bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluación del modo lingüístico escribir con posibilidad de revisión y corrección del texto
Authors: López Corral Alfonso , Acuña Meléndrez Karla Fabiola , Flores Aguirre Carlos Javier , Irigoyen Morales Juan José
Published: April 2020

En investigaciones sobre escritura se ha señalado que revisar y corregir los textos son aspectos fundamentales cuando se escribe. Se considera también que la manera en que escriben las personas puede estudiarse por medio de la habilitación lingüística, definida como la facilitación de un desempeño en modo lingüístico activo (señalar, escribir o hablar) como resultado de la exposición previa a un modo lingüístico reactivo (observar, leer o escuchar). Por ello, el objetivo de este estudio fue evaluar la exposición de estudiantes universitarios a los modos reactivos, sobre la habilitación lingüística del modo activo escribir y sobre la revisión y corrección cuando se les presenta de nueva cuenta el texto escrito. Los participantes, asignados a uno de tres grupos, primero escribieron un texto sobre el ciclo del agua, después fueron expuestos a uno de los tres modos lingüísticos reactivos, por último, se les presentó el texto escrito previamente sobre el ciclo del agua para su revisión y corrección. Los resultados mostraron puntajes más altos para los grupos expuestos a los modos leer y escuchar, seguidos por el grupo donde debían observar; no se encontró corrección de los textos. Los resultados se discuten en relación con investigaciones de habilitación lingüística y con aspectos necesarios para la revisión y corrección de textos.
Funcionamiento ejecutivo y desempeño lector en niños con y sin dificultades de lectura: Un estudio de seguimiento ocular
Authors: Mateus Moreno Angelica , Lara Díaz María Fernanda , Beltrán Rojas Judy Costanza
Published: April 2020

Introducción: Las funciones ejecutivas incluyen habilidades como la memoria de trabajo, el control inhibitorio, la planeación y la flexibilidad cognitiva. Estas habilidades, resultan fundamentales para el desarrollo de procesos cognitivos complejos como el aprendizaje de la lectoescritura, encontrando que aquellos niños con dificultades de lectura tienden a presentar un nivel menor en el rendimiento en tareas de funciones ejecutivas. Objetivo: Caracterizar el rendimiento en funciones ejecutivas y su relación con el nivel de lenguaje y lectura en niños de 8 a 12 años con dificultades de lectura y sus controles por edad y género en relación a los patrones de seguimiento visual. Método: Participantes: 9 niños con dificultades de lectura y 9 controles. Procedimiento: Se evaluó el nivel de lenguaje, funciones ejecutivas y lectura haciendo uso del Eye Tracker Tobii Tx300.  Se analizaron los mapas de calor, glaze plot y las áreas de interés. Resultados y Conclusiones: Los niños con dificultades de lectura presentan un nivel de desempeño menor en tareas de funciones ejecutivas especialmente en el control inhibitorio y la planeación, estando estas asociadas directamente con el nivel de lenguaje y el rendimiento lector. De igual forma, las métricas visuales a partir del uso del Eye Tracker permite corroborar estas fallas en el procesamiento en tiempo real frente a tareas que implican demandas cognitivas de alto nivel.
RETRACTED: microRNA-155 Modulates Hepatic Stellate Cell Proliferation, Apoptosis, and Cell Cycle Progression in Rats With Alcoholic Hepatitis via the MAPK Signaling Pathway Through Targeting SOCS1
Authors: Liu Dengtao , Han Ping , Gao Chunhai , Gao Wei , Yao Xiaocui , Liu Shulan
Published: April 2020

The aim of this study was to investigate the regulatory function of the non-coding microRNA-155 (miR-155) and suppressor of cytokine signaling 1 (SOCS1) in alcoholic hepatitis (AH) and its potential mechanism associated with the mitogen-activated protein kinase (MAPK) signaling pathway. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (ALB), total bilirubin (TBIL), malondialdehyde (MDA), and superoxide dismutase (SOD) were measured in a rat model of AH. The biological prediction website microRNA.org and dual-luciferase reporter gene assay were used to identify whether SOCS1 was a direct target of miR-155, and the effects of miR-155 and SOCS1 on the viability, cycle progression, and apoptosis of hepatic stellate cells were assessed using RT-qPCR, Western blot assay, MTT assay, Annexin V/PI double staining, and PI single staining. The levels of ALT, AST, MDA, and TBIL and the liver cell morphology were all prominently changed in AH model rats. miR-155 suppressed SOCS1 by specifically binding to SOCS1-3’-UTR to activate the MAPK signaling pathway. SOCS1 had low expression while miR-155 was highly expressed in AH rats. miR-155 promoted hepatic stellate cell viability and cycle progression and reduced cell apoptosis by silencing SOCS1. Together, we find that silenced miR-155 could upregulate SOCS1 and inactivate the MAPK signaling pathway, thereby inhibiting the proliferation of alcoholic hepatic stellate cells and promoting cell apoptosis.
Optimal Nitrogen Practice in Winter Wheat-Summer Maize Rotation Affecting the Fates of 15N-Labeled Fertilizer
Authors: Liang Haiyan , Shen Pengfei , Kong Xiangze , Liao Yuncheng , Liu Yang , Wen Xiaoxia
Published: April 2020

Lower nitrogen recovery efficiency (NRE) and negative environmental impacts caused by excessive nitrogen (N) fertilization threaten the sustainability of agriculture. Efficient and appropriate fertilization practices are extremely important to achieve higher crop yield with minimum N loss. A field microplot experiment was conducted in a wheat-maize rotation system in Shaanxi province, at North China Plain, using the 15N isotope tracer technique to qualify the different annual N managements in terms of crop yield, NRE, N distribution in plant-soil, and N losses to optimize the N management. The experiment included four N treatments: conventional practice with 510 kg ha−1 annually in four applications (N1), and three optimized N treatments, reducing N rate to 420 kg ha−1, adjusting topdressing fertilizer times and using slow-release fertilizer (SRF) (N2, N3, N4). The results showed that the grain yield and N uptake did not differ significantly among treatments. N from fertilizer taken up (Ndff) by wheat was not affected by N management; however, in maize, Ndff performed differently. Optimized treatments significantly decreased the Ndff as compared to N1 treatment. Furthermore, NRE of wheat and annual nitrogen recovery efficiency (annual NRE) did not differ among treatments in 2016 but significantly increased in 2017 compared to N1. Annual NRE in 2017 was similar to that obtained for wheat. For maize, optimized N managements decreased the NRE in N3 and N4 treatments of two years. Potential losses in wheat were also similar amongst treatments, but in maize, N3 and N4 had lower residual N in the soil’s top 60 cm but resulted in higher potential losses than N1 and N2. Overall, our results demonstrate that applying 420 kg N ha−1 annually in three applications and combining SRF and urea are effective to sustain crop yield, improve the efficiency of N usage by maize, and reduce N losses in this region.
Human AlphoidtetO Artificial Chromosome as a Gene Therapy Vector for the Developing Hemophilia A Model in Mice
Authors: Ponomartsev Sergey V. , Sinenko Sergey A. , Skvortsova Elena V. , Liskovykh Mikhail A. , Voropaev Ivan N. , Savina Maria M. , Kuzmin Andrey A. , Kuzmina Elena Yu. , Kondrashkina Alexandra M. , Larionov Vladimir , Kouprina Natalay , Tomilin Alexey N.
Published: April 2020

Human artificial chromosomes (HACs), including the de novo synthesized alphoidtetO-HAC, are a powerful tool for introducing genes of interest into eukaryotic cells. HACs are mitotically stable, non-integrative episomal units that have a large transgene insertion capacity and allow efficient and stable transgene expression. Previously, we have shown that the alphoidtetO-HAC vector does not interfere with the pluripotent state and provides stable transgene expression in human induced pluripotent cells (iPSCs) and mouse embryonic stem cells (ESCs). In this study, we have elaborated on a mouse model of ex vivo iPSC- and HAC-based treatment of hemophilia A monogenic disease. iPSCs were developed from FVIIIY/− mutant mice fibroblasts and FVIII cDNA, driven by a ubiquitous promoter, was introduced into the alphoidtetO-HAC in hamster CHO cells. Subsequently, the therapeutic alphoidtetO-HAC-FVIII was transferred into the FVIIIY/– iPSCs via the retro-microcell-mediated chromosome transfer method. The therapeutic HAC was maintained as an episomal non-integrative vector in the mouse iPSCs, showing a constitutive FVIII expression. This study is the first step towards treatment development for hemophilia A monogenic disease with the use of a new generation of the synthetic chromosome vector—the alphoidtetO-HAC.
Involvement of 27-Hydroxycholesterol in Mitotane Action on Adrenocortical Carcinoma
Authors: Germano Antonina , Rossin Daniela , Leoni Valerio , Iaia Noemi , Saba Laura , Basile Vittoria , Puglisi Soraya , Caccia Claudio , Poli Giuseppe , Biasi Fiorella , Terzolo Massimo
Published: April 2020

Adrenocortical carcinoma (ACC) is a rare cancer with poor prognosis. Mitotane, the standard treatment for ACC, impairs adrenocortical steroid biosynthesis and cholesterol metabolism. In the H295R cell line, a standard ACC in vitro model, mitotane was previously reported to enhance the production of some oxysterols. To verify the possible mechanistic involvement of oxysterols in the anti-ACC effect of mitotane, a gas chromatography mass spectrometry (GC-MS) profiling of oxysterols and the main cholesterol precursors was carried out in H295R cells. Among the oxysterols detected in mitotane-treated cells, 27OHC was markedly produced, as well as lanosterol and lathosterol cholesterol precursors. In this cell model, mitotane was confirmed to affect mitochondrial transmembrane potential and induce apoptosis. Such cytotoxic effects were perfectly matched by H295R cell treatment with a single identical micromolar amount of 27OHC. The mitotane-dependent strong increase in 27OHC was confirmed in vivo, in the plasma of ACC patients under treatment with the drug. Moreover, lanosterol, lathosterol, desmosterol and, to a minor extent, 24-hydroxycholesterol and 25-hydroxycholesterol plasma levels were significantly increased in those patients. The cytotoxic effect of mitotane on ACC cells may be partly related to the increased intracellular level of 27OHC induced by the drug itself.
Microautophagy in Plants: Consideration of Its Molecular Mechanism
Authors: Sieńko Katarzyna , Poormassalehgoo Andisheh , Yamada Kenji , Goto-Yamada Shino
Published: April 2020

Microautophagy is a type of autophagy. It is characterized by direct enclosing with the vacuolar/lysosomal membrane, which completes the isolation and uptake of cell components in the vacuole. Several publications present evidence that plants exhibit microautophagy. Plant microautophagy is involved in anthocyanin accumulation in the vacuole, eliminating damaged chloroplasts and degrading cellular components during starvation. However, information on the molecular mechanism of microautophagy is less available than that on the general macroautophagy, because the research focusing on microautophagy has not been widely reported. In yeast and animals, it is suggested that microautophagy can be classified into several types depending on morphology and the requirements of autophagy-related (ATG) genes. This review summarizes the studies on plant microautophagy and discusses possible techniques for a future study in this field while taking into account the information on microautophagy obtained from yeast and animals.
Molecular Chaperones in Cancer Stem Cells: Determinants of Stemness and Potential Targets for Antitumor Therapy
Authors: Kabakov Alexander , Yakimova Anna , Matchuk Olga
Published: April 2020

Cancer stem cells (CSCs) are a great challenge in the fight against cancer because these self-renewing tumorigenic cell fractions are thought to be responsible for metastasis dissemination and cases of tumor recurrence. In comparison with non-stem cancer cells, CSCs are known to be more resistant to chemotherapy, radiotherapy, and immunotherapy. Elucidation of mechanisms and factors that promote the emergence and existence of CSCs and their high resistance to cytotoxic treatments would help to develop effective CSC-targeting therapeutics. The present review is dedicated to the implication of molecular chaperones (protein regulators of polypeptide chain folding) in both the formation/maintenance of the CSC phenotype and cytoprotective machinery allowing CSCs to survive after drug or radiation exposure and evade immune attack. The major cellular chaperones, namely heat shock proteins (HSP90, HSP70, HSP40, HSP27), glucose-regulated proteins (GRP94, GRP78, GRP75), tumor necrosis factor receptor-associated protein 1 (TRAP1), peptidyl-prolyl isomerases, protein disulfide isomerases, calreticulin, and also a transcription heat shock factor 1 (HSF1) initiating HSP gene expression are here considered as determinants of the cancer cell stemness and potential targets for a therapeutic attack on CSCs. Various approaches and agents are discussed that may be used for inhibiting the chaperone-dependent development/manifestations of cancer cell stemness.
Key Components of Human Myofibre Denervation and Neuromuscular Junction Stability are Modulated by Age and Exercise
Authors: Soendenbroe Casper , Bechshøft Cecilie J. L. , Heisterberg Mette F. , Jensen Simon M. , Bomme Emma , Schjerling Peter , Karlsen Anders , Kjaer Michael , Andersen Jesper L. , Mackey Abigail L.
Published: April 2020

The decline in muscle mass and function with age is partly caused by a loss of muscle fibres through denervation. The purpose of this study was to investigate the potential of exercise to influence molecular targets involved in neuromuscular junction (NMJ) stability in healthy elderly individuals. Participants from two studies (one group of 12 young and 12 elderly females and another group of 25 elderly males) performed a unilateral bout of resistance exercise. Muscle biopsies were collected at 4.5 h and up to 7 days post exercise for tissue analysis and cell culture. Molecular targets related to denervation and NMJ stability were analysed by immunohistochemistry and real-time reverse transcription polymerase chain reaction. In addition to a greater presence of denervated fibres, the muscle samples and cultured myotubes from the elderly individuals displayed altered gene expression levels of acetylcholine receptor (AChR) subunits. A single bout of exercise induced general changes in AChR subunit gene expression within the biopsy sampling timeframe, suggesting a sustained plasticity of the NMJ in elderly individuals. These data support the role of exercise in maintaining NMJ stability, even in elderly inactive individuals. Furthermore, the cell culture findings suggest that the transcriptional capacity of satellite cells for AChR subunit genes is negatively affected by ageing.
Resistivity Characterization of Molybdenum-Coated Graphite-Based Substrates for High-Luminosity LHC Collimators
Authors: Accettura Carlotta , Amorim David , Antipov Alekseyevichx , Baris Adrienn , Bertarelli Alessandro , Biancacci Nicolò , Calatroni Sergio , Carra Federico , Caspers Fritz , García-Tabarés Valdivieso Elisa , Valenzuela Jorge , Kurtulus Adnan , Mereghetti Alessio , Métral Elias , Redaelli Stefano , Salvant Benoit , Taborelli Mauro , Vollenberg Wilhelmus
Published: April 2020

The High-Luminosity Large Hadron Collider (HL-LHC) project aims at extending the operability of the LHC by another decade and increasing by more than a factor of ten the integrated luminosity that the LHC will have collected by the end of Run 3. This will require doubling the beam intensity and reducing the transverse beam size compared to those of the LHC design. The higher beam brightness poses new challenges for machine safety, due to the large energy of 700 MJ stored in the beams, and for beam stability, mainly due to the collimator contribution to the total LHC beam coupling impedance. A rich research program was therefore started to identify suitable materials and collimator designs, not only fulfilling impedance reduction requirements but also granting adequate beam-cleaning and robustness against failures. The use of thin molybdenum coatings on a molybdenum–graphite substrate has been identified as the most promising solution to meet both collimation and impedance requirements, and it is now the baseline choice of the HL-LHC project. In this work we present the main results of the coating characterization, in particular addressing the impact of coating microstructure on the electrical resistivity with different techniques, from Direct Current (DC) to GHz frequency range.
Superconductivity in La2O2M4S6 -Type Bi-based Compounds: A Review on Element Substitution Effects
Authors: Jha Rajveer , Mizuguchi Yoshikazu
Published: April 2020

Since 2012, layered compounds containing Bi-Ch (Ch: S and Se) layers have been extensively studied in the field of superconductivity. The most-studied system is BiS2-based superconductors with two-layer-type conducting layers. Recently, superconductivity was observed in La2O2M2S6 (M = metals), which contains four-layer-type conducting layers. The four-layer-type Bi-based superconductors are new systems in the family of Bi-based superconductors; we can expect further development of Bi-based layered superconductors. In this review article, we summarize the progress of synthesis, structural analysis, investigations on superconducting properties, and material design of the four-layer-type Bi-based superconductors. In-plane chemical pressure is the factor essential for the emergence of bulk superconductivity in the system. The highest Tc of 4.1 K was observed in Rare Earth elements (RE) substituted La2-xRExO2Bi3Ag0.6Sn0.4S6.
Study on Optimization of Active Control Schemes for Considering Transient Processes in the Case of Pipeline Leakage
Authors: Zhang Wan , Shen Ruihao , Xu Ning , Zhang Haoran , Liang Yongtu
Published: April 2020

Pipeline leakage of crude oil, refined oil or other petroleum derivatives can cause serious damage to the environment, soil, and more importantly, pose a serious threat to personal safety. The losses can be minimized to a degree by active control. Therefore, timely and effective control measures should be taken to minimize the leak volume whenever a pipeline leaks. However, the complexity of pipeline hydraulic systems makes it difficult to optimize control schemes for pipeline hydraulic devices under leak conditions, and existing studies rarely consider complex transient processes. This paper aims to establish a mixed integer linear programming model considering transient processes, hydraulic constraints, equipment constraints and flow constraints, and develop a detailed control scheme of the devices by the branch and bound algorithm. Moreover, it is the objective of the model to figure out the most optimal control plan to minimize the leakage. Experiments on a real-world liquid pipeline have proved the practicability and high reliability of the model.
Data-Driven Modeling of Fuel Consumption for Turboprop-Powered Civil Airliners
Authors: Marinus Benoit G. , Hauglustaine Antoine
Published: April 2020

Next to empirical correlations for the specific range, fuel flow rate, and specific fuel consumption, a response surface model for estimates of the fuel consumption in early design stages is presented and validated. The response-surface’s coefficients are themselves predicted from empirical correlations based solely on the operating empty weight. The model and correlations are all derived from fuel consumption data of nine current civil turbo-propeller aircraft and are validated on a separate set. The model can accurately predict fuel weights of new designs for any combination of payload and range within the current range of efficiency of the propulsion. The accuracy of the model makes it suited for preliminary and conceptual design of near-in-kind turbo-propeller aircraft. The model can shorten the design cycle by delivering fast and accurate fuel weight estimates from the first design iteration once the operating empty weight is known. Since it is based solely on the operating empty weight and it is accurate, the model is a sound variant to the Breguet range equation in order to make accurate fuel weight estimates.
Fault Ride Through Capability Improvement of DFIG Based Wind Farm Using Nonlinear Controller Based Bridge-Type Flux Coupling Non-Superconducting Fault Current Limiter
Authors: Islam Md. Rashidul , Huda Md. Najmul , Hasan Jakir , Sadi Mohammad Ashraf Hossain , AbuHussein Ahmed , Roy Tushar Kanti , Mahmud Md. Apel
Published: April 2020

High penetration of Doubly Fed Induction Generator (DFIG) into existing power grid can attribute complex issues as they are very sensitive to the grid faults. In addition, Fault Ride Through (FRT) is one of the main requirements of the grid code for integrating Wind Farms (WFs) into the power grid. In this work, to enhance the FRT capability of the DFIG based WFs, a Bridge-Type Flux Coupling Non-Superconducting Fault Current Limiter (BFC-NSFCL) is proposed. The effectiveness of the proposed BFC-NSFCL is evaluated through performance comparison with that of the Bridge-Type Fault Current Limiter (BFCL) and Series Dynamic Braking Resistor (SDBR). Moreover, a dynamic nonlinear controller is also proposed for controlling the operation of the BFC-NSFCL. Extensive simulations are carried out in the MATLAB/SIMULINK environment for both symmetrical and unsymmetrical temporary as well as permanent faults. Based on the simulation results and different numerical analysis, it is found that the proposed nonlinear controller based BFC-NSFCL is very effective in enhancing the FRT capability of the WF. Also, the BFC-NSFCL outperforms the conventional BFCL and SDBR by maintaining a near-seamless performance during various grid fault situations.
Real-Time Active-Reactive Optimal Power Flow with Flexible Operation of Battery Storage Systems
Authors: Mohagheghi Erfan , Alramlawi Mansour , Gabash Aouss , Blaabjerg Frede , Li Pu
Published: April 2020

In this paper, a multi-phase multi-time-scale real-time dynamic active-reactive optimal power flow (RT-DAR-OPF) framework is developed to optimally deal with spontaneous changes in wind power in distribution networks (DNs) with battery storage systems (BSSs). The most challenging issue hereby is that a large-scale ‘dynamic’ (i.e., with differential/difference equations rather than only algebraic equations) mixed-integer nonlinear programming (MINLP) problem has to be solved in real time. Moreover, considering the active-reactive power capabilities of BSSs with flexible operation strategies, as well as minimizing the expended life costs of BSSs further increases the complexity of the problem. To solve this problem, in the first phase, we implement simultaneous optimization of a huge number of mixed-integer decision variables to compute optimal operations of BSSs on a day-to-day basis. In the second phase, based on the forecasted wind power values for short prediction horizons, wind power scenarios are generated to describe uncertain wind power with non-Gaussian distribution. Then, MINLP AR-OPF problems corresponding to the scenarios are solved and reconciled in advance of each prediction horizon. In the third phase, based on the measured actual values of wind power, one of the solutions is selected, modified, and realized to the network for very short intervals. The applicability of the proposed RT-DAR-OPF is demonstrated using a medium-voltage DN.
Thermal Comfort Aspects of Solar Gains during the Heating Season
Authors: Kalmár Ferenc , Kalmár Tünde
Published: April 2020

Glazing plays a key role in the energy balance of buildings. The aim of this paper is to enlighten the thermal discomfort caused by large glazed areas in the heating season and to point out a possible solution that can provide proper thermal comfort with low energy use. It is unusual to discuss the negative effects of solar gains on thermal comfort during the heating season. However, there are cases when glazing may lead to unforeseen indoor thermal discomfort conditions. Laboratory and on site measurements were performed in order to assess thermal discomfort caused by direct and diffuse radiation. It was shown that the WBGT (Wet Bulb Globe Temperature) index may exceed even 30 °C in the winter season in a room having large glazed area oriented to east. Laboratory tests performed in climate chamber have shown that the high PMV values cannot be reduced below 1.0, increasing the air change rate in the room. Using opaque drapes, the WBGT index was reduced by 2 °C, but the daylighting decreased substantially. It was demonstrated that by using advanced personalized ventilation systems, the appropriate thermal comfort can be provided avoiding the reduction of daylighting.
Vehicle-To-Grid for Peak Shaving to Unlock the Integration of Distributed Heat Pumps in a Swedish Neighborhood
Authors: Arnaudo Monica , Topel Monika , Laumert Björn
Published: April 2020

The city of Stockholm is close to hitting the capacity limits of its power grid. As an additional challenge, electricity has been identified as a key resource to help the city to meet its environmental targets. This has pushed citizens to prefer power-based technologies, like heat pumps and electric vehicles, thus endangering the stability of the grid. The focus of this paper is on the district of Hammarby Sjöstad. Here, plans are set to switch from district heating to heat pumps. A previous study verified that this choice will cause overloadings on the electricity distribution grid. The present paper tackles this problem by proposing a new energy storage option. By considering the increasing share of electric vehicles, the potential of using the electricity stored in their batteries to support the grid is explored through technical performance simulations. The objective was to enable a bi-directional flow and use the electric vehicles’ (EVs)’ discharging to shave the peak demand caused by the heat pumps. It was found that this solution can eliminate overloadings up to 50%, with a 100% EV penetration. To overcome the mismatch between the availability of EVs and the overloadings’ occurrence, the minimum state of charge for discharging should be lower than 70%.
A Bi-Layer Multi-Objective Techno-Economical Optimization Model for Optimal Integration of Distributed Energy Resources into Smart/Micro Grids
Authors: Rezaeimozafar Mostafa , Eskandari Mohsen , Amini Mohammad Hadi , Moradi Mohammad Hasan , Siano Pierluigi
Published: April 2020

The energy management system is executed in microgrids for optimal integration of distributed energy resources (DERs) into the power distribution grids. To this end, various strategies have been more focused on cost reduction, whereas effectively both economic and technical indices/factors have to be considered simultaneously. Therefore, in this paper, a two-layer optimization model is proposed to minimize the operation costs, voltage fluctuations, and power losses of smart microgrids. In the outer-layer, the size and capacity of DERs including renewable energy sources (RES), electric vehicles (EV) charging stations and energy storage systems (ESS), are obtained simultaneously. The inner-layer corresponds to the scheduled operation of EVs and ESSs using an integrated coordination model (ICM). The ICM is a fuzzy interface that has been adopted to address the multi-objectivity of the cost function developed based on hourly demand response, state of charges of EVs and ESS, and electricity price. Demand response is implemented in the ICM to investigate the effect of time-of-use electricity prices on optimal energy management. To solve the optimization problem and load-flow equations, hybrid genetic algorithm (GA)-particle swarm optimization (PSO) and backward-forward sweep algorithms are deployed, respectively. One-day simulation results confirm that the proposed model can reduce the power loss, voltage fluctuations and electricity supply cost by 51%, 40.77%, and 55.21%, respectively, which can considerably improve power system stability and energy efficiency.
Development and Performance Assessment of Prefabricated Insulation Elements for Deep Energy Renovation of Apartment Buildings
Authors: Pihelo Peep , Kuusk Kalle , Kalamees Targo
Published: April 2020

A need for the refurbishment and renewal of the existing building stock has been in focus for many decades, principally because of excessive global energy consumption and pollution. This paper presents a methodology and the results of analysis of choices of realizable sets of timber frame prefabricated insulation elements for major renovation of apartment buildings. Numerous combinations of elements with different characteristics were analyzed by applying measurements, interviews, and building performance simulation software, and thereupon their performance, installation eligibility, and concurrent cost levels were compared. Mineral wool board with a special wind barrier facing was found to be the best material as a wind barrier from the perspective of hygrothermal performance. An air and vapor barrier should have sufficient vapor permeability to allow dry-out of constructional moisture. It is possible to renovate apartment buildings to meet the nZEB energy performance requirements and their moisture safety can be guaranteed without paying high relative difference cost. Calculations showed that the global cost was lower for solutions with some mold growth risk. Great care is needed when decreasing costs without simultaneous hygrothermal analyses. The facade cladding was found to have the highest influence on the initial cost of the prefabricated insulation element.
AC Volume Breakdown and Surface Flashover of a 4% NovecTM 4710/96% CO2 Gas Mixture Compared to CO2 in Highly Nonhomogeneous Fields
Authors: Nechmi Houssem Eddine , Slama Mohammed El Amine , Haddad Abderrahmane (Manu) , Wilson Gordon
Published: April 2020

AC pre-discharge currents, breakdown, and flashover voltage measurements are reported in a 10 mm needle-plane arrangement in a 4% NovecTM 4710/96% CO2 gas mixture and compared with CO2 for pressures up to 8.8 bar abs. Flashover measurements were performed on different solid dielectrics (Al2O3_filled epoxy resins, PTFE (Polytetrafluoroethylene) and PE (polyethylene)) for different roughness surface finishes. The effect of fixed conducting needles at various positions on electrical strength is reported. A strong nonlinear behaviour as function of gas pressure was observed for all the studied parameters (gas, needle position, solid insulator, insulator roughness). The non-linear behaviour is attributed to the inception and quenching of glow corona, in the interval between inception and breakdown or flashover voltages. It is found that a 4% concentration of NovecTM 4710 in CO2 has a breakdown/flashover voltage ≈ 1.14 higher than CO2. The glow corona-induced stabilization effect is seen for pressures between 2 and 5 bar abs for all the studied parameters. The peak flashover voltage and its associated pressure of the different insulators are strongly dependent on surface roughness. At 8.8 bar abs, the flashover voltage level obtained with various materials was ordered as follows: PTFE > PE-UHMW > Epoxy > HDPE(High-density polyethylene).
Design Method of Dual Active Bridge Converters for Photovoltaic Systems with High Voltage Gain
Authors: Henao-Bravo Elkin Edilberto , Ramos-Paja Carlos Andrés , Saavedra-Montes Andrés Julián , González-Montoya Daniel , Sierra-Pérez Julián
Published: April 2020

In this paper, a design method for a photovoltaic system based on a dual active bridge converter and a photovoltaic module is proposed. The method is supported by analytical results and theoretical predictions, which are confirmed with circuital simulations. The analytical development, the theoretical predictions, and the validation through circuital simulations, are the main contributions of the paper. The dual active bridge converter is selected due to its high efficiency, high input and output voltages range, and high voltage-conversion ratio, which enables the interface of low-voltage photovoltaic modules with a high-voltage dc bus, such as the input of a micro-inverter. To propose the design method, the circuital analysis of the dual active bridge converter is performed to describe the general waveforms derived from the circuit behavior. Then, the analysis of the dual active bridge converter, interacting with a photovoltaic module driven by a maximum power point tracking algorithm, is used to establish the mathematical expressions for the leakage inductor current, the photovoltaic current, and the range of operation for the phase shift. The design method also provides analytical equations for both the high-frequency transformer equivalent leakage inductor and the photovoltaic side capacitor. The design method is validated through detailed circuital simulations of the whole photovoltaic system, which confirm that the maximum power of the photovoltaic module can be extracted with a correct design of the dual active bridge converter. Also, the theoretical restrictions of the photovoltaic system, such as the photovoltaic voltage and power ripples, are fulfilled with errors lower than 2% with respect to the circuital simulations. Finally, the simulation results also demonstrate that the maximum power point for different environmental conditions is reached, optimizing the phase shift factor with a maximum power point tracking algorithm.
Analytical Solution for Coupled Diffusion Induced Stress Model for Lithium-Ion Battery
Authors: Clerici Davide , Mocera Francesco , Somà Aurelio
Published: April 2020

Electric cycling is one of the major damage sources in lithium-ion batteries and extensive work has been produced to understand and to slow down this phenomenon. The damage is related to the insertion and extraction of lithium ions in the active material. These processes cause mechanical stresses which in turn generate crack propagation, material loss and pulverization of the active material. In this work, the principles of diffusion induced stress theory are applied to predict concentration and stress field in the active material particles. Coupled and uncoupled models are derived, depending on whether the effect of hydrostatic stress on concentration is considered or neglected. The analytical solution of the coupled model is proposed in this work, in addition to the analytical solution of the uncoupled model already described in the literature. The analytical solution is a faster and simpler way to deal with the problem which otherwise should be solved in a numerical way with finite difference method or a finite element model. The results of the coupled and uncoupled models for three different state of charge levels are compared assuming the physical parameters of anode and cathode active material. Finally, the effects of tensile and compressive stress are analysed.
A Mixed Binary Linear Programming Model for Optimal Energy Management of Smart Buildings
Authors: Foroozandeh Zahra , Ramos Sérgio , Soares João , Lezama Fernando , Vale Zita , Gomes António , L. Joench Rodrigo
Published: April 2020

Efficient alternatives in energy production and consumption are constantly being investigated and conducted by increasingly strict policies. Buildings have a significant influence on electricity consumption, and their management may contribute to the sustainability of the electricity sector. Additionally, with growing incentives in the distributed generation (DG) and electric vehicle (EV) industries, it is believed that smart buildings (SBs) can play a key role in sustainability goals. In this work, an energy management system is developed to reduce the power demands of a residential building, considering the flexibility of the contracted power of each apartment. In order to balance the demand and supply, the electrical power provided by the external grid is supplemented by microgrids such as battery energy storage systems (BESS), EVs, and photovoltaic (PV) generation panels. Here, a mixed binary linear programming formulation (MBLP) is proposed to optimize the scheduling of the EVs charge and discharge processes and also those of BESS, in which the binary decision variables represent the charging and discharging of EVs/BESS in each period. In order to show the efficiency of the model, a case study involving three scenarios and an economic analysis are considered. The results point to a 65% reduction in peak load consumption supplied by an external power grid and a 28.4% reduction in electricity consumption costs.
Investigation of NiFe-Based Catalysts for Oxygen Evolution in Anion-Exchange Membrane Electrolysis
Authors: Campagna Zignani Sabrina , Lo Faro Massimiliano , Trocino Stefano , Aricò Antonino Salvatore
Published: April 2020

NiFe electrodes are developed for the oxygen evolution reaction (OER) in an alkaline electrolyser based on an anion exchange membrane (AEM) separator and fed with diluted KOH solution as supporting electrolyte. This study reports on the electrochemical behaviour of two different NiFe-oxide compositions (i.e., Ni1Fe1-oxide and Ni1Fe2-oxide) prepared by the oxalate method. These catalysts are assessed for single-cell operation in an MEA including a Sustainion™ anion-exchange membrane. The electrochemical polarization shows a current density of 650 mA cm−2 at 2 V and 50 °C for the Ni1Fe1 anode composition. A durability test of 500 h is carried out using potential cycling as an accelerated stress-test. This shows a decrease in current density of 150 mA cm−2 mainly during the first 400 h. The performance achieved for the anion-exchange membrane electrolyser single-cell based on the NiFeOx catalyst appears promising. However, further improvements are required to enhance the stability under these operating conditions.
Towards Smart Energy Grids: A Box-Constrained Nonlinear Underdetermined Model for Power System Observability Using Recursive Quadratic Programming
Authors: Theodorakatos Nikolaos P. , Lytras Miltiadis , Babu Rohit
Published: April 2020

This paper introduces an underdetermined nonlinear programming model where the equality constraints are fewer than the design variables defined on a compact set for the solution of the optimal Phasor Measurement Unit (PMU) placement. The minimization model is efficiently solved by a recursive quadratic programming (RQP) method. The focus of this work is on applying an RQP to attempt to find guaranteed global minima. The proposed minimization model is conducted on IEEE systems. For all simulation runs, the RQP converges superlinearly towards optimality in a finite number of iterations without to be rejected the full step-length. The simulation results indicate that the RQP finds out the minimal number and the optimal locations of PMUs to make the power system wholly observable.
Experimental and Theoretical Study on the Critical Breaking Velocity of Marine Natural Gas Hydrate Sediments Breaking by Water Jet
Authors: Wang Leizhen , Wang Guorong
Published: April 2020

Water jet technology is a key technology in the marine natural gas hydrate (NGH) solid fluidization mining method. As an important parameter in water jet breaking NGH sediments technology, the critical breaking velocity of NGH sediments is unknown. In the present research, an orthogonal design experiment is carried out to study the critical velocity of NGH breakage by water jet, using frozen soil and sand as experimental samples. First, the time it takes to reach maximum NGH breaking depth is determined. Then, ultimate breaking distance is studied with respect to the NGH saturation, jet pressure, and nozzle diameter. Following that, the variation of critical velocity with NGH saturation is analyzed. Eventually, a formula to calculate the critical velocity for marine NGH breakage by water jet process is established, and the undetermined coefficient (η) in the formula is calibrated with the experiment data. The results show that the ultimate breaking distance is mostly achieved within 63 s. The three experimental factors in order of the effect on the ultimate breaking depth (from high to low) are NGH saturation, jet pressure, and nozzle diameter. The critical velocities for marine NGH breakage corresponding to the NGH saturations of 20%, 40,%, 6%, and 80% are 5.71 m/s, 7.14 m/s, 9.60 m/s, and 10.85 m/s, respectively. The undetermined coefficient η in critical velocity formula is 1.44 m/s.
Investigation of Pressure Fluctuation and Pulsating Hydraulic Axial Thrust in Francis Turbines
Authors: Zhou Xing , Shi Changzheng , Miyagawa Kazuyoshi , Wu Hegao , Yu Jinhong , Ma Zhu
Published: April 2020

Under the circumstances of rapid expansion of diverse forms of volatile and intermittent renewable energy sources, hydropower stations have become increasingly indispensable for improving the quality of energy conversion processes. As a consequence, Francis turbines, one of the most popular options, need to operate under off-design conditions, particularly for partial load operation. In this paper, a prototype Francis turbine was used to investigate the pressure fluctuations and hydraulic axial thrust pulsation under four partial load conditions. The analyses of pressure fluctuations in the vaneless space, runner, and draft tube are discussed in detail. The observed precession frequency of the vortex rope is 0.24 times that of the runner rotational frequency, which is able to travel upstream (from the draft tube to the vaneless space). Frequencies of both 24.0 and 15.0 times that of the runner rotational frequency are detected in the recording points of the runner surface, while the main dominant frequency recorded in the vaneless zone is 15.0 times that of the runner rotational frequency. Apart from unsteady pressure fluctuations, the pulsating property of hydraulic axial thrust is discussed in depth. In conclusion, the pulsation of hydraulic axial thrust is derived from the pressure fluctuations of the runner surface and is more complicated than the pressure fluctuations.
Two-Layer Ensemble-Based Soft Voting Classifier for Transformer Oil Interfacial Tension Prediction
Authors: Nayyar Hassan Ahmad , El-Hag Ayman
Published: April 2020

This paper uses a two-layered soft voting-based ensemble model to predict the interfacial tension (IFT), as one of the transformer oil test parameters. The input feature vector is composed of acidity, water content, dissipation factor, color and breakdown voltage. To test the generalization of the model, the training data was obtained from one utility company and the testing data was obtained from another utility. The model results in an optimal accuracy of 0.87 and a F1-score of 0.89. Detailed studies were also carried out to find the conditions under which the model renders optimal results.
Small-Sized Pulsating Heat Pipes/Oscillating Heat Pipes with Low Thermal Resistance and High Heat Transport Capability
Authors: Winkler Markus , Rapp David , Mahlke Andreas , Zunftmeister Felix , Vergez Marc , Wischerhoff Erik , Clade Jürgen , Bartholomé Kilian , Schäfer-Welsen Olaf
Published: April 2020

Electronics (particularly power electronics) are the core element in many energy-related applications. Due to the increasing power density of electronic parts, the demands on thermal management solutions have risen considerably. As a novel passive and highly efficient cooling technology, pulsating heat pipes (PHPs) can transfer heat away from critical hotspots. In this work, we present two types of small and compact PHPs with footprints of 50 × 100 mm2, thicknesses of 2 and 2.5 mm and with high fluid channel density, optimized for cooling electronic parts with high power densities. The characterization of these PHPs was carried out with a strong relation to practical applications, revealing excellent thermal properties. The thermal resistance was found to be up to 90% lower than that of a comparable solid copper plate. Thus, a hot part with defined heating power would remain at a much lower temperature level and, for the same heater temperature, a much larger heating power could be applied. Moreover, the dependence of PHP operation and thermal properties on water and air cooling, condenser area size and orientation is examined. Under some test configurations, dryout conditions are observed which could be avoided by choosing an appropriate size for the fluid channels, heater and condenser.
Optimal Design of a Stand-Alone Residential Hybrid Microgrid System for Enhancing Renewable Energy Deployment in Japan
Authors: Yoshida Yuichiro , Farzaneh Hooman
Published: April 2020

This paper aims at the optimal designing of a stand-alone microgrid (PV/wind/battery/diesel) system, which can be utilized to meet the demand load requirements of a small residential area in Kasuga City, Fukuoka. The simulation part is developed to estimate the electrical power generated by each component, taking into account the variation of the weather parameters, such as wind, solar irradiation, and ambient temperature. The optimal system design is then based on the Particle Swarm Optimization (PSO) method to find the optimal configuration of the proposed system, using the least-cost perspective approach.
A Sliding Mode Control Strategy with Repetitive Sliding Surface for Shunt Active Power Filter with an LCLCL Filter
Authors: Gao Yunguang , Li Xiaofan , Zhang Wenjie , Hou Dianchao , Zheng Lijun
Published: April 2020

This paper proposes a novel sliding mode control (SMC) scheme with a repetitive sliding surface for shunt active power filters (SAPF) to enhance the system robustness and eliminate harmonic current tracking errors. Traditional control schemes, such as PI control, repetitive control (RC), proportional resonance control (PR), improve the stability of the SAPF in the stable grid to a certain extent. However, the robustness of the SAPF control system has not been improved. In this paper, the SMC is applied to SAPF, and a sliding mode controller is constructed by using a linear sliding mode surface composed of the system state variables and a fast exponential power-reaching law, which can effectively enhance the system robustness. When the grid parameters change or external disturbances exist, sliding surface drift and sliding mode chattering will occur. Although fast-tracking of the harmonic current can still be achieved, it is difficult to accurately compensate AC harmonic current. Moreover, this may cause the harmonic current compensation error to be amplified. RC can achieve infinite gain at multiples of the fundamental frequency and can track inputs without static errors. In order to fully eliminate the harmonic current tracking error and effectively suppress the total harmonic distortion (THD) of the grid, the sliding mode surface was modified. An RC term of harmonic current error is introduced to the sliding mode surface, and a novel plugin-repetitive sliding mode control strategy (RCSMC) for SAPF is proposed. Finally, simulation and experiment results on the LCLCL-filter based SAPF show the effectiveness of the proposed control strategy.