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Comparative Study of Rural Water Supply Models, Technologies, and Long-Term Management Mechanisms in Southeastern and Northwestern China
No full textChina's village and town drinking water systems face some challenges, including insufficient protection of water sources, outdated treatment processes and equipment, high leakage rate in distribution networks, serious risks of secondary pollution, and inadequate operation and management mechanisms. Enhancing the reliability of both water quantity and quality along the whole path from the source to the tap has therefore become an urgent task. This study systematically summarizes the selection and adaptation of water supply models in Chinese villages, and introduces key technologies and applications for supplying water from both conventional and non-conventional sources. Based on this, a set of long-term and targeted management mechanisms is constructed. By comparing the differences in water supply models between northwest and southeast China, the study summarizes experiences that are appropriate for different regions, providing scientific support and practical references for sustainable operation of rural safe drinking water projects
Fresh Properties and Early Strength of Diatomaceous Earth Based Geopolymer Pastes
No full textThe fresh properties of concrete are crucial for ensuring it is easy to produce and process while achieving optimal performance during and after hardening. This research investigates the fresh properties of geopolymer paste made from diatomaceous earth with molarities of 10M and 12M. The liquid-to-solid ratio of the paste is 0.6, using NaOH and Na2SiO3 alkali activators in a 1:1 ratio. The fresh properties tested include normal consistency, flow, density, setting time, and 3-day compressive strength. The normal consistency and flow tests show that the 10 M diatomaceous paste, with 25% water from the binder, achieves a flow diameter of 12 cm. Meanwhile, the 12 M paste, with 24% water, has a smaller flow diameter of 11.8 cm. Setting time data indicate that the 12 M paste hardens faster than the 10 M paste, reaching a higher level of hardness at 45 minutes. The 3-day compressive strength test reveals that the 10 M paste has a strength of 19.91 MPa, while the 12 M paste is slightly stronger at 20.02 MPa. The density of the 10 M paste is 1.235 g/cm3, while the 12 M paste has a higher density of 1.292 g/cm3. Overall, this research demonstrates that the molarity of the alkali solution significantly influences both the fresh and mechanical properties of the geopolymer paste, with the 12 M paste showing faster setting time, higher density, and greater compressive strength than the 10 M paste
Optimization of Enzymatic Biodiesel Production from Waste Cooking Oil Using Lipase: Process Modelling, Yield Enhancement, and Fuel Characterization
No full textThe energy crisis and environmental degradation caused by fossil fuels requires innovative sustainable alternatives. Biodiesel presents a viable solution through renewable feedstock conversion, yet traditional chemical transesterification encounters significant obstacles including soap formation, expensive purification processes, and free fatty acid (FFA) sensitivity. Waste cooking oil (WCO) remains underutilized primarily due to elevated FFA levels, making lipase-catalyzed transesterification an attractive eco-friendly approach. Response Surface Methodology with central composite design optimized key reaction parameters: lipase concentration, methanol-to-oil ratio, temperature, and duration. Statistical analysis revealed that individual lipase and methanol variations showed minimal significance; however, their combined interaction with temperature and time substantially affected biodiesel production. Maximum yield reached 85.6% at optimized conditions—10 wt.% lipase, 6:1 methanol-to-oil ratio, 60°C temperature, and 120-minute reaction time. Physicochemical testing validated product quality against ASTM D6751 and EN 14214 international standards. Measured properties included density at 872 kg/m3, kinematic viscosity of 4.5 mm2/s, flash point of 167°C, and copper strip corrosion rating of 1a. These findings demonstrate enzymatic catalysis as an effective green technology for converting WCO into high-quality biodiesel, simultaneously resolving waste disposal challenges while advancing renewable energy goals. The approach eliminates harsh chemical catalysts while maintaining commercial viability through acceptable conversion efficiency and product specifications
Blast Furnace Slag and Rice Husk Ash as sustainable materials in ternary blended concrete
No full textThis study investigated creating a sustainable M25 grade ternary blended concrete by replacing Ordinary Portland Cement (OPC) with 30% Blast Furnace Slag (BFS) and different amounts (0%, 5%, 10%, and 15%) of Rice Husk Ash (RHA). The fresh and hardened properties (slump, compressive strength (CS), density, and water absorption (WA)) of these concrete mixes are evaluated to determine the best blend. Overall the results indicate that the blend that contains 30% BFS and 10% RHA (SR2) is the most optimum: it had an acceptable slump of 78 mm that gave it a reasonable workability and worked effectively with curial material properties; it had the highest 28-day CS of 36.5 MPa which surpassed the control mix (32 MPa) due to whole material effects of pozzolanic and filler synergy; it had a hardened density of 2220 kg/m3, which is moderate, a reasonable 5.13% decrease from the control; and it had a water absorption of 2.25% which indicated a manageable increase in porosity, balanced with high gains in strength. The control mix achieved a higher density and overall workability with less WA. However, mixes with greater (10–15%) RHA developed a lower density, lower workability and greater WA. The 10% RHA mix indicated the appropriate compromise between promoting better mechanical performance with acceptable durability, confirming to be a structurally appropriate and environmentally sustainable concrete mixture
Influence of Outdoor Particulate Matter on Indoor Air Quality and Human Health Risks in Urban High-Rise Buildings
No full textUrban areas are largely exposed to the penetration of outdoor particulate matter (PM) indoors, degrading indoor air quality (IAQ) and causing significant human health risks. This work evaluates the impact of outdoor-generated PM on IAQ in a high-rise residential building, keeping windows open and closed under controlled conditions. Real-time monitoring was conducted to assess PM levels and vertical variations, while respiratory deposition dose (RDD) and health risk (HR) were estimated across four demographic groups. Morphological and chemical characterization of PM was also performed. Results reflected higher PM concentrations on upper floors than lower ones, with peaks during morning and evening traffic hours. Indoor PM levels decreased notably when windows were closed, proving as an effective mitigation measure. RDD was higher in men due to greater tidal volume, while HR was lowest for children aged 8-10 years, possibly due to their better immune system. PM particles exhibited spherical, clustered, and irregular morphologies, mainly containing Na, Al, Si, C, K, and Ca, with trace Barium from vehicular emissions. These findings indicate the need for effective urban air quality management and mitigation strategies to reduce indoor human exposure to traffic-related PM
Mapping the Policy-Economic-Technological Barriers in Construction & Demolition Waste: Cause–Effect Insights from a DEMATEL Analysis
No full textThe construction activities are done to improve the construction infrastructure, which impacts the social, economic, and environmental sustainability factors. The construction and demolition (C&D) waste management is a big issue that impacts the global economies due to rapid population growth, leading to construction waste generation, thereby affecting sustainable development goal achievement. The construction and demolition waste management have shown barriers to construction management, but very few researchers have explored the intersection through regulatory, financial, and infrastructural challenges, thereby constraining construction waste management initiatives. The research aims to bridge the knowledge gap on construction wastes, including the construction activities that need to be done to improve construction infrastructure, thereby impacting social, economic, and environmental sustainable developments. Adequate knowledge on construction wastes, construction activities to improve construction infrastructure, challenges, barriers to construction wastes, construction wastes, cause-effect diagram, decision-making trial evaluation laboratory, is also explored to obtain the construction wastes management barrier values to understand the results, thereby improving construction wastes management challenges
Nonsmooth data error estimates for exponential Runge–Kutta methods and applications to split exponential integrators
No full textWe derive rigorous error bounds for exponential Runge–Kutta discretizations of parabolic equations with nonsmooth initial data. Our analysis is carried out in the framework of abstract semilinear evolution equations, allowing for operators with non-dense domains. The results provide a foundation for establishing error estimates for nonsmooth data in prototypical problems such as the Allen-Cahn and Burgers equations. Furthermore, we apply these estimates to the analysis of split exponential integrators, yielding convergence results expressed explicitly in terms of the prescribed data
Accelerating Instrument Troubleshooting: An AI-Driven Approach to Eliminating O
No full textThe analysis of trace impurities in ultra-high purity oxygen (UPO) via GC-HDID is critically dependent on the O2 trap’s performance, where recurring breakthroughs pose a significant challenge. This paper presents an innovative troubleshooting framework that dramatically accelerates problem resolution by integrating AI, contrasting sharply with traditional, time-consuming methods. Conventional approaches involve laborious cycles of manual review, broad internet and literature searches, and multiple consultations before a testable solution can be proposed. Our novel workflow bypasses these inefficiencies. We fed instrument manuals and raw failure data from a ’T Instrument’ directly into an AI model (Gemini) for a “deep research” phase. However, initial AI outputs were too broad, identifying general-purpose purifiers rather than the specific, regenerable O2 trap in question, as many manufacturers do not disclose these proprietary details. Here, operator expertise became crucial. We iteratively tuned the AI’s research, refining our queries to focus on the specific context of regenerable, copper-based catalysts used for GC matrix removal. This expert-guided “deep research” successfully filtered out irrelevant information and led the AI to confirm a universal, underlying chemical principle—the copper redox reaction (2Cu+O2→2CuO; CuO+H2→Cu+H2O)—across different manufacturers’ traps. This pivotal, AI-generated insight, achieved through expert-led refinement, enabled a swift and accurate diagnosis when combined with operator experience. The root cause was not the regeneration reaction itself, but the incomplete removal of its H2O byproduct. The solution was therefore clear: significantly extend the total duration of the high-temperature helium purge across both the ’Heater’ and ’Standby’ phases. This optimized protocol completely eliminated breakthrough events. This AI-augmented methodology, where human expertise directs AI’s powerful analytical capabilities, represents a paradigm shift, saving considerable time on unfocused research and meetings, and presents a powerful, transferable framework for rapidly solving complex instrumentation challenges in gas analysis
Gas monitoring systems and calorimeters for hydrogen-containing natural gas applications
No full textThis study proposes semi-custom-made gas monitoring systems that combine our existing gas detection alarms and calorimeters to support decarbonization technologies. These systems require no catalytic combustion or separate columns, and the use of physical sensors eliminates the need for frequent cleaning or recalibration. Even with preprocessing, the unit remains compact and ensures straightforward maintenance. Application examples include monitoring hydrogen-containing natural gas, analyzing ammonia synthesis and decomposition, evaluating methanation, and assessing steel-mill by-product gases
First-passage resetting gas
No full textWe study a one-dimensional gas of N Brownian particles that diffuse independently but are simultaneously reset whenever any of them reaches a fixed threshold located at . For any , the system reaches a nonequilibrium stationary state (NESS) at long-times with strong long-range correlations. These correlations emerge purely from the dynamics, and not from built-in interactions. Despite being strongly correlated, the NESS has a solvable conditionally independent structure that allows for an exact computation of several physical observables, both global and local. These include the average density profile, the distribution of the position of the k-th ordered particles, the distribution of the gap between two consecutive particles and the full counting statistics, i.e., the distribution of the number of particles in a finite interval around the origin. This system is the first example of a conditionally independent structure where the conditioning distribution is explicitly dependent on N