Analysis of the gate current as a suitable indicator for FET degradation under nonlinear dynamic regime

Electron device degradation, although not directly accounted for, represents a key issue in microwave circuit design. This is especially true when the particular applications involved (e.g., satellite, military, consumer) do not allow or strongly discourage any kind of maintenance. As a matter of fact, in order to account for device degradation in circuit design, a suitable electron device model is needed which is able to predict the performance degradation as a function of the actual electrical regime involved in the device operation. Such a kind of model is not available in literature. In this paper, quantitative results are provided for device degradation indicators which correlate DC and RF stress experiments. These results can be considered an important step toward the definition of a nonlinear model accounting for device degradation.     

Optimal haulage routing of off-road dump trucks in construction and mining sites using Google Earth and a modified least-cost path algorithm

This study presents new software, called Google Earth-based Optimal HAulage RouTing System (GEOHARTS), to improve the functionality of Google Earth for optimal haulage routing of off-road dump trucks in construction and mining sites. A modified least-cost path algorithm, which is applicable to working areas with both paved and unpaved temporary roads and can consider the effects of terrain relief and curves along a route on the route planning, was proposed and utilized for the software development. GEOHARTS can determine optimal haulage routes between loaders and dumps that ensure the least travel time or fuel consumption of off-road dump trucks and can visualize the results using an embedded 3D render window of Google Earth. The application to the Pasir open-pit coal mine in Indonesia demonstrates that GEOHARTS could provide a rational solution to support the truck haulage operations.     

Evaluating expectations about negative emotional states of aggressive boys using Bayesian model selection.

Researchers often have expectations about the research outcomes in regard to inequality constraints between, e.g., group means. Consider the example of researchers who investigated the effects of inducing a negative emotional state in aggressive boys. It was expected that highly aggressive boys would, on average, score higher on aggressive responses toward other peers than moderately aggressive boys, who would in turn score higher than nonaggressive boys. In most cases, null hypothesis testing is used to evaluate such hypotheses. We show, however, that hypotheses formulated using inequality constraints between the group means are generally not evaluated properly. The wrong hypotheses are tested, i.e.. the null hypothesis that group means are equal. In this article, we propose an innovative solution to these above-mentioned issues using Bayesian model selection, which we illustrate using a case study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Making a mesh router/gateway from a smartphone: Is that a practical solution?

This paper aims at answering the question whether it is practical to build a mesh-phone or not. A mesh-phone is a smartphone acting as a mesh router, i.e. either actively participating in the process of packet forwarding towards a mesh gateway, or acting itself as a gateway toward the Internet. Technical aspects of the mesh-phone implementation, such as design constraints and implementation details, are addressed. The technical feasibility is validated by describing the implementation of a prototype of the mesh-enabled phone over the Openmoko^TM open platform. Besides technical feasibility also convenience of the addressed solution is analyzed in terms of the consumed power, and some “energy-saving” related enhancements are suggested to be applied to future user’s devices.     

Evaluation of anode materials for the electro-oxidation of ammonia and ammonium ions

The electrochemical treatment of effluents has been used as an alternative to conventional treatments because of advantages such as environmental compatibility, process versatility and high efficiency. In addition, electrochemical treatment methods have been demonstrated to be very useful in the treatment of poorly biodegradable effluents. Studies have demonstrated that the electrochemical treatment efficiency is directly related to the electrode material. These materials should have electro-activity for reactions with the targeted pollutants, have high activation energy for undesired reactions and be corrosion resistant. Platinum and DSA^® are known to be effective for the electro-oxidation of pollutants such as phenol, ammonia and ammonium ions. This work presents the results of a comparative evaluation of some materials that can be used as anodes for the electro-oxidation of ammonia and ammonium ions in petroleum refinery effluents. The selected materials were Pt, DSA^®, Ni, anodized Al and graphite. Cyclic voltammograms confirmed the electro-activity of the Pt and DSA^® electrodes and demonstrated the electro-activity of Ni. Anodic polarization revealed the electro-activity of graphite. Anodized Al electrodes showed no activity for the electro-oxidation of the analyzed compounds. The results for the Ni and graphite electrodes are promising.     

Hybrid nanocomposites for mid-range ballistic protection

This paper focuses on ballistic tests of a new class of composite materials, i.e. hybrid nanocomposites. The two hybrid nanocomposites studied are fiber glass/epoxy/nanoclay and fiber glass/epoxy/nanographite. The fiber glass used is a plain weave 200 g/m², while the nanoclay is an organically modified montmorillonite ceramic (Nanomer I30E). The expandable graphite used to generate the graphene nanosheets was from Graftech (grade 160-80N). Ballistic tests were performed considering two types of ammunition, i.e. 38 caliber and 9 mm full metal jacketed. The results showed that for a 38 revolver projectile a 5 mm thick nanocomposite with additional 5 mm nanoclay layer was able to absorb the energy efficiently. A 9 mm projectile, with speed of 380 m/s, was stopped by a two plates (5 mm each) arrangement with elastic deformation of the second plate less than 18 mm. The energies during the ballistic tests ranged from 316 to 576 J.     

Multi-objective design optimization of a new space radiator

In this work different multi-objective techniques are used to the conceptual design of a new kind of space radiator. Called VESPAR (Variable Emittance Space Radiator), the radiator has an effective variable emittance which makes it able to reduce or avoid the demand for heater power to warm up equipment during cold case operations in orbit. The multi-objective approach was aimed on obtaining a radiator that minimize its mass while at the same time minimize the need for heater power during cold case. Four multi-objective algorithms were used: Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II), Multi-Objective Genetic Algorithm (MOGA), Multi-Objective Simulating Annealing (MOSA) and Multi-Objective Generalized Extremal Optimization (M-GEO). The first three algorithms were used under the modeFrontier^® optimization software package, while M-GEO is a recently proposed multi-objective implementation of the Generalized Extremal Optimization (GEO) algorithm. The Pareto frontier showing the trade-off solutions between radiator mass and heater power consumption is obtained by the four algorithms and the results compared. An assessment of the performance of M-GEO on this problem, compared to the other well-known multi-objective algorithms is also made.     

Two-Bands Superconductivity with Intra- and Interband Pairing for Synthetic Superlattices

We consider a model for superconductivity in a two-band superconductor, having an anisotropic electronic structure made of two partially overlapping bands with a first hole-like and a second electron-like Fermi surface. In this pairing scenario, driven by the interplay between interband V _i,j and intraband V _i,i pairing terms, we have solved the two gap equations at the critical temperature T=T _c and calculate T _c and the chemical potential μ as a function of the number of carriers n for various values of pairing interactions, V _1,1, V _2,2, and V _1,2. The results show the complexity of the physics of condensates with multiple order parameters with the chemical potential near band edges.