Two fast architectures for the direct 2-D discrete wavelettransform

We propose two architectures for the direct two-dimensional (2-D) discrete wavelet transform (DWT). The first one is based on a modified recursive pyramid algorithm (MRPA) and performs a “"nonstandard” decomposition (i.e., Mallat's (1989) tree) of an N×N image in approximately 2N²/3 clock cycles (ccs). This result consistently speeds up other known architectures that commonly need approximately N² ccs. Furthermore, the proposed architecture is simpler than others in terms of hardware complexity. Subsequently, we show how “symmetric”/“anti-symmetric” properties of linear-phase wavelet filter bases can be exploited in order to further reduce the VLSI area. This is used to design a second architecture that provides one processing unit for each level of decomposition (pipelined approach) and performs a decomposition in approximately N²/2 ccs. In many practical cases, even this architecture is simpler than general MRPA-based devices (having only one processing unit)     

On vanishing stability regions in nonlinear systems with high-gain feedback

When local stabilization of nonlinear systems is achieved by linear feedback, the resulting stability region may vanish as the feedback gains increase. This is demonstrated by examples in which neglected nonlinearities create an unstable limit cycle around an asymptotically stable equilibrium. As the feedback gains tend to infinity the unstable limit cycle shrinks to the equilibrium. If a feedback linearization design is applied, the same instability mechanism may occur when the nonlinearities are not precisely known.     

Effect of different ventilation regimens on ewes' milk and Canestrato Pugliese cheese quality in summer

The influence of three different ventilation regimens on air pollution in sheep houses and on the quality of ewe milk and of Canestrato Pugliese cheese was investigated during the summer season. The experimental treatments were low ventilation regimen (VR=35 m3/h per ewe) split in 30-min ventilation cycles (LOV-30); moderate ventilation regimen (VR=70 m3/h per ewe) split in 30-min ventilation cycles (MOV-30); moderate ventilation regimen (VR=70 m3/h per ewe) split in 60-min ventilation cycles (MOV-60). The LOV-30 milk had higher microbial load and bulk milk somatic cell count (BMSCC) and resulted in a weaker casein matrix in the curd compared with the MOV-30 and MOV-60 treatments. At 45 d of ripening, the LOV-30 cheeses had a lower casein content and higher non-casein nitrogen (NCN) and water-soluble nitrogen (WSN) contents than the MOV-30 and MOV-60 cheeses. Urea-polyacrylamide gel electrophoresis (urea-PAGE) of the pH 4.6-soluble N extract showed that the MOV-60 cheeses had fewer bands derived from casein (CN) hydrolysis than the LOV-30 or MOV-30 cheeses, despite its having exhibited the highest plasmin (PL) activity levels. Our results suggest that the ventilation regimen is critical in dairy sheep housing for optimizing the hygienic quality of ewe milk and the proteolytic processes occurring in Canestrato Pugliese cheese during ripening.     

Effect of microstructure on thermal expansion behaviour of nanocrystalline metallic materials

Materials properties, among which thermodynamic ones, are influenced by microstructural features. This is so also in the case of nanocrystalline materials, featuring average grain size below 100 nm. A reduced grain size involves that significant fractions of atoms are localised in grain boundary regions and this has remarkable effects on the resulting thermodynamic properties, like heat capacity, transition temperatures, coefficient of thermal expansion, etc. In the present work we consider the thermal expansion behaviour of ball-milled nanocrystalline metallic powders using dilatometric measurements. High-energy ball-milling, that is capable to achieve extremely high deformation degrees, induces in the milled powders microstructural defects, like vacancies, antisites, dislocations and planar faults. Another effect of milling is the reduction of the crystallite size, that, in the long run, may reach the nanometric range. In view of the microstructural changes that can be brought about by milling and of the numerous transformations occurring during the dilatometric runs, a comparative study has been conducted on intermetallic, NiAl and Ni₃Al, and on a pure metal, nickel, powders. The results emerging from the experimental investigation are quite complex, owing to the complex defect structures that are present in the ball-milled powders. It turns out that the thermal expansion coefficient of the nanocrystalline powders increases as the average grain size is reduced. However, when the average grain size achieves very low values, the strain relaxation of the crystalline lattice and the rearrangement of grain boundary regions result in a reduction of the thermal expansion coefficient. Another aspect that emerges from the dilatometric curves is the interplay between recrystallization and reordering, i.e. the re-establishment of the long-range order in the intermetallic powders, that had been partially or fully eliminated by ball-milling.     

An accurate calculation model of solar heat gain through glazed surfaces

A model for the calculation of solar heat gain through glazed surfaces, to be used in the simplified calculation of thermal energy requirements in air-conditioned buildings, is proposed. The model uses the effective absorption coefficient of the indoor environment to take into account that the entering energy is in part absorbed by the surfaces of the cavity and in part is dispersed outwards, through the same glazed surfaces. The effective absorption coefficient is calculated by means of a correlation, and is made to depend on the average absorption coefficient of the internal opaque surfaces of the environment, on the glazed fraction and on the transmission coefficient of diffuse radiation of the glazed system. This coefficient permits a more accurate evaluation of solar heat gain through glazed surfaces, obtained adding: the direct optical contribution, produced by solar radiation absorbed by the indoor environment, the direct secondary contribution, produced by external solar radiation absorbed by the glazed surfaces, the indirect secondary contribution, produced by the absorption of reflected radiation exiting the indoor environment. The model, validated by means of comparisons with the TRNSYS 16 code, was used for the verification of the monthly solar heat gain calculation procedure of EN ISO 13790:2008.     

The Effect of Surface Stresses on the Critical Debonding Stress Around Nanoparticles

With the aid of an energy analysis and the surface elasticity theory, this work provides a closed form solution for the critical debonding stress of a rigid nanoparticle embedded in an elastic matrix subjected to a remote hydrostatic stress. It is proved that the debonding stress depends on the particle radius, the matrix elastic properties and the fracture energy per unit surface. The solution allows quantifying the effects of surface elastic constants, also showing that the smaller the particle size the more significant those effects are.     

A decentralized kinematic control architecture for collaborative and cooperative multi-arm systems

In this paper a two-layer decentralized framework for kinematic control of cooperative and collaborative multi-robot systems is developed. The motion of the system is specified at the workpiece level, by adopting a task-oriented formulation for cooperative tasks. The first layer computes the motion of the single arms in the system. In detail, the control unit of each robot computes the end-effector motion references in a decentralized fashion on the basis of the knowledge of the assigned cooperative task and the motion references computed by its neighbors. Then, in the second layer, each control unit computes the reference joint motion of the corresponding manipulator from the end-effector reference motion. The approach is, then, tested in simulation on a work-cell composed by several manipulators, and experimentally on a dual-arm kinematically redundant work-cell composed by industrial manipulators.     

Essentialism revisited: Evolutionary theory and the concept of mental disorder.

J. C. Wakefield's (1999) elaboration of his harmful dysfunction analysis (HDA) of mental disorder does little to address previous criticisms (S. O. Lilienfeld & L. Marino, 1995) and instead reveals further conceptual weaknesses in his position. The authors demonstrate that (a) a Roschian analysis can account for the results of all of Wakefield's conceptual experiments and predicts a number of judgments of disorder not predicted by the HDA, (b) the HDA is incapable in many cases of providing a scientifically nonarbitrary distinction between disorder and nondisorder, and (c) the HDA cannot account for failures of cultural exaptations, mismatches between evolutionary design and novel environments, or defenses against threat. The authors argue that the HDA has been convincingly falsified and discuss the failure of essentialistic concepts to resolve controversies in other domains of biological science. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On fault-tolerant observers

The problem of designing asymptotic observers for multioutput systems with one unreliable output measurement is addressed. It is shown that observers designed on the basis of observability indexes are not fault tolerant, and an observer for linear systems which tolerates failures in one a priori known output is given. The results are extended to nonlinear systems with no inputs: it is pointed out that the proposed design procedure may enlarge the class of nonlinear systems for which a nonlinear observer can be obtained     

On the largest feedback linearizable subsystem

A feedback invariant set of integers is associated with any nonlinear multivariable system which is linear with respect to the inputs: it is shown to be the set of controllability indices of the largest feedback linearizable subsystem, i.e. the largest subsystem which can be made locally linear and controllable by means of nonsingular feedback transformations.