Search Results (5,983)

Smart-building systems need reliable sensing, long-term storage, and remote control, but many studies mix up fast network response with slow physical changes in the building. We report measurements from an openHAB deployment at University Lab 1 and University Lab 2 in Greece over 19 months (April 2024–October 2025), with Z-Wave and ZigBee devices and Parquet exports for offline analysis. We treat sensing availability, Message Queuing Telemetry Transport (MQTT) command latency, and heating, ventilation, and air conditioning (HVAC) behavior as separate questions. In March–June 2024, raw record-level temperature field availability was 79.7% and 74.2% at University Lab 1 and University Lab 2, respectively, increasing to 99.7% and 98.5% after the <30 min linear field interpolation used in golden-dataset construction; assessable device-month cadence-normalized reading-count ratios were far lower (7.9% temperature and 13.0% humidity under the 300 s assumption at University Lab 1; humidity 7.8–26.0% across 180–600 s), reflecting heterogeneous archival participation rather than a fully populated expected-cadence denominator over the full archive span. In May–June 2024, 1247 MQTT commands yielded 1246 successful correlated responses; the archived application log contained no repeated correlation identifiers or duplicate response records (broker DUP flags are not archived); median, p90, and p99 latencies were 287 ms, 487 ms, and 1.66 s. These times describe the MQTT–edge-agent–openHAB path only, not physical device action. HVAC figures are illustrative; we do not infer settling times. The results show why availability metrics, archive denominators, and response-time boundaries must be defined separately in smart-building evaluations. Full article

Owing to its inherent flight safety, low takeoff and landing requirements, and favorable economic efficiency, the autogyro UAV, especially its electric and hybrid-electric variants, has become a core platform for low-altitude aviation missions such as transportation, inspection, and surveillance in plateau and offshore regions. However, the low air density and low Reynolds number conditions encountered in plateau regions can induce aerodynamic issues such as premature laminar flow separation, dynamic stall, and increased induced drag, which directly reduce payload capacity and endurance of small electric autogyro UAVs. In offshore environments, strong winds, turbulence, and gust disturbances intensify rotor–wake interactions, cause abrupt variations in aerodynamic loads, and reduce control margins, which severely restricts the mission reliability and flight safety of low-altitude unmanned platforms. These environmental effects collectively degrade rotor performance, including reduced aerodynamic efficiency and insufficient lift generation, and further amplify the energy constraint of electric/hybrid-electric propulsion systems. In response to bottlenecks that restrict the practical application of autogyro UAVs in extreme environments, this paper systematically reviews research progress on lift vector control for autogyro UAV rotors operating under such conditions. First, the typical aerodynamic problems encountered by autogyro UAVs in plateau and offshore environments are summarized, and their underlying physical mechanisms are analyzed from both system-level and local-flow perspectives, with a focus on how environmental factors affect the autorotation stability of unmanned platforms. Subsequently, the development of passive lift vector control technologies is reviewed, with an emphasis on the aerodynamic benefits of passive pitch mechanisms, vortex generators, and blade-tip winglets, as well as their engineering feasibility for small autogyro UAV blades. Active lift vector control technologies are then examined, including air-jet flow control, synthetic jets, and trailing-edge flaps, with discussions of their potential to delay flow separation and stall, enhance rotor aerodynamic efficiency, and an assessment of their adaptability to the energy and structural constraints of unmanned platforms. Finally, a lift vector control strategy suitable for autorotating rotors of autogyro UAVs is proposed, based on careful consideration of energy consumption, structural constraints, and control effectiveness. It provides a reference for aerodynamic optimization and flight control research on electric and hybrid-electric autogyro UAVs operating in extremely low-altitude environments. Full article

The global water crisis represents one of humanity’s most pressing challenges, with over 2 billion people lacking access to safely managed drinking water. This study presents the implementation and evaluation of an innovative air-conditioning condensate recovery system at Building F of the Faculty of Electrical and Electronic Engineering (FIEE), Universidad Veracruzana, Mexico. The system integrates twenty-six 24,000 BTU air-conditioning units across twelve classrooms and two laboratories, recovering approximately 520 L of condensate water daily. An initial physicochemical characterization of the recovered condensate was conducted through pH, electrical conductivity (EC), and total dissolved solids (TDS) measurements. In addition, the dried residue obtained after evaporation of the condensate was examined using semi-quantitative X-ray fluorescence (XRF) analysis. The XRF results describe the relative elemental composition of the dried residue and must not be interpreted as aqueous concentrations or as evidence of compliance with water-quality standards. The recovery system includes a nominal 0.5 µm polypropylene sediment cartridge, activated-carbon filtration, and a Crystolite^® treatment medium. Because paired measurements before and after treatment were not performed, the removal efficiencies of these components were not determined. The recovered water is subsequently stored and processed in a dual-tank configuration: a primary 3300 L storage system and a secondary 200 L tank used to prepare fertilizer-amended condensate for ornamental-plant irrigation. A fully water-soluble monopotassium phosphate fertilizer (MKP, 0 (–52–34) was incorporated at a gravimetric proportion of 1:10 (1 g MKP per 10 g recovered condensate water). Full article

Large-scale adiabatic compressed air energy storage (A-CAES) is essential for stabilizing power grids with high renewable energy penetration. However, the complex thermo-mechanical coupling in its multistage expansion and reheat systems poses significant challenges for dynamic control and operational safety. This study develops a coordinated control framework for the A-CAES energy release process. Based on control-oriented characteristic analysis revealing bidirectional power–temperature coupling mechanisms, a power setpoint feedforward decoupling strategy is proposed, reducing the stage-averaged temperature dynamic deviation of the four expander inlet temperatures from 7.74 K to 1.57 K during the upward power ramp. Furthermore, the gradient-based optimization (GBO) algorithm with the piecewise reset ITAE objective function is employed to optimize the PI controller parameters, yielding stage-averaged temperature dynamic deviations of 1.882 K and 2.249 K during AGC ramp-up and ramp-down, respectively, corresponding to reductions of 27% and 26% relative to empirical tuning. Numerical simulations of load rejection and three-phase short-circuit faults indicate the system’s dynamic stability and safety margins under the considered extreme conditions. This work provides model-based technical support for a 300 MW-class A-CAES demonstration project. Full article

This study addresses target-to-ROV relative localization in an unmanned surface platform-assisted UAV–ROV search-and-recovery system. Because the submerged ROV is not assumed to be visible from the air, the UAV observes the floating target and a GNSS-equipped ROV-associated surface buoy in the same image. The buoy position and target-to-buoy image displacement are combined to construct a world-frame target-position measurement, whose covariance accounts for buoy GNSS uncertainty and correlated image-projection errors. An upward-looking ROV imaging sonar provides range–bearing measurements. A delay-aware extended Kalman filter fuses the asynchronous observations using sea-state- and confidence-dependent covariance adaptation and normalized-innovation gating. ROV acoustic/inertial navigation uncertainty is propagated into the sonar measurement covariance and the reported relative-state covariance, avoiding duplication of the same navigation error in the aerial channel. The method is evaluated using a JONSWAP-based temporal disturbance model, Monte Carlo simulations, and single-factor and joint sea-state–occlusion–delay sensitivity tests. Under the nominal sea-state-5 condition, the proposed method achieves a mean ROV-frame relative RMSE of 0.992 m, compared with 1.083 m for ROV-only localization and 1.054 m for fixed-covariance fusion, with no run exceeding the 5 m divergence threshold. The results demonstrate improved relative-localization robustness within the simulated environment. Full article

A magnetic-levitation direct-drive oil-free scroll compressor (MLDD-OFSC) eliminates the anti-rotation mechanism to achieve oil-free operation. Still, its large-stroke planar motion introduces strong sensor–DOF coupling and air-gap-dependent stiffness variation that degrade fixed-gain PID performance. This paper proposes a control strategy integrating acceleration feedback linearization, gain-scheduled PID, and coordinate decoupling. An inverse electromagnetic force model is derived to compensate for the nonlinear force–air-gap relationship, linearizing the suspension dynamics. A phase-adaptive gain scheduling law is developed, where gains vary with trajectory phase via a cosine-based mapping. A homogeneous transformation matrix decouples raw sensor signals into independent X, Y, and yaw DOFs. Frequency-domain analysis at three air-gap positions confirms closed-loop stability. Simulations show that the proposed acceleration-linearized gain-scheduled PID (AL_GS_PID) outperforms traditional PID and fixed-gain AL_PID in tracking accuracy. Experiments demonstrate progressive improvement across four configurations—decentralized PID, decoupled PID, fixed-gain AL_PID, and AL_GS_PID—with the full scheme reducing peak errors to 0.043 mm in X and 0.04 mm in Y, corresponding to 74.7% and 33.3% reductions over decentralized PID. These results demonstrate that the proposed strategy effectively addresses coupling and stiffness variation in large-stroke maglev systems under no-load and light-load conditions. Full article

Airborne microplastics and nanoplastics (MNPs) are increasingly reported in indoor, outdoor, and occupational air, but their aerobiological significance remains incompletely defined. This narrative review proposes the aeroplastic exposome as a cautious, testable framework for evaluating airborne MNPs as interfaces among aerosol transport, biological and chemical loading, aeroallergen co-exposure, inhalation, respiratory deposition, clearance, and airway immune response. Evidence from environmental monitoring, indoor and occupational exposure studies, and human respiratory-sample and lung-tissue detection studies supports the occurrence of airborne MNPs, the plausibility of inhalation exposure, reported detection in human respiratory samples, and experimental hazard under selected conditions. However, evidence that airborne plastic particles routinely carry bioaerosols or aeroallergens remains insufficient or model-dependent. The aeroplastic exposome is therefore not proposed as a disease entity, validated exposure metric, or established explanation for asthma, chronic obstructive pulmonary disease, fibrosis, infection, or cancer. Instead, it is a framework for organizing testable questions about polymer identity, aerodynamic fraction, morphology, aging state, biological loading, co-exposure context, deposition, clearance, epithelial–immune responses, and host susceptibility. Priority research needs to include standardized airborne sampling, same-particle polymer–bioaerosol–allergen characterization, exposure-relevant aerosol systems, factorial co-exposure experiments, and prospective human studies with repeated personal exposure assessment. Full article

Indoor air pollution caused by volatile organic compounds (VOCs) is a major environmental and public health concern. Ethanol is a common indoor VOC released from cleaning products, disinfectants, and industrial activities. This study evaluated the capacity of Ficus elastica Roxb. to remove airborne ethanol under controlled chamber conditions. Response Surface Methodology was applied to optimise the effects of initial ethanol concentration, relative humidity, and exposure time on removal efficiency. The model predicted a maximum removal efficiency of 97.16%, which was experimentally validated with an average efficiency of 96.2%, confirming the model’s reliability. Analysis of variance identified exposure time as the most influential factor affecting ethanol removal. Desorption experiments showed only limited and transient ethanol re-emission, indicating that ethanol was not merely adsorbed but also partially metabolised by the plant. Scanning electron microscopy revealed structural changes in stomatal morphology after prolonged exposure. Biochemical analyses demonstrated increased total phenolic content, flavonoid content, and antioxidant capacity, whereas a moderate decline in total chlorophyll reflected physiological stress accompanied by enhanced defence responses, indicating adaptive tolerance to prolonged ethanol exposure. These findings demonstrate the potential of F. elastica as an effective and sustainable botanical biofiltration system for improving indoor air quality. Full article

Triethylenediamine (TEDA)-impregnated activated carbon (AC) is widely used in the air purification systems of nuclear power plants to retain gaseous radioactive species. Regeneration and reuse of spent AC may reduce radioactive waste management burdens, but the recovery of adsorption-relevant properties after treatment requires experimental evaluation. This study evaluated whether a single thermochemical treatment followed by TEDA re-impregnation could recover adsorption-relevant properties and CH₃I-capture functionality. Four AC states were comparatively characterized using N₂/CO₂ physisorption, elemental analysis, XPS, XRD, and TGA, with one determination per applicable sample condition. Thermochemical treatment restored approximately 95% of the BET surface area and micropore volume relative to fresh AC. Nitrogen-based TEDA-equivalent loadings were 5.96 wt% for the initially impregnated Sample 2 and 5.30 wt% for the re-impregnated Sample 4. In single-run CH₃I breakthrough tests under modified laboratory-scale conditions, the 5% breakthrough times were 3861 and 4949 min/g respectively. These results indicate first-cycle recovery of measurable CH₃I-capture functionality after thermochemical treatment and re-impregnation. However, the results do not constitute ASTM D3803 qualification, and further replicate, control, multi-cycle, and long-term validation is required before practical reuse can be assessed. Full article

This study investigates the influence of unsteady heat and mass transfer processes on the formation of gas composition and thermal conditions in a large cross-section (132 m²) blind-end chamber of a gypsum mine during the operation of diesel-powered mining equipment, including a front-end loader representing the LHD class and a dump truck. The modeled system considers a chamber where the LHD operates continuously, while the dump truck enters periodically to perform haulage cycles. Ventilation is provided from an adjacent panel haulage drift using a booster fan. Numerical simulations were carried out using ANSYS Fluent within the RANS framework, employing the realizable k-ε turbulence model, with consideration of thermal and gas convection. A dynamic mesh approach was applied to explicitly represent the motion of the dump truck. Both steady-state scenarios, corresponding to extreme equipment positions, and a fully transient case involving dump truck entry into the chamber followed by idling were analyzed. The results demonstrate that the movement of the dump truck generates a pronounced piston effect, which alters the jet flow structure and temporarily increases the supply of fresh air to the working face. It is shown that steady-state assumptions based on prolonged equipment presence near the face overestimate the total NO_x concentration within the large chamber and may not adequately reflect actual gas conditions over typical loading cycle durations. The analysis of unsteady processes using the dynamic mesh approach reveals significant inertia in contaminant accumulation within the chamber. This finding enables a more accurate estimation of the required airflow rate, reducing excessive safety margins compared to calculations based on the assumption of continuous equipment operation near the face. Full article

In air-suction maize precision seed metering, the power transmission and vacuum air supply are typically routed through separate, non-coaxial paths. This conventional layout leaves transmission components exposed to debris clogging, subjects the seed-metering disc to eccentric torque, and causes non-uniform suction pressure distribution, ultimately degrading seeding consistency. To address these issues, this study proposes a coaxial integrated design in which a servo motor offset from the seed-metering axis drives a hollow rotary support, and the drive output shares the same axis with the central air passage. Bench tests showed that motor-end feedback speed entered the final target-speed ±5% band within 8.0–36.6 ms, with maximum overshoot of 0.15–5.76%. Seed-disc pre-filling reduced the mean unseeded distance at start-up from 83.1 to 10.4 cm (87.5%, p < 0.001). Field verification at target spacings of 15 and 20 cm and measured speeds of 3.0–12.0 km/h produced quality-of-feed indices of 91.74–97.50%. The results demonstrate the functional implementation and operational feasibility of the proposed electric-drive system under the tested conditions. Full article

To address the technical bottleneck of balancing the wideband noise (100–800 Hz) and aerodynamic performance of multi-blade centrifugal fans in air conditioning indoor units, this paper proposes a “frequency-domain target-driven” parametric design method for micro-perforated silencers. This method began with the precise identification of the 1/3-octave band noise spectrum to determine two noise peak clusters—200–400 Hz and 700–800 Hz—as the target suppression frequency bands. Based on Ma Dayou’s micro-perforated plate theory, a reverse mapping chain of “target frequency range → resonance frequency → structural parameters (hole diameter, perforation rate, rear cavity depth)” was established to enable the quantitative calculation of the silencer’s geometric parameters. Addressing engineering constraints related to manufacturing precision, clogging prevention, and structural stiffness for the theoretically optimal aperture size (0.24 mm), the aperture was adjusted to 1.0 mm through iterative recalculation of the relationship between plate thickness and perforation rate, while maintaining the perforated plate constant k ≈ 1.40 to ensure that the theoretical sound absorption frequency band remained unchanged. Test results show that under semi-anechoic chamber conditions (background noise ≤ 10 dB(A)), the micro-perforated silencer maintains airflow and power without attenuation across all airflow rates; noise peaks in the 200–400 Hz and 700–800 Hz frequency bands are significantly suppressed, and the full-band spectrum tends toward flatness. The average total noise level was reduced by 1 dB(A), and the average peak sound pressure level was reduced by 4 dB(A); the reduction in peak levels was four times that of the total reduction, revealing that the noise reduction mechanism of this method is “frequency-selective resonant absorption” rather than “uniform attenuation across the entire frequency band.” This study provides a quantifiable and reproducible design process for micro-perforated silencers, offering methodological support and engineering references for the development of low-noise compact fan systems in household appliances. Full article

Connected, automated, shared, and electric (CASE) vehicle concepts are considered a promising approach for improving the sustainability of urban mobility by increasing vehicle utilization and reducing fleet size. While the energy consumption of conventional battery electric vehicles has been investigated extensively, the influence of fleet size, speed limits, and ambient temperature on the energy demand of CASE vehicle fleets has received little attention. This study presents a simulative consumption analysis of an all-electric CASE vehicle fleet based on the EDAG CityBot concept. A validated microscopic traffic simulation of the city center of Darmstadt, Germany, is coupled with a backward-facing powertrain model and detailed secondary consumer models to determine the total fleet energy consumption under varying operating conditions. The analysis considers fleet sizes between 20% and 100% of a reference fleet, together with a 17% fleet size scenario, which allows for the fulfillment of the urban mobility demand according to the vehicle system provider. Besides fleet size, three urban speed limit scenarios and five ambient temperature scenarios are evaluated. Among the investigated fleet size scenarios, the lowest mean fleet energy demand is observed at a fleet size of 20%, resulting from the opposing effects of increasing driving energy consumption and decreasing secondary consumer energy consumption. However, the difference between the 20% and 17% scenarios is not statistically significant. Furthermore, the study demonstrates that secondary consumers, particularly automated driving hardware and heating, ventilation and air conditioning systems, represent a major contribution to the total energy consumption of CASE vehicles and must therefore be considered in fleet-level energy analyses. Although an individual CASE vehicle exhibits higher average energy consumption than a conventional battery-electric vehicle, primarily due to its greater average weight and rolling resistance, an increase in utilization of more than 16% would be sufficient to offset this disadvantage. Full article

Rapid growth in artificial intelligence, machine learning, and high-performance computing has substantially increased data centre rack power densities, resulting in higher heat generation and more demanding cooling requirements. As water remains widely used in many cooling systems, understanding the relationship between cooling technologies and water consumption is essential for improving cooling efficiency and sustainability. This paper presents a survey of reported water usage effectiveness (WUE) across 83 data centre entries, providing a combined dataset that links WUE with heat-rejection categories. The reported data shows that 23 of these data centres exceed 0.4 L/kWh, which is a sustainability target specified by the Climate Neutral Data Centre Pact for new data centres in water-stressed regions using potable water. Dry facilities employing closed-loop liquid cooling require essentially no water, while evaporative systems typically report water usage effectiveness values up to 2.5 L/kWh. Reported WUE is a facility-level operational metric, set by the proportion of the IT heat load rejected by evaporation, which depends on the heat-rejection topology, ambient wet-bulb conditions, and operating set points. A higher server-side heat transfer coefficient permits a higher coolant supply temperature for a given chip temperature limit, widening the range of ambient conditions under which heat can be rejected without evaporative assistance. Server-side heat transfer is therefore an enabling condition for low WUE rather than a determinant of it. One-dimensional heat transfer models are developed to estimate heat transfer coefficients for different server-level cooling mechanisms widely used for cooling servers within data centres, including air cooling, single-phase immersion cooling, direct liquid cooling, and two-phase immersion cooling. Air cooling, with the lowest heat transfer coefficient, remains widely used in small-scale facilities, whereas direct liquid cooling and two-phase immersion cooling achieve coefficients up to three orders of magnitude higher and are increasingly deployed in high-density installations. These coefficients are used to derive an equivalent evaporative water demand, an upper-bound estimate of the water that would be evaporated in rejecting the heat each mechanism removes; it shares the units of reported WUE but describes thermal capability rather than facility water consumption. Full article

This study investigates the thermal, economic, and environmental performance of heat recovery ventilators (HRVs) in hot climates, which has not been thoroughly investigated because standards and applications to date have focused primarily on cold climates. Experimental testing was conducted at airflow rates of 200–350 m³/h and outdoor air temperatures of 30–45 °C, representing typical summer conditions. HRV thermal performance was evaluated by measuring airflow rates and temperatures and then determining the heat transfer rates between the two air streams. Effectiveness increased by 3.9% when the supply inlet temperature increased from 30 to 45 °C, but decreased by 9.3% when airflow increased from 200 to 350 m³/h. The overall heat transfer coefficient remained nearly constant with increasing supply temperature but increased by approximately 37% as airflow increased. The highest recovery efficiency ratio (RER), defined as the ratio of supply air pre-cooling capacity to HRV power consumption, was 26.6 Btu/W.hr at 300 m³/h and 45 °C. Economic analysis based on the reduction in ventilation cooling load yielded payback periods ranging from 2.7 to 13.3 years. Annual CO₂ emission reductions ranged from 151 to 776 kg/year per HRV unit, demonstrating the environmental benefits of HRV systems in hot climates. Full article