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Comprehensive Assessment of Large-Scale Photovoltaic Integration in an Isolated Mining Microgrid: Dynamic Stability, Protection Coordination, and Power Quality Analysis  [PDF]
Medhy Kayembe Kazadi, Narcisse Meni Babakidi
Circuits and Systems (CS) , 2026, DOI: 10.4236/cs.2026.175005
Abstract: The decarbonization of isolated mining operations has accelerated the adoption of large-scale photovoltaic (PV) generation as a sustainable alternative to diesel-based electricity production. However, high PV penetration in isolated microgrids introduces significant technical challenges, including reduced system inertia, voltage and frequency instability, protection coordination, fault-current variation, and power quality degradation. This study presents a comprehensive technical assessment of integrating a 15 MW photovoltaic power plant into the isolated electrical network of the Société Minière de Dinguiraye (SMD) gold mine in Guinea using ETAP Version 22.5. A high-fidelity digital model of the mining power system was developed, incorporating diesel generators, medium-voltage distribution networks, transformers, industrial loads, photovoltaic generation, advanced inverter controls, protection systems, and an optional Battery Energy Storage System (BESS). Five representative operating scenarios were investigated through load-flow, transient stability, short-circuit, protection coordination, harmonic, and renewable intermittency analyses to evaluate the operational performance of the proposed hybrid diesel-PV microgrid. Simulation results demonstrate that the integration of the 15 MW PV plant substantially reduces diesel generation while maintaining acceptable voltage regulation, frequency stability, rotor-angle stability, protection selectivity, and harmonic distortion within the limits specified by IEEE 519. The implementation of advanced inverter control functions and BESS-based fast frequency response further enhances voltage support, improves frequency recovery following disturbances, mitigates renewable intermittency, and increases the overall resilience of the isolated microgrid. The study confirms that large-scale photovoltaic integration can be achieved without compromising system reliability, operational security, or power quality when supported by appropriate control strategies and protection coordination. The proposed ETAP-based assessment framework provides a practical and reproducible engineering methodology for the planning, design, and implementation of renewable-powered isolated mining microgrids, contributing to the decarbonization and sustainable electrification of remote mining operations.
A Conserved Phase-Field Model with Dirichlet Boundary Condition and Regular Potentials  [PDF]
Narcisse Batangouna
Applied Mathematics (AM) , 2026, DOI: 10.4236/am.2026.173009
Abstract: Phase field models are a fundamental tool in describing phase transition phenomena. In this context, our study focuses on a conserved phase field model, subject to Dirichlet boundary conditions and incorporating regular potentials. The main objective of this article is to rigorously establish the existence and uniqueness of solutions for the model under consideration. The Dirichlet boundary conditions impose constraints on the behavior of the phase field at the boundary of the domain.
Analysis of Bitcoin Pooled Mining Reward Systems
Meni Rosenfeld
Computer Science , 2011,
Abstract: In this paper we describe the various scoring systems used to calculate rewards of participants in Bitcoin pooled mining, explain the problems each were designed to solve and analyze their respective advantages and disadvantages.
Analysis of Hashrate-Based Double Spending
Meni Rosenfeld
Computer Science , 2014,
Abstract: Bitcoin is the world's first decentralized digital currency. Its main technical innovation is the use of a blockchain and hash-based proof of work to synchronize transactions and prevent double-spending the currency. While the qualitative nature of this system is well understood, there is widespread confusion about its quantitative aspects and how they relate to attack vectors and their countermeasures. In this paper we take a look at the stochastic processes underlying typical attacks and their resulting probabilities of success.
Aggression on the Road as a Function of Stress, Coping Strategies and Driver Style  [PDF]
Lipaz Shamoa-Nir, Meni Koslowsky
Psychology (PSYCH) , 2010, DOI: 10.4236/psych.2010.11006
Abstract: According to Lazarus and Folkman’s [1] transactional cognitive model, people differ in their sensitivity and vulnerabil- ity to stressful events. Using questionnaire and observational techniques, the model was tested as a possible explanation for aggressive driving behavior. Responses from 226 drivers who were also observed driving their cars provided evidence for a link between stress and aggressive driving as well as between problem-solving strategy as a coping device in stressful situations and hostile behaviors. In addition, analysis showed that, in general, the more years of driving experience a driver has, the more likely he/she is to respond with instrumental rather than hostile aggression. Besides support for the theoretical model, some of the practical applications as they related to highway safety and the prevention of traffic accidents were presented.
Emotional Intelligence as a Mediator between Teachers’ Emotional Mistreatment and Long-Term Emotional Impact on Students  [PDF]
Bat Katzman, Niva Dolev, Meni Koslowsky
Psychology (PSYCH) , 2021, DOI: 10.4236/psych.2021.122020
Abstract: Teacher emotional mistreatment, which includes both verbal and nonverbal abusive behaviors, is a widespread and harmful experience for school students. However, its long-term emotional impacts remain relatively unexplored. This study explored the mediating role of emotional intelligence (EI) on the association between teacher’s emotional mistreatment towards school children and the long-term emotional impact on the students. A total of 377 Israeli Arab students in different stages of their university training completed the Psychological Maltreatment Subscale Questionnaire on teacher’s mistreatment while they were in school, and the Wong and Law EI Scale. The long-term emotional impact was measured using a tool developed especially for the study. Results revealed that 31% of the participants reported being mistreated by teachers at least once. The most reported long-term emotional impacts were feeling defensive, feeling a constant need to prove their worth, and fearing not to be perceived as lazy. Teacher mistreatment had significant long-term emotional impacts and was negatively correlated with EI. EI further acted as a significant mediator in the links between teacher mistreatment and its long-term emotional impact, with an indirect effect of .03. Raising awareness among teachers as to possible long-term emotional effects of abusive behaviors may help decrease mistreatment in the future. Determining the long-term impact of emotional mistreatment on social-emotional skills can help explain and prevent various types of negative outcomes in those students at a later stage in life.
Low Cost Filtration of Domestic Wastewater for Irrigation Purpose  [PDF]
Kiemde Maximilien Sosthene, Narcisse Gahi
World Journal of Engineering and Technology (WJET) , 2018, DOI: 10.4236/wjet.2018.63036
Abstract: Water scarcity in developing countries has forced farmers to use sewage as an alternative source of irrigation water. However, the usage of sewage for vegetable production has been known to cause excessive and often-unbalanced addition of nutrients hence posing a threat to food safety. The objective of this study was to determine the efficacy of slow sand filter and wetland plant in domestic wastewater treatment. To achieve this objective, samples were collected from the domestic wastewater collection pond within Jomo Kenyatta University of Agriculture and Technology (JKUAT). Laboratory tests were conducted on the collected samples and they revealed the presence of BOD, DO, pH, TDS, Sulfates, Chloride, Turbidity, Salinity, Conductivity, Alkalinity？and Coliform; whose values varied when compared with that of the parameters for standard irrigation water. This gave insight to the kind of treatments and filtration medium that were required to transform domestic wastewater into water fit for irrigation. A slow sand filter bed was designed and constructed using precisely six samples materials; sand, sand and wetland plants, gravel, gravel and wetland plants, mixture of gravel and sand, mixture of gravel and sand with wetland plants. These materials were used to identify the chemical and biological changes in domestic wastewater within a seven-day period. The water collected from the slow sand filter was tested, results showed that, of all six samples, slow sand filter using the mixture of gravel, sand with wetland plants had an average percentage efficient of 90% in removing all impurities from domestic wastewater thereby turning it into water suitable for irrigation. It is hoped that this study will provide a safe, easy, eco-friendly and cheap method of wastewater treatment while ensuring the sustainability of wastewater for irrigation and the expansion of green spaces in urban and peri-urban areas.
Nurses' Voluntary Turnover during Early Hospital Career as Predicted by Depressive Symptoms and Anxiety Symptoms
Meyrav Marom,Meni koslowsky
International Journal of Psychological Studies , 2012, DOI: 10.5539/ijps.v4n2p188
Abstract: Using a longitudinal design, this study examined the unique effects of depressive symptoms and of anxiety symptoms on voluntary turnover of nurses during the early stage of their hospital career. We hypothesized that depressive symptoms would negatively predict turnover and that anxiety symptoms would positively predict turnover after controlling for their common variance. We also hypothesized the same effects for depressive and anxiety symptoms when assessed as changes over time. We collected longitudinal data from 201 newly employed hospital nurses in 25 general hospitals who completed questionnaires with a time lag of about six months at Time 1 (T1) and Time 2 (T2). To gauge turnover, we used the official hospitals' records at Time 3 (T3), about one year after the study's T1. Logistic regressions were used to test our hypotheses. As expected, we found that T2 anxiety symptoms increased the odds of the nurses' turnover while T2 depressive symptoms decreased it. As expected, the higher the increase between T1 and T2 in depressive symptoms, the lower the odds of the nurses turnover. However, we did not support the expectation that the T1 to T2 changes in anxiety symptoms would predict turnover positively. We suggest that the unique content of depression and anxiety differ markedly in their effects on quitting behavior.
Kadec-Pelczynski decomposition for Haagerup L_p-spaces
Narcisse Randrianantoanina
Mathematics , 2000,
Abstract: Let M be a von Neumann algebra (not necessarily semi-finite). We provide a generalization of the classical Kadec-Pelczynski subsequence decomposition of bounded sequences in L^p[0,1] to the case of the Haagerup L^p-spaces (1\le p<\infty). In particular, we prove that if (\phi_n)_n is a bounded sequence in the predual M_* of M, then there exist a subsequence (\phi_{n_k})_k of (\phi_n)_n, a decomposition \phi_{n_k}= y_k+ z_k such that {y_k, k\ge 1} is relatively weaklycompact and the support projections s(z_k)\downarrow_k 0 (or similarly mutually disjoint). As an application, we prove that every non-reflexive subspace of the dual of any given C*-algebra (or Jordan triples) contains asymptotically isometric copies of l_1 and therefore fails the fixed point property for nonexpansive mappings. These generalize earlier results for the case of preduals of semi-finite von Neumann algebras.
Factorization of operators on $C^*$-algebras
Narcisse Randrianantoanina
Mathematics , 1997,
Abstract: Let $A$ be a $C^*$-algebra. It is shown that every absolutely summing operator from $A$ into $\ell_2$ factors through a Hilbert space operator that belongs to the 4-Schatten- von Neumann class. We also provide finite dimensinal examples that show that one can not improve the 4-Schatten-von Neumann class to $p$-Schatten von Neumann class for any $p<4$. As application, we prove that there exists a modulus of capacity $\epsilon \to N(\epsilon)$ so that if $A$ is a $C^*$-algebra and $T \in \Pi_1(A,\ell_2)$ with $\pi_1(T)\leq 1$, then for every $\epsilon >0$, the $\epsilon$-capacity of the image of the unit ball of $A$ under $T$ does not exceed $N(\epsilon)$. This aswers positively a question raised by Pe\l czynski.
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