A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids

This paper presents a novel cooperative control technique concerning fully-distributed AC/DC microgrids. Distributed generation based on inverters has two types, i.e., Current Source Inverter (CSI), also referred to as PQ inverter, and Voltage Source Inverter (VSI). Both inverter forms have a two-layer coordination mechanism. This paper proposes a design method for the digital Proportional-Resonant (PR) controller that regulates the current inside an inverter. The inverters will improve the voltage quality of the microgrid while maintaining the average voltage of buses at the same desired level. There is comprehensive detail on the computations specific to resonant and proportional gains and digital resonance path coefficients. The paper includes a digital PR controller design and its analysis in the frequency domain. The analysis is based on the w-domain. The main contribution of this paper is the proposed method, which not only focuses on the transient response but also improves the steady-state response which smoothens the voltage; furthermore, all inverters are effectively involved to increase the capacity of the microgrid for better power management. The suggested cooperative control technique is used on an IEEE 14-bus system having fully distributed communication. The convincing outcomes indicate that the suggested control technique is an effectual means of regulating the microgrid’s voltage to obtain an evener and steady voltage profile. The microgrid comprises distributed resources and is used as the primary element to analyse power flow and quality indicators associated with a smart grid. Lastly, numerical simulation observations are utilised for substantiating the recommended algorithm

A New Robust Control Strategy for Parallel Operated Inverters in Green Energy Applications

This research work puts forward a hybrid AC/DC microgrid with renewable energy sources pertaining to consumer’s residential area for meeting the demand. Currently, the power generation and consumption have experienced key transformations. One such tendency would be integration of microgrids into the distribution network that is characterized by high penetration of renewable energy resources as well as operations in parallel. Traditional droop control can be employed in order to get an accurate steady state averaged active power sharing amongst parallel inverters pertaining to hybrid AC/DC microgrid. It is presumed that there would be similar transient average power responses, and there would be no circulating current flowing between the units for identical inverters possessing the same droop gain. However, the instantaneous power could be affected by different line impedances considerably and thus resulting in variation in circulating power that flows amongst inverters, especially during unexpected disturbances like load changes. This power, if absorbed by the inverter, could result in sudden DC-link voltage rise and trip the inverter, which in turn causes performance degradation of the entire hybrid microgrid. When the hybrid generators act as unidirectional power source, the issue worsens further. In this research work, we have put forward a new distributed coordinated control pertaining to hybrid microgrid, which can be applied for both grid connected and islanded modes that include variable loads and hybrid energy resources. Also, in order to choose the most effective controller scheme, a participation factor analysis has been designed for binding the DC-link voltage as well as reducing the circulating power. Moreover, to both photovoltaic stations and wind turbines, maximum power point tracking (MPPT) techniques have been used in order to extract the maximum power from hybrid power system when there is discrepancy in environmental circumstances. Lastly, the feasibility and effectiveness pertaining to the introduced strategy for hybrid microgrid in various modes are confirmed via simulation results

Prioritizing areas for ecological restoration: A participatory approach based on cost-effectiveness

1. Landscape-scale prioritization models are powerful decision-making tools in ecological restoration. Yet, they often fail to integrate multi-stakeholder perspectives and socio-ecological criteria. 2. We designed a new methodology to identify high-priority areas for landscape-scale restoration. This participatory cost-effectiveness analysis model is based on execution and maintenance costs and the potential increase in the supply of multiple ecosystem services. 3. We tested the model in a 181,000 ha heavily anthropized semi-arid landscape in southeastern Spain. Restoring the whole area would cost 221 million EUR and enhance the supply of ecosystem services by 39%. The cost-effectiveness of restoring pine forest and abandoned and irrigated crops were higher than restoring other Landscape Units. Restoring the least degraded sites was more cost-effective than the most degraded areas or randomly selecting sites, even when potential recovery was incomplete. 4. Synthesis and applications. The cost-effectiveness of restoration actions depends on the type of ecosystem and degradation state. Visualizing the outcomes of alternative restoration scenarios needs participatory prioritization maps based on financial costs and the potential supply of ecosystem services. We propose a participatory prioritization protocol that is flexible and adaptable and can help government agencies, environmental managers, investors, consultancies and NGOs' plan restoration actions at the landscape scale and optimize the effectiveness of restoration programs.This research has been financially supported by the Ministry of Science, Education and Universities, the Ministry of Economy, Industry, and Competitiveness of the Spanish Government, and European Regional Development Funds (FEDER; projects TERECOVA CGL2014-52714-C2-1-R and COSTERA, RTI2018-095954-B-I00), and Conselleria d'Innovació, Universitats, Ciència i Societat Digital, Generalitat Valenciana (Project R2D, CIPROM/2021/001)

Maternal Mortality Ratio and Universal Access to Reproductive Health Care in the State of Qatar between 1990 and 2012: A PEARL Study Analysis

Study Aim: The Millennium Development Goal (MDG)- 5 mandates a three quarters reduction in Maternal Mortality Ratio (MMR) and provision of universal access to reproductive health by 2015. Our study aims to analyze Qatar’s performance in achieving MDG 5 between 1990 and 2012.Study Design: A National Prospective cohort-studyData Source: Qatar Perinatal Registry (Q-Peri-Reg) for 2011 and 2012 dataMethods: National data on total deliveries, total births (live and stillbirths) and maternal mortality (during pregnancy to day 42 post-delivery) was collected from all public and private maternity units in Qatar (1st January 2011- December, 31st 2012) and compared with historical maternal mortality data (1990-2010) ascertained from the database of maternity and neonatal units of Women’s Hospital, annual reports of Hamad Medical Corporation and international reports. For inter country comparison, country data was extracted from World Health Statistics 2011(WHO).Results: The country wide live births were 20583 during 2011 and 22,225 during 2012 with two maternal deaths duringeach year giving an MMR of 9.85/100,000 and 8.99/100,000 live births respectively which was more than three quarters decline from an MMR of 49/100,000 in 1990. During 2011, 74.22% deliveries were normal vaginal (n 15076) and 25.78% (n 5238) by Caesarean section. 99.45 % of deliveries were attended by a trained birth attendant in a maternity facility while 0.55 % (n = 114) took place out of hospital. 100% of mothers had made at least one antenatal visit and 100% of live births were examined by a pediatrician and entered in national birth register. Qatar’s 2011 and 2012 MMR is significantly lower than the current global MMR of 260/100,000 and Eastern Mediterranean Region MMR of 320/100,000.Conclusion: Qatar has achieved its target MDG 5 well before 2015. Qatar’s 2011 and 2012 MMR is comparable to most high income countries. Qatar’s reproductive health system, with its universal access for all, provides a unique model to study the correlates and associations of maternal survival which can form the basis of global health systems improvement strategies

Graphes de cordes : une caractérisation et ses applications

Université : Université scientifique et médicale de GrenobleIntroduction. Graphes de cordes. Généralités. Diagrammes orientés. Orientations géométriques. Pseudo-tournois de cordes orientées. PL-graphes. Graphes de cordes et matroïdes binaires. Bibliographi

Evaluation of Urban Planning Projects Criteria Using Fuzzy AHP Technique

In this research, Fuzzy Analytic Hierarchy Process technique is applied (Fuzzy AHP) which is one of multi-criteria decision making techniques to evaluate the criteria for urban planning projects, the project of developing master plan of Al-Muqdadiyah city to 2035 has been chosen as a case study. The researcher prepared a list of criteria in addition to the authorized departments criteria and previous researches in order to choose optimized master plan according to these criteria. This research aims at employing the foundations of (Fuzzy AHP) technique in evaluating urban planning criteria precisely and flexible. The results of the data analysis to the individuals of the sample who are specialists, in this aspect. The land use criteria are more important than the rest of the criteria in these projects, where it received the relative importance with percentile (42.1 %)

Erratum: Alhasnawi et al. A New Robust Control Strategy for Parallel Operated Inverters in Green Energy Applications. <i>Energies</i> 2020, <i>13</i>, 3480

The authors wish to make the following corrections to this paper [...

Physicochemical and Antibacterial Properties of Conventional and Two Premixed Root Canal Filling Materials in Primary Teeth

International audienceIn this study, some physicochemical and antibacterial properties of three root canal filling materials for primary teeth, Calplus "CP" (Prevest DenPro, Lewes, DE, USA), Bio-C Pulpecto "Bio-CP" (Angelus, Basil, Londrina, Paraná, Brazil), and Zinc Oxide and Eugenol "ZOE" (Prevest DenPro, Lewes, DE, USA) were compared. For each material, the pH, solubility, contact angle, and crystalline microstructure under SEM were evaluated. Their antibacterial activity against Enterococcus faecalis was determined through direct tests. The Kruskal-Wallis test was used to analyze the results using a one-way analysis of variance on ranks. All the materials had an alkaline pH at 3, 24, and 72 h, with CalPlus having the highest (p < 0.05). Bio-CP was more soluble during the evaluation period (24 h) than ZOE and CalPlus (p < 0.05). Bio-CP and ZOE demonstrated the creation of crystallite structures on their surfaces after immersion in PBS at 37 • C, whereas CalPlus showed none. The lowest contact angle was observed for Bio-CP (53 ± 1.5 •); contact angles of (86 ± 4 •) and (96 ± 1 •), respectively, were observed after 10 s of the deposition of the water drop for CalPlus and ZOE. In conclusion, according to this study, there is still a need to develop new filling materials for primary teeth. ZOE, CalPlus and Bio-CP demonstrated different physicochemical and antibacterial properties, but none of the materials had optimal properties and could be considered the most suitable filling material for primary teeth pulpectomy. Bioceramics in their current state are not an alternative. The physicochemical and antibacterial properties still need improvement to fit the intricate anatomy of primary teeth

Effectiveness of the REvision System and Sonic Irrigation in the Removal of Root Canal Filling Material from Oval Canals: An In Vitro Study

This study aimed to evaluate the effectiveness of the Endostar REvision system (Poldent, Warsaw, Poland) in the removal of filling materials from oval root canals using sonic irrigation as an additional cleaning method. Thirty human-extracted mandibular premolars with oval canals were prepared using the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland) up to instrument F1 (20/.07), and then filled by the continuous wave vertical compaction technique using pulp canal sealer EWT (Sybron Dental Specialties, Orange, CA, USA). The teeth were randomly divided into two groups (n = 15) according to the instrumentation system and the additional cleaning method, as follows: REvision (30/.08, 25/.06) with EQ-S sonic activation (Meta Biomed, Chungcheongbuk-do, Korea), REvision (30/.08, 25/.06) without additional activation. All specimens were sectioned longitudinally at 3 and 7 mm from the apex, and analyzed using digital microscopy (KEYENCE, Osaka, Japan) to measure the total area of the residual obturation materials, followed by SEM analysis. The data on the percentage of remaining filling material were analyzed by Kruskal–Wallis one-way Analysis of Variance on ranks. None of the retreatment protocols completely removed the filling material from the root canals (p > 0.05); the retreatment technique using sonic activation showed statistically less residual filling materials than the retreatment technique using irrigants without activation at the coronal third (p 0.05). The REvision system showed promising results in the removal of filling materials from oval canal