Polytechnic University of Milan

About: Polytechnic University of Milan is a education organization based out in Milan, Italy. It is known for research contribution in the topics: Computer science & Finite element method. The organization has 18231 authors who have published 58416 publications receiving 1229711 citations. The organization is also known as: PoliMi & L-NESS.

Camera as the instrument: the rising trend of vision based measurement

Abstract: Due to continuing and rapid advances of both hardware and software technologies in camera and computing systems, we continue to have access to cheaper, faster, higher quality, and smaller cameras and computing units. As a result, vision based methods consisting of image processing and computational intelligence can be implemented more easily and affordably than ever using a camera and its associated operations units. Among their various applications, such systems are also being used more and more by researchers and practitioners as generic instruments to measure and monitor physical phenomena. In this article, we take a look at this rising trend and how cameras and vision are being used for instrumentation and measurement, and we also cast a glance at the metrological gauntlet thrown down by vision-based instruments.

Charge order and its connection with Fermi-liquid charge transport in a pristine high- T c cuprate

Abstract: Electronic inhomogeneity appears to be an inherent characteristic of the enigmatic cuprate superconductors. Here we report the observation of charge-density-wave correlations in the model cuprate superconductor HgBa2CuO(4+δ) (T(c)=72 K) via bulk Cu L3-edge-resonant X-ray scattering. At the measured hole-doping level, both the short-range charge modulations and Fermi-liquid transport appear below the same temperature of about 200 K. Our result points to a unifying picture in which these two phenomena are preceded at the higher pseudogap temperature by q=0 magnetic order and the build-up of significant dynamic antiferromagnetic correlations. The magnitude of the charge modulation wave vector is consistent with the size of the electron pocket implied by quantum oscillation and Hall effect measurements for HgBa2CuO(4+δ) and with corresponding results for YBa2Cu3O(6+δ), which indicates that charge-density-wave correlations are universally responsible for the low-temperature quantum oscillation phenomenon.

Excitability of the soleus H-reflex arc during walking and stepping in man

Abstract: In eight normal subjects, the excitability of the soleus (Sol) H-reflex was tested in parallel with Sol length changes, EMGs of leg and thigh muscles and ground contact phases, during three different pacing movements: bipedal treadmill walking, single limb treadmill walking, and single-limb stepping on one spot. A computerized procedure was used which compensated for changes in stimulus effectiveness that occurred during free motion. In the three paradigms examined, significant excitability modulations were observed with respect to a control level determined in standing weight-bearing position. During bipedal treadmill walking, excitability was decreased in the early stance, maximally enhanced in the second half of the stance, and again decreased during the end-stance and the whole swing phase, with a minimum value around the toe off period. The main modulation pattern was retained during single-limb treadmill walking. During single-limb stepping on one spot, the stance-phase increase in excitability and the swing phase depression were still present. However, in the second half of the swing phase, reflex responsiveness returned to reference level, which was maintained during the subsequent contact period. Moreover, a decrease in reflex excitability was detected around the mid-stance. The time course of the described modulations was only partly correlated with the EMG and length changes of the Sol muscle. Furthermore, in the three movements tested, during the early stance phase, the excitability of the H-reflex arc did not correspond to the one expected on the basis of the available H-reflex studies performed under static conditions. It is suggested that, at least in certain stride phases (e.g. around the early contact period), an active regulation affects the transmission in the Sol myotatic arc during the pacing movements investigated.

Model evolution by run-time parameter adaptation

Abstract: Models can help software engineers to reason about design-time decisions before implementing a system. This paper focuses on models that deal with non-functional properties, such as reliability and performance. To build such models, one must rely on numerical estimates of various parameters provided by domain experts or extracted by other similar systems. Unfortunately, estimates are seldom correct. In addition, in dynamic environments, the value of parameters may change over time. We discuss an approach that addresses these issues by keeping models alive at run time and feeding a Bayesian estimator with data collected from the running system, which produces updated parameters. The updated model provides an increasingly better representation of the system. By analyzing the updated model at run time, it is possible to detect or predict if a desired property is, or will be, violated by the running implementation. Requirement violations may trigger automatic reconfigurations or recovery actions aimed at guaranteeing the desired goals. We illustrate a working framework supporting our methodology and apply it to an example in which a Web service orchestrated composition is modeled through a Discrete Time Markov Chain. Numerical simulations show the effectiveness of the approach.

LIME: A coordination model and middleware supporting mobility of hosts and agents

Abstract: LIME (Linda in a mobile environment) is a model and middleware supporting the development of applications that exhibit the physical mobility of hosts, logical mobility of agents, or both. LIME adopts a coordination perspective inspired by work on the Linda model. The context for computation, represented in Linda by a globally accessible persistent tuple space, is refined in LIME to transient sharing of the identically named tuple spaces carried by individual mobile units. Tuple spaces are also extended with a notion of location and programs are given the ability to react to specified states. The resulting model provides a minimalist set of abstractions that facilitates the rapid and dependable development of mobile applications. In this article we illustrate the model underlying LIME, provide a formal semantic characterization for the operations it makes available to the application developer, present its current design and implementation, and discuss lessons learned in developing applications that involve physical mobility.