5,612 research outputs found
Inflows towards active regions and the modulation of the solar cycle: a parameter study
Aims: We aim to investigate how converging flows towards active regions
affect the surface transport of magnetic flux, as well as their impact on the
generation of the Sun's poloidal field. The inflows constitute a potential
non-linear mechanism for the saturation of the global dynamo and may contribute
to the modulation of the solar cycle in the Babcock-Leighton framework.
Methods: We build a surface flux transport code incorporating a parametrized
model of the inflows and run simulations spanning several cycles. We carry out
a parameter study to assess how the strength and extension of the inflows
affect the build-up of the global dipole field. We also perform simulations
with different levels of activity to investigate the potential role of the
inflows in the saturation of the global dynamo.
Results: We find that the interaction of neighbouring active regions can lead
to the occasional formation of single-polarity magnetic flux clumps
inconsistent with observations. We propose the darkening caused by pores in
areas of high magnetic field strength as a plausible mechanism preventing this
flux-clumping. We find that inflows decrease the amplitude of the axial dipole
moment by a , relative to a no-inflows scenario. Stronger (weaker)
inflows lead to larger (smaller) reductions of the axial dipole moment. The
relative amplitude of the generated axial dipole is about larger after
very weak cycles than after very strong cycles. This supports the inflows as a
non-linear mechanism capable of saturating the global dynamo and contributing
to the modulation of the solar cycle within the Babcock-Leighton framework
Surface flux transport simulations: Effect of inflows toward active regions and random velocities on the evolution of the Sun's large-scale magnetic field
Aims: We aim to determine the effect of converging flows on the evolution of
a bipolar magnetic region (BMR), and to investigate the role of these inflows
in the generation of poloidal flux. We also discuss whether the flux dispersal
due to turbulent flows can be described as a diffusion process.
Methods: We developed a simple surface flux transport model based on
point-like magnetic concentrations. We tracked the tilt angle, the magnetic
flux and the axial dipole moment of a BMR in simulations with and without
inflows and compared the results. To test the diffusion approximation,
simulations of random walk dispersal of magnetic features were compared against
the predictions of the diffusion treatment.
Results: We confirm the validity of the diffusion approximation to describe
flux dispersal on large scales. We find that the inflows enhance flux
cancellation, but at the same time affect the latitudinal separation of the
polarities of the bipolar region. In most cases the latitudinal separation is
limited by the inflows, resulting in a reduction of the axial dipole moment of
the BMR. However, when the initial tilt angle of the BMR is small, the inflows
produce an increase in latitudinal separation that leads to an increase in the
axial dipole moment in spite of the enhanced flux destruction. This can give
rise to a tilt of the BMR even when the BMR was originally aligned parallel to
the equator
An account on the taxonomy and molecular diversity of a marine rock-pool dweller, Tigriopus fulvus (Copepoda, Harpacticoida)
The copepod genus Tigriopus Norman, 1869 is distributed worldwide in coastal rock pools and it is currently considered to include 14 valid species. Tigriopus fulvus (Fischer 1860), with its subspecies Tigriopus fulvus adriaticus Van Douwe 1913 and Tigriopus fulvusalgiricus Monard 1935, and Tigriopus minutus Bozic 1960 are currently reported to occur in the Mediterranean area, but the actual diversity of the genus is currently unknown. We aimed to assess the actual identity of Mediterranean Tigriopus populations and to elucidate their taxonomy and pattern of genetic diversity. In order to reach these goals, a fragment of a mitochondrial DNA gene (cytochrome c oxidase subunit I, COI) was sequenced to be used as a reference marker. Our data suggest the presence of a single species characterized by a noteworthy geographi-cally based genetic structure in the whole study area. The observed diversity pattern is tentatively ascribed here to a strong monopolization of the rock pools by the first immigrants that reached them. However, such a monopolization is periodically disrupted by local extinction events, which are frequent in the intrinsically unstable rock pool habitats. We propose the name “clockwork monopolization” for this pattern.El género de copépodos Tigriopus Norman, 1869 se distribuye en todo el mundo en charcas de rocas costeras y se considera
que actualmente incluye 14 especies válidas. Tigriopus fulvus (Fischer 1860), con sus subespecies Tigriopus fulvus adriaticus Van Douwe 1913 y Tigriopus fulvus algiricus Monard 1935, y Tigriopus minutus Bozic 1960 han sido descritos para el área del Mediterráneo, pero la diversidad real del género es desconocida actualmente. El objetivo de este estudio fue evaluar la identidad real de las poblaciones mediterráneas de Tigriopus y dilucidar su taxonomía y patrón de diversidad genética. Con este fin, se secuenció un fragmento del gen de ADN mitocondrial (citocromo c oxidasa subunidad I, COI) como marcador de referencia. Los resultados sugieren la presencia de una sola especie caracterizada por una estructuración genética con una notable base geográfica en toda el área de estudio. El patrón de diversidad observado aquí se atribuye tentativamente a una fuerte monopolización de las charcas de las costas rocosas por parte de los primeros inmigrantes que las alcanzan. Sin embargo, tal monopolización se interrumpe periódicamente por los eventos de extinción local, los cuales son frecuentes en los hábitats de charcas de rocas que son intrínsecamente inestables. Aquí proponemos para este patrón el nombre de “monopolización
periódica” (“clockwork monopolization”)
Local bisection for conformal refinement of unstructured 4D simplicial meshes
We present a conformal bisection procedure for
local refinement of 4D unstructured simplicial meshes with
bounded minimum shape quality. Specifically, we propose a
recursive refine-to-conformity procedure in two stages, based on
marking bisection edges on different priority levels and defining
specific refinement templates. Two successive applications
of the first stage ensure that any 4D unstructured mesh can
be conformingly refined. In the second stage, the successive
refinements lead to a cycle in the number of generated similarity
classes and thus, we can ensure a bound over the minimum
shape quality. In the examples, we check that after successive
refinement the mesh quality does not degenerate. Moreover, we
refine a 4D unstructured mesh and a space-time mesh (3D + 1D)
representation of a moving object
Mathematical Modelling and Predictive Control of Permanent Magnet Synchronous Motor Drives
The paper deals with a mathematical modellingof the three-phase Permanent Magnet Synchronous Motors(PMSM) and their model-based control. These motors areused in drives of robots and machine tools. The constructionof their mathematical model is discussed here with respectto a model-based control design. The model is composedvia mathematical-physical analysis. The analysis is outlinedin the main theoretical points. As a promising model-basedapproach, the predictive control is explained. It representsjust a promising alternative to the standard solution basedon the vector cascade control
Model Predictive Control for Offset-Free Reference Tracking
The paper deals with the offset-free reference tracking problem of the Model Predictive Control (MPC). That problem is considered for a class of the constant or occasionally changed constant reference signals. Proposed solution arises from a simple subtraction of the ARX model of two consecutive time steps. The solution is adapted to a state-space form and it corresponds to usual predictive control design without increase of the design complexity. The construction of the prediction equations and predictive controller structure is explained in the paper
THE EFFECT OF USING SCROL (SURVEY, CONNECTION, READ, OUTLINE, LOOK BACK) STRATEGY TOWARDS STUDENTS’ READING COMPREHENSION AT THE SECOND YEAR OF MTs DARUL HIKMAH PEKANBARU
The main focus of the research is to find out whether there is significant
difference between students’ reading comprehension taught by using SCROL
(Survey, Connection, Read, Outline, Look Back) strategy and students’ reading
comprehension taught by using conventional strategy. In the research, the type of
the research was quasi-experimental research. The writer used nonrandomized
control group pretest-posttest design. The writer used two classes as sample
consist of 60 students. The first class was as experimental and the second was as
control. Experimental class taught by using SCROL (Survey, Connection, Read,
Outline, Look Back) strategy and control class taught by using conventional
strategy. The technique of data collecting was observation and test. Observation
was used in order to collect the data of using SCROL (Survey, Connection, Read,
Outline, Look Back) strategy and test was used in order to collect the data of
students’ reading comprehension at the second year of MTs Darul Hikmah
Pekanbaru. The technique of data analysis used T-test formula in order to find out
the difference of students’ mean score between experimental class and control
class by using SPSS 16 version. The students’ score was compared with T-table
which considered with degree of freedom (df).
Based on the data analysis, the writer concludes that there is significant
difference between students’ reading comprehension taught by using SCROL
(Survey, Connection, Read, Outline, Look Back) strategy and students’ reading
comprehension taught by using conventional strategy with consideration to =
9.905 is higher than T-table either in significant 5 % = 2.00 or in significant 1 % =
2.65. It means that Ha is accepted and Ho is rejected. So, it can be concluded that
there is significant difference between students’ reading comprehension taught by
using SCROL (Survey, Connection, Read, Outline, Look Back) strategy and
students’ reading comprehension taught by using conventional strategy at the
second year of MTs Darul Hikmah Pekanbaru. In other words, there is a
significant effect of using SCROL (Survey, Connection, Read, Outline, Look
Back) strategy towards students’ reading comprehension at the second year of
MTs Darul Hikmah Pekanbaru
La terminología informática del futuro
Análisis de la terminología relacionada con la informática y las Nuevas Tecnologías en español y problemas hallados en su traducción del inglés
From the Monasterium Clericorum to the Studia Generalia. The catholic education in the Ius Antiquum
La exigencia de profundizar en el Misterio de salvación y cumplir fielmente la misión de difundir la Buena Nueva que le ha sido confiada por el Divino Fundador, han inducido a la Iglesia, desde el principio, a cuidar de la educación del pueblo de los redimidos, y sobre toto de los que tenían un papel de relieve en el ejercicio del munus docendi. Este trabajo de investigación supone una mirada general sobre las medidas adoptadas a lo largo de los siglos para responder en la forma mejor a dichas exigencias, desde la primera legislación conciliar hasta la constitución de los studia generalia, antecedentes de las universidades modernas y constituidos para garantizar a la consciencia la necesaria estabilidad que permite su fructífero
desarrollo.The need of examining in depth the Mystery of salvation and of fulfilling
faithfully the mission of spreading the Good News revealed by the Divine Founder,
encouraged the Church, ever since its beginning, to take care of the education of the
redeemed persons, especially of those who had an important position in the practice
of the munus docendi. This research includes a general gaze to the measures adopted
over the centuries in order to answer properly to those needs, starting with the first
council legislation, until the creation of the studia generalia, which were the
precursors of the modern universities and were created to safeguard the stability of
knowledge that is necessary in order to allow its fruitful development.Ciencias ReligiosasDerech
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