Search Results (1,755)

Deep-mining operations are increasingly challenged by severe thermal hazards, which have become a critical bottleneck for achieving safe, efficient, and sustainable mineral extraction. While research on deep-mine cooling and heat hazard mitigation has proliferated, the field lacks a systematic, critical review that explicitly examines these advances through the lens of sustainability science. To address this gap, this study conducted a comprehensive bibliometric analysis of 432 publications (1994–2024) retrieved from the Web of Science Core Collection. The methodology employs Bibliometrix, Vosviewer, and CiteSpace to map the intellectual landscape, research hotspots, and evolving frontiers of the field. The results reveal a clear three-stage development trajectory and identify China, the USA, South Africa, and Canada as leading contributors, with national research emphases on ventilation, energy conservation, and refrigeration, respectively. Crucially, keyword clustering and burst detection uncover a notable paradigm shift: the focus has moved from isolated cooling techniques toward integrated, multi-objective strategies—including geothermal energy co-exploitation, phase-change material applications, and system-level energy optimization—signaling a growing alignment with resource efficiency and low-carbon mining principles. However, a critical finding is that the literature remains predominantly techno-centric, overwhelmingly evaluating performance through operational energy savings while largely neglecting life-cycle environmental impacts, holistic sustainability assessment metrics, and the influence of policy drivers. This review thus not only provides a structured overview of the domain, but, more importantly, exposes these critical knowledge gaps. We argue that future research must pivot toward a multi-dimensional sustainability framework that integrates technical, economic, and environmental dimensions, thereby guiding the next generation of research toward truly sustainable deep-mining practices. Full article

The energy performance of a building reflects its typical energy use and is influenced by factors such as the building envelope (insulation and windows), system efficiency (particularly for heating, cooling, and domestic hot water), and the integration of renewable energy sources. Improving energy performance helps save energy, boost energy independence and security, lower energy costs, and reduce the need for grid investments. Standardizing energy performance assessments enables benchmarking and comparison of building efficiency, encouraging informed decision-making. In this context, the paper presents a knowledge discovery-driven intelligent decision-making system, designed, developed, and tested to identify the best strategies for prioritizing buildings in the envelope process. The system combines data mining techniques with statistical analysis to precisely rank and thoroughly evaluate low-energy-performance buildings and to develop scenario-based strategies for enveloping the buildings to achieve high energy efficiency (associated with nearly zero-energy buildings) under real-world conditions. Testing of the proposed intelligent decision-making system was conducted using a real building database of approximately 3900 records, uploaded from the Romanian central administration website. Under the highest-performance scenario of the envelope-priority strategy, which includes nearly zero-energy building standards, energy savings exceeded 50% across all categories: 51.70% for healthcare, 53.40% for residential, 60.11% for administrative and office buildings, and 69.92% for educational institutions. Overall, the average savings across all building types were 59.81% (644.86 GWh/year). Full article

This paper reviews recent advances in modular permanent magnet (PM) machines and their associated thermal management strategies. It begins by examining developments in conventional PM machines and highlighting their limitations, particularly in fault tolerance and manufacturability. To overcome these challenges, modular stator configurations have been extensively investigated over the past decade. The review discusses the key advantages of modular PM machines, including improved torque density, efficiency, operational reliability, and enhanced fault-tolerant capability, supported by findings from recent studies. The paper then presents a comprehensive review of state-of-the-art thermal management techniques for PM machines, emphasizing their importance in maintaining performance, reliability, and durability under increasingly high-power densities and thermal stresses. Both passive and active cooling approaches are considered, including air cooling, liquid cooling, heat pipes, oil-spray cooling, shaft cooling, and emerging ferrofluid-based cooling technologies. Advances in thermal modelling and coupled electromagnetic–thermal optimization are also highlighted as important enablers for improving machine performance and efficiency. Furthermore, the review explores the interaction between stator modularity and thermal management, with particular attention to how modular machine architectures affect heat generation, thermal paths, cooling integration, and overall thermal performance. Finally, the paper identifies key research challenges and outlines future opportunities for the development of high-performance, thermally robust PM machines for next-generation energy and transportation applications. Full article

The construction industry contributes significantly to global CO₂ emissions, primarily due to the production of ordinary Portland cement (OPC). As a sustainable alternative, geopolymer concrete, utilizing industrial by-products, such as ground granulated blast furnace slag (GGBFS) and fly ash (FA), has attracted increasing attention. However, studies on the post-fire behavior of high-strength slag–fly ash-based geopolymer concrete (HSSFGC) remain limited. In this study, two HSSFGC mixtures with FA contents of 10% and 30% were prepared and exposed to elevated temperatures of 100 °C, 300 °C, 450 °C, and 600 °C. After natural cooling, mass loss, ultrasonic pulse velocity (UPV), residual compressive strength, and microstructural evolution were investigated using XRD, FTIR, TGA, SEM, and EDS techniques. The results show that as temperature increases, mass loss and internal defects also increase, accompanied by deterioration of the interfacial transition zone (ITZ). At 100–300 °C, specimens with higher FA content exhibited improved residual compressive strength due to secondary geopolymerization of unreacted FA. However, above 300 °C, all specimens experienced significant strength degradation, with residual compressive strength at 600 °C reduced to 57% for FA-10 and 49% for FA-30 of their respective room-temperature values. This mix-specific difference, attributed to higher pore connectivity and more severe dehydroxylation in FA-30. These findings reveal the temperature-dependent degradation mechanisms of HSSFGC and provide a theoretical basis for post-fire assessment and sustainable engineering applications. Full article

Face milling of aluminum 7075 hybrid metal matrix composites with 10 wt.% TiO₂ and 3 wt.% graphite (HMMCs) are needed to improve performance and sustainability. This study focuses on optimizing the milling process for Al7075 HMMCs using the desirability approach and advanced multi-criteria decision-making (MCDM) methodologies, including the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and the Combined Distance-based Assessment (CODAS). Surface roughness (SR), cutting force (CF), carbon emissions (CE), and energy consumption (EC) were systematically evaluated and ranked using the L₁₈ Taguchi Orthogonal Array. Minimum Quantity Lubrication (MQL) and cryogenic CO₂ cooling techniques were used to achieve a superior surface finish and reduce friction at the tool-workpiece interface, thereby minimizing scratches and thermal damage. Desirability evaluation results showed the optimal machining conditions for milling of Al7075 (HMMCs) occurred at a cutting speed (V_c) of 200 m/min, a feed rate (f) of 0.02 mm/rev, and a depth of cut (a_p) of 0.3 mm, proving the potential of integrating MCDM tools with effective cooling strategies. The desirability method favored a balanced compromise, while entropy-weighted TOPSIS/CODAS emphasized energy and carbon-related responses. Improvements of 6% in cutting force, 7% in surface roughness, and a 7% reduction in energy consumption, along with 8% lower carbon emissions, were achieved, demonstrating the effectiveness of hybrid cooling strategies in promoting eco-friendly and resource-efficient processes. Full article

The climate crisis, housing precarity, and the loss of everyday architectural heritage are converging challenges in Mediterranean cities. This article investigates the adaptive reuse of early twentieth-century adobe refugee dwellings in Nea Ionia and Kaisariani, neighborhoods of Attica, Greece, as an integrated social, environmental, and cultural strategy. Historical documentation, urban-morphological analysis, field observations, building survey data, material assessment, and design-based microclimatic analysis were combined to evaluate compatible restoration and bioclimatic upgrades as alternatives to demolition and conventional energy retrofit practices, with the main aim of preserving an important part of Greek history and architecture. The study develops a replicable qualitative assessment framework that identifies how existing adobe envelopes, compact layouts, courtyards, thresholds, vegetated pergolas, and low-water evaporative cooling may support low-carbon housing reuse. The results clarify the current preservation conditions and reuse potential of the selected case-study fragments, showing that adobe dwellings can preserve embodied material value, retain thermal mass and hygroscopic regulation, and support social housing when repaired with compatible, low-impact techniques. The article argues that the reuse of adobe refugee dwellings can function as a distributed urban strategy for housing provision, heritage continuity, and microclimatic adaptation. Its main contribution is a transferable analytical framework for assessing overlooked earthen housing stocks in dense Mediterranean contexts. The study argues that adaptive reuse can serve simultaneously as a means of social housing, a mechanism for optimizing the microclimate, and a means of preserving the tangible and intangible heritage of Greek adobe buildings that have been standing for over 100 years. This position extends circular construction debates by prioritizing non-demolition and direct reuse while preserving an important period of history. Full article

This study proposes a multi-objective optimization strategy for the structural design of liquid-cooled channels in battery systems, aiming to identify liquid-cooled plate design schemes with better cooling performance and acceptable flow resistance. Optimal Latin hypercube sampling (OLHS) was combined with computational fluid dynamics (CFD) simulations to construct a CFD-generated dataset that includes the maximum temperature and system pressure drop. Then, modeFRONTIER was employed to integrate surrogate-model training, rapid prediction, and non-dominated sorting genetic algorithm II (NSGA-II) optimization, thereby obtaining the Pareto optimal set. The technique for order preference by similarity to ideal solution (TOPSIS) decision method was further introduced to determine the final optimal design. Results indicate that the optimized liquid-cooling system exhibits outstanding comprehensive performance in terms of balancing heat dissipation and flow resistance at a 5 C discharge rate. Remarkably, sensitivity analysis shows that inlet velocity is the dominant factor affecting the maximum battery temperature, with a correlation coefficient of −0.789. The maximum temperature of the battery module is effectively limited to 30.07 °C, while the flow pressure drop is only 799.58 Pa, achieving an excellent balance between heat dissipation efficiency and energy consumption. Full article

Energy consumption and resource utilization have become critical challenges in modern machining due to increasing manufacturing costs, stringent environmental regulations, and global carbon-reduction targets. While sustainable machining strategies such as dry machining, minimum quantity lubrication (MQL), and cryogenic cooling have been widely investigated, recent years have witnessed the rapid development of advanced assisted and hybrid machining processes aimed at further reducing energy demand and material waste. However, existing review studies largely focus on individual techniques or lubrication approaches, lacking a systematic perspective on the combined energy–resource saving mechanisms in advanced sustainable machining. This review presents a comprehensive and up-to-date analysis of energy consumption characteristics and resource-saving strategies in advanced sustainable machining processes. Particular attention is given to emerging and hybrid technologies, including ultrasonic-assisted machining, ultrasonic-assisted MQL, electrostatic MQL (eMQL), multi-nozzle MQL systems, nanofluid-based MQL, laser-assisted machining, vortex tube-assisted cooling, dry ice machining, and hybrid cryogenic–MQL strategies such as LN₂-MQL and CO₂-MQL. The review systematically discusses how these techniques influence energy flow, tool–workpiece interactions, lubrication efficiency, and thermal behavior during machining. Furthermore, this paper highlights the synergistic effects of combining multiple assistance methods, emphasizing their role in achieving simultaneous improvements in productivity, tool life, surface integrity, and sustainability performance. Energy-based metrics, resource efficiency indicators, and carbon emission considerations reported in the literature are critically evaluated to identify current limitations and inconsistencies. Finally, key research gaps and future directions are outlined, including the need for standardized sustainability assessment frameworks, data-driven energy optimization, and intelligent hybrid machining systems. This review aims to provide a valuable reference for researchers and practitioners seeking to design next-generation sustainable machining processes with enhanced energy efficiency and reduced environmental impact. Full article

Microwave (MW) ablation is a minimally invasive technique used to destroy pathological tissues through localized heating generated by a needle applicator. Internally cooled applicators using water circulation have long been the standard for high-power applications; however, water cooling introduces significant mechanical complexity. This work investigates the feasibility of a novel air-cooled coaxial thermal-ablation needle operating at 2.45 GHz up to 70 W. The system uses two concentric metal tubes—an outer 14 G stainless steel shaft (OD 2.1 mm) and an inner copper capillary (OD 1 mm, ID 0.7 mm)—serving simultaneously as the MW transmission line and cooling conduit, with dry air at room temperature (25 °C) flowing at 11 L/min under 5 bar input pressure. Experimental cooling efficiency tests demonstrated 78% efficiency for the shaft section in air and 32% for the section embedded in tissue. Electromagnetic and thermal simulations predicted ablation dimensions in a non-perfused liver of 35 mm short axis with ellipticity of 0.65 for the basic applicator, improving to 0.88 with an advanced PEEK-shaft design featuring a cancelling slot. A prototype was built and tested on exvivo bovine liver, achieving input matching better than −24 dB at 2.44 GHz and ablation dimensions (average of 5 tests) of 31 mm short axis and 45 mm long axis. Results confirm the feasibility of air cooling as a simpler, safer, and lower-cost alternative to water cooling for medium-power MW ablation. Full article

Buildings in hot–humid climates experience increasing thermal stress due to urban heat islands and climate change, leading to greater reliance on air conditioning. Passive cooling is therefore a crucial low-carbon strategy for maintaining thermal comfort. This paper reviews thermal comfort ranges and passive-cooling techniques across Köppen–Geiger hot–humid climate classes. A two-stage approach was adopted: thermal comfort data from 35 field studies were analyzed by climate class and ventilation mode, while more than 70 application studies were qualitatively reviewed to assess mechanisms, performance, and climate suitability. The results indicate that occupants in hot–humid areas exhibit broad thermal tolerance, particularly in naturally ventilated buildings, with neutral temperatures ranging from 19.5 °C in humid subtropical climates to 36.3 °C in tropical savanna climates. Natural ventilation is the most widely applicable passive-cooling strategy, but its effectiveness depends on integration with climate-responsive measures. Ventilation, combined with solar protection and courtyards, is most effective in Af and Am climates, whereas shading, solar chimneys, evaporative cooling, night ventilation, thermal mass, and phase-change materials provide greater benefits in Aw, Cfa, and Cwa climates. However, no single strategy is sufficient across all climates. The review provides climate-specific guidance for designing low-carbon, thermally resilient buildings in hot–humid regions. Full article

Liquid crystal physical gels (LCPGs) combine the anisotropic properties of liquid crystals with the structural stability of soft solids. In this work, MBBA-based LCPGs were prepared using chiral oxalamide gelators 1,6-bis((O-leucylmethanol)-N-yloxalamido)hexane (6-O-Me) and 1,9-bis((O-leucylmethanol)-N-yloxalamido)nonane (9-O-Me) and thoroughly characterized for their thermal, rheological, and electrorheological behaviours. Techniques included differential scanning calorimetry, oscillatory rheology, electrorheological testing, and advanced microscopy analysis. A custom microfluidic device was developed for in situ application of an electric field and optical assessment of its influence on microstructure formation. Both gels exhibited distinct gel-like behavior, with storage moduli consistently exceeding loss moduli and sustained network stability under both short- and long-term deformations. The gelators had minimal effect on the isotropic–nematic transition of MBBA but efficiently delayed crystallization, extending the stability window by −8 °C for 9-O-Me and −14 °C for 6-O-Me. When subjected to electric fields, the gel network weakened in the nematic phase, and the fiber assembly during cooling was altered, resulting in the formation of thicker, anisotropic fibers, consistent with microscopic observations. These results illustrate how the properties of LCPGs can be tuned through molecular design and external stimuli, expanding their potential for stimuli-responsive soft matter applications. Full article

Spray impingement cooling is a well-established heat removal technique employed across a wide range of industrial processes. A particularly significant cooling regime arises when the temperature of the cooled surface surpasses the Leidenfrost temperature of the spray. Developing an accurate numerical framework for this regime holds considerable potential for optimising industrial applications such as cryogenic machining and spray quenching. This paper presents a Eulerian–Lagrangian Conjugate Heat Transfer (CHT) model tailored for spray impingement under Leidenfrost conditions. Two heat transfer sub-models are incorporated to characterise droplet–solid thermal interaction: the first, developed by Breitenbach, is grounded in a theoretical analysis of the droplet impingement process, while the second, proposed by Deb, relies on a semi-empirical correlation. Both models were validated against an experimental correlation obtained from a literature study on orthogonal water spray impingement, yielding mean relative errors of 3.54% for the Deb model and 5.2% for the Breitenbach model across a broad range of operating conditions and surface temperatures. Full article

In the present study, the influence of microstructural morphology and dendritic refinement on the electrochemical corrosion behavior of directionally solidified aluminum-based structures (columnar and equiaxed) with Si contents between 6 and 12.6 wt. % was investigated in a 0.5% NaCl solution at room temperature. Corrosion resistance was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The directional solidification process was repeated for each of the alloy compositions at different cooling rates, yielding different secondary dendritic spacing values. The columnar-to-equiaxed transition (CET) was observed to occur when the temperature gradient in the melt decreased to values between −1.85 and 0.75 °C/cm. In addition, a small increase in the microhardness values was observed as a function of the Si content. The same applies to tensile strength values. The values of the polarization resistance are used as a basic criterion for the evaluation of the corrosion resistance of alloys. The columnar grain zone presents higher corrosion resistance than the equiaxed grain zone, despite presenting coarser dendritic spacing. This behavior contrasts with the commonly expected improvement in corrosion resistance associated with microstructural refinement and indicates that passive-layer stability and cathodic phase distribution play a dominant role in the electrochemical behavior. When the polarization resistance decreases with the increase in the distance from the base, the grain size and secondary dendritic arm spacings increase. In addition, when the polarization resistance increases, the critical temperature gradient decreases. This work allows us to conclude that the modification of thermal parameters in the solidification process can be used for the development of an optimized microstructure morphology and to optimize corrosion resistance in Al–Si alloys through control of dendritic spacing and passive film formation mechanisms. Full article

m-Aminostyrene (MAS) is a key molecular scaffold with an electron-donating amino group and a conjugating vinyl group, exhibiting significant potential in photonic materials and biological applications due to its rotamerism and photoinduced behavior. Despite its importance, a comprehensive, rotamer-resolved investigation of its vibronic and cationic spectroscopic properties is lacking. Here, we report a high-resolution study on the cis and trans rotamers of jet-cooled MAS using two-color resonant enhanced multi-photon ionization (2C-REMPI), UV-UV hole-burning (HB), and mass-analyzed threshold ionization (MATI) spectroscopies, combined with density functional theory (DFT) calculations. The HB technique unambiguously resolves the vibronic spectra of each rotamer, overcoming the limitations of previous one-color REMPI studies. The excitation energies (S₁ ← S₀) are determined to be 30,416 cm⁻¹ (cis) and 30,932 cm⁻¹ (trans). The MATI spectra yield precise adiabatic ionization energies (AIEs) of 61,569 cm⁻¹ (cis) and 61,274 cm⁻¹ (trans). A comprehensive assignment of vibrational modes in both the S₁ and D₀ states is provided, revealing distinct mode activities and frequency shifts between the two rotamers. A propensity for Δν = 0 upon ionization is observed, indicating high geometrical similarity between the S₁ and D₀ states. This work provides a crucial spectroscopic blueprint for understanding the electronic and vibrational structure of MAS rotamers, with implications for the design of functionalized styrene-based molecular systems. Full article

The rapid growth of electromobility and the increasing deployment of EV chargers emphasize the importance of pulse rectifiers with built-in power factor correction (PFC) filters. The new switching power devices offer higher converter switching frequencies, which enable a decrease in nominal values of passive components, such as inductors and capacitors, and their physical dimensions. Devices like CoolMOS and GaN enable operation with low switching power, but are usually constructed for lower drain-source voltage. From this point of view, the Vienna Rectifier is a prospective type of pulse rectifier with built-in PFC because of its reduced blocking-voltage requirements for the power transistors. Nevertheless, faster switching semiconductor devices with lower switching gate charge require more precise driving circuit tuning and setup. There are many scientific papers focused on the driving setup and techniques of the power transistors applied in H-bridge topologies. The purpose of this paper is to investigate the commutation loop and the related switching phenomena of the Vienna Rectifier topology. This paper evaluates the driver setup for a CoolMOS-based Vienna Rectifier with anti-serial connection of transistors forming a bidirectional switch. The switching transients are analyzed and simulated. Subsequently, the real driver settings are evaluated on the real prototype. Full article