Generating Erler-Schnabl-type Solution for Tachyon Vacuum in Cubic Superstring Field Theory

We study a new set of identity-based solutions to analyze the problem of tachyon condensation in open bosonic string field theory and cubic superstring field theory. Even though these identity-based solutions seem to be trivial, it turns out that after performing a suitable gauge transformation, we are left with the known Erler-Schnabl-type solutions which correctly reproduce the value of the D-brane tension. This result shows explicitly that how a seemingly trivial solution can generate a non-trivial configuration which precisely represents to the tachyon vacuum.Comment: 22 pages, references added, appendix added, 2 subsections adde

Sobre la existencia del producto de medidas valoradas en espacios localmente convexos : una condición necesaria

A necessary condition is given for the existente of the tensor product of certain measures valued in locally convex spaces

Comments on regularization of identity based solutions in string field theory

We analyze the consistency of the recently proposed regularization of an identity based solution in open bosonic string field theory. We show that the equation of motion is satisfied when it is contracted with the regularized solution itself. Additionally, we propose a similar regularization of an identity based solution in the modified cubic superstring field theory.Comment: 24 pages, two subsections added, two references adde

Learn-ciam: a model-driven approach for the development of collaborative learning tools

This paper introduces Learn-CIAM, a new model-based methodological approach for the design of flows and for the semi-automatic generation of tools in order to support collaborative learning tasks. The main objective of this work is to help professors by establishing a series of steps for the specification of their learning courses and the obtaining of collaborative tools to support certain learning activities (in particular, for in-group editing, searching and modeling). This paper presents a complete methodological framework, how it is supported conceptually and technologically, and an application example. So to guarantee the validity of the proposal, we also present some validation processes with potential designers and users from different profiles such as Education and Computer Science. The results seem to demonstrate a positive reception and acceptance, concluding that its application would facilitate the design of learning courses and the generation of collaborative learning tools for professionals of both profiles

Rectified Output Power Analysis of Piezoelectric Energy Harvester Arrays under Noisy Excitation

In the past decade, vibration energy harvesting has emerged as a potential alternative solution to power wireless sensor nodes. In real-world implementations, external excitation can be very noisy and includes noise signals in a wide frequency band. In order to accommodate operation under noisy excitation, arrays of energy harvesters with different resonance frequencies are often employed to improve responsibility. Due to the nature of noisy excitation and the difference in resonance frequencies, the response voltage signals from each harvester can be very different in amplitude, frequency and phase. In this paper, an array with two cantilevered energy harvesters is studied to analyze the rectified output power with different configurations using full-bridge rectifiers (FBR). The experiments show that connecting the two harvesters in parallel or in series before connecting with a FBR results in significant voltage cancellation due to phase mismatch. The most efficient way to extract energy is to use two FBRs for the two cantilevered energy harvesters, individually, and charge to one single storage capacitor connected at the outputs of the two FBRs

Amorphous Metallic Glass as New High Power and Energy Density Anodes For Lithium Ion Rechargeable Batteries

We have investigated the use of aluminum based amorphous metallic glass as the anode in lithium ion rechargeable batteries. Amorphous metallic glasses have no long-range ordered microstructure; the atoms are less closely packed compared to the crystalline alloys of the same compositions; they usually have higher ionic conductivity than crystalline materials, which make rapid lithium diffusion possible. Many metallic systems have higher theoretical capacity for lithium than graphite/carbon; in addition irreversible capacity loss can be avoided in metallic systems. With careful processing, we are able to obtain nano-crystalline phases dispersed in the amorphous metallic glass matrix. These crystalline regions may form the active centers with which lithium reacts. The surrounding matrix can respond very well to the volume changes as these nano-size regions take up lithium. A comparison study of various kinds of anode materials for lithium rechargeable batteries is carried out.Singapore-MIT Alliance (SMA

On Gauge Equivalence of Tachyon Solutions in Cubic Neveu-Schwarz String Field Theory

Simple analytic solution to cubic Neveu-Schwarz String Field Theory including the $GSO(-)$ sector is presented. This solution is an analog of the Erler-Schnabl solution for bosonic case and one of the authors solution for the pure $GSO(+)$ case. Gauge transformations of the new solution to others known solutions for the $NS$ string tachyon condensation are constructed explicitly. This gauge equivalence manifestly supports the early observed fact that these solutions have the same value of the action density.Comment: 8 pages, LaTe

High temperature performance of a piezoelectric micro cantilever for vibration energy harvesting

Energy harvesters withstanding high temperatures could provide potentially unlimited energy to sensor nodes placed in harsh environments, where manual maintenance is difficult and costly. Experimental results on a classical microcantilever show a 67% drop of the maximum power when the temperature is increased up to 160 °C. This decrease is investigated using a lumped-parameters model which takes into account variations in material parameters with temperature, damping increase and thermal stresses induced by mismatched thermal coefficients in a composite cantilever. The model allows a description of the maximum power evolution as a function of temperature and input acceleration. Simulation results further show that an increase in damping and the apparition of thermal stresses are contributing to the power drop at 59% and 13% respectively