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Study on the Adsorption Performance of Hydroxyapatite-Loaded Biochar for Cu
No full textHydroxyapatite-loaded biochar (HAP–biochar) composites were synthesized using corn straw biochar (CSB) and chicken manure biochar (CMB) to improve Cu²⁺ removal from aqueous solutions. Composites with varying biochar:HAP ratios were prepared and characterized by SEM, which confirmed uniform HAP dispersion and enhanced porosity. Systematic testing identified the composition corresponding to biochar:HAP = 3:1 (designated CSB-1.5 and CMB-1.5; HAP ≈ 25 wt%) as optimal. Under pH 5.0 and an adsorbent dose of 0.05 g, CSB-1.5 and CMB-1.5 achieved maximum Cu²⁺ capacities of 82.06 and 98.09 mg·g⁻¹, respectively. Kinetic and isotherm analyses indicated that adsorption followed a pseudo- second-order model (R² ≈ 0.99) and was dominated by chemisorption via ion exchange and surface complexation; Elovich fitting supported heterogeneous surface behavior. Compared to single-component HAP or pristine biochar, the optimized composites combine improved HAP dispersion, abundant functional groups, and robust pore networks, delivering high removal efficiency and material stability. These features make the optimized HAP–biochar composites promising, low-cost adsorbents for practical heavy-metal remediation
Research on the Optimization of Cemented Soil Mixing Pile Technology
No full textAs a core technology for soft soil foundation reinforcement, cement-soil mixing piles are widely used in road, municipal, and construction projects. However, existing processes still have shortcomings in adaptability to complex strata, construction parameter control, and quality stability, which restrict the improvement of project benefits. This study aims to solve problems such as poor mixing uniformity and frequent pile quality defects in practical projects, and systematically explores process optimization paths through a combination of theoretical analysis, laboratory tests, and on-site verification. First, it sorts out the cement-soil reinforcement mechanism and differences between wet and dry mixing methods, and identifies key issues in the construction process and quality control of existing processes
Research on Construction Technology for Shield Tunnelling with Small Curve Radius under Shallow Cover Conditions
No full textThis article takes the shield tunnelling project of the southern entrance of Line 7 of Changsha Metro as a practical background, focusing on extremely complex working conditions including shallow cover (with a minimum thickness of only 3.8m, equivalent to 0.62 times the shield diameter D), small curve radius (R only 250m), low strength rock strata (unconfined compressive strength ranging from 2.25 to 5.96MPa), and the cutting line reception process.The conventional shield tunneling method typically faces challenges in controlling surface settlement and increased risks of segment misalignment and deviational errors under extreme conditions such as shallow overburden and tight curvature radii. In this context, a systematic and in-depth study of the key technologies during the shield reception phase was conducted. Through optimized earth pressure balance control, synchronous grouting process, dynamic regulation of the articulated system, and the application of precise guidance technology, combined with numerical simulation and real-time monitoring methods. Ultimately, the surface settlement was controlled within 12.5mm, segment misalignment to ≤10.0mm, shield posture deviation within ±25mm, and reception portal seal leakage to ≤0.05L/min. These results provide valuable technical references for shield reception construction in shallow cover with small radii, and have significant guiding implications for similar projects
A large multi-agent system with noise both in position and control
No full textIn this work, we consider a multi-population system where the dynamics of each agent evolve according to a system of stochastic differential equations in a general functional setup, determined by the global state of the system. Each agent is associated with a probability measure, that assigns the label accounting for the population to which the agent belongs. We do not assume any prior knowledge of the label of a single agent, and we allow that it can change as a consequence of the interaction among the agents. Furthermore, the system is affected by noise both in the agent’s position and labels. First, we study the well-posedness of such a system and then a mean-field limit, as the number of agents diverges, is investigated together with the analysis of the properties of the limit distribution both with Eulerian and Lagrangian perspectives. As an application, we consider a large network of interacting neurons with random synaptic weights, introducing resets in the dynamics
Fast-rotating blue straggler stars in the globular cluster NGC 1851
No full textWe studied the rotational velocities of a sample of blue straggler stars (BSSs) and reference stars belonging to the Galactic globular cluster NGC 1851 using high-resolution spectra acquired with FLAMES-GIRAFFE at the ESO/VLT. After field decontamination based on radial velocities and proper motions, the final sample of member stars was composed of 15 BSSs and 45 reference stars populating the red giant and horizontal branches of the cluster. In agreement with previous findings, the rotation of the reference stars is negligible in general (lower than 15 km s−1). In contrast, the rotational velocity is high (up to ~150 km s−1) for a subsample of BSSs. We found 4 fast-rotating BSSs (defined as stars that spin faster than 40 km s−1), which corresponds to a percentage of 27 ± 14%. This result delineates a monotonically decreasing trend (instead of a step function) between the percentage of fast-spinning BSSs and the central concentration and density of the host cluster. This supports a scenario in which recent BSS formation preferentially occurs in low-density environments from the evolution of binary systems
Analysis of community development programs and corporate image in mining industry using multidimensional scaling
No full textThis study analyzes the implementation of Community Development Programs (PPM) by a mining company and its relationship with community perceptions of corporate image in Bedoyo Village, Ponjong District, Gunung Kidul Regency. Primary data were collected through questionnaires administered to 135 respondents using simple random sampling, while secondary data included company documents and Community Development (COMDEV) reports. Data were analyzed using descriptive methods and Multidimensional Scaling (MDS). Results indicated that community knowledge of PPM was limited (mean 3.09), while satisfaction (3.52) and corporate image (3.50) were rated good. MDS analysis yielded a stress value of 0.11013 and R Square of 95.8%, forming four perceptual clusters linking health, education, infrastructure, and economic programs to community welfare. In conclusion, community satisfaction with program benefits plays a more decisive role in shaping corporate image than knowledge alone
Coal characteristics of the eocene to pliocene epoch: A case study in the Berau Sub-basin, East Kalimantan, Indonesia
No full textA complex material, coal is primarily composed of carbon, hydrogen, oxygen, nitrogen, sulfur, and other minerals. The research area is located in the Berau Sub-basin, which is part of the Tarakan Basin. The oldest to youngest formations are Sembakung, Latih, Labanan, and Sinjin. From such formations, 20 coal samples were taken. The aim of this project is proximate analysis to identify the characteristics of coal in each formation and regression analysis to explore the correlation between total moisture, ash content, and calorific value. Each formation's vertical column drilling provided coal samples, and they were tested using proximate analysis to determine total moisture, ash, volatile matter, fixed carbon, and calorific value. The Sembakung Formation has 5.72% total moisture, 25.65% ash, 19.70% volatile matter, 53.75% fixed carbon, and 6069 kcal/kg calorific value. The Latih Formation averages 29.87% total moisture, 4.03% ash, 39.69% volatile matter, 37.89% fixed carbon, and 5406 kcal/kg calorific value. The Labanan Formation averages 42.07% total moisture, 3.33% ash, 43.23% volatile matter, 40.25% fixed carbon, and 5488 kcal/kg calorific value. The Sinjin Formation averages 47.95% water, 3.08% ash, 40.56% volatile matter, 39.12% fixed carbon, and 5405 kcal/kg calorific value
Farmer’s adaptation behavior and strategies under the climatic change’s impacts
No full textSerengeti district in Tanzania, a climate-vulnerable region, faces increasing risks to farmers' livelihoods and food security due to climate change. This study examines farmers' adaptive behaviors using the Adaptive Capacity Framework (ACF), which analyzes five key dimensions: assets, flexibility, learning, social organization, and agency. Through participatory methods, the research assesses both strengths and capacity gaps in local adaptation. One analytical tool was employed, Importance-Performance Analysis (IPA). IPA revealed significant gaps between the perceived importance and actual performance of critical services such as agricultural extension, access to credit, and timely weather information. These results highlight the need for climate adaptation approaches that align with community priorities and realities. The study concludes that enhancing farmers' adaptive capacity requires inclusive, multi-dimensional strategies supported by improved institutional frameworks and access to key resources. The proposed framework serves as both a diagnostic tool and a practical guide for community-centered climate resilience and planning
Statistical analysis of key indicators in district heating operations in northern China over the past five years
No full textThis study presents and applies a questionnaire-based systematic methodology for analysing the operational strategies and energy efficiency of district heating systems in northern China. By examining data from 144 heating companies covering approximately 42% of the urban heating area over five heating seasons (2017–2022), the study focuses on trends in key energy consumption indicators at both the heat source and network sides. The results indicate an overall decline in specific heat consumption on the heat source side, along with improved efficiency in both coal-fired and gas-fired boilers, albeit with notable regional disparities. On the network side, significant regional imbalances were observed in make-up water rates for both primary and secondary networks and in electricity consumption at heat exchange stations, highlighting acute infrastructure aging issues particularly in northeastern China
Research on the application of distributed photovoltaic-battery systems in commercial-office complexes: The impact of building hybrid characteristics on PVB systems
No full textThe feasibility of distributed photovoltaic battery (PVB) systems in buildings has been validated, demonstrating that the integration of renewable energy with energy storage is essential for achieving low- carbon operational goals in buildings. Prior research has illustrated that complementary electricity consumption between buildings can reduce storage capacity requirements. However, there are currently few studies that utilize real-world electricity consumption data from actual building complexes to comprehensively evaluate the performance and characteristics of PVB systems from perspectives such as building type composition, scale, and PV penetration rate. This study is based on year-round electricity load data from multiple real-world commercial and office buildings. The study examines how the mix of shopping malls and office buildings, as well as the load distribution ratio, influence the performance of PVB systems. The findings reveal that during non-working days, the electricity load complementarity between the two building types in commercial-office complexes enhances the matching performance of PVB systems, leading to greater economic benefits. Additionally, the electricity load ratio between office and commercial buildings, has a significant impact on the application of PVB systems. The conclusions and analyses from this study offer data support for demand response strategies aimed at efficiently utilizing renewable energy in commercial-office complexes