878 research outputs found
Modeling and output tracking of transverse flux permanent magnet machines using high gain observer and RBF Neural network
No full textThis paper deals with modeling and adaptive output tracking of a transverse flux permanent magnet machine as a nonlinear system with unknown nonlinearities by utilizing high gain observer and radial basis function networks. The proposed model is developed based on computing the permeance between rotor and stator using quasiflux tubes. Based on this model, the techniques of feedback linearization and Hâcontrol are used to design an adaptive control law for compensating the unknown nonlinear parts, such as the effect of cogging torque, as a disturbance is decreased onto the rotor angle and angular velocity tracking performances. Finally, the capability of the proposed method in tracking both the angle and the angular velocity is shown in the simulation results. © 2005 ISA - The Instrumentation, Systems, and Automation Society
Near Time-Optimal Transient Response in DC-DC Buck Converters Taking into Account the Inductor Current Limit
No full textThis paper analyzes the general problem of
inductor current limitation in the time-optimal load transient
response of a DC-DC buck converter. The concept of currentlimited,
time-optimal control (CL-TOC) is introduced and
compared to the previously reported unconstrained timeoptimal
solutions. A fundamental tradeoff between maximum
allowed current overshoot and voltage recovery time is
recognized, and a set of design equations is developed which
provide the engineer with the necessary analytical tools for the
controller design. Furthermore, the minimum number of
switching actions required to handle a generic current-limited
TOC is determined, leading to the formulation of a minimumswitch
CL-TOC concept. Two distinct approaches for minimumswitch
digital CL-TOC are then introduced. The first method,
which is an extension of a charge-balance approach, has the
advantage of achieving the time-optimal switching sequence
without the need for a prior knowledge of the output filter LC
parameters. The second approach implements a near CL-TOC
employing the switching surface concept and defining the
current limitation in the state-space. Simulation and
experimental results are provided to demonstrate the
effectiveness of the approaches
Current-Limited Time-Optimal Response in Digitally Controlled DC-DC Converters
No full textThis paper addresses the problem of time-optimal
load-transient response in digitally controlled dc–dc buck converters
incorporating an inductor current limitation. The concept
of current-limited, time-optimal control (CL-TOC) is introduced
and compared to the conventional unconstrained time-optimal
solution. A fundamental tradeoff between maximum-allowed current
overshoot and voltage recovery time is recognized and analytically
formulated, thus providing the engineer with the necessary
analytical tools for performance evaluation. Furthermore,
the minimum number of switching actions required to handle a
generic CL-TOC transient is determined, thus leading to the formulation
of a minimum-switch CL-TOC concept. Two distinct approaches
for implementing minimum-switch digital CL-TOC are
then introduced. The first method extends a parameter-independent
time-optimal control that has the advantage of achieving the timeoptimal
switching sequence without the need for a prior knowledge
of the output filter LC parameters or input voltage. The second
approach implements a near CL-TOC employing the switchingsurface
concept and defining the current limitation in the state
space. Experimental results are provided to validate the theory
and demonstrate the effectiveness of the approaches
Deep Learning and Dynamical Systems Approaches to Critical Transitions in Socio–Climate and Complex Systems
No full textThis thesis explores how dynamical systems, stochastic processes, and deep learning can be integrated to study critical transitions in socio-climate and other complex systems. Chapter 1 establishes the conceptual foundation, introducing complex systems, tipping points, bifurcation theory, stochasticity, early warning signals, and the role of deep learning. It also highlights flickering as a precursor to collapse and motivates the importance of coupled socio-climate feedbacks. Chapter 2 develops a hybrid CNN--LSTM framework to classify bifurcations in noisy time series. Trained on synthetic dynamical models, the classifier generalises to empirical data and outperforms traditional early warning signals, offering a robust method to identify fold, Hopf, and transcritical bifurcations. Chapter 3 introduces a deep learning approach to detect flickering dynamics, noise-driven switching between alternative equilibria. The model distinguishes true flickering from noise-induced variance inflation across diverse systems and demonstrates applicability to empirical data such as palaeoclimate records and physiological signals, providing an early warning beyond variance-based methods. Chapter 4 presents a coupled socio-climate model where social behaviour feeds back on emissions and climate thresholds. Results show that social dynamics, such as faster learning rates or stronger norms, can delay or prevent climate tipping, while delays or weak norms accelerate collapse. This chapter highlights the potential of social tipping points to stabilize climate trajectories. Chapter 5 evaluates whether binary opinion models suffice to represent socio-climate interactions compared to richer spectrum models. Using replicator and Friedkin–Johnsen frameworks coupled to climate-carbon and forest-grassland systems, the study finds that binary models capture essential coupled dynamics with surprising accuracy, despite their simplicity. Together, the chapters demonstrate that combining dynamical systems theory, stochastic analysis, and deep learning yields powerful tools to anticipate tipping points. The findings advance both methodological development and practical insight, showing that human social responses can critically shape whether climate transitions are mitigated or exacerbated
A note on some Eocene benthic foraminifers of West and Central Iran, with remarks on palaeontology and biostratigraphy: Reply to Hadi and Schlagintweit comment (2024)
No full textThis article is a reply to the comment by Hadi and Schlagintweit (2024, Acta Palaeontologica Romaniae 2: 17–2) on the article by Babazadeh and Cluzel (2023, Bulletin de la Société Géologique de France 194: 1–24) about the internal structure and stratigraphic range of some benthic foraminifers from the Eocene carbonate deposits in the Shahr-e Kord and Mahallat regions of Iran. The comment focuses on the diagnosis of a limited number of species, and the introduction of new species of Eocene agglutinated foraminifers from the Mahallat region. In this reply, the disputed data are briefly reviewed and discussed in more detail. The interpretation of benthic foraminifers is based on their morphological variability and comparisons. Here the authors use re-illustrations of the types of nummulitids (Nummulites), orbitolinids (Coskinolina, Daviesiconus, Coleiconus and Barattolites), and other comparative material to confirm their determinations. Therefore, the hyaline foraminifers constitute the main subject of investigation, whereas the alveolinids are of secondary importance
Variation in pathogenicity in the Fusarium verticillioides populations isolated from maize during the growing season
No full textIn Northern Italy the main etiological agent of Fusarium ear rot in maize is Fusarium verticillioides, the major producer of fumonisins. The role of F. verticillioides population variability, on disease incidence variation has not yet elucidated, and seems to be important for resistance breeding, evolutionary risk of the pathogen, and efficacy of the agricultural management practices. One hundred eighty one F. verticillioides strains were randomly selected among F. verticillioides populations associated with maize samples collected during different maize growth stages in three fields located in Lombardia region. Pathogenicity assays of the selected F. verticillioides strains was assessed on maize by evaluating seed germination percentages and calculating the percentage infection index (I%I) concerning seed colonization, radicle decay, and coleoptile rot. Seed germination occurred still when F. verticillioides colonized the entire kernel.To investigate variation in pathogenicity within the populations, cluster and principal component (PC) analyses were computed using I%Is obtained. Observed I%Is were very variable with significant correlations between seed colonization and both radicle decay and coleoptile rot. Cluster analysis showed that isolates were grouped in three main clusters. Bi-plot of PCA revealed that F. verticillioides strains isolated at seed and at maturity stages were gathered, while strains isolated from maize debris and at seedling and pre-silking stages showed a scattered distribution. F. verticillioides pathogenicity seemed to vary according to the maize growing stages, particularly when seedborne population and strains isolated at pre-silking stages are taken into account. Information gained from the combination of clustering method and PC analysis inferred that F. verticillioides pathogenicity showed very high intraspecific variability
A note on some Eocene benthic foraminifers of West and Central Iran, with remarks on palaeontology and biostratigraphy: Reply to Hadi and Schlagintweit comment (2024)☆
No full textThis article is a reply to the comment by Hadi and Schlagintweit (2024, Acta Palaeontologica Romaniae 2: 17–2) on the article by Babazadeh and Cluzel (2023, Bulletin de la Société Géologique de France 194: 1–24) about the internal structure and stratigraphic range of some benthic foraminifers from the Eocene carbonate deposits in the Shahr-e Kord and Mahallat regions of Iran. The comment focuses on the diagnosis of a limited number of species, and the introduction of new species of Eocene agglutinated foraminifers from the Mahallat region. In this reply, the disputed data are briefly reviewed and discussed in more detail. The interpretation of benthic foraminifers is based on their morphological variability and comparisons. Here the authors use re-illustrations of the types of nummulitids (Nummulites), orbitolinids (Coskinolina, Daviesiconus, Coleiconus and Barattolites), and other comparative material to confirm their determinations. Therefore, the hyaline foraminifers constitute the main subject of investigation, whereas the alveolinids are of secondary importance
The Oligocene Avaj volcanic – plutonic complex of Central Iran: A record of magma evolution and mineral equilibria
No full textThe Avaj Oligocene volcanic – plutonic complex is part of extensive Cenozoic magmatic activity within the Urumieh-Dokhtar magmatic arc of Iran. We use whole rock geochemistry, mineral compositions and crystal size distributions (CSD) in a suite of co-genetic basalt, basaltic andesite and gabbro to determine their petrogenesis. Ca-rich cores in plagioclase (An79-86) overlap empirically modelled compositions, indicating equilibrium crystallization from melts represented by the whole-rock compositions. Clinopyroxene compositions (Mg# 74–80) are compatible with mildly fractionated mantle-derived magmas in an arc setting. Mineral-melt equilibrium is inferred from high Al contents and close correspondence between the measured DiHd and predicted KdFe–Mg (0.23–0.32) in clinopyroxenes, and Kd(Plg/melt)(An–Ab) values of plagioclase cores (0.11–0.15). Clinopyroxene-melt thermometers indicate crystallization at 1119–1173 °C for volcanic and 1099–1134 °C for plutonic rocks. Plagioclase crystal core saturation temperatures range from 1088–1162 °C (volcanic) and 1121–1163 °C (plutonic); these values overlap calculated mineral-melt equilibrium temperatures. Plagioclase CSDs are nearly straight for both volcanic and plutonic samples, with higher nucleation density and steeper slopes for the plutonic samples. Major element variations suggest the Avaj rocks represent co-genetic magmas related by fractional crystallization of the observed mineral phases. We suggest minor crustal assimilation occurred during ascent from a deeper reservoir to a shallower one; CSD data indicate longer magma residence time for plagioclase in the plutonic samples (∼117 years) compared to the residence time of basaltic samples (∼13 years)
Ultra-sensitive measurement of transverse displacements with linear photonic gears
No full textAccurately measuring mechanical displacements is essential for a vast portion of current technologies. Several optical techniques accomplish this task, allowing for non-contact sensing even below the diffraction limit. Here we introduce an optical encoding technique, dubbed “linear photonic gears”, that enables ultra-sensitive measurements of a transverse displacement by mapping it into the polarization rotation of a laser beam. In ordinary ambient conditions, we measure the relative shift between two objects with a resolution of 400 pm. We argue that a resolution of 50 pm should be achievable with existing state-of-the-art technologies. Our single-optical-path scheme is intrinsically stable and it could be implemented as a compact sensor, using cost effective integrated optics. We anticipate it may have a strong impact on both research and industry
The influence of flavonoids in maize pericarp on fusarium ear rot symptoms and fumonisin accumulation under field conditions
No full textBreeding efforts have been undertaken to increase resistance of maize to fusarium ear rot (FER) and to fumonisin accumulation. Flavonoids in the pericarp of the kernels are considered particularly able to reduce the fumonisin accumulation. The aim of this 2-year field study was to assess the effect of flavonoids on FER symptoms and fumonisin contamination in maize kernels using two isogenic hybrids, one providing pigmentation in the pericarp (P1-rr) and the other without it (P1-wr). FER incidence (FERi), FER severity (FERs), the incidence of infections caused by Fusarium spp. in symptomless kernels (FF) and fumonisin contamination (FUM) were assessed in both hybrids. Significant differences between the two hybrids were detected mainly in 2012 trials where P1-rr showed lower FERi (P<001), FF (P<005) and FUM (P<01) than P1-wr. Site, characterized by local temperature and precipitation, played a relevant role in modelling all the measured variables, as its effect was highly significant in both years, whether they were considered individually or altogether. The interaction of hybrid with location was a significant (P<0001) source of variation only for FF. FF, together with FERi, was also significantly (P<0001) influenced by the interaction of hybrid with year. In general, FUM was more influenced by year and location parameters, such as temperatures during late ripening, than by flavonoid presence in kernel pericarp. The results indicate that flavonoid pigments alone may not be an important component in the resistance of maize to fumonisin accumulation
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