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This note clarifies an important approximation used to simulate the breakdown field in the SiO2 liner of a SiC Charge-Sheet Superjunction - a new power device structure - reported by Akshay and Karmalkar (2020). This electric field simulation sought to assure that the new device does not suffer from SiO2 reliability problems. The note answers two questions: (a) Why do we remove the SiO2 liner which is the very region of our interest during device simulation, when a simulator allows inclusion of such a region? (b) How can one solve for the field in a region (SiO2 in the present case) by neglecting that very region during device simulations? Our note reinforces the insight - “Modeling is the art of making approximations”.

[EN] Emerging Industry 4.0 applications require ever-increasing amounts of data and new sources of information to more accurately characterize the different processes of a production line. Industrial Internet of Things (IIoT) technologies, and in particular Wireless Sensor Networks (WSNs), allow a large amount of data to be digitized at a low energy cost, thanks to their easy scalability and the creation of meshed networks to cover larger areas. In industry, data acquisition systems must meet certain reliability and robustness requirements, since other systems such as predictive maintenance or the digital twin, which represents a virtual mapping of the system with which to interact without the need to alter the actual installation, may depend on it. Thanks to the IEEE 802.15.4e standard and the use of Time-Slotted Channel Hopping (TSCH) as the medium access mechanism and IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) as the routing protocol, it is possible to deploy WSNs with high reliability, autonomy, and minimal need for re-configuration. One of the drawbacks of this communication architecture is the low efficiency of its deployment process, during which it may take a long time to synchronize and connect all the devices in a network. This paper proposes an analytical model to characterize the process for the creation of downstream routes in RPL, whose transmission of multi-hop messages can present complications in scenarios with a multitude of interfering nodes and resource allocation based on minimal IPv6 over the TSCH mode of IEEE 802.15.4e (6TiSCH). This type of multi-hop message exchange has a different behaviour than the multicast control messages exchanged during the synchronization phase and the formation of upstream routes, since the number of interfering nodes changes in each retransmission., The research leading to these results is part of the i4Q project that has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 958205.

The effectiveness of post-tensioning in enhancing the fracture resistance of glass beams depends on the level of compressive pre-stress introduced at the glass edge surface that will in service be exposed to tensile stresses induced by bending. Maximum pre-load that can be applied in a post-tensioned glass beam system, yielding maximum compressive pre-stress, is limited by various failure mechanisms which might occur during post-tensioning. In this paper, failure mechanisms are identified for a post-tensioned glass beam system with a flat stainless steel tendon adhesively bonded at the bottom glass edge, including the rupture of the tendon, glass failure in tension and adhesive/glass failure in the load introduction zone. Special attention is given to the load introduction failure given that the transparent nature of glass limits the use of vertical confinement usually applied in concrete. An analytical model for determination of the allowable pre-load in post-tensioned glass beams is proposed, based on the model applied for externally post-tensioned concrete beams. The model is verified with the results of a numerical model, showing good correlation, and applied in a parametric study to determine the influence of various beam parameters on the effectiveness of post-tensioning glass beams.

This paper presents an analytical model of the dynamic interrelationships between education, creativity, and happiness based on both theoretical insights and recent empirical neurological studies. In the model, the outcome is conditional on individual intelligence and risk aversion. Specifically, it focuses on two main determinants of creativity (divergent and convergent thinking), and compares two main educational policies (scholarships vs. training) in terms of their impacts on the happiness gained from creativity in the general and healthy population. An empirical test is provided by matching the model’s predictions with the results of recent neuroscience research. Numerical simulations suggested that improving convergent thinking is more important than improving divergent thinking for creativity to generate happiness throughout an individual’s life, provided both divergent and convergent thinking have achieved a sufficiently large degree; and that unstructured training in divergent thinking (e.g., in accounting schools) is necessary to reach richer but less intelligent people, whereas scholarships or unstructured training in convergent thinking (e.g., in art schools) are necessary to reach more intelligent but less rich people.

This paper describes a dynamic system for the interrelationships between happiness and health that considers three main attitudes to life: α, β, and γ for Aristotelian, Epicurean, and Stoic, respectively. All variables that have been shown by empirical and theoretical studies to affect individual health and happiness are included (i.e., employment, occupation, education, ethical freedom, equity in achievements). Three main approaches are considered: behavioural and statistical ex-ante, and ex-post behavioural. A model is developed to rank the three attitudes in terms of health for a given happiness level, and consequently, provide insights into which attitude should be adopted by each individual, according to their characteristics: individuals in Protestant and non-Protestant Christian societies should adopt β and γ attitudes, respectively; educated individuals should adopt a γ attitude; and poor individuals should adopt an α attitude. Based on this analysis, this paper provides insights into which attitude actually is adopted by each society by comparing predicted health and achievement levels with the observed life expectancy at birth and per capita gross domestic product levels in 107 countries, thus providing an empirical test of the analytical model. This analysis revealed a prevalence of β attitudes in Protestant Developed Countries, with larger γ shares in less income-unequal countries; a prevalence of γ attitudes in non-Protestant Christian Developed Countries, with larger β shares in more income-unequal countries; a prevalence of α attitudes in Muslim Less Developed Countries, with larger γ shares in more educated countries; and a prevalence of β attitudes in more educated atheist and Jewish countries.

In both the chemical and mechanical pulping process, the logs are cut into wood chips by a disc chipper before fibre separation. To make the wood chipping process more efficient, one have to investigate in detail the coupling between process parameters and the quality of the chips. One objective of this thesis was to obtain an understanding of the fundamental mechanisms behind the creation of wood chips. Another objective with the thesis was to investigate whether it was possible to, in a way tailor the chipping process so as to reduce the energy consumption in a following mechanical refining process. Both experimental and analytical/numerical approaches have been taken in this work. The first part of the experimental investigations, were performed with an in-house developed chipping device and a digital speckle photography equipment. The results from the experimental investigation showed that the friction between the log and chipping tool is probably one crucial factor for the chip formation. Further more it was found that the indentation process is approximately self-similar, and that the stress field over the entire crack-plane is critical for chip creation. The developed analytical model predicts the normal and shear strain distribution and to be more specific, the model can predict the compressive stresses parallel to the fibre direction for an assumed linear elastic and orthotropic material. The analytical distributions were found to be in reasonable agreement with the corresponding distributions obtained from a finite element analysis. To be able to study the chipping process under realistic conditions, which for example means to use chipping rates representative for a real wood chipper, a laboratory chipper was developed. Details regarding the chipper and how to evaluate the force measurements are given together with an example of how the force on the cutting tool (the knife) varies with time during cutting. To investigate the influence of a certain chipping process parameter, the chips were after production in the laboratory chipper, refined in a pilot refiner during conditions optimized for TMP (thermomechanical pulp) and CTMP (chemithermomechanical pulp) processes. It was concluded that the details concerning the chip process had a large impact on e.g. the energy consumption in both first stage and second stage refining. Results showing this are given in this thesis. För både kemisk och mekanisk pappersmassa så tillverkas flis av trädstockar med hjälp av en skivhugg innan fibrerna separeras. För att göra flisningsprocessen mer effektiv, måste kopplingen mellan processparametrar och fliskvalitet studeras. Ett mål med denna avhandling är att ge fundamental kunskap om mekanismerna bakom bildandet av träflis. Både experimentella och analytiska/numeriska metoder har använts i detta arbete. De experimentella undersökningarna har gjorts med hjälp av egen utvecklad utrustning. Resultaten från den experimentella undersökningen visar att friktionen mellan stammen och flisningsverktyget har betydelse vid flisning. Vidare observerades det att inträngnings processen är approximativt självlik (self similar) och att det är spänningsfältet över hela sprickplanet som är kritiskt för bildandet av en flis. Den utvecklade analytiska modellen förutsäger normal- och skjuvspänningsfördelningen över sprickplanet och kan mer specifikt förutsäga den kompressiva belastning som verkar parallellt fiberriktningen i ett linjärt elastiskt och ortotropt material (trä). De analytiskt bestämda fördelningarna stämmer relativt väl överens med motsvarande fördelningar beräknad med finit element analys. För att kunna studera flisningsprocessen under realistiska förhållanden, vilket bl.a. betyder att skärhastigheter som är representativa för en verklig process skall användas, så utvecklades inom ramen för avhandlingsarbetet, en laboratoriesflishugg. Detaljer rörande flishuggen samt hur uppmätta lastsignaler skall utvärderas ges tillsammans med ett exmpel på hur kraften på skärverktyget (kniven) varierar under ett skärförlopp. Inverkan av en viss flisningsprocessparameter undersöktes genom att flis tillverkades i laboratorieflishuggen varefter de raffinerades i en pilotraffinör under förhållanden som var optimerade för TMP (termomekanisk massa) och CTMP (kemitermomekanisk massa) processerna. Det konstaterades att detaljer i flisningsprocessen hade stor inverkan på t.ex. energiåtgången i både första stegs – och andrastegsraffinering. Resultat som verifierar detta ges i avhandlingen. At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Submitted. Paper 5: Submitted.

Recent experimental results based on the digital image correlation technique (U. Eitner, M. Köntges, R. Brendel, Solar Energy Mater. Solar Cells, 2010, 94, 1346-1351) show that the gap between solar cells embedded into a standard photovoltaic laminate varies with temperature. The variation of this gap is an important quantity to assess the integrity of the electric connection between solar cells when exposed to service conditions. In this paper, the thermo-elastic deformations in photovoltaic laminates are analytically investigated by developing different approximate models based on the multilayered beam theory. It is found that the temperature-dependent thermo-elastic properties of the encapsulating polymer layer are responsible for the deviation from linearity experimentally observed in the diagram relating the gap variation to the temperature. The contribution of the different material constituents to the homogenized elastic modulus and thermal expansion coefficient of the composite system is also properly quantified through the definition of weight factors of practical engineering use. Copyright © 2011 by Institution of Mechanical Engineers.

This paper presents and explores an analytical, research-based model for computational empowerment in K-9 education. The model, entitled DORIT (“Do your Own Research In Technology”), contributes to Child-Computer Interaction research by providing scaffolding for teachers to create teaching activities emphasising a critical inquiry approach to computational empowerment. We present the DORIT model, its research base and report from a study where 18 in-service teachers took part in codesigning and testing lesson plans based on the model for grades 1, 6, 7 and 9. The lesson plans serve as proof-of-concept demonstrations of how the DORIT model can scaffold teaching activities. We further analyse how the teachers used the model in practice, and report from post-interviews with the teachers regarding their experiences with the model. We conclude the paper by discussing the potentials and challenges of the DORIT model to support computational empowerment in future CCI research.

In this paper, the analytical determination of volumic eddy-current losses in rectangular-shaped conductive massive parts is presented with experimental validations. Eddy currents, as well as the resulting volumic losses, are generated by a sinusoidal spatially uniform applied magnetic field. A U-shaped electromagnetic device with a flat mobile armature (or adjustable air gap) is used to measure the eddy-current losses. The experimental device, its instrumentation, and the conductive massive parts are presented in detail in the paper. Thereafter, the magnetic field distribution applied on the conductive massive parts, which is the mean input data for the eddy-current loss model, is studied. A two-dimensional (2D) numerical model, under the FEMM software, for the magnetic field calculation was also developed. A comparative analysis between the experimental measurements and the numerical results allowed the distribution of the applied magnetic field to be accurately validated. In the final phase, the objective was to estimate the volumic eddy-current losses in rectangular-shaped aluminium conductive massive parts generated by the variation of this applied magnetic field. An analytical model, based on the Maxwell–Fourier method, for the accurate prediction of eddy-current losses has also been developed. An electromagnet with and without the conductive massive parts is characterized in terms of power consumption. By using the power conservation method (i.e., Boucherot’s theorem), the eddy-current losses could be quantified experimentally. The influence of segmentation is also studied. The analytical results are compared to the experimental test results.

SUMMARY: In order to model the wood chipping process, the primary process parameters have been identified and their first order interaction studied. The model is analytical and incorporates, in particular, the influence of sliding friction between the wood chipping tool and the log. To estimate the accuracy of the analytical model, a Finite Element (FE) analysis of the problem considered was also performed. The analytical model and the FE analysis are both restricted to small deformations and linear elastic orthotropic material behaviour. The most severe limitation with both the analytical and the FE model is the assumption of linearly elastic material. On the other hand, it is felt that existing models of anisotropic plasticity in metals are lacking too much of physical relevance, if applied to wood. The analytical model predicts the normal and shear strain distribution in the crack-plane prior to crack initiation. The analytical distributions are in reasonable agreement with the corresponding distribution of the FE analysis. Based on experimental findings, it is suggested that the stress field over the entire crack-plane, in conjunction with the stress field close to the tip of the chipping tool, are critical for chip creation, rather than just the latter. Flisningsprocessen

This paper discusses the design of a cylindrical test section subjected to a dynamic internal pressure for severe accident experiments performed at CEA. A commonly used method consists in computing the static equivalent response of the structure and then applying DLF coefficients. In this paper, Dynamic Load Factor (DLF) coefficients are obtained for cylinders. Based on a cylinder subjected to a stepped internal pressure, a set of dynamic equations is set up using the membrane theory with a modal approach (bending moments are neglected with this theory). As already commonly established, it is found that radial and axial displacements are coupled, resulting in a Multi-Degree Of Freedom (MDOF) model with coupling. The maximum DLF of the cylinder is therefore determined for both radial and axial displacements. It is found that the axial DLF reaches a maximum value when there is a specific ratio between the radius and the length (parameter $$\pi R/L$$ equal to 1.0), while the radial DLF does not depend on the geometry. Results are compared to Finite Elements dynamic simulations. On the whole, the dynamic results are validated for long cylinders (i.e. $$\pi R/L\le 0.1$$ ). However, differences in the axial displacement tend to increase with an increase in the ratio $$R/L$$ (shorter cylinders). The regular value of 2.0 established for the Single Degree Of Freedom model and for both axial and radial directions is exceeded when the radial and axial modes are coupled. The difference can be significantly higher (DLF $$\ge$$ 3.9).

Single-ended resonant converters such as Class-E inverters have been widely considered as a potential topology for small- and medium-power wireless power transfer (WPT) applications, which feature compact circuits, low switching losses, and cost benefits, as they only use a low-side switch with a simple gate driver. However, there remains a practical challenge in the design of voltage stress, efficiency, and power density. In this paper, a single-ended resonant converter with a primary parallel resonant-matching network is investigated to absorb the bulky input-choke inductors of the Class-E inverters into the coil inductance. The analytical expressions for all the converter parameters are derived based on time-domain resonant waveforms, including: (1) analysis of critical zero-voltage switching (ZVS) conditions and (2) power transfer capabilities under the given maximum switch voltage stress. Furthermore, this paper elaborates on the design methodology of the proposed single-ended resonant converters, and an optimal operating point is chosen to ensure soft-switching operation and rated power. Finally, the accuracy of the proposed model is verified by simulation and experimental results.

This paper studies the phenomenon of sloshing in the field of automatic machines for packaging liquid products, with specific reference to containers with planar motions. After introducing two equivalent discrete models based on a mass-spring-damper system borrowed from the literature (one linear and one non-linear), a novel method is proposed to evaluate the sloshing height of the liquid, namely the deviation of its free surface at the wall of the container from the equilibrium condition. The merits of this method are that it is easy to use, requiring no experimental evaluation of the system parameters or computationally expensive fluid dynamic simulations, and it gives good results also for highly dynamical motions. Moreover, though this paper focuses on cylindrical containers performing rectilinear movements, the presented technique can be extended to containers of arbitrary shape and generic planar motions. The method is validated by experimental tests using cylindrical containers of different dimensions and many rectilinear motion laws with maximum accelerations up to $12~m/s^{2}$ . The results are compared with those obtained by using other methods of equal complexity available in the literature, showing the effectiveness of the proposed technique.

The structural discontinuities in the form of air gaps in transformer cores cause the concentration of electromagnetic force, which is an important source of transformer vibration and noise. In this paper, an engineering model of magnetic flux density and electromagnetic force density on transformer core discontinuities is analytically developed. Based on a reasonable structural simplification and assumptions, magnetic flux density and electromagnetic force density are deduced as explicit functions of the geometric, material, and electrical excitation characteristics of the gap region and the transformer core. The accuracy of the established model is validated by the finite element method (FEM) combined with a magnetic measurement experiment. According to this engineering model, the electromagnetic force density can be reduced by decreasing the gap ratio and increasing the gap thickness to a reasonable level. The outcome of this paper can help to understand the physical mechanism of the electromagnetic force generated by core air gap discontinuities, which is meaningful for noise control and the condition monitoring of transformers.

The importance of the retaining structures is crucial in geotechnical engineering and the accurate determination of static and seismic earth pressures and natural frequency is important for study the dynamic behavior of these structures. Usually analytical formulas which do not consider the earth pressures behind retaining structure are used. An analytical model for predicting the natural frequency of retaining structures including the earth pressures by failure wedges is proposed in the present analysis. The model considers the effect of Coulomb and Mononobe Okabe failure wedges. Backfill material is considered in the analysis as cohesionless. The failure wedge is an important factor which should be considered in determining the natural frequency of retaining structures. As the weight of failure wedge increases the natural frequency decreases significantly. The current model is validated using several analytical models reported in the literature of the earlier researcher.

Gas diffusion layers (GDLs) are the most rigid layers in a 5‐layer or 7‐layer membrane electrode assembly (MEA) of a proton exchange membrane fuel cell. Therefore, in the fuel cell analysis, the mechanical properties of GDLs have a great impact on the stress distribution of the membrane as well as the performance of the whole cell. However, the mechanical properties of GDLs are not sufficiently studied. Nonlinear behavior of GDLs under cyclic compression is discussed rarely in literature. The existing model takes both constraints into consideration, but due to a geometrical oversimplification of the carbon paper microstructure, it shows some deviation, which cannot be overcome by selecting appropriate parameters. In this paper, the geometry of carbon paper microstructure has been reanalyzed. Based on the improved geometry formula, a modified model of carbon paper GDL is presented and verified by experimental data. Furthermore, both the experimental mechanical characteristics are achieved as support data for the improved model.

This paper deals with the analysis and suppression of detent effect in the magnetic lead screw (MLS), which is equipped with parallel magnetized permanent magnet (PM) segments to approximate the helical PM for manufacturing simplicity. The detent effect is caused by the non-uniform magnetization along the helical PM, and behaves as both thrust force ripple and torque ripple during the transmission process. In this paper, a three-dimensional (3-D) analytical model of the MLS is established to analyze and predict the air-gap magnetic field, and the thrust force and torque are then derived, as well as their ripple components. It demonstrates that the harmonic order of the ripples is solely dependent on PM segments' quantities per helix turn on both the nut and screw. The analytical analysis is verified by extensive 3-D numerical computations. The impact of load angel and quantities of PM segments on the detent effect are investigated. It's shown that the torque ripple suffers more seriously than thrust force ripple, and both ripple percentages drop with the increase of load angle. And it is highlighted that larger least common multiple of PM segments' quantities on screw and nut is conducive to improving the average values of thrust force and torque, and reducing the detent effect.

Switched Reluctance Machines (SRMs) are gaining more attention due to their simple, and rugged construction, low manufacturing cost, and high-speed operation capability. An electromagnetic model of the machine is needed in the design, and analysis processes. The required accuracy level of the model depends mainly on the application. A high-fidelity model is required to achieve a good design, and predict the performance accurately. However, it requires high computational cost, and longer simulation time. Other fast, and less-comprehensive models with less computational burden could be utilized in the design, and analysis of the motor drives. This paper extensively analyzes various electromagnetic modeling techniques of SRMs. Analytical, numerical, and hybrid models are considered. The paper investigates analytical models that are based on Maxwell's equations in addition to interpolation, and curve fitting techniques. Numerical techniques such as Finite Element Method (FEM), and Boundary Element Method (BEM) are presented. Moreover, Magnetic Equivalent Circuit (MEC) method is discussed. Finally, potential research areas are proposed for the electromagnetic modeling of SRMs.

In this paper, a new accurate and comprehensive analytical model of harmonic and interharmonic distortion produced by a single-phase AC/DC diode rectifier (DBR) is presented. Its main and new characteristic is the ability to consider the presence of interharmonics in addition to harmonics in the voltage at the terminals of DBR due to the background voltage. Analytical expressions able to predict DC voltage and AC current in time domain are obtained. Several numerical and experimental tests have been performed, but in this paper only the numerical and experimental validation on a commercial equipment (i.e. CFL lamp) showing very accurate results is reported for space limitations.

The problem of searching for damage on overhead lines due to a lightning discharge is relevant for consumers of electricity and its suppliers. A direct lightning strike into power line elements leads to the destruction of insulators, breakage of wires and cables, and a consumer disconnection. The main task of the maintenance staff is to search for damage that occurs after a lightning discharge. Usually, special devices are used, they are installed in substations and based on the wave method, the visual method is also used. The paper proposes a model for detecting likely damage to power transmission line elements by creating a detailed database on the region's power transmission line and combining this database with a real-time archive of lightning discharges. The model in accordance with the proposed algorithm will make it possible to compile a list of supports likely to be affected by a lightning discharge, to identify the affiliation of these supports to specific power lines, and to notify the maintenance personnel of these power lines about the coordinates and supports of the power lines, where damage is possible. The model has a low cost and operating cost, can be easily deployed in any power system, but requires sufficient accuracy to detect lightning discharges and determine their coordinates. The solution to the problem of detection accuracy comes down to installing in the region a certain number of lightning direction finders of a particular system. The paper considers these issues on the example of the power system of the Murmansk region and lightning direction finders of the Blitzortung system.

International audience; This paper described a comparison between a numerical Finite Element Analysis (FEA) and an analytical approach in order to extract the thermal time constants and the thermal resistances of simple but realistic structures. Understanding the complex contribution of multidimensional thermal spreading, the effect of multiple layers, and the correlation with the heat source length is mandatory due to the severe mismatch of thermal expansion in different epitaxial layers and high operating temperatures. This is especially true on GaN HEMT (High Electron Mobility Transistor) with the continuous decrease of the gate length and the increase of the power density. Moreover, in this paper, we extracted the time constants with a Model Order Reduction (MOR) technique based on the Ritz vector approach with inputs coming from the FE matrices. It was found that the time constants obtained by an analytical solution and a model order extraction from FEA were exactly the same. This result validated the idea that our MOR technique provides the real time constants and resistances for our device structures and in this case unified the analytical world with the numerical one.

Conventional concrete material shows relatively low ductility and energy dissipation capacity under high strain rate tensile loads. The use of steel fibers into concrete can significantly improve the tensile behavior of concrete subjected to high strain rate loads by bridging the concrete crack surfaces using the fibers, resulting in a high impact resistance and energy dissipation capacity. Experimental research evidenced that the parameters of volume fraction, aspect ratio and tensile strength of steel fibers affect the characteristics of steel fiber reinforced concrete (SFRC) composite materials under high strain rate tensile loads. However, the existing design codes, i.e. CEB-FIP model code 1990 and fib model code 2010, recommend the design formulations for the prediction of the behavior of normal concrete under different strain rate loads, which are only the function of strain rate of the loads. Accordingly, development of the design models to predict the behavior of SFRC materials when subjected to high strain rate loads is still lacking in the literature. Hence, the current paper aims to improve the design models recommended in the existing design codes (e.g. fib model code 2010) using artificial neural network approach in order to precisely predict the tensile behavior of SFRC materials by considering the effects of the important parameters (such as volume fraction, aspect ratio and tensile strength of steel fibers), besides the strain rate load effect. Finally, the predictive performance of the proposed model was evaluated by comparing with the relevant experimental results., The study reported in this paper is part of the project “PufProtec - Prefabricated Urban Furniture Made by Advanced Materials for Protecting Public Built” with the reference of (POCI-01-0145-FEDER-028256) supported by FEDER and FCT funds. The second author also acknowledges the support provided by FEDER and FCT funds within the scope of the project StreColesf (POCI-01-0145-FEDER-029485).

This paper deals with analytical modelling of piezoelectric energy harvesting systems for generating useful electricity from ambient vibrations and comparing the usefulness of materials commonly used in designing such harvesters for energy harvesting applications. The kinetic energy harvesters have the potential to be used as an autonomous source of energy for wireless applications. Here in this paper, the considered energy harvesting device is designed as a piezoelectric cantilever beam with different piezoelectric materials in both bimorph and unimorph configurations. For both these configurations a single degree-of-freedom model of a kinematically excited cantilever with a full and partial electrode length respecting the dimensions of added tip mass is derived. The analytical model is based on Euler-Bernoulli beam theory and its output is successfully verified with available experimental results of piezoelectric energy harvesters in three different configurations. The electrical output of the derived model for the three different materials (PZT-5A, PZZN-PLZT and PVDF) and design configurations is in accordance with lab measurements which are presented in the paper. Therefore, this model can be used for predicting the amount of harvested power in a particular vibratory environment. Finally, the derived analytical model was used to compare the energy harvesting effectiveness of the three considered materials for both simple harmonic excitation and random vibrations of the corresponding harvesters. The comparison revealed that both PZT-5A and PZZN-PLZT are an excellent choice for energy harvesting purposes thanks to high electrical power output, whereas PVDF should be used only for sensing applications due to low harvested electrical power output.

The term “travelling fire” is used to label fires which burn locally and move across the floor over a period of time in large compartments. Through experimental and numerical campaigns and while observing the tragic travelling fire events, it became clear that such fires imply a transient heating of the surrounding structure. The necessity to better characterize the thermal impact generated on the structure by a travelling fire motivated the development of an analytical model allowing to capture, in a simple manner, the multidimensional transient heating of a structure considering the effect of the ventilation. This paper first presents the basic assumptions of a new analytical model which is based on the virtual solid flame concept, a comparison of the steel temperatures measured during a travelling fire test in a steel-framed building with the ones obtained analytically is then presented. The limitations inherent to the analyticity of the model are also discussed. This paper suggests that the developed analytical model can allow for both an acceptable representation of the travelling fire in terms of fire spread and steel temperatures while not being computationally demanding, making it potentially desirable for pre-design.

Electrochemical reduction of CO2using renewable energy is a promising avenue for sustainable production of bulk chemicals. However, CO2electrolysis in aqueous systems is severely limited by mass transfer, leading to low reactor performance insufficient for industrial application. This paper shows that structured reactors operated under gas-liquid Taylor flow can overcome these limitations and significantly improve the reactor performance. This is achieved by reducing the boundary layer for mass transfer to the thin liquid film between the CO2bubbles and the electrode. This work aims to understand the relationship between process conditions, mass transfer, and reactor performance by developing an easy-to-use analytical model. We find that the film thickness and the volume ratio of CO2/electrolyte fed to the reactor significantly affect the current density and the faradaic efficiency. Additionally, we find industrially relevant performance when operating the reactor at an elevated pressure beyond 5 bar. We compare our predictions with numerical simulations based on the unit cell approach, showing good agreement for a large window of operating parameters, illustrating when the easy-to-use predictive expressions for the current density and faradaic efficiency can be applied.

This paper discusses modeling the behavior and prediction of fracture of brittle materials. Numerous publications show that progress in this area is characterized by the emergence of a number of new models that meet the requirements of the mining industry, construction and other engineering practices. The authors focus only on one class of models, paying special attention to the compromise between simplicity of solution and versatility of the model. A new version of the model is proposed, taking into account the advantages of previous models. We present a differential energy criterion for brittle fracture substantiated, according to which, fracture occurs at a certain ratio of dissipated and stored (elastic) energy. Fracture is considered as the end of the deformation process with a virtual transformation of the initial material almost without cracks into a real material with cracks. The highest and lowest elastic moduli are analytically determined, respectively, on the ascending and descending branches of the stress–strain curve. A graphical version of the algorithm for determining the brittle fracture point on the post-peak branch of the stress–strain curve is proposed. The modeling results are consistent with the experimental data known from the literature.

Flange joints with spigots are widely used in aero-engines. The spigot will restrict the shear slipping between flanges, which, in turn, affects the stiffness characteristics of the joint. The current model and research on flange joints without spigots may not be suitable for the dynamic characteristics of aero-engines. Moreover, the complexity of contact pairs limits the application of the flange joint finite element (FE) model in aero-engine dynamics analysis. Therefore, a simplified analytical model of a flange joint with a spigot is proposed in this paper. First, the stiffness characteristic of the flange joint with a spigot is studied using the FE method. Second, a corresponding experiment is executed to verify the result of the FE analysis. Furthermore, based on the former FE and experimental analysis, one section of a flange joint is simulated by the Jenkins friction model and a spring. Then, a simplified analytical model of the entire flange joint is built according to the different statuses of each section. Finally, a simulation analysis of the stiffness characteristic is performed. The result shows that the simplified analytical model can be utilized to describe the bending stiffness characteristic of the flange joint with a spigot.

The Exner equation in conjunction phenomenological sediment transport models is widely used for mathematical modeling non-cohesive river bed. This approach allows to obtain an accurate solution without any difficulty if one models evolution of simple shape bed. However if one models evolution of complex shape bed with unstable soil the numerical instability occurs in some cases. It is difficult to detach this numerical instability from the natural physical instability of bed. This paper analyses the causes of numerical instability occurring while modeling evolution of complex shape bed by using the Exner equation and phenomenological sediment rate models. The paper shows that two kinds of indeterminateness may occur while solving numerically the Exner equation closed by phenomenological model of sediment transport. The first indeterminateness occurs in the bed area where sediment transport is transit and bed is not changed. The second indeterminateness occurs at the extreme point of bed profile when the sediment rate varies and the bed remains the same. Authors performed the closure of the Exner equation by the analytical sediment transport model, which allowed to transform the Exner equation to parabolic type equation. Analysis of the obtained equation showed that its numerical solving does not lead to occurring of the indeterminateness mentioned above. Parabolic form of the transformed Exner equation allows to apply the effective and stable implicit central difference scheme for this equation solving. The model problem of bed evolution in presence of periodic distribution of the bed shear stress is carried out. The authors used the explicit central difference scheme with and without filtration method application and implicit central difference scheme for numerical solution of the problem. It is shown that the explicit central difference scheme is unstable in the area of the bed profile extremum. Using the filtration method resulted to increased dissipation of the solution. The solution obtained by using the implicit central difference scheme corresponds to the distribution law of bed shear stress and is stable throughout the calculation area.

The aim of this paper is to tackle the design of synchronous reluctance machines with transverse laminated rotor for high-speed applications by means of an analytical model. In high-speed applications, the mechanical design greatly affects the motor performance in terms of torque density and power factor. In fact, as the rated speed increases, the radial ribs thicknesses increase as well to ensure the rotor structural integrity against the centrifugal force. This increases the quadrature flux and, therefore, the rotor anisotropy gets worse. Hence, the optimal rotor design is the result of a compromise between mechanical and magnetic aspects. The purpose of this paper is twofold: First, to develop an analytical model that links the maximum average torque to the rated speed, and second, to determine the maximum power that can be generated by a specific rotor geometry. The analytical approach allows a fast motor design and analysis so that a rapid extrapolation of the results to different machine size is possible. Finite element analysis is used only to validate the final results.

The paper deals with some new results on the averaging theory approach for the analysis of feedback controlled pulsewidth modulation power electronic converters. It develops some considerations regarding the averaging approximation of time-variant differential systems proving an analytical relationship between the accuracy with which the solution of the averaged model converges to the solution of the original time-variant model (i.e., the switched model) and the switching frequency of the converters. This relation is valid both for stable and unstable systems. Moreover, this paper confirms, as corollary, that under suitable conditions (verified during the standard operations of the power electronic converters) the averaged model uniformly converges to the switched model.

International audience; This paper describes the study of an original ("power electronic-less") AC electrical architecture for propulsive purposes in aeronautics. This architecture is composed of two or more Permanent Magnets Synchronous Machines (PMSM) directly linked to each other by an AC bus, one in generator mode driven by a gas turbine and all the other PMSM in motor mode, each one driving a propeller. The simple architecture with only two PMSM-one generator and one motor-will be mainly developed here. Although this architecture may seem too rigid to be implemented, the absence of power electronic offers potential savings in mass and costs, which justifies its study to determine whether this architecture could be implemented and used for propelling systems or not. This paper focuses on the development of an analytical model enabling to fully describe the dynamic and permanent behaviour of such an architecture. Once this model is set, the stability of the architecture is analysed: a classical approach, with the linearization of the analytical model and the use of root locus analysis, is considered.

The present paper considers pitching wave energy converters (WECs) integrated in a floating platform, e.g., floating foundation for a wind turbine. Each WEC consists of a partially submerged wave absorber that rotates about the hinge located above the still water level under the influence of waves. Each wave absorber contains separated ballast tanks that are used to ensure the desired initial tilting angle of the absorber with respect to the floating foundation (called the rest angle). The same rest angle can be achieved by filling different ballast compartments that impacts the inertia moment about the hinge, response amplitude operator (RAO), resonance frequency of the absorber, and the power absorption performance. The exhaustive search for a suitable ballast configuration can quickly become a computationally expensive task depending on the number of ballast tanks. In this paper, the ballast optimization algorithm based on an analytical model is developed. The algorithm is applied to investigate the impact of the ballasts on the rest angle, RAO and resonance frequency of the wave absorber. It provides a base for ballast design and location for improved power absorption performance. The proposed algorithm can be adapted to the ballast optimization of other pitching WECs.

Recent advances in technology have made available numerous new monitoring systems that collect updated traffic measurements both in fixed locations and over specific corridors or paths. Such recent technological developments point to challenging and promising opportunities for Origin-Destination (OD) traffic demand estimation and forecast. Therefore, the aim of this paper is to study how to exploit available information detected by new monitoring devices in the estimation of traffic demand. Starting from the formulation proposed by Spiess (1987, 1990), in this paper a new method to estimate the traffic demand by means of Bluetooth data is proposed. It explores inherent properties of this information in an off-line (and static) context, where mathematical formulation of the estimation problem can be derived. The effectiveness of the proposed method has been investigated in an extensive plan of experiments carried out both on test networks and on a study network consisting in a part of the city of Rome, Italy, obtaining promising results in both applications.

Masonry columns often exhibit a lack of load-carrying capacity that is due to overloads and do not provide any ductility or dissipation capacity under seismic forces. Column confinement has been extensively studied as an effective technique, which could mitigate these structural vulnerabilities. The confinement of masonry columns will be studied in this paper, by considering fabric-reinforced cementitious matrix (FRCM) materials as external jackets. Due to the lack of information in the scientific literature, a new analysis-oriented model (AOM) for the prediction of the axial stress-strain law will be presented and discussed in this paper. The proposed AOM consists of a system of equations that make several assumptions: crossing the predicted peak point (strength and relative strain), crossing the ultimate point (80% residual strength and relative strain), and the horizontal tangent at the peak point and the initial (linear elastic) slope derived from the geometry and mechanical properties of the materials involved. The AOM was demonstrated to be simple and accurate, based on Pearson's test (χ2); therefore, the proposed approach could be considered for future design equations. In addition, this paper will illustrate and discuss the validation of two available design-oriented models (DOMs), which could predict the axial strength of FRCM jacketed columns, by comparing the theoretical results with a database of experimental results that is available in the scientific literature. Novel formulas for the computation of both the peak and ultimate axial strains will be further proposed, as the basis for a design procedure. Their accuracy was demonstrated by considering an experimental versus theoretical comparison.

It is generally considered that the representation of a double layer supercapacitor (DLSC) cannot be performed with the usual capacitance and resistance series connected, as it induces a relatively high level of inaccuracy in the results. In multiple previous studies, more advanced models have been developed with very different approaches: models with distributed parameter circuits, based on artificial neural networks (ANNs), fractional order, etc. A non-linear model, less complex than the previous ones and whose behavior adequately represents the DLSCs, is the one formed by a variable capacitance, dependent on its internal voltage. This paper presents a mathematical study to obtain analytical expressions of all the electrical variables of DLSCs, voltage, current, dissipated power and so on, by means of a previous model. This study is carried out considering that the DLSC is charged and discharged through a voltage source and also discharged through a resistor. In later sections, the operational conditions of the DLSC in numerous industrial applications are presented. Finally, a comparative analysis is made between the results produced by the conventional model, with constant capacitance, and the developed model. This analysis is finally followed by the conclusions.

This paper aims to develop an analytical model for the prediction of the electricity produced in a Photovoltaic Power Station (PVS). In this context, the developed mathematical model is implemented in a Simulink Model. The obtained simulation results are compared to the experimental data, the results obtained from the software Homer-Pro model, and the results given by the online PV calculator (Photovoltaic Geographical Information System), developed by the European commission. The comparison results show the reliability of the developed analytical model for specific months of the year. However, an error of 10% between simulations and experimental results is observed for July and August. This error is mainly due to the effects of humidity and dust that were not considered in the analytical model. Nevertheless, the monthly and yearly produced electricity values show the robustness of the proposed model to predict the PVS generated power. The developed model will be used as a powerful tool for data prediction and the optimization of electricity generation. This permits us to reduce the losses in power generation by optimizing the connected generating power stations to the power grid.

Solar thermal energy has the theoretical potential to deliver heat at ultra-high temperatures (>1300 K), which can enable integration with state-of-the-art thermal energy storage systems and unlock new applications, including advanced power cycles and thermal processes. Liquid metals are prospective heat transfer fluids for such systems, given their favourable thermo-physical properties, while their aggressive corrosiveness is shown to be mitigated using compatible refractory containment materials. The conventional approach of collecting concentrated solar energy typically involves intermediate solid absorbers, in form of tubes or porous structures, which are prone to thermomechanical and chemical failure under high solar radiation. This paper investigates the use of directly irradiated liquid metal (tin) film, operating between 800-1673 K, in two possible cavity configurations: A ‘reflective cavity’ and an ‘absorptive cavity’. The former employs cavity walls as internal reflectors to entrap radiation by secondary reflections until directly absorbed by the liquid metal. In the latter, the directly irradiated film is used to moderate the initial shot of concentrated solar radiation before diffusively reflecting them to the absorptive cavity walls, which perform as a radiative heat exchanger used to preheat the liquid metal. The concept performance is evaluated using an approximate quasi-steady-state energy model of the receiver. The reflective cavity performance is found strongly dependent on the optical properties of its internal surfaces, which resulted in poor efficiencies (70%) with greater insensitivity to the optical properties, hence, promoting its consideration in future developments of this concept.

Introduction. The operation of switched reluctance motor requires prior knowledge of the rotor position, obtaining from either low resolution photocoupler based position sensor or high resolution shaft encoder, to control the on/off states of the power switches. Problem. However, using physical position sensor in harsh environment will inevitably reduce the reliability of the motor drive, in which sensorless control comes into play. Novelty. In this paper, a sensorless control scheme of switched reluctance motor is proposed. Methodology. The method is based on a simple analytical model of the flux-linkage curves rather than the conventional approach that normally uses a look-up table to store all the data points of the flux-linkage curves. By measuring the phase current, rotor position can be deduced from the analytical model. Practical value. Simulation results are given and the proposed sensorless scheme is verified to provide a moderate position estimation accuracy in a wide speed range in both unsaturated and saturated conditions., Вступ. Для роботи вентильного реактивного двигуна потрібне попереднє знання положення ротора, отримане або від датчика положення на основі оптопари з низькою роздільною здатністю, або від енкодера з високою роздільною здатністю, щоб керувати станами вмикання/вимикання силових перемикачів. Проблема. Однак використання датчика фізичного положення в суворих умовах неминуче знижує надійність моторного приводу, в якому набуває чинності бездатчикове управління. Новизна. У цій роботі пропонується бездатчикова схема управління вентильним реактивним двигуном. Методологія Цей метод заснований на простій аналітичній моделі кривих потокозчеплення, а не на традиційному підході, який зазвичай використовує довідкову таблицю для зберігання всіх точок даних кривих потокозчеплення. Вимірявши фазний струм, положення ротора можна вивести з аналітичної моделі. Практична цінність. Наведено результати моделювання та перевірено запропоновану бездатчикову схему для забезпечення помірної точності оцінки положення в широкому діапазоні швидкостей як у ненасичених, так і в насичених умовах.

An important aspect that must be considered when designing micro-electro-mechanical systems (MEMS) for all domains, including robotics, is the thermoelastic damping which occurs when the MEMS material is subjected to cyclic stress. This paper is focused on a model for the thermoelastic damping developed based on the generalized thermoelastic theory with the non-Fourier thermal conduction equation. The model was implemented in MATLAB and several simulations were performed. The theoretical results show a decrease in the deflection amplitude with the increase in time. The deflection amplitude decrease was validated by the experimental investigations, consisting of measuring the loss in amplitude and velocity of oscillations as a function of time. Moreover, this paper also presents the influence of the geometric dimensions on the mentioned decrease, as well as on the initial and final values of the amplitude for several polysilicon resonators investigated in this paper.

[Abstract:] Most of the water pipe infrastructure is outdated; therefore, frequent maintenance and repair works are required. To speed up the rehabilitation work and to have a more sustainable and efficient approach, trenchless methodologies have been developed in the last decades. One of the most cost-effective trenchless methods is the so-called Cured in Place Pipeline (CIPP) method, in which a resin-impregnated liner is pulled or inverted inside the host pipe and, when cured, it restores the old pipe structural and mechanical integrity. The aim of this study is to analyse the effects of the presence of a CIPP liner in a deteriorated pipe during unsteady flow for compressible fluids. In particular, the paper deals with a new formulation to compute the celerity of the wave which produces the overpressures, when the pipe wall is composed of both the host (old) pipe and the new liner, whose thickness depends on the required mechanical characteristics. The problem is strictly dependent on the mechanical properties of the liner. In order to obtain the new formula for celerity, the linear elastic problem for multi-layered pipes has been solved. The theoretical results have been validated by performing numerical simulation analysis using a Boundary Element model, with the software BEASY™. The resulting circumferential strain is integrated in the continuity equation, deriving the new formula to compute the wave celerity. The values of the celerity are dependent on the thickness and on the elastic properties of the liner. The behaviour of several combinations of thickness of the liner and Young’s modulus values has been studied and the results have been critically shown in the paper.

Part 1: Regular Papers; International audience; Network resources are imperfect and vulnerable to failure from a wide variety of sources. Survivability is a well-researched field that focuses on strategies to prevent or reduce the harm inflicted when network elements fail. Solutions tend to either provision resources, such as backup paths, proactively so that traffic can be switched to the alternative route after a failure, or quickly find new resources to provision after failure event occurs. Current survivability solutions guarantee protection against these failures, but there is no mathematical model to calculate the network blocking probability for survivability solutions of anycast communication. In this paper, we developed new analytical models to calculate network-wide blocking performance for anycast survivability approaches. Performance results show that our models are accurate and are verified by extensive simulation results.

Freshwater is an increasingly scarce resource. Its use in the production of concrete is one important contributor to its fast depletion. Alternatively, the use of seawater for reinforced concrete production, combined with the use of glass fibre reinforced polymers (GFRP) as reinforcement, may represent an interesting solution to increase concrete sustainability. The objective of this paper is to explore this promising solution through the development of concrete compositions with seawater. Additionally, it is also an objective to assess the bond behaviour between GFRP rods and concrete, in a design perspective. The influence of concrete age, rod diameter and anchorage length were also investigated. An analytical model capable of determining the local bond stress-slip laws was used. Results demonstrated that the use of seawater had no relevant effects on neither concrete mechanical properties nor bond behaviour., The study presented in this paper is a part of the research project “NEXT-SEA: Next Generation Monitoring of Coastal Systems in a Scenario of Global Change”, financed by CCDRN and FEDER funds in the scope of the Next-sea project (NORTE-01-0145-FEDER-000032). The authors acknowledge all the companies that have been involved supporting and contributing for the development of this study, mainly: S&P Clever Reinforcement Ibérica Lda., Burgoparaíso – Unipessoal Lda., Secil, Sika Portugal – Produtos Construção e Indústria S.A. The first and the last authors wishes also to acknowledge the grants SFRH/BD/131913/2017 and SFRH/BSAB/150266/2019, respectively, provided by FCT, financed by European Social Fund and by national funds through the FCT/MCTES.

The short-term prediction of earthquakes is an essential issue connected with human life protection and related social and economic matters. Recent papers have provided some evidence of the link between the lithosphere, lower atmosphere, and ionosphere, even though with marginal statistical evidence. The basic coupling is hypothesized as being via the atmospheric gravity wave (AGW)/acoustic wave (AW) channel. In this paper we analyze a scenario of the low latitude earthquake (Mw = 6.9) which occurred in Indonesia on 5 August 2018, through a multi-instrumental approach, using ground and satellites high quality data. As a result, we derive a new analytical lithospheric–atmospheric–ionospheric–magnetospheric coupling model with the aim to provide quantitative indicators to interpret the observations around 6 h before and at the moment of the earthquake occurrence.

The effect of mass parameters on the natural vibration period of isolated bridges is discussable, especially in case of substructure mass components, because of the disagreement of different researchers about it. This is while some bridge design codes such as AASHTO guide specification, ignores substructure mass in simplified method of analysis. Current paper investigates the effects of substructure mass components on the longitudinal period of base isolated bridges. These components include: pier mass, cap beam mass, pier rotational moments of inertia, and cap beam rotational moments of inertia. In this paper, a three degree of freedom analytical model of isolated bridge in longitudinal direction is presented and the natural vibration period of this model is calculated in four cases. These cases are: (1) exact solution, (2) by ignoring the rotational moments of inertia, (3) by ignoring the cap beam mass, and (4) by ignoring the pier and cap beam mass (AASHTO model). The periods obtained from exact analytical model were compared with those obtained from finite element model and the results showed the good conformity. The results also showed that the substructure rotational moments of inertia isn’t a determinative parameter in the calculation of the first longitudinal period; while the cap beam mass have a significant impact on the longitudinal period of base isolated bridges with tall piers or stiff isolators. The ignorance of cap beam mass caused 8% error in the period of such bridges. The results showed that the simplified method of AASHTO guide specification isn't applicable in some bridges and may cause more than 10% error. By increasing the ratio of isolator stiffness to substructure stiffness, the error of period which is calculated by AASHTO model, increases.

Cet article examine les différentes composantes d’un modèle d’éducation éthique sous l’angle de la reconnaissance de la dignité humaine. Ce modèle, qui permet une lecture fine de l’éducation éthique dans un programme, se présente en sept composantes : trois composantes simples Éducation à la société (ES), Formation personnelle (FP) et Éducation à l’autre (EA) et quatre composantes à l’intersection de ces dernières (FP/EA, FP/ES, EA/ES et FP/EA/ES). Il a été développé dans le cadre de travaux menés sur l’éducation dans la francophonie. La recherche qualitative dont est issu ce modèle emprunte une logique inductive ancrée dans le corpus analysés. Au terme de l’examen des composantes de ce modèle, la conclusion est qu’une éducation éthique qui ferait de la dignité humaine un point de repère et une destination appellerait à une forme particulière de la reconnaissance de ladite dignité dans chacune des composantes dudit modèle., This paper reviews the various components of an ethics education model from the perspective of human dignity. The model, which was developed through our comparative research on ethics education in French-speaking countries, offers a nuanced reading of educational programs. This model comprises seven ethical components. Three are simple – Education for society (ES), Personal development (FP), and Education for otherness (EA) – and four are mixed (FP/EA, FP/ES, EA/ES and FP/EA/ES). The qualitative research that led to the development of the model draws on an inductive logic anchored in educational programs analyzed. After examining the model’s components, the paper concludes that an ethics education that uses human dignity as both a key reference and as a goal requires a different form of recognition in each component of the analytical model.

Torque ripples cause acoustic noise, fluctuation in speed, vibration, and reduce lifetime of the motor. The double salient structure of Flux Switching Motor (FSM) has a high air-gap permeance variation that produces high torque ripples. This paper presents an analytical model to reduce air-gap permeance variation and torque ripples of the proposed octane modular stator 8slots-6poles single-phase Electrically Excited (EE) FSM. Furthermore, the rotor pole shaping technique is used to minimize the air-gap permeance variation and therefore, torque ripples of the proposed design are reduced. The electromagnetic performance of EEFSM is analyzed via the Finite Element Analysis (FEA) method. For the proposed design magnetic flux harmonics are reduced by 71% and back-EMF harmonics are suppressed by 48.5%. Torque ripples of the proposed EEFSM are reduced by 20%, cogging torque is diminished by 42.7% and average torque is enhanced by 5.8%. Finally, the prototype is fabricated and tested experimentally. Calculated values and experimental results are in good agreement and the difference is 3.5%-5%.

The paper is aimed at an investigation of the features of a tubular-linear synchronous quasi-Halbach machine (T-LSM) where the radially-magnetized PMs are substituted by four equal segments with parallel magnetization. This substitution is done in an attempt to improve the machine cost-effectiveness which makes it a viable candidate to equip free-piston engine-based series hybrid propulsion systems. The study is initiated by an analytical formulation of the air gap flux density considering (i) the case of the conventional quasi-Halbach T-LSM and (ii) the case of the segmented pole one. The comparison between the two T-LSMs is extended to a 3D finite element analysis (FEA)-based investigation of their no- and on-load features. Following the prototyping of the quasi-Halbach T-LSM with segmented poles, selected features predicted by 3D FEA are experimentally-validated. It is shown that while the PM segmentation slightly affects the machine back-EMF and cogging force, it has a remarkable fallout on its force production capability which makes it necessary the assessment of the cost-performance trade-off.

In distributed systems, the occurrence of an action can give information about the occurrence of other actions. This can be an unwanted situation when 'high' actions of the system need to be kept secret, while allowing users to observe 'low' actions. If it is possible to deduce information about occurrence of high actions by observing only low actions, then the system suffers from an unwanted information flow. 'Reveals' and 'excludes' relations were introduced for modelling and analysing such an information flow among actions of a distributed system that is modelled via Petri nets. In this paper, we provide a formal basis for computing reveals and excludes relations of 1-safe free-choice Petri nets. We introduce the 'maximal-step computation tree' to represent the behaviour of a distributed system under maximal-step semantics. We define a finite prefix of the tree called 'full prefix' and we show that it is adequate for analysing information flow by means of reveals and excludes relations.

Brushless doubly fed reluctance generator (BDFRG) provides a good substitute for the doubly fed induction generator for the wind energy applications due to the nonexistence of the slip rings. Real time modelling of the BDFRG is a challenge due to the high leakage inductance of the stator windings. While the magnetic saturation of the iron parts affects the inductances values, therefore studying the effect of magnetic saturation on the BDFRG performance is important. In this paper, a BDFRG model including iron saturation is built. The finite element (FE) analysis using FEMM software is used to generate the relationship between the generator currents and the inductances, the generated data are recorded in a lookup table. A Simulink model of the BDFRG driven wind turbine, with two cases of constant and variable inductances, are developed and verified with FE analyses at range of wind speeds above and below the synchronous speed. The lookup table proposes is verified using finite element analysis at different modes of operation of wind speed and compared with the constant inductance model to show the importance of saturation inclusion in the generator model for accurate generator modelling representation.

Multilateral well drilling technology has recently assisted the drilling industry in improving borehole contact area and reducing operation time, while maintaining a competitive cost. The most advanced multilateral well drilling method is Fishbone drilling (FbD). This method has been utilized in several hydrocarbon fields worldwide, resulting in high recovery enhancement and reduced carbon emissions from drilling. FbD involves drilling several branches from laterals and can be considered as an alternative method to hydraulic fracturing to increase the stimulated reservoir volume. However, the expected productivity of applying a Fishbone well from one field to another can vary due to various challenges such as Fishbone well design, reservoir lithology, and accessibility. Another challenge is the lack of existing analytical models and the effect of each Fishbone parameter on the cumulative production, as well as the interaction between them. In this paper, analytical and empirical productivity models were modified for FbD in a dry gas reservoir. The modified analytical model showed a higher accuracy with respect to the existing model. It was also compared with the modified empirical model, which proved its higher accuracy. Finally, machine learning algorithms were developed to predict FbD productivity, which showed close results with both analytical and empirical models.