Electronically reconfigurable superimposed waveguide long-period gratings

The perturbation to the refractive index induced by a periodic electric field from two systems of interdigitated electrodes with the electrode-finger period l is analyzed for a waveguide with an electro-optically (EO) active core-cladding. It is shown that the electric field induces two superimposed transmissive refractive-index gratings with different symmetries of their cross-section distributions. One of these gratings has a constant component of an EO-induced refractive index along with its variable component with periodicity l, whereas the second grating possesses only a variable component with periodicity 2l. With the proper waveguide design, the gratings provide interaction between a guided fundamental core mode and two guided cladding modes. Through the externally applied electric potential, these gratings can be independently switched ON and OFF, or they can be activated simultaneously with electronically controlled weighting factors. Coupling coefficients of both gratings are analyzed in terms of their dependence on the electrode duty ratio and dielectric permittivities of the core and cladding. The coupled-wave equations for the superimposed gratings are written and solved. The spectral characteristics are investigated by numerical simulation. It is found that the spectral characteristics are described by a dual-dip transmission spectrum with individual electronic control of the dip depths and positions. Within the concept, a new external potential application scheme is described in which the symmetry of the cross-sectional distribution of the refractive index provides coupling only between the core mode and the cladding modes, preventing interaction of the cladding modes with each another. This simple concept opens opportunities for developing a number of tunable devices for integrated optics by use of the proposed design as a building block.     

A fuzzy neighborhood-based training algorithm for feedforward neural networks

In this work we present a new hybrid algorithm for feedforward neural networks, which combines unsupervised and supervised learning. In this approach, we use a Kohonen algorithm with a fuzzy neighborhood for training the weights of the hidden layers and gradient descent method for training the weights of the output layer. The goal of this method is to assist the existing variable learning rate algorithms. Simulation results show the effectiveness of the proposed algorithm compared with other well-known learning methods.     

Beneficial Effects of Silicon (Si) on Sea Barley (Hordeum marinum Huds.) under Salt Stress

Silicon - Silicon (Si) plays an important role in providing beneficial effects on plant growth and yield, especially under stressful environments such as salinity. The objective of this work is to...     

Micro mobility in the IP networks

Wireless access to Internet services will become typical, rather than the exception as it is today. Such a vision presents great demands on mobile networks. Mobile IP represents a simple and scalable global mobility solution but lacks the support for fast handoff control and paging found in cellular telephony networks. In contrast, second- and third-generation cellular systems offer seamless mobility support but are built on complex and costly connection-oriented networking infrastructure that lacks the inherent flexibility, robustness, and scalability found in IP networks. This paper presents an overview and performance comparison of two of the main micro-mobility protocols, namely Cellular IP and Hierarchical Mobile IP with regards to the handoff process for UDP applications. The differences in the handoff quality of the two protocols are small and can be traced to design choices within the typical model. There are however significant differences regarding the processing requirement, routing efficiency and parameters relating to implementation and deployment.     

Removal of Basic Red 46 dye from aqueous solution by adsorption onto Moroccan clay

In this study, Moroccan crude clay of Safi, which was characterized by X-ray diffraction, is used as adsorbent for the investigation of the adsorption kinetics, isotherms and thermodynamic parameters of the Basic Red 46 (BR46) in aqueous solutions at various dye concentrations, adsorbent masses and pH values. The results showed that the adsorption capacity of the dye increased by initial dye concentration and pH values. Two kinetic models (the pseudo-first-order and the pseudo-second-order) were used to calculate the adsorption rate constants. The adsorption kinetics of the basic dye followed pseudo-second-order model. The experimental data isotherms were analyzed using the Langmuir, Freundlich and Dubinin–Radushkevish equations. The monolayer adsorption capacity for BR46 dye is 54 mg/g of crude clay. Nearly 20 min of contact time was found to be sufficient for the dye adsorption to reach equilibrium. Thermodynamical parameters were also evaluated for the dye–adsorbent system and revealed that the adsorption process is exothermic in nature.     

Frequency estimation in the presence of Doppler spread: performanceanalysis

We are concerned with the estimation of the frequency of a complex sinusoid that has been corrupted by complex-valued multiplicative and additive noise. This problem is important in many applications including array processing in the case of spatially distributed sources and synchronization in the context of time-selective channels. The multiplicative noise smears the spectral line due to the sinusoid. This smearing, which is often called Doppler spreading, may significantly degrade the estimation accuracy. The goal of this paper is to analytically assess this degradation. The finite-sample Cramer-Rao bounds (CRBs) are derived, and closed-form expressions are given for the large-sample CRB. The latter gives insights into the effective coherent and noncoherent SNRs for frequency estimation. We then analyze the accuracy of frequency estimators that are based on the angles of the sample covariances. Simulations results are presented to illustrate the theoretical results     

Example-based model-transformation testing

A major concern in model-driven engineering is how to ensure the quality of the model-transformation mechanisms. One validation method that is commonly used is model transformation testing. When using this method, two important issues need to be addressed: the efficient generation/selection of test cases and the definition of oracle functions that assess the validity of the transformed models. This work is concerned with the latter. We propose a novel oracle function for model transformation testing that relies on the premise that the more a transformation deviates from well-known good transformation examples, the more likely it is erroneous. More precisely, the proposed oracle function compares target test cases with a base of examples that contains good quality transformation traces, and then assigns a risk level to them accordingly. Our approach takes inspiration from the biological metaphor of immune systems, where pathogens are identified by their difference with normal body cells. A significant feature of the approach is that one no longer needs to define an expected model for each test case. Furthermore, the detected faulty candidates are ordered by degree of risk, which helps the tester inspect the results. The validation results on a transformation mechanism used by an industrial partner confirm the effectiveness of our approach.     

Adaptation of a routing algorithm in wireless video sensor network for disaster scenarios using JPEG 2000

In this work we will develop an extension of one of existing routing algorithm in wireless sensor network. This new adaptation will permit the sensor node to save more energy and transmit images in wireless mode. This situation will be strategic and helpful especially in disaster scenario, where groups of rescuers must be on site to accomplish emergency tasks; therefore it’s very important and necessary to establish a wireless communication in real time between individuals or groups. The nature of wireless video sensor network makes it suitable to be used in the context of emergencies because introducing a video give more information in precise time and this is very advantageous when the existing infrastructure is down or severely overloaded. In emergencies the network topology may change rapidly and randomly. The increasing mobility of terminals makes them progressively dependent on their autonomy from the power source. This is illustrated by introducing many mobility models and using many scenarios of mobility in emergency situation, where image transmission via sensor node is used. Low complexity algorithm in image processing in order to reduce time transfer of selected data by this way allows saving energy. Efficiency in emergency scenario is the main objective of this work, achieved by the combination of three strategies: low-power mode algorithm, a power-aware routing strategy and compression technique in image processing used in sensor node. A selected set of simulations studies and real test bed on sensor node platform (Telos-B) indicate a reduction in energy consumption and a significant increase in node lifetime whereas network performance is not affected significantly. This is the big interest of our work in emergency situation, by increasing life time of node, individual can communicate longer and give more chance to rescuers to find them.