This paper deals with the protection against earth faults in medium voltage meshed networks with unearthed neutral. A communication-supported protection system is proposed and assessed through ...numerical simulations. The protection system is based on the use of directional relays installed at both ends of each line of the network. Each relay communicates by sending permissive signals following the so-called directional comparison overreaching transfer trip scheme. Each directional relay implements a new transient fault detection algorithm based on the angle between the zero-sequence voltage and current phasors. The phasors are estimated at the dominant frequency of the network transient-response within the first milliseconds after the fault, which range can be evaluated by means of a simplified circuit equivalent representation. The performances of the protection system and the detection algorithm are evaluated for different network configurations. By using a specifically developed co-simulation tool that interfaces EMTP-RV with Matlab, the influence of the communication latency is also analyzed. A Monte Carlo method is applied to analyze the effects of fault resistance, incidence angle and fault location variations. Results of a real-time simulation obtained in the Opal-RT environment further support the applicability of the algorithm.
The state estimation of distribution networks has long been considered a challenging task for the reduced availability of real-time measures with respect to the transmission network case. This issue ...is expected to be improved by the deployment of modern smart meters that can be polled at relatively short time intervals. On the other hand, the management of the information coming from many heterogeneous meters still poses major issues. If low-voltage distribution systems are of interest, a three-phase formulation should be employed for the state estimation due to the typical load imbalance. Moreover, smart meter data may not be perfectly synchronized. This paper presents the implementation of a three-phase state estimation algorithm of a real portion of a low-voltage distribution network with distributed generation equipped with smart meters. The paper compares the typical state estimation algorithm that implements the weighted least squares method with an algorithm based on an iterated Kalman filter. The influence of nonsynchronicity of measurements and of delays in communication and processing is analyzed for both approaches.
•Three building designs with increasing biobased material content were modelled and analysed using LCA.•Dynamic LCA was applied to account for biogenic carbon sequestration, storage and ...emissions.•Increasing biobased content reduces climate impact even if biogenic exchanges are assessed.•Time horizon, timing of forest growth and end-of-life recycling are key assumptions.•Time horizons lower than 100years are not enough to capture properly climate impacts from buildings.
Whenever Life Cycle Assessment (LCA) is used to assess the climate impact of buildings, those with high content of biobased materials result with the lowest impact. Traditional approaches to LCA fail to capture aspects such as biogenic carbon exchanges, their timing and the effects from carbon storage. This paper explores a prospective increase of biobased materials in Swedish buildings, using traditional and dynamic LCA to assess the climate impact effects of this increase. Three alternative designs are analysed; one without biobased material content, a CLT building and an alternative timber design with “increased bio”. Different scenario setups explore the sensitivity to key assumptions such as the building’s service life, end-of-life scenario, setting of forest sequestration before (growth) or after (regrowth) harvesting and time horizon of the dynamic LCA. Results show that increasing the biobased material content in a building reduces its climate impact when biogenic sequestration and emissions are accounted for using traditional or dynamic LCA in all the scenarios explored. The extent of these reductions is significantly sensitive to the end-of-life scenario assumed, the timing of the forest growth or regrowth and the time horizon of the integrated global warming impact in a dynamic LCA. A time horizon longer than one hundred years is necessary if biogenic flows from forest carbon sequestration and the building’s life cycle are accounted for. Further climate impact reductions can be obtained by keeping the biogenic carbon dioxide stored after end-of-life or by extending the building’s service life, but the time horizon and impact allocation among different life cycles must be properly addressed.
Toxin-antitoxin systems are known to be involved in many bacterial functions that can lead to growth arrest and cell death in response to stress. Typically, toxin and antitoxin genes of type I ...systems are located in opposite strands, where the antitoxin is a small antisense RNA (sRNA). In the present work we show that the sRNA IsrA from Salmonella Typhimurium down-regulates the expression of its overlapping gene STM0294.1n. Multiple sequence alignment and comparative structure analysis indicated that STM0294.1n belongs to the SymE toxin superfamily, and the gene was renamed iasE (IsrA-overlapping gene with similarity to SymE). The iasE expression was induced in response to mitomycin C, an SOS-inducing agent; conversely, IsrA overexpression repressed the iasE expression even in the presence of mitomycin C. Accordingly, the inactivation of IsrA with an anti-IsrA RNA expressed in trans abrogated the repressive effect of IsrA on the iasE expression. On the other hand, iasE overexpression, as well as the blockage of the antisense IsrA function, negatively affected bacterial growth, arguing for a toxic effect of the iasE gene product. Besides, a bacterial lysate obtained from the iasE-overexpressing strain exhibited endoribonuclease activity, as determined by a fluorometric assay based on fluorescent reporter RNAs. Together, these results indicate that the IasE/IsrA pair of S. Typhimurium constitutes a functional type I toxin-antitoxin system.
•IasE belongs to the SymE toxin superfamily.•The expression of iasE is induced in response to mitomycin C, an SOS-inducing agent.•The iasE overexpression affects the bacterial growth.•The bacterial lysate from an iasE overexpressing strain exhibits RNase activity.•The iasE/isrA module constitutes a functional type I toxin-antitoxin system.
Base-pairing small RNAs (sRNAs) regulate gene expression commonly by direct interaction with cognate mRNAs. Nevertheless, recent studies have expanded this knowledge with the discovery of the RNA ...'sponges' which are able to interact and repress the functions of classical base-pairing sRNAs. In this work, we present evidence indicating that the sponge RNA SroC from Salmonella enterica serovar Typhimurium base pairs with the MgrR sRNA, thereby antagonizing its regulatory effects on both gene expression and resistance to the antimicrobial peptide polymyxin B (PMB). By a predictive algorithm, we determined putative SroC-MgrR base-pairing regions flanking the interaction area between MgrR and its target mRNA, eptB, encoding a LPS-modifying enzyme. With a two-plasmid system and compensatory mutations, we confirmed that SroC directly interacts and down-regulates the levels of MgrR, thus relieving the MgrR-mediated repression of eptB mRNA. Since it was previously shown that an Escherichia coli strain carrying an mgrR deletion is more resistant to PMB, we assessed the significance of SroC in the susceptibility of S. Typhimurium to PMB. Whereas the sroC deletion increased the sensitivity to PMB, as compared to the wild-type, the resistance phenotypes between the ΔmgrR and ΔsroCΔmgrR strains were comparable, evidencing that mgrR mutation is epistatic to the sroC mutation. Together, these results indicate that both SroC and MgrR sRNAs compose a coherent feed-forward loop controlling the eptB expression and hence the LPS modification in S. Typhimurium.
Abstract Purpose The textile industry faces major challenges in reducing environmental impacts along the whole value chain. The overall aim of this paper was to assess the potential environmental ...benefit of a circular textile value chain, by evaluating a garment partly made from a chemically recycled cellulose carbamate fibre. The cellulose carbamate technology is a novel technology that turns cotton-rich textile waste into a cotton-like regenerated fibre. Methods Life cycle assessment was performed to evaluate the environmental impacts of a garment made from the chemically recycled fibre, considering the whole life cycle. The evaluation also considered that the garment was part of a take-back system, meaning that the garment is collected for recycling after consumer use and thereby helps in closing the loop of the circular textile value chain. The focus of the assessment was on climate impact, water scarcity impact and land use impact. Furthermore, sensitivity analyses were included to test parts of the European Commission’s product environmental footprint method, e.g. the impact of applying the circular footprint formula. Results and discussion The results showed that (1) using a recycled cellulose carbamate fibre over primary conventional cotton showed benefits in all considered environmental impact categories; (2) compared to organic cotton, the benefits were also shown for the land use impact category; (3) the cradle to gate processes were the main hotspots for the garment’s life cycle, meaning that using a recycled feedstock is not the only measure needed to reduce environmental burdens; (4) the use phase, and in particular using the garment to its full life length, is crucial for mitigating the environmental impact per garment use; and (5) methodological choices related to the use of recycled feedstock, and sending materials to recycling at end-of-life, affect the outcome of the study. Conclusions Selecting a chemically recycled cellulose carbamate fibre over primary fibres showed environmental benefits for the evaluated garment, but there are however trade-offs between different environmental impact categories and fibre types. Furthermore, using recycled fibres is one important step in reducing the environmental concerns of garments, but it is important to also make improvements along the whole textile value chain.
Small noncoding RNAs (sRNAs) are important regulators of gene expression and physiology in bacteria. RyhB is an iron-responsive sRNA well characterized in Escherichia coli and conserved in other ...Enterobacteriaceae. In this study, we identified and characterized two RyhB homologs (named RyhB-1 and RyhB-2) in the fish pathogen Yersinia ruckeri. We found that, as in other Enterobacteriaceae, both RyhB-1 and RyhB-2 are induced under iron starvation, repressed by the Fur regulator, and depend on Hfq for stability. Despite these similarities in expression, the mutant strains of Y. ruckeri lacking RyhB-1 (ΔryhB-1) or RyhB-2 (ΔryhB-2) exhibited differential phenotypes. In comparison with the wild type, the ΔryhB-1 strain showed a hypermotile phenotype, reduced biofilm formation, increased replication rate, faster growth, and increased ATP levels in bacterial cultures. By contrast, in salmon cell cultures, the ΔryhB-1 strain exhibited an increased survival. On the other hand, the ΔryhB-2 strain was non-motile and showed augmented biofilm formation as compared to the wild type. The expression of a subset of RyhB conserved targets, selected from different bacterial species, was analyzed by quantitative RT-PCR in wild type, ΔryhB-1, ΔryhB-2, and ΔryhB-1 ΔryhB-2 strains cultured in iron-depleted media. RyhB-1 negatively affected the expression of most analyzed genes (sodB, acnA, sdhC, bfr, fliF, among others), whose functions are related to metabolism and motility, involving iron-containing proteins. Among the genes analyzed, only sdhC and bfr appeared as targets for RyhB-2. Taken together, these results indicate that Y. ruckeri RyhB homologs participate in the modulation of the bacterial physiology with non-redundant roles.
•The influence of load dynamics in the islanding transition of a microgrid is assessed.•A sensitivity analysis of exponential and rotating load parameters is presented.•Increase values of system ...inertia ease the islanding transition of a microgrid.•Including rotating loads is important to assess the transient stability of microgrids.
Microgrids (MGs) are characterized by faster dynamics than conventional grid-connected distributions systems. This is in part due to the lack of inertia of inverter-interfaced distributed energy resources such as photovoltaic and energy storage systems. In this context, load dynamics considerably affects the transient stability performance of MGs, especially if disconnected from the main grid. The aim of the paper is to analyze the influence of the load modeling and the load composition in the transient stability assessment of a medium voltage MG during islanding transition. The MG we analyze consists of a photovoltaic power plant, two battery energy storage systems, a synchronous generator and different classes and types of load, which we consider representative for the problem of interest. The system is implemented in the EMTP-RV simulation environment. The importance of appropriate load modeling for the adequate analysis of the transient response of an islanding microgrid is also addressed and discussed.
The fashion industry faces major challenges in reducing its environmental impacts along the textile value chain, from fibre production, via various processing steps, use phase and to the end-of-life ...stage. A major challenge is how to shift from the current linear industry to a circular one, where textiles are both sustainably produced, and after the full life length, recycled into new fibres with high value applications. The aim of this study was to evaluate the environmental impacts of post-consumer textile fibre-to-fibre recycling by cellulose carbamate technology, in terms of climate impact, water scarcity impact, cumulative energy demand and land use impact. By performing life cycle assessment, it was shown that the chemically recycled cellulose carbamate fibre has a climate impact of about 2.2 kg CO2-eq per kg fibre, water scarcity impact of 1.6 m3 H2O-eq per kg fibre, cumulative energy demand of 90 MJ-eq per kg fibre and land use impact of about 92 Pt per kg fibre (when applying mass allocation of co-products). Hotspots identified during the fibre production technology were electricity use and production of sodium hydroxide. In a sensitivity analysis, it was shown that the choice of electricity has a major influence on the results, and by using a renewable electricity mix over an average Finnish electricity mix, the impact could be decreased for all impact categories, except when using bioenergy, which would increase the land use impact. Compared to primary fibres like viscose and conventional cotton, these impacts are in the lower to middle range, showing potential to lower environmental impacts when moving towards an increased amounts of recycled post-consumer textile fibre with high value applications, that can replace primary fibres.
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•An LCA study for a novel man-made cellulose carbamate fibre.•System boundary from discarded post-consumer textiles to regenerated textile fibre.•Cellulose carbamate technology recycles textile waste into high value applications.•Potential to lower environmental impacts compared to primary textile fibres.•Hotspots were electricity use and production of sodium hydroxide.
This paper examines the main non-technical factors that influence social and market acceptance of solar photovoltaic panels and heat pumps in buildings. The paper discusses results from a literature ...review and a survey of European stakeholders. Statistical analysis results of survey data identify the most common barriers to adoption of renewables as: limited information about the technology, financial concerns, and sociodemographic factors. Survey results indicate variability in market and social acceptance of renewables between stakeholders and countries. The investment cost of the technologies is identified as a barrier to adoption for all countries. Legal and organizational issues are identified as barriers in Spain. Economic and legal barriers are identified as barriers in Latvia and Belgium. The respondents from Germany only identify investment cost as a barrier. Economic aspects are identified as the main barriers among public building owners and the general public. Businesspeople identified the largest number of barriers, including economic aspects, lack of information, trust, business models, and legal issues, while private building owners identified the least number of barriers, with concerns only related to economic aspects. Results of this study provide valuable information for policymaking focused on increasing the adoption of renewables in the building sector. Additionally, this study identifies the need to increase environmental awareness among citizens and increase the availability of information about technologies to stakeholders. Citizens should be informed about the recoupment of the investment costs of the technologies to offset the perception of high investment costs, long payback time, and lack of proper business models.
•A literature review of social and market acceptance of renewable energy technologies.•Review based on a conceptualization of acceptance.•A stakeholder survey based on key aspects of acceptance identified in the review.•Statistical data analysis to identify trends and correlations.•Results can validate previous findings or create new knowledge for decision makers.
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