Varactor-tuned quarter-wavelength dual-bandpass filter

A tunable dual-band bandpass microstrip filter is proposed and presented. It is composed of two pairs of quarter-wavelength transmission line resonators and two bandstop structures made of open stubs. Each operation bandpass frequency, denoted by f/sub 1/and f/sub 2/, is generated by a pair of coupled resonators. The first coupled resonator is fed via a tap-coupled structure, while the second is fed through a coupling structure. The tunability of each bandpass and harmonic suppression is achieved by modifying the electrical length of the resonators and the electrical length of the open stubs by using varactor-diode capacitors. Finally, a 2.5 and 4.25 GHz dual band bandpass filter is designed, fabricated and measured as one example and a tunability of 22.2% and 19.6%, respectively, is obtained for the first and second bands. These excellent experimental results validate the proposed structure and design technique for dual-band bandpass filters.     

New multi-objective approach for dynamic risk-driven intrusion responses

1 Introduction Several active intrusion response mechanisms have been designed and prototyped,They adapt well to specificities of the monitored system,though they lack explicit and clear pro-cesses to select new security controls or evaluate existing ones.However,they have never considered risk models as recommended by ISO 27002 and ISO 27005 to assess and mitigate risks of mounted attacks[1,2].Additionally,they have several drawbacks in cost factor assessment as well as in countermeasure selection.     

Efficient transform-based texture image retrieval techniques under quantization effects

With the great demand for storing and transmitting images as well as their managing, the retrieval of compressed images is a field of intensive research. While most of the works have been devoted to the case of losslessly encoded images (by extracting features from the unquantized transform coefficients), new studies have shown that lossy compression has a negative impact on the performance of conventional retrieval systems. In this work, we investigate three different quantization schemes and propose for each one an efficient retrieval approach. More precisely, the uniform quantizer, the moment preserving quantizer and the distribution preserving quantizer are considered. The inherent properties of each quantizer are then exploited to design an efficient retrieval strategy, and hence, to reduce the drop of retrieval performances resulting from the quantization effect. Experimental results, carried out on three standard texture databases and a color dataset, show the benefits which can be drawn from the proposed retrieval approaches.     

Reinforcing potential of nanofibrillated cellulose from nonwoody plants

In the present work the reinforcing potential of nanofibrillated cellulose (NFC) from five different non‐woody plants, namely; abaca, sisal, hemp, jute and flax was investigated. Nanocomposite materials were prepared by casting a mixture of NFC suspension and a polymer waterborne latex dispersion, and their mechanical properties in both linear and nonlinear ranges as well as the optical properties of the ensuing films were analyzed. Irrespective of their origin, the incorporation of the NFC within the polymer matrix brings about a huge reinforcing effect above the glass transition. The percolation approach has been shown to give a reasonably accurate prediction of the stiffness over the whole range of volume fraction investigated. The evolution of the magnitude of tan δ vs. the NFC content was also analyzed and discussed in term of the effective interfacial thickness. The optical transparency of the nanocomposite film at different NFC content was also studied and compared according to the NFC origin. POLYM. COMPOS., 34:1999–2007, 2013. © 2013 Society of Plastics Engineers     

MADCR:Mobility Aware Dynamic Clustering-Based Routing Protocol in Internet of Vehicles

Internet of Vehicles (IoV) is an evolution of the Internet of Things (IoT) to improve the capabil-ities of vehicular ad-hoc networks (VANETs) in in-telligence t...     

Slow-Wave Line Coupler With Interdigital Capacitor Loading

In this study, a full-wave-based circuit model of an interdigital capacitor in the form of a coplanar waveguide (CPW) configuration is studied by using numerical thru-reflect-line calibration techniques, which can easily be combined with commercial electromagnetic simulation software. Subsequently, a slow-wave line coupler is proposed and realized for size miniaturization by loading different interdigital capacitors onto a coupled CPW line, which has equal phase velocities for both odd and even modes. An experimental prototype is fabricated, and measured results show a good agreement with simulated ones, thereby demonstrating an excellent performance.     

Applicability of some statistical tools to predict optimum adsorption isotherm after linear and non-linear regression analysis

In any single component isotherm study, determining the best-fitting model is a key analysis to mathematically describe the involved sorption system and, therefore, to explore the related theoretical assumptions. Hence, several error calculation functions have been widely used to estimate the error deviations between experimental and theoretically predicted equilibrium adsorption values (Q(e,exp)vs.Q(e,theo) as X- and Y-axis, respectively), including the average relative error deviation, the Marquardt's percent standard error deviation, the hybrid fractional error function, the sum of the squares of the errors, the correlation coefficient and the residuals. In this study, five other statistical functions are analysed to investigate their applicability as suitable tools to evaluate isotherm model fitness, namely the Pearson correlation coefficient, the coefficient of determination, the Chi-square test, the F-test and the Student's T-test, using the commonly-used functions as references. The adsorption of textile dye onto Posidonia oceanica seagrass fibres was carried out, as study case, in batch mode at 20 degrees C. Besides, and in order to get an overall approach of the possible utilization of these statistical functions within the studied item, the examination was realized for both linear and non-linear regression analysis. The related results showed that, among the five studied statistical tools, the chi(2) and Student's T-tests were suitable to determine the best-fitting isotherm model for the case of linear modelling approach. On the other hand, dealing with the non-linear analysis, despite the Student's T-test, all the other functions gave satisfactorily results, by agreeing the commonly-used error functions calculation.     

Fabrication of porous Pt-Pd electrodes using solid state interdiffusion

Partial burnt off process of sacrificial material while fabricating porous electrode for gas sensors and fuel cells brings uncertainties about reaction of gas species with remained sacrificial material. Here, efforts were devoted to fabricate a porous electrode with high electrical conductivity without using sacrificial carbon material. To do so, bilayers of Pt/Pd were deposited over Yttria Stabilized Zirconia substrate and thermally treated at 500 °C for different annealing times. As a result of annealing, solid state interdiffusion between Pt and Pd was activated resulting to generation of Pd accompanied with pores on the surface of Pt layer. Moreover, 10 min annealing leads to higher electrical conductivity of intermixed layer which is most probably due to a reduction in grain boundary resistivity of the host material. It has been shown that 10 min annealed bilayers of Pt/Pd exhibit promising characteristics in terms of porosity and electrical conductivity. It was concluded that solid state interdiffusion was introduced as an effective method to fabricate porous conductive layers which has potential applications in gas sensors and fuel cells.     

Uncertain Saturated Discrete‐Time Sliding Mode Control for A Wind Turbine Using A Two‐Mass Model

The aim of this paper is to propose a new design variable speed wind turbine control by discrete‐time sliding mode approach. The control objective is to obtain a maximum extraction of wind energy, while reducing mechanical loads and rotor speed tracking combined with an electromagnetic torque. For this application, we designed a discrete time sliding mode control using the equivalent discrete time reaching law. Furthermore, a systematic and improved design procedure for uncertainties discrete‐time sliding mode control (SMC) with saturation problem is provided in this paper. The saturation constraint is reported on inputs vector. LMI technique and polytopic models are used in the design of the switching surface. To achieve some performance requirements and good robustness, in the sliding mode, the pole clustering method is investigated. Based on the unit vector control approach, a robust control is developed, then, to direct and maintain the system states onto the sliding manifold in finite time. Finally, a systematic design procedure for DSMC required to achieve a given performance level is provided and its effectiveness is varied by applying it to variable speed wind turbine systems.