A NOTE ON THE COMPUTATION OF THE BAYESIAN DECOMPOSITION OF A TIME SERIES

Abstract. The purpose of the present note is to propose an efficient algorithm for the Bayesian decomposition of a time series, utilizing some results recently developed in the area of methods of regularization of certain integral equations. Within this framework, it is shown how the special structure of the problem can be exploited so that a considerable gain in computational efficiency over existing procedures can be obtained.     

The ubiquitous provisioning of internet services to portable devices

Advances in mobile telecommunications and device miniaturization call for providing both standard and novel location- and context-dependent Internet services to mobile clients. Mobile agents are dynamic, asynchronous, and autonomous, making the MA programming paradigm suitable for developing novel middleware for mobility-enabled services.     

DARGOS: A highly adaptable and scalable monitoring architecture for multi-tenant Clouds

One of the most important features in Cloud environments is to know the status and the availability of the physical resources and services present in the current infrastructure. A full knowledge and control of the current status of those resources enables Cloud administrators to design better Cloud provisioning strategies and to avoid SLA violations. However, it is not easy to manage such information in a reliable and scalable way, especially when we consider Cloud environments used and shared by several tenants and when we need to harmonize their different monitoring needs at different Cloud software stack layers. To cope with these issues, we propose Distributed Architecture for Resource manaGement and mOnitoring in cloudS (DARGOS), a completely distributed and highly efficient Cloud monitoring architecture to disseminate resource monitoring information. DARGOS ensures an accurate measurement of physical and virtual resources in the Cloud keeping at the same time a low overhead. In addition, DARGOS is flexible and adaptable and allows defining and monitoring new metrics easily. The proposed monitoring architecture and related tools have been integrated into a real Cloud deployment based on the OpenStack platform: they are openly available for the research community and include a Web-based customizable Cloud monitoring console. We report experimental results to assess our architecture and quantitatively compare it with a selection of other Cloud monitoring systems similar to ours showing that DARGOS introduces a very limited and scalable monitoring overhead.     

A quasi-Newton method for unconstrained non-smooth problems

We present a method, based on a variational problem, for solving a non-smooth unconstrained optimization problem. We assume that the objective function is a Lipschitz continuous and a regular function. In this case the function of our variational problem is semismooth and a quasi-Newton method may be used to solve the variational problem. A convergence theorem for our algorithm and its discrete version is also proved. Preliminary computational results show that the method performs quite well and can compete with other methods.     

On the microstructure and magnetization process of γ-Fe2O3

Experimental evidence is reported for γ-Fe2O3single particles being made up of several microcrystals chained together and their boundaries being sources of demagnetizing fields. This leads to a very defined picture of the magnetization reversal in partially alligned γ-Fe2O3particles: rotation is incoherent but the magnetization vectors are scattered in such a way that Hcivs. angle Ψ (between the orientation direction and the applied field) does not follow the known magnetization reversal modes. The importance of the reduction temperature in the process: α-FeOOHunderrightarrow{red.}Fe3O4underrightarrow{ox.}γ-Fe2O3becomes extremely important if considered as the parameter which rules the pore closure within the particles, i.e. the size and number of microcrystals chained in a single particle.     

The effect of pozzolanas on the tricalcium aluminate hydration

The effect of pozzolanas on the C₃A hydration with and without lime and gypsum was examined. The addition of pozzolana lowers the heat evolution caused by C₃A hydration. Lime combination with C₃A and its hydration product is favoured by the addition of pozzolana, with a different mechanism of reaction depending on the presence of gypsum. Volcanic pozzolana in the presence of lime accelerates the transformation from hexagonal hydroaluminate to cubic C₃AH₆.     

Context-aware middleware for resource management in the wireless Internet

The provisioning of Web services over the wireless Internet introduces novel challenging issues for service design and implementation: from user/terminal mobility during service execution, to wide heterogeneity of portable access devices and unpredictable modifications in accessible resources. In this scenario, there are frequent provision-time changes in the context, defined as the logical set of accessible resources depending on client location, access terminal capabilities, and system/service management policies. The development of context-dependent services requires novel middlewares with full context visibility. We propose a middleware for context-aware resource management, called CARMEN, capable of supporting the automatic reconfiguration of wireless Internet services in response to context changes without any intervention on the service logic. CARMEN determines the context on the basis of metadata, which include declarative management policies and profiles for user preferences, terminal capabilities, and resource characteristics. In addition, CARMEN exploits the mobile agent technology to implement mobile middleware components that follow the provision-time movement of clients to support locally their customized service access. The proposed middleware shows how metadata and mobile agents can favor component reusability and automatic service reconfiguration, by reducing the development/ deployment complexity.     

Specification Tests for the Variance of a Diffusion

We propose specification tests for the variance of a diffusion that do not require complete knowledge of the functional form under the null. We first propose a test for the constancy of the variance that, under the null of constancy, has a limiting normal distribution, while under the alternative of either unconditional or conditional heteroskedasticity it diverges at an appropriate rate. We then propose a test for the null of a parametric specification against the alternative of a more general functional form. Under the null, the test has a well-defined limiting distribution, normal in the unconditional and mixed normal in the conditional heteroskedasticity case; under the alternative, it diverges.     

Round Robin Test for composite-to-brick shear bond characterization

The paper presents the experience of a working group within the RILEM Technical Committee 223-MSC ??Masonry Strengthening with Composite materials??, aimed at developing a standardized, reliable procedure for characterizing the bonding mechanism of masonry elements strengthened with composite materials under shear actions. Twelve laboratories from European universities and research centers were involved. Two different set-ups were compared, for single-lap and double-lap shear tests (the latter in two versions). Four kinds of fiber fabrics, i.e., glass, carbon, basalt and steel, were applied with epoxy resins (wet lay-up system) to clay brick units, for a total of 280 monotonic tests. The results provided information regarding the response of externally bonded-to-brick composites in terms of observed failure mechanisms, load capacity, effective transfer length, and bond shear stress?Cslip behavior. The test results of the 12 laboratories constitute a set of statistically representative data which may conveniently be used for setting appropriate design provisions and guidelines.     

Shear behavior of unreinforced and reinforced masonry panels subjected to in situ diagonal compression tests

Approach to safety evaluations issued by modern codes is clearly based on quantitative assessment of performances. As a consequence, validated mechanical parameters and numerical models should be made available on large scale for practical applications. This is the background of the present paper that deals with a specific type of masonry largely used in Central Italy and particularly in Umbria and Abruzzo region, whose territory exhibits a relevant seismic risk. A research project focused on the shear behavior of masonry panels subjected to in situ diagonal compression tests has been issued. The project consists of two parts: tests were performed on unreinforced and reinforced panels. As to the unreinforced panels, focusing attention on the diagonal cracking failure mode, the experimental research allowed to provide representative values of the mechanical parameters adopted to define the limit strength domain of some typical masonry walls in old buildings of Umbria and Abruzzo. Conversely, reinforced panels were tested aimed at investigating the effectiveness of existing methods of repair. A comparison between traditional and innovative seismic-upgrading techniques has been made in order to characterize the behavior of historical masonry walls under different strengthening configurations.