Understanding the Evolution and Socio-Economic Impacts of the Extreme Rainfall Events in March-May 2017 to 2020 in East Africa

This study aimed at assessing the evolution, distribution and the socio-economic impacts of extreme rainfall over East Africa during the March, April and May (MAM) rainfall season focusing on assessing the trends and contribution of MAM rainfall in mean annual rainfall across the region. It employed Principal Component Analysis (PCA) methods to capture the patterns and variability of MAM rainfall. The PCA results indicated that the first Principal Component (PC) describe 17% of the total variance, while the first six PCs account only 53.5% of the total variance in MAM rainfall, underscoring the complexity of rainfall forcing factors in the region. It has been observed that MAM rainfall accounts about 30% - 60% of the mean annual rainfall in most parts of the region, signifying its importance in agriculture, water, energy and other socio-economic sectors. MAM has been characterized by increasing variability with varying trend patterns across the region. The MAM rainfall trend is not homogeneous across the region;some areas are experiencing a slight decreasing rainfall trend, while other areas are experiencing a slight increasing rainfall trend. The observed trend dynamics is consistent with the global trend patterns in precipitation as depicted in recent Intergovernmental Panel on Climate Change (IPCC) reports. Over the last five years MAM rainfall season have been characterized by record-breaking extremes. On 8th May 2017, Tanga and Mombasa meteorological stations recorded 316 mm and 235.1 mm of rainfall in 24 hours respectively, which are the highest amounts for these respective stations, since their establishment. Record highest 24 hours rainfall amounting to 134.9 mm and 119.4 mm were also observed at Buginyanya and Kawanda meteorological stations in Uganda on 18th March 2018 and 7th May 2020. On 6th May 2020, Byimana meteorological station in Rwanda, also observed 140.6 mm of rainfall in 24 hours, the highest since its establishment. These extremes have caused multiple losses of life and property, and severe damages to infrastructure. Unfortunately, the frequency and intensity of these extremes are projected to increase under a changing regional climate patterns. It is therefore important that more studies are carried out to enhance understanding about the evolution, dynamics and predictability of these extremes in East Africa region.

HVDC换流阀故障特性分析及直流侧100Hz谐波计算方法研究

直流保护的正确动作对交直流大电网的安全稳定运行具有重要意义。为了探究换流阀故障特性以及阀故障导致直流侧100 Hz谐波分量产生机理和计算方法,首先分别对整流器阀和逆变器阀误开通故障和不开通故障时的通断特性和换流器的开关函数特性进行理论分析;其次给出了换流器序分量开关函数模型,在此基础上分析了阀故障导致直流侧产生100 Hz谐波分量的机理,并提出了具体的计算方法;最后基于贵广-Ⅱ回HVDC系统详细模型对该分析方法进行了仿真验证。结果表明,换流阀导通逻辑顺序的改变引起直流侧产生100 Hz谐波分量,且关于100 Hz谐波分量的计算方法能满足工程实际计算要求,为进一步研究直流系统100 Hz保护提供理论分析基础。

桑椹保健食醋的开发与研制

简述了桑椹的营养成分和生理功能,以大米为原料、桑椹为辅料,采用酶法液态混合发酵,压榨后加蜂蜜调配,得到桑葚保健食醋。成品具有营养丰富、功能性好、风味独特等特点。

超高压对刺参泡发及其品质的影响

本文以干制刺参为原料研究了超高压处理过程中,不同压力、温度及保压时间对刺参的持水力和质构的影响,并比较水发刺参和超高压处理刺参主要功能成分(胶原蛋白和海参多糖)的变化。结果表明,压力对刺参持水力的影响呈先增大后减小的趋势,压力为300 MPa处理时持水力最大;随着温度的升高,持水力不断增大,但是当温度升高的一定程度时,持水力基本保持不变;另外,随着保压时间的延长,持水力先增大后减小,保压时间为10min处理刺参持水力达到最大。采用300MPa,60℃,10 min处理刺参,硬度、黏附性、咀嚼性最大,此时刺参的质构最好,口感最佳。超高压处理对刺参的功能成分影响不大,但与鲜刺参相比,多糖含量和胶原蛋白的含量差异较小;与水发刺参相比,多糖和胶原蛋白含量均明显提高,说明超高压处理能够减少有效成分的损失。

永磁直线同步电动机磁阻力端部分量的解析建模

磁阻力造成永磁直线同步电动机的推力波动,产生振动和噪声,尤其是电机工作在速度或位置控制的低速区时,控制性能进一步恶化。在初、次级不完全耦合区域,采用样条函数对永磁直线同步电动机磁阻力的端部分量的有限元数据进行插值。插值结果与有限元分析结果一致。解析结果为永磁直线同步电动机的状态方程建模提供依据。

两个超越亚纯函数复合的动力学性质

讨论了两个超越亚纯函数复合的动力学性质,推广了若干已知结果.

媒体资产管理系统概述

媒体资产管理系统的出现解决了当前存储和管理的一些迫切问题,也为将来的系统升级和电视台数字化系统的融合提出了全新的解决方案。文章对媒体资产管理系统做了概述。

中国古代建构件的意义

文章将中国古代建构件纳入符号学、语言学的话语体系,尝试进行一种建筑语义学研究,追问建筑的本质。作者认为,中国建筑中数──象,象征语义系统是一套复杂的象──天/地/人对应的数术观念系统,也是符号系统,构成了中国古建筑数与象互证阐释的语义内涵。