third in the initial energy requirement. Compared to the LQR and unconstrained MPC, MPC with active constraints effectively manages input limitations, ensuring safer and more practical operation. With its predictive capability and adaptability, the proposed MPC framework offers a robust, scalable solution for real-time industrial applications, supporting the development of sustainable and adaptive natural circulation pipeline systems. Full article

Climate change and extreme weather compromise building energy performance and Heating, Ventilation, and Air Conditioning (HVAC) systems, impacting occupant wellbeing and health. However, occupants can naturally adapt through their behaviors, representing a form of intrinsic resilience that enhances the building’s capacity to handle thermal extremes. This study explores the role of occupants in buildings’ thermal resilience; it begins by investigating passive and active strategies commonly discussed in the literature, then analyzes whether occupants are treated as passive or active subjects with adaptive capacity. Four databases were consulted, and 22 peer-reviewed papers were screened based on the following criteria: a clear definition of thermal resilient buildings, inclusion of at least one quantitative method for assessing whole-building resilience, original scientific contribution, and a focus on whole-building rather than component-level resilience. Analysis highlights that the intrinsic thermal resilience of occupants has received limited importance in current discourse on building resilience; in most studies (12 out of 22), occupants are treated as passive thermal loads, with no adaptive behavior considered. This study also suggests examining strategies traditionally used in energy efficiency and indoor comfort as a preliminary approach to encourage adaptive behaviors, and, above all, opens a discussion on integrating occupant behavior into resilience strategies. Full article

Thermal management in heat exchangers is crucial in many industrial, medical, and scientific applications. However, reducing dependency on active energy sources still represents a substantial challenge. In this context, phase change materials (PCMs) offer an effective solution due to their ability to store and release large amounts of latent heat, assisting in passive thermal management. Therefore, this study proposes the use of RT42 PCM inside a box-type shell-and-tube configuration to establish the relationship between flow rate and charging and discharging behavior of PCM. In the proposed system, heat transferring fluid (HTF) water is circulated in the internal tubes at 60 °C, where the temperature is monitored by a series of thermocouples strategically placed inside the box-type configuration. To evaluate the effect of the flow of HTF on the thermal behavior of the PCM, the charging (melting) and discharging (solidification) analysis is performed by varying the water flow rate at three levels: 1.2, 0.8, and 0.4 L/min inside the laminar region (Re < 2300). A thermal camera and two webcams were used to assess the surface temperature distribution and PCM response, respectively. It was determined that increasing the flow rate accelerates charging and discharging with fluctuations in temperature curves during melting. Full article

Deep hole structures are widely used in the fields of aerospace, engineering machinery, marine, etc. During the deep hole machining processes, especially for boring procedures, the vibration phenomenon caused by the large aspect ratio of boring tools seriously restricts the machining accuracy and production efficiency. Therefore, extensive research has been devoted to the design and development of damped boring tools with different structures to suppress machining vibration. According to varied vibration reduction technologies, the damped boring tools can be divided into active and passive categories. This paper systematically reviews the advancements of vibration reduction principles, structure design, and practical applications of typical active and passive damped boring tools. Active damped boring tools rely on the synergistic action of sensors, actuators, and control systems, which can monitor vibration signals in real-time during the machining process and achieve dynamic vibration suppression through feedback adjustment. Their advantages include strong adaptability and wide adjustment capability for different machining conditions, including precision machining scenarios. Comparatively, vibration-absorbing units, such as mass dampers and viscoelastic materials, are integrated into the boring bars for passive damped tools, while an energy dissipation mechanism is utilized with the aid of boring tool structures to suppress vibration. Their advantages include simple structure, low manufacturing cost, and independence from an external energy supply. Furthermore, the potential development directions of vibration damped boring bars are discussed. With the development of intelligent manufacturing technologies, the multifunctional integration of damped boring tools has become a research hotspot. Future research will focus more on the development of an intelligent boring tool system to further improve the processing efficiency of deep hole structures with difficult-to-machine materials. Full article

Considering that the information contained in the interference structure of the “target-receiver” path in active sonar is crucial for remote sensing of the target position or the environmental information, this paper studies the method for coherent extraction and enhancement of the interference structure of the scattered sound field using a monostatic horizontal line array (HLA) in deep water. The HLA element–frequency domain sound intensity interference pattern of the monostatic scattered sound field is numerically simulated, and the “cutting” effect on the pattern is explained by combining the scattered sound pressure expression. Then, the mechanism of the sound propagation effect of the “source-target” path on the interference structure of the “target-receiver” path is clarified. In deep water, the phase relationship of the HLA scattered sound pressure is derived based on the ray theory, and its similarity with the phase relationship of the array passive received signals affected by the source spectrum is researched. The method for the coherent enhancement of the interference structure between the target and the reference array element for the deep-water active sonar is proposed, which uses the phase information of the single-element (SE) signal to generate the array cross-correlation data and then performs striation-based beamforming on it (i.e., the striation–correlation-based beamforming with single element, SCBF-SE). The results of numerical simulation and sea trial data analysis show the effectiveness of this method for interference structure enhancement. The performance differences between SCBF-SE and the incoherent accumulation of the striation energy (IASE) method in interference structure enhancement are compared. The results indicate that SCBF-SE has better performance under the conditions of the same received signal-to-noise ratio and the number of array elements. Full article

Turkey is in the process of developing national strategies to reach the NZEB standard. There is a gap in the literature regarding the life-cycle costs of the passive and active solutions that increase energy efficiency and have significant potential in the widespread adoption of the NZEB standard. Therefore, this study aims to investigate the economic feasibility of improvement alternatives for an existing building in Turkey. In accordance with the objectives involved in achieving NZEBs, national standards (TS 825-2008, TS 825-2024) and passive and active improvement strategies under the EnerPHit framework were identified, and a residential building located in Izmir, which is in a warm climate zone, was modelled using DesignBuilder (version 7.3.1.003) software. A comparison of the current configuration with those predicted by TS 825-2008, TS 825 2024, and EnerPHit indicates energy savings of 29%, 36%, and 54%, respectively. In addition, the benefit–cost ratios, payback periods, and life-cycle costs of the alternatives were determined. The lowest LCC was determined to be the USD 5.424 for the improved EnerPHit-compliant alternative using PV integration. Moreover, it was determined that achieving a plus-energy building is possible even when electric vehicles are charged in the improved building. In Turkey, the retrofitting of buildings similar to that of the case study into plus-energy buildings has been deemed economically viable, provided certain EnerPHit-compliant improvements are implemented. Full article

Corrosion inhibitors can form dense, protective layers on metal surfaces, thereby preventing the penetration of corrosive media and ensuring the long-term safety of industrial equipment and energy facilities. Polyaniline (PANI), renowned for its excellent conductivity and redox activity, not only facilitates the formation of passivation layers on metals but also mitigates pitting corrosion. In this study, a novel doped PANI was synthesized through chemical oxidation using cyclic carboxypropyl oleic acid (CCHOA) as a dopant, and its anti-corrosion properties were evaluated by incorporation into epoxy resin coatings. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses confirmed that CCHOA-doped PANI produced a more uniform and compact microstructure with reduced agglomeration. The corrosion resistance and toughness of the epoxy coatings initially improved with increasing CCHOA content, but then slightly declined, which allowed us to determine the optimal doping level for PANI. The ideal concentration was found to be 0.5 mol/L in the epoxy resin matrix. Full article