Outage analysis of blind cooperative diversity

Mobile users with single antennas can still take advantage of spatial diversity through cooperative space–time‐encoded transmission. In this paper, we considered a scheme in which a relay chooses to cooperate only if its source–relay channel is of an acceptable quality, and we evaluate the usefulness of relaying when the source acts blindly and ignores the decision of the relays whether they may cooperate or not. In our study, we consider the regenerative relays in which the decisions to cooperate are based on a targeted end‐to‐end data rate R. We derived the end‐to‐end outage probability for a transmission rate R and a code rate ρ and look at a power allocation strategy between the source and the relays in order to minimize the end‐to‐end outage probability at the destination for high signal‐to‐noise ratio, by using the golden section search method. Performance results show that the computer simulations‐based results coincide with our analytical results. Copyright © 2011 John Wiley & Sons, Ltd.     

Transient response of a rotor-AMBs system connected by a flexible mechanical coupling

In this paper, the effect of angular misalignment on the transient dynamics of a rotor-Active Magnetic Bearings (AMBs) system was examined with numerical analysis. A spatial model of a misaligned rotor mounted in two identical AMBs is setup to account angular misalignment with a flexible coupling having torsional and lateral flexibility. The driving rotor was powered by an electric motor in transient regime. Three models of AMBs were used with four; six and eight magnets. They were powered by bias and control current. The AMBs dynamics support parameters were modeled by stiffness and damping matrices. These were computed through an electromagnetic theory and derivation of the magnetic forces. The general equations of motion of the driven rotor were derived and solved using the Newmark time integration method. Simulation results were carried out to determine the frequency and transient responses in term of misalignment magnitude. Dynamic responses come to confirm a significant influence of the transient regime on the dynamic behavior of misaligned rotor. Simulated results also reveal that vibrations induced by angular misalignment were more important in the case of AMBs with four magnets. Spectral components of the system response were investigated, in sort to present diagnostic information about the signature of this kind of fault in transient regime.     

First assessment of the ecological status of Karaoun reservoir,Lebanon

Many reservoirs have been constructed throughout the world during the 20th century, with many also suffering from eutrophication. The resulting increased phytoplankton biomass in reservoirs impairs their use. Except for Lake Kinneret, the environmental status of lakes and reservoirs in the Middle East is poorly documented. Karaoun reservoir, also known as Qaroun, Qaraoun or Qarun, is the largest water body in Lebanon, having been constructed for irrigation and hydropower production. This present study reviews Karaoun reservoir, including its characteristics, uses, water quality and phytoplankton succession, to assess the environmental status of the reservoir on the basis of the few existing previous publications about the reservoir. Since 2004, which is 39 years after its construction, the reservoir is considered to be hypereutrophic, with low phytoplankton biodiversity and regular blooms of toxic cyanobacteria. The nutrient and trace metal concentrations would not prevent use of the reservoir for a drinking water supply for Beirut, as is currently being planned, although not all the micropollutants in the lake were documented. Karaoun reservoir is compared to other monitored lakes and reservoirs around the Mediterranean Sea. They share annual toxic cyanobacteria blooms of Aphanizomenon ovalisporum and of Microcystis aeruginosa. The phytoplankton composition and succession of Karaoun reservoir is more similar to El Gergal reservoir (Spain) than nearby natural lakes such as Lake Kinneret (Israel) and Lake Trichonis (Greece). Phytoplankton diversity in Karaoun reservoir was the lowest, due to higher nutrient concentrations and a larger decrease in water level in the dry season. Karaoun reservoir represents an interesting example of the potential response of the phytoplankton community in other lakes and reservoirs during the drought periods expected to occur as a result of global climate change.     

Random polyesteramides based on ε‐caprolactone and glycine

A series of random polyesteramides (PEAs) based on ε‐caprolactone and glycine were synthesized by a direct melt polycondensation method. Their structure was fully characterized by NMR spectroscopy. High molar mass PEAs were obtained for glycine contents lower than 15 mol‐%. The resulting copolymers are semi‐crystalline and present increasing glass transition temperatures but decreasing melting points at increasing glycine contents. Some of these PEAs exhibit better thermal stability and higher Young's modulus and ultimate tensile strength than PCL homopolymer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40573.     

Some Results on Convolutional Coupled Codes: Distance Properties, Performance, and Design

The class of Convolutional Coupled Codes is a promising alternative to classical Turbo-Codes. A Convolutional Coupled Code consists of a cascade of ν identical recursive systematic convolutional (RSC) outer codes and k inner block codes with parameters (2ν, ν, d_i). The codes are linked together such that only the systematic part of the outer codes is encoded with the inner block encoders. Only the redundancy from the inner and outer codes are transmitted. An estimation of the minimum distance is derived. The influence of number, code memory and code polynomials of the outer RSC codes on the distance properties and the convergence behavior of the iterative decoding scheme is studied. With respect to this results, we present a guideline for the optimal design of the RSC outer codes.     

On the feedback error compensation for adaptive modulation and coding scheme

In this paper, we consider the effect of feedback error on the performance of the joint adaptive modulation and diversity combining (AMDC) scheme which was previously studied with an assumption of perfect feedback channels. We quantify the performance of two joint AMDC schemes in the presence of feedback error, in terms of the average spectral efficiency, the average number of combined paths, and the average bit error rate. The benefit of feedback error compensation with adaptive combining is also quantified. Selected numerical examples are presented and discussed to illustrate the effectiveness of the proposed feedback error compensation strategy with adaptive combining. Copyright © 2011 John Wiley & Sons, Ltd.     

Vehicle longitudinal motion modeling for nonlinear control

The problem of modeling vehicle longitudinal motion is addressed for front wheel propelled vehicles. The chassis dynamics are modeled using relevant fundamental laws taking into account aerodynamic effects and road slop variation. The longitudinal slip, resulting from tire deformation, is captured through Kiencke's model. A highly nonlinear model is thus obtained and based upon in vehicle longitudinal motion simulation. A simpler, but nevertheless accurate, version of that model proves to be useful in vehicle longitudinal control. For security and comfort purpose, the vehicle speed must be tightly regulated, both in acceleration and deceleration modes, despite unpredictable changes in aerodynamics efforts and road slop. To this end, a nonlinear controller is developed using the Lyapunov design technique and formally shown to meet its objectives i.e. perfect chassis and wheel speed regulation.     

Bi-level Decision-making Modeling for an Autonomous Driver Agent: Application in the Car-following Driving Behavior

ABSTRACT

Road crashes are present as an epidemic in road traffic and continue to grow up, where, according to World Health Organization; they cause more than 1.24 million deaths each year and 20 to 50 million non-fatal injuries, so they should represent by 2020 the third leading global cause of illness and injury. In this context, we are interested in this paper to the car-following driving behavior problem, since it alone accounts for almost 70% of road accidents, which they are caused by the incorrect judgment of the driver to keep a safe distance. Thus, we propose in this paper a decision-making model based on bi-level modeling, whose objective is to ensure the integration between road safety and the reducing travel time. To ensure this objective, we used the fuzzy logic approach to model the anticipation concept in order to extract more unobservable data from the road environment. Furthermore, we used the fuzzy logic approach in order to model the driver behaviors, in particular, the normative behaviors. The experimental results indicate that the decision to increase in velocity based on our model is ensured in the context of respecting the road safety.     

Transboundary pollution,R&;D spillovers and international trade

We consider a non-cooperative and symmetric three-stage game played by two regulator-firm hierarchies. We show that R&D spillovers and the competition of firms on the common market help non-cooperating countries to better internalize transboundary pollution. Surprisingly, international competition increases the per-unit emission-tax and decreases the per-unit R&D subsidy. It also leads to a higher investment in R&D and production, and to a lower emission ratio. In most cases, pollution in common market is lower than in autarky, implying a greater social welfare, and the contrary occurs in some other cases.