A market-based transmission planning for HVDC grid—case study of the North Sea

There is significant interest in building HVDC transmission to carry out transnational power exchange and deliver cheaper electricity from renewable energy sources which are located far from the load centers. This paper presents a market-based approach to solve a long-term TEP for meshed VSC-HVDC grids that connect regional markets. This is in general a nonlinear, non-convex large-scale optimization problem with high computational burden, partly due to the many combinations of wind and load that become possible. We developed a two-step iterative algorithm that first selects a subset of operating hours using a clustering technique, and then seeks to maximize the social welfare of all regions and minimize the investment capital of transmission infrastructure subject to technical and economic constraints. The outcome of the optimization is an optimal grid design with a topology and transmission capacities that results in congestion revenue paying off investment by the end the project's economic lifetime. Approximations are made to allow an analytical solution to the problem and demonstrate that an HVDC pricing mechanism can be consistent with an AC counterpart. The model is used to investigate development of the offshore grid in the North Sea. Simulation results are interpreted in economic terms and show the effectiveness of our proposed two-step approach

Analysis of North Sea offshore wind power variability

This paper evaluates, for a 2030 scenario, the impact on onshore power systems in terms of the variability of the power generated by 81 GW of offshore wind farms installed in the North Sea. Meso-scale reanalysis data are used as input for computing the hourly power production for offshore wind farms, and this total production is analyzed to identify the largest aggregated hourly power variations. Based on publicly available information, a simplified representation of the coastal power grid is built for the countries bordering the North Sea. Wind farms less than 60 km from shore are connected radially to the mainland, while the rest are connected to a hypothetical offshore HVDC (High-Voltage Direct Current) power grid, designed such that wind curtailment does not exceed 1% of production. Loads and conventional power plants by technology and associated cost curves are computed for the various national power systems, based on 2030 projections. Using the MATLAB-based MATPOWER toolbox, the hourly optimal power flow for this regional hybrid AC/DC grid is computed for high, low and medium years from the meso-scale database. The largest net load variations are evaluated per market area and related to the extra load-following reserves that may be needed from conventional generators.Parts of this work were funded by Agentschap.NL, the Netherlands, now RVO.nl (Rijksdienst voor Ondernemend Nederland [25], under the project North Sea Transnational Grid (NSTG). The NSTG project is a cooperation between Delft University of Technology and the Energy Research Center of the Netherlands

Concealment, communication and stigma: The perspectives of HIV-positive immigrant Black African men and their partners living in the United Kingdom

This study explored the perspectives of Black men, originally from East Africa, living in the United Kingdom and their families on what it means to live with diagnosed HIV. This article reports on concealment of HIV-positive status as a strategy adopted by the affected participants to manage the flow of information about their HIV-positive status. Analysis of the data, collected using in-depth interviews involving 23 participants, found widespread selective concealment of HIV-positive status. However, a few respondents had ‘come out’ publicly about their condition. HIV prevention initiatives should recognise concealment as a vital strategy in managing communication about one’s HIV-positive status

Research on four drilling and sampling methods for groundwater up to five metres below groundwater level in sandy areas

NB Klik hier voor de zip file met Bijlage 11: Analyseresultaten en veldgegevens ronde 1 t/m 3 De zogeheten Multi-Channel Well (MCW) geplaatst met de SonicSampDrill blijkt de beste methode te zijn om het grondwater bij landbouwbedrijven tot vijf meter onder de grondwaterspiegel te analyseren. Dat komt vooral doordat deze methode in staat is om tot die diepte met een machinale trilboring meerdere monsternemingsfilters te plaatsen. Daardoor zijn minder boorgaten nodig. Momenteel wordt bij landbouwbedrijven de grondwaterkwaliteit gemeten in de bovenste meter van het grondwater. Met die metingen, uitgevoerd binnen het Landelijk Meetnet Effecten Mestbeleid (LMM) worden effecten van het mestbeleid op de grondwaterkwaliteit onderzocht; die effecten weerspiegelen zich in de bovenste meter. Daarnaast worden deze metingen gebruikt om de grondwaterkwaliteit te toetsen aan de nitraatnorm. Momenteel wordt onderzocht of de toetsdiepte voor nitraat verlaagd kan worden naar vijf meter. Ten eerste omdat de Europese regelgeving daar ruimte voor lijkt te bieden. Ten tweede omdat nitraatconcentraties dieper in de bodem kunnen afnemen. Hierdoor wordt nu mogelijk te streng getoetst. Met de LMM-methode kan echter niet zo diep geboord worden. Mocht de toetsdiepte worden verlaagd, dan is dus een andere monsternemingsmethode vereist. Het RIVM heeft vier methoden onderzocht. Het onderzoek is uitgevoerd op zestien boorlocaties bij vier melkveehouderijbedrijven verspreid over de vier grote zandgebieden in Nederland (Noord, Oost, Centraal en Zuid). De onderzochte methoden kenmerken zich onder andere door handmatig of machinaal boren en door de installatie van tijdelijke of permanente filters. De methoden zijn beoordeeld op hun praktische inzetbaarheid en op de kwaliteit van de monsterneming. Zo blijkt de handmatige Van der Staay-methode, die tijdelijke filters plaatst, slechts op vijftig procent van de locaties op de gewenste diepte te kunnen komen. Met de machinale Uitschuifbare Punt-methode, die ook tijdelijke filters plaatst, is het boren en het verzamelen van watermonsters in de praktijk niet goed te combineren. Bij de MCW en de Direct Well-methode (DW) worden na machinale boring permanente filters geplaatst. In tegenstelling tot de MCW heeft de DW daarbij voor ieder filter een apart boorgat nodig.The so-called Multi-Channel Well (MCW), installed using the SonicSampDrill, has proven to be the best method for analysing groundwater on farms up to five metres below groundwater level. This is because this method - using just one sonic drilling allows placement of multiple sampling filters up to five metres below this level, so fewer boreholes are needed. At the moment, groundwater quality on farms in the Netherlands is measured in the uppermost one metre of the groundwater. These measurements, carried out in the framework of the Netherlands National Monitoring Programme for Effectiveness of the Minerals Policy (LLM in Dutch) are used to determine effects of the fertiliser policy on the groundwater quality; effects are reflected in the topmost metre. Besides this, measurements are also used to test the groundwater quality against the nitrate standard. At the moment it is being investigated if the test depth can be lowered to five metres. First of all, because this seems to be in line with the European regulations. And secondly, because concentrations of nitrate deeper in the soil can decrease. This involves the possibility of too stringent testing at the moment. However, the LMM method does not allow such deep drilling, so a lower test depth will require another drilling and sampling method. RIVM has investigated four methods at four dairy farms. These dairy farms are spread across the four large sandy areas in the Netherlands (north, east, centre and south). Every farm contains four drilling sites, totalling 16. The methods investigated are characterised, for example, by hand or machine drilling and by the installation of temporary or permanent filters. Methods are assessed on practical application and the quality of the sampling. With the manual Van der Staay method, in which temporary filters are installed, the desired depth is achieved at only 50 per cent of the sites. With the use of the mechanised Extendable Point Method, in which temporary filters are placed too, drilling and water sampling forms a poor combination in practice. The MCW and the Direct Well (DW) methods allow placement of permanent filters after machine drilling. Contrary to the MCW method, the DW method requires a separate borehole for each filter.VROMLN

Evidence of biomass smoke exposure as a causative factor for the development of COPD

© 2017 by the authors. Chronic obstructive pulmonary disease (COPD) is a progressive disease of the lungs characterised by chronic inflammation, obstruction of airways, and destruction of the parenchyma (emphysema). These changes gradually impair lung function and prevent normal breathing. In 2002, COPD was the fifth leading cause of death, and is estimated by theWorld Health Organisation (WHO) to become the third by 2020. Cigarette smokers are thought to be the most at risk of developing COPD. However, recent studies have shown that people with life-long exposure to biomass smoke are also at high risk of developing COPD. Most common in developing countries, biomass fuels such as wood and coal are used for cooking and heating indoors on a daily basis. Women and children have the highest amounts of exposures and are therefore more likely to develop the disease. Despite epidemiological studies providing evidence of the causative relationship between biomass smoke and COPD, there are still limited mechanistic studies on how biomass smoke causes, and contributes to the progression of COPD. This review will focus upon why biomass fuels are used, and their relationship to COPD. It will also suggest methodological approaches to model biomass exposure in vitro and in vivo

Acute upper airway failure and mediastinal emphysema following a wire-guided percutaneous cricothyrotomy in a patient with severe maxillofacial trauma

Contains fulltext : 69538.pdf (publisher's version ) (Open Access)BACKGROUND: In the presence of severe maxillofacial trauma, management of the airway is important because this condition poses a significant threat to airway patency. That securing the airway is not always straightforward is described and illustrated in this paper. CASE: We present the case of a 23-year-old patient who sustained severe maxillofacial injury for which airway control was necessary. A wire-guided percutaneous dilation cricothyrotomy was performed, which was most probably the cause of an acute loss of airway patency. The literature regarding the role of percutaneous techniques in an elective and emergency setting is reviewed

Analysis of the Brinkman-Forchheimer equations with slip boundary conditions

In this work, we study the Brinkman-Forchheimer equations driven under slip boundary conditions of friction type. We prove the existence and uniqueness of weak solutions by means of regularization combined with the Faedo-Galerkin approach. Next we discuss the continuity of the solution with respect to Brinkman's and Forchheimer's coefficients. Finally, we show that the weak solution of the corresponding stationary problem is stable

Extracellular Matrix Oxidised by the Granulocyte Oxidants Hypochlorous and Hypobromous Acid Reduces Lung Fibroblast Adhesion and Proliferation In Vitro.

Chronic airway inflammation and oxidative stress play crucial roles in the pathogenesis of chronic inflammatory lung diseases, with airway inflammation being a key driving mechanism of oxidative stress in the lungs. Inflammatory responses in the lungs activate neutrophils and/or eosinophils, leading to the generation of hypohalous acids (HOX). These HOX oxidants can damage the extracellular matrix (ECM) structure and may influence cell-ECM interactions. The ECM of the lung provides structural, mechanical, and biochemical support for cells and determines the airway structure. One of the critical cells in chronic respiratory disease is the fibroblast. Thus, we hypothesised that primary human lung fibroblasts (PHLF) exposed to an oxidised cell-derived ECM will result in functional changes to the PHLF. Here, we show that PHLF adhesion, proliferation, and inflammatory cytokine secretion is affected by exposure to HOX-induced oxidisation of the cell-derived ECM. Furthermore, we investigated the impact on fibroblast function from the presence of haloamines in the ECM. Haloamines are chemical by-products of HOX and, like the HOX, haloamines can also modify the ECM. In conclusion, this study revealed that oxidising the cell-derived ECM might contribute to functional changes in PHLF, a key mechanism behind the pathogenesis of inflammatory lung diseases

Modulation of neural regulators of energy homeostasis, and of inflammation, in the pups of mice exposed to e-cigarettes

© 2018 Background: Maternal smoking can lead to perturbations in central metabolic regulators such as neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) signalling components in offspring. With the growing interest in e-cigarettes as a tobacco replacement, this short report assessed central metabolic regulation in offspring of mouse dams exposed to e-cigarettes. We examined the impact of continuous use of e-cigarettes, and e-cigarette replacement of tobacco cigarettes during pregnancy. Supplementation of an antioxidant L-carnitine was also co-used with tobacco cigarette in the mother to determine whether the impact of maternal tobacco smoking was oxidative stress driven. Methods: Balb/c mice were exposed to either nicotine-containing (E-cig18) or nicotine-free (E-cig0) e-cigarette aerosols or tobacco smoke (SE) prior to mating and until their pups were weaned. After mating, two SE sub-groups were changed to E-cig18 exposure (Replacement), or supplementation L-carnitine while SE was continued. Male offspring were studied at weaning age. Results: The offspring of E-cig0 dams were the heaviest with the most body fat. Replacing SE with E-cig18 during pregnancy resulted in offspring with significantly less body fat. E-cig0 offspring had significantly increased mRNA expression of brain NPY and iNOS. Maternal SE upregulated mRNA expression of NPY, NPY Y1 receptor, POMC downstream components, and iNOS expression, which were normalised in Replacement offspring, but only partially normalised with maternal L-carnitine supplementation during gestation and lactation. Conclusions: Maternal exposure to either tobacco and nicotine-free e-cigarettes lead to disturbances in the level of central homeostatic control markers in offspring, suggesting that maternal exposure to e-cigarettes is not without risks