Search

For the analyst, experiment is the most important stage in many fundamental and applied research. In order to study the object as much as possible and learn about the complex of its properties, it is necessary to investigate it, namely: to carry out experimental researches and to record the results of these studies on the media. This is necessary to compare the achieved level of knowledge of the object with that of the researcher in the process of literary and patent searches. In the future, the knowledge gained during the experimental research is used for practical purposes. This is the main task of scientific search. In turn, the effectiveness of experimental research largely depends on the methodology used in the process of scientific research.The researcher's attention should be focused on at least three aspects of carrying out the search work, at the expense of which it is possible to save considerable time and material resources and, at the same time, to obtain the desired results.In the first stage, it should be noted that the study of the state of technological systems for the production of semi-finished products, paper and cardboard shows that the individual blocks of such technological systems, and therefore the whole technological system is affected by the mass of independent deterministic values, called factors. These factors exert their influence in the process of mass preparation, including the stage of dissolution; cleaning; grinding; composing the composition; casting; pressing, drying of a cloth. After all, the production of paper or cardboard is a sequence of interrelated processes, which, in the long run, ultimately depend on the quality of the products being manufactured.In order to effectively reduce the number of factors that exert their influence, it is advisable for the experimenter to make a preliminary assessment of the influence of each of the factors identified in the literature and patent searches, and to form a group of the most significant factors on this basis. In the future, these factors will be involved in the next stages of experimental research. However, intuitive selection of significant factors is quite subjective and may lead to erroneous conclusions from the results of the analysis of the research results. Therefore, at the stage of preliminary research it is recommended to use statistical methods of selection of factors, namely: methods of expert assessments. These methods are based on the statistical processing of data obtained from a survey of specialists in the field of knowledge or analysis of scientific research. Expert assessments are based on the results of the most recent and unpublished scientific works performed by each expert.Despite their subjectivity, peer reviews provide useful, objective information. This information makes it possible to evaluate the impact of each factor under study. Using this method, the opinion of the expert group is considered to be more reliable than the opinion of the individual expert. The method is based on the fact that the unknown characteristic of the studied phenomenon is treated as a random variable, and each expert's individual assessment of the truth and significance of an event is a reflection of its law of distribution.In the second stage of research, an important aspect is to achieve maximum informativeness of the experiment. It is known that in the course of experimental research, the object under study responds differently to changing factors (one or more simultaneously) and, thus, exhibits its complex of properties. The task of the researcher is to plan the experimental studies so that the object in the course of its research maximally manifested its entire complex of properties, regardless of the internal structure of the investigated object, as well as the influence of these or other factors. Thus, the maximum reliability of the results of experimental studies in the conditions of random "noise" interference is ensured. Subsequently, multicriteria analysis of the basic plans and local transformations of each of them are carried out in order to select the most suitable for implementation at the request of the researcher. This is the second aspect of the methodology.The third, and very important, aspect of research methodology is the development of adequate mathematical models [4], on the basis of which a favorable field is created for modeling and finding optimal conditions with the use of computer technologies. At this stage, taking into account the complexity of technological systems for the production of semi-finished products, paper and cardboard, a number of adequate mathematical models, suitable for modeling purposes, have been created.Further stages of research work are the use of created mathematical models for modeling purposes. The task is to predict the levels of pollution of water flows of complex technological systems of paper and cardboard production with water-soluble organic, as well as mineral components under conditions of reduction of fresh water consumption from 40 m3 \ t to 10 m3\ t. This will give you an opportunity to determine the initial semi-finished products, a complex of auxiliary chemicals, as well as with the scheme of return water use., Розроблено методологію, яка дозволяє передбачити значення параметрів оптимізації у станах (точках факторного простору), що не досліджувалися в процесі проведення експерименту. Моделювання відбувається на базі комплексу адекватних математичних моделей, які створені на основі попередньо проведених експериментальних досліджень. Моделюванню піддаються процеси екстракції водорозчинних органічних речовин із волокнистих напівфабрикатів в процесах виробництва паперу та картону з мінімальним споживанням свіжої води.

The process of “hysteresis” has widely attracted the attention of researchers and investigators due to its usage in many disciplines of science and engineering. Economics, physics, chemistry, electrical, mechanical, and petroleum engineering are some examples of disciplines that encounter hysteresis. However, the meaning of hysteresis varies from one field to another, and therefore, many definitions occur for this phenomenon depending on the area of interest. The “hysteresis” phenomenon in petroleum engineering has gained the attention of researchers and investigators lately, because of the role that plays in reservoir engineering and reservoir simulation. Hysteretic effects influence reservoir performance. Therefore, an accurate estimation of rock and fluid property curves has an essential role in evaluating hydrocarbon recovery processes. In this paper, a comprehensive review of research and growth on the hysteresis of wettability for its applications in petroleum engineering is reported. Also, theoretical and experimental investigations of hysteresis of wettability are compared and discussed in detail. The review highlights a range of concepts in existing models and experimental processes for wettability hysteresis. Furthermore, this paper tracks the current development of hysteresis and provides insight for future trends in the research. Finally, it reveals an outlook on the research challenges and weaknesses of hysteresis of wettability.

The importance of adsorption-based biochemical/biological sensors in biochemistry and biophysics is paramount. Their temporal response gives information about the presence of a biochemical/biological analyte, its concentration and its interactions with the adsorption sites (which may be an integral part of the surface itself or immobilized functionalizing molecules). Mathematical models of the temporal response taking into account as many relevant effects as possible are essential for obtaining reliable information. We present a novel model taking into account the bimodal affinity of a sensing surface (adsorption occurs on two distinct site types), and the adsorption-caused depletion of the analyte from the sample. We perform qualitative and quantitative analysis of the analyte depletion influence on the bimodal adsorption, and of the influence of the sensing surface inhomogeneity on the sensor temporal response, for different analyte concentrations and different fractions of two types of adsorption sites. Since the presented mathematical model deals with the realistic cases of the sensing surface non-uniformity and the finite amount of analyte present in the sensor reaction chamber, it enables improved accuracy in interpreting the measurement data. Our results are general, i.e. valid for any adsorption sensor (microcantilevers, plasmonics) and for arbitrary sensor dimensions.

Розроблено методологію, яка дозволяє передбачити значення параметрів оптимізації у станах (точках факторного простору), що не досліджувалися в процесі проведення експерименту. Моделювання відбувається на базі комплексу адекватних математичних моделей, які створені на основі попередньо проведених експериментальних досліджень. Моделюванню піддаються процеси екстракції водорозчинних органічних речовин із волокнистих напівфабрикатів в процесах виробництва паперу та картону з мінімальним споживанням свіжої води. For the analyst, experiment is the most important stage in many fundamental and applied research. In order to study the object as much as possible and learn about the complex of its properties, it is necessary to investigate it, namely: to carry out experimental researches and to record the results of these studies on the media. This is necessary to compare the achieved level of knowledge of the object with that of the researcher in the process of literary and patent searches. In the future, the knowledge gained during the experimental research is used for practical purposes. This is the main task of scientific search. In turn, the effectiveness of experimental research largely depends on the methodology used in the process of scientific research. The researcher's attention should be focused on at least three aspects of carrying out the search work, at the expense of which it is possible to save considerable time and material resources and, at the same time, to obtain the desired results. In the first stage, it should be noted that the study of the state of technological systems for the production of semifinished products, paper and cardboard shows that the individual blocks of such technological systems, and therefore the whole technological system is affected by the mass of independent deterministic values, called factors. These factors exert their influence in the process of mass preparation, including the stage of dissolution; cleaning; grinding; composing the composition; casting; pressing, drying of a cloth. After all, the production of paper or cardboard is a sequence of interrelated processes, which, in the long run, ultimately depend on the quality of the products being manufactured. In order to effectively reduce the number of factors that exert their influence, it is advisable for the experimenter to make a preliminary assessment of the influence of each of the factors identified in the literature and patent searches, and to form a group of the most significant factors on this basis. In the future, these factors will be involved in the next stages of experimental research. However, intuitive selection of significant factors is quite subjective and may lead to erroneous conclusions from the results of the analysis of the research results. Therefore, at the stage of preliminary research it is recommended to use statistical methods of selection of factors, namely: methods of expert assessments. These methods are based on the statistical processing of data obtained from a survey of specialists in the field of knowledge or analysis of scientific research. Expert assessments are based on the results of the most recent and unpublished scientific works performed by each expert. Despite their subjectivity, peer reviews provide useful, objective information. This information makes it possible to evaluate the impact of each factor under study. Using this method, the opinion of the expert group is considered to be more reliable than the opinion of the individual expert. The method is based on the fact that the unknown characteristic of the studied phenomenon is treated as a random variable, and each expert's individual assessment of the truth and significance of an event is a reflection of its law of distribution. In the second stage of research, an important aspect is to achieve maximum informativeness of the experiment. It is known that in the course of experimental research, the object under study responds differently to changing factors (one or more simultaneously) and, thus, exhibits its complex of properties. The task of the researcher is to plan the experimental studies so that the object in the course of its research maximally manifested its entire complex of properties, regardless of the internal structure of the investigated object, as well as the influence of these or other factors. Thus, the maximum reliability of the results of experimental studies in the conditions of random "noise" interference is ensured. Subsequently, multicriteria analysis of the basic plans and local transformations of each of them are carried out in order to select the most suitable for implementation at the request of the researcher. This is the second aspect of the methodology. The third, and very important, aspect of research methodology is the development of adequate mathematical models [4], on the basis of which a favorable field is created for modeling and finding optimal conditions with the use of computer technologies. At this stage, taking into account the complexity of technological systems for the production of semi-finished products, paper and cardboard, a number of adequate mathematical models, suitable for modeling purposes, have been created. Further stages of research work are the use of created mathematical models for modeling purposes. The task is to predict the levels of pollution of water flows of complex technological systems of paper and cardboard production with water-soluble organic, as well as mineral components under conditions of reduction of fresh water consumption from 40 m3 \ t to 10 m3 \ t. This will give you an opportunity to determine the initial semi-finished products, a complex of auxiliary chemicals, as well as with the scheme of return water use.

COVID-19 dynamics is one of the most relevant subjects nowadays, and, in this regard, mathematical modeling and numerical simulations are of special interest. This paper describes COVID-19 dynamics based on a novel version of the susceptible–exposed–infectious–removed model. Removed population is split into recovered and death populations allowing a better comprehension of real situations. Besides, the total population is reduced based on the number of deaths. Hospital infrastructure is also included into the mathematical description allowing the consideration of collapse scenarios. Initially, a model verification is carried out calibrating system parameters with data from China outbreak that is considered a benchmark due the availability of data for the entire cycle. Afterward, Brazil outbreak is of concern, calibrating the model and developing numerical simulations. Results show several scenarios highlighting the importance of social isolation and hospital infrastructure. System dynamics has a strong sensitivity to transmission rate showing the importance of numerical simulations to guide public health decision strategies. Results also show that complex dynamical responses can emerge due to the oscillations of the transmission rate, being associated with distinct infection subsequent waves.

Filtering paper materials (FPM), which are easy to recycle, are widely applied to water purification. The main disadvantage of the absolute majority of filtering materials, including paper, is their tendency to biofouling. This drawback considerably limits or even sometimes makes it impossible to use filtering materials and/or sorbents in a certain medium. In connection with the above, the object of our study was the process of water purification using the FPM with disinfecting properties based on modified cellulose fibers and natural sorbent palygorskite, which can adsorb mechanical impurities, heavy metal ions, entero-viruses, and bacteria.It was found that the samples of modified filtering paper materials with the highest density and lowest thickness and the samples with the lowest density and the highest thickness have higher filtration and sorption capacity compared to samples with the mean values of these technological characteristics.Swelling of cellulose fibers reduces the impact of the compositional structure of the studied FPM samples on their filtering capability and increases the impact of the compositional structure on the sorption ability of these FPM.It was established that the samples with the introduction of about 40 % phosphoric ester of cellulose into their composition have the best technological characteristics.The character of dependence of the rate of filtration process on consumption of purified water, thickness, density and composition of FPM was established. The obtained mathematical models are presented by second-order polynomial and make it possible to take into consideration not only technical specifications, but also the impact of the FPM composition on the rate of filtration process of purified water. Among the studied parameters, the content of sulfate viscose or sulfate bleached viscose in paper-forming mass of the studied samples and consumption of the purified water have the highest impact on the rate of the filtration process at constant pressure and contamination concentration. The proposed mathematical models also allow to determine the necessary compositional structure for obtaining FPM with determined properties, Для очистки води широкого застосування знайшли матеріали паперові фільтрувальні (МПФ), які легко піддаються утилізації. Основним недоліком абсолютної більшості фільтрувальних матеріалів, в тому числі і паперових, є їх схильність до біообростання. Даний недолік суттєво обмежує чи інколи навіть унеможливлює використання фільтрувальних матеріалів та/чи сорбентів у певній сфері. У зв’язку з вищевикладеним, об’єктом даного дослідження став процес очистки води з використанням МПФ із знезаражуючими властивостями на основі модифікованих целюлозних волокон та природного сорбенту палигорскіт, якi можуть сорбувати механічні домішки, іони важких металів, ентеровiруси та бактерії.Встановлено, що зразки модифікованих матеріалів паперових фільтрувальних із найвищою щільністю та найменшою товщиною та зразки із найменшою щільністю та найбільшою товщиною мають більшу фільтраційну та сорбційну здатності у порівнянні із зразками з середніми значеннями цих технологічних параметрів.Набухання целюлозних волокон зменшує силу впливу композиційного складу досліджених зразків МПФ на їх фільтраційну здатність та збільшує силу впливу композиційного складу на сорбційну здатність цих МПФ.Встановлено, що найкращі технологічні характеристики мають зразки, до складу яких було введено близько 40 % фосфорного ефіру целюлози.Встановлено характер залежності швидкості процесу фільтрування від витрати очищуваної води, товщини, щільності та композиційного складу МПФ. Отримані математичні моделі представлені поліномом другого порядку та дозволяють враховувати не тільки технічні характеристики, але і вплив композиційного складу МПФ на швидкість процесу фільтрування очищуваної води. З досліджених параметрів найбільші сили впливу на швидкість процесу фільтрування при сталих тиску та концентрації забруднення мають відсотковий вміст сульфітної віскозної чи сульфатної біленої целюлози у папероутворюючій масі досліджених зразків та витрати очищуваної води. Запропоновані математичні моделі дозволяють також визначити необхідний композиційний склад для отримання МПФ з заданими властивостями, Для очистки воды широкое применение нашли материалы бумажные фильтровальные (МБФ), которые легко поддаются утилизации. Основным недостатком абсолютного большинства фильтровальных материалов, в том числе и бумажных, является их склонность к биообрастанию. Данный недостаток существенно ограничивает или иногда даже делает невозможным использование фильтровальных материалов и / или сорбентов в определенной сфере. В связи с вышеизложенным, объектом нашего исследования стал процесс очистки воды с использованием МБФ с обеззараживающими свойствами на основе модифицированных целлюлозных волокон и природного сорбента палыгорскит, которые могут сорбировать механические примеси, ионы тяжелых металлов, энтеровирусы и бактерии.Установлено, что образцы модифицированных материалов бумажных фильтровальных с наибольшей плотностью и наименьшей толщиной и образцы с наименьшей плотностью и наибольшей толщиной имеют большую фильтрационную и сорбционной способности по сравнению с образцами со средними значениями этих технологических характеристик.Набухание целлюлозных волокон уменьшает силу воздействия композиционного состава исследованных образцов МБФ на их фильтровальную способность и увеличивает силу воздействия композиционного состава на сорбционную способность этих МБФ.Установлено, что лучшие технологические характеристики имеют образцы в состав которых было введено около 40 % фосфорного эфира целлюлозы.Установлен характер зависимости скорости процесса фильтрации от расхода очищаемой воды, толщины, плотности и композиционного состава МПФ. Полученные математические модели представлены полиномом второго порядка и позволяют учитывать не только технические характеристики, но и влияние композиционного состава МПФ на скорость процесса фильтрации очищаемой воды. Из исследованных параметров наибольшие силы влияния на скорость процесса фильтрации при постоянных давлении и концентрации загрязнения имеют содержание сульфитной вискозной или сульфатной беленой целлюлозы в бумагообразующей массе исследованных образцов и расходы очищаемой воды. Предложенные математические модели позволяют также определить необходимый композиционный состав для получения МПФ с заданными свойствами

International audience; It has recently been suggested that pro-tumorigenic host-mediated processes induced in response to chemotherapy counteract the anti-tumor activity of therapy, and thereby decrease net therapeutic outcome. Here we use experimental data to formulate a mathematical model describing the host response to different doses of paclitaxel (PTX) chemotherapy as well as the duration of the response. Three previously described host-mediated effects are used as readouts for the host response to therapy. These include the levels of circulating endothelial progenitor cells in peripheral blood and the effect of plasma derived from PTX-treated mice on migratory and invasive properties of tumor cells in vitro. A first set of mathematical models, based on basic principles of pharmacokinetics/pharmacodynamics, did not appropriately describe the dose-dependence and duration of the host response regarding the effects on invasion. We therefore provide an alternative mathematical model with a dose-dependent threshold, instead of a concentration-dependent one, that describes better the data. This model is integrated into a global model defining all three host-mediated effects. It not only precisely describes the data, but also correctly predicts host-mediated effects at different doses as well as the duration of the host response. This mathematical model may serve as a tool to predict the host response to chemotherapy in cancer patients, and therefore may be used to design chemotherapy regimens with improved therapeutic outcome by minimizing host mediated effects.

‘Babassu’ mesocarp flour has been used by the pharmaceutical, human food and animal feed industries. However, there is lack of standardization in the production, as well as absence of information on the management of the product’s quality. Thus, the objective of this study was to dry the ‘babassu’ mesocarp in forced-air oven and solar dryer, adjust different mathematical models to the experimental data, as well as to quantify the levels of proteins and crude fiber of the produced flour. The criteria for the adjustment were the coefficient of determination, magnitude of the mean relative error, standard deviation of estimate and the residual distribution trend. Drying in the shortest time occurred in oven at 60 °C (370 min), leading to water content of 4.62%, while in the solar dryer the final water content was 8.07% in 6 days. The mathematical model Two Terms showed the best fit to the experimental data for oven drying and the Midilli model showed the best fit in solar dryer. There was an increase in protein content with the drying in solar dryer and oven at 40, 50 and 60 °C (1.36, 1.33, 1.15 and 1.37%, respectively) in relation to fresh mesocarp (0.88%). Drying in both oven and solar dryer promoted increase of protein in the flour. RESUMO A farinha do mesocarpo do babaçu tem sido utilizada pelas indústrias farmacêuticas e de alimentação humana e animal. Contudo, há falta de padronização na produção, bem como ausência de informações do manejo sobre a qualidade do produto. Deste modo, objetivou-se, no trabalho, secar o mesocarpo do babaçu em estufa de ventilação forçada de ar e secador solar, ajustar diferentes modelos matemáticos, bem como quantificar os teores de proteínas e fibras brutas da farinha produzida. Foram usados, como critério do ajuste, o coeficiente de determinação, a magnitude do erro médio relativo, o desvio-padrão da estimativa e a tendência de distribuição dos resíduos. A secagem em menor tempo ocorreu em estufa a 60 ºC (370 min) obtendo-se teor de água de 4,62%, enquanto no secador solar foi em 6 dias com teor de água final de 8,07%. O modelo Dois Termos foi o que melhor se ajustou aos dados experimentais para secagem em estufa e o modelo Midilli em secador solar. Houve um aumento do teor de proteína com a secagem em secador solar e estufa a 40, 50 e 60 ºC (1,36; 1,33; 1,15 e 1,37%, respectivamente) em relação ao mesocarpo in natura (0,88%). A secagem em estufa e em secador solar proporcionou incremento de proteína na farinha.

[EN] In this work, the fouling mechanisms that dominate the ultrafiltration of residual brines from table olive packing plant wastewaters were investigated. For that purpose, Hermia's models adapted to crossflow filtration, resistance-in-series model and a model combining intermediate blocking and cake formation mechanisms were fitted to the experimental data. Tests were performed with a 5 kDa polyethersulfone membrane at transmembrane pressures between 1 and 3 bar and crossflow velocities between 2.2 and 3.7 m s(-1). Results demonstrated that the resistance-in-series model was the most accurate to predict permeate flux evolution with time. The predominant fouling mechanism was cake formation followed by intermediate blocking/adsorption. The fouling resistances that were determined by means of the resistance in series model were tested using a well-established mathematical model proposed by Mondal and De that also combines both fouling phenomena (intermediate pore blocking and cake formation). Results demonstrated that the predicted resistances are consistent with those determined by Mondal and De's model. (C) 2016 Elsevier Ltd. All rights reserved., The authors of this work wish to gratefully acknowledge the financial support of CDTI (Centre for Industrial Technological Development) depending on the Spanish Ministry of Science and Innovation (INNPRONTA program, ITP-20111020).

We present a model to optimise a vaccination campaign aiming to prevent or to curb a Zika virus outbreak. We show that the optimum vaccination strategy to reduce the number of cases by a mass vaccination campaign should start when the Aedes mosquitoes' density reaches the threshold of 1.5 mosquitoes per humans, the moment the reproduction number crosses one. The maximum time it is advisable to wait for the introduction of a vaccination campaign is when the first ZIKV case is identified, although this would not be as effective to minimise the number of infections as when the mosquitoes' density crosses the critical threshold. This suboptimum strategy, however, would still curb the outbreak. In both cases, the catch up strategy should aim to vaccinate at least 25% of the target population during a concentrated effort of 1 month immediately after identifying the threshold. This is the time taken to accumulate the herd immunity threshold of 56.5%. These calculations were done based on theoretical assumptions that vaccine implementation would be feasible within a very short time frame.

This short paper focuses on the role of mathematical models to analyze the impact of pandemics on health resources and the different trade-offs that may be included in them. There is a large body of literature suggesting that mathematical modeling may be helpful to estimate how much additional equipment and infrastructure are necessary to mitigate an increase in demand for health services during a large-scale outbreak of an infectious disease. I comment on the crucial role of these models with a special focus on their strengths and limitations.Este breve documento se centra en el papel de los modelos matemáticos para analizar el impacto de las pandemias en los recursos de salud y las diferentes trade-off que pueden estar presente. Existe una gran cantidad de literatura que sugiere que los modelos matemáticos pueden ser útiles para estimar cuánto equipo e infraestructura adicionales pueden ser necesarios para mitigar un aumento en la demanda de servicios de salud durante un brote a gran escala de una enfermedad infecciosa. Comento sobre el papel crucial de estos modelos con un enfoque especial en sus fortalezas y limitaciones.

The objective of this study was to develop formulations of myrtle pulp with emulsifier/stabilizer (Emustab® and Super Liga Neutra®) in different proportions; characterize the best foam, based on density and over-run; and determine drying kinetics at temperatures of 50, 60, 70, 80 and 90 oC and thicknesses of 0.5, 1.0 and 1.5 cm. Incorporation of 1.5% Emustab® and 0.5% Super Liga Neutra® to the myrtle pulp (F1) proved to be effective for foam-mat drying. The addition of additives influenced the physicochemical parameters of the whole myrtle pulp. The Midilli et al. model showed the best fit to the experimental data.

Cell biology is increasingly evolving to become a more formal and quantitative science. The field of intracellular transport is no exception. However, it is extremely challenging to formulate mathematical and computational models for processes that involve dynamic structures that continuously change their shape, position and composition, leading to information transfer and functional outcomes. The two major strategies employed to represent intracellular trafficking are based on ?ordinary differential equations? and ?agent-? based modeling. Both approaches have advantages and drawbacks. Combinations of both modeling strategies have promising characteristics to generate meaningful simulations for intracellular transport and allow the formulation of new hypotheses and provide new insights. In the near future, cell biologists will encounter and hopefully overcome the challenge of translating descriptive cartoon representations of biological systems into mathematical network models. Fil: Mayorga, Luis Segundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; Argentina Fil: Verma, Meghna. Biocomplexity Institute; Estados Unidos Fil: Hontecillas, Raquel. Biocomplexity Institute; Estados Unidos Fil: Hoops, Stefan. Biocomplexity Institute; Estados Unidos Fil: Bassaganya-Riera, Josep. Biocomplexity Institute; Estados Unidos

In this paper, the issues related to short-circuit calculations in hybrid AC/DC microgrids are discussed. The reference standard for short-current calculations in DC systems is the IEC 61660, which provides a mathematical formulation of the problem. The standard only includes radial DC grids and does not consider a more complex system, such as meshed DC systems or a hybrid AC/DC microgrid. This paper proposes a generalized approach that can be used independently of the characteristics of the hybrid system. The proposed approach is applied to four test microgrids with different distributed sources and number of nodes and the results are compared with those obtained simulating the same grids with Neplan 360®.

Battery energy storage systems (BESS) have been extensively investigated to improve the efficiency, economy, and stability of modern power systems and electric vehicles (EVs). However, it is still challenging to widely deploy BESS in commercial and industrial applications due to the concerns of battery aging. This paper proposes an integrated battery life loss modeling and anti-aging energy management (IBLEM) method for improving the total economy of BESS in EVs. The quantification of BESS aging cost is realized by a multifactorial battery life loss quantification model established by capturing aging characteristics from cell acceleration aging tests.Meanwhile, a charging event analysis method is proposed to deploy the built life loss model in vehicle BESS management. Two BESS active anti-aging vehicle energy management models: vehicle to grid (V2G) scheduling and plug-in hybrid electric vehicle (PHEV) power distribution, are further designed, where the battery life loss quantification model is used to generate the aging cost feedback signals. The performance of the developed method is validated on a V2G peak-shaving simulation system and a hybrid electric vehicle. The work in this paper presents a practical solution to quantify and mitigate battery aging costs by optimizing energy management strategies and thus can further promote transportation electrification.

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works This paper proposes a comprehensive analysis of the Modular Multilevel Converter (MMC) focusing on the different arm applied voltage components, that this paper will refer as degrees of freedom (DOFs), which must be considered in order to perform the internal energy balancing of the converter. The analysis relies on the commonly used differential and additive reference frames. By means of a steady-state analysis, the different voltages components applied and currents components flowing through the converter are studied and an in-depth discussion of the roles of each DOF in the converter is presented. Furthermore, the mathematical expressions of the power exchanged between the AC/DC networks and within the converter, between the arms (vertical) and among phase-legs (horizontal), are derived considering all the DOFs of the MMC, revealing potential interactions among the differential and additive quantities. Finally, the theoretical analysis is validated through comparisons between the values obtained with the mathematical expressions and the simulation results assuming different case scenarios.

In this two-part paper we develop a unifying framework for the analysis of the feasibility of the power flow equations for DC power grids with constant-power loads. In Part I of this paper we present a detailed introduction to the problem of power flow feasibility of such power grids, and the associated problem of selecting a desirable operating point which satisfies the power flow equations. We introduce and identify all long-term voltage semi-stable operating points, and show that there exists a one-to-one correspondence between such operating points and the constant power demands for which the power flow equations are feasible. Such operating points can be found by solving an initial value problem, and a parametrization of these operating points is obtained. In addition, we give a full characterization of the set of all feasible power demands, and give a novel proof for the convexity of this set.

In this work, three ultrafiltration (UF) membranes with different molecular weight cut-offs (MWCOs) and made of different materials were fouled with several whey model solutions that consisted of bovine serum albumin (BSA) (1% w/w), BSA (1% w/w) and CaCl2 (0.06% w/w in calcium) and whey protein concentrate (WPC) with a total protein content of 45% w/w at three different concentrations (22.2, 33.3 and 44.4 g·L− 1). The influence of MWCO and membrane material on the fouling mechanism dominating the UF process was investigated. Experiments were performed using two flat-sheet organic membranes and a ceramic monotubular membrane whose MWCOs were 5, 30 and 15 kDa, respectively. Hermia's models adapted to crossflow UF, a combined model based on complete blocking and cake formation equations and a resistance-in-series model were fitted to permeate flux decline curves. The results demonstrated that permeate flux decline was accurately predicted by all the models studied. However, the models that fitted the best to permeate flux decline experimental data were the combined model and the resistance-in-series model. Therefore, complete blocking and cake formation were the predominant mechanisms for all the membranes and feed solutions tested., The authors of this work wish to gratefully acknowledge the financial support of the Spanish Ministry of Science and Innovation through the project CTM2010-20186.

This paper presents a high-fidelity electro-thermal model of a half-bridge that consists of IGBTs and anti-parallel diodes. The model calculates and estimates the half-bridge voltages, currents, switching and conduction losses considering the operating temperature and current conditions. Moreover, this model is suitable for varying switching frequency operation. The electro-thermal model can be used as an evaluation tool to analyze the performance of control strategies for traction inverter from efficiency, temperature and component stress point of view. In this paper performance of Direct Torque Model Predictive Control (DTMPC) of an Interior Permanent Magnet Synchronous Motor (IPMSM) is evaluated in comparison with Indirect Field Oriented Control (IFOC) with sinusoidal pulse width modulation (PWM). The inverter model and the MPC are both implemented in C-Mex for rapid execution. The MPC algorithm implemented in this research tracks torque reference while using Maximum-Torque-Per-Ampere (MTPA) strategy and minimizing switching losses. Both control systems are able to follow the speed reference. The MPC shows a decrease in losses compared to IFOC when tested with low-speed and high-speed parts of the WLTC profile.

The most commonly used model of solar cells is the single-diode model, with five unknown parameters. First, this paper proposes three variants of the single-diode model, which imply the voltage dependence of the series resistance, parallel resistance, and both resistors. Second, analytical relationships between the current and the voltage expressed were derived using the Lambert W function for each proposed model. Third, the paper presents a hybrid algorithm, Chaotic Snake Optimization (Chaotic SO), combining chaotic sequences with the snake optimization algorithm. The application of the proposed models and algorithm was justified on two well-known solar photovoltaic (PV) cells—RTC France solar cell and Photowatt-PWP201 module. The results showed that the root-mean-square-error (RMSE) values calculated by applying the proposed equivalent circuit with voltage dependence of both resistors are reduced by 20% for the RTC France solar cell and 40% for the Photowatt-PWP201 module compared to the standard single-diode equivalent circuit. Finally, an experimental investigation was conducted into the applicability of the proposed models to a solar laboratory module, and the results obtained proved the relevance and effectiveness of the proposed models.

Model predictive control (MPC) based on long prediction horizons can address the inherent non-minimum phase (NMP) behavior issue of DC/DC boost converters. However, the response time of the controller will increase since the long prediction horizons result in a high computational burden. To solve this problem, a non-minimum phase behavior improving (NPI) MPC with a single prediction horizon is proposed in this paper. Firstly, the actual cause behind the NMP behavior is analyzed. Afterward, the difference equation is modifiedaccording to the analysis and then used in the NPI-MPC. In addition, a fixed switching frequency is generated based on the value of the duty cycle, which is realized in the NPI-MPC algorithm and a modulation. Moreover, a weighting factors design guideline based on the stability criterion of a Jacobian matrix is provided. It effectively reflects the impact and sensitivity of different weighting factors on stability. Finally, we conclude this paper by validating the proposed NPI-MPC method and the weighting factors-design guidelines with the results obtained under experimental conditions.

This paper presents a quantitative dynamic model that can assess the response of a set of users to different Demand-Side Management strategies that are available. The main objective is to conceptualize, implement, and validate said model. As a result of a literature review, the model includes classical demand response techniques and proposes new customer actions and other novel aspects, such as energy culture and energy education. Based on the conceptualization of the model, this paper presents the structure that interrelates customer actions, demand proposals, cost-benefit analysis, and customer response. It also details the main aspects of the mathematical model, which was implemented in the Modelica modeling language. This paper includes simulations of intra-day and inter-day load shifting strategies using real data from the electricity sector in Colombia and different tariff factors. Finally, the results obtained show changes in daily consumption profiles, energy cost, system power peak, and load duration curve. Three conclusions are drawn: (i) Energy culture and pedagogy are essential to accelerate customer response time. (ii) The amount of the bill paid by customers decreases more quickly in the intra-day strategy than in its inter-day counterpart; in both cases, the cost reduction percentage is similar. (iii) Tariff increases accelerate customer response, and this relationship varies according to the Demand-Side Management strategies that are available. Resumen El objetivo principal de este artículo fue conceptualizar, implementar y validar un modelo cuantitativo dinámico que permitiera encontrar la respuesta de un grupo de usuarios ante diferentes estrategias de gestión de la demanda de energía que les son ofertadas. Como resultado de una revisión bibliográfica, se conceptualizó un modelo que incluye técnicas clásicas de respuesta de la demanda, propone nuevas acciones del cliente y otros aspectos novedosos como la cultura y la pedagogía energética. Se determinó la estructura general que interrelaciona las acciones del cliente, las propuestas a la demanda, el análisis beneficio-costo y la respuesta del cliente. Se establecieron modelos matemáticos y se implementaron en lenguaje Modelica. Se realizaron simulaciones para las estrategias de desplazamiento intra-diario e inter-diario, utilizando valores reales del sector eléctrico colombiano y diferentes factores de tarifas. Finalmente, se presentan las gráficas obtenidas para cambios en los perfiles diarios de consumo, costo de la energía, variación del pico de potencia del sistema, cambios en la curva de duración de carga. Las principales conclusiones obtenidas son: (i) La cultura y la pedagogía energética son elementos esenciales para acelerar el tiempo de respuesta del cliente, (ii) El valor de la factura pagada por el cliente se reduce más rápidamente en la estrategia intra-diaria que en la inter-diaria; en ambos casos las reducciones porcentuales en el costo son similares. (iii) El aumento del factor tarifa acelera la respuesta del cliente, esta relación varía según el programa ofrecido.

Large-scale electric aircraft is a disruptive technology to address the environmental impact of air travel. Fault current limitation is crucial to realise the safety and reliability of the electric aircraft, in particular for large-scale electric aircraft using DC distribution network. This paper investigates the behavior of the resistive SFCL under different cryogenic cooling systems including liquid nitrogen and helium gas circulation cooling systems for the electric aircraft DC distribution network. Electromagnetic and thermoelectric models were used to predict the characteristics of resistive SFCL. The simulation results demonstrate that it is promising to design resistive SFCL using liquid nitrogen cooling as well as helium gas circulation cooling systems, which offer flexibility for SFCL cryogenic cooling system for electric aircraft applications.

In this paper, we propose some sufficient conditions for checking the asymptotic stability of switched nonlinear differential-algebraic equations (DAEs) under arbitrary switching signal. We assume that each model of a given switched DAE is externally equivalent to a nonlinear Weierstrass form. With the help of this form, we can define nonlinear consistency projectors and jump-flow solutions for switched nonlinear DAEs. Then we use a different approach from the paper [12] to study the stability of switched DAEs via a novel notion called the jump-flow explicitation, which attaches a nonlinear control system to a given nonlinear DAE and can be used to simplify the common Lyapunov function conditions for both the flow and the jump dynamics of switched nonlinear DAEs. At last, a numerical example is given to illustrate how to check the stability of a switched nonlinear DAE by constructing a common Lyapunov function.

Numerical simulations offer a wide range of benefits. Therefore, they are widely used in research and development. One of the biggest benefits is the possibility of automated parameter variation. This allows testing different scenarios very quickly. Nevertheless, physical experiments in the laboratory or on a test rig are still, and will remain, necessary. Physical experiments offer benefits, e.g., for very complex and/or nonlinear systems and are required for the validation of numerical models. To enhance the quality of experimental NVH investigations and to make use of the benefits of numerical simulation during experimental investigations at the same time, numerical models can be integrated into physical test rigs using the mechanical hardware-in-the-loop (mHIL) method (also referred to as real-time dynamic substructuring, hybrid testing or active control of impedance). During experimental NVH testing, the device under test (DUT) is connected to a mHIL interface which in turn actively emulates the structural dynamics of the boundary condition based on a numerical target impedance model. The goal is to have realistic contact forces instead of blocked forces at the mounting points of the DUT. This paper illustrates the development and characterization of a modular mHIL interface with high bandwidth for NVH testing of a vehicle’s front axle. The physical emulation of structural dynamics based on a target impedance model is demonstrated for synthetic test cases (e.g., emulation of different stiffness settings, or multi-resonant behavior) up to 1 kHz. Furthermore, emulation of the vehicle chassis’ structural dynamics in a single spatial direction is shown for an NVH investigation on a single-axis chassis dynamometer.

Biotechnologiniai pramoniniai procesai siekia išgauti kiek įmanoma daugiau kokybiškesnio tikslinio produkto. Tačiau šiuo metu nėra techninių priemonių, leidžiančių tiesiogiai įvertinti produkto koncentraciją ląstelių kultivavimo proceso metu. Problemai spręsti naudojami programiniai jutikliai, paremti matematiniais modeliais, kurie naudoja informaciją iš realiu laiku matuojamų proceso biotechnologinių parametrų ir būsenos kintamųjų. Darbe aprašyti ir realizuoti skirtingų struktūrų matematiniai modeliai, skirti įvertinti E. Coli ląstelių kultūrų sintezuojamo rekombinantinio baltymo koncentraciją periodinių su pamaitinimu kultivavimo procesų metu. Darbe realizuoti literatūros šaltiniuose pateikti mechanistiniai modeliai, taip pat sudaryti empiriniai („juodosios dėžės“) ir hibdriniai modeliai. Pateiktos modelių parametrų indentifikavimo procedūros mechanistiniams modeliams ir mokymo algoritmai dirbtiniu neuroniniu tinklu grįstiems empiriniams ir hibridiniams modeliams. Modeliai ištirti naudojant realius eksperimentinius duomenis, tyrimų rezultatai palyginti remiantis pasirinktais tikslumo kriterijais., Biotechnological industrial processes aim to produce as much high-quality desired (target) product as possible. However, it is impossible to directly assess target product concentration during cell cultivations. To solve this problem, engineers use software sensors that employ mathematical models which use information from physical measurements and state variables captured during the process. The paper describes and implements mathematical models with different structures to estimate the concentration of the target protein during fed-batch cultivations of E. Coli cell cultures. Mechanistic models described in the literature are implemented, together with developed empirical and hybrid models. Paper presents the procedure for identifying model parameters for mechanistic models and training algorithms for empirical and hybrid models based on artificial neural networks. The models are tested with experimental data and their results are compared according to selected criteria.

Site specific propagation models for highly dynamic vehicle-to-vehicle scenarios become time consuming as the identification of visible surfaces must be performed independently for each transmitter location. Moreover the validation of higher order of ray interactions presents a significant computational overhead. This paper presents an efficient ray-tracing algorithm for vehicle-to-vehicle propagation prediction. The model presented in this paper extends a previous model that uses a pre-computed database of intra-visibility of walls and edges in the environment. The model computes the list of faces and edges that are directly visible to the mobile receiver. This visibility information is then used to reduce the image-tree thereby accelerating the ray validation. The paper also presents an efficient technique to compute diffuse scattered rays in a timely manner. The validation results show considerable time saving over previous models.

The present paper is concerned with the study of the quality of life index. Such an index has become an important index for measuring the well-being of individuals. However, the quality of life index is always a subjective, intangible, and often hard to quantify with precision due to the lack of quantitative models dealing with. The main goal of the present paper is thus to propose a mathematical, quantitative model for the measurement of a quality of life index. The main novelty is firstly the construction of a wavelet dynamic multiscale model to quantify and investigate the effect of time scale on the quality of life index measuring. The proposed procedure is acted empirically on a sample corresponding to Saudi Arabia as a case of study during the period from 2003 to 2020 as part of the 2030-vision plan. Saudi Arabia has implemented the so-called 2030-vision plan where the quality of life improvement is one of the main goals to be attempted. The findings show that wavelets are capable to localize the time-wise behavior of the index contrarily to classical studies which estimate a global view of the index. Moreover, the study shows the link between the quality of life behavior and many other indices.

The Refined Instrumental Variable method for discrete-time systems (RIV) and its variant for continuous-time systems (RIVC) are popular methods for the identification of linear systems in open-loop. The continuous-time equivalent of the transfer function estimate given by the RIV method is commonly used as an initialization point for the RIVC estimator. In this paper, we prove that these estimators share the same converging points for finite sample size when the continuous-time model has relative degree zero or one. This relation does not hold for higher relative degrees. Then, we propose a modification of the RIV method whose continuous-time equivalent is equal to the RIVC estimator for any non-negative relative degree. The implications of the theoretical results are illustrated via a simulation example.

This paper introduces a model for nonlinear dynamics of a resonant micro-mirror designed for large-angle circular scanning. The mirror is driven by aluminum nitride thin-films within a chip-scale vacuum package, which permits large scan angles to be achieved at low voltages, but with substantial nonlinearity in the mirror’s dynamic response. A nonlinear mirror model is proposed and analyzed to identify major trends in mirror performance and implications for mirror design. Analysis focuses on coupling between two axes, which has not been closely examined for multi-axis micro-mirrors. Coupling between axes is found to be capable of augmenting scan amplitude or causing mirror response to collapse from a circular scan patter to an ellipse or line scan, depending on relative strength of model parameters. Good agreement is achieved between modeled and experimental micro-mirror response, with scan amplitudes near $\pm$ 13 degrees under 1.5 V excitation.2022-0181

Free Energy Principle underlies a unifying framework that integrates theories of origins of life, cognition, and action. Recently, FEP has been developed into a Markovian monist perspective (Friston et al. in BC 102: 227-260, 2020). The paper expresses scepticism about the validity of arguments for Markovian monism. The critique is based on the assumption that Markovian models are scientific models, and while we may defend ontological theories about the nature of scientific models, we could not read off metaphysical theses about the nature of target systems (self-organising conscious systems, in the present context) from our theories of nature of scientific models (Markov blankets). The paper draws attention to different ways of understanding Markovian models, as material entities, fictional entities, and mathematical structures. I argue that none of these interpretations contributes to the defence of a metaphysical stance (either in terms of neutral monism or reductive physicalism). This is because scientific representation is a sophisticated process, and properties of Markovian models-such as the property of being neither physical nor mental-could not be projected onto their targets to determine the ontological properties of targets easily.

This paper studies the trending behavior of the COVID-19 dynamics in Israeli cities. The model employed is used to describe, for each city, the accumulated number of cases, the number of cases per day, and the predicted final number of cases. The innovative analysis adopted here is based on the daily evolution of the predicted final number of infections, estimated with data available until a given date. The results discussed here are illustrative for six cities in Israel, including Jerusalem and Tel Aviv. They show that the model employed fits well with the observed data and is able to suitably describe the COVID-19 dynamics in a country strongly impacted by the disease that holds one of the most successful vaccination programs in the world.

Publisher Copyright: Author A discrete winding function analysis (DWFA) based approach for the modelling of skewed rotor cage-type induction motor with minimal simulation time is presented in this paper. The rotor slot skew has a significant attenuating impact on principal slotting harmonics (PSH) or rotor slotting harmonics (RSH). These harmonics can play a significant role in sensor-less speed estimation and condition monitoring of induction machines. The advanced fault diagnostic algorithms are becoming increasingly dependent on the fast and accurate mathematical models of electrical machines. The most accurate models are based on the finite element method (FEM), but the computational complexity and the required simulation time make them unsuitable for model-dependent fault diagnostic algorithms. Moreover, as most models are 2D, they cannot incorporate axial asymmetries such as rotor slot skews. Furthermore, most analytical models, such as modified winding function analysis (MWFA), depend upon the continuous integration functions, increasing complexity while implementing them in the online environment in digital signal processing boards. To resolve all those issues, DWFA based model is proposed in this paper, which can simulate the majority of the faults in negligible time compared to the corresponding FEM models. The impact of slot skews and unbalanced power supply on the current spatial harmonics is studied, and the results are compared with the practical measurements taken from the laboratory setup.

На основе расчетов процессов самовоспламенения водородно-воздушных смесей в гомогенных химических реакторах с привлечением уравнений детального кинетического механизма разработано новое уравнение глобальной кинетики (макрокинетики) окисления водорода при высоких давлениях. Выбор детального кинетического механизма, достаточно хорошо описывающего процессы при высоких давлениях, произведен на основе сравнительного анализа значительного количества литературных источников, часть из которых приведены в работе. Сравнение различных детальных кинетических механизмов производилось путем тестирования процессов самовоспламенения водорода в идеализированных гомогенных реакторах постоянного объема и постоянного давления с помощью численного моделирования системы обыкновенных дифференциальных уравнений, описывающих процессы самовоспламенения водорода. Полученное уравнение макрокинетики описывает скорость процессов окисления водорода, которые в альтернативном случае детального кинетического механизма необходимо моделировать с привлечением нескольких десятков дифференциальных уравнений. Новое уравнение макрокинетики водорода предназначено для численного моделирования физико-химических процессов при разработке новых технологий и энергетических устройств., This paper has developed and presented a new equation for the global kinetics (macrokinetics) of hydrogen oxidation at high pressures. It is based on equations for calculations of the self-ignition processes of hydrogen-air mixtures in homogeneous chemical reactors using the equations of the detailed kinetic mechanism. The choice of a detailed kinetic mechanism that describes the processes at high pressures well enough is based on a comparative analysis of a significant number of references, some of which are given in the paper. Various detailed kinetic mechanisms are compared by testing the processes of hydrogen selfignition in idealized homogeneous reactors of constant volume and constant pressure using numerical modeling of a system of ordinary differential equations describing the processes of self-ignition of hydrogen. The resulting macrokinetics equation describes the rate of hydrogen oxidation processes which, in the alternative case of a detailed kinetic mechanism, must be modeled using several dozen differential equations. The new equation of hydrogen macrokinetics is intended for the numerical simulation of physicochemical processes in developing new technologies and energy devices.

Treballs Finals del Màster d'Economia, Facultat d'Economia i Empresa, Universitat de Barcelona. Curs: 2021-2022, Tutor: Josep Maria Izquierdo Aznar; Pedro Calleja Cortes, Greenhouse gas(GHGs) emissions have resulted in global warming which further leads to climate change. To reduce GHGs emissions, governors make attempts to create multilateral agreements among countries. Their failure of establishing sustainable agreements drives researchers to find fair and equitable distribution rules. Based on Emission Egalitarianism for each individual, this paper creatively generates the generalized constraint equal awards rule (GEA), provides corresponding algorithm to compute emission allocations from the GEA rule and points out several characteristics of this rule. To determine a fairer rule, this paper introduces Lorenz dominance and proved in n-agent case that the allocation provided by the GEA rule is Lorenz-undominated by all other allocations from any other rules. Furthermore, in a simplified 2-agent case this paper confirmed the allocations derived from the GEA rule Lorenz dominates all other allocations from any other rules.

Авторами этой статьи ведутся многолетние систематические исследования в области автоматизации проектирования систем газоснабжения ракетно-космических комплексов (СГС РКК). Данная статья носит обзорный характер, она подготовлена по результатам монографии авторов, которая вышла в декабре 2021 года. Основной целью статьи является краткое изложение основных результатов, полученных в этой работе. Основные задачи, которые решены в монографии, следующие. Создано иерархическое по структуре математическое обеспечение с учетом свойств реального газа и распределенности его параметров. На этой основе разработано алгоритмическое и программное обеспечение для решения типовых задач анализа, выполнены численные исследования, подтвердившие адекватность и высокую точность разработанных математических моделей. Затем разработана система автоматизированного проектирования СГС РКК, которая, наряду с программным обеспечением, включает информационное и методическое обеспечение, подсистему документирования результатов. С ее использованием решен ряд важных практических задач.Изложенная в монографии информация представляет интерес для разработчиков газовых систем различного назначения, специалистов по термодинамике и газодинамике, а также по системам автоматизированного проектирования., The authors of this paper are conducting the systematic research in the field of automation of the design of gas supply systems for rocket and space complexes (GSS RSC) many years. This article is of a review nature, it was prepared based on the results of the monograph of the authors, which was published in December 2021. The main purpose of the paper is a summary of the main results obtained in this work. The main tasks which are solved in the monograph are as follows. A hierarchical in structure software has been created, taking into account the properties of a real gas and the distribution of its parameters. Based on it, algorithmic and software for solving typical problems of analysis have been developed, and numerical studies have been carried out that have confirmed the adequacy and high accuracy of the developed mathematical models. Then, a computer-aided design system GSS RSC was developed, which, along with software, includes information and methodological support, a subsystem for results documenting. A number of important practical problems have been solved with its use. The information presented in the monograph is of interest to developers of gas systems for various purposes, specialists in thermodynamics and gas dynamics, as well as in computer-aided design systems., Мониторинг. Наука и технологии, Выпуск 1 (51) 2022

This paper develops a robust chance-constrained model for handling the uncertainties of generation and consumption in multi-carrier energy hubs. The proposed model incorporates corresponding loading factors for each type of electrical, heating, and cooling loads. This is done to assess the maximum loadability of the whole system. In this respect, the chance-constrained approach is implemented for the feasibility assessment of the operation problem with uncertainties. The uncertainties which are assumed here include the forecast errors of electrical, heating, and cooling load demands, and the volatile solar power generation. The overall problem formulation is developed in the mixed-integer linear programming (MILP) framework. The standard chance-constrained approach is converted to a deterministic optimization model by utilizing the Big M method. The main objective of the proposed model is to maximize the loadability index with uncertainties while addressing the permissible risk index of the decision-maker. The studied energy hub comprises electrical, heating, and cooling loads, and the energy flow technique is adopted in this paper to model the load balance equations. The simulation results are presented for different scenarios while addressing features of the proposed model for the summer and winter seasons. Furthermore, the developed model is evaluated for different scenarios and a comparison is made with the information-gap decision theory (IGDT) method.

Publisher Copyright: Author This paper presents the core concepts for the poST language - a process-oriented extension of the IEC 61131-3 Structured Text (ST) language which intends to provide a conceptual consistency of the PLC source code with technological description of the plant operating procedure. The poST can be seamlessly used as a textual programming language for complex PLC software in the context of IEC 61131-3 (3rd Edition). The language combines the advantages of FSM-based programming with the conventional syntax of the ST language which would facilitate its adoption. The poST language assumes that a poST-program is a set of weakly connected concurrent processes, structurally and functionally corresponding to the technological description of the plant. Each process is specified by a sequential set of states. The states are specified by a set of the ST constructs, extended by TIMEOUT operation, SET STATE operation, and START / STOP / check state operations to communicate with other processes. The paper describes the basic syntax of the poST language, demonstrates the usage of the poST language by developing control software for an elevator, and compares the development in poST with pure Structured Text.

The increasing penetration of renewables in power systems reconfigures the generation mix and geography distribution, resulting in more frequent power flow congestion. Conventionally, a relatively conservative dispatch margin for transmission congestion in network constraints was reserved to ensure safe operation due to potential deviations introduced by DC power flow modeling and conservative line rating. This paper proposes a real-time power market clearing model with improved network constraints considering power transfer distribution factor (PTDF) correction and fast-calculated dynamic line rating. The clearing model based on PTDF correction is proposed first employing the Taylor expansion with the voltage and phase angle approximation. An improved dynamic line rating model is further applied into the clearing model based on the piecewise linear approximation method, which calculates real-time conductor temperature faster with sufficient precision. We test and verify the validity of the proposed model based on three independent systems including the IEEE 39-bus system, the IEEE 2383-bus system, and the real power grid system in Yunnan province of China, respectively. The results show that the improved clearing model reduces the calculated power flow deviation between the clearing results and real conditions compared with traditional security constraints, where the efficiency of power grid operation is also increased.

© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works This paper proposes an optimization-based size reduction methodology for Modular Multilevel Converters (MMC), focusing on minimizing the converter's sub-module capacitor CSM. The analysis is performed considering both the converter's current and voltage limitations and the Transmission System Operator (TSO) Fault Ride Through (FRT) requirements. By means of a steady-state analysis, the time-domain expressions of the converter's arms energies are obtained and their behavior throughout the MMC's operating range is shown. Based on these expressions, the optimization-based problem to reduce the CSM size is developed and its constraints are imposed to ensure that the converter's voltage and current levels are within its design limitations. The suggested method is compared with different approaches for distinct active and reactive power set-points, where it is shown that the SM capacitor size can be reduced up to 24% in comparison with the method with worst performance and up to 7% regarding the best method used for comparison purposes. Furthermore, time-domain simulations of the MMC considering several AC voltage sags are performed in order to demonstrate that the dynamics of the SM capacitor and the arm applied voltages are within acceptable margins during the different operations.

Cyber-physical system security for electric distribution systems is critical. In direct switching attacks, often coordinated, attackers seek to toggle remote-controlled switches in the distribution network. Due to the typically radial operation, certain configurations may lead to outages and/or voltage violations. Existing optimization methods that model the interactions between the attacker and the power system operator (defender) assume knowledge of the attacker's parameters. This reduces their usability. Furthermore, the trend with coordinated cyberattack detection has been the use of centralized mechanisms, correlating data from dispersed security systems. This can be prone to single point failures. In this paper, novel mathematical models are presented for the attacker and the defender. The models do not assume any knowledge of the attacker's parameters by the defender. Instead, a machine learning (ML) technique implemented by a multi-agent system correlates detected attacks in a decentralized manner, predicting the targets of the attacker. Furthermore, agents learn optimal mitigation of the communication level through Q-learning. The learned attacker motive is also used by the defender to determine a new configuration of the distribution network. Simulations of the technique have been performed using the IEEE 123-Node Test Feeder. The simulation results validate the capability and performance of the algorithm. U.S. National Science Foundation [1837359]; Commonwealth Cyber Initiative (CCI), State of Virginia [PR6ZBSTA, 5GPG] Published version This work was supported in part by the U.S. National Science Foundation under Grant 1837359; and in part by the projects under Grant PR6ZBSTA and Grant 5GPG sponsored by Commonwealth Cyber Initiative (CCI), State of Virginia.

BackgroundThis paper intends to check whether and how a hypothetical dengue vaccine could contribute to issue of evolution of bacteria resistance against antibiotics by reducing the number of patients that would inappropriately being treated with antibiotics.MethodsWe use a new mathematical model that combines, in a novel way, two previously published papers, one on the evolution of resistance against antibiotics and one classical Ross-Macdonald model for dengue transmission.ResultsThe model is simulated numerically and reproduces a real case of evolution of resistance against antibiotics. In addition the model shows that the use of a hypothetical dengue vaccine could help to curb the evolution of resistance against an antibiotic inappropriately used in dengue patients. Both the increase in the proportion of resistant bacteria due to the misuse of antibiotics in dengue cases as a function of the fraction of treated patients and the reduction of that proportion as a function of vaccination coverage occur in a highly non-linear fashion.ConclusionThe use of a dengue vaccine is helpful in reducing the rate of evolution of antibiotic resistance in a scenario of misuse of the antibiotics in dengue patients.

Made available in DSpace on 2022-04-28T19:42:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico A meta-analysis was conducted to develop and evaluate new empirical predictive models for drinking water intake (DWI) of growing lambs. A large dataset containing 213 experimental diets from 47 experiments published in 44 peer-reviewed papers was built. Selected explanatory variables were grouped into animal (bodyweight initial (BWi); body weight final (BWf); average daily gain (ADG); feed conversion ratio (FCR); nitrogen intake (Nint), diet composition (dry matter; ash; crude protein (CP); neutral detergent fiber; forage), dry matter intake (DMI) and total digestible nutrient (TDN) and/or total digestible nutrient intake (TDNI) inputs. To develop predictive models, the dataset (peer-reviewed papers) was randomly divided into two subsets for statistical analyses. The first data subset was used to develop equations to predict DWI (27 peer-review papers; 28 experiments; 139 experimental diets), and the second data subset was used to assess the adequacy of the predictive models (17 peer-review papers; 19 experiments; 74 experimental diets). Ash was the main diet input affecting DWI in growing lambs, while FCR affected DWI more than ADG and Nint among the animal inputs. For growing lambs, the use of predictor variables associated with energy requirements improved the accuracy of the models when compared to those which used DMI. Among the developed models, the complete ones, which include diet and animal input, present better predictive quality. The use of the Diet + Animal Ib Model is recommended for the prediction of DWI in growing lambs. Animal Unit of Digestive and Metabolic Studies in the Department of Animal Science School of Agricultural and Veterinarian Sciences São Paulo State University (UNESP) Nucleus of Studies in Agricultural Environment and Animal Welfare in the Department of Agricultural Enginneering Federal University of Ceará (UFC) Animal Unit of Digestive and Metabolic Studies in the Department of Animal Science School of Agricultural and Veterinarian Sciences São Paulo State University (UNESP)

The electrical energy supply of industrial equipment is provided by electrical power stations with high- (HT), medium- (MV) and low-voltage (LV) busbars. Consumers are connected to either MV or LV busbars. In this paper, a real power station was considered, through which the gasoline extraction from the well gas installation is powered. Electric consumers (electric motors) supplied by a MV busbar have active power of 13.54 MW, and those fed by a LV busbar have active power of 6.4 MW. Since electrical consumers operate in explosive environments, the design and operating conditions are more severe than in the case of electrical installations operating in non-explosive environments. The case of a single phase-to-ground fault occurring on the HV transmission lines feeding the power station has been analysed. First, the mathematical models for the calculation of the phase voltages, the dissymmetry and asymmetry coefficients, the reduction coefficient of the plus sequence component, and the effective values of the phase voltages were established. The influence of the source impedance (the equivalent impedance of the HV transmission lines) and of the neutral point configuration of the HV/MV medium-voltage transformer on the calculated quantities was analysed. Then, the results obtained using the established mathematical models were compared with those obtained experimentally by provoking a single-phase-to-ground fault near the HV busbars of the real power station. This study has shown that the de-symmetrisation of the phase voltages of the MV and LV busbars is lower when using the Y/Δ connection for the HV/MV transformer. As a result, it is recommended the Y/Δ connection be used for this transformer, instead of the Y0/Δ connection.

Distribution transformers (DTs) are deemed as fundamental and high-priced equipment of power grids and their failure influences grid reliability. Continuity of DTs operation highly depends on its insulation conditions and following that to the hotspot temperature (HST). In this paper, a novel formula is proposed for HST prediction of DTs by considering the effective electrical and mechanical parameters on heat dissipation capacity. As well as, a complete and accurate 3D modeling based on computational fluid dynamic (CFD) is presented to validate the proposed novel formula for HST prediction. In this modeling, the conservator, which plays a key role in the HST value, is accurately modeled. Optical fiber sensors (OFSs) are utilized in the studied 500 kVA DT to verify the accuracy of the proposed HST prediction formula during the experimental temperature rise test. Experimental results show that the proposed formula is highly accurate and has an acceptable correlation with the empirical values. The root mean square error (RMSE), mean error (ME) and average error percentage (AEP) of the proposed formula are 0.3°C, 0.3°C and 0.37%, respectively, in HST transient values and 0.3°C, 0.3°C and 0.29% in HST steady state values, which substantiate the precision and proficiency of the proposed HST prediction formula rather than IEC and IEEE equations. Finally, a thermal camera is employed to verify the results of CFD-based 3D modeling in top-oil temperature (TOT), bottom-oil temperature (BOT) and conservator oil temperature (COT) during the experimental tests. According to the measurement results, temperatures of CFD-based 3D simulation and thermal camera in the aforementioned three points are in good agreement with each other and AEP is less than 1.4%, which indicates the accuracy and efficiency of the proposed 3D modeling.

Kitting is a common approach of materials supply with mixed-model assembly, by which components are supplied to the assembly process in pre-sorted kits. With kitting, the kit preparation is a labour intensive process and order batching is often applied to enhance efficiency. Here, improved quality and efficiency by means of automation is desirable, but knowledge of the potential of collaborative robots to support kit preparation with order batching is lacking. The purpose of this paper is to identify the potential of cobots to support time-efficient kit preparation with order batching, when the pick task is performed manually and a cobot carries out the sort task. A modelling approach is applied with experimental data from laboratory experiments to compare the cycle time between fully manual and cobot-supported kit preparation with order batching. The findings suggest that a cobot-supported sort task leads to a comparable average cycle time, with less variability of the cycle time, when compared to the fully manual setup. The paper contributes several insights on the application of cobots to support kit preparation, and the model developed in the paper can be used by practitioners to assess the potential of cobots to support their processes for kit preparation. © 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd.

Technology-mediated mathematical modelling has been recognized as a significant learning context. This paper reports on a study aiming to characterize the modelling routes performed by Costa Rican undergraduate students when solving a mathematical modelling task using technological resources as a means to explore the concept of linear transformation. Data collected from audio records of students’ discussions, their written work, and GeoGebra files show that the group of two students we focus in this paper performed a linear modelling route, by creating a mathematical model with the software, which highlights the visual aspect and the geometric transformation concept. UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Matemática

Passive photonic integrated circuits (PICs) can be easily characterized in the frequency-domain, but their accurate time-domain performance evaluation is a hurdle for system-level designers, especially when dealing with resonant circuits having highly dispersive behavior, such as ring resonators. In this paper, a new equivalent circuit modeling and simulation approach is proposed, based on the Complex Vector Fitting algorithm, able to perform accurate and robust time-domain simulations of passive PICs directly in standard SPICE simulators. The proposed modeling technique starts from scattering parameters of passive PICs, and is able to capture linear and high order dispersion, backscattering, and wavelength dependent effects. Considering the different nature of optical and electronic signals, a novel concept of equivalent voltage and current for optical waveguides is proposed to simplify the optical to electronic ports conversion and to make it possible to connect and terminate the equivalent circuit models as needed in SPICE simulators, natively supporting bidirectional signal propagation in a waveguide. This work provides a precise and reliable solution to evaluate time-domain characteristics of passive PICs and to access any internal nodes within a circuit, such as the signals inside a ring resonator. Three examples of time-domain simulations of passive PICs in commercial SPICE simulators are presented to demonstrate the flexibility and advantages of the proposed technique.

Power distribution systems are experiencing a large-scale integration of Converter-Interfaced Distributed Energy Resources (CIDERs). This complicates the analysis and mitigation of harmonics, whose creation and propagation are facilitated by the interactions of converters and their controllers through the grid. In this paper, a method for the calculation of the so-called Harmonic Power-Flow (HPF) in three-phase grids with CIDERs is proposed. The distinguishing feature of this HPF method is the generic and modular representation of the system components. Notably, as opposed to most of the existing approaches, the coupling between harmonics is explicitly considered. The HPF problem is formulated by combining the hybrid nodal equations of the grid with the closed-loop transfer functions of the CIDERs, and solved using the Newton-Raphson method. The grid components are characterized by compound electrical parameters, which allow to represent both transposed or non-transposed lines. The CIDERs are represented by modular linear time-periodic systems, which allows to treat both grid-forming and grid-following control laws. The method's accuracy and computational efficiency are confirmed via time-domain simulations of the CIGR\'E low-voltage benchmark microgrid. This paper is divided in two parts, which focus on the development (Part I) and the validation (Part II) of the proposed method.

This paper introduces a new mathematical model that is used to compute either the interfacial tension of quiescent axisymmetric pendant/sessile drops and pendant/captive bubbles. This model consists of the Young–Laplace equation, that describes interface shape, together with suitable boundary conditions that guarantee a prescribed volume of drops/bubbles and a fixed position in the capillary. In order to solve the problem numerically, the Young–Laplace equation is discretized by using numerical differentiation and the numerical solutions are obtained applying the well-know Newton method. The paper contains a validation of the new methodology presented for what theoretical bubble/drops are used. Finally, some numerical results are presented for both drops and bubbles of water as well as several surfactant solutions to demonstrate the applicability, versatility and reproducibility of the proposed methodology., RSC Advances, 9 (28), ISSN:2046-2069