Seasonal Distribution Characteristics Research Articles

Seasonal Distribution Characteristics and Health Risk Assessment of Heavy Metals in Surface Water of Qingjiang River

In order to assess the health risks of heavy metals in surface water of Qingjiang River, surface water samples were taken at designed cross-sections of the river and analyzed for Cr, Cu, Zn, Pb, Cd, As, and Mn. Health risks from these heavy metals for adults and children in wet and dry seasons were compared by water environmental health risk assessment model of the USEPA. It found that the main excessive element is Mn, concentrating in the Danshui, Yantouxi, and Pingluoxi, the slightly excessive element is As, the concentration of Mn was above national standard, and it mainly distributed in Danshui, Yantouxi, and Pingluoxi, As was slightiy over the standard, and it concentrated in Wujiahe, The content of heavy metals during wet season were all higher than those during dry season. Cr, Cu, Zn, and Cd are mainly originated from the nature, Pb and As are separately mainly originated from traffic and agriculture, Mn originated from mining mainly in the downstream, while it has natural source from upper to middle. The health risks of heavy metals in surface water to adults and children in wet season are higher than those in dry season. The main health risk area was the midstream. As was the highest health risk element and children were the most preventive group. Specially, people in towns who drink the water from midstream should pay more attention.

The Seasonal Rainfall Forecast in Nanning City in 2019 with the Method of Trend Comparison Ratio (TCR)

In this paper, the monthly rainfall statistical data of Nanning City, Capital of Guangxi Zhuang Autonomous Region, China, from 2006 to 2018, were collected. On the basis of qualitative analysis of the rainfall seasonal changing law, the non-linear seasonal rainfall forecast model on Nanning City with the method of Trend Comparison Ratio (TCR) was established by the statistical analysis software Office Excel 2013. The model was used to predict the rainfall in spring, summer, autumn and winter in Nanning in 2019. The results were: 286.41 mm, 695.79 mm, 292.20 mm and 118.11 mm, respectively. It was also found that the predicted results were consistent with the seasonal distribution characteristics, annual distribution characteristics and the trend of historical rainfall time series fluctuation, through the qualitative analysis of figures. Compared with the actual measured rainfall data of Nanning City in 2019 in the China Statistical Yearbook (2020), the predicted values are basically consistent with the measured values.

Photovoltaic power interval forecasting method based on kernel density estimation algorithm

Photovoltaic(PV) power forecasting is of great significance to improve the access level of photovoltaic power generation. Deterministic forecasting methods often fail to meet the needs of grid risk analysis and decision-making, and a single model is also difficult to adapt to the changes of PV objects under different meteorological conditions. In order to solve the above problems, this paper describes the seasonal distribution characteristics of PV output fluctuations, and a method of PV power uncertainty forecasting based on seasonal classification is proposed. Compared with the parameter estimation method, the nonparametric kernel density estimation method does not need to make assumptions about the distribution of the prediction error, and can obtain more information about the actual distribution of the error, and has no fixed requirements for the various distribution characteristics of the error, it has strong adaptability.

Responses of intra-annual runoff to forest recovery patterns in subtropical China

Forest recovery plays a critical role in regulating eco-hydrological processes in forested watersheds. However, characteristics of the intra-annual runoff variation associated with different forest recovery patterns remain poorly understood. In this study, three forest change periods were identified, the baseline period (1961–1985), reforestation period (1986 − 2000) and fruit tree planting period (2001–2016). We selected the magnitude of seasonal runoff (wet and dry seasons) and distribution characteristics, i.e., non-uniformity coefficient (Cv), complete accommodation coefficient (Cr), concentration ratio (Cn), concentration period (Cd), absolute variation ratio (ΔR) and relative variation ratio (Cmax). The pair-wise approach evaluated the intra-annual runoff variation characteristics between forest change periods. Results indicate that reforestation decreased wet season runoff and increased dry season runoff. In contrast, fruit tree planting increased wet season runoff and had no significant effect on dry season runoff. For intra-annual runoff distribution characteristics, reforestation significantly reduced the Cv, Cr, Cn and Cmax. Distribution of the intra-annual runoff in the fruit tree planting period was not significantly different from the baseline. We concluded that reforestation reduced the occurance of extreme water conditions in wet and dry seasons and effectively increased the stability of the intra-annual runoff. In contrast, fruit tree planting increased instability and fluctuation of the intra-annual runoff after reforestation. The characteristics of the intra-annual runoff to fruit tree planting was similar to those of the baseline. Therefore, adopting fruit tree planting practices to regulate intra-annual runoff characteristics may not be a practical approach, and impacts of different reforestation practices should be ascertained in our study region. The implications of this study should guide regional land–water management, and this study adds to the understanding of the impacts gained in forest cover on hydrology.

Clinical Characteristics and Electrodiagnostic Features of Guillain-Barré Syndrome Among the Pediatric Population.

Guillain-Barré syndrome is an immune-mediated peripheral neuropathy characterized by different clinical manifestations. We aimed to describe the clinical features, seasonal distribution, subtypes, and electrodiagnostic characteristics of Iranian children with Guillain-Barré syndrome. In this prospective study, a total of 30 children with Guillain-Barré syndrome were evaluated. All demographic features were collected and electrodiagnostic study was assessed. Twelve participants were diagnosed with acute inflammatory demyelinating polyradiculoneuropathy and 18 patients were identified with acute motor axonal neuropathy. The initial findings showed that a significant number of patients (23 cases, P = .003) resided in rural areas. Our results showed a higher incidence of Guillain-Barré syndrome in summer and autumn months. No significant difference was observed between the seasonal distribution of acute inflammatory demyelinating polyradiculoneuropathy and acute motor axonal neuropathy subtypes. Antecedent history of pulmonary infections was recorded in 14 children with Guillain-Barré syndrome. Electrophysiological findings revealed a pattern of prolonged F wave latency with reduced persistency, absence of sensory nerve action potential, reduced compound muscle action potential amplitude, prolonged distal motor latency, reduced nerve conduction velocity, and abnormal temporal dispersion or conduction block in most patients with acute inflammatory demyelinating polyradiculoneuropathy. However, reduced compound muscle action potential amplitude, F wave with normal latency and reduced persistency, normal sensory nerve action potential amplitude, normal distal latency, normal sensory nerve conduction velocity, and conduction block or temporal dispersion were observed in most acute motor axonal neuropathy patients. The data support a correlation between Guillain-Barré syndrome incidence with seasonal variation and living area. Further studies should assess the Guillain-Barré syndrome features in pediatric population.

Distribution Characteristics and Influencing Factors of Uranium Isotopes in Saline Lake Waters in the Northeast of Qaidam Basin

Four saline lakes in the northeast of Qaidam Basin were selected to explore the distribution characteristics and influencing factors of uranium isotopes in lake waters with high evaporation background. The 238U concentration and the activity ratios of 234U/238U ([234U/238U]AR) showed that there was no significant change in the same lake, but there was a certain degree of difference in the distribution between different lakes. We found that aqueous 238U concentration within a certain range increased with an increase in TDS (total dissolved solid) and salinity, as was also the case with pH. As in natural waters, the pH affects the speciation of 238U, but TDS and salinity affect the adsorption process of aqueous 238U. Further, the replenishment of water will also affect the uranium isotope concentration for lakes, but it is not the main influencing factor for saline lakes. Therefore, we suggest that pH is the dominant factor affecting changes in aqueous 238U concentration of the sampled saline lakes. The [234U/238U]AR in these saline lakes are closely related to the input water and the associated water–rock interactions involving sediments, atmosphere dust, and organic material, etc. during the evolution stage, metamorphous degree, and hydrochemistry of the saline lakes. Lake water samples collected in the maximum and minimum discharge water period, were used to evaluate the seasonal distribution characteristics of aqueous 238U, and we found that 238U concentration did not show an evident change with the seasons in these saline lakes. If the 238U concentration and [234U/238U]AR can remain consistent during a period of time, then the sediment ages and/or sedimentation rates could be determined by lake sediment and/or biogenic carbonate in future, thus allowing for the accurate reconstruction of the paleoclimate and paleoenvironment.

Variation Characteristics of Mass Concentration of Inhalable Particles in Qingdao, China

The geographical condition of Qingdao, China is relatively special; the transport of various inland pollutants, the emissions of marine aerosol and local pollutants will have an impact on the changes of atmospheric aerosol concentration. By using the stability classification method, trajectory clustering analysis and the NOAA HYSPLIT model, the seasonal distribution characteristics of atmospheric inhalable particulate matter concentration in Qingdao, China and its relationship with meteorological conditions, mixed layer height, and the seasonal characteristics of Qingdao pollutant transport were analyzed. The results show that the variation trends of PM2.5 and PM10 were about the same, and there are obvious seasonal differences, which are high in winter and spring, and low in summer and autumn. The concentration of inhalable particulate matter has a negative correlation with temperature, wind speed and relative humidity. The concentration of inhalable particulate matter is distinct in different relative humidity ranges. When the wind speed is less than 3 - 4 m/s, there are more inhalable particles, while the mass concentration shows obvious reduction with the wind speed more than 4 m/s. There is a significant negative correlation between the mass concentration of pollutants and the daily maximum mixed layer height. The larger the concentration of pollutants, the smaller the thickness of the daily largest mixed layer. Conversely, the smaller the mass concentration of pollutants, the larger the thickness of the daily largest mixed layer. The pollutant transport in Qingdao has obvious seasonal characteristics. The air mass in spring, autumn and winter is mainly medium-long distance transport from Mongolia and southern Russia, and medium-short distance transport from Inner Mongolia and northeast of China. The source of air masses in summer is mainly transported from the eastern and sea areas.

Seasonal Characteristics Analysis and Uncertainty Measurement for Wind Speed Time Series

Wind speed’s distribution nature such as uncertainty and randomness imposes a challenge in high accuracy forecasting. Based on the energy distribution about the extracted amplitude and associated frequency, the uncertainty measurement is processed through Rényi entropy analysis method with time-frequency nature. Nonparametric statistical method is used to test the randomness of wind speed, more precisely, whether or not the wind speed time series is independent and identically distribution (i.i.d) based on the output probability. Seasonal characteristics of wind speed are analyzed based on self-similarity in periodogram under scales range generated by wavelet transformation to reasonably divide the original dataset and effectively reflect the seasonal distribution characteristics. Experimental evaluation based on the dataset from National Renewable Energy Laboratory (NREL) is given to demonstrate the performance of the proposed approach.

New method of determining height of atmospheric boundary layer and numerical experiment

In this paper, we propose a new method of numerical differentiation to determine the height of the top layer of the atmospheric boundary layer. In this method, a regularization technique is used to convert the problem of calculating the differential of the curve of the corners into the problem of finding the minimum value of the objective function. The two-parameter model function method is used to select the regularization parameters. Finally, the maximum gradient method is used to determine the top height of the boundary layer. Firstly, the effectiveness of the new method is validated through two numerical experiments. The experimental results show that as the noise of the occultation data increases, the fluctuation of the height of the boundary layer top obtained by the difference method and the numerical differentiation method combined with the L curve scheme increases. And the height obtained by the two-parameter model function method is very stable, which shows that the new method can filter the noise well, thereby retaining the main information about the profile. Then, based on the COSMIC angle data in January, April, July and October 2007－2011, the new method is used to analyze the seasonal characteristics of the height of the global oceanic and atmospheric boundary layer, compared with the seasonal distribution obtained by “zbalmax” with the occultation data. The results show that the seasonal distribution characteristics of the two data are very consistent: the height of the boundary layer is higher in the area where the sea surface temperature is higher than that in the surrounding sea area; on the contrary, the height of the boundary layer top is lower. In the sea area where the warm current passes, the height of the boundary layer is higher; in the sea area where the cold current passes, the height of the boundary layer is lower.

PM2.5 Analysis and Prediction Based on Seasonal Time Series Model

The PM2.5 data in Hefei area from 2014 to 2018 were collected through the website of meteorological bureau, and the data were analyzed and modeled with the help of statistical analysis software SPSS and EVIEWS. Firstly, the annual and seasonal distribution characteristics and trend of PM2.5 data in Hefei area during the past five years were analyzed. It was concluded that the distribution of PM2.5 had periodic characteristics, and the air quality in summer was the best and that in winter was the worst. According to the results of statistical analysis, PM2.5 data had seasonal characteristics. On this basis, the Holt-Winters additive model and SARIMA model in seasonal time series model were selected to model and predict. The prediction values of the two models were compared with the real values. The results showed that the prediction accuracy of the Holt-Winters additive model was slightly higher than that of the SARIMA model.

Epidemiological investigation of adenovirus pneumonia in children in Hunan province

Objective To investigate the detection results and epidemiological characteristics of human adenovirus (HAdV) among children with community acquired pneumonia (CAP) in Hunan province. Methods A descriptive retrospective survey was conducted to investigate the clinical epidemiological data of 33 056 children with CAP admitted to the Children′s Medical Center of Hunan People′s Hospital from May 1st, 2014 to April 30th, 2019.The seasonal distribution and demographic characteristics of HAdV infection were analyzed. Results (1) A total of 33 056 children with CAP were included in this study.A total of 3 770 children with HAdV positive were detected, with a total detection rate of 11.40% (3 770/33 056). From May 2014 to April 2019, the detection rates of adenovirus in different years were 13.76%, 8.57%, 7.94%, 9.53%, 12.36% and 24.75% respectively.Adenovirus detection rate reached its peak in 2019.(2) The detection rate of HAdV among male children were higher than that among female children (χ2= 6.374, P=0.012). Among 3 770 children with HAdV infection, 3 036 (80.53%) were from 6 months to 5 years old.The detection rate of adenovirus were different in different age groups.The highest detection rate was 16.65% in 3 to 5 years old group (χ2=526.494, P<0.001). Among children with severe pneumonia, the detection rate of adenovirus was 18.43% (415/2 252). The detection rate of adenovirus was the highest in the age group of 6 months to 1 years, and the difference was statistically significant(χ2=71.485, P<0.001). (3) The detection rate of adenovirus was the lowest in autumn, and the other three seasons were all high- incidence seasons (χ2= 268.744, P<0.001). (4) The hospitalization days of adenovirus pneumonia were longer than those of non-adenovirus pneumonia (Z=-10.419, P<0.001). Conclusion The prevalence of HAdV infection is related to age, season and sex.The susceptibility of adenovirus varies with severity of pneumonia.We should be vigilant against the outbreak of adenovirus infection characterized by years. Key words: Community acquired pneumonia; Adenovirus; Children; Epidemiology

Difference in the thermal response of the occupants living in northern and southern China

Climate is one of the most important factors affecting human thermal comfort. In this study, we explore the influence of regional climate on thermal comfort by considering our data (collected in recent years) with those currently available in the scientific literature. By combining them, we obtained the regional and seasonal database of thermal comfort in China. The regional and seasonal distribution characteristics of indoor/outdoor air temperatures and of human thermal responses have been compared, establishing some relationships. In winter, the thermal environment and human thermal responses between northern and southern China were statistically different; however, they were not statistically different in summer. The seasonal differences in thermal environment and human thermal responses in each region were statistically significant. In neutral thermal environments, the neutral temperature was always close to the indoor mean temperature. In warmer (colder) environments, although the neutral temperature of the subjects was higher (or lower) than the indoor mean temperature, people could always accept their surroundings if provided with available adaptation opportunities. Overall, these findings support the climate adaptation theory and can serve as reference for the design of low-energy buildings.

К ВОПРОСУ О СОВРЕМЕННОМ СОСТОЯНИИ ПОПУЛЯЦИОННОЙ СТРУКТУРЫ СЕРЕБРЯНОГО КАРАСЯ (CARASSIUS AURATUS GIBELIO BLOCH, 1783) И ПРОГНОЗИРОВАНИИ ЕГО ПРОМЫСЛОВОГО ЗАПАСА В РАЗЛИЧНЫХ ГРУППАХ АЗОВСКИХ ЛИМАНОВ

The article presents the results of long-term studies focusing on the population structure, seasonal distribution, migration and other characteristics of the populations of silver carp ( Carassius auratus gibelio Bloch, 1783) in the Azov estuaries. Taking into account the analysis of long-term statistical data of the Azov-Black Sea Territorial Administration of the Federal Fisheries Agency, as well as the results of the proper research on the 161st water body with a total area of more than 62.000 hectares, the commercial catch indices of Prussian carp for 2010-2016 are displayed. Estimation of fish abundance was carried out by direct accounting method based on the results of control fishing in estuaries with various fishing gears, taking into account their catch coefficient. The dynamics of stock indicators, recommended catch level and production of Prussian carp in the Azov estuaries for 2010-2016 has been traced. The main reasons affecting the state of stocks and effective development of the recommended catch of Prussian carp have been analyzed. In order to optimize and increase the efficiency of the fishing organizations of the Krasnodar Territory, Prussian carp stocks and the volumes of its recommended catch in various groups of Azov estuaries were calculated, forecasted indicators for its production for 2018 were given. It has been stated that in connection with a rather high total stock of the population, in the near future Prussian carp will remain the dominant component of the ichthyofauna of the Azov estuaries with the main fishing part concentrated in the Akhtarsk-Griven and the Chernoerkovsk-Sladkov groups of estuaries.

Cluster Analysis of Deep Water Sound Speed Profiles in Indian Ocean

Sound speed profiles in the ocean have a significant impact on the acoustic propagation, thus affecting the sonar detection performance. Sound speed profiles have characteristics of positional and seasonal distribution. In order to guide the sonar detection, use WOA13 dataset, calculate the number of categories of sound speed profiles by hierarchical clustering method, classify sound speed profiles categories and typical sound speed profile structure of various categories in different seasons by fuzzy c-means clustering. It is concluded that there are 7 categories of sound speed profiles in Indian ocean: Antarctic Water category, Antarctic Transition Water category, Sub-Antarctic Transition Water category, Sub-Antarctic Water category, Sub-Tropical Water category, Tropical Divergence Zone category and North Indian Ocean Water category. The distribution area of these categories are generally zonal distribution. Sub-Tropical Water category, Tropical Divergence Zone category and North Indian Ocean Water category have significant seasonal variations. The seasonal variation of other categories are not significant.

Responses of grassland ecosystem productivity to altered precipitation regime: A review.

Under global change scenario, precipitation pattern has significantly changed, mainly in the aspects of annual precipitation amount, precipitation seasonal distribution and precipitation event characteristics (size of individual precipitation event, periods length between two precipitation events, and number of precipitation events in a year), which combined to affect various processes of terrestrial ecosystems, especially productivity. Grassland ecosystem is one of the most sensitive ecosystems to the changes of precipitation regime. Therefore, it is necessary to clarify the responses of productivity to altered precipitation regime in grasslands. In this study, I firstly reviewed the responses of grassland productivity to each characteristic of the altered precipitation regime. Then, I summarized the methods that employed in the study of productivity-precipitation relationship, including long-term observations, manipulative field experiments, and modelling. Finally, I came up with several theoretical and methodological problems that needed to be solved in the future. This work would facilitate the understanding of how grasslands response to the global climate change, with implications for grassland management in the context of climate change.

Seasonal Distribution and Habitat Selection Characteristics of Japanese Wood Pigeon &lt;i&gt;Columba janthina&lt;/i&gt; in Ulleungdo Island

Seasonal Distribution and Habitat Selection Characteristics of Japanese Wood Pigeon &lt;i&gt;Columba janthina&lt;/i&gt; in Ulleungdo Island

Surveillance for Lyme disease in Canada: 2009-2015

ObjectiveThis study aims to describe incidence over time, geographic and seasonal distribution, demographic and clinical characteristics of Lyme disease cases in Canada.IntroductionLyme disease (LD), a multisystem infection that is manifested by progressive stages (1), is emerging in central and eastern provinces of Canada due to northward expansion of the geographic range of Ixodes scapularis, the main vector in these regions (2). In 2004, approximately 40 human cases of LD were reported in Canada. In 2009, LD disease became nationally notifiable, with provincial and territorial health departments reporting clinician-diagnosed cases to the Public Health Agency of Canada (PHAC). This study summarizes seven years (2009-2015) of national surveillance data for LD in Canada.MethodsNational Lyme disease surveillance data is collected through two surveillance systems, the Canadian National Disease Surveillance System (CNDSS) and the Lyme disease enhanced surveillance system (LDES). The CNDSS collects only demographic data (age and sex), and information on episode date and case classification. The LDES system captures additional data, including: possible geographic location of infection (for both locally acquired and travel-related cases); clinical manifestations; and results of laboratory testing. Nine provinces out of ten participate to LDES that means they provide a part of or all the data elements of this surveillance system. The 2009 national Lyme disease case definition (3) that distinguishes confirmed and probable cases (Table 1) is used to classify and report cases diagnosed by clinicians.This study describes the incidence over time, seasonal and geographic distribution, demographic and clinical characteristics of reported LD cases. Logistic regression was used to explore variations among age groups, sex and year of reporting clinical manifestations to better understand potential demographic risk factors for the occurrence of LD. Different models were used with as outcomes absence or presence of: erythema migrans (early Lyme disease), neurologic and cardiac symptoms and multiple erythema, migrans (early disseminated Lyme disease); and arthritis (late disseminated Lyme disease). The most parsimonious multivariate models were sought by backward elimination of nonsignificant variables until all factors in the model were significant (P&lt;0.05).ResultsThe number of reported LD cases increased more than six-fold, from 144 in 2009 to 917 in 2015, mainly due to an increase in infections acquired in Canada. For the provinces participating into the LDES system, the month of illness onset for Lyme disease cases acquired in Canada was available for 2010 cases. Most cases were reported during the summer months of June (20.7%), July (35.4%) and August (17.3%) (Figure 1). An increase in incidence of LD was observed in provinces from Manitoba eastwards (Figure 2). This is consistent with our knowledge of range expansion of the tick vectors in this region. In the western provinces the incidence has remained low and stable. All cases reported by Alberta, Saskatchewan and Newfoundland and Labrador were acquired outside of the province, either elsewhere in Canada or abroad. There was a bimodal distribution for LD by age with peaks at 5–9 and 45–74 years of age (Figure 3). The most common presenting symptoms were a single erythema migrans rash (74.2%) and arthritis (35.7%) (Figure 4). In the multivariate analysis for clinical manifestations, children aged 0–9 years had a greater number of cases reported as early LD (erythema migrans only) than patients aged 10–19 and 30–39 years (P&lt;0.05). For early disseminated manifestations, young adults 20–29 years of age reported more neurologic manifestations, cardiac manifestations or multiple erythema migrans than the reference age group of 0–9 years (P&lt;0.05). For late disseminated manifestations, children under 15 years of age were more frequently reported as having arthritis than other age groups.ConclusionsLyme disease incidence continues to increase in Canada as does the geographic range of ticks that carry the LD bacteria. This increasing of LD incidence might also be due to changing in knowledge, attitudes, and practices of clinicians who diagnose the disease and or of the public health workers who collect and report the data. Ongoing surveillance, preventive strategies as well as early disease recognition and treatment will continue to minimize the impact of LD in Canada.

A seriously sand storm mixed air-polluted area in the margin of Tarim Basin: Temporal-spatial distribution and potential sources

In order to analyze the temporal-spatial distribution characteristics of PM2.5, PM10, SO2, NO2, CO and O3 in five cities and the potential sources of PM10 in southern Xinjiang during 2016, we collected one year officially released data for analysis. The average PM10, PM2.5, SO2, NO2, O3 and CO concentrations were 289 ± 363, 99 ± 106, 17 ± 9, 29 ± 11, 65 ± 25 μg m−3 and 1.3 ± 0.6 mg m−3 in southern Xinjiang in 2016, respectively. The air pollutants presented distinct seasonal and spatial distribution characteristics. During sandstorm process, the particulate matters (PM) concentrations increased abruptly, with the PM10 and PM2.5 maximum concentrations exceeding 1000 and 500 μg m−3 in each city. The backward trajectory results showed that the air masses in Akesu, Kurla, Hotan, Kashi and Atushi were mainly from the Bayingol Mongolian Autonomous Prefecture, Kyrgyzstan, Kizilesu Kirgiz Autonomous Prefecture and Taklimakan Desert (TD). In addition, TD was the main potential contributor to ambient PM10 in five cities during the dust season (DS), with a weighted potential source contribution function (WPSCF) > 0.9. While the trajectories of air masses from TD, Bayingol Mongolian Autonomous Prefecture, Urumqi-Changji Area and local emission were potential sources contributing to PM2.5 in these five cities during DS, with a WPSCF > 0.7. Moreover, the high weighted concentration weighted trajectory (WCWT) values were distributed in the Tarim basin, with PM10 > 700 μg m−3, however, the local emission and long distance transport contributed to the PM2.5 > 160 μg m−3 for five cities. This study comprehensively analyzes the pollution characteristics of air pollutants in five important cities in the southern margin of the Tarim Basin for the first time, and will provide an important reference basis for the prevention and control of air pollution in southern Xinjiang.

A PV power interval forecasting based on seasonal model and nonparametric estimation algorithm

With the continuous increase of grid-connected photovoltaic (PV), high-precision PV power prediction is increasingly important. Extant deterministic forecasting methods do not facilitate fully effective dispatching decisions or power grid risk analysis. Furthermore, the single model also has insufficient generalization ability and unstable forecasting performance in PV power forecasting. This paper proposes an alternative multi-model PV power interval forecasting method which takes into account the seasonal distribution of power fluctuation characteristics. PV output power, absolute power deviation, and relative variation rate are first analyzed for the seasonal distribution characteristics of PV output as they fluctuate over time. Seasonal multi-models for deterministic forecasting of PV power are then built based on an extreme learning machine (ELM). Deterministic forecasting error is fitted by kernel density estimation to complete the PV power interval forecast. The effectiveness of the proposed method is validated by comparison against other methods.

基于典范对应分析的滨海湿地土壤季节性盐渍化特征

PDF HTML阅读 XML下载 导出引用 引用提醒 基于典范对应分析的滨海湿地土壤季节性盐渍化特征 DOI: 10.5846/stxb201806111305 作者: 作者单位: 聊城大学 环境与规划学院,聊城大学 环境与规划学院,聊城大学 环境与规划学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家科技支撑计划项目（2014BAC15B02）；国家自然科学基金项目（40901276，40871239） Characteristics of soil salinization in coastal wetlands based on canonical correspondence analysis Author: Affiliation: School of Environment and Planning,Liaocheng University,Liaocheng,Shandong,252059,School of Environment and Planning,Liaocheng University,Liaocheng,Shandong,252059,School of Environment and Planning,Liaocheng University,Liaocheng,Shandong,252059 Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了更好地开发利用黄河三角洲湿地土壤资源和生态环境建设，运用单因素方差分析（One-way ANOVA）和典范对应分析方法（CCA），对黄河口湿地0-10 cm土壤全盐量（TS）、盐分离子组成、pH、钠吸附比（SAR）、电导率（EC）的季节性变化特征及数量关系进行了分析。结果表明：该区土壤属于盐土类型，春季（5月）、夏季（8月）、秋季（10月）全盐含量均高于17.9 g/kg，且春季、秋季的含盐量高于夏季，造成春、秋季积盐，夏季脱盐。盐分阳离子以Na+为主，阴离子以Cl-为主，除Mg2+在夏季、秋季和Cl-在秋季表现出强烈的变异性外，其余离子在不同季节均表现出中等强度的变异性。春季，Cl-与Na+、Mg2+，SO42-与K+；夏季，Cl-与HCO3-，SO42-与Mg2+、Ca2+，Ca2+与Mg2+；秋季，Cl-与SO42-，SO42-与Mg2+，Ca2+与Mg2+，均有很好的关联性。pH值均介于7.7-8.1之间，各个季节受盐分离子的影响较小，分布较为均匀。SAR介于3.08-5.29之间，春季受控于HCO3-；夏季受控于K+；秋季受各离子的影响均较小，分布较为均匀。EC介于7.16-13.04 mS/cm，春季受各离子的影响均较小，其空间分布较为均匀；夏季受控于SO42-、Ca2+、Mg2+；秋季受控于Na+。TS与Cl-、Na+、Mg2+在季节变化上的差异性一致，且各个季节均受控于Cl-。故通过合理的措施控制或减少Cl-来源是一条减轻黄河口湿地土壤盐渍化的合适途径。 Abstract:To develop and utilize wetland soil resources and ecological environment construction in the Yellow River Delta, a one-way variance analysis (ANOVA) and canonical correspondence analysis (CCA) were applied to analyse the seasonal distribution characteristics and quantitative relationships of total salt content (TS), ion composition, pH value, sodium adsorption ratio (SAR), and electrical conductivity (EC) in the surface layer (0-10 cm) of the soil profile. The results indicated that:(1) the soil of the study area belonged to the type of heavy solonchak,the mean soil salinity was more than 17.9 g/kg in spring (May), summer (August), and autumn (October) and the salt content in May and October was higher than that in August, which caused salification in spring and autumn and desalination in summer. (2)The dominate cation and anion of the soil were Na+ and Cl-, respectively, Mg2+ expressed strong variability in summer and autumn and Cl- in autumn, the other ions showed moderate intensity variation in different seasons. (3) Correlationships between Cl- and Na+, Cl- and Mg2+, and SO42- and K+ were significant in May and Cl- and HCO3-, SO42- and Mg2+, SO42- and Ca2+, Ca2+ and Mg2+ in August, and Cl- and SO42-, SO42- and Mg2+, and Ca2+ and Mg2+ in October. (4) pH values varied between 7.7 and 8.1 and were less influenced by ions and more uniformly distributed in all three seasons. SAR varied between 3.08 and 5.29 and it was strongly influenced in May and K+ in August. It was weakly influenced by any ion and was distributed evenly in October. EC varied between 7.16 and 13.04 mS/cm and it was weakly influenced by ions in the soil and was distributed uniformly in May. However, it was significantly influenced by SO42-, Ca2+, and Mg2+ in August, and Na+ in October. The seasonal variation in TS was coincident with Cl-, Na+, and Mg2+, and Cl- was the major factor controlling spatial distribution of soil total salt throughout all of three seasons. Therefore, controlling or reducing the Cl- source is an optional approach to alleviate soil salinization in the wetlands of the Yellow River Delta. 参考文献 相似文献 引证文献