1,387 research outputs found
Optimal Scheduling of Distributed Energy Resources Considering Volt-VAr Controller of PV Smart Inverters
This paper proposes an operational scheduling model of distributed energy
resources (DERs) and PV smart inverters with Volt-VAr controller using an
accurate AC optimal power flow (ACOPF) in an unbalanced distribution network. A
mathematical mixed-integer model of local Volt-VAr droop controller of the
distributed mixed-phase PV smart inverters is proposed based on the IEEE
1547-2018 standard and is incorporated in the unbalanced ACOPF, which enables
effective utilization of the Volt-VAr controllers to not only alleviate voltage
issues locally but also at the feeder level. The proposed model is tested on
two actual snapshots of a distribution feeder in Arizona. Also, the proposed
operational scheduling method considering the Volt-VAr droop controller of PV
smart inverters is compared with a recent work in scheduling of the PV smart
inverters. The results illustrate that the PV smart inverters dispatches
obtained by the proposed model can be practically implemented by local
controller of inverters.Comment: In proceedings of the 11th Bulk Power Systems Dynamics and Control
Symposium (IREP 2022), July 25-30, 2022, Banff, Canad
Quantum teleportation with nonclassical correlated states in noninertial frames
Quantum teleportation is studied in noninertial frame, for fermionic case,
when Alice and Bob share a general nonclassical correlated state. In
noninertial frames two fidelities of teleportation are given. It is found that
the average fidelity of teleportation from a separable and nonclassical
correlated state is increasing with the amount of nonclassical correlation of
the state. However, for any particular nonclassical correlated state, the
fidelity of teleportation decreases by increasing the acceleration.Comment: 10 pages, 3 figures, expanded version to appear in Quantum Inf.
Proces
The impact of human capital in determining cooperative strategies—the case of cooperatives in the Souss-Massa region, Morocco
The question of the importance of the social and solidarity economy is important, not only in Morocco, but everywhere in the world. It is within this framework that we have tried to determine the impact of human capital on social and solidarity economy organizations, and more precisely on the strategies adopted by cooperatives, indeed, human capital plays an essential role, by improving innovation, by creating the preconditions for the growth of organizations, and above all by tackling good strategic planning. In this perspective, the objective of this research and to emphasize the link between the level of education and the strategy adopted by the cooperative.In this work, we have tried to statistically analyze the data collected from cooperatives in order to answer our problem, using several tools, such as: factor analysis and discriminant analysis.The question of the importance of the social and solidarity economy is important, not only in Morocco, but everywhere in the world. It is within this framework that we have tried to determine the impact of human capital on social and solidarity economy organizations, and more precisely on the strategies adopted by cooperatives, indeed, human capital plays an essential role, by improving innovation, by creating the preconditions for the growth of organizations, and above all by tackling good strategic planning. In this perspective, the objective of this research and to emphasize the link between the level of education and the strategy adopted by the cooperative.In this work, we have tried to statistically analyze the data collected from cooperatives in order to answer our problem, using several tools, such as: factor analysis and discriminant analysis
Review on the strategies to improve the mechanical strength of highly porous bone bioceramic scaffolds
Bone healing is an impressive ability of the human body, but critical-sized bone defects require external intervention. Bioceramic scaffolds with excellent biocompatibility and bioactivity have been developed to treat non-healing bone defects because of their unique features for bone repair. Meanwhile, the mechanical properties of the material continue to be disadvantageous. This review focuses on (i) essential factors in affecting and improving bioceramic-based scaffolds' mechanical properties, including porosity, pore size, methods, and material composition, and (ii) summarizing previous studies and highlighting strategies to fabricate scaffolds with improved mechanical properties such as using nano-particles, using a combination of bioceramics and polymers, and modifying scaffold surfaces. Further research is necessary to improve bioceramic scaffolds for bone repair applications.Peer reviewe
DCE-MRI perfusion and permeability parameters as predictors of tumor response to CCRT in patients with locally advanced NSCLC
In this prospective study, 36 patients with stage III non-small cell lung cancers (NSCLC), who underwent dynamic contrast-enhanced MRI (DCE-MRI) before concurrent chemo-radiotherapy (CCRT) were enrolled. Pharmacokinetic analysis was carried out after non-rigid motion registration. The perfusion parameters including Blood Flow (BF), Blood Volume (BV), Mean Transit Time (MTT) and permeability parameters including endothelial transfer constant (Ktrans), reflux rate (Kep), fractional extravascular extracellular space volume (Ve), fractional plasma volume (Vp) were calculated, and their relationship with tumor regression was evaluated. The value of these parameters on predicting responders were calculated by receiver operating characteristic (ROC) curve. Multivariate logistic regression analysis was conducted to find the independent variables. Tumor regression rate is negatively correlated with V e and its standard variation V e-SD and positively correlated with K trans and Kep. Significant differences between responders and non-responders existed in Ktrans, Kep, Ve, Ve-SD, MTT, BV-SD and MTT-SD (P < 0.05). ROC indicated that Ve < 0.24 gave the largest area under curve of 0.865 to predict responders. Multivariate logistic regression analysis also showed Ve was a significant predictor. Baseline perfusion and permeability parameters calculated from DCE-MRI were seen to be a viable tool for predicting the early treatment response after CCRT of NSCLC. © 2016 The Author(s)
An epidemiological study of pleuropulmonary paragonimiasis among pupils in the peri-urban zone of Kumba town, Meme Division, Cameroon
BACKGROUND: Paragonimiasis have previously been reported in two zones of the Southwest Province of Cameroon including the Kupe mountain and Mundani foci. The aim of this study was to investigate the presence and epidemiology of paragonimiasis in the peri-urban zone of Kumba, Meme Division, located about 50 km away from the Kupe mountain focus. METHODS: Pupils of several government primary schools in 5 villages around Kumba underwent both parasitologic and clinical investigations in search of signs and symptoms of paragonimiasis. Mycobacterium tuberculosis was also searched for in the differential diagnosis.Freshwater crabs from neighbouring streams in the five villages were dissected in search of paragonimus metacercariae. RESULTS: Out of a total of 1482 pupils examined in all five villages, 309 individuals (147 males and 162 females) were recruited for this study based on the presence of one or more signs or symptoms of paragonimiasis. Eggs of Paragonimus africanus were found in stools and/or sputum of pupils from all five villages, giving an overall paragonimus prevalence of 2.56%. There was no significant difference in the disease prevalence between the villages (X(2 )= 8.36, P = 0.08). The prevalence of Paragonimus africanus eggs amongst pupils with symptoms of paragonimiasis was 12.3% (38 of 309). Males were infected more than females (17.0% versus 8.0%), but the difference was not significant (X(2 )= 5.76, P = 0.16). All the 38 paragonimus egg positive subjects presented with cough, 23 (60.53%) complained of chest pain while 16 (42.11%) had haemoptysis. Stool examinations also detected some intestinal parasites including Ascaris lumbricoides (29.45%), Trichuris trichiura (6.47%), Necator americanus (2.27%), Strongyloides stercoralis (1.62%), Enterobius vermicularis (0.65%), and Entamoeba histolytica (4.53%). No case of M. tuberculosis was noted. Out of a total of 85 dissected crabs (Sudanonautes africanus), 6.02 % were infected with paragonimus metacercariae. CONCLUSION: In addition to the two previously described paragonimiasis foci of Kupe mountain and Mundani, the identification of autochthonous cases of paragonimiasis in the peri-urban zone of Kumba town, makes the South West Province the most endemic zone of paragonimiasis in Cameroon at present
International entrepreneurship in SMEs: a study of influencing factors in the textile industry
The final publication is available at Springer via http://dx.doi.org/10.1007/s11365-012-0242-3International entrepreneurship is an incipient research area with a rapidly increasing body of knowledge and contributions. An important part of this literature has focused on the analysis of the contributing factors to IE development. From these studies, this work attempts to analyse and validate through an integrative model the effect on this construct in SME of some of the main factors proposed by the literature such as Skills and Competences, Attitude and Proactiveness, Creativity and Innovation, Networking, Employees and Activity. To proceed with this aim, we conducted an empirical research focused on 174 textile SME in Spain. The results obtained confirm a positive relationship between the studied factors and the IE development. 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Academic performance of undergraduate dental students with learning disabilities
© 2017 British Dental Association. All rights reserved.Aims To compare the academic performance of undergraduate dental students with known learning disabilities (LDs) to their peers.Methods This study analysed the results of students in applied dental knowledge (ADK) progress tests across four cohorts of dental students. A mixed model analysis of variance (ANOVA) was conducted to compare the performance of students with known disability to their peers. ADK test sitting was treated as a repeated measures variable, and the outcome variable of interest was percentage score on the ADK.Results Students' performance data on five ADK test sittings (ADK15, ADK16, ADK17, ADK18, and ADK19) by disability showed a significant main effect of test but no significant effect of disability or any interaction between disability and test.Conclusions This is the first study that explores the academic performance of dental students with a diagnosis of disability. The findings give reassurance to all stakeholders that, within the study population, students with LDs are not disadvantaged in knowledge-based assessments, demonstrating compliance with the legal obligations. Further research is required to explore how generalisable these findings are, as well as assess academic, clinical, and behavioural attributes of students with learning disabilities
Performance of polyethyleneimine–silica adsorbent for post-combustion CO2 capture in a bubbling fluidized bed
The high performance of polyethyleneimine (PEI)-based solid adsorbent for CO2 capture has been well recognized in thermogravimetric analysis (TGA) and small-scale fixed bed reactors through the measurements of their equilibrium capacities but has not been really demonstrated on larger scales towards practical utilization. In the present study, a laboratory-scale bubbling fluidized bed reactor loaded with a few kg adsorbent is used to evaluate the adsorption performance of PEI–silica adsorbent under different working conditions including with/without the presence of moisture, different gas–solid contact times, initial bed temperatures, and CO2 partial pressures. The adsorption capacities have shown a clear degradation tendency under dry condition. However, they can be stabilized at a high level of 10.6–11.1% w/w over 60 cycles if moisture (ca. 8.8 vol%) is present in the gas flow during adsorption and desorption. Breakthrough capacities can be stabilized at the level of 7.6–8.2% w/w with the gas–solid contact time of 13 s. The adsorption capacities for the simulated flue gases containing 5% CO2 are only slightly lower than those for the simulated flue gases containing 15% CO2, indicating that the PEI–silica adsorbent is suitable for CO2 capture from flue gases of both coal-fired and natural gas-fired combined cycle power plants. The exothermal heat of adsorption is estimated by the energy balance in the fluidized bed reactor and found to be close (within 10%) to the measured value by TG-DSC. The regeneration heat for the as prepared PEI–silica adsorbent is found to be 2360 kJ/kgCO2 assuming 75% recovery of sensible heat which is well below the values of 3900–4500 kJ/kgCO2 for a typical MEA scrubbing process with 90% recovery of sensible heat
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