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.

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.

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.

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.

Applications of Normality Test in Statistical Analysis

In this study, to power comparison test, different univariate normality testing procedures are compared by using new algorithm. Different univariate and multivariate test are also analyzed here. And also review efficient algorithm for calculating the size corrected power of the test which can be used to compare the efficiency of the test. Also to test the randomness of generated random numbers. For this purpose, 1000 data sets with combinations of sample size n = 10, 20, 25, 30, 40, 50, 100, 200, 300 were generated from uniform distribution and tested by using different tests for randomness. The assessment of normality using statistical tests is sensitive to the sample size. Observed that with the increase of n, overall powers are increased but Shapiro Wilk (SW) test, Shapiro Francia (SF) test and Andeson Darling (AD) test are the most powerful test among other tests. Cramer-Von-Mises (CVM) test performs better than Pearson chi-square, Lilliefors test has better power than Jarque Bera (JB) Test. Jarque Bera (JB) Test is less powerful test among other tests.

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.

基于EDEM的倾式单螺旋排肥器排肥性能仿真分析

为提升传统螺旋式排肥器排肥均匀性,在仿真分析确定其排肥不均问题原因的基础上,设计了一种倾式单螺旋排肥器。通过理论分析确定了排肥器关键参数,利用EDEM仿真模拟倾式单螺旋排肥器的排肥过程,以螺旋排肥轮转速为试验因素,排肥均匀性变异系数为评价指标,进行单因素试验。试验结果表明,倾式单螺旋排肥器较传统螺旋排肥器的排肥均匀性变异系数提升了73.26%,螺旋排肥轮不同转速对排肥均匀性变异系数有着极显著影响(P<0.000 1),同时随着转速的增加其排肥均匀性变异系数逐渐减小,排肥均匀性变好。且螺旋排肥轮转速在75~120 r/min范围内达到最好效果,排肥均匀性变异系数稳定处于2.05%~4.04%,符合施肥机械质量评价技术规范。研究可为螺旋排肥器的优化设计提供参考。

水平圆盘式小白菜精量排种器的设计与试验

为提升小白菜机械化种植水平,以金宇盛辉四季小白菜种子为研究对象,设计一种带有导种槽型孔及采用清种后直接投种原理的水平圆盘式白菜精量排种器,并通过理论分析确定其关键参数。为分析小型手推式播种机作业速度对排种器工作性能的影响,以播种机作业速度为试验因素,单粒率、多粒率、空粒率为试验指标,运用EDEM软件进行虚拟仿真试验。结果表明:随着机器作业速度的增加,其排种性能先升后降,且在机器作业速度为0.5 m/s时排种性能最佳,排种单粒率为93.06%、多粒率为3.98%和空粒率为3.06%,并通过台架试验进行验证,得到台架试验结果与仿真试验结果之间的误差在3%以内,符合小白菜种子的播种农艺要求。

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.

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.

发酵型含乳饮料研究概况及新产品开发

对发酵乳饮料的工艺和品质研究进展进行描述。将香菇汁、枸杞汁和纯牛奶作为主要原料制作发酵型含乳饮料,利用单因素和正交试验对影响香菇枸杞发酵型含乳饮料的主要因素(枸杞汁添加量、香菇汁添加量、乳清蛋白添加量、发酵时间)进行分析,优化出最好工艺参数。结果表明,香菇枸杞发酵型含乳饮料最好参数是枸杞汁55%、香菇汁14.5%、乳清蛋白粉2.5%、发酵时间5h、白糖3%、牛奶25%、发酵剂0.1%。此发酵型含乳饮料各项指标符合国家标准要求,状态稳定、组织细腻、色泽均一,具独特风味,口感极好。

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.

鲜食玉米脱粒机的设计与试验

设计一种轴向滚筒式鲜食玉米脱粒机以实现变径脱粒,并针对鲜食玉米脱粒机的核心脱粒部件进行仿真分析,以分析所设计的脱粒机的性能。根据理论分析和仿真结果设计了脱粒样机,开展了脱粒试验。选取滚筒转速、陀螺转速、转轴轴距、为本次试验三个试验因素,以籽粒破损率及果穗未脱净率为试验指标。试验结果确定得到滚筒转速为86.5~128.5r/min、陀螺转速为213~297r/min、转轴轴距为46~56mm。本研究为鲜食玉米脱粒机的设计与制造提供了新的脱粒理论基础,有望推动鲜食玉米加工技术的进一步发展与应用。

石油污染场地浅层地下水监测式自然衰减效果评价

监测式自然衰减(Monitored Natural Attenuation,简称MNA)能够有效地修复石油污染场地,降低土壤及地下水中污染物的浓度,已经成为国内外的研究热点。文章采用统计学方法、Mann-Kendall test和溶质通量计算法,分析并计算场地地下水中总石油烃(TPH)浓度,评价石油污染场地地下水监测式自然衰减的效果。结果显示:石油污染场地中的TPH浓度呈现降低的趋势。污染晕内,不同位置的衰减率不同,污染晕内部更容易发生自然衰减作用;污染晕边缘的衰减作用则较小。MNA的衰减率为0.00876~0.10095 mg/(L·d);MNA的修复周期为1.3~10.6 a。

Temperature Variation and Mutation Analysis over the Past 59 Years in Shenyang

In this paper,based on the observation data of air temperature during 1951-2009 in Shenyang,the interannual and interdecadal variation of annual average temperature,maximum and minimum temperature in Shenyang were conducted the statistical analysis by means of linear trend estimation and mutation detection by using Mann-Kendall method.As was demonstrated in the results,the annual average temperature,maximum and minimum temperature in Shenyang showed an upward trend,whose linear tendency rate was 0.231,0.181 and 0.218 respectively.The increment trend of annual average temperature,maximum and minimum temperature was extremely clear.The increase in minimum temperature was more significant than that in mean temperature and maximum temperature.The abrupt change point of annual mean temperature in Shenyang appeared in 1981;the abrupt change point of annual mean maximum temperature appeared in 1994;the annual mean minimum temperature underwent mutation in 1978.

40a气候变化对扎龙湿地蒸散影响分析

利用扎龙湿地周边5气象站1961～2000年的气象数据，研究了湿地区域最高气温、最低气温、降雨量、2m高风速等气象因子的变化趋势，分析40a气候变化对湿地蒸散耗水产生的影响．气象因子趋势分析使用Mann—Kendall检验，芦苇沼泽蒸散耗水计算采用耦合上述气象因子的经验模型．结果表明，研究区域最高气温具有不显著的上升趋势（0．15℃／10a），最低气温呈现显著的上升趋势（O．74℃／10a），二者变化是非对称的；风速具有显著的下降趋势（-0．14m·s^-1／10a），而降雨量没有显著变化，芦苇蒸散量呈下降趋势（-22．9mm／10a）．最高气温、最低气温是影响蒸散量变化的主要因子，二者升温速度的差异决定蒸散量的变化趋势，气象因子的变化表征了近年来空气中悬浮物气溶胶的增加屏蔽了太阳辐射，进而引起净辐射的降低．

促进香菇多糖生物合成的热胁迫条件优化

以香菇(Lentinula edodes)808菌株为试验材料,通过单因素实验探讨不同热胁迫起始时间、胁迫温度、胁迫持续时间和恢复培养时间对香菇液体发酵胞内和胞外多糖总含量的影响,并采用正交试验L9(34)研究促进香菇多糖生物合成的最佳热胁迫条件。单因素实验结果表明,热胁迫温度、起始时间、持续时间和静置恢复时间4个因素对香菇多糖生物合成均有影响,正交试验筛选的最佳条件为热胁迫温度40℃,热胁迫起始时间为液体发酵第7.5天,胁迫持续时间9h,热胁迫后25℃静置恢复18h,在此条件下,香菇液体发酵产物多糖含量(胞内和胞外多糖总含量)为4.25g/L,是未做热胁迫处理多糖总含量(2.67g/L)的1.6倍。

一元线性回归方程的三种显著性检验的等价性分析

本文对一元线性回归方程的三种显著性检验方法(T检验法,F检验法,相关系数检验法)做了梳理,并给出了三种检验方法的一致性证明.利用R语言进行实例分析,对三种检验方法间的关系及作用进一步验证.

黑龙江省伊春市圆砾层地基承载力试验研究

利用浅层平板载荷试验和圆锥动力触探原位试验方法,对黑龙江省伊春市圆砾层进行地基承载力测试,获取了地基承载力特征值fak、变形模量E0与修正后的锤击数N63.5'的相关系数及经验公式。分析结果显示,研究区圆砾层变形量小,构造稳定,负重力强,地基承载力超过GB 50007—2011《建筑地基基础设计规范》标准规定值的30%以上,可为该地区建筑地基基础设计提供参考。

路基智能压实关键控制参数动态仿真及演变规律

为了对智能压实质量评价指标的变化规律进行定性分析,从其计算原理的角度剖析其变化机理。进一步通过Abaqus有限元数值仿真软件的二次开发,实现路基土智能压实过程中参数动态变化,有效提高数值仿真结果的准确性。针对影响智能压实质量评价指标CMV(压实质量测量值)的各因素(碾压速度、激振力、自重、激振频率以及碾压遍数)进行正交试验,从而分析各因素对CMV的影响趋势。最后,为了对路基土智能压实技术进行压实质量的均匀性分析,结合正交试验结果,通过单变量统计学正态分布3σ的方法以及空间统计学半变异函数的方法,分析CMV均匀性的分布以及智能压实技术的影响范围。研究结果表明各因素对压实质量的影响由强到弱依次为碾压速度、碾压遍数、激振频率、自重和激振力;智能压实技术在施工过程中,对周边的影响范围半径为3.15 m。