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The evolution characteristics and the extent of the plastic zone in rock mass can reflect the failure characteristics and destruction degree of a hydraulic tunnel. In this research, we derived the equation of a plastic zone range based on a gateway-like structure high-temperature tunnel through a theoretical analysis. On-site monitoring and discrete element model simulation were combined to analyze the temperature field law and plastic zone evolution characteristics of the jointed rock mass at high temperatures. The results show that the joints affect the temperature field variation in rock mass, and the vertical and horizontal joint groups pose significantly greater influence than the inclined joint group on temperature field. The sensitivity of the joint internal friction angle and thermal expansion coefficient to the range of the plastic zone is relatively small. Under various joint spacings, the influence of horizontal and inclined joint groups on the plastic zone morphology decreases, while the vertical joint group exhibits an incremental influence on the plastic zone morphology. Similar to the influence of the temperature field, the vertical and horizontal joint groups have a significantly greater influence on the plastic zone range than the inclined joint group. Under various rock mass temperatures, the plastic zone in rock mass results in the occurrence of uneven expansions along the direction of the joint dip angle, which changes the potential failure direction of rock mass and increases the potential destruction degree of rock mass, whereas it exhibits a smaller uniform expansion perpendicular to the joint dip angle, and the boundary of the plastic zone coincides with the joint surface, relatively hindering the potential destruction degree of rock mass. The research results of this study have certain reference values for the stability control of jointed rock mass in high-temperature hydraulic tunnels. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of surcharge/unloading at both sides of the ground surface on an existing underground shield tunnel at varying burial depths. A large-scale indoor model experiment was conducted to study the vertical convergence deformation, tunnel settlement, and additional surrounding pressure of the tunnel at different burial depths when surcharge/unloading occurred at both sides of the ground surface. The effect of tunnel burial depth, surcharge mass, and uneven surcharge at both sides of the ground surface on the additional surrounding pressure of the existing underground shield tunnel was further investigated by theoretical calculation. The results indicate that under the same conditions, greater tunnel burial depth leads to reduced vertical convergence deformation, tunnel settlement, and additional surrounding pressure. Unloading can partially reduce the vertical convergence deformation and tunnel settlement, but it does not completely counteract the effect of the preceding surcharge. In cases of a symmetrical surcharge at both sides of the ground surface above the tunnel, the additional surrounding pressure of the tunnel is symmetrically distributed, with higher pressures at the arch top and arch bottom of the tunnel and lower pressures at the arch waist. This suggests that the arch top and arch bottom of the tunnel are vulnerable points under surcharge and require special attention. The surcharge above the tunnel has the most pronounced effect on the tunnel, followed by the surcharge at both sides of the ground surface, and, finally, the smallest effect from the bias load. [ABSTRACT FROM AUTHOR]

This study aims to explore the temperature field and mechanical characteristics of hydraulic tunnels during operation in an area with large temperature differences throughout a year. By relying on the measured displacement field change results of a water transmission tunnel in Xinjiang, a finite element calculation model applicable to the hydraulic tunnel-surrounding rock under the action of large temperature differences was established. Then, the FEM model was used to analyze the temperature field distribution and stress field variation of hydraulic tunnel-surrounding rock under the effect of large temperature differences. The results showed that, under the action of large temperature differences, the displacement of the cave top was the largest, followed by the cave bottom, and finally the cave waist. The obtained displacement field data using the calculation model in this study were basically consistent with the on-site measured data, and the displacement field change law was the same, indicating that the established finite element calculation model is reliable. When the ambient temperature was below zero, the freezing front gradually expanded to the depth of the surrounding rock along the tunnel radial direction, while the frozen rock at the intersection of the lining and the surrounding rock melted first when the ambient temperature was above zero. The stress in various parts of the surrounding rock of the hydraulic tunnel increased continuously. To be specific, the growth rate of the tensile stress at the cave bottom, the tensile stress at the cave top, and the compressive stress at the cave waist of the tunnel reached 0.052 MPa/year, 0.053 MPa/year, and 0.096 MPa/year, respectively, in the first year, but the increasing rate subsequently tended to slow down continuously. Therefore, in actual projects, attention should be focused on the effect of large temperature differences on the stress growth of tunnel-surrounding rocks at an early stage, especially the growth of compressive stress at the cave waist. Notably, there are a large number of symmetrical and asymmetric phenomena related to engineering in this study. [ABSTRACT FROM AUTHOR]

The superior characteristics of the silicon carbide metal-oxide-semiconductor field-effect transistor (SiC mosfet) allow its wide use for improving the efficiency and power density of power electronic systems. However, the higher switching speed exacerbates the problems of overshoot, oscillation, and electromagnetic interference (EMI), which need to be properly addressed. In this article, a novel stage-detection closed-loop active gate driver (AGD) based on the printed-circuit-board (PCB) Rogowski Coil is proposed for optimizing the switching performance of SiC mosfets. And its stage identification threshold design can weaken the influence of the varying nonlinear parameters, especially for the turn-on process. First, the gate driver trajectory and the switching process of the SiC mosfet are analyzed. The optimal driver parameter dynamic configuration among the existing stage-control schemes is defined and unified, which aims to optimize the tradeoff between the overshoot and switching loss. Then, the parameter design of the PCB Rogowski Coil is illustrated. And the operation principle and working process of the proposed AGD are introduced. Finally, the performance of the proposed AGD and the effectiveness of the stage-control schemes are verified in the double-pulse test under different conditions. The experimental results show that the proposed AGD can not only reduce the overshoot and suppress the oscillation but also optimize the compromise of the switching loss and switching time. [ABSTRACT FROM AUTHOR]

In order to study the effect of FeCl3 solution on the current, soil pH value, drainage volume, anode potential difference, energy consumption, and resistivity of electro-osmosis consolidation of soft clay with different moisture contents under a low temperature environment, we carried out 31 sets of model tests under different working conditions by using a self-made device and an improved Miller Soil Box. The test results showed that, under the same conditions, although the energy consumption coefficient of electro-osmosis had little change in the low temperature environment, the current, displacement, and electro-osmosis coefficient were obviously reduced, and the resistivity and anode potential difference was greatly increased, indicating that the low temperature environment reduces the efficiency of electro-osmosis of soft clay. After the anode was filled with FeCl3 solution, the current, water displacement, and electro-osmotic coefficient were clearly increased; the anode potential difference and electro-osmotic energy consumption coefficient were clearly decreased; and the resistivity was reduced to a certain extent, which indicates that the anode filled with FeCl3 solution is very beneficial in improving electro-osmotic efficiency and in saving energy. The electro-osmotic discharge after the anode filled with FeCl3 solution at low temperature was clearly higher than that after the anode was filled water at normal temperature, indicating that the effect of the anode filled with FeCl3 solution on electro-osmosis is greater than that of temperature. In the process of electro-osmosis of soft clay, the better the electro-osmosis effect, the smaller the pH value of the anode and the larger the pH value of the cathode. The pH value of the cathode and anode can be used as one of the indexes to reflect the electro-osmosis effect. [ABSTRACT FROM AUTHOR]

Dental implants occasionally fail for many reasons, especially peri-implantitis. The adhesion of bacteria to the surface of titanium is the initial factor in peri-implantitis. Therefore, the aim of this study was to assess the effect of a novel micro-arc oxidation (MAO) titanium on bacteria inhibition and regulation through periodontitis, and on a healthy saliva-derived biofilm, in vitro. MAO, sandblasting and acid etching (SLA), machined titanium and plasma-sprayed hydroxyapatite (HA) were selected for further study. The metabolic activity and biomass accumulation were tested using MTT (3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) and crystal violet assay after 24 h of anaerobic incubation. The structure was determined by scanning electron microscopy (SEM) and live/dead staining. Moreover, 16S rDNA sequencing was used to assess the microbial community. The results showed that biofilms on MAO were thinner compared to HA and SLA. In the periodontitis group, the biofilm accumulation and metabolic activity reached the highest levels in the HA group (p < 0.05); MAO titanium had the smallest biofilm accumulation and higher live/dead ratio; and the relative abundance of Lactobacillus in the SLA, HA and MAO groups increased significantly compared to the machined group (p < 0.05). In the healthy group, the relative abundance of Lactobacillus in the MAO group increased significantly compared to the other three groups (p < 0.05); the amount and metabolism activity of bacteria in the MAO group was lower (p < 0.05); MAO titanium had the least biofilm accumulation and a higher live/dead ratio. In conclusion, the novel MAO titanium had the ability to combat peri-implantitis by inhibiting the biofilm and regulating the microbial ecosystem to healthier conditions. [ABSTRACT FROM AUTHOR]

Theoretical analysis and a large number of experiments have proved that plasma components do not satisfy Boltzmann-Gibbs statistics and can be well described by nonextensive statistical mechanics, while new plasma parameters, electron nonextensive parameters, which are introduced to describe the nonextensive properties of plasma, cannot be diagnosed yet. Here we show measurement of electron nonextensive parameters of plasma with a nonextensive single electric probe. Our results show that nonextensive electric probe may play a role in plasma diagnosis, measuring nonextensivity of plasma and improving diagnostic accuracy of other plasma parameters. We expect the proposed nonextensive single electric probe can be starting point of more complex nonextensive electric probe. In addition, nonextensive electric probe is an important means to study various plasma waves and instability, turbulence, and anomalous transport, and a definite and quantitative test of the theory of nonextensive geodetic acoustic models will be relevant to such development.

Purpose: To study the clinical effect of endoscopic mucosal resection (EMR) in the treatment of early gastric cancer (EGC), and to evaluate the recovery and prognosis, so as to provide references for clinical selection of treatment methods., Methods: 120 patients with EGC were selected and randomly divided into the EMR group and the radical surgery group. Before surgery and 3 days after surgery, the levels of traumatic response-related indexes in serum [adrenocorticotropic hormone (ACTH), cortisol (Cor), gastrin (GAS) and motilin (MTL)] were assessed. Before surgery, 3 months and 1 year after surgery, the expression levels of tumor markers [carcinoembryonic antigen (CEA), carbohydrate antigen 19.9 (CA19.9), CA125 and CA724] were assessed. Before surgery and 3 days and 3 months after surgery, the immune function indexes [cluster of differentiation (CD)25+, CD28+ and inducible costimulator (ICOS)] were measured. Moreover, the clinical effect of surgery and the incidence rate of complications were compared between the two groups, and patients were followed up for at least 2 years to evaluate their prognosis., Results: The clinical cure rate of tumor resection was comparable in both groups, and the incidence rate of complications in the EMR group was significantly lower than that in the radical surgery group (p<0.05). The levels of tumor markers were significantly increased compared with those before surgery in both groups (p<0.05), but without significant differences between the two groups. Three days after surgery in the radical surgery group, ACTH and Cor were increased, while GAS and MTL were decreased, and the levels of immune indexes declined (p<0.05). In the EMR group, the above indexes had no significant differences compared with those before surgery. Three days after surgery, the survival and recurrence rate in the EMR group and the radical surgery group were 95.0% vs. 98.3% and 5.0% vs. 3.3%, respectively (p>0.05)., Conclusions: The treatment of EGC with EMR has comparable clinical effect and prognosis to the traditional radical surgery, which causes less damage to the body and gastrointestinal function and less inhibition on the immune function, so it is worthy of clinical application.