Cognitive radio technology would enable a set of secondary users (SU) to opportunistically use the spectrum licensed to a primary user (PU). On the appearance of this PU on a specific frequency band, any SU occupying this band should free it for PUs. Typically, SUs may collaborate to reduce the impact of cognitive users on the primary network and to improve the performance of the SUs. In this paper, we propose and analyze the performance of virtual reservation in collaborative cognitive networks. Virtual reservation is a novel link maintenance strategy that aims to maximize the throughput of

Memristor has become an interesting research subject in the recent years. Its special behavior has attracted the attention of the research community that motivated researchers to investigate it in details. As memristor is a relatively new electrical element, it is not yet available in the market as a solid state component Researchers found their way to build memristor emulators to achieve its pinched hysteresis. While many papers proposed floating emulators, only a few papers presented a grounded one. In this paper, an incremental grounded memristor emulator is proposed. The mathematical model

The spread of epidemics and diseases is known to exhibit chaotic dynamics; a fact confirmed by many developed mathematical models. However, to the best of our knowledge, no attempt to realize any of these chaotic models in analog or digital electronic form has been reported in the literature. In this work, we report on the efficient FPGA implementations of three different virus spreading models and one disease progress model. In particular, the Ebola, Influenza, and COVID-19 virus spreading models in addition to a Cancer disease progress model are first numerically analyzed for parameter

Pulsed wave Doppler ultrasound is commonly used in the diagnosis of cardiovascular and blood flow abnormalities. Doppler techniques have gained clinical significance due to its safety, real-time performance and affordability. This work presents the development of a pulsed wave spectral Doppler module, which was integrated into a reconfigurable ultrasound system. The targeted system adopts a hardware-software partitioning scheme where an FPGA handles the front-end and a PC performs the back-end. Two factors were considered during the design. First, the data transfer rate between hardware and

Due to the fabrication processes, inaccurate manufacturing of the photonic crystals (PCs) might occur which affect their performance. In this paper, we examine the effects of tolerance variations of the radii of the rods and the permittivity of the material of the two-dimensional PCs on their performance. The presented stochastic analysis relies on plane wave expansion method and Mote Carlo simulations. We focus on two structures, namely Si-Rods PCs and Air-Holes PCs. Numerical results show—for both structures—that uncertainties in the dimensions of the PCs have higher impact on its photonic

This paper presents an improved memristor-based relaxation oscillator which offers higher frequency and wider tunning range than the existing reactance-less oscillators. It also has the capability of operating on two positive supplies or alternatively a positive and negative supply. Furthermore, it has the advantage that it can be fully integrated on-chip providing an area-efficient solution. On the other hand, The oscillation concept is discussed then a complete mathematical analysis of the proposed oscillator is introduced. Furthermore, the power consumption of the new relaxation circuit is

In the frame of the development of thin crystalline silicon solar cell technologies, surface nanopatterning of silicon is gaining importance. Its impact on the material quality is, however, not yet fully controlled.We investigate here the influence of surface nanotexturing on the series resistance of a contacting scheme relevant for thin-film crystalline silicon heterojunction solar cells. Twodimensional periodic nanotextures are fabricated using a combination of nanoimprint lithography and either dry or wet etching, while random pyramid texturing is used for benchmarking. We compare these

Building Information Modeling (BIM) has widely become an effective tool in engineering and construction fields. It could be used in: generating shop drawings; detecting clashes; estimating quantities; and controlling documents. Applying BIM technology on bridges is named Bridge Information Modeling (BrIM). Bridge Information Modeling (BrIM) is an intelligent representation of bridges since it contains all information needed about bridges through their whole lifecycle. This paper presents the use of Building Information Modeling in cost and time management of infrastructure bridges. BIM-based

The integration of 2-D periodic nanopattern defined by nanoimprint lithography and dry etching into aluminum-induced crystallization-based polycrystalline silicon thin-film solar cells is investigated experimentally. Compared with the unpatterned cell, an increase of 6% in the light absorption has been achieved thanks to the nanopattern, which, in turn, increased the short-circuit current from 20.6 to 23.8 mA/cm2. The efficiency, on the other hand, has limitedly increased from 6.4% to 6.7%. We show using the transfer length method that the surface topography modification caused by the

In the use of automatic control and its optimization methods, this research discusses how Proportional Integral Derivative (PID) controller is used to provide a smooth auto-parking for an electrical autonomous car. Different tuning methods are shown, discussed, and applied to the system looking forward to enhancing its performance. Time domain specifications are used as a criterion of comparison between tuning methods in order to select the best tuning method to the system with a proper cost function. Results show that Particle Swarm Optimization (PSO) method gives the best results according