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This study aimed to assess the feasibility of utilizing geopolymer for repairing reinforced concrete beams. Three types of beam specimens were fabricated: benchmark specimens without any grooves, rectangular-grooved beams, and square-grooved beams. The repair materials employed included geopolymer material, and epoxy resin mortar, while carbon fiber sheets were used as reinforcement in select cases. The repair materials were applied to the rectangular and square-grooved specimens, with the carbon fiber sheets attached to the tension side of the specimens. To evaluate the flexural strength of the concrete specimens, a third-point loading test was conducted. The test results indicated that the geopolymer exhibited higher compressive strength and shrinkage rate compared to the epoxy resin mortar. Furthermore, the specimens reinforced with carbon fiber sheets demonstrated even greater strength than the benchmark specimens. In terms of flexural strength under cyclic third-point loading tests, the carbon fiber-reinforced specimens exhibited the ability to withstand over 200 cycles of repeated loading at 0.8 times the ultimate load. In contrast, the benchmark specimens could only withstand seven cycles. These findings highlight that the use of carbon fiber sheets not only enhances compressive strength but also improves resistance to cyclic loading.
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Thermoset glass fiber-reinforced polymers (GFRP) have been widely used in manufacturing and construction for nearly half a century, but the large amount of waste produced by this material is difficult to dispose of. In an effort to address this issue, this research investigates the reuse of thermoset GFRP waste in normal strength concrete (NSC) and controlled low-strength materials (CLSM). The mechanical performance and workability of the resulting concrete were also evaluated. To prepare the concrete specimens, the thermoset GFRP waste was first pulverized into granular pieces, which were then mixed with cement, fly ash, and water to form cylindrical concrete specimens. The results showed that when the proportion of thermoset GFRP waste aggregate in the concrete increased, the compressive strengths of NSC and CLSM would decrease. However, when incorporating 5% GFRP waste into CLSM, the compressive strength was 7% higher than concrete without GFRP. However, the workability of CLSM could be improved to meet engineering standards by adding an appropriate amount of superplasticizer. This finding suggests that the use of various combinations of proportions in the mixture during production could allow for the production of CLSM with different compressive strength needs. In addition, the use of recycled thermoset GFRP waste as a new aggregate replacement for traditional aggregates in CLSM was found to be a more sustainable alternative to the current CLSM combinations used in the market.
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Objective To investigate the application effect of the teaching method of team-based learning (TBL) combined with case-based learning (CBL) in the teaching of military positive psychology. Methods A total of 100 medical undergraduates of the class 2017 in Army Medical University were selected and randomly divided into TBL+CBL teaching group and traditional teaching group , with 50 undergraduates in each group . The teaching effect of the two methods was evaluated by assessment of theoretical knowledge and case analysis, questionnaire survey, and psychological evaluation. SPSS 19.0 was used to perform the t-test. Results Compared with the traditional teaching group, the TBL+CBL teaching group had significantly higher scores of theoretical knowledge (54.87±4.98 vs. 48.65±3.51) and case analysis (36.84 ±2.73 vs. 32.37 ±2.34). As for the results of psychological evaluation, compared with the traditional teaching group , the TBL+CBL teaching group had a significantly lower score of Symptom Checklist-90 (143.31±43.62 vs. 149.89±46.96) and significantly higher scores of ERC (48.76±5.37 vs.43.58 ±5.79) and GWB (107.87 ±15.56 vs. 102.32 ±12.13). In addition, the satisfaction rate of the TBL and CBL teaching method reached 95.83％ (46/50) in the TBL+CBL group. Conclusion The teaching method of TBL combined with CBL can achieve good teaching results in the teaching of military positive psychology and improve students' abilities of knowledge application and psychological adjustment. Therefore, it has good feasibility and applicability.
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Objective To investigate the relationships between mindfulness,anxiety and depression in surface warship soldiers and the mediating role of attentional control.Methods Chinese versions of State-Trait Anxiety Inventory ( STAI ) , Center for Epidemiologic Studies Depression Scale ( CES-D ) , Attentional Control Scale ( ACS) and the Five Facet Mindfulness Questionnaire ( FFMQ) were used to survey 475 sur-face warship soldiers. Single factor analysis of variance,correlation analysis and path analysis were conducted by SPSS 20.0 and Amos18.0. Results ①The scores of the state anxiety,trait anxiety and depression in the soldiers and noncommissioned officers were significantly higher than that of commissioned officers (P<0.05) . As for the state anxiety,trait anxiety,depression and attentional focusing,there were statistically significant differences among different educational levels (P<0.05) . Specifically,the lower educational level,the higher anxiety and depression,the lower control focusing. ② There were significant positive correlations among at-tentional focusing (27.12±4.43),attentional shifting (29.43±3.78) and mindfulness (120.27±11.16,r=0.49-0.51,P<0.01). State anxiety (38.65±10.07) was negatively correlated with attentional focusing,atten-tional shifting and mindfulness (r=-0.32--0.54, P<0.01). Similar results were observed for trait anxiety (41.28±8.79) and depression (9.97±10.13). ③Attentional focusing partially mediated the relationships be-tween state anxiety,trait anxiety,depression and mindfulness. Conclusion Anxiety and depression of sol-diers have obvious relationships with kinds of soldiers' rank and education level. Mindfulness and attentional control are vital protective factors for marine army's mental health. This study indicates that mindfulness may improve individuals' attentional focusing and attentional shifting,and ameliorate negative moods such as anx-iety and depression.
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Objective To analyze psychological stress level and features of recruits in training camp.Methods Psychological stress self-evaluation test (PSET) was applied to 1 600 recruits in training camp.Results ①There were 64 recruits(64/1600,4％) who had high level of psychological stress(T score ≥70).②The psychological stress symptoms of recruits in training camp mainly manifested as increased alertness (87.7％),sleep deprivation (57.6％),mental and physical fatigue (48.7％) and nervous irritability (45.2％).③Psychological stress levels of recruits with different ages and different levels of self-feeling in camp had significant differences(P＜0.05).Conclusion Recruits in training camp have partly excessive psychological stress responses,targeted emergency decompression trainings should be carried out in recruits.
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Objective To study military medical graduates' psychological elastic characteris-tics and the key influencing factors. Methods A comparative study of 817 graduate students and 597 undergraduate students in a military academy was conducted by using positive negative emotions, pos-itive and negative cognitive bias and Mental Resilience Scale. Independent sample t-test, single factor analysis of variance, correlation analysis, and step-wise regression analysis were conducted by SPSS 18.0 for data analysis. Results ①Resilience scores of postgraduate students were significantly lower than those of undergraduate students (76.01 ±11.43 vs. 80.00 ±10.26, t=-6.76, P<0.01). Resilience scores of military postgraduates were significantly higher than those of local postgraduates (77.18 ± 11.59 vs. 74.97±11.19, t=2.77, P<0.05). Resilience scores of female postgraduates were significantly lower than those of males (74.79 ±10.83 vs. 76.94 ±11.78, t=2.68, P<0.05), reflected in factors of tenacity and strength. ②Resilience and its factors were positively related to positive affect and atten-tion to positive information (r=0.448~0.625, P<0.01), while negatively related to negative affect and attention to negative information (r=-0.206~-0.448, P<0.01). ③Regression analysis showed that posi-tive and negative emotion, attention to positive and negative information can significantly predict re-silience, accounting for the variance of 53.7%. ④Positive and negative affect partially mediated the relationship between attention to positive information and positive affect and resilience. Conclusion Attention to positive information and positive affect may be potential targets for intervention to enhance the level of resilience among military medical postgraduate students.
