考虑季节差异性的不同时间尺度含风电系统旋转备用优化研究

考虑风电出力和系统负荷的季节差异性较大,同时考虑风电出力预测误差和负荷预测误差随时间尺度的缩短而减小和电力系统旋转备用容量配置离不开机组组合的特点,本文建立考虑季节差异性下的不同时间尺度协调机组组合的含并网风电的电力系统旋转备用容量配置的模型。针对各个季节的风电出力和负荷变化特点,采用不同时间尺度协调机组组合的方法,对各个季节的场景进行分析,得出不同季节条件下的旋转备用优化方案。

利用大数据有的放矢防治地区和季节差异性产科疾病

21世纪是大数据的时代。大数据技术为科研提供了一种新的研究方法,由以往的假设驱动向数据驱动转变。利用大数据技术,对海量数据进行数据发掘、比较、聚类分析、相关性分析等,探索其中的规律,直接提出实验假设或得出可靠的实验结论。该文阐述地区性和季节性疾病的特点,以及大数据在疾病防控方面的作用;如何利用大数据思维研究地区和季节差异性产科疾病;如何利用大数据技术,有的放矢防治地区和季节差异性产科疾病。

园林绿化中不同植物的季节差异性搭配种植

随着社会的不断发展,城市的绿化建设也在快速发展。但是在绿化建设过程中,除了要考虑施工工期与建设需求等原因外,还必须考虑不同植物的季节差异性搭配种植。因此,在园林绿化过程中,施工人员与养护人员必须要对不同植物的季节差异性搭配种植技术非常了解与熟悉。基于此,从不同植物的季节差异性搭配种植方面入手,探讨其要点。

浅析铜、钼矿季节性指标波动影响因素及优化

本文对内蒙古乌奴格吐山铜钼矿(以下简称乌山)铜、钼矿季节性指标波动的影响进行技术调查分析与优化。通过全方面的技术调查研究发现:选矿回水水质、季节气候及矿石性质变化与选矿指标有直接关系,通过一系列措施优化,最终实现铜、钼精矿冬、夏季季节差互含品位较前三年钼精矿中含铜降低0.30%,铜精矿中含钼降低0.06%,实现增效1380.95万元。

季节变动的测定和季节预测

一、开展商情预测必须研究季节变动季节变动是指某些社会经济现象受自然因素和社会因素的影响,在一年内随着季节的更换而引起的比较有规律性的变动。市场上大部分商品属于常年生产,常年消费,但是,粮、棉、茶、麻等多数农产品,由于受自然条件的影响,是季节生产,常年消费。如蛋类、乳类春秋两季产量较高,夏冬两季产量较低。瓜果蔬菜多是季节生产,季节消费,如西瓜只在夏季生产,夏季消费。有些商品,如汗衫、背心、绒线等,由于季节变化的影响,属于常年生产,季节消费。有些即使是常年生产、常年消费的日用商品,也由于社会条件的影响。

电力市场环境下的典型产业月用电负荷预测分析

将市场竞争引入电力系统,企业竞争性得到提高,资源利用效率将得到改善。准确的月负荷预测可以提高电力系统的社会效益和经济效益,而负荷预测误差风险直接影响供电的安全性和稳定性。本文考虑到季节成分对月负荷预测的影响,基于季节变差以及季节比例理论建立短期负荷预测的指数平滑模型,并对月负荷原始数据进行预测。通过对蒙东电力的算例分析验证了本文所提出方法的合理性和可行性。

太湖西部宜溧河水系水质问题诊断

为阐明宜溧河水系的水质问题,采用现场采样和数据分析方法对宜溧河水系水质问题进行诊断,并分析了其季节差异性和空间差异性。

Trends in Temperature and Precipitation Extremes over Circum-Bohai-Sea Region,China

Trends in temperature and precipitation extremes from 1961 to 2008 have been investigated over Circum-Bohai-Sea region, China using daily temperature and precipitation data of 63 meteorological stations. The re- suits show that at most stations, there is a significant increase in the annual frequency of warm days and warm nights, as well as a significant decrease in the annual frequency of cold days, cold nights, frost days, and annual diurnal tem- perature range （DTR）. Their regional averaged changes are 2.06 d/1 0yr, 3.95 d/10yr, -1.88 d/10yr, -4.27 d/10yr, -4.21 d/10yr and -0.20℃/10yr, respectively. Seasonal changes display similar patterns to the annual results, but there is a large seasonal difference. A significant warming trend is detected at both annual and seasonal scales, which is more contributed by changes of indices defined by daily minimum temperature than those defined by daily maximum tem- perature. For precipitation indices, the regional annual extreme precipitation displays a weak decrease in terms of magnitude and frequency, i.e. extreme precipitation days （RD95p）, intensity （RINTEN）, proportion （RPROP） and maximum consecutive wet days （CWD）, but a slight increase in the maximum consecutive dry days （CDD）, which are consistent with changes of annual total precipitation （PRCPTOT）. Seasonally, PRCPTOT and RD95p both exhibit an increase in spring and a decrease in other seasons with the largest decrease in summer, but generally not significant. In summary, this study shows a pronounced warming tendency at the less rainy period over Circum-Bohai-Sea region, which may affect regional economic development and ecological protection to some extent.

Response of Lakes to Climate Change in Xainza Basin Tibetan Plateau Using Multi-Mission Satellite Data from 1976 to 2008

Changes in the lake areas of Xainza basin in the past 33 years （1976 to 2008） were studied using Landsat data from Multispectral Scanners （1973- 1977）, Thematic Mapper （1989-1992, 2007-2009）, and Enhanced Thematic Mapper Plus （1999-2002）. The results indicated that lakes in the study area evidently expanded from 1976 to 2008, with total expansion of 1512.64km2. The mean annual air temperature presented an upward trend with certain fluctuations from 1966 to 2008. The air temperature rise rates in the cold season （o.31~C/loa） were higher than those in the hot season （0.24℃/1oa）, in the Xainza station example. Precipitation exhibited evident seasonal differences. Mean annual precipitation in hot season is 281.48 mm and cold season is 32.66 mm from 1966 to 2008 in study area. Precipitation in the hot season was the major contributor to the increase in annual precipitation. Grey relational analysis （GRA） was used to study the response of lake areas to climatic factors. The mean air temperature and precipitation were selected as comoared series, and the lake areas were regarded as the reference series. The grey relational grade （GRG） between compared series and reference series were calculated through GRA. The results indicated that changes in lake areas were mainly affected by climatic factors in the hot season. Lakes in this region were classified into three grades, namely, Grades I, II, and III according to the recharge source and elevation. The GRGs of each series varied for different grade lakes： the area of Grade III lakes were the most relevant to the hot season factors, the GRGs of precipitation and air temperature were 0.7570 and 0.6606; followed by the Grade II lakes; Grade I lakes were more sensitive to the air temperature.

Monthly variation in the fat content of anchovy (Engraulis japonicus) in the Yellow Sea: implications for acoustic abundance estimation

Anchovy is a key species in the Yellow Sea ecosystem. An accurate estimate of anchovy abundance is vital for the management of the anchovy stock and measurement of the ecosystem response to changes in anchovy abundance. However, the acoustic fish abundance estimate may be biased by 30%-40% if the fat-content induced target strength variation is not taken into account. We measured the monthly variation in the fat content of anchovy (Engraulis japonicus) in the Yellow Sea, and evaluated the potential effect of variation in fat content on the acoustic assessment of anchovy abundance. The fat content of anchovy varied seasonally, with two maxima and two minima in a year. The highest fat content (14.75%) was measured in the pre-spawning period in May, and the lowest fat content (2.48%) was measured during the post-spawning period in October. Fat content appeared to correlate with water content, but not body size. Assuming that the target strength is decreased by 0.2dB for every 1% increase in fat content, the seasonal difference in the target strength of anchovy may be as high as 2.45 dB. Given this, the acoustic abundance estimate may be biased by between 43% and 76%. Our results highlight the need for more information on the changes in fat content of fishes whose abundance is estimated by acoustic surveys.

Spatio-temporal distribution of net-collected phytoplankton community and its response to marine exploitation in Xiangshan Bay

To explore the spatial-temporal distribution of the phytoplankton community and evaluate the combined effects of marine resource exploitation, net-collected phytoplankton and physical-chemical parameters were investigated in the Xiangshan Bay during the four seasons of 2010. A total of eight phyla, 97 genera, and 310 species were found, including 232 diatom species, 45 dinoflageUate species and 33 other taxa. The phytoplankton abundances presented a significant （P〈0.001） seasonal difference with the average of 60.66x104 cells/m3. Diatoms （mainly consisting of Coscinodiscus jonesianus, Cerataulina pelagica, Skeletonema costatum, and genus Chaetoceros） dominated the phytoplankton assemblage in all seasons. We found great spatio-temporal variation in community composition based on the multidimensional scaling and similarity analysis. Canonical correspondence analysis show that temperature, nutrition, illumination, and salinity were the main variables associated with microalgal assemblage. Compared with the previous studies, an increase in phytoplankton abundance and change in the dominant species coincided with increased exploitation activities in this bay （e.g. operation of coastal power plants, intensive mariculture, tidal fiat reclamation, and industrial and agricultural development）. The present findings suggest that the government should exercise caution when deciding upon developmental patterns in the sea-related economy.

全球LNG市场特征和趋势分析及对我国的启示

在能源转型大背景下,全球天然气需求表现强劲。其中液化天然气(LNG)作为打通天然气地域限制的重要一环,表现尤为活跃。2018年全球LNG市场出现了“牛夏熊冬”,运力局部时段偏紧,短合同数目明显增加,合约价格斜率有所反弹,传统的20年期长约再次回归市场,更多项目开始倾向于在没有签订固定合同的条件下做出最终投资决定等新特点。同时,也呈现了中国和印度需求将快速攀升,日本需求缓慢下滑,韩国需求增长缓慢,亚洲新兴市场快速崛起等新趋势。长期看,东南亚、南亚等新兴市场的崛起一定程度上将平抑中长期亚洲市场的季节性峰谷差,也会令LNG现货/短约的定位由应对季节性波动转向一种常规的天然气商品。在此大趋势下,我国可继续加大国内油气资源勘探开发力度,提升能源安全保障基础水平;加大调峰储备体系建设,有效应对国际市场短期波动;不断扩大进口来源,积极开展国际合作。

Extended-range prediction of a heat wave event over the Yangtze River Valley:role of intraseasonal signals

The authors previous study reported the important role of extratropical intraseasonal oscillation(ISO)on the occurrence of a typical heatwave event over the Yangtze River Valley.Based on the ECMWF subseasonal reforecast database,this follow-up study evaluates the extended-range prediction skill of the heatwave event and further unravels the close link between the ISO and extended-range prediction of the event.With a two-week lead time,this heatwave event fails to occur in the reforecast because the predicted surface temperature is signi cantly underesti-mated.More detailed analysis demonstrates that the biases for both the intensity and the location of the warming region are primarily attributable to the inaccurate extratropical intrasea-sonal traveling signals.This work strongly indicates that accurately capturing the extratropical intraseasonal signal from the Eurasian continent is indispensable for extended-range prediction of East Asian extreme heatwave events.

Decadal Variability of Global Ocean Significant Wave Height

This paper presents the long-term climate changes of significant wave height(Hs) in 1958–2001 over the entire global ocean using the 45-year European Centre for Medium-Range Weather Forecasts(ECMWF) Reanalysis(ERA-40) wave data. The linear trends in Hs and regional and seasonal differences of the linear trends for Hs were calculated. Results show that the Hs exhibits a significant increasing trend of about 4.6 cm decade-1 in the global ocean as a whole over the last 44 years. The Hs changes slowly during the periods 1958–1974 and 1980–1991, while it increases consistently during the periods 1975–1980 and 1995–1998. The Hs reaches its lowest magnitude in 1975, with annual average wave height about 2 m. In 1992, the Hs has the maximum value of nearly 2.60 m. The Hs in most ocean waters has a significant increasing trend of 2–14 cm decade-1 over the last 44 years. The linear trend exhibits great regional differences. Areas with strong increasing trend of Hs are mainly distributed in the westerlies of the southern Hemisphere and the northern Hemisphere. Only some small areas show obvious decreasing in Hs. The long-term trend of Hs in DJF(December, January, February) and MAM(March, April, May) is much more stronger than that in JJA(June, July, August) and SON(September, October, November). The linear trends of the Hs in different areas are different in different seasons; for instance, the increasing trend of Hs in the westerlies of the Pacific Ocean mainly appears in MAM and DJF.

Improved EOF-based bias correction method for seasonal forecasts and its application in IAP AGCM4.1

An effective improvement on the empirical orthogonal function(EOF)–based bias correctionmethod for seasonal forecasts is proposed in this paper,by introducing a stepwise regression method into the process of EOF time series correction.Using 30-year(1981–2010)hindcast results from IAP AGCM4.1(the latest version of this model),the improved method is validated for the prediction of summer(June–July–August)rainfall anomalies in Southeast China.The results in terms of the pattern correction coefficient(PCC)of rainfall anomalies shows that the 30-year-averaged prediction skill improves from 0.01 to 0.06 with the original correction method,and to 0.29 using the improved method.The applicability in real-time prediction is also investigated,using 2016 summer rainfall prediction as a test case.With a PCC of 0.59,the authors find that the new correction method significantly improves the prediction skill;the PCC using the direct prediction of the model is?0.04,and using the old bias correction method it is 0.37.

TREND OF PRECIPITATION VARIATION IN HUBEI PROVINCE SINCE THE 1960S

Through linear regression analysis to the trend of annual,seasonal and monthly precipitation of 72 meteorological stations in Hubei Province from 1961 to 1995,it is revealed that: 1) annual precipitation was increasing by 61.0mm/10a in the eastern part of Hubei (112°E as a dividing line) and decreasing by 34.9mm/10a in the western part; 2) precipitation in winter and summer (January,February,March,June and July) was increasing in almost whole province which usually with non-uniformity of precipitation distribution from the south to the north. The precipitation in spring,autumn and winter (April,September,November and December) was decreasing in most of the areas which usually with non-uniformity of precipitation distribution from the east to the west. March and December were transition periods between two spatial distribution patterns mentioned above; 3) the eastern part of Hubei has beome one of precipitation increasing centers in China. The results was consistent with the trend that more frequent flood and drought events happened in Hubei Province which are more different in spatial and temporal scales.

Variability of Surface Sensible Heat Flux over Northwest China

The present study documents the variability of surface sensible heat flux over Northwest China using station observations for the period 1961 2000.It is found that the afternoon and nighttime sensible heat flux variations are remarkably different.The variability of the instant flux in the afternoon is much larger than in the nighttime.The afternoon and nighttime flux anomalies tend to be opposite.The diurnal and seasonal dependence of sensible heat flux variations is closely related to the diurnal cycle of mean land-air temperature difference.The relationship of sensible heat flux with land-air temperature difference based on the instant value differs from that based on the daily mean.The present study indicates the importance for the models to properly simulate mean land-air temperature difference and its diurnal and seasonal variations in order to capture surface sensible heat flux variability over Northwest China and predicts its plausible impacts on climate.

Seasonal Differences in Live Foraminiferal Densities： Case Studies from Tropical and Temperate Intertidal Environments

Statistically significant differences （when p 〈 0.05 using the permutation t-test） among Live Foraminiferal Densities （LFDs） recovered in August, November, March and May were detected at tropical Caroni swamp, Claxton bay （Trinidad）, temperate Cowpen marsh and Brancaster marsh （U.K.）. The monthly mean LFDs of the foraminiferal metacommunities （all stations）, assemblages （groups of stations defined by cluster analysis）, and the agglutinated and calcareous specimens within each were compared separately. The LFDs of the Caroni swamp metacommunity did not fluctuate significantly among months, but significantly higher abundances of agglutinated specimens occurred in the upper assemblage in March; and calcareous specimens in the lower assemblage in November. At Claxton bay, monthly LFDs of the metacommunities and assemblages did not vary significantly, but calcareous and agglutinated species within each favoured dry （March and May） and wet （August and November） months respectively At the temperate marshes, significantly higher LFDs of the metacommunities and assemblages were recorded in warmer months. August blooms of the Cowpen marsh metacommunity was attributed to agglutinated specimens in the upper assemblage, and calcareous specimens in the lower assemblage. May blooms of the Brancaster marsh upper assemblage were attributed to calcareous specimens, but there were no seasonal blooms of the lower assemblage.

Community Structure and Seasonal Variation of Soil Arthropods in the Forest-Steppe Ecotone of the Mountainous Region in Northern Hebei,China

Soil fauna have been receiving more and more attention because they play an important role in nutrient cycling.However,there is a lack of information on soil arthropods in the forest-steppe ecotone in the mountainous region of northern Hebei,which makes it difficult to meet the need of protecting biodiversity in this area.Soil arthropod communities were investigated in the forest-steppe ecotone in northern Hebei province to provide basic information on changes in mountain soil fertility,which could promote the development of soil arthropod communities in mountain ecotones.From the preliminary identification,a total of 7994 individual soil arthropods were collected,which belonged to 25 groups,6 classes and 24 orders.Acarina,Hymenoptera and Collembola were the dominant groups in the ecotone.The number of Acarina was higher than Collembola,and this phenomenon was obviously different from other areas in the same climate zone.The increased abundance of rare groups in the Forest zone with the richer vegetation,higher arthropod abundance and more substantial litter depth,could be interpreted as a reaction to the suitable soil environment and food supply.And these rare groups were sensitive to environmental changes,which could be regarded as biotic indicators for evaluating soil quality.The analysis of community diversity showed that the abundance index (d),the Shannon-Wiener index (H'),the evenness index (J) and the density-group index (DG) were significantly higher in the forest zone,lower in the forest-steppe zone,and lowest in the meadow-steppe zone.Seasonal variations in community composition correlated with changes in average air temperature and precipitation in this ecotone.Groups and individuals of soil arthropod communities in the three zones were present in greater numbers in the middle of the rainy season than in the early or late periods of the rainy season as a whole.At the same time,seasonal changes in soil arthropod communities from different plots were also influenced by habitat condition.

Yield Stability and Late Blight Resistance Analysis among Potato Clones Bred with Quantitative Resistance

Thirteen promising clones from population B3C2 potato genotypes （bred for quantitative resistance to late blight） obtained from the International Potato Center and three control cultivars were evaluated for four planting dates within two cropping seasons at Kalengyere Research Station in Southwestern Uganda in order to determine performance and yield stability. The analysis of variance of the relative area under disease progress curve （rAUDPC） revealed significant difference （P 〈 0.001） among genotype x planting date interaction, and significant difference （P 〈 0.001） among genotypes x fungicide treatments x planting date interaction. The analysis of variance （ANOVA） of yield revealed also significant difference among genotypes x planting date interaction and significant difference （P 〈 0.05） among genotypes x fungicide treatments x planting date interaction, showing the variable response of genotypes and the need for stability analysis. The additive main effects and multiplicative interactive （AMMI） statistical model showed that the most stable and high yielding genotypes were 396038.107, 396026.103 and 393280.82. The cultivars Victoria, Nakpot 5 and Cruza recorded low yields （below the average）, but Nakpot 5 was generally more variable, and is therefore highly adaptable to some environments.