大直径灌注桩后注浆施工及试验研究

通过西安北站大直径灌注桩后注浆试桩试验结果,分析对比后注浆灌注桩单桩竖向承载力的提高幅度以及承载力估算值与实测值的差别,根据灌注桩后注浆现场施工出现的问题及处理过程,提出后注浆试桩时,优化后注浆参数是试桩的重要内容,并总结优化后注浆参数中注浆阎设置及注浆量选取的具体步骤和方法。     

与一般球面三角形关联的空间体体积

球面几何已列为高中数学课程选修内容,球面几何的知识在实际中有重要的应用,如航海、航空领域等。利用积分的方法研究了与一般球面三角形关联的空间体体积。     

Effect of different velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles

This study compared the effects of two velocity loss thresholds during a power-oriented resistance training program on the mechanical capacities of lower-body muscles. Twenty men were counterbalanced in two groups (VL10 and VL20) based on their maximum power capacity. Both groups used the same exercises, relative intensity and repetition volume, only differing in the velocity loss threshold of each set (VL10: 10% vs. VL20: 20%). Pre- and post-training assessments included an incremental loading test and a 15-m linear sprint to assess the force- and load-velocity relationships and athletic performance variables, respectively. No significant between-group differences (P > 0.05) were observed for the force-velocity relationship parameters (ES range = 0.15–0.42), the MPV attained against different external loads (ES range = 0.02–0.18) or the 15-m sprint time (ES = 0.09). A high between-participants variability was reported for the number of repetitions completed in each training set (CV = 30.3% for VL10 and 29.4% for VL20). These results suggest that both velocity loss thresholds induce similar changes on the lower-body function. The high and variable number of repetitions completed may compromise the velocity-based approach for prescribing and monitoring the repetition volume during a power-oriented resistance training program conducted with the countermovement jump exercise.     

Can changes in resistance exercise workload influence internal load,countermovement jump performance and the endocrine response?

This study examined the influence of differing volume load and intensity (%1 repetition maximum[%1RM]) resistance exercise workouts on session rating of perceived exertion (sRPE) countermovement jump (CMJ) performance and endocrine responses. Twelve participants performed a workout comprising four exercises (bench press, back squat, deadlift and prone bench pull) in randomised order as either power (POW); 3 sets × 6 repetitions at 45%1RM × 3 min inter-set rest, strength (ST); 3 sets × 3 repetitions at 90%1RM × 3 min inter-set rest, or hypertrophy (HYP); 3 sets × 10 repetitions at 70%1RM × 1 min inter-set rest in a randomised-crossover design. CMJ performance and endocrine responses were measured immediately pre-, post-, 12, 24, 48 and 72 h post-exercise. POW sRPE (3.0 ± 1.0) was lower than ST (4.5 ± 1.0) (P = 0.01), and both were lower than HYP (8.5 ± 1.0) (P = 0.01). Duration of CMJ decrement was longer (P ≤ 0.05) for HYP (72 h) compared to POW (12 h) and ST (24 h). Testosterone concentration was greater (P ≤ 0.05) immediately post-exercise in HYP compared to POW and ST. In conclusion, less inter-set rest, greater volume load and intensity (%1RM) may increase sRPE, duration of CMJ performance decrement and testosterone responses in resistance exercise.     

Determination of thigh volume in youth with anthropometry and DXA: Agreement between estimates

Abstract

This study examined the agreement between estimates of thigh volume (TV) with anthropometry and dual-energy x-ray absorptiometry (DXA) in healthy school children. Participants (n=168, 83 boys and 85 girls) were school children 10.0–13.9 years of age. In addition to body mass, height and sitting height, anthropometric dimensions included those needed to estimate TV using the equation of Jones & Pearson. Total TV was also estimated with DXA. Agreement between protocols was examined using linear least products regression (Deming regressions). Stepwise regression of log-transformed variables identified variables that best predicted TV estimated by DXA. The regression models were then internally validated using the predicted residual sum of squares method. Correlation between estimates of TV was 0.846 (95%CI: 0.796–0.884, S_y·x=0.152L). It was possible to obtain an anthropometry-based model to improve the prediction of TVs in youth. The total volume by DXA was best predicted by adding body mass and sum of skinfolds to volume estimated with the equation of Jones & Pearson (R=0.972; 95%CI: 0.962–0.979; R ²=0.945).     

The effect of training on aerobic power characteristics of young cross‐country skiers

The influences of growth, training and various training methods were investigated by analysing long‐term training effects in young cross‐country and biathlon skiers (n = 129). Some athletes (n = 49) were studied six times in three years and some at least once a year during a four year period (n = 48). During three summer training periods skiers emphasized either intensive training or distance training or continued to train normally. The results indicated that maximal oxygen uptake (VO₂ max) and heart volume increased between 15 and 20 years of age and the most significant changes in heart volume were observed between 16 and 18 years of age. International level skiers were able to increase their VO₂ max and heart volume even after 20 years of age. Anaerobic threshold (AT, ml kg^‐1 min^‐1) increased like VO₂ max but when expressed as a percentage of VO₂ max, the AT was similar in every age group over 16 years of age. Intensive training at the intensity of anaerobic threshold or higher was observed to be most effective in producing improvements in VO₂ max. Low‐intensity distance training was more effective in producing improvements in anaerobic threshold.     

Recovery of pulmonary diffusing capacity after maximal exercise

Abstract

Pulmonary diffusing capacity (Dl_co), together with spirometric variables, arterial oxygen tension (paO₂) and cardiac output were determined before and at intervals after maximal arm cranking, treadmill running and erogmeter rowing. Independent of the type of exercise, Dl_co increased immediately post‐exercise from a median 13.6 (range 7.3–16.3) to 15.1 (9.3–19.6) mmol min^‐1 kPa^‐1 (P <0.01). However, it decreased to 11.6 (6.9–15.5) mmol min^‐1 kPa^‐1 (P <0.01) after 24 h with cardiac output and paO₂ at resting values, and Dl_co normalized after 20 h. Thoracic electrical impedance at 2.5 and 100 kHz increased slightly post‐exercise, indicating a decrease in thoracic fluid balance, and there were no echocardiographic signs of left ventricular failure at the time of the decrease in Dl_co. Also, active muscle (limb) circumference and volume, and an increase in haematocrit from 43.8 (38.0–47.0) to 47.1 (42.7–49.8) (P <0.01), had normalized at the time of the decrease in Dl_co. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, peak and peak mid‐expiratory flows did not change. However, total lung capacity increased from 6.8 (5.0–7.6) to 7.0 (5.1–7.8) litres (P <0.05) immediately after exercise and remained elevated at 6.9 (5.1–8.7) litres (P <0.05) when a decrease in Dl_co was noted. The results demonstrate that independent of the type of maximal exercise, an approximate 15% reduction in Dl_co takes place 2–3 h post‐exercise, which normalizes during the following day of recovery.     

Comparison of Hydrostatic Weighing at Residual Volume and Total Lung Capacity in Children

Abstract

The influence of perceptions of the motivational climate and perceived ability on situational motivation and the physical activity behavior of 213 male and 229 female adolescent physical education students (M age= 12.56 years; SD = 0.96) was examined over a 3-day period. A significant age by gender interaction emerged, with physical activity declining from the sixth to eighth grade. The decline was more pronounced among female than male students. Perceptions of a mastery climate were strongly related to more self-determined forms of situational motivation. In contrast, perceptions of a performance climate were strongly related to less self-determined forms of situational motivation. Results of a hierarchical regression analysis revealed gender, perceived ability, and perceptions of a mastery climate to explain a significant amount of variance in physical activity. These findings suggest that promoting a mastery oriented motivational climate in physical education will foster self-determined situational motivation and physical activity.     

基于ARIMA模型的体育彩票销量预测——以上海为例

对未来体彩销量预测分析,可以为体彩产品设计、营销推广提供科学依据。本文以上海为例,采用ARIMA模型对2009年1月-2013年3月的上海体育彩票的月度销售数据进行时间序列分析,并预测出2013-2015三年上海体育彩票的销量,从而对上海体育彩票的销量增长趋势进行分析。     

新工科背景下流体力学教学方法研究与实践

针对新工科建设背景和需求,分析流体力学在建筑环境与能源应用工程专业中的地位,探索流体力学的教学新模式。在课程设置上进行学科交叉、融合;在理论教学过程中,结合专业综合实验台进行讲述;课程实验打破学科之间的壁垒,锻炼学生的动手能力,拓宽学生的知识领域,增强学生的专业技能。