Digital signature to help network management using flow analysis

Because of constant growth in proportion and complexity of networks, flow analysis has become an indispensable tool for network management mechanisms. Through this resource, a traffic characterization, called digital signature of network segment using flow analysis (DSNSF), is accomplished. The models used for this purpose are the ant colony optimization metaheuristic, the Holt–Winters forecasting method and the statistical procedure, principal component analysis. The obtained DSNSF by each model is compared with the actual traffic of packets and bits and then subjected to specific evaluations in order to measure its accuracy. The experimental results show that the three methods could achieve good correlation indices and low normalized mean square error values between the DSNSF curve and the real traffic movement, indicating a good adaptability and efficiency in characterizing a network traffic segment. Copyright © 2015 John Wiley & Sons, Ltd.     

Effects of time of grape pomace fermentation and distillation cuts on the chemical composition of grape marcs

 The effects of fermentation time and distillation cuts on the composition of distillates in terms of ethanal, 1,1-diethoxyethane, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl acetate, ethyl 2-hydroxypropanoate, 3-methylbutyl acetate, hexyl acetate, 2-phenylethyl acetate, hexanol, trans-2-hexenol, trans-3-hexenol, cis-3-hexenol, 2-phenylethanol, ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl dodecanoate, 2-methylpropanoic acid, 3-methylbutanoic acid, hexanoic acid, octanoic acid, decanoic acid, and dodecanoic acid were assessed through data generated according to a factorial design using analysis of variance and principal component analysis. Four times of storage of pomace obtained following winemaking of two grape varieties of white Verde wine (Alvarinho and Loureiro) and three distillation cuts were considered; volatile compounds in the 24 samples generated were analyzed directly, and indirectly after extraction and concentration, by capillary gas chromatography. The results generated have suggested clear differences (P<0.05) between distillate cuts obtained throughout fermentation times for each grape variety. The major differences between the different distillate fractions analyzed were accounted for by the contents of diethyl butanoate, ethyl 2-hydroxypropanoate, and the sum of 3-methylbutanoic and 2-methylpropanoic acids for Loureiro, whereas the main differences were accounted for by the contents of diethyl butanoate and the sum of the carboxylic acids for Alvarinho.     

In vivo measurement of the brain and skull resistivities using an EIT-based method and realistic models for the head

In vivo measurements of equivalent resistivities of skull (rho(skull)) and brain (rho(brain)) are performed for six subjects using an electric impedance tomography (EIT)-based method and realistic models for the head. The classical boundary element method (BEM) formulation for EIT is very time consuming. However, the application of the Sherman-Morrison formula reduces the computation time by a factor of 5. Using an optimal point distribution in the BEM model to optimize its accuracy, decreasing systematic errors of numerical origin, is important because cost functions are shallow. Results demonstrate that rho(skull)/rho(brain) is more likely to be within 20 and 50 rather than equal to the commonly accepted value of 80. The variation in rho(brain)(average = 301 omega x cm, SD = 13%) and rho(skull)(average = 12230 omega x cm, SD = 18%) is decreased by half, when compared with the results using the sphere model, showing that the correction for geometry errors is essential to obtain realistic estimations. However, a factor of 2.4 may still exist between values of rho(skull)/rho(brain) corresponding to different subjects. Earlier results show the necessity of calibrating rho(brain) and rho(skull) by measuring them in vivo for each subject, in order to decrease errors associated with the electroencephalogram inverse problem. We show that the proposed method is suited to this goal.     

Dispersion in finlines on semiconductor and the S-parameters of a step discontinuity

The Transverse Transmission Line method is used for the characterization of bilateral and unilateral finlines on a semiconductor substrate and in conjunction with the modal method, for the calculation of the scattering parameters due to a step discontinuity on a unilateral finline with a lossless dielectric substrate. Numerical results of the effective dielectric constant, attenuation constant and characteristic impedance for the bilateral and unilateral finlines on semiconductor substrates, and results of scattering parameters of a step discontinuity for unilateral finline, are presented.     

Analysis of microstrip antennas on circular-cylindrical substrateswith a dielectric overlay

The use of dyadic Green's functions and the moment method is explored for the solution of microstrip antenna problems on circular cylindrical substrates. The dyadic Green's functions of the electric type are obtained for a medium consisting of three cylindrical dielectric layers concentric with a perfectly conducting cylinder, and integral equations are developed for the evaluation of the electromagnetic fields. The effect of a dielectric overlay on the resonant frequency of a cylindrical-rectangular microstrip antenna is analyzed. The patch is directly fed by means of a microstripline printed along the cylinder axial direction. The results show that the effect of the dielectric overlay is substantial when its relative permittivity and thickness are increased, such that this effect has to be very carefully considered in the design of microstrip antennas     

Integrated structure and control design for mechatronic systems with configuration-dependent dynamics

This paper considers the optimal design of mechatronic systems with configuration-dependent dynamics. An optimal mechatronic design requires that, among the structural and control parameters, an optimal choice has to be made with respect to design specifications in the different domains. Two main challenges are treated in this paper: the non-convex nature of the optimization problem and the difficulty in modeling serial machines with flexible components and their embedded controllers. The optimization problem is treated using the direct design strategy which considers simultaneously structural and control parameters as variables and adopts non-convex optimization algorithms. Linear time-invariant and gain-scheduling PID controllers are addressed. This methodology is exploited for the multi-objective optimization of a pick-and-place assembly robot with a gripper carried by a variable-length flexible beam. The resulting design tradeoffs between system accuracy and control efforts demonstrate the advantage of an integrated design approach for mechatronic systems with configuration-dependent dynamics.     

A Multi-user Receiver for Inter-Cell Interference Reduction in LTE PUCCH Signaling

In 3rd generation partnership project (3GPP) long term evolution (LTE) systems, when no resources has been assigned in the uplink to a given user equipment (UE), the control information associated with layers 1 and 2 in the protocol stack is conveyed back to the base station through the so-called physical uplink control channel (PUCCH). In PUCCH, the data streams transmitted by multiple UEs are multiplexed in the time-domain and in the frequency-domain with the aid of spreading codes. Although the spreading codes associated with UEs within the same cell can be assumed to be orthogonal, the presence of inter-cell interference (ICI) in multi-cell scenarios severely limits receiver performance. In particular, the Format 1 of PUCCH, which is associated with the transmission of hybrid automatic repeat request acknowledgements (ACK/NACK) and scheduling requests, has a major impact on system performance, since an incorrectly decoded ACK/NACK message may introduce significant delay in data transmission. In this contribution, we propose a new multi-user receiver for ICI reduction in PUCCH LTE that operates both in cooperative and non-cooperative multi-cell architectures. The proposed receiver relies on a constrained tensor modeling of the received signal in PUCCH signaling, and affords an iterative joint channel estimation and symbol detection by simultaneously exploiting the energy of the data symbols and the pilot tones present in PUCCH. The formulation of the proposed algebraic receiver model incorporates symbol-basis hopping and slot-basis hopping signaling schemes, which are interference randomization techniques existing in the 3GPP specifications of LTE system. Computer simulation results show the remarkable performance gains of the proposed receiver compared to the conventional time-frequency decorrelator based receiver.     

Advances in Ground Transmitters for the NASA Deep Space Network

The Deep Space Network (DSN), managed by the Jet Propulsion Laboratory for NASA, is equipped with multiple microwave transmitters ranging in average radiated power from 200 W to 400 kW. The transmitters are used for routine or emergency communication with spacecraft, for navigation, and for radio science tasks. The latest advances in transmitter engineering were implemented in a new generation of 20-kW dual-band transmitters developed for the DSN 34-m beam waveguide antennas. Innovations include additional X-band communication capability for near Earth missions, new c, automated calibration, improved and expanded computerized monitoring and diagnostics, reduced cabling, and improved maintainability. The innovations were very beneficial for the DSN ldquooverloadrdquo during the Mars 2003/2004 missions and will benefit other missions throughout the next decade. This paper describes the current design of the new transmitters and possible future developments.     

High-Performance ITO-Free Perovskite Solar Cells Enabled by Single-Walled Carbon Nanotube Films

The unprecedented advancement in power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) has rendered them a promising game-changer in photovoltaics. However, unsatisfactory environmental stability and high manufacturing cost of window electrodes are bottlenecks impeding their commercialization. Here, a strategy is introduced to address these bottlenecks by replacing the costly indium tin oxide (ITO) window electrodes via a simple transfer technique with single-walled carbon nanotubes (SWCNTs) films, which are made of earth-abundant elements with superior chemical and environmental stability. The resultant devices exhibit PCEs of ≈19% on rigid substrates, which is the highest value reported to date for ITO-free PSCs. The facile approach for SWCNTs also enables application in flexible PSCs (f-PSCs), delivering a PCE of ≈18% with superior mechanical robustness over their ITO-based counterparts due to the excellent mechanical properties of SWCNTs. The SWCNT-based PSCs also deliver satisfactory performances on large-area (1 cm² active area in this work). Furthermore, these SWCNT-based PSCs can retain over 80% of original PCEs after exposure to air over 700 h while ITO-based devices only sustain ≈60% of initial PCEs. This work paves a promising way to accelerate the commercialization of ITO-free PSCs with reduced material cost and prolonged lifetimes.     

Use of support vector regression and numerically predicted cloudiness to forecast power output of a photovoltaic power plant in Kitakyushu,Japan

The development of a methodology to forecast accurately the power produced by photovoltaic systems can be an important tool for the dissemination and integration of such systems on the public electricity grids. Thus, the objective of this study was to forecast the power production of a 1‐MW photovoltaic power plant in Kitakyushu, Japan, using a new methodology based on support vector machines and on the use of several numerically predicted weather variables, including cloudiness. Hourly forecasts of the power produced for 1 year were carried out. Moreover, the effect of the use of numerically predicted cloudiness on the quality of the forecasts was also investigated. The forecasts of power production obtained with the proposed methodology had a root mean square error of 0.0948 MW h and a mean absolute error of 0.058 MW h. It was also found that the forecast and measured values of power production had a good level of correlation varying from 0.8 to 0.88 according to the season of the year. Finally, the use of numerically predicted cloudiness had an important role in the accuracy of the forecasts, and when cloudiness was not used, the root mean square error of the forecasts increased more than 32%, and the mean absolute error increased more than 42%. Copyright © 2011 John Wiley & Sons, Ltd.