88 research outputs found
Supersymmetric reduced models with a symmetry based on Filippov algebra
Generalizations of the reduced model of super Yang-Mills theory obtained by
replacing the Lie algebra structure to Filippov -algebra structures are
studied. Conditions for the reduced model actions to be supersymmetric are
examined. These models are related with what we call \{cal N}_{min}=2 super
-brane actions.Comment: v3: In the previous versions we overlooked that Eq.(3.9) holds more
generally, and missed some supersymmetric actions. Those are now included and
modifications including a slight change in the title were made accordingly.
1+18 page
Three-algebra for supermembrane and two-algebra for superstring
While string or Yang-Mills theories are based on Lie algebra or two-algebra
structure, recent studies indicate that M-theory may require a one higher,
three-algebra structure. Here we construct a covariant action for a
supermembrane in eleven dimensions, which is invariant under global
supersymmetry, local fermionic symmetry and worldvolume diffeomorphism. Our
action is classically on-shell equivalent to the celebrated
Bergshoeff-Sezgin-Townsend action. However, the novelty is that we spell the
action genuinely in terms of Nambu three-brackets: All the derivatives appear
through Nambu brackets and hence it manifests the three-algebra structure.
Further the double dimensional reduction of our action gives straightforwardly
to a type IIA string action featuring two-algebra. Applying the same method, we
also construct a covariant action for type IIB superstring, leading directly to
the IKKT matrix model.Comment: 1+15 pages, no figure; Refs added, Accepted for publication in JHE
Taking off the square root of Nambu-Goto action and obtaining Filippov-Lie algebra gauge theory action
We propose a novel prescription to take off the square root of Nambu-Goto
action for a p-brane, which generalizes the Brink-Di Vecchia-Howe-Tucker or
also known as Polyakov method. With an arbitrary decomposition as d+n=p+1, our
resulting action is a modified d-dimensional Polyakov action which is gauged
and possesses a Nambu n-bracket squared potential. We first spell out how the
(p+1)-dimensional diffeomorphism is realized in the lower dimensional action.
Then we discuss a possible gauge fixing of it to a direct product of
-dimensional diffeomorphism and n-dimensional volume preserving
diffeomorphism. We show that the latter naturally leads to a novel Filippov-Lie
n-algebra based gauge theory action in d-dimensions.Comment: 1+13 pages, No figure; Expanded, published version. Title change
Water-soluble biowaste gum binders for natural graphite anode for lithium-ion batteries
Anode materials for lithium-ion batteries (LIBs) are crucial, as lithium insertion takes place in the anode during the charging process. Also, it is rational to replace the conventional polyvinylidene fluoride (PVdF) with a water-soluble binder because the former employs N-Methyl-2-pyrrolidone, which is environmentally harmful. To address the problem, we fabricated natural graphite (NG)-based anodes with water-soluble biowaste (W-SB) binders from the gum of the tree Cochlospermum gossypium and PVdF. Both of the electrodes were fabricated using 10 wt% of binder and were evaluated for their electrochemical performance. The NG-W-SB electrode showed good mechanical properties and maintained structural integrity after cycling, this promoted low charge transfer resistance on the electrode. NG-W-SB-based electrode showed high current peaks in the 1st cycle being an indication of enhanced electrochemical performance, unlike the NG-PVdF electrode which showed slightly low peaks. NG-W-SB maintained a higher stable capacity retention up to 360 cycles, whereas NG-PVdF had a capacity degradation after 200 cycles indicating a low capacity retention until the end of the cycle. Generally, W-SB binders showed highly enhanced cycling retention characteristics, comparable rate capabilities, and lower electrode resistance, which opened a new avenue for adopting biowaste (gum) as a functional water-soluble binder for LIBs applications
Comparison stripmap COSMOS SkyMed X-band and tops Sentinel-1 C-band in estimating ground subsidence using irstea TOMOSAR platform: Ho Chi Minh City case study
International audienceThe objective of this paper is to provide a better understanding of Persistent Scatterers Interferometry (PSI) capabilities in subsidence estimations of TOPSAR Sentinel-1 data. This work has presented an advanced PSI analysis, to provide unprecedented spatial extent and continuous temporal coverage of the subsidence in Ho Chi Minh City by using 49 stripmap Cosmos SkyMED (CSK) X-band and TOPS Sentinel-1 Cband 23 images acquired from 2014 to 2016. The analysis was carried out by using the Irstea TomoSAR platform, which supports the entire processing from SAR, Interferometry, Polarimetry, to Tomography (so called TomoSAR). The study shows that the performance of stripmap CSK and TOPS Sentinel-1 is quite similar and effective to detect the subsidence phenomena. Subsidence is most severe in the Holocene silt loam areas along Sai Gon river and in the Southwest of the city, with the maximum value up to-30 mm/yr, similar with the previous study using ALOS PALSAR. Index Terms-Synthetic Aperture Radar, TOPS Sentinel-1, Comos SkyMED, TomoSAR platform, service as demand, subsidence, Ho Chi Minh City, Vietnam
THE EXTRACURRICULAR CLASSES ORGANIZED THROUGH VOLUNTARY WORKS IN THE MOUNTAINOUS REGIONS FOR THE MEDIA STUDENT
The author of the present paper studies the scale and the outcomes of organizing the extracurricular classes through voluntary works in the mountain areas by evaluating the survey of participants' notion. This paper has 3 important categories: this article takes the reasons of choosing Vietnam's mountainous regions are in accord with voluntary activities into consideration, indicating the tasks and the process of carrying out extracurricular classes for students at faculty of the Multimedia Communication in Thang Long University. This paper aims to display an extracurricular learning model which is possible to carry out regularly for students in journalism and media in general. The purposes of this research do not only benefit the students but also the professor, lecturer and the whole educator because the significance of this work is that: the first is to engage students in their majors then helps them to apply their learned skills in practice, as well as contributes to renewing the traditional education at Vietnamese Universities
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