Investigation into Recent Temperature and Rainfall Trends in Mali Using Mann-Kendall Trend Test: Case Study of Bamako

Rainfall and temperature variability analysis is important for researchers and policy formulators in making critical decisions on water availability and use in communities. The Western Sahel, which comprises Mali is considered as one of the vulnerable regions to climate change, and also encountered the challenges of climatic shocks such as flood and drought. This research therefore sought to investigate climate change effects on hydrological events and trends in Sahelian rainfall intensity using Bamako (Mali) as a case study from 1991 to 2020, as limited data availability did not allow an extended period of study. Monthly observed data provided by MALI-METEO was used to validate daily rainfalls data from African Rainfall Climatology Version 2 (ARC2) satellite-based rainfall product on monthly basis. The validated model performance used Nash-Sutcliffe Efficiency (NSE) and Percent Bias (PBAIS) and gave results of 0.904 and 1.0506 respectively. Trends in annual maximum temperatures and rainfalls were analyzed using Mann-Kendall trend test. The result indicated that the trend in annual maximum rainfalls was decreasing, while annual total rainfall was increasing but not significant at 5% significance level. The rate of increase in annual total rainfalls was 0.475 mm/year according to the observed annual rainfall series and decreased to 0.68 mm/year in annual maximum. The analysis further found that annual maximum temperatures were increasing at the rate of 0.03°C/year at 5% significance level. To provide more accurate climate predictions, it is recommended that further studies on rainfall and temperature with data sets spanning 60 - 90 years be carried out.

A method to predict rockburst using temporal trend test and its application

Rockbursts have become a significant hazard in underground mining,underscoring the need for a robust early warning model to ensure safety management.This study presents a novel approach for rockburst prediction,integrating the Mann-Kendall trend test(MKT)and multi-indices fusion to enable real-time and quantitative assessment of rockburst hazards.The methodology employed in this study involves the development of a comprehensive precursory index library for rockbursts.The MKT is then applied to analyze the real-time trend of each index,with adherence to rockburst characterization laws serving as the warning criterion.By employing a confusion matrix,the warning effectiveness of each index is assessed,enabling index preference determination.Ultimately,the integrated rockburst hazard index Q is derived through data fusion.The results demonstrate that the proposed model achieves a warning effectiveness of 0.563 for Q,surpassing the performance of any individual index.Moreover,the model’s adaptability and scalability are enhanced through periodic updates driven by actual field monitoring data,making it suitable for complex underground working environments.By providing an efficient and accurate basis for decision-making,the proposed model holds great potential for the prevention and control of rockbursts.It offers a valuable tool for enhancing safety measures in underground mining operations.

Detecting Global Vegetation Changes Using Mann-Kendal(MK) Trend Test for 1982–2015 Time Period

Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understand the trends of vegetation cover, this research examined the spatial-temporal trends of global vegetation by employing the normalized difference vegetation index(NDVI) from the Advanced Very High Resolution Radiometer(AVHRR) Global Inventory Modeling and Mapping Studies(GIMMS) time series(1982–2015). Ten samples were selected to test the temporal trend of NDVI, and the results show that in arid and semi-arid regions, NDVI showed a deceasing trend, while it showed a growing trend in other regions. Mann-Kendal(MK) trend test results indicate that 83.37% of NDVI pixels exhibited positive trends and that only 16.63% showed negative trends(P < 0.05) during the period from 1982 to 2015. The increasing NDVI trends primarily occurred in tree-covered regions because of forest growth and re-growth and also because of vegetation succession after a forest disturbance. The increasing trend of the NDVI in cropland regions was primarily because of the increasing cropland area and the improvement in planting techniques. This research describes the spatial vegetation trends at a global scale over the past 30+ years, especially for different land cover types.

Test and Analysis of the Sound Insulation Performance of Four Types of Timber Structure Floors under Jumping Excitation

To improve the impact sound insulation performance of building floors and meet the objective requirements for living comfort of residents,in this article,three kinds of elastic cushion materials,Portuguese cork board,BGL insulation sound insulation foam board,and EPP polypropylene plastic foam board,are applied to the sound insulation of a light frame wood floor structure of the same bedroom and compared to the ordinary floor.This study uses the transfer function method and transient excitation method to measure the sound insulation,damping ratio,and elastic modulus of materials,as well as the sound insulation of the floor under the jumping excitation method of daily behavior.Through comparative analysis,the results and factors of improving the sound insulation performance of the floor are obtained,according to which three types of elastic cushion materials and the floor covering composed of them have higher vibration and noise reduction performance.Among them,the overall sound insulation performance of BGL board floor is the highest,followed by EPP board and cork board floor,and ordinary OSB floor is the lowest.Under the jumping excitation method,three floating floors can improve the impact sound insulation performance of the middle and low-frequency bands.

窄河谷大夹角挑流消能工体型优化研究

针对窄河谷大夹角条件下挑流消能易出现冲击两岸、冲坑过深的问题,采用水工整体模型试验方法对具有代表性的某水利枢纽深孔放水冲沙洞挑流鼻坎体型开展优化研究,并对比分析了水舌形态和下游河道冲刷特性。结果表明,不对称收缩的异型窄缝式消能工可使水流在狭窄河道归槽,水舌纵向拉伸效果较好,大幅减轻了河床冲刷;提出了收缩比、收缩角差、斜切面积比等特征参数适宜的挑流消能工体型,可供窄河谷大夹角条件下挑流消能设计参考。

Does ergogenic effect of caffeine supplementation depend on CYP1A2 genotypes? A systematic review with meta-analysis

Background:The ergogenic effects of caffeine intake on exercise performance are well-established,even if differences exist among individuals in response to caffeine intake.The genetic variation of a specific gene,human cytochrome P450 enzyme 1A2(CYP1A2)(rs762551),may be one reason for this difference.This systematic review and meta-analysis aimed to comprehensively evaluate the influence of CYP1A2 gene types on athletes’exercise performance after caffeine intake.Methods:A literature search through 4 databases(Web of Science,PubMed,Scopus,and China National Knowledge Infrastructure)was conducted until March 2023.The effect size was expressed as the weighted mean difference(WMD)by calculating fixed effects meta-analysis if heterogeneity was not significant(I^(2)≤50%and p≥0.1).Subgroup analyses were performed based on AA and AC/CC genotype of CYP1A2.Results:The final number of studies meeting the inclusion criteria was 12(n=666 participants).The overall analysis showed that the cycling time trial significantly improved after caffeine intake(WMD=-0.48,95%confidence interval(95%CI):-0.83 to-0.13,p=0.007).In subgroup analyses,acute caffeine intake improved cycling time trial only in individuals with the A allele(WMD=-0.90,95%CI:-1.48 to-0.33,p=0.002),but not the C allele(WMD=-0.08,95%CI:-0.32 to 0.17,p=0.53).Caffeine supplementation did not influence the Wingate(WMD=8.07,95%CI:-22.04 to 38.18,p=0.60)or countermovement jump test(CMJ)performance(WMD=1.17,95%CI:-0.02 to 2.36,p=0.05),and these outcomes were not influenced by CYP1A2 genotype.Conclusion:Participants with the CYP1A2 genotype with A allele improved their cycling time trials after caffeine supplementation.However,compared to placebo,acute caffeine supplementation failed to increase the Wingate or CMJ performance,regardless of CYP1A2 genotype.

Spatiotemporal changes in sunshine duration and its influential factors in Chongqing,China from 1961 to 2020

The surface solar radiation in most parts of the world has undergone a phenomenon known as global dimming and brightening,characterized by an initial decrease followed by an increase.As a result,the sunshine duration(SD)has decreased in the past 60 years.Against the backdrop of global dimming and brightening,SD has decreased to varying degrees in many regions of China.Using the observed data of SD,cloud amount(total cloud amount and low cloud amount,abbreviated as TCA and LCA),precipitation,and relative humidity(RH)from 34 meteorological stations in Chongqing during the period of 1961-2020,along with a digital elevation model(DEM)with a resolution of 90 m,this study analyzed the spatiotemporal variations and influencing factors of SD.The analysis employed methods such as linear regression,Mann-Kendall test,wavelet transformation,and DEM-based possible SD distributed model.The results showed that the annual SD in Chongqing has significantly decreased over the last 60 years,with a decreasing interannual trend rate(ITR)of 40.4 h/10a.Except for no obvious trend in spring,SD decreased significantly in summer,autumn and winter at the ITR of 21.1 h/10a,8.5 h/10a and 7.5 h/10a,respectively.An abrupt decrease in the annual SD was found in 1979.The difference before and after the abrupt decrease was 177.7 h.The difference before and after the abrupt decrease was 177.7 h.The annual SD possessed the oscillation period of 11a.The spatial heterogeneity of the mean annual SD during the last 60 years was obvious.The distribution of SD in Chongqing is high in the northeast and low in the southeast.In addition,about 73%of the total area in Chongqing showed a significant and very significant decreasing trend.The regions with significant changes are mainly concentrated in the regions with altitudes of 200~1000 m.The increasing LCA was the main cause of the decrease of the annual SD in the regions with 200-400 m altitude decreased the most and changed the most.Increasing LCA is the primary cause of the reduction in annual SD,showing a strong negative correlation coefficient of-0.7292.In Chongqing,PM2.5 concentration showed a significant decrease trend in annual,spring,autumn and winter during 2000-2020,but the significant correlation between PM2.5 concentration and SD was only in autumn and reached an extremely significant level.

消力坎对跌坎消力池坎控水跃影响的试验研究

跌坎消力池的设计一直是水利工程领域的热点问题,设计合理的消力池可以保证在短距离内有相当大的消能。笔者通过模型试验研究了跌坎消力池中不同高度和不同位置的消力坎对坎控水跃的影响,并与不加消力坎时消力池内相同水跃流态进行对比。结果表明:增设消力坎可有效缩短越长,减小共轭水深比,增大水跃消能率。随着消力坎距跃首距离的减小或者消力坎高度的增加,消力坎在减小水跃长、共轭水深比,增大消能率方面的作用越来越大。同时经过无量纲分析得出了消力坎设置在不同位置和高度条件下,相对水跃长度、共轭水深比和消能率的经验公式。该研究结果可为类似水工建筑物的设计提供参考。

Surface air temperature change in the Wuyi Mountains,southeast China

Detecting changes in surface air temperature in mid-and low-altitude mountainous regions is essential for a comprehensive understanding of warming trend with altitude.We use daily surface air temperature data from 64 meteorological stations in Wuyi Mountains and its adjacent regions to analyze the spatio-temporal patterns of temperature change.The results show that Wuyi Mountains have experienced significant warming from 1961 to 2018.The warming trend of the mean temperature is 0.20℃/decade,the maximum temperature is 0.17℃/decade,and the minimum temperature is 0.26℃/decade.In 1961-1990,more than 63%of the stations showed a decreasing trend in annual mean temperature,mainly because the maximum temperature decreased during this period.However,in 1971-2000,1981-2010 and 1991-2018,the maximum,minimum and mean temperatures increased.The fastest increasing trend of mean temperature occurred in the southeastern coastal plains,the quickest increasing trend of maximum temperature occurred in the northwestern mountainous region,and the increase of minimum temperature occurred faster in the southeastern coastal and northwestern mountainous regions than that in the central area.Meanwhile,this study suggests that elevation does not affect warming in the Wuyi Mountains.These results are beneficial for understanding climate change in humid subtropical middle and low mountains.

Assessment of the Spatio-Temporal Trends of Annual Extreme Temperature Indices over Tanzania during the Period of 1982-2022

Extreme weather and climatic phenomena, such as heatwaves, cold waves, floods and droughts, are expected to become more common and have a significant impact on ecosystems, biodiversity, and society. Devastating disasters are mostly caused by record-breaking extreme events, which are becoming more frequent throughout the world, including Tanzania. A clear global signal of an increase in warm days and nights and a decrease in cold days and nights has been observed. The present study assessed the trends of annual extreme temperature indices during the period of 1982 to 2022 from 29 meteorological stations in which the daily minimum and maximum data were obtained from NASA/POWER. The Mann-Kendall and Sen slope estimator were employed for trend analysis calculation over the study area. The analyzed data have indicated for the most parts, the country has an increase in warm days and nights, extreme warm days and nights and a decrease in cold days and nights, extreme cold days and nights. It has been disclosed that the number of warm nights and days is on the rise, with the number of warm nights trending significantly faster than the number of warm days. The percentile-based extreme temperature indices exhibited more noticeable changes than the absolute extreme temperature indices. Specifically, 66% and 97% of stations demonstrated positive increasing trends in warm days (TX90p) and nights (TN90p), respectively. Conversely, the cold indices demonstrated 41% and 97% negative decreasing trends in TX10p and TN10p, respectively. The results are seemingly consistent with the observed temperature extreme trends in various parts of the world as indicated in IPCC reports.

多断路器防跳检验装置研制

断路器防跳回路是二次控制回路的重要组成部分,在开展变电站综合检修、技术改造、设备投产等工作时需要进行多间隔防跳试验。针对传统防跳试验中存在的所需人员协同配合熟练度较高、多间隔校验时间长等问题,研制了一种多断路器防跳检验装置。该装置可由单人完成试验操作,并支持多间隔同步防跳试验,具有结构简单、携带方便、接线容易等优点,可有效缩短防跳试验时间以及优化人力资源配置,提升了试验工作的安全性。

车载DC-DC高压电性能评价

文章从电动汽车的标准和设计指标出发,详细研究电动汽车高压系统的电性能相关要求,重点分析DC-DC变换器的高压安全及高压部件的电气性能的评价方法及必要性。

Wavelet Analysis and Nonparametric Test for Climate Change in Tarim River Basin of Xinjiang During 1959-2006

Using wavelet analysis,regression analysis and the Mann-Kendall test,this paper analyzed time-series(1959-2006) weather data from 23 meteorological stations in an attempt to characterize the climate change in the Tarim River Basin of Xinjiang Uygur Autonomous Region,China.Major findings are as follows:1) In the 48-year study period,average annual temperature,annual precipitation and average annual relative humidity all presented nonlinear trends.2) At the 16-year time scale,all three climate indices unanimously showed a rather flat before 1964 and a detectable pickup thereafter.At the 8-year time scale,an S-shaped nonlinear and uprising trend was revealed with slight fluctuations in the entire process for all three indices.Incidentally,they all showed similar pattern of a slight increase before 1980 and a noticeable up-swing afterwards.The 4-year time scale provided a highly fluctuating pattern of periodical oscillations and spiral increases.3) Average annual relative humidity presented a negative correlation with average annual temperature and a positive correlation with annual precipitation at each time scale,which revealed a close dynamic relationship among them at the confidence level of 0.001.4) The Mann-Kendall test at the 0.05 confidence level demonstrated that the climate warming trend,as represented by the rising average annual temperature,was remarkable,but the climate wetting trend,as indicated by the rising annual precipitation and average annual relative humidity,was not obvious.

Use of clinical movement screening tests to predict injury in sport

Clinical movement screening tests are gaining popularity as a means to determine injury risk and to implement training programs to prevent sport injury. While these screens are being used readily in the clinical field, it is only recently that some of these have started to gain attention from a research perspective. This limits applicability and poses questions to the validity, and in some cases the reliability, of the clinical movement tests as they relate to injury prediction, intervention, and prevention. This editorial will review the following clinical movement screening tests: Functional Movement Screen?, Star Excursion Balance Test, Y Balance Test, Drop Jump Screening Test, Landing Error Scoring System, and the Tuck Jump Analysis in regards to test administration, reliability, validity, factors that affect test performance, intervention programs, and usefulness for injury prediction. It is important to review the aforementioned factors for each of these clinical screening tests as this may help clinicians interpret the current body of literature. While each of these screening tests were developed by clinicians based on what appears to be clinical practice, this paper brings to light that this is a need for collaboration between clinicians and researchers to ensure validity of clinically meaningful tests so that they are used appropriately in future clinical practice. Further, this editorial may help to identify where the research is lacking and, thus, drive future research questions in regards to applicability and appropriateness of clinical movement screening tools.

Hydrological Mann-Kendal Multivariate Trends Analysis in the Upper Yangtze River Basin

Hydrological events should be described through several correlated variables, so multivariate HFA has gained popularity and become an active research field during recent years. However, at present multivariate HFA mainly focuses directly on fitting the frequency distribution without confirming whether the assumptions are satisfied. Neglecting testing these assumptions could get severely wrong frequency distribution. This paper uses multivariate Mann-Kendal testing to detect the multivariate trends of annual flood peak and annual maximum 15 day volume for four control hydrological stations in the?Upper Yangtze River Basin. Results indicate that multivariate test could detect the trends of joint variables, whereas univariate tests can only detect the univariate trends. Therefore, it is recommended to jointly apply univariate and multivariate trend tests to capture all the existing trends.

First normative reference of standing long jump indicates gender difference in lower muscular strength of Macedonian school children

Background: This is the first study to publish the normative reference values for assessment of the level of muscular strength through the “standing long jump” test carried out on a large sample of Macedonian school children. The normative values encompass a wide span of years (6 - 18). Methods: The research was realized in a large sample of 12618 school children at the age of 6 to 18 years from Macedonia. The sample was divided in 14 groups, according to chronological age and each age group was divided into two subgroups according to the criteria of gender. For estimation of the morphologic characteristics, the following anthropometric measures have been applied: body height in standing position (cm), body weight (kg), as well as the body mass index (BMI). Children aged 6 or above were invited to take a standing long jump test. Results: Boys show statistically better results in all age categories in the standing long jump test than girls, and these differences become bigger with the increase of age, especially after the 14th year

Effects of 12 weeks of back-squat training program on jump performances and bone markers in female students

Background:The training program promoted improvements of jump abilities throughout the musculoskeletal system including bone markers.The aim of this study is to examine both the acute and chronic response of bone markers to resistance training program.Methods:Ten female students(age:18±0.7 years,body mass:63±3.6 kg;height:164±5.2 cm)participated in this study.They were recruited for a back-squat training program for 12 weeks,two days/week.The full-back squat protocol consisted of 3–5 sets×3–8 repetitions at 45–55%one repetition maximum.Testing sessions included a 5 jump test(5JT),standing long jump(SLJ),drop jump(DJ),and vertical jump(VJ).Results:Substantial improvements in all testing jumps(5JT:∆10%;P=0.000;ES=1.72;SLJ:∆7%;P=0.000;ES=1.33;DJ:∆11%;P=0.000;ES=0.72;VJ:∆20%;P=0.000;ES=1.84)were found during post program in comparison to pre-program results.Moreover,a significant change(P≤0.05)of bone markers during post-exercise compared to pre-exercise either before or after the training program.Only collagen type I carboxy-terminal peptide(CICP)levels elevated after the training program(pre-exercise only)compared to former levels.Conclusion:12 weeks of back-squat training program resulted greater acute improvements of jump abilities with adaptation in all musculoskeletal system including bone formation.

混凝土地面用水泥基耐磨材料钢轮测试法研究

对混凝土地面用水泥基耐磨材料的耐磨性能钢轮测试法进行研究,试验确定了耐磨材料合适的跳桌流动度为(135±5)mm;拌合物制备和成型过程中,耐磨材料试件表面需平整、压实、光洁;明确了试件安装、固定和磨痕除尘等试验条件。将钢轮法与滚珠轴承法的测试结果进行对比发现,二者对同种耐磨材料的耐磨性能评价基本一致,证明钢轮法试验可以用于混凝土地面用水泥基耐磨材料的耐磨性能测试和评价。

国外重复跳跃能力研究进展与展望

为全面认识重复跳跃能力,通过梳理国外相关文献,对国外重复跳跃能力的影响因素、测试方法、训练策略的研究进展进行探索。研究认为:(1)影响因素方面,生理学因素包括无氧能力、热环境、年龄和性别;生物力学因素包括肢体间协调性、垂直刚度、峰值力、腾空与触地时间、下肢关节角度和肌肉激活程度;训练学因素包括下肢爆发力、相对力量和反应力量。(2)测试方法方面,不同方法的区别与联系集中在动作模式、持续时间、间歇和跳跃频率;功率指标具有较高的信效度,个别方法中跳跃高度和疲劳指数指标缺乏信效度检验;测试方法多应用于以跳跃为主要形式的运动项目以及强调重复执行下肢爆发性动作的项目,可用于评估下肢爆发力耐力和无氧能力。(3)训练策略方面,急性训练包括深蹲练习和冷疗恢复;长期训练包括专项实战训练、增强式训练、增强式与抗阻的组合训练和重复冲刺训练。未来研究应关注:(1)探讨有氧能力对间歇跳跃表现的影响,以及重复跳跃时上肢摆臂动作生物力学参数的变化及其对跳跃表现的影响;(2)优化与开发符合专项特点的测试方法与指标;(3)进一步丰富急性和长期训练策略。

我国速度滑冰国家队运动员下肢不对称性的生物力学分析

目的采用常规非对称性测试方法,结合可模拟速度滑冰弯道姿态的发力训练器,探讨双边不对称性在速度滑冰项目中的表现形式,为速度滑冰下肢肌肉力量训练提供建议。方法对11名速度滑冰国家队长距离组男子运动员进行测试,以5000 m最佳成绩进行排序。分别对受试运动员进行单、双侧蹲跳测试,速度滑冰弯道侧蹬技术单次和连续单腿侧蹬动作模拟测试,分析不同指标结果以及与单、双边专项运动水平之间的相关性。结果双边不对称性的增加与优势侧(左腿)的运动表现呈正相关。随着侧蹬次数增加,专项运动能力与优势侧相关性降低,而与非优势侧(右腿)的相关性增加。结论优势侧的肌肉力量是影响速度滑冰运动员运动表现及双边不对称性的主要因素,而随着运动员侧蹬次数增加,对非优势侧的影响会逐渐加大。因此,运动员可通过单边模拟侧蹬的力量训练增强下肢肌肉力量,降低双边不对称性。