Prediction method of shield tunneling parameters in pebble stratum formed by weathered granite and quartzite

The pebble formation formed by weathered quartzite and granite is usually of high strength, strong permeability and poor self stability, which brings great difficulties to shield tunneling. It is necessary to adjust the tunneling parameters at any time to prevent the consequences of instability of the tunnel face, loss of stratum and surface settlement caused by the imbalance of the soil bin pressure. GA algorithm is embedded into PSO algorithm for parameter optimization, and grey theory is combined to establish the prediction model of soil chamber pressure based on grey least square support vector machine, which can solve the problem of difficult control of tunneling parameters in pebble stratum formed by weathered quartzite and granite. Research indicates: GA-PSO-GLSSVM chamber Earth pressure prediction model enhances the EPB chamber Earth pressure forecast accuracy in complicated strata by integrating the global search capability of the GA algorithm, the quick convergence of the PSO algorithm, and the anti-disturbance capability of the GM model. The GA-PSO-GLSSVM model has high goodness-of-fit and accuracy compared with other prediction models. This model can successfully prevent the a series of undesirable consequences such as destabilization of the palm surface, missing strata and settlement due to ground surface due to pressure imbalance in the soil chamber pressure. The research results can provide reference for EPB shield tunneling parameter control in Grade V surrounding rock

Treatment performance of small-scale vermifilter for domestic wastewater and its relationship to earthworm growth, reproduction and enzymatic activity

A vermifilter system packed with quartz sands and ceramsite was studied for domestic wastewater treatment. Results showed that good performance of vermifilter was achieved and removal rates were COD (47.3 – 64.7%), BOD5 (54.78 – 66.36%), SS (57.18 – 77.90%), TN (7.63 – 14.90%), and NH4-N (21.01 – 62.31%), respectively. An increase in hydraulic loading led to a decrease in treatment efficiency and adult earthworm abundance. In addition, activities of protease, alkaline phosphatase (ALP), and cellulase in earthworm body dropped, but superoxide dismutase (SOD) and catalase (CAT) increased with the hydraulic loading. Correlation analysis implied that larger earthworm (>0.3 g) abundance might play more positive role on wastewater treatment in vermifilter, compared to smaller worm. Earthworm enzymatic activities had significant correlation with treatment efficiency of COD and BOD5 by vermifilter. Thus an important relationship exists for earthworm population dynamics and enzymatic activities with COD and BOD5 removal rates of domestic wastewater by vermifilter.Key words: Vermifilter, wastewater, earthworm, population dynamics, enzymatic activity, treatment efficiency

IMECE2008-68236 A VARIANT MODULE DIVISION METHOD ON EXTENSION LOGIC FOR ASSEMBLY PROCESS

ABSTRACT The paper's focus is on the module division dynamically in the virtual assembly sequencing process for the product family, which will affect the module variant quality seriously. Most research merely divides the module on their functions, without paying the attention on which the module division is beneficial for the latter assembly process. Considered assembly relationships as a key constraint, a new variant module division measure based on Extension Logic is presented. Since the tolerances existing everywhere in the assembly process, the connection analysis is employed to build a constraint function on the tolerance. Physical constraints contain mating and combination constraints. After the dynamical position for different parts, the mating constraint is defined as the movement opposition between two mechanical elements including face alignment mating, shaft and hole mating or face against mating. Then the extension radiation model could be generated. According the average value of the relationship function to realize the module division, the product structure is divided into several sub-assemblies. As the main problem in virtual assembly is process collisions, a modified integer coded Particle Swarm Optimization Algorithm is used. Here every part is mapped to corresponding particle. The result is performed in the virtual environment of software DELMIA. At last the extension cluster method in this paper is compared with the direct dynamic cluster method. A case study is performed on virtual assembly of high power Light Emitting Diodes automatic sorting machine manufactured by a factory

Dissolved black nitrogen: an overlooked active nano-catalyst in the abiotic transformation of chlorophenols by sulfides in the subsurface water

Abstract The incomplete combustion of biomass and fossil fuels results in the formation of not only black carbon (BC) but also black nitrogen (BN), the dissolved fractions of which (i.e., DBC and DBN) are important components of dissolved organic matter pool. Relative to DBC, the activity and reactivity of DBN are much less understood. Here, we investigated the catalytic effect of DBN derived from N-enriched biomass in the abiotic transformation of chlorophenols by sulfides. The medium-temperature DBN (450 °C) exhibited 13–144% higher catalytic efficiency than other DBN samples and 9.3 times higher than its DBC counterpart. Both electron paramagnetic resonance spectra and fluorescent probe technique indicated that the attached sulfides contributed to the formation of reactive oxygen species (ROS) as the “primary” radicals by favoring electron transfer from DBN to chemisorbed oxygen, and then the generated ROS reacted with N-oxides in DBN to form reactive nitrogen species (RNS) as the “secondary” radicals. The contribution of RNS to the decay of 2-chlorophenol by DBN450 was up to 72%, much higher than that of ROS and non-radical mechanism. These findings suggest that the catalytic effect of DBN is distinct but no less significant than that of DBC to the abiotic transformation of micropollutants in water/soil systems. Graphical Abstrac

Thermal Polymerisation Synthesis of g-C₃N₄ for Photocatalytic Degradation of Rhodamine B Dye under Natural Sunlight

The photocatalytic performance of g-C3N4 materials prepared by different precursors for Rhodamine B (RhB) dye degradation was studied. Their crystal structure, morphologies, chemical compositions, functional groups, and optical and photoelectrochemical performances of prepared g-C3N4 were analysed and characterised using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV-Vis diffuse reflectance spectra, photoluminescence, and electrochemical workstations. The degradation of RhB dye in the presence of visible light and sunlight was utilised to assess the photocatalytic efficiency of the g-C3N4 photocatalyst. The results of the photocatalytic comparison experiment showed that the g-C3N4 photocatalyst prepared with urea as a precursor (UCN) has the best photocatalytic performance, achieving 99.61% removal in 40 min. In addition, the photocatalyst UCN can completely degrade 10 mg/L RhB dye within 20 min under sunlight, demonstrating its potential for practical applications under natural sunlight conditions. After four cycles, the degradation rate remains above 99%, demonstrating excellent stability and reusability. Due to its lower average pore number, larger BET-specific surface area and volume of pores, UCN provides more activity spaces and facilitates the adsorption of pollutant molecules, thereby enhancing photocatalytic activity. It was established through the active substance trapping studies that the main reactive species involved in the photocatalytic degradation process of RhB dye is •O2−. This study showed that g-C3N4 synthesised with urea as the precursor has better photocatalytic performance in the degradation of RhB dye