Spatial P systems

We present Spatial P systems, a variant of P systems which embodies the concept of space and position inside a membrane. Objects in membranes are associated with positions. Rules specify, in the usual way, the objects which are consumed and the ones which are produced; in addition, they can specify the positions of the produced objects. Objects belong to two different sets: the set of ordinary objects and the set of mutually exclusive objects. Every position inside a membrane can accommodate an arbitrary number of ordinary objects, but at most one mutually exclusive object. We prove that Spatial P systems are universal even if only non-cooperating rules are allowed. We also show how Spatial P systems can be used to model the evolution of populations in presence of geographical separations.     

Image Analysis Techniques for Automated Hazelnut Peeling Determination

According to FAO statistics, in 2000, Italy was the second largest hazelnut (Corylus avellana, L. 1753) producer in the world. The price of the stock depends on the nut quality (kernel/nut ratio, nut and seed defect, percentage of peeling, and taste panel scores). The evaluation of peeling efficiency after toasting is generally conducted by trained operators in sight on 100 kernels. This work tests two alternative objective methods of after toasting peeling evaluation based on image analysis. Eleven hazelnut cultivars were analyzed and results were compared with the ones assessed by trained operators. Images were analyzed with two statistical approaches: fixed values of RGB thresholding and trained K Nearest Neighbors (KNN). Root mean squared error (RMSE), estimating the comparison between operators and the two image analysis-based techniques, shows better results for KNN (6.6) with respect to fixed threshold (15.9).     

Hierarchical Porosity Components by Infiltration of a Ceramic Foam

A ceramic body with hierarchical meso–macro-porosity was prepared by depositing a mesoporous silica coating on the walls of a macroporous silicon oxycarbide (SiOC) foam. Scanning electron microscopy, transmission electron microscopy, and small-angle X-ray scattering revealed that a uniform mesoporous coating was deposited on the walls of the macropores, with the mesopores arranged in a highly ordered cubic lattice. Nitrogen adsorption measurements showed a bimodal pore size distribution and revealed that the specific surface area is one order of magnitude higher than in macroporous SiOC foams. Therefore, interesting applications in adsorption and catalysis can be devised.     

Control of beam vibrations by means of piezoelectric devices: theory and experiments

The problem of the attenuation of the vibration effects in active cantilever beams has been approached by two strategies, position and velocity control, which have been simulated numerically and analysed experimentally. The numerical simulation has been developed by means of a finite element approach based on an Euler–Bernoulli model and subsequent modal factorisation. Each device as well as each electronic circuit, present in the single-input single-output control system has been modelled and the results of the numerical simulations have been compared with the ones obtained in the experimental tests. A good correspondence has been obtained in all the examined cases.     

Influence of invariant material parameters on the flexural optimal design of thin anisotropic laminates

A general discussion of the optimal solutions to the problems of maximum stiffness, buckling load and modal frequencies for rectangular laminates is proposed. The study is based upon some invariant dimensionless material parameters. The conditions giving rise to the same objective function for the three cases are discussed and a new physical meaning of the objective as a stiffness modulus is proposed. The geometrical and material conditions giving rise to non-trivial optimal solutions are also discussed.     

Spectral Green's Functions for Layered Gyrotropic Structures Through a Transmission-Line Approach

In this work, a straightforward method is shown to derive spectral Green's functions in classes of planar structures including gyrotropic media, based on a recently proposed transmission-line formalism. In particular, the analysis is expressly carried out for a current line source in layered configurations with transversely-magnetized ferrites, useful for microwave and millimeter-wave waveguiding and radiating devices.     

CASTTGRINDING~:灵活的环保型板坯表面精整工艺

CASTTGRINDINGR○ (铸造温度修磨 )工艺 ,通过对连铸板坯进行在线热精整 ,使其能够将板坯连铸生产与热轧工艺有机地形成一个整体。介绍了 CASTTGRINDINGR○热修磨工艺的主要特点和带来的好处 ,并举例说明与目前在碳钢精整时通常采用的传统式火焰清理设备相比 ,新工艺拥有的主要优点