Nontrivial temporal scaling in a Galilean stick-slip dynamics

We examine the stick-slip fluctuating response of a rough massive non-rotating cylinder moving on a rough inclined groove which is submitted to weak external perturbations and which is maintained well below the angle of repose. The experiments presented here, which are reminiscent of the Galileo's works with rolling objects on inclines, have brought in the last years important new insights into the friction between surfaces in relative motion and are of relevance for earthquakes, differing from classical block-spring models by the mechanism of energy input in the system. Robust nontrivial temporal scaling laws appearing in the dynamics of this system are reported, and it is shown that the time-support where dissipation occurs approaches a statistical fractal set with a fixed value of dimension. The distribution of periods of inactivity in the intermittent motion of the cylinder is also studied and found to be closely related to the lacunarity of a random version of the classic triadic Cantor set on the line.Comment: 7 pages including 6 figure

Eigenvalue analysis for plain-woven fabric structure using shell element and one smoothing cell in the smoothed finite element method

An efficient four-node quadrilateral (Q4) shell element based on the first-order shear deformation theory of plate (FSDT) and the strain smoothing technique in finite elements (referred as SFEM) was proposed for eigenvalue analysis of plain-woven fabric structure. A one smoothing domain (or cell) integration scheme in SFEM was proposed to evaluate the nodal train fields of Q4 shell elements. The numerical result of eigenvalue analysis, which was in the case of free vibration analysis, approximated to that one implemented in the finite element method (FEM) but gave a higher efficiency in computation in terms of central processing unit (CPU) time and numerical implementation.The authors wish to express their acknowledgment to FCT funding from FCT – Foundation for Science and Technology within the scope of the project “PEST UID/CTM/00264; POCI-01-0145-FEDER 007136

Buckling analysis of plain-woven fabric structure using shell element and a one cell-based integration scheme in smoothed finite element method

A one smoothing cell integration scheme in the strain smoothing technique in finite elements (referred as SFEM) was proposed to evaluate the nodal train fields of a four-node quadrilateral (Q4) shell element, which is based on the first-order shear deformation theory of plate (FSDT). A mixed interpolation of tensorial components (MITC) approaches for Q4 transverse shear strains also applied to eliminate a shear locking phenomenon that may occur when the thin plate/shell elements are geometrically distorted in curved geometries of fabric sheet. The numerical eigenvalues of buckling analysis of a plain-woven fabric sample, of which physical and mechanical parameters extracted from Kawabata evaluation system for fabrics (KES-FB), obtained a higher efficiency in numerical computation and approximated to Q4 shell element implemented in the finite element method (FEM).The authors wish to express their acknowledgment to FCT funding from FCT – Foundation for Science and Technology within the scope of the project “PEST UID/CTM/00264; POCI-01-0145-FEDER 007136”

Using the post‐operative quality recovery scale to evaluate recovery with different neuromuscular blocking reversal agentsin the Portuguese population ‐ interim analysis results: 1AP3‐8

Background and Goal of Study: Post-operative Quality Recovery Scale (PQRS), is the first scale evaluating several domains of postoperative recovery. The objectives of this study were to compare overal and physiologic, cognitive, and functional domains of post-operative recovery af ter elective surgical procedures using neostigmine or sugammadex as neuromuscular blocking (NMB) reversal agents, to validate the use of PQRS in the Portuguese population and to objectively assess muscular strength recovery. Materials and Methods: Prospective multicenter observational study comparing postoperative recovery between 2 cohorts of 50 adult patients submitted to elective surgical procedures with general anesthesia using Nondepolarizing Muscle Relaxants and NMB reversal with neostigmine or sugammadex. Measurements obtained using Portuguese version of PQRS at dif ferent timepoint: baseline,15 minutes (T15), 40 minutes (T40), one and three days af ter surgery. Full recovery defined as return to values identical or higher than those measured at baseline, prior to surgery. Muscular strength measured with KERN- MAP® Dynamometer. Ethics Committees approval was obtained. Statistics used linear T-Test, Qui Square and Fisher exact test, data presented as mean±SD for continuous variables. Interim analysis results presented Results and Discussion: Thirty patients received neostigmine and 21 sugammadex. Age and BMI 50.4±11.8 and 28.6±5.6 in the neostigmine group and 38.2±12.7 and 24.7± 4.5 in the sugammadex group (p< 0,001). Overall response rate at T15 was 86% for neostigmine and 95% for sugammadex (p= 0.22). Dif ferences in favor of sugammadex group noted in nociceptive and emotional domains, 80 vs 100% respectively (p=0.04). Overall response rate at T40 was 80% for neostigmine and 65% for sugammadex (p=0.33), primarily reflecting constraints on activities of daily life. Muscular strength did not dif fer. Improvements in recovery scores from T15 to T40 were observed in both groups, without significant dif ferences . Postoperative assessments were feasible using PQRS at T15 and T40 and seem appropriate for comparisons between postoperative recovery domains and overall recovery . These preliminary results suggest nociceptive and emotional domains recovery at T15 may be faster with sugammadex. Conclusion: The results support the adopted PQRS validation process and the potential of this scale as a tool for the evaluation of post operative recovery evaluation in the Portuguese populatio

Quebra de dormência de sementes de pequi (Caryocar coriaceum Wittm.).

O fruto do pequizeiro possui grande aceitação na culinária regional, sendo consumido com arroz, frango, feijão, podendo ser usado também na fabricação de licor, sorvetes e picolés (VERA, 2004). Contudo, sua exploração ocorre de forma totalmente extrativista (OLIVEIRA, 2009), tornando esta atividade de grande importância socioeconômica, gerando renda e emprego à população do cerrado. O objetivo deste trabalho foi avaliar tratamentos de quebra de dormência de sementes de pequi

Non Abelian Sugawara Construction and the q-deformed N=2 Superconformal Algebra

The construction of a q-deformed N=2 superconformal algebra is proposed in terms of level 1 currents of ${\cal{U}}_{q} ({\widehat{su}}(2))$ quantum affine Lie algebra and a single real Fermi field. In particular, it suggests the expression for the q-deformed Energy-Momentum tensor in the Sugawara form. Its constituents generate two isomorphic quadratic algebraic structures. The generalization to ${\cal{U}}_{q} ({\widehat{su}}(N+1))$ is also proposed.Comment: AMSLATEX, 21page

(Broken) Gauge Symmetries and Constraints in Regge Calculus

We will examine the issue of diffeomorphism symmetry in simplicial models of (quantum) gravity, in particular for Regge calculus. We find that for a solution with curvature there do not exist exact gauge symmetries on the discrete level. Furthermore we derive a canonical formulation that exactly matches the dynamics and hence symmetries of the covariant picture. In this canonical formulation broken symmetries lead to the replacements of constraints by so--called pseudo constraints. These considerations should be taken into account in attempts to connect spin foam models, based on the Regge action, with canonical loop quantum gravity, which aims at implementing proper constraints. We will argue that the long standing problem of finding a consistent constraint algebra for discretized gravity theories is equivalent to the problem of finding an action with exact diffeomorphism symmetries. Finally we will analyze different limits in which the pseudo constraints might turn into proper constraints. This could be helpful to infer alternative discretization schemes in which the symmetries are not broken.Comment: 32 pages, 15 figure

Agent-based homeostatic control for green energy in the smart grid

With dwindling non-renewable energy reserves and the adverse effects of climate change, the development of the smart electricity grid is seen as key to solving global energy security issues and to reducing carbon emissions. In this respect, there is a growing need to integrate renewable (or green) energy sources in the grid. However, the intermittency of these energy sources requires that demand must also be made more responsive to changes in supply, and a number of smart grid technologies are being developed, such as high-capacity batteries and smart meters for the home, to enable consumers to be more responsive to conditions on the grid in real-time. Traditional solutions based on these technologies, however, tend to ignore the fact that individual consumers will behave in such a way that best satisfies their own preferences to use or store energy (as opposed to that of the supplier or the grid operator). Hence, in practice, it is unclear how these solutions will cope with large numbers of consumers using their devices in this way. Against this background, in this paper, we develop novel control mechanisms based on the use of autonomous agents to better incorporate consumer preferences in managing demand. These agents, residing on consumers' smart meters, can both communicate with the grid and optimise their owner's energy consumption to satisfy their preferences. More specifically, we provide a novel control mechanism that models and controls a system comprising of a green energy supplier operating within the grid and a number of individual homes (each possibly owning a storage device). This control mechanism is based on the concept of homeostasis whereby control signals are sent to individual components of a system, based on their continuous feedback, in order to change their state so that the system may reach a stable equilibrium. Thus, we define a new carbon-based pricing mechanism for this green energy supplier that takes advantage of carbon-intensity signals available on the internet in order to provide real-time pricing. The pricing scheme is designed in such a way that it can be readily implemented using existing communication technologies and is easily understandable by consumers. Building upon this, we develop new control signals that the supplier can use to incentivise agents to shift demand (using their storage device) to times when green energy is available. Moreover, we show how these signals can be adapted according to changes in supply and to various degrees of penetration of storage in the system. We empirically evaluate our system and show that, when all homes are equipped with storage devices, the supplier can significantly reduce its reliance on other carbon-emitting power sources to cater for its own shortfalls. By so doing, the supplier reduces the carbon emission of the system by up to 25% while the consumer reduces its costs by up to 14.5%. Finally, we demonstrate that our homeostatic control mechanism is not sensitive to small prediction errors and the supplier is incentivised to accurately predict its green production to minimise costs