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2021 ◽  
Vol 10 (4) ◽  
pp. 911-922
Author(s):  
Marouane Lagouir ◽  
Abdelmajid Badri ◽  
Yassine Sayouti

This paper deals with the multi-objective optimization dispatch (MOOD) problem in a DC microgrid. The aim is to formulate the MOOD to simultaneously minimize the operating cost, pollutant emission level of (NOx, SO2 and CO2) and the power loss of conversion devices.  Taking into account the equality and inequality constraints of the system. Two approaches have been adopted to solve the MOOD issue. The scalarization approach is first introduced, which combines the weighted sum method with price penalty factor to aggregate objective functions and obtain Pareto optimal solutions. Whilst, the Pareto approach is based on the implementation of evolutionary multi-objective optimization solution. Single and multi-objective versions of multi-verse optimizer algorithm are, respectively, employed in both approaches to handle the MOOD. For each time step, a fuzzy set theory is selected to find the best compromise solution in the Pareto optimal set. The simulation results reveal that the Pareto approach achieves the best performances with a considerable decrease of 28.96 $/day in the daily operating cost, a slight reduction in the power loss of conversion devices from 419.79 kWh to 419.29 kWh, and in less computational time. While, it is noticing a small increment in the pollutant emission level from 11.54 kg/day to 12.21 kg/day, for the daily microgrid operation. This deviation can be fully covered when comparing the cost related to the treatment of these pollutants, which is only 5.55 $/day, to the significant reduction in the operating cost obtained using the Pareto approach.


2021 ◽  
Vol 895 ◽  
pp. 130-138
Author(s):  
Maher Faroq Al-Lebban ◽  
Abeer Ibraheem Khazaly ◽  
Rana Shabbar ◽  
Qusay A. Jabal ◽  
Layth Abdul Rasool Al Asadi

This investigation aims to improve some of the mechanical properties of concrete such as compressive strength, flexural strength, and modulus of elasticity, by using different percentages of polypropylene fibers, and also studying the durability of concrete for freeze-thaw cycles. the study shows a small increment in compressive strength due to adding fibers which were 28.3% compared with increment in flexural strength which was perfect (about 191%), modulus of elasticity also increased by adding fibers. The durability of concrete against freezing-thaw cycles for all mixes was studied. Fiber-reinforced concrete shows more durability against freezing-thawing cycles and less reduction in strength compared with reference mixes without fibers,21.5% reduction in strength for optimum polypropylene fiber concrete while the reduction in strength for normal concrete was found 54.2% in this study.


Healthcare ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 856
Author(s):  
Markel Rico-González ◽  
José Pino-Ortega ◽  
Filipe Manuel Clemente ◽  
Naia Bustamante-Hernández

Immunoglobulin A (IgA), which is the main effector against upper respiratory tract viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been related to training load management. The aim of this systematic review was to establish the relationship between training load and salivary IgA based on current evidence in order to avoid immunosuppression after exercise and players´ vulnerability to virus contagion. A systematic review of relevant articles was carried out using two electronic databases (PubMed and Web of Science) until 19 May 2021. From a total of 127 studies initially found, 23 were included in the qualitative synthesis. These studies were clustered depending on stress level. The salivary IgA was analysed considering soccer-specific treadmill exercise and repeated sprint drills (n = 5), matches (n = 7), and during certain periods during the season or pre-season (n = 11). Repeated sprint ability tests and treadmill exercises are suitable exercises for the first steps on return to play periods yet still maintain social distance. A rest or moderate training sessions (technical/tactical) are suggested after official matches to ensure 16–18 h to recover IgA levels, while periods with multiple matches per week with limited recovery time should be avoided. Weekly training load should assume a small increment (<10%) to ensure IgA immune responses, especially, during the post coronavirus disease 2019 (COVID-19) season.


2021 ◽  
Vol 14 (6) ◽  
pp. 3813-3841
Author(s):  
Phuc T. M. Ha ◽  
Ryoki Matsuda ◽  
Yugo Kanaya ◽  
Fumikazu Taketani ◽  
Kengo Sudo

Abstract. This study uses a chemistry–climate model CHASER (MIROC) to explore the roles of heterogeneous reactions (HRs) in global tropospheric chemistry. Three distinct HRs of N2O5, HO2, and RO2 are considered for surfaces of aerosols and cloud particles. The model simulation is verified with EANET and EMEP stationary observations; R/V Mirai ship-based data; ATom1 aircraft measurements; satellite observations by OMI, ISCCP, and CALIPSO-GOCCP; and reanalysis data JRA55. The heterogeneous chemistry facilitates improvement of model performance with respect to observations for NO2, OH, CO, and O3, especially in the lower troposphere. The calculated effects of heterogeneous reactions cause marked changes in global abundances of O3 (−2.96 %), NOx (−2.19 %), CO (+3.28 %), and global mean CH4 lifetime (+5.91 %). These global effects were contributed mostly by N2O5 uptake onto aerosols in the middle troposphere. At the surface, HO2 uptake gives the largest contributions, with a particularly significant effect in the North Pacific region (−24 % O3, +68 % NOx, +8 % CO, and −70 % OH), mainly attributable to its uptake onto clouds. The RO2 reaction has a small contribution, but its global mean negative effects on O3 and CO are not negligible. In general, the uptakes onto ice crystals and cloud droplets that occur mainly by HO2 and RO2 radicals cause smaller global effects than the aerosol-uptake effects by N2O5 radicals (+1.34 % CH4 lifetime, +1.71 % NOx, −0.56 % O3, +0.63 % CO abundances). Nonlinear responses of tropospheric O3, NOx, and OH to the N2O5 and HO2 uptakes are found in the same modeling framework of this study (R>0.93). Although all HRs showed negative tendencies for OH and O3 levels, the effects of HR(HO2) on the tropospheric abundance of O3 showed a small increment with an increasing loss rate. However, this positive tendency turns to reduction at higher rates (>5 times). Our results demonstrate that the HRs affect not only polluted areas but also remote areas such as the mid-latitude sea boundary layer and upper troposphere. Furthermore, HR(HO2) can bring challenges to pollution reduction efforts because it causes opposite effects between NOx (increase) and surface O3 (decrease).


2021 ◽  
Author(s):  
Rosalia Leonardi ◽  
Vincenzo Ronsivalle ◽  
Manuel O. Lagravere ◽  
Ersilia Barbato ◽  
Gaetano Isola ◽  
...  

ABSTRACT Objectives To assess changes in spheno-occipital synchondrosis after rapid maxillary expansion (RME) performed with conventional tooth-borne (TB) and bone-borne (BB) appliances. Materials and Methods This study included 40 subjects with transverse maxillary deficiency who received TB RME or BB RME. Cone-beam computed tomography images (CBCT) were taken before treatment (T0), and after a 6-month retention period (T1). Three-dimensional surface models of the spheno-occipital synchondrosis and basilar part of the occipital bone were generated. The CBCTs taken at T0 and T1 were registered at the anterior cranial fossa via voxel-based superimposition. Quantitative evaluation of Basion displacement was performed with linear measurements and Euclidean distances. The volume of the synchndrosis was also calculated for each time point as well as the Nasion-Sella-Basion angle (N-S-Ba°). All data were statistically analyzed to perform inter-timing and intergroup comparisons. Results In both groups, there was a small increment of the volume of the synchondrosis and of N-S-Ba° (P &lt; .05). Basion showed a posterosuperior pattern of displacement. However, no significant differences (P &gt; .05) were found between the two groups. Conclusions Although TB and BB RME seemed to have some effects on the spheno-occipital synchondrosis, differences were very small and clinically negligible.


2021 ◽  
Vol 19 (1) ◽  
pp. 1-9
Author(s):  
Pravash Budhathoki ◽  
Dhan Bahadur Shrestha ◽  
Sitaram Khadka ◽  
Era Rawal

Background: The global spread of COVID-19 and the lack of definite treatment have caused an alarming crisis in the world. We aimed to evaluate the outcome and potential harmful cardiac effects of hydroxychloroquine and azithromycin compared to hydroxychloroquine alone for COVID-19 treatment.Methods: PubMed, Medline, Google Scholar, Cochrane Library, clinicaltrials.gov, and World Health Organization clinical trial registry were searched using appropriate keywords and identified six studies using PRISMA guidelines. The quantitative synthesis was performed using fixed or random effects for the pooling of studies based on heterogeneities.Results: The risk of mortality (RR=1.16; CI: 0.92-1.46) and adverse cardiac events (OR=1.06; CI: 0.82-1.37) demonstrated a small increment though of no significance. There were no increased odds of mechanical ventilation (OR=0.84; CI: 0.33-2.15) and significant QTc prolongation (OR=0.84, CI: 0.59-1.21). Neither the critical QTc threshold (OR=1.92, CI: 0.81-4.56) nor absolute ?QTc ?60ms (OR=1.95, CI:0.55-6.96) increased to the level of statistical significance among hydroxychloroquine and azithromycin arm compared to hydroxychloroquine alone, but the slightly increased odds need to be considered in clinical practice. Conclusions: The combination of hydroxychloroquine and azithromycin leads to small increased odds of mortality and cardiac events compared to hydroxychloroquine alone. The use of hydroxychloroquine and azithromycin led to increased odds of QT prolongation, although not statistically significant.Keywords: COVID-19; COVID-19 drug treatment; hydroxychloroquine; macrolides; severe acute respiratory syndrome coronavirus 2 


Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 542
Author(s):  
Qing Gu ◽  
Xiaxu Huang ◽  
Jiangtao Xi ◽  
Zhenfeng Gao

The influence of a magnetic field of 1.2–1.3 T on the variation of the fatigue behaviors and the mechanical properties of a 35CrMo steel after fatigue tests are investigated in this paper, in order to provide a basic guidance on the application in the similar environment of electrical machinery or vehicles. The microstructures of samples tested with and without magnetic fields are observed and analyzed by XRD, SEM, and TEM techniques. The fatigue life cycles are slightly increased by about 10–15% under magnetic field of 1.2–1.3 T according to the experimental results. A small increment of yield strength under fatigue life cycles of 10,000, 50,000, and 100,000 times is caused by the magnetic field, although the enhancement is only of 5–8 MPa. The dislocation density of the specimen is increased and the uniformity of dislocations is improved by magnetic fields applied during fatigue tests under the same load and cycles. The formation of micro-defects or micro-cracks will be postponed by the improvement in homogeneity of the material, leading to the increase of mechanical properties. The strengthening mechanisms such as deformation hardening and dislocation hardening effects are enhanced by the dislocation entangled structures and the higher density caused by magnetic field.


Author(s):  
Zaitul Akmal AZ ◽  
Salmah N ◽  
ND Ismail ◽  
Muhammad Akmal MN ◽  
Khairatul Nainey K

Introduction: In Malaysia, the rate of adolescents involved in sexual activities has increased and starts at an earlier age. Data from NHMS 2017 showed that 7.3% among surveyed 13 to 17 years-old adolescents have already had sex. The rate of teenage pregnancies is also increasing at 3.7-3.9% between the years 2009 until 2011. Therefore, an effective SRH Programme should be conducted in schools to equip them with adequate knowledge regarding this subject.Methods: A cross-sectional questionnaire survey was conducted among 145 randomly selected secondary school students aged 13 to 15 years old, attending the SRH Programme in a secondary school in Cheras, Selangor, Malaysia. The objective of this programme is to deliver knowledge and promote awareness among adolescents regarding SRH. The programme consists of intervention using adolescent-friendly module and games. A pre- and post-test were given to the participants to evaluate the effectiveness of the programme using the validated SRH questionnaire (Malay version). The questionnaire consists of fourteen and six items for knowledge and attitude, respectively.Results: The result showed an increase in the mean knowledge score (±SD) after the SRH Programme at the school from 7.25 ± 2.44 for pre-test to 9.70 ± 3.17 for post-test. The mean difference in pre- and post-test was 2.45 (95% CI: 2.02, 2.87) and was statistically significant (p<0.001). In terms of attitudes, the majority of the students felt that they have enough knowledge to make a gooddecision regarding sexual reproductive health issues after the SRH programme. However, there was only a small increment with regards to their attitudes on assertiveness.Conclusion: This study demonstrated an increase in the level of knowledge among adolescents in Cheras after the SRH programme using the adolescent-friendly module and games. However, there is no significant change in attitude among adolescents regarding SRH.Future SRH programmes need to be done regularly to instil positive attitudes among adolescents in dealing withsexual reproductive dilemmas.International Journal of Human and Health Sciences Supplementary Issue: 2021 Page: S20


2021 ◽  
pp. 24-32
Author(s):  
Р.Р. Исхужин ◽  
В.Н. Борисов ◽  
В.Г. Атавин ◽  
А.А. Узких ◽  
К.К. Хафизова

The work considers the methodology of weld ultrasonic inspection of thin-wall (0.6 mm) titanium alloy shells. The paper also presents a review of publications on Lamb wave excitation and propagation, and on applications of ultrasonic inspection of thin-wall weldments. The problem of adhesion detection was successfully solved (weld zones with incomplete fusion conduct ultrasonic waves well, but do not provide mechanical strength). Angular groove is proposed as an indication of incomplete fusion in the weld. We analyzed different propagation modes of Lamb wave in the material and selected optimum inspection parameters. Wavelet analysis and precise digital filters with small increment provided great efficiency. Inspection results of corrupted weld and defect-free regions were analyzed. The results of ultrasonic scanning were compared to metallographic study data.


2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Hui Cheng ◽  
Karl Gunnar Aarsæther ◽  
Lin Li ◽  
Muk Chen Ong

Abstract Compared with the multipoint mooring fish cage, the single-point mooring (SPM) fish cage can spread out the fish wastes and uneaten feeds in a larger area, and it can also prevent the local environment from being overwhelmed. Thus, it has attracted much attention recently. In this research, different deformation-suppression methods are applied to the SPM system with a typical Norwegian fish cage aiming to increase the cultivation volume under the action of current and/or wave loads. A well-validated software, fhsim, is used to conduct the full-scale numerical study. The effects of the three deformation-suppression methods, i.e., (i) adding the lower bridles, (ii) adding the frontal rigid frame and (iii) adding the trawl doors, are analyzed under pure current and combined wave–current conditions. The results indicate that all the three deformation-suppression methods can improve the cultivation volume at least by 32% compared to the original SPM fish cage when the current velocity is larger than 0.5 m/s. In addition, moving the conjunction point close to the bottom ring can bring a positive effect on the cultivation volume maintaining with an only small increment in the tension force. This study can provide practical advice and useful guides for the SPM fish cage design.


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