一种面向配网设备的在线红外测温系统设计

设计了一种面向配网设备的在线红外测温系统,阐述了该系统的设计思路及工作原理,介绍了系统工作流程;利用该系统对一台标准热源进行温度测量,验证其测量重复性;同时,与目前电力系统现场设备红外测温领域广泛应用的红外测温仪进行对比分析,验证该红外测温系统的测量有效性及优势,为系统后续深化应用提供参考。

“屏阅读”时代大学生信息素养教育创新:内涵演变、存在问题与框架构建

“屏阅读”时代,日益严重的“屏阅读”危机使大学生深陷于“我的泛滥”“词的破碎”“物的牢笼”之中,面临着手机沉溺、批判性思维欠缺、身心割裂的困境。为改善大学生“屏阅读”行为,提升大学生新信息素养水平,亟需创新大学生信息素养教育模式。在内容分析、网络调研的基础上,揭示了“屏阅读”时代大学生信息素养教育存在的问题,并以“元素养”理论为依据,构建“屏阅读”时代大学生信息素养教育框架。此研究为大学生信息素养教育创新提供了一种新思路。

蒙古西北部Tolbo湖沉积物粒度敏感组分记录的全新世风沙活动

作为全球主要的粉尘源区之一,亚洲中部干旱区全新世环境变化备受关注,但目前仍缺乏连续的风成沉积记录。本文利用蒙古西北部Tolbo湖岩芯(TB19-A,332 cm)沉积物,在AMS 14 C定年和粒度分析基础上,采用对数正态分布函数拟合及粒级-标准偏差相结合的方法分离出沉积物中风成组分以重建区域风沙活动历史。结果显示,Tolbo湖沉积物中值粒径为15~84μm和大于84μm的组分分别是区域尘暴和局地风沙活动的良好指标。蒙古西北部地区末次冰消期晚期(13.7511.6 cal ka BP),Tolbo湖流域内有较强的局地风沙活动,可能与YD寒冷事件有关。全新世以来,流域内局地风沙活动与蒙古西北部区域尘暴活动的变化具有一致性,具体表现为:早中全新世风沙活动总体较弱,其中9.78.6 cal ka BP和76 cal ka BP为区域尘暴较强时段;5 cal ka BP之后局地风沙活动与区域尘暴强度显著增加,直至0.7 cal ka BP两者均维持在较高水平;0.3 cal ka BP以来区域尘暴活动再次增强。蒙古西北部与中国北方公海、博斯腾湖记录的尘暴历史具有一致的变化趋势,反映了与西伯利亚高压相联系的大气环流对于干旱区大范围风沙活动的影响。晚全新世风沙活动的增强可能还与冬季太阳辐射的增加有关,最近300年来强烈的区域尘暴活动除了自然因素外,可能还叠加了人类活动的影响。

消解阅读焦虑,培育时代阅读新人

数字时代,信息泛滥成灾,碎片化阅读、手机沉溺、娱乐至死等阅读症候,使阅读者处于与外部世界割裂、内外不平衡、身心不和谐、知识结构碎片化的焦虑状态。构建身心和谐、全面发展的时代阅读新人已成为全民阅读亟需解决的重要课题。“学以成人”的哲思关注人的发展和建构,为时代阅读新人的培育提供了新思路。文章运用“学以成人”理论探究数字媒介转型和社会转型期阅读焦虑者面临的“三重”困境,并尝试提出干预对策。本研究是对全民阅读推广理论和阅读学理论的丰富。

柴达木盆地托素湖不同位置岩芯沉积物指标对比及其环境意义

湖泊不同位置岩芯沉积物相同代用指标的变化是否一致对于重建可靠的区域气候变化历史至关重要.目前多数研究仅利用深水区单一的沉积岩芯来反演区域的气候环境变化,对于不同位置岩芯重建结果的异同尚缺乏研究.本文选择托素湖不同位置、不同水深的4根短钻岩芯沉积物,在放射性核素(210 Pb和137 Cs)定年的基础上,对比分析各岩芯沉积物粒度、碳酸盐含量等代用指标的变化情况.结果显示,湖泊内相近的沉积岩芯沉积物粒度变化相似,但相距较远的岩芯之间粒度变化差异较大;浅水区的沉积物粒度(粒径或组分含量)在短时间尺度上变化很大,而深水区的沉积环境比较稳定,在百年尺度上的变化不明显;有机质与碳酸盐含量总体变化趋势一致且有较好的相关性,表明碳酸盐可能受到湖泊生产力的影响.碳酸盐含量、碳酸盐氧同位素(δ18 O)和TL06孔孢粉的A/C比值变化基本一致,反映的有效湿度变化与同期气象记录的相对湿度一致,但与降水量和蒸发量的变化不一致.因此,托素湖粒度指标仅指示不同位置钻孔沉积环境状况,与气候变化的关系并不明显,用碳酸盐及其同位素等地球化学指标恢复区域气候变化历史更可靠.

湛江新机场航站楼屋盖结构分区等效静风荷载研究

对湛江新机场航站楼屋盖结构的屋面风荷载特性和时域法风振响应特性进行研究,分别采用分区风振系数法、分区多目标法和分区约束多目标法计算屋盖结构的等效静风荷载。结果表明:屋盖表面平均风压主要表现为负压,在垂直于风向角的屋盖迎风前缘负压最大,距离迎风前缘越远风压逐渐减小,脉动风压变化规律与平均风压基本相同。屋盖结构最大风振响应处主要位于屋面悬挑区域,结构设计时需重点关注该区域的响应。分区风振系数法等效风压分布合理,但等效响应整体误差大。以少量分区脉动风压为荷载基本向量的分区多目标法等效响应整体精度高;考虑约束方程的分区约束多目标法等效响应整体精度有所下降,但分区风压变化均匀连续,等效风压分布合理,便于工程应用。

考虑多源互补特性的孤岛供电故障恢复方法

针对光伏、风机等间歇性电源作为配电系统供电恢复电源的情况,首先提出电源系统互补联合运行判据,将具有互补特性的电源进行联合运行;然后提出一种结合Floyd算法与Prim算法、考虑电源最短路径的孤岛划分方法;在此基础上,设计了考虑多源孤岛互补特性的故障恢复流程。算例结果表明,所提出的考虑多源孤岛互补特性的供电故障恢复方法,可以有效减小间歇性电源的出力波动对孤岛恢复容量的影响,能够恢复更多负荷,提升恢复效果。

Effects of climate change and human activity on lake shrinkage in Gonghe Basin of northeastern Tibetan Plateau during the past 60 years

Changes in the status of freshwater resources are a topic of major global, regional and local concern. This is especially so in the arid and semi-arid regions of China, where shortage of water resources plays a crucial role in limiting sustainable socioeconomic development, as well as in sustaining natural ecosystems. Recent climate change, as well as the effects of localized human activity, such as the use of water for irrigation agriculture, may have significant effects on the status of the water resources in the region. Here, we report the results of a study of changes in the areas of lakes in Gonghe Basin, northeastern Tibetan Plateau of China, over the last 60 years. The data were acquired from optical satellite images and demonstrate that the total water area of lakes in Gonghe Basin decreased significantly from the 1950s to 1980s. The cause is ascribed mainly to human activity including exploitation of farmland, against a background of increasing population; in addition, climatic data for the region demonstrate a minor drying trend during this period as the temperature increased slightly. After the construction of several reservoirs, significant amounts of water were redistributed to promote irrigation agriculture and we conclude that this caused a significant shrinkage of the natural lakes. However, both the area of farmland and the population size remained approximately constant after 1990. We conclude that the variation of the total area of lakes during the second period was mainly controlled by climatic factors （precipitation and temperature）. As the regional temperature reached a new high, the area of some of the lakes decreased sharply before finally maintaining a relatively steady state. We emphasize that anthropogenic climate change and human activity have both significantly influenced the status of water resources in the arid and semi-arid regions of China.

广州空港会展中心复合张弦桁架结构体系选型与分析

广州空港会展中心标准展馆利用结构参数化工具对多种类型展馆结构进行选型对比,综合建筑效果、使用需求和经济指标,首次在展馆内采用复合张弦桁架结构体系。对复合张弦桁架结构进行非线性设计分析、双非线性稳定分析、防连续性倒塌分析和不平衡吊挂荷载分析,结果显示,结构各项计算指标均满足规范要求,并具有足够安全冗余度。高风压作用下拉索可维持足够的索力并且不松弛,屋面变形可控。相关索节点传力清晰,背锚节点有利于现场张拉施工。下弦拉杆在初始态到全荷载态的全受力过程中拉压变向,下弦杆受力满足不同荷载状态需求。复合张弦桁架结构体系满足多种施工方式选择,张拉施工快捷、方便,地坪、屋盖施工互不干扰。复合张弦桁架结构在沿海高风压地区具有优越的受力性能和建筑表现力。

基于因果关系分析的短期负荷预测方法研究

随着高比例可再生能源和电力市场的快速发展,电力系统不确定性增大。为提高市场环境下负荷预测精度,提出一种基于因果关系分析的短期负荷预测方法。首先,采用灰色关联度分析法量化气象因素和市场因素与负荷的相关性;然后,采用最优模态分解法对负荷模态分解,利用Granger因果分析法将影响因素与模态子序列进行匹配;最后,对子序列分别采用差分自回归移动平均(ARIMA)模型和双向长短时记忆(Bi-LSTM)神经网络模型进行预测,将预测结果叠加得到短期负荷预测结果。仿真结果表明,所提方法的预测精度可达到92%,验证了方法的准确性和有效性。

温室穹顶结构大尺度网格优化研究

某温室花园穹顶屋面曲率变化大、网格尺度大,原建筑方案网格尺寸大小不一,网格均匀性连续性较差。在原网格的基础上进行曲面重建,分别采用曲面参数域细分法、气泡法以及曲面近似展开贴面法对大面温室网格进行划分,采用自适应三角形网格推进法对连桥网格进行划分。结果表明:曲面细分法网格流畅性好,网格均匀性较差;气泡法网格均匀性较好,网格流畅性差,网格存在局部奇异点;基于曲面近似展开的贴面法网格,大面网格均匀性及流畅性均有明显改善,网格无奇异点,对于曲率变化较大的大尺度屋盖,可采用该方法进行网格划分。

Paleohydrological Changes in the Western Tibetan Plateau over the Past 16,000 years Based on Sedimentary Records of n-Alkanes and Grain Size

Both monsoons and westerlies have exerted influence on climate dynamics over the Tibetan Plateau(TP) since the last deglaciation, producing complex patterns of paleohydroclimatic conditions. Diverse proxy records are essential to forge a robust understanding of the climate system on the TP. Currently, there is a general lack of understanding of the response of inland lakes over the TP to climate change, especially glacier-fed lakes. Paleohydrological reconstructions of such lakes could deepen our understanding of the history of lake systems and their relationship to regional climate variability. Here we use records of n-alkanes and grain size from the sediments of Bangong Co in the western TP to reconstruct paleohydrological changes over the past 16,000 years. The Paq record(the ratio of non-emergent aquatic macrophytes versus emergent aquatic macrophytes and terrestrial plants) is generally consistent with the variations in summer temperature and precipitation isotopes. The changes in grain-size distributions show a similar trend to Paq but with less pronounced fluctuations in the early-middle Holocene. The new data combined with previous results from the site demonstrate that: 1) Bangong Co experienced relatively large water-level fluctuations during the last deglaciation, with a steadily high lake-level during the early-middle Holocene and a decreasing lake-level in the late Holocene;2) The lake level fluctuations were driven by both high summer temperatures via the melting water and monsoon precipitation. However, the dominant factor controlling lake level changed over time. The lake-level history at Bangong Co deduced from the n-alkanes and grain-size records reveals the past hydrological changes in the catchment area, and stimulates more discussion about the future of glacier-fed lakes under the conditions of unprecedented warming in the region.

浅谈生命课堂背景下的高中英语自主学习课堂构建

阐述生命课堂的内涵。分析生命课堂背景下构建高中英语自主学习课堂的重要性。结合教学实例,探索生命课堂背景下高中英语自主学习课堂的构建策略,即吸引学生的注意力,让参与成为一种习惯;组织小组合作,培养学生的自主学习能力;及时捕捉生成资源,促进学生深度思考。认为在生命课堂背景下构建高中英语自主学习课堂,有助于达成课堂生成性教学的目的。

基于信号分离的电缆局放检测分析

针对传统高频电流法检测电缆局放存在的缺陷,提出采用基于信号分离技术的电缆局放检测方法的理论依据,并采用TechImp局部放电仪对一条电缆进行局放检测,以证明基于信号分离技术的电缆局放检测方法的可行性和优越性。

我国季风边缘区湖泊沉积记录的全新世亚洲夏季风衰退事件

亚洲夏季风是全球季风系统的重要组成部分,亚洲夏季风的变化对其控制区域自然生态系统的多样性和生态平衡,以及社会经济发展有重要的影响。本文选择位于现代亚洲夏季风边缘区对季风变化响应敏感的湖泊达连海为研究对象,基于陆生植物残体和全有机质的AMS14C定年建立了钻孔顶部24.6 m沉积物的年代框架,利用粒度指标重建了全新世研究区水文变化过程以及亚洲夏季风衰退事件序列。结果显示,沉积物中存在数层砂层,代表了湖泊低水位时期,进而指示了亚洲夏季风衰退事件。这些事件处在11.6~11.3 cal.ka B.P.、10.4~9.5 cal.ka B.P.、6.4~6.0 cal.ka B.P.、4.6~4.4 cal.ka B.P.、3.7~3.4 cal.ka B.P.、3.1~2.9 cal.ka B.P.以及2.0~0.9 cal.ka B.P.,可以发现中晚全新世以来亚洲夏季风衰退事件发生的频率显著增加。进一步与北半球高纬地区与低纬地区的气候突变事件记录对比显示,全新世百年-千年时间尺度上亚洲夏季风强度的变化与低纬ENSO活动存在密切的联系。

湖泊沉积物含水量和结构对XRF扫描结果影响的评估及校正--以西藏阿翁错为例

本研究利用XRF岩芯扫描仪对青藏高原西部的阿翁错湖泊沉积物进行高分辨率元素扫描。通过与传统X射线荧光光谱仪测试结果进行相关分析,对XRF元素扫描结果中常用元素的可靠性和准确性进行评估,并通过标准化多项式校正法、多元对数比校正法及标准化中位数校正法对其进行校正。结果表明,元素Ti和Fe的XRF岩芯扫描元素强度与传统XRF方法测试的元素含量显著相关,其结果可靠,能够反映元素的真实变化过程,无需对其校正。Al、Si和K元素强度受到岩芯含水量等因素的影响,Ca元素强度易受到岩芯裂隙的影响,在使用前需要对其进行校正。不同校正方法的校正结果对比表明,标准化多项式校正方法对湖泊沉积物中Al、Si、K和Ca元素强度的校正效果最好。当岩芯含水量变化较大造成岩芯表面出现裂隙等结构变化时,建议进行分段校正。

A 1000-year chironomid-based salinity reconstruction from varved sediments of Sugan Lake,Qaidam Basin,arid Northwest China,and its palaeoclimatic significance

A 1000-year high-resolution(～10 years) chironomid record from varved sediments of Sugan Lake,Qaidam Basin on the northern Tibetan Plateau,is presented.The chironomid assemblages are mainly composed of the relatively high-saline-water taxa Psectrocladius barbimanus-type and Orthocladius/Cricotopus,and the relatively low-saline-water taxa Procladius and Psectrocladius sordidellus-type.Variations in the chironomid fauna and inferred salinities suggest that over the last millennium,the Sugan Lake catchment has alternated between contrasting climatic conditions,having a dry climate during the period 990―1550 AD,a relatively humid climate during the Little Ice Age(LIA)(1550―1840 AD),and a dry climate again from 1840 AD onwards.At the decadal to centennial scale,a wet event around 1200―1230 AD,interrupting the generally arid period(990―1550 AD),and a dry event around 1590―1700 AD,punctuating the generally humid period(1550―1840 AD),are clearly documented.Trends in the chironomid-based salinity time series indicate a highly unstable climate during the LIA when salinity fluctuations were of greater magnitude and higher frequency.The effective moisture evolution in the Sugan Lake catchment during the last millennium reconstructed by chironomid analysis is in broad agreement with previous palaeo-moisture data derived from other sites in arid Northwest China(ANC).The LIA,characterized by generally humid conditions over the west-erly-dominated ANC was distinctly different from that in monsoonal China,implying an "out-of-phase" relationship between moisture evolution in these two regions during the past 1000 years.

Climatic changes documented by stable isotopes of sedimentary carbonate in Lake Sugan,northeastern Tibetan Plateau of China,since 2 kaBP

Lake Sugan at the northern edge of the Qaidam Basin was selected as the research object. The temporal se-quence of sedimentary cores retrieved from Lake Sugan since 2 kaBP was reconstructed using the 210Pb, AMS 14C and conventional 14C dating methods. Carbon and oxygen iso-topes of carbonate in the fine-grained lake sediments were analysed. Combined with the changes of δ 18O values of sur-face water and air temperature observation data in the study area, it might be thought that the δ 18O value of the carbon-ate indicates effective moisture, and the changes in δ 13C val-ues are related to annual freeze-up duration of the lake and indirectly indicate air temperature changes in winter half year. From the above, the sequence of climatic changes in the region since 2 kaBP was established. The climatic changes experienced five stages: Warm-dry climate during 0-190 AD; cold-dry climate during 190-580 AD; warm-dry cli-mate during 580-1200 AD (MWP); cold-wet climate during 1200-1880 AD (LIA); cold-dry climate during 1880-1950 AD; and climate warming since 1950s. The air temperature changes in winter half year reflected by carbon isotope since 2 kaBP are in good agreement with the historical literature records and other geologic records, which shows that the climate changes recorded by the stable isotopes from Lake Sugan since 2 kaBP are of universal significance.

The discovery of annually laminated sediments (varves) from shallow Sugan Lake in inland arid China and their paleoclimatic significance

Detailed examination of sedimentary cores retrieved from Sugan Lake in the northern Qaidam Basin of northwest China’s Tibetan Plateau reveal that fine laminated beddings form in the sediments where water depth exceeds 3 m. Seasonal surface sediments trapped at the bottom of the lake suggest that sediments deposited during summer and autumn are mainly light colored monohydrocalcites, while those deposited in winter are dark organic matter, indicating that varve layers form under modern limnological conditions. Continuous varve sediments comprising four types have accumulated in the upper 5.5 m of Core SG03I from the center of the lake. All types exhibit clear seasonality indicative of annual deposition. Varve counts correspondence with 210Pb dates on recent sediments in the upper core suggest the continuous varves of the upper 5.5 m of the core formed in the late Holocene (2670 a BP). The Sugan Lake varve sequence is the first demonstration of annually laminated sediments re-ported in arid western China.

Palaeovegetational and palaeoenvironmental changes since the last deglacial in Gonghe Basin, northeast Tibetan Plateau

Paleoenvironmental history in the monsoonal margin in the northeast Tibetan Pla- teau provides important clue to the regional climate. Previous researches have been limited by either poor chronology or low resolution. Here we present a high-resolution pollen record from a 40.92-m-long sediment core （DLH） taken from Dalianhai, a terminal lake situated in the Gonghe Basin, the northeast Tibetan Plateau for reconstructing the vegetation and climate history since the last deglacial on the basis of a chronology controlled by 10 AMS 14C dates on plant remains preserved in the core sediments. The pollen assemblages in DLH core can be partitioned into 6 pollen zones and each zone is mainly characterized by the growth and decline of tree or herb pollen percentage. During the periods of 14.8-12.9 ka and 9.4-3.9 ka, the subalpine arboreal and local herbaceous pollen increased, indicating the subalpine forest developed in the surrounding mountains and a desert steppe or typical steppe developed in Gonghe Basin under a relatively moister climate. During the periods of 15.8-14.8 ka, 12.9-9.4 ka and 3.9-1.4 ka, the forest shrank or disappeared according to different degrees of aridity, and the desert steppe degraded to a more arid steppe desert in the basin, indicating a dry climate. After 1.4 ka, vegetation type around Dalianhai was mainly dominated by steppe suggested by increased Artemisia. Our results suggested the climate history in this region was dry from 15.8-14.8 ka, humid from 14.8-12.9 ka and dry from 12.9-9.4 ka, after which the climate was humid during 9.4-3.9 ka, followed by dry conditions during 3.9-1.4 ka and humid conditions in the last 1.4 ka. The change of pollen percentage and the evolution of palaeovegetation in Dalianhai since the last deglacial were similar to those recorded in Qinghai Lake. The forest expanded in the mountains around Dalianhai during the Bol- ling-Aller^d period, shrank during the Younger Dryas and the early Holocene, then it devel- oped and reached its maximum in the mid-Holocene. During the late Holocene, the vegetation began to shrink till disappearance. However, the timing of forest expansion in the Holocene lagged behind that of Qinghai Lake, and this spatial heterogeneity was probably caused by the different forest species between these two places. The maximum of forest development in the mid-Holocene was inconsistent with the period of stronger summer monsoon in the early Holocene indicated by stalagmite records, the reason might be related to the complexity of vegetation response to a large-scale climatic change.