An innovative vehicle-mounted GPR technique for fast and efficient monitoring of tunnel lining structural conditions

AbstractThe health status of a railway tunnel should be regularly inspected during its service period to ensure safe operation. Ground-penetrating radar (GPR) has been used as a key technique for tunnel detection; however, so far, the measurements of GPR are only obtainable in contact mode. Such methods cannot meet the requirements of the operational tunnel disease census and regular inspections. Therefore, a new method—vehicle-mounted GPR with long-range detection—has been developed. It consists of six channels. The distance from its air-launched antenna to the tunnel lining is approximately 0.93 m–2.25 m. The scanning rate of each channel is 976 1/s. When the sampling point interval is 5 cm, the maximum speed can reach up to 175 km/h. With its speed and air-launched antenna, this system has a significant advantage over existing methods. That is, for an electrified railway, there is no need for power outages. Indeed, the proposed system will not interrupt normal railway operation. Running tests were carried out on the Baoji–Zhongwei and Xiangfan–Chongqing railway lines, and very good results were obtained

A study of college students’ openness personality and English learning anxiety

The present situation of college students’ English learning is one of the key research topics. Some studies have found that different personality traits have a great impact on the English learning effect of college students. However, there is still a lack of detailed analysis and summary on the impact of a specific personality on the degree of English learning anxiety. Therefore, the questionnaire that the thesis uses is developed according to the Foreign Language Classroom Anxiety Scale (FLCAS), conducts random surveys for college students from different regions, majors and ages, and makes statistical analysis of the collected data using SPSS to explore the relationship between openness personality traits and the English-learning anxiety level of college students. After discussion and analysis, the results of this study can be divided into two aspects. Firstly, from the anxiety of the subjects, 60% of the 408 subjects have low anxiety about English learning, and their scores were very close to the medium anxiety level (99≤b≤132), while almost only a few respondents were at the high anxiety level. Secondly, there is a linear relationship between openness personality and English learning anxiety. According to the total score, the correlation was 0.338, showing a moderate correlation, and the significance level is 0.01. According to the research results, teachers can improve the teacher-student relationship and relieve students’ anxiety by innovating teaching methods and evaluation systems. However, the results may vary due to confounding factors such as major, gender and age

Abrasion resistant semitransparent self-cleaning coatings based on porous silica microspheres and polydimethylsiloxane

Transparent, abrasion-resistant and superhydrophobic coatings have attracted considerable interest owing to their great advantages in applications. In this work, a semitransparent abrasion-resistant superhydrophobic coating was attained via depositing suspensions of porous silica microspheres and polydimethylsiloxane, followed by calcining and fluorating process. Herein, the porous silica microspheres were fabricated through a template method. Consequently, the coating exhibited a water contact angle of 153 degrees, a hexane contact angle of 100 degrees and an average optical transparency of 78%. Significantly, the coating displayed a robust resistance against sandpaper abrasion and knife-scratch. Furthermore, the coating also exhibited excellent self-cleaning performance even after it was contaminated by oil

A Modified Flexor Tendon Suture Technique Combining Kessler and Loop Lock Flexor Tendon Sutures

OBJECTIVES: In the present study, a novel single knot tenorrhaphy was developed by combining the modified Kessler flexor tendon suture (MK) with the loop lock technique. METHODS: A total of 48 porcine flexor digitorum profundus tendons were collected and randomly divided into six groups. The tendons were transversely cut and then repaired using six different techniques, the MK method, double knot Kessler-loop lock flexor tendon suture (DK), and single knot Kessler-loop lock flexor tendon suture (SK), each in combination with the epitendinous suture (P), and the same three techniques without P. Furthermore, by performing the load-to-failure tests, the biomechanical properties and the time taken to complete a repair, for each tenorrhaphy, were assessed. RESULTS: Compared to the MK+P method, DK+P was more improved, thereby enhancing the ultimate tensile strength. The SK+P method, which required fewer knots than DK+P, was easier to perform. Moreover, the SK+P repair increased the force at a 2-mm gap formation, while requiring lesser knots than DK+P. CONCLUSION: As opposed to the traditional MK+P method, the SK+P method was improved and exhibited better biomechanical properties, which may facilitate early mobilization after the repair

A Novel Method for Regional Short-Term Forecasting of Water Level

The water level forecasting system represented by the hydrodynamic model relies too much on the input data and the forecast value of the boundary, therefore introducing uncertainty in the prediction results. Tide tables ignore the effect of the residual water level, which is usually significant. Therefore, to solve this problem, a water level forecasting method for the regional short-term (3 h) is proposed in this study. First, a simplified MIKE21 flow model (FM) was established to construct the regional major astronomical tides after subdividing the model residuals into stationary constituents (surplus astronomical tides, simulation deviation) and nonstationary constituents (residual water level). Harmonic analysis (HA) and long short-term memory (LSTM) were adopted to forecast these model residuals, respectively. Finally, according to different spatial background information, the prediction for each composition was corrected by the inverse distance weighting (IDW) algorithm and its improved IDW interpolation algorithm based on signal energy and the spatial distance (IDWSE) from adjacent observation stations to nonmeasured locations. The developed method was applied to Narragansett Bay in Rhode Island. Compared with the assimilation model, the root-mean-square error (RMSE) of the proposed method decreased from 12.3 to 5.0 cm, and R2 increased from 0.932 to 0.988. The possibility of adding meteorological features into the LSTM network was further explored as an extension of the prediction of the residual water level. The results show that the accuracy was limited to a moderate level, which is related to the difficulty presented by using only wind features to completely characterize the regional dynamic energy equilibrium process

Practical strategy to produce ultrafine ceramic glaze: Introducing a polycarboxylate grinding aid to the grinding process

In this work, a polycarboxylate comb-like polymer was used as grinding aid for ceramic slurry, and the effect of addition of this grinding aid on ceramic process property was highlighted. The grinding efficiency of the polycarboxylate grinding aid (PG) in terms of the particle size distribution and specific surface of unit volume of the ceramic slurry being ground were investigated. Consequently, the PG that was synthesized via free radical polymerization under the condition of an APEG/AA/MA molar ratio of 0.3: 1: 1, an initiator dosage of 5 wt%, and a reaction time of 6 h at 90 degrees C, provided better grinding efficiency than those of the triethanolamine and other commercial grinding aids. Specifically, with a dosage of 0.21% and 2 h of grinding, the d(97) and d(50) of ceramic slurry decreased from 13.956 mu m and 2.043 mu m to 3.739 mu m and 0.561 mu m, respectively. The cumulative distribution, frequency distribution and SEM results exhibited a uniform particle size distribution for ceramic ground with PG-C. Furthermore, the sintering experiment indicated that a lower processing temperature was capable of producing ultrafine ceramic. These improvements indicated the potential application of the PG as an efficiency ceramic grinding aid, which further facilitating the preparation of uniform ultrafine slurry by a sand mill. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved

High-thermoelectric performance of TiO2-x fabricated under high pressure at high temperatures

We present the work about the initiative fabrication of multi-scale hierarchical TiO2-x by our strategy, combining high pressure and high temperature (HPHT) reactive sintering with appropriate ratio of coarse Ti to nanosized TiO2. Ubiquitous lattice defects engineering has also been achieved in our samples by HPHT. The thermoelectric performance was significantly enhanced, and rather low thermal conductivity (1.60 W m−1 K−1) for titanium oxide was reported here for TiO1.76. Correspondingly, a high dimensionless figure of merit (zT) up to 0.33 at 700 °C was realized in it. As far as we know, this value is an enhancement of 43% of the ever best result about nonstoichiometric TiO2 and the result is also exciting for oxide thermoelectric materials. The moderate power factor, the significantly reduced thermal conductivity and the remarkable synergy between electrical properties and thermal conductivity are responsible for the excellent thermoelectric performance. We develop a facile strategy for preparing multi-scale hierarchical TiO2-x and its superior ability to optimize thermoelectric performance has been demonstrated here