Variogram investigation of covariance shape within longitudinal data with possible use of a krigeage technique as an interpolation tool: Sheep growth data as an example

peer-reviewedMost quantitative traits considered in livestock evolve over time and several continuous functions have been proposed to model this change. For individual records (longitudinal data), it is evident that measures taken at close dates are generally more related than these further apart in time. Since milk production involves several parities, the covariance structure within this trait has been analysed by time series methodology. However, the covariance structure within traits that are not repeated during life, such as those linked to growth, has not yet been formally modelled by considering time lags as is done in time series analysis. We propose an adaptation of the variogram concept to shape this structure; which gives the possibility of kriging missing data at any particular time. A new parameter, the halftime variogram, has been proposed to characterise the growing potential of a given population. The weight records of a Barbarine male lamb population were used to illustrate the methodology. The variogram covering the whole growth process in this population could be modelled by a logistic equation. To estimate the missing data from birth to 105 days of age, a simple linear interpolation was sufficient since kriging on a linear model basis gives a relatively more accurate estimation than kriging on a logistic model basis. Nevertheless, when both known records around the missing data are distant, a krigeage on the basis of the logistic model provides a more accurate estimation

Multi-Fuel Burner Systems for Industrial Applications

Multi-fuel firing systems are used in several industrial processes such as in power stations, drying mills and metallurgical plants as well as in rotary kiln systems, industrial boilers, cogeneration plants and various thermal process factories. Such systems should being not only able to utilize different fuel types, but also to respond flexible due to changing in fuel compositions and qualities. In particular the ignition, stability and pollutant problems must be taken into account. That means that these systems should fulfill the operational parameters and ecological target according to German Technical Instructions on Air Quality Control TA Luft 2002. The Operation of these so called multi fuels systems is determined on the one hand by the conditions of the start-up procedure (e. g. drying of the refractory material, creation of the necessary operating environment) and on the other hand by the process-related requirements, fluctuating commodity prices, unstable fuel supplies and the use of internally resulting production scrap. In this paper two multi-fuel burner systems are selected from the extensive Brinkman’s production program to be shown in details. These are combined combustion systems for «pulverized coal-gas» and «pulverized coal-oil», respectively.Многотопливные горелочные системы используются в различных промышленных процессах, на ТЭС и в металлургии, включая сухое измельчение сырых материалов, во вращающихся печах, промышленных котлах, установках когенерации и специальных термических технологиях. Соответствующие системы должны быть пригодны для использования различных видов топлива и гибко реагировать на изменения его состава и качества, в частности, необходимо учитывать устойчивость воспламенения топливной смеси и сопутствующее загрязнение окружающей среды. Такие системы должны обеспечивать эксплуатационные параметры и экологические нормативы в соответствии с германскими техническими стандартами качества воздуха (TA Luft 2002 г.). Качество работы этих многотопливных систем определяется, с одной стороны, пусковыми условиями (например, сушка огнеупоров, создание требуемой рабочей среды), с другой стороны, эксплуатационными требованиями, колебаниями цен на сырьевые продукты и готовые товары, а также условиями, учитывающими специфику технологии, нестабильное снабжение топливом. Принимается во внимание также внутренняя утилизация отходов в пределах производства. В статье рассмотрены две многотопливные горелочные системы, выбранные из обширной производственной номенклатуры ООО «Бринкман». Соответственно представлены системы комбинированного сжигания пылеугольного и газового топлива, а также пылеугольного топлива с жидким топливом.Багатопаливні пальникові системи використовуються у різних промислових процесах, на ТЕС та у металургії включно з сухим подрібненням вологих матеріалів у обертових пічах, промислових котлах, установках когенерації та спеціальних термічних технологіях. Відповідні системи мають бути придатними для використання різних видів палива та гнучко реагувати на зміни його складу та якості, зокрема необхідно враховувати стійкість займання паливної суміші та супутнє забруднення довкілля. Такі системи мають забезпечувати експлуатаційні параметри та екологічні нормативи у відповідності до германських технічних стандартів щодо якості повітря (TA Luft 2002 р.). Якість роботи цих багатопаливних систем визначається пусковими умовами (наприклад, сушіння вогнетрив ів, створення потрібного робочого середовища) та, експлуатаційними вимогами, коливаннями цін на сировинні продукти та готові товари, а також умовами, що враховують специфіку технології, нестабільне постачання палива. Приймається до уваги також внутрішня утилізація відходів у межах виробництва. Розглянуто дві багатопаливні пальникові системи, вибрані з великої виробничої номенклатури ТОВ «Брінкман». Представлено системи комбінованого спалювання пиловугільного та газового палива, а також пиловугільного палива з рідким паливом

A low-cost PV Emulator for testing MPPT algorithm

International audienceThe high cost of commercial PV emulators requires finding new solutions for building low-cost system having similar behavior of PV panel. In this work, we present a low-cost emulator using a variable DC supply with a series variable resistor; based the maximum power transfer theorem. On the other hands, a study of the behavior of this emulator is done. The results of experiments test are shown that our PV emulator can provide a simple, efficient and a low-cost way for researchers to test and verify their MPPT algorithms in a laboratory environment

Real-time virtual instrumentation of Arduino and LabVIEW based PV panel characteristics

International audienceThis paper describes a virtual instrument based on a low-cost embedded board to monitor and plot the PV panel characteristics under real operation condition. The system design is based on a low-cost Arduino acquisition board in which the ATMega328 microcontroller is integrated. The acquisition is made through a low-cost current and voltage sensors and the data are transmitted in LabVIEW by using LIFA Interface for Arduino. Hence, the I-V (current-voltage) and P-V (power-voltage) characteristics for PV panel, which processed under actual conditions, can be obtained and plotted directly on a monitoring platform in LabVIEW. The proposed instrument can be used for educational or research purposes using a low-cost and easily hardware without having extensive knowledge about electronic engineering. The present instrumentation technique provides easy access to the collected data for further analysis

Study of a Low-Cost PV Emulator for Testing MPPT Algorithm Under Fast Irradiation and Temperature Change

International audienceThis paper presents a study of a low-cost photovoltaic (PV) emulator to test the real implementation of maximum power point tracking (MPPT) algorithm. This PV emulator is composed of a variable DC supply in series with a variable resistor; it is based on the maximum power transfer theorem in order to provide a curve that exhibits a peak which can be tracked by an MPPT algorithm. Moreover, this emulator can be used to test the performance of the MPPT algorithm under fast variation of the solar irradiance and temperature. For this reason, the P&O MPPT algorithm with a boost DC-DC converter is used in order to validate the functionality of the PV emulator. Finally, the experimental results show that our PV emulator can provide a simple, efficient and low-cost way for users (researchers, engineers, students, etc.) to test and validate their MPPT algorithms

Shape and symmetry in the otolith of two different species Mullus barbatus and Mullus surmuletus (Actinopterygii: Perciformes: Mullidae) in Tunisian waters

Background. In Tunisian waters, there are only two mullet species, the red mullet, Mullus barbatus Linnaeus, 1758, and the striped red mullet, Mullus surmuletus Linnaeus, 1758. They are distributed along the coasts of eastern Atlantic from the North Sea to the northern part of West Africa. Therefore, M. barbatus and M .surmuletus are a valuable component of the commercial fishery in Tunisia. The goal of this study was to investigate the stock structure discrimination and otolith asymmetry for specimens of the mentioned above two species of the family Mullidae from waters of northern Tunisia. Materials and methods. We collected a total of 120 specimens of M. barbatus and M. surmuletus from Lac de Bizerte. The sampling was conducted within three months (March–April–May). The Elliptical Fourier Analysis (EFA) was performed to evaluate the degree of similarity in the otoliths and to determine the asymmetry percentage. Results. The Discriminant Factor Analysis shows significant results that are clearly demonstrated by an asymmetry when comparing otoliths (P < 0.05) within each population and a difference in shape when comparing the same side between the two species: between the two sides (right–right and left–left). Conclusion. The comparison of the otolith morphology of the two species showed a significant difference in shape and a left–right asymmetry of otoliths between and within populations. This result is probably related to genetic and local environmental factors. In fact, this investigation improves the knowledge of the stock discrimination for M. barbatus and M. surmuletus and provides useful information for analyzing fisheries management of these species in Tunisia

Investigation of Partial Shading Scenarios on a Photovoltaic Array’s Characteristics

The purpose of this study is to investigate the impact of different partial shading scenarios on a PV array’s characteristics in order to develop a simple and easy-to-implement GMPP controller that tracks the PV array’s global maximum power point (GMPP). The P-V characteristic of the PV array becomes more complicated under partial shading, owing to the presence of many power peaks, as opposed to uniform irradiance conditions, when there is only one peak called the maximum power point. In fact, and according to an experiment conducted in this study, when a PV array is partially shaded, the P-V characteristic mostly presents two peaks, given the existence of only two levels of irradiance, one of which is called the global peak (i.e., the GMPP). Furthermore, the first peak is located at Vmpp1 (the PV array’s voltage corresponds to this peak), whereas the second is at Vmpp2. The proposed approach works by estimating the values of Vmpp1 and Vmpp2 using two equations in order to control the DC/DC converter of the PV system. The first equation is used when the GMPP is at the first peak, while the other is used when the GMPP is at the second peak. Several scenarios are simulated and presented in this paper to verify the accuracy of these equations. In addition, some conclusions are drawn to suggest a simple method for tracking the GMPP

Investigation of Partial Shading Scenarios on a Photovoltaic Array&rsquo;s Characteristics

The purpose of this study is to investigate the impact of different partial shading scenarios on a PV array&rsquo;s characteristics in order to develop a simple and easy-to-implement GMPP controller that tracks the PV array&rsquo;s global maximum power point (GMPP). The P-V characteristic of the PV array becomes more complicated under partial shading, owing to the presence of many power peaks, as opposed to uniform irradiance conditions, when there is only one peak called the maximum power point. In fact, and according to an experiment conducted in this study, when a PV array is partially shaded, the P-V characteristic mostly presents two peaks, given the existence of only two levels of irradiance, one of which is called the global peak (i.e., the GMPP). Furthermore, the first peak is located at Vmpp1 (the PV array&rsquo;s voltage corresponds to this peak), whereas the second is at Vmpp2. The proposed approach works by estimating the values of Vmpp1 and Vmpp2 using two equations in order to control the DC/DC converter of the PV system. The first equation is used when the GMPP is at the first peak, while the other is used when the GMPP is at the second peak. Several scenarios are simulated and presented in this paper to verify the accuracy of these equations. In addition, some conclusions are drawn to suggest a simple method for tracking the GMPP

Stock discrimination of two insular populations of Diplodus annularis (Actinopterygii: Perciformes: Sparidae) along the coast of Tunisia by analysis of otolith shape

Background. The annular seabream, Diplodus annularis (Linnaeus, 1758), is the most common sparid fish in the Mediterranean Sea. This species is widespread in Tunisia. Despite their economic importance, due to their excellent white and delicate flesh (demersal fish) and their significant size, few studies have hitherto focused on stock discrimination and on the fisheries management. The goal of this research was to evaluate the stock structure of D. annularis for two Tunisian insular populations  based on the otolith shape, using different statistical approaches. Materials and methods. The specimens of Diplodus annularis were collected during five months ranging from May through September 2014 at two sites: Djerba and Kerkennah. In total, 120 fish were collected from the two study sites: 60 specimens of each population (30 males and 30 females) and were included in different statistical analyses. The Fourier coefficients were determined to evaluate the degree of similarity in the otoliths and detect the reciprocal variability. Results. By comparing the two studied populations, we revealed statistical significant differences, an asymmetry (left–right), of otoliths (P < 0.05). In the same population, symmetry (left–right) was detected for the males, females of Kerkennah, and females of Djerba. However, an asymmetry was detected only for the males of Djerba. Also, sexual dimorphism was observed only for the Djerba population. Conclusion. The comparison of the otolith morphology of the two populations showed a clear difference in shape and a left–right asymmetry of otoliths. This asymmetry indicates that the two populations belong to different stock of fish. The stocks characterization is considered as an important tool for fisheries management. Further studies are necessary to determine the origin of the otolith shape differences and whether they are related only to environmental conditions or a genetic basis may also be responsible