5,281 research outputs found
Codensity Lifting of Monads and its Dual
We introduce a method to lift monads on the base category of a fibration to
its total category. This method, which we call codensity lifting, is applicable
to various fibrations which were not supported by its precursor, categorical
TT-lifting. After introducing the codensity lifting, we illustrate some
examples of codensity liftings of monads along the fibrations from the category
of preorders, topological spaces and extended pseudometric spaces to the
category of sets, and also the fibration from the category of binary relations
between measurable spaces. We also introduce the dual method called density
lifting of comonads. We next study the liftings of algebraic operations to the
codensity liftings of monads. We also give a characterisation of the class of
liftings of monads along posetal fibrations with fibred small meets as a limit
of a certain large diagram.Comment: Extended version of the paper presented at CALCO 2015, accepted for
publication in LMC
Constraint on Heavy Element Production in Inhomogeneous Big-Bang Nucleosynthesis from The Light-Element Observations
We investigate the observational constraints on the inhomogeneous big-bang
nucleosynthesis that Matsuura et al. suggested the possibility of the heavy
element production beyond Li in the early universe. From the
observational constraints on light elements of He and D, possible regions
are found on the plane of the volume fraction of the high density region
against the ratio between high-and low-density regions. In these allowed
regions, we have confirmed that the heavy elements beyond Ni can be produced
appreciably, where - and/or -process elements are produced well
simultaneously.Comment: 11 pages, 7 figures, 4 Tables., accepted in Journal of Astrophysics.
arXiv admin note: substantial text overlap with arXiv:1007.046
Reply to 'Comment on 'Heavy element production in inhomogeneous big bang nucleosynthesis''
This is a reply report to astro-ph/0604264. We studied heavy element
production in high baryon density region in early universe astro-ph/0507439.
However it is claimed in astro-ph/0604264 that small scale but high baryon
density region contradicts observations for the light element abundance or in
order not to contradict to observations high density region must be so small
that it cannot affect the present heavy element abundance.
In this paper we study big bang nucleosynthesis in high baryon density region
and show that in certain parameter spaces it is possible to produce enough
amount of heavy element without contradiction to CMB and light element
observations.Comment: 7 pages, 4 figures, References added, one more reference adde
Codensity Liftings of Monads
We introduce a method to lift monads on the base category of a fibration to its total category using codensity monads. This method, called codensity lifting, is applicable to various fibrations which were not supported by the categorical >>-lifting. After introducing the codensity lifting, we illustrate some examples of codensity liftings of monads along the fibrations from the category of preorders, topological spaces and extended psuedometric spaces to the category of sets, and also the fibration from the category of binary relations between measurable spaces. We next study the liftings of algebraic operations to the codensity-lifted monads. We also give a characterisation of the class of liftings (along posetal fibrations with fibred small limits) as a limit of a certain large diagram
Practical and robust control for precision motion: AR-CM NCTF control of a linear motion mechanism with friction characteristics
This study presents the framework of the acceleration reference continuous motion nominal characteristic trajectory following (AR-CM NCTF) control system, and its effectiveness in a linear motion mechanism with friction characteristics is experimentally demonstrated in comparison with the other control methods. The overall control system comprises the feedback-loops for velocity reference and acceleration reference following controls. The AR-CM NCTF control is an enhanced continuous motion NCTF (CM NCTF) control that has been proposed for high-precision motion. It has the same structure as the CM NCTF controller with additional elements for high-precision motion. The design procedure of the AR-CM NCTF controller remains easy and is independent of friction characteristics. The usefulness and advantages of the proposed controller are shown in the experimental studies. Besides, this study also highlights the robustness of the AR-CM NCTF controller by examining its performances in point-to-point and tracking motions in the presence of mass and disturbance force variations. In
the robust performance, the AR-CM NCTF controller is compared with two types of proportional derivative control systems with disturbance observers (PDDOs). The comparative experimental results illustrate that the AR-CM NCTF controller shows the higher motion performances the higher robustness to plant parameter variations than the PDDO controllers
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