Day-ahead allocation of operation reserve in composite power systems with large-scale centralized wind farms

This paper focuses on the day-ahead allocation of operation reserve considering wind power prediction error and network transmission constraints in a composite power system. A two-level model that solves the allocation problem is presented. The upper model allocates operation reserve among subsystems from the economic point of view. In the upper model, transmission constraints of tielines are formulated to represent limited reserve support from the neighboring system due to wind power fluctuation. The lower model evaluates the system on the reserve schedule from the reliability point of view. In the lower model, the reliability evaluation of composite power system is performed by using Monte Carlo simulation in a multi-area system. Wind power prediction errors and tieline constraints are incorporated. The reserve requirements in the upper model are iteratively adjusted by the resulting reliability indices from the lower model. Thus, the reserve allocation is gradually optimized until the system achieves the balance between reliability and economy. A modified two-area reliability test system (RTS) is analyzed to demonstrate the validity of the method.This work was supported by National Natural Science Foundation of China (No. 51277141) and National High Technology Research and Development Program of China (863 Program) (No. 2011AA05A103)

The role of climate, marine influence and sedimentation rates in late-Holocene estuarine evolution (SW Portugal)

Estuaries are sensitive to changes in global to regional sea level, to climate-driven variation in rainfall and to fluvial discharge. In this study, we use source and environmentally sensitive proxies together with radiocarbon dating to examine a 7-m-thick sedimentary record from the Sado estuary accumulated throughout the last 3.6 kyr. The lithofacies, geochemistry and diatom assemblages in the sediments accumulated between 3570 and 3240 cal. BP indicate a mixture between terrestrial and marine sources. The relative contribution of each source varied through time as sedimentation progressed in a low intertidal to high subtidal and low-energy accreting tidal flat. The sedimentation proceeded under a general pattern of drier and higher aridity conditions, punctuated by century-long changes of the rainfall regime that mirror an increase in storminess that affected SW Portugal and Europe. The sediment sequence contains evidence of two periods characterized by downstream displacement of the estuarine/freshwater transitional boundary, dated to 3570-3400 cal. BP and 3300-3240 cal. BP. These are intercalated by one episode where marine influence shifted upstream. All sedimentation episodes developed under high terrestrial sediment delivery to this transitional region, leading to exceptionally high sedimentation rates, independently of the relative expression of terrestrial/marine influences in sediment facies. Our data show that these disturbances are mainly climate-driven and related to variations in rainfall and only secondarily with regional sea-level oscillations. From 3240 cal. BP onwards, an abrupt change in sediment facies is noted, in which the silting estuarine bottom reaches mean sea level and continued accreting until present under prevailing freshwater conditions, the tidal flat changing to an alluvial plain. The environmental modification is accompanied by a pronounced change in sedimentation rate that decreased by two orders of magnitude, reflecting the loss of accommodation space rather than the influence of climate or regional sea-level drivers.FCT by Spanish Ministry of Science and Innovation [SFRH/BD/110270/2015, HAR2014-51830-P, HAR2011-29907-C03-00]FCTPortuguese Foundation for Science and Technology [PTDC/HISARQ/121592/2010]Instituto Dom Luiz-IDL [UID/GEO/50019/2013]info:eu-repo/semantics/publishedVersio

Knowledge and behaviors regarding salt intake in Mozambique

Background/objectives: Health education and regulatory measures may contribute to lower population salt intake. Therefore, we aimed to describe knowledge and behaviors related to salt intake in Mozambique. Subjects/methods: A cross-sectional evaluation of a representative sample of the population aged 15–64 years (n = 3116) was conducted in 2014/2015, following the Stepwise Approach to Chronic Disease Risk Factor Surveillance, including a 12-question module for evaluation of dietary salt. Results: Three dimensions were identified in the questionnaire, named “self-reported salt intake”, “knowledge of health effects of salt intake”, and “behaviors for control of salt intake”. A total of 7.4% of the participants perceived that they consumed too much/far too much salt and 25.9% reported adding salt/salty seasoning often/always to prepared foods. The proportion considering that it was not important to decrease the salt contents of their diet was 8%, and 16.9% were not aware that high salt intake could be deleterious for health. Prevalences of lack of behaviors for reducing salt intake ranged from 74.9% for not limiting consumption of processed foods, to 95% for not buying low salt alternatives. There were few differences according to socio-demographic variables, but awareness of hypertension was, in general, associated with better knowledge and less frequent behaviors likely to contribute to a high salt intake. Conclusions: Most Mozambicans were aware that high salt intake can cause health problems, but the self-reported salt intake and behaviors for its control show an ample margin for improvement. This study provides evidence to guide population level salt-reducing policies

Phylogenetic relationships within Chamaecrista sect. Xerocalyx (Leguminosae, Caesalpinioideae) inferred from the cpDNA trnE-trnT intergenic spacer and nrDNA ITS sequences

Chamaecrista belongs to subtribe Cassiinae (Caesalpinioideae), and it comprises over 330 species, divided into six sections. The section Xerocalyx has been subjected to a profound taxonomic shuffling over the years. Therefore, we conducted a phylogenetic analysis using a cpDNA trnE-trnT intergenic spacer and nrDNA ITS/5.8S sequences from Cassiinae taxa, in an attempt to elucidate the relationships within this section from Chamaecrista. The tree topology was congruent between the two data sets studied in which the monophyly of the genus Chamaecrista was strongly supported. Our analyses reinforce that new sectional boundaries must be defined in the Chamaecrista genus, especially the inclusion of sections Caliciopsis and Xerocalyx in sect. Chamaecrista, considered here paraphyletic. The section Xerocalyx was strongly supported as monophyletic; however, the current data did not show C. ramosa (microphyllous) and C. desvauxii (macrophyllous) and their respective varieties in distinct clades, suggesting that speciation events are still ongoing in these specimens

Inter-population variation on the accumulation and translocation of potentially harmful chemical elements in Cistus ladanifer L. from Brancanes, Caveira, Chan double dagger a, Lousal, Neves Corvo and So Domingos mines in the Portuguese Iberian Pyrite Belt

This study aimed to compare the variation on the accumulation and translocation of potentially harmful chemical elements and nutrients (As, Ca, Cu, Fe, K, Mg, Mn, Ni, Pb and Zn) in Cistus ladanifer L. belonging to populations growing in different mine areas from the Portuguese Iberian Pyrite Belt (Brancanes, Caveira, Chan double dagger a, Lousal, Neves Corvo, So Domingos). These mines are abandoned (except Neves Corvo that is still operating) and have different contamination levels. Composite samples of soils (n = 31), developed on different mine wastes and/or host rock, and C. ladanifer plants (roots and shoots) were collected in the mine areas. Soils were characterized for pH, NPK and organic C, by classical methodologies. Soils (total fraction-four acid digestion, and available fraction-extracted with aqueous solution of diluted organic acids, simulating rizosphere conditions) and plants (ashing followed by acid digestion) elemental concentrations were determined by ICP. Soil-plant transfer and translocation coefficients were calculated. Principal components analysis in both ways, the classical method and a second approach with adaptations used mostly in multivariate statistical processes control data, were done in order to compare the plants populations. Soils had large heterogeneity in their characteristics. Caveira, Lousal, Neves Corvo and So Domingos soils showed the highest total concentrations of As, Cu, Pb and Zn. Independently of the mine, available fractions of elements were low. Intra- and inter-population variations in accumulation and translocation of elements were evaluated. Plants were not accumulators of the majority of the analysed elements. Nutrients were mainly translocated from roots to shoots, while trace elements were stored in roots (except in Neves Corvo for As and Pb, and So Domingos for As). Elements concentrations in plant populations from Lousal, Chan double dagger a and So Domingos did not present much variation. Brancanes soils and plants presented strong differences compared to other areas. Cistus ladanifer plants are able to survive in mining areas with polymetallic contamination at different elements concentrations in total and available fraction. This species presented variations inter- and intra-populations in accumulation and translocation of chemical elements; however, all studied populations, except Brancanes, can belong to the same population cluster