Surface Elements Research Articles

Oxygen vacancy enabled mesoporous Mn–Co oxide material for high-performance formaldehyde sensor worked at room temperature

In recent years, the exploration of hazardous gases at room temperature (RT) has remained one of the key focuses in the research field of the semiconductor gas sensors. Herein, mesoporous manganese-cobalt (Mn–Co) oxides with abundant oxygen vacancies were synthesized by the combustion method assisted with the green reducing agent l-Ascorbic acid (LA). The synthesized Mn–Co oxides were performed by X-ray spectroscopy (XPS) and Raman spectrometer to research their chemical state of surface elements. The results manifested that the Mn–Co oxides with LA adding during preparation possessed abundant oxygen vacancies. Additionally, the gas sensitivity tests indicated that the Mn–Co oxides with a mole ratio of LA to metal elements (MCO-0.3L) exhibited best formaldehyde sensing properties compared to other prepared Mn–Co oxides in the concentration of 0.25–30 ppm at RT. Notably, its response to 5 ppm formaldehyde at RT was more than 7 times of that of the Mn–Co oxides prepared without LA adding (8.1 vs 1.1). The MCO-0.3L sensor has a limit of detection (LOD) as low as 5.2 ppb. It also showed good selectivity and reliability. The improved formaldehyde sensitivity of the Mn–Co oxides sensors is supposed as the synergistic action of the abundant oxygen vacancies and the mesoporous structure.

Metal-Organic Framework ZIF-67@NiCo-LDHs for Extraction of Polycyclic Aromatic Hydrocarbons of Water Sample

In this study, solid-phase microextraction (SPME) fiber adsorbents were coated with the metal-organic framework ZIF-67 and protected by layered double hydroxides (LDH) nanotubes. The findings unequivocally show that the extraction selectivity is dependent on the surface element composition of coatings produced from ZIF-67. The ZIF-67@NiCo-LDHs coating was chosen for the enrichment and detection of polycyclic aromatic hydrocarbons (PAH) in water samples due to its long-term stability and superior extraction selectivity. The calibration curves were dynamically linear and ranged from 0.00 to 100 g L−1 at the optimum circumstances, with correlation values (R 2) above 0.996–0.999. LOD values ranged from 0.07 to 0.5 ng L−1. Under ideal circumstances, the test compounds’’ repeatability for one fiber (n = 3), expressed as relative standard deviation (RSD%), ranged between 7.5 and 9.2%. Additionally, the synthetic fiber displayed 40 cycles of extraction and desorption and perfectly controlled development.

Wear suppression and interface properties of diamond tool in micro-milling of TC4 alloy under graphene nanofluid MQL environment

The sustainable micro-milling process of TC4 alloy has garnered significant attention in aerospace engineering. However, the poor machinability of TC4 alloy results in particularly severe tool wear. Tool wear directly affects the machining quality of the parts, and traditional cutting fluids of suppressing tool wear indirectly increase production costs and pollute the environment. Therefore, to suppress the negative effects caused by tool wear, this paper proposes the application of water-based graphene nanofluid in the micro-milling of TC4 alloy in diamond tools. Firstly, micro-milling experiments and molecular dynamics simulations were conducted in different environments, including dry and water-based graphene nanofluid environments. Finally, tool surface wear morphology, milling forces, surface elements and structural phase changes were compared in detail. The results show that tool wear, including adhesive wear, abrasive wear, and edge chipping, was suppressed by graphene nanofluids compared to dry conditions, thereby increasing tool life. The graphene nanofluid improved the contact state between the tool and workpiece interface, reducing the milling forces. In addition, molecular dynamics indicates that the catalytic effect of the transition elements in the workpiece on the diamond tool was also weakened, and the carbon atoms of graphene were used as a sacrificial source to balance the catalytic effect. Graphitization and diffuse wear of the diamond were suppressed. More importantly, the water-based graphene nanofluid not only improves the wear resistance of the tool, but the LCA results show its potential for sustainability. Consequently, it holds promise for advancing the sustainable processing of challenging materials.

An approach for measurement of the magnetic field near the surface of plasma-facing components in tokamak by laser induced breakdown spectroscopy based on Zeeman effect

Laser-induced breakdown spectroscopy (LIBS) has been demonstrated to diagnose the surface element distribution of plasma-facing components (PFCS) in fusion devices. However, the magnetic field intensity and polarity near the wall surface change frequently and cannot be measured in real time, which will affect the analytical accuracy of LIBS results. The determination of the strength and polarity direction of the magnetic field near the surface will be conducive to the quantitative analysis of LIBS and provide valuable information for the distribution of the magnetic field near the surface of PFCs. In this work, the effects of magnetic fields on the characteristics of laser-induced Mo plasma, such as the ablation depth and mass, the spatio-temporal evolution behavior of spectrum and the plasma parameters, were first systematically investigated. The different phenomenon of continuum radiation, Mo I line and Mo II line under the magnetic field were mutually verified by optical emission spectroscopy and fast plasma imaging methods. Meanwhile, an approach for measurement of the magnetic field intensity and polarity near the surface of PFCS by LIBS method has been proposed and investigated. When the magnetic field polarity is changed, the spatial distribution profile of Mo spectrum will drift in the opposite direction affected by of the Lorentz force, which realizes the measurement of magnetic field polarity. Moreover, the splitting distance of Mo I line caused by Zeeman effect with the variable magnetic fields were preliminarily calculated. The experimental values of splitting distance agree well with the theoretical values that calculated by the known magnetic field strength. These results confirm the feasibility of measuring the magnetic field intensity and polarity of PFCs surface by LIBS approach.

Using Smartphones as a Measurement Platform in Geoscience Applications

Most modern smartphones come with a variety of sensors. Among them are the gyroscope, accelerometer, magnetometer, GNSS (Global Navigation Satellite Systems) receiver, and from 2020, most modern devices are also coupled with a Lidar (Light Detection and Ranging) sensor. These specific sensors allow to acquire data that enables the location and spatial orientation of the smartphone in relation to other objects, and also measure them. For this, it is important to understand how the principle of operation of these sensors occurs, as well as the respective raw data obtained and how to use these data from the sensors to get measurements of the elements of the physical surface of the Earth. This article aims to present a state of the art about the working principle of these sensors and presents the raw data from them. In addition, this article seeks to present an initial test on the quality of the orientation sensor, based on the comparison between the data obtained from this sensor and a total station with high angular precision (1 second). It was noted the occurrence of a systematic error in the observations of the horizontal directions, and an average discrepancy of 5.20° between the observations of the vertical angle. The use of sensors attached to smartphones can support in several activities of geoscience application, such as carrying out a prior survey of a given area of study, aiming to do a pre-analysis of geodetic networks, to carry out measurements of angles and distances for applications in terrain measurements, or even to assist the Geographic Information System (GIS) development.

Construction Method for a Three-Dimensional Tunnel General Monomer Model Based on Parallel Pathfinding

Existing approaches for the 3D modeling of tunnels suffer from several problems, such as highly difficult data acquisition, redundancy of model data, large computational burden, and the inability of the resulting models to be monolithic. Therefore, solutions to the tunnel network modeling problem for complex structures need to be proposed and elaborated in detail. In this paper, a construction method for a three-dimensional tunnel general monomer model based on parallel pathfinding is proposed. Widely used tunnel CAD drawings are analyzed and read, a disordered arc ensemble intersection trend decision method is developed, and an automatic path extraction solution algorithm for unidirectional modeling of tunnel centerlines is constructed. By constructing and splicing the surface elements of the 3D model, a monomeric 3D tunnel model representing the complex network structure is finally obtained. Moreover, the modeling of shafts is realized based on the monomer model, allowing for the three-dimensional topological relationships between different sub-levels of the tunnel and the ground to be established. The automatic modeling method proposed in this paper is applied to the digital twin platform of a filling project in a mining area in Gansu province, China. The experimental results demonstrate that the 3D tunnel models constructed in this way have a smaller data volume, higher modeling accuracy, and more stable growth of modeling speed.

Comparative analysis of an anchored retaining wall system in a deep foundation excavation: A case study of Sivas Cultural Center Building in Türkiye

Modeling the surface element and support system in deep excavation pits and investigating the deformation mechanism is an important issue. In this study, alternative solution methods for an anchored bored pile model are compared and discussed, and it is aimed to contribute to the studies to be carried out in the deep excavation area. A numerical analysis of retaining wall design is examined in the case of the Sivas cultural center building's deep excavation using Plaxis 2D and GGU-Retain software. Measured field data and simulated results are discussed. As a result, the bending moment and lateral deformation reach a maximum when the foundation pit is excavated to the bottom. It can be said that the lateral deformation value found with Plaxis 2D is within the allowable limits, closer to the field data, and provides sufficient quality. The research results will provide theoretical and practical knowledge for designing and constructing similar deep excavation pits for the optimal strategy.

Spatio-temporal variation and hazard assessment of potentially toxic metal element contamination in sediments and water before and after a water-level fluctuation cycle in the Three Gorges Reservoir, Wanzhou, China.

Previous investigations on heavy metals in the water-sediment compartment focused on their spatial distribution, and the influence of sediment pH and organic matter (OM) on metal environmental occurrences. However, there are limited studies on the effects of physicochemical properties on the migration and transformation of heavy metals in the water-sediment compartments. This study investigated the relationship between the physicochemical properties of sediments and the distribution and chemical speciation of heavy metals, and the potential environmental risk of heavy metals in water and sediment using Risk Assessment Code (RAC) values and the Tessier five-step extraction method. Adsorption and desorption experiments showed that the sediment had weak adsorption and the strongest desorption capacity for Cd. Results of the pH, OM, surface element content, and X-ray diffraction (XRD) patterns suggested that cadmium (Cd) was more likely to partition into the water phase from the sediment during the flooding and water storage periods. When pH was 7-8 and OM content was 3.6-5.9%, the sediment-water distribution coefficient of Cd was low due to its large ionic radius, and the surface adsorption sites were saturated by other elements. These studies can provide a theoretical basis for the management and pollution control of the Three Gorges Reservoir.

Improving the anticorrosion property of outdoor fitness equipment via a novel Ti/Zr/Mo composite conversion coating

In recent years, a large number of outdoor fitness equipment have been newly built in China. In order to improve the anticorrosion property of outdoor fitness equipment, a new type of Ti/Zr/Mo conversion coating (TiZrMoCC) has been prepared on its surface. The surface morphology, element distribution, phase composition, and anticorrosion property were systematically measured, and the relationships between them were established. The results show that the optimal conversion temperature and time were 30 °C and 20 min, respectively. Under the optimal conversion parameters, the surface morphology of the TiZrMoCC is relatively flat and dense, and its phase compositions mainly consisted of TiO2, ZrO2, MoO3, Mo2O5 and Fe2O3, as well as a small quantity of Na3FeF6 and ZrF4. The TiZrMoCC could significantly reduce corrosion rate with the lower i corr , which is also confirmed by EIS results. The ACR of the TiZrMoCC decreased by nearly 63.5% compared to the Q235 matrix, and it has positive significance for protecting outdoor fitness equipment.

Effect of mixing ratios of SiO[formula omitted] nanoparticles synthesized from metakaolin on the physicochemical properties of ZnO/SiO[formula omitted] nanocomposites

Nanomaterials have distinguished themselves as an outstanding class of materials due to their unique physical and chemical characteristics compared to bulk materials. The physicochemical properties of nanomaterials can be improved by forming nanocomposites and manipulating different nanoparticles by varying their mixing ratios. In this study, ZnO and SiO2 nanoparticles and ZnO/SiO2 nanocomposites were produced using a sol–gel method based on the variation of mixing ratios (1:1, 1:2 and 2:1). The monometallic oxide nanoparticles (ZnO, SiO2) and the corresponding nanocomposites (ZnO/SiO2) were characterized using HRSEM, EDX, XRD, FTIR, BET and XPS. Regardless of the mixing ratio of ZnO and SiO2 nanoparticles used, the HRSEM pictures demonstrated a morphological change from the irregular and spherical forms produced for SiO2 and ZnO nanoparticles to rod-like shapes for the ZnO/SiO2 nanocomposite. The quartz phase of SiO2 nanoparticles, with a crystallite size of 43.67 nm, and the hexagonal wurtzite phase of ZnO nanoparticles, with a crystallite size of 31.52 nm, were both synthesized, as revealed by the XRD results. As opposed to this, the XRD patterns of the ZnO/SiO2 nanocomposites synthesized with 1:1, 1:2 and 2:1 mixing ratios showed a mixture of α-quartz (SiO2) and hexagonal wurtzite (ZnO) with crystallite sizes of 21.24, 29.56 and 15.36 nm, respectively. The EDS results confirmed the existence of Zn and O for ZnO; Si and O for SiO2 nanoparticles and Zn, Si and O in the prepared ZnO/SiO2 nanocomposite, irrespective of the mixing ratios. The XPS results showed the existence of Zn in the +1 oxidation state in ZnO/SiO2 compared to single ZnO with the Zn2+ valence. The BET surface area indicates that the ZnO/SiO2 nanocomposites had a higher surface area (1:1 (39.042 m2/g), 1:2 (55.602 m2/g) and 2:1 (82.243 m2/g)), irrespective of the mixing ratios, compared to the surface area for the ZnO (8.620 m2/g) and SiO2(0.386 m2/g) nanoparticles. The mixing ratio of the ZnO and SiO2 nanoparticles influenced the crystallite sizes, surface elements oxidation states and morphology of the ZnO/SiO2 nanocomposite formed and the optima mixing ratio for the formation of ZnO/SiO2 nanocomposite was found to be 2:1 of ZnO:SiO2 nanoparticles.

Investigation on the surface reactions of Mg–Al alloy/Teflon/Viton in O2

ABSTRACT A comprehensive study on the surface morphologies and element distributions of Mg–Al alloy particles and Mg–Al alloy/Teflon/Viton composite (MATV) during oxidation was conducted via scanning electronic microscopy and energy-dispersive X-ray spectroscopy. The formations of the reaction products of MATV were further analyzed via X-ray diffraction. By the temperature of 600°C, a fluorination reaction between Teflon and the alloy underwent on the alloy surface, involving the reaction of the αMg prime phase at lower temperature. A MgF2–AlFx shell surrounding the alloy particle was also generated simultaneously. This shell could elevate the oxidation temperature from the melting point of the alloy to 600~859°C. Furthermore, this shell could also severely decrease the oxidation rate of the exceeded alloy with O2. As the slower oxidation of the homogeneous liquid alloy began at higher temperature, a different mechanistic reaction from that of the pure alloy underwent. MgO particles rather than MgO ridges on the pure alloy surface were generated.

Quantifying interfacial interactions for improved membrane antifouling: A novel approach using triangulation and surface element integration method

To gain a thorough understanding of interfacial behaviors such as adhesion and flocculation controlling membrane fouling, it is necessary to simulate the actual membrane surface morphology and quantify interfacial interactions. In this work, a new method integrating the rough membrane morphology reconstruction technology (atomic force microscopy (AFM) combining with triangulation technique), the surface element integration (SEI) method, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the compound Simpson's approach, and the computer programming was proposed. This new method can exactly mimic the real membrane surface in terms of roughness and shape, breaking the limitation of previous fractal theory and Gaussian method where the simulated membrane surface is only statistically similar to the real rough surface, thus achieving a precise description of the interfacial interactions between sludge foulants and the real membrane surface. This method was then applied to assess the antifouling propensity of a polyvinylidene fluoride (PVDF) membrane modified with Ni-ZnO particles (NZPs). The simulated results showed that the interfacial interactions between sludge foulants in a membrane bioreactor (MBR) and the modified PVDF-NZPs membrane transformed from an attractive force to a repulsive force. The phenomenon confirmed the significant antifouling propensity of the PVDF-NZPs membrane, which is highly consistent with the experimental findings and the interfacial interactions described in previous literature, suggesting the high feasibility and reliability of the proposed method. Meanwhile, the original programming code of the quantification was also developed, which further facilitates the widespread use of this method and enhances the value of this work.

Investigation of Optical Properties and Activity of Wheat Stripe Rust Urediospores

Stripe rust is one of the most common diseases challenging the safe production of wheat. Rapid identification and analysis of urediospores, responsible for disease transmission, are the key to preventing and controlling stripe rust. The current spore detection is time-consuming and requires auxiliary equipment, but many optical detection methods and sensors with high efficiency, sensitivity, and detection ability have been developed and widely used. Thus, the investigation of optical parameters is the prerequisite for optical sensitive detection and is detailed in this study. Firstly, the microscopic images and surface elements of wheat stripe rust urediospores were obtained using a high-resolution electron microscope and an energy spectrum analyzer. The reflectivity and absorptivity spectra in the near-infrared band of active/inactivate urediospores were measured. Further, the optical parameters, such as reflection phase shift, complex refractive index, and dielectric constant, of the urediospores were analyzed based on electromagnetic theory and Kramers–Kronig relation. The results revealed that the urediospores have a strong tolerance to near-infrared light, and the real part of the complex refractive index n was between 1.0 and 1.4. These observations indicate that whether the spores are active or not has little effect on the real part and dielectric constant of the complex refractive index but has a significant impact on the imaginary part and extinction coefficient of the complex refractive index, and the corresponding relationship between the optical properties of urediospores and biological components was established. These findings were verified with HPLC-MS and Near-Infrared Spectroscopy Analysis Technology and lay a theoretical foundation for detecting urediospores of wheat stripe rust by using optical sensors. The study provides a reference for the analysis of optical characteristics of other biological samples.

THE VAULTING SYSTEM OF THE PALATINE CHAPEL: THE AACHEN CATHEDRAL WORLD HERITAGE SITE DOCUMENTATION PROJECT

Abstract. As part of a comprehensive survey and modelling project involving the Aachen Cathedral, this paper focuses on its oldest part, the Palatine Chapel, a domed octagonal hall supported by eight piers and enveloped by a sixteen-sided outer wall. Working on the data collected during an extensive 3D capturing campaign conducted between 2022 and 2023, this paper will focus on the conic vaults covering the ambulacrum of the 1st floor that represent quite a peculiar architectural and structural solution considering the VIII/IX century building know-how. In this framework, the Chapel's 3D point cloud has been analysed to extract the main 2D generative elements of the conic surfaces and then construct the corresponding 3D geometric models. These outputs have been compared against the captured point cloud to assess the differences between the actual vault data and the reconstructed ideal conic shapes. Finally, the method used to unfold the vaults' surfaces and create high-resolution ortho-images has been displayed.

Calculation method for determining the heat loss of the air environment when opening the passenger vehicle cabin doors

BACKGROUND: The microclimate in the bus cabin is of great importance in terms of both safety and comfort. The main parameters of the microclimate are temperature, humidity, dustiness and gassiness of the air, air exchange, the temperature of the elements of the interior surfaces and thermal radiation. AIMS: The article presents the results of calculating the heat loss in the air environment of the bus cabin using a mathematical model and experimental method. METHODS: The influence of different features of vehicle interior and exterior topology on the heat losses through the doors was estimated. The estimation of heat losses was performed using the ANSYS Fluent software package. The final result is to obtain the heat loss characteristics as a time-domain function. A field experiment was carried out to verify the obtained results. RESULTS: A set of numerical values and graphic characteristics giving an idea of the heat losses through the open doors of the bus cabin are presented. CONCLUSIONS: Due to the developed calculation method of determining the heat losses of the air environment, numerical values and graphical characteristics of the amount and intensity of time-dependent heat losses were obtained. The obtained results were verified experimentally. The study showed that the simulation in ANSYS Fluent and the field experiment have a discrepancy due to high values of the time constant of temperature sensors. In order to obtain the most accurate results, it is necessary to carry out the experiment with a time interval greater than the time constant.

PHYSICOCHEMICAL PROPERTIES ANALYSIS OF LOCAL CERAMICS WITH ACTIVATED CARBON ADDITIVE BASED ON RUBBER FRUIT SHELLS AS THERMAL INSULATORS

Many building materials that function as insulators to maintain indoor temperature stability during hot weather have been developed. One of them is porous ceramics applied to building walls as heat absorbers. Research related to the manufacture of porous ceramics began to emerge to find the optimal composition when applied as an insulator that can absorb heat well. In general, porous ceramics use activated carbon as a pore agent. Activated carbon can be obtained by carbonating agricultural wastes such as coconut shells, hazelnut shells, rubber fruit shells, rice husks, and cocoa shells. Research continues to develop in finding the best-activated carbon base material according to the required material characteristics. Researchers will take advantage of the abundant potential of local natural resources. The method used to make porous ceramics is to mix clay and activated carbon with a clay-carbon composition ratio of 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50. The sample is made by mixing the two materials and then printed by dry pressing method with a load of 5 tons held for 10 minutes. After the sample is dried at room temperature, it is sintered at 900oC with a holding time of 3 hours. Next, the sample is characterized by determining density, porosity, and water absorption and then tested for thermal properties. After that, the surface morphology and elements in the sample are seen. The optimum composition of clay-carbon mixture is 70:30 grams. Ceramics using activated carbon from rubber fruit shells are suitable as building construction materials as heat insulators because they can absorb heat up to 500oC.

Failure analysis of three-way catalysts through comprehensive characterization and understanding the role of pretreatment

Currently, most of the studies on waste three-way catalysts (TWCs) have focused on the extraction of platinum group metals (PGMs), with less characterization and analysis of their properties. This can lead to an incomplete understanding of the physicochemical properties and causes of failure of waste TWCs, which in turn affects the recovery of PGMs. This paper conducted various characterization analyses on waste TWCs, including their chemical composition, particle size, surface elements, microscopic morphology, specific surface area, and thermal stability. The PGMs content in the waste TWCs is 1468 g/t, and the total content of rare earth elements is about 1.58%, which has high recovery value. The analysis identified several reasons for TWC failure: the presence of S and P elements caused sulfidation and phosphorylation poisoning of PGMs; PGMs were also partially oxidized to PtO2, PdO2 and Rh2O3; in addition, sintering and agglomeration of waste TWC powder, encapsulation of PGMs in the substrate, reduction of specific surface area and total pore volume, and adsorption of accumulated carbon were also considered as causes of failure. The physicochemical properties of waste TWCs are extremely important for the selection of the PGM extraction process among them. Therefore, the effects of several pretreatment methods on the leaching efficiency of PGM were investigated. The results showed that grinding reduced the leaching rate of PGMs, and HCOOH reduction and NaHSO4 calcination pretreatment could improve the leaching rate of Pt and Rh, respectively; while the Li2CO3 calcination pretreatment could result in 70.87% leaching of Pt directly in HCl. The feasibility of extracting PGMs from waste TWCs using a Li2CO3 calcination pretreatment followed by direct HCl leaching was validated.

The distribution and enrichment of trace elements in surface and core sediments from the Changjiang River Estuary, China: Evidence for anthropogenic inputs and enhanced availability of rare earth elements (REE)

Huge amount of trace metals emitted through manmade activities are carried by the Changjiang River into the East China Sea. Most of them deposit in the Changjiang River Estuary and threaten the regional aquatic environment. In this study, major and trace elements of 34 archive surface sediments and two cores are examined. Sequential extraction procedures were also performed on surface sediments from 12 sites. We found that Tl, Tm, Er show distinct accumulation in surface sediments in the order of Tm > Tl > Er. Particularly, abnormally elevated HREE are observed mainly in those sites near the mouth of the estuary. Most elements exhibit an obvious reduction in the upper 30 cm of core B8, reflecting a decrease of sediment discharge from Changjiang River runoff. The increase of some trace elements recorded in the upper 20 cm of core C3 demonstrates a distinct local anthropogenic input in recent years.

Variations in the morphological phosphorus in a full‐scale A2O + MBR process with heavy chemical P removal addition dosing

AbstractThe removal of biological phosphorus (P) removal along with chemical P removal additions is significantly important role in removing P at full‐scale wastewater treatment plants (WWTPs). Few research groups have recently reported the use of P forms in these WWTPs. The current study mainly presents the varied forms of morphological phosphorus and the fate of chemical P removal agents in a full‐scale WWTP that has adopted the A2O + MBR process. With time, the TP concentration in the liquid phase and the solid phase reaches the minimum (0.27 mg/L) and maximum values (1.75 mg/g), respectively. At this point, the TP concentration at the end of the aerobic and membrane pool becomes nearly constant. This indicates the complete removal of effluent TP from in the system. The heavy chemical P removal and addition dosing result in Al–P being the predominant P form in the solid phase. The fate of the chemical P removal and agents was determined by investigating the valences of the surface elements in freeze‐dried MLSS at the membrane pool.

A Novel Numerical Method for Geothermal Reservoirs Embedded with Fracture Networks and Parameter Optimization for Power Generation

Geothermal recovery involves a coupled thermo-hydro-mechanical (THM) process in fractured rocks. A fluid transient equilibrium equation, considering thermal conduction, convection, and heat exchange, is established. The evolution of the reservoir permeability and the variance in the fracture aperture due to a change in the stress field are derived simultaneously. THM coupling is accomplished through iterative hydromechanical and thermo-hydro processes. To overcome the difficulty of geometric discretization, a three-dimensional THM coupler model embedded with discrete fracture networks, using a zero-thickness surface and line elements to simulate fractures and injection/production wells, is established to evaluate the geothermal production. The reliability of the method is verified by a case study. Then, this method is applied to evaluate the influence of the geometric topological characteristics of fracture networks and the fracture aperture on the reservoir temperature evolution and heat extraction effectiveness. The results show that the power generation efficiency and geothermal depletion rate are significantly affected by the injection–production pressure. Injection wells and production wells with pressures higher than the initial fluid pressure in the fractures can be used to significantly increase power generation, but the consumption of geothermal energy and loss of efficiency are significant and rapid. To achieve better benefits for the geothermal recovery system, an optimization algorithm based on simultaneous perturbation stochastic approximation (SPSA) is proposed; it takes the power generation efficiency as the objective function, and the corresponding program is developed using MATLAB to optimize the position and pressure values for each production well. The results show that the heat transfer for the entire EGS reservoir becomes more uniform after optimization, and the heat transfer efficiency is greatly improved.