Comparative Analysis of Climatic Change Trend and Change-Point Analysis for Long-Term Daily Rainfall Annual Maximum Time Series Data in Four Gauging Stations in Niger Delta

The aim of this study is to establish the prevailing conditions of changing climatic trends and change point dates in four selected meteorological stations of Uyo, Benin, Port Harcourt, and Warri in the Niger Delta region of Nigeria. Using daily or 24-hourly annual maximum series (AMS) data with the Indian Meteorological Department (IMD) and the modified Chowdury Indian Meteorological Department (MCIMD) models were adopted to downscale the time series data. Mann-Kendall (MK) trend and Sen’s Slope Estimator (SSE) test showed a statistically significant trend for Uyo and Benin, while Port Harcourt and Warri showed mild trends. The Sen’s Slope magnitude and variation rate were 21.6, 10.8, 6.00 and 4.4 mm/decade, respectively. The trend change-point analysis showed the initial rainfall change-point dates as 2002, 2005, 1988, and 2000 for Uyo, Benin, Port Harcourt, and Warri, respectively. These prove positive changing climatic conditions for rainfall in the study area. Erosion and flood control facilities analysis and design in the Niger Delta will require the application of Non-stationary IDF modelling.

Driving Force Analysis of Land Cover Change in Ulan Buh Desert Based on Markov Chain

The Ulan Buh Desert has a fragile natural environment, which is in the western part of Inner Mongolia arid climate zone and the farming and animal husbandry ecotone. In order to explore the driving force mechanism of the Land Cover Change, the paper constructed the natural-human driving force model by the Markov Chain based on Landsat MSS 1973, 1977 remote sensing image data, analyzed the naturalhuman driving force contribution rate to the Land Cover Change in Ulan Buh Desert. The results showed that in 1989-2013 the main driving force of the Ulan Buh Desert Land Cover Change is the natural factors, average contribution rate is 89.46%, then is the human driving force, the rate is 10.54%. The natural-human driving force contribution rate for every land cover type is different, in natural part, the minimum rate is saline-alkali land for 45.20%, while the maximum is sandy land(90.63%). The human driving force rate of forest land, grassland and water was negative, it shows that human factors slows down or hinder the growth of this kind of land cover. Because of the humanistic attribute, the natural effect of the cultivated land and construction land was abandoned, the rates of human driving are significantly different: the change of human driving force is 24.94%, while the change of construction land is 62.9%.

考虑RoCoF约束的新能源电力系统惯量分区配置方法

分析了大规模新能源电力系统按分区配置惯量的必要性,并对此给出电压源型换流器采用功率同步控制以配置虚拟惯量的建议。据此,提出一种考虑频率变化率约束的惯量分区配置方法。该方法先将待研究系统按频率响应特性的一致程度进行分区,然后结合分区内部扰动、分区间联络线上功率变化和负荷电压响应等因素计算扰动情况下各分区的最大不平衡功率,从而以分区为单位得到惯量需求并进行配置。最后,基于华东电网规划算例,说明了苏北沿海电网等分区的惯量配置需求,并验证所提惯量分区配置方法的有效性。

Comparative transcriptome analysis on the alteration of gene expression in ayu （Plecoglossus altivelis）larvae associated with salinity change

Ayu(Plecoglossus altivelis) fish, which are an amphidromous species distributed in East Asia, live in brackish water(BW) during their larval stage and in fresh water(FW) during their adult stage. In this study, we found that FW-acclimated ayu larvae exhibited a slower growth ratio compared with that of BW-acclimated larvae. However, the mechanism underlying FW acclimation on growth suppression is poorly known. We employed transcriptome analysis to investigate the differential gene expression of FW acclimation by RNA sequencing. We identified 158 upregulated and 139 downregulated transcripts in FW-acclimated ayu larvae compared with that in BW-acclimated larvae. As determined by Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway mapping, functional annotation of the genes covered diverse biological functions and processes, and included neuroendocrinology, osmotic regulation, energy metabolism, and the cytoskeleton. Transcriptional expression of several differentially expressed genes in response to FW acclimation was further confirmed by real-time quantitative PCR. In accordance with transcriptome analysis, iodothyronine deiodinase(ID), pro-opiomelanocortin(POMC), betaine-homocysteine S-methyltransferase 1(BHMT), fructose-bisphosphate aldolase B(aldolase B), tyrosine aminotransferase(TAT), and Na^+-K^+ ATPase(NKA) were upregulated after FW acclimation. Furthermore, the m RNA expressions of b-type natriuretic peptide(BNP) and transgelin were downregulated after FW acclimation. Our data indicate that FW acclimation reduced the growth rate of ayu larvae, which might result from the expression alteration of genes related to endocrine hormones, energy metabolism, and direct osmoregulation.

Effect of different stretching strategies on the kinetics of vertical jumping in female volleyball athletes

目的:探究静力性拉伸(SS)和专项化动力性拉伸(DS)对高水平女运动员(19.9±1.6岁,1.80±0.06 m、76.87±9.95 kg)动力学指标(峰值力、起跳时间、发力速度)的影响。方法:收集3天的数据(随机选取研究对象,并安排对照训练)。在每一个拉伸组(SS组vs.DS组vs.对照组)的持续时间相同(总时间7 min;每一肌群进行30 s)。拉伸后1 min和15 min,受试者在测力台上进行下蹲式纵跳测试。与静力拉伸后1 min相比,动力拉伸组发力速度、峰值力以及腾空时间等动力学参数明显提高,但在15 min时没有发现显著作用。结论:当训练和比赛要求最快的跳跃,女运动员应结合动力性拉伸而不是静力拉伸作为赛前热身的一部分,但热身应在15 min之内进行以获得最大收益。

Piecewise linear representation of time series based on mean trend in sliding window

Seismic data show some important characteristics,such as big volume and strong timeliness.Specific to the time series data of earthquake precursory observations,a piecewise linear representation based on the sliding window mean value(PLR MTSW)algorithm is proposed.With this algorithm,the mutation points can be identified accurately according to the rate of mean value change,while the main features of time series are maintained well.This algorithm can also smooth the noise and improve the compression accuracy with sliding window.Meanwhile the local extreme points can be identified effectively according to the change of mean value trend within window.

Magnetic Field Induction and Time Intervals of the Electron Transitions Approached in a Classical and Quantum-Mechanical Way

The motion of electron wave packets of a metal is examined classically in the presence of the magnetic field with the aim to calculate the time intervals between two states lying on the same Fermi surface. A lower limiting value of the transition time equal to about 10–18 sec is estimated as an average for the case when the states are lying on the Fermi surface having a spherical shape. Simultaneously, an upper limit for the electron circular frequency in a metal has been also derived. A formal reference of the classical transition time to the time interval entering the energy-time uncertainty relations known in quantum mechanics is obtained.

Estimating time-based instantaneous total mortality rate based on the age-structured abundance index

The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch forecast,and fisheries management. A catch curve-based method for estimating time-based Z and its change trend from catch per unit effort(CPUE) data of multiple cohorts is developed. Unlike the traditional catch-curve method,the method developed here does not need the assumption of constant Z throughout the time,but the Z values in n continuous years are assumed constant,and then the Z values in different n continuous years are estimated using the age-based CPUE data within these years. The results of the simulation analyses show that the trends of the estimated time-based Z are consistent with the trends of the true Z,and the estimated rates of change from this approach are close to the true change rates(the relative differences between the change rates of the estimated Z and the true Z are smaller than 10%). Variations of both Z and recruitment can affect the estimates of Z value and the trend of Z. The most appropriate value of n can be different given the effects of different factors. Therefore,the appropriate value of n for different fisheries should be determined through a simulation analysis as we demonstrated in this study. Further analyses suggested that selectivity and age estimation are also two factors that can affect the estimated Z values if there is error in either of them,but the estimated change rates of Z are still close to the true change rates. We also applied this approach to the Atlantic cod(G adus morhua) fishery of eastern Newfoundland and Labrador from 1983 to 1997,and obtained reasonable estimates of time-based Z.

Long Term Assessment of Aerosol Radiative Forcing over Selected Sites of East Africa

Atmospheric aerosols have contributed to radiative forcing through direct and indirect mechanisms. Aerosol effects are important in computing radiative forcing estimates for the past, current and future climate. In this study, a comprehensive assessment of regional aerosol radiative forcing, Optical Properties of Aerosol and Clouds (OPAC) model (wavelength range of 0.25 - 4.0 μm) over selected sites in East Africa was done. Aerosol optical properties constituted the inputs of a Radiative Transfer Model (RTM). Op-tical properties investigated included Aerosol Optical Depth (AOD), Single Scattering Albedo (SSA) and Asymmetry Parameter (AP). Aerosol Radiative Forcing (ARF) during the study period at the surface (SFC), top of the atmosphere (TOA) and the atmosphere (ATM) was estimated to be -18.4 ± 1.4 W·m-2, +1.1 ± 0.3 W·m-2 and +19.5 ± 2.5 W·m-2, respectively. This corresponds to an increment in net atmospheric forcing at a heating rate of about 0.55 ± 0.05 K/day (0.41 ± 0.03 to 0.78 ± 0.03 K/day) in the lower troposphere. The study points out the significant role played by atmospheric aerosols in climate modification over the area of study. It is recommended that a further assessment be done in view of uncertainties that may impact on the findings and which were not within the scope of this research.

Higher-order differential variational principle and differential equations of motion for mechanical systems in event space

In this paper we study the higher-order differential variational principle and differential equations of motion for mechanical systems in event space. Based on the higher-order d'Alembert principle of the system, the higher-order velocity energy and the higher-order acceleration energy of the system in event space are defined, the higher-order d'Alembert–Lagrange principle of the system in event space is established, and the parametric forms of Euler–Lagrange, Nielsen and Appell for this principle are given. Finally, the higher-order differential equations of motion for holonomic systems in event space are obtained.

泸定地震人员死亡、失联数量的变化特征及地质灾害对其的影响

搜集了泸定6.8级地震人员死亡和失联资料,通过与近10年典型破坏性地震震例进行案例对比,定量分析了泸定地震人员死亡、失联数量随时间变化的特征。结合应急救援工作实际,梳理、归纳主要原因,同时系统分析了地质灾害对人员死亡率及失联率的影响。探讨山区地震灾害及救灾特点,提出山区复杂环境下地震灾害信息核查报送及人员搜救能力提升建议。

川西南下寒武统筇竹寺组页岩旋回地层学研究

[目的]四川盆地下寒武统的泥页岩不仅包含重要的环境生命演化信息,同时也是我国当前页岩气勘探开发的重点层位,对其开展精细地层年代学研究具有生产及科研的双重价值。[方法]为了更准确地探明四川盆地下寒武统筇竹寺组黑色页岩层序沉积特征,对川西南地区金页1井筇竹寺组页岩地层开展了旋回地层学研究。[结果与结论](1)通过分析不同测井曲线测井响应特征,认为钾元素测井序列是最适合古环境、古气候的替代指标。(2)将钾元素深度序列进行频谱分析和滑动窗口频谱分析,识别出偏心率和斜率周期(405 kyr,131 kyr,95 kyr,36.4 kyr,28.2 kyr);并结合相关系数分析,以不同沉积速率为限,将整段曲线划分为四段,分别进行405 kyr长偏心率周期的带通滤波;以周缘地区的年代地层年龄526.86±0.16 Ma为年龄控制点,建立了金页1井筇竹寺组的“浮动”天文年代标尺。(3)筇竹寺组共记录了29个长偏心率周期,四段地层的最优沉积速率分别为2.5,2.9,3.4和4.8 cm/kyr。(4)以405 kyr的轨道调谐为基础的沉积噪音模型DYNOT及ρ1曲线重建了筇竹寺组沉积时期相对海平面变化曲线;以该曲线为理论参照,在筇竹寺组中划分了4个三级层序,识别出4个最大海泛面及与之对应的T-R旋回;4个三级层序的沉积时限从下到上为3.18,2.03,2.97和3.63 Ma,分别包含了8个,5个,7个和9个长偏心率周期。(5)海平面变化曲线的低值对应了全球碳同位素负偏,推测是由于海平面的下降引起的有机质发生氧化,并向海水释放碳同位素偏轻的无机碳,形成碳同位素负偏。

AN ATMOSPHERIC MOTION EQUATION BUILT ON THE CONSERVATIVE RELATIONSHIP OF THE ANGULAR MOMENTUM EXCHANGE BETWEEN THE SOLID EARTH AND THE ATMOSPHERE ON SEASONAL-ANNUAL TIMESCALE

Within the seasonal-annual timeseale,there exists an angular momentum conservative exchange relationship be-tween the solid earth and the atmosphere,and their angular momentum exchange not only can cause variations inlength-of-day(LOD)but also can express anomalies in atmospheric general circulation.Therefore,their angular mo-mentum exchange mechanism should be introduced into the general circulation model.Considering the angular momentum anomalous exchange caused by the air-earth interface friction effect,awhole-layer atmospheric motion equation is derived in this paper including the earth spin anomalous friction forceparameterized by using the change in the earth rotation rate.Through analysing the equation,it shows that the magni-tude of the earth spin anomalous friction force is the same as that of Coriolis force on seasonal-annual timescale.

Analysis of land use change and its driving force in the Longitudinal Range-Gorge Region

关于陆地使用度，陆地使用变化率以及各种各样的陆地使用的地区性的差别的研究录入西南纵的范围峡区域(LRGR ) 被执行了在上地区性并且县规模。从社会经济的看法，我们也在研究区域分析了陆地使用变化的开车机制和各种各样的驱动力的相应空间范围。研究结果显示在地区性的规模上，农田，森林和草地在 LRGR，和草地严厉地衰退的陆地使用表演的结构的变化填写陆地使用的主要身体，农田增加和森林保持稳定。在县规模上，陆地使用被那陆地使用水平描绘是相对低的，并且陆地使用度，全面变化率和相对变化在不同陆地使用类型之中评价仍然存在。由分析，在 LRGR 的陆地使用变化被投资主要驾驶人力和物理资源，社会经济产量水平，自然灾难骚乱的紧张和工人的教育水平的紧张。然而， regionalism 在不同驱动力类型的影响范围存在。

基于拆除构件法的大跨度预应力网架屋盖-框架结构的内力重分布分析

采用有限元软件SAP2000对大跨度预应力网架屋盖—框架结构失去长跨中柱前后的构件内力时程变化,并选择沿拆除柱纵跨方向和横跨方向的构件为研究对象,得出结论,在柱轴力变化方面,长跨中柱的失效主要会导致沿纵跨方向的相邻一跨柱的轴力增加幅度较大,其余柱变化幅度较小,且会随距离增大逐渐变小;在梁端弯矩变化方面,与失效点相连梁端弯矩变化最大,沿纵跨方向的梁在柱失效后呈一端上部受拉,另一端下部受拉的状态,而沿横跨方向的预应力梁则是连接端弯矩有增大,另一端弯矩曲线在初始值处波动,弯矩最后无明显变化,其余梁则随距离增大,所受影响越小;在杆件轴力变化方面,上弦杆轴力在纵跨方向随着离失效点距离变远而变小,曲线变化规律明显。

成渝经济区植被生态质量演变特征及驱动力分析

利用MODIS NDVI数据反演成渝经济区2005年-2020年植被覆盖度(VFC)、植被净初级生产力(NPP),构建植被生态质量指数(Q)。通过趋势线性分析、相关性分析、残差分析,研究2005年-2020年成渝经济区植被生态质量时空变化特征,探索成渝经济区植被生态质量与气候和人类活动等影响因素的关系。结果表明:(1)2005年-2020年成渝经济区植被覆盖度达95%,NPP显著升高地区达93%,植被生态质量指数(Q)显著增加地区达92%,三者之间空间分布相对一致,植被生态质量整体提升;(2)通过趋势分析,降水、温度增加的空间分布和植被生态质量指数(Q)增加的空间分布范围相对一致,表明气候对改善植被生态质量有重要的驱动作用;相关性分析显示,植被生态质量指数(Q)与降水呈正相关,与温度呈负相关,且降水与植被生态质量指数(Q)的相关性强于温度;(3)驱动分区显示,成渝经济区植被生态质量变化约14.35%地区受气候因素驱动,约85.65%地区受非气候因素(自然灾害和人类活动等)的驱动;通过残差分析,2005年-2020年成渝经济区人类活动对植被的正面作用大于负面作用,说明成渝经济区植被生态质量的时空变化是气候因素和人类活动共同影响的结果。

基于Landsat的高山松地上生物量动态变化估测模型构建

以香格里拉市高山松为研究对象,基于1987—2017年的国家森林资源清查固定样地和对应年的Landsat TM/OLI数据提取对应的遥感因子,计算30 a期间生物量和遥感因子的5、10 a定期变化量、年平均变化量、5、10 a变化率;采用多元线性回归(MLR)和随机森林(RF)方法构建地上生物量模型,提高高山松森林AGB动态变化遥感估测的精度。结果表明:基于5种变化量类型的RF模型效果均优于相应的MLR模型,RF模型中采用5 a变化率效果最好,其拟合R2为0.956,RMSE为0.664 t/(hm^(2)·a),预测结果中RMSE为2.285 t/(hm^(2)·a);纹理因子在高山松地上生物量变化量建模中贡献最大。采用遥感因子变化率构建的高山松地上生物量动态变化估测模型,提高了生物量变化的估测精度,可为森林地上生物量的动态估测研究提供参考。

开发初期钻井工程定额周期修正方法分析——以塔里木盆地顺北地区钻井为例

顺北油气田为受断裂控制的特深碳酸盐岩断溶体油藏,是中石化在塔里木盆地新地区、新领域、新类型获得的重大油气突破。文章归纳总结中石化系统内部关于新井钻井周期预测方法特点,按照定额周期法预测钻井周期运行中存在的问题,分析并确定影响钻井周期变化的主要因素,提出解决油田开发初期定额周期与实际周期差异的方法,确保钻时定额的长期适用性。

Finite time thermodynamics analysis and research of pulsating heat pipe cold storage device

Phase change energy storage technology can effectively solve the energy mismatch in space and time.There are many disadvantages of phase change materials(PCMs),such as high supercooling,phase separation and poor heat transfer performance.As a new type of heat exchange structure,pulsating heat pipe has the advantages of simple structure,high heat transfer coefficient and good economic behavior.The system efficiency can be greatly improved by using pulsating heat pipe combined with cold storage technology.A set of pulsating heat pipe type cold storage device is developed,the finite time thermodynamic analysis is carried out,and the correlation between heat pipe efficiency and power is established.The three-dimensional physical model of pulsating heat pipe is simulated and verified by experiments.The experimental results show that in the cold storage stage,with the increase of the filling rate,the greater the pressure is,the better the heat transfer effect is;in the cold release stage,with the decrease of the filling rate,the smaller the pressure is,the better the heat transfer effect is.

基于踏板力和力变率的离合器操纵舒适性评价

文章针对人们对汽车舒适性要求的提高,从踏板力和行程的角度出发,分析踏板力及力变率对汽车离合器操纵舒适性的影响;通过分析离合器操纵机构,利用操纵过程中异点数量、踏板力与踏板行程线性度以及力变率对操纵舒适性进行评价,并建立了相应的评价模型和客观评价标准;最后通过实验数据验证了评价标准的合理性、可行性。