Reversible Fragmentation and Self‐Assembling of Nematic Liquid Crystal Droplets on Functionalized Pyroelectric Substrates

Investigation on the behavior of nematic liquid crystals on functionalized polar dielectric crystal substrates is accomplished. Very interesting effects can be observed in maneuvering liquid crystal droplets on the substrate surface, driven by electric fields generated by pyroelectric effect. Reversible drops fragmentation and self‐assembling in different configurations can be achieved. The dynamics of the observed phenomena is studied and the repeatability of the process is full assessed.     

FC2Q: exploiting fuzzy control in server consolidation for cloud applications with SLA constraints

Modern cloud data centers rely on server consolidation (the allocation of several virtual machines on the same physical host) to minimize their costs. Choosing the right consolidation level (how many and which virtual machines are assigned to a physical server) is a challenging problem, because contemporary multitier cloud applications must meet service level agreements in face of highly dynamic, nonstationary, and bursty workloads. In this paper, we deal with the problem of achieving the best consolidation level that can be attained without violating application service level agreements. We tackle this problem by devising fuzzy controller for consolidation and QoS (FC2Q), a resource management framework exploiting feedback fuzzy logic control, that is able to dynamically adapt the physical CPU capacity allocated to the tiers of an application in order to precisely match the needs induced by the intensity of its current workload. We implement FC2Q on a real testbed and use this implementation to demonstrate its ability of meeting the aforementioned goals by means of a thorough experimental evaluation, carried out with real‐world cloud applications and workloads. Furthermore, we compare the performance achieved by FC2Q against those attained by existing state‐of‐the‐art alternative solutions, and we show that FC2Q works better than them in all the considered experimental scenarios. Copyright © 2014 John Wiley & Sons, Ltd.     

Structural defects in (100) 3C-SiC heteroepitaxy: Influence of the buffer layer morphology on generation and propagation of stacking faults and microtwins

Growth of 3C-SiC on (100) Si has been performed via chemical vapor deposition under two pressure regimes (low and atmospheric pressure) in the early stage of growth. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) have been conducted to study the initial stage of growth while X-ray diffractometry (XRD) and TEM have been used to analyze thicker films and to detect and quantify defects, resulting in a comprehensive and detailed investigation of 3C-SiC structural defects. We have found out that the secondary nucleation of 3C-SiC island growth leads to a higher defect generation rate and, at the same time, to a more effective defect elimination rate. Hillocks found on the surface of thin samples grown under reduced pressure conditions are more pronounced as they seem to be a consequence of twins created in the early stage of growth. Finally, a different initial nucleation density (in the two pressure regimes considered) does not strongly influence stacking fault and microtwin density when growth of thick 3C-SiC films is performed. A very strong influence is indeed observed when 3C-SiC thickness is limited to hundreds of nanometers.     

The influence of hydrogen and nitrogen on the formation of Si nanoclusters embedded in sub-stoichiometric silicon oxide layers

This work reports the study concerning the influence of the preparation conditions on the structure of silicon rich oxide (SRO) deposited by PECVD method by which the structural properties of the film are strictly related. In particular we investigated the role of reactant gases N₂O and SiH₄ on the total Si concentration, Si excess concentration, Si clustered concentration and size of nanoclusters formed by high annealing temperature. We payed particular attention on the role of the hydrogen and nitrogen during the Si agglomeration.The presence of hydrogen atoms on the as-deposited specimen, confirmed by the Si–H bonds peak on the FTIR analysis, has been directly correlated to the silicon excess concentration in the layer. The silicon, oxygen and nitrogen atomic density has been calculated from RBS analysis. These information were coupled to the ones obtained using methodology based on electron energy loss spectroscopy combined with energy filtered images, which allowed us to quantify the clustered silicon concentration in annealed sub-stoichiometric silicon oxide layers (SiO_x). We have verified that the nitrogen dissolved in the layer inhibits the Si excess clustering so that the efficiency of silicon agglomeration process decreases as the nitrogen content increases.     

Response to comment on ‘Persistent inputs and the standard H2 multivariable control problem’ by K. Park and J.J. Bongiorno Jr

Layered networks are used in a nonlinear adaptive control problem. The plant is an unknown feedback-linearizable discrete-time system, represented by an input-output model. A state space model of the plant is obtained to define the zero dynamics, which are assumed to be stable. A linearizing feedback control is derived in terms of some unknown nonlinear functions. To identify these functions, it is assumed that they can be modelled by layered neural networks. The weights of the networks are updated and used to generate the control. A local convergence result is given. Computer simulations verify the theoretical result.     

Software development tool for target systems and EPROM programmers within a Unix environment

A computer running under a Unix operating system is an excellent host on which to develop software for target systems which have the same type of microprocessor as the host computer. Unfortunately, facilities for preparing executable modules able to be sent to an EPROM programmer or to be loaded onto a RAM portion of target memory space are lacking in standard Unix. These facilities can be improved in any version of Unix without the need for expensive software using the set of commands presented in this paper.     

Energy intensity of maritime trades: Evidences from the EX-TREMIS database

This paper describes the energy consumption performance of sea-going ships engaged in the EU27 seaborne trades based on data and parameters resulting from the EX-TREMIS (EXploring non road TRansport EMISsions in Europe) database. EX-TREMIS is a comprehensive database of fleet and transport activity data, specific energy consumption, emission factors and total emissions from rail, maritime and air transport in the European Union. The EX-TREMIS maritime model derives from a mixture of top–down and bottom–up approaches for estimating pollutant emissions from shipping activities. The model did not use direct observations of actual trips, but empirically derived the number of equivalent-ships. Cargo type shipments were linked to seven ship type categories for which a further segmentation by ship size (three length classes), type and age of the main engine and type of fuel was applied.