2D electronics based on graphene field effect transistors: tutorial for modelling and simulation

This paper provides modeling and simulation insights into field-effect transistors based on graphene (GFET), focusing on the devices’ architecture with regards to the position of the gate (top-gated graphene transistors, back-gated graphene transistors, and top-/back-gated graphene transistors), substrate (silicon, silicon carbide, and quartz/glass), and the graphene growth (CVD, CVD on SiC, and mechanical exfoliation). These aspects are explored and discussed in order to facilitate the selection of the appropriate topology for system-level design, based on the most common topologies. Since most of the GFET models reported in the literature are complex and hard to understand, a model of a GFET was implemented and made available in MATLAB, Verilog in Cadence, and VHDL-AMS in Simplorer—useful tools for circuit designers with different backgrounds. A tutorial is presented, enabling the researchers to easily implement the model to predict the performance of their devices. In short, this paper aims to provide the initial knowledge and tools for researchers willing to use GFETs in their designs at the system level, who are looking to implement an initial setup that allows the inclusion of the performance of GFETs.This research was funded by PTDC/EEI-TEL/29670/2017—(POCI-01-0145-FEDER-029670); co-financed by the European Regional Development Fund (ERDF), and through COMPETE 2020, by grant SFRH/BD/137529/2018

Study and Design of Reconfigurable Wireless and Radio- Frequency Components Based on RF MEMS for Low-Power Applications

This chapter intends to deal with the challenging field of communication systems known as reconfigurable radio-frequency systems. Mainly, it will present and analyze the design of different reconfigurable components based on radio-frequency microelectromechanical systems (RF MEMS) for different applications. This chapter will start with the description of the attractive properties that RF MEMS structures offer, giving flexibility in the RF systems design, and how these properties may be used for the design of reconfigurable RF MEMS-based devices. Then, the chapter will discuss the design, modeling, and simulation of reconfigurable components based on both theoretical modeling and well-known electromagnetic computing tools such as ADS, CST-MWS, and HFSS to evaluate the performance of such devices. Finally, the chapter will deal with the design and performance assessment of RF MEMS-based devices. Non-radiating devices, such as phase shifter and resonators, which are very important components in the hardware RF boards, will be addressed. Also, three types of frequency reconfigurable antennas, for the three different applications (radar, satellite, and wireless communication), will be proposed and evaluated. From this study, based on theoretical design and electromagnetic computing evaluation, it has been shown that RF MEMS-based devices can be an enabling solution in the design of the multiband reconfigurable radio-frequency devices

Metamaterial vivaldi antenna array for breast cancer detection

The objective of this work is the design and validation of a directional Vivaldi antenna to detect tumor cells’ electromagnetic waves with a frequency of around 5 GHz. The proposed antenna is 33% smaller than a traditional Vivaldi antenna due to the use of metamaterials in its design. It has an excellent return loss of 25 dB at 5 GHz and adequate radiation characteristics as its gain is 6.2 dB at 5 GHz. The unit cell size of the proposed metamaterial is 0.058λ × 0.054λ at the operation frequency of 5 GHz. The proposed antenna was designed and optimized in CST microwave software, and the measured and simulated results were in good agreement. The experimental study demonstrates that an array composed with the presented antennas can detect the existence of tumors in a liquid breast phantom with positional accuracy through the analysis of the minimum amplitude of Sii.FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/202

Corrosion behaviour of steel rebar: effect of simulated concrete pore solution and chloride ions

In this work, we investigate the corrosion behavior of steel rebar (SR) in four simulated concrete pore solutions (CPS): NaOH+KOH (CPS1), Na2CO3 (CPS2), NaOH (CPS3) and Ca(OH)2 (CPS4) medium.  Effect of addition of Cl- anions as pollutant on pitting and uniform corrosion of SR is investigated by using potentiodynamic polarization (PDP) technic. The result obtained show that uniform and pitting corrosion of SR are strongly influenced by the nature of simulated CPS. In unpolluted CPS’s, only uniform corrosion of SR is observed in all cases. SR has excellent corrosion resistance in CPS4 compared to the other simulated CPS. In the polluted CPS’s by Cl- anions, we observe an accelerated uniform corrosion especially in CPS1, CPS3 and CPS4 mediums. The sensitivity to localized corrosion of SR varies from one simulated environment to another. It has the best resistance to pitting corrosion in polluted CPS3 medium. In CPS1 (pH = 13) and CPS2 (pH = 11.6) polluted by 3% NaCl, the tendency to pitting corrosion is the same. The localized attack is more pronounced in polluted CPS4 (pH=12.7). These results demonstrate that there are no limit values of the pH and the content of Cl- ions for the initiation of pitting and / or uniform corrosion. Therefore, it is the chemical composition of the simulated medium which imposes the pH value and the Cl- content for systematic corrosion study of the SR in the simulated CPS

Synthesis, Empirical and Theoretical Investigations on New Histaminium Bis(Trioxonitrate) Compound

In this paper, a novel hybrid material, entitled histaminium bis(trioxonitrate), with the general chemical formula (C5H11N3)(NO3)2, denoted by HTN was presented. Single-crystal X-ray diffraction was used to determine the structural characteristics of this compound after it was made using a slow evaporation method at room temperature. This compound was elaborated and crystallized to the monoclinic system with space group P21/c, and the lattice parameters obtained were: a = 10.4807 (16)Å, b = 11.8747 (15)Å, c = 16.194 (2)Å, β = 95.095 (6)°, V = 2007.4 (5)Å3 and Z = 8. The title compound’s atomic structure couldbe modeled as a three-dimensional network. Organic cations and nitrate anions were connected via N–H...O and C–H...O hydrogen bonds in the HTN structure. The intermolecular interactions responsible for the formation of crystal packing were evaluated using Hirshfeld surfaces and two-dimensional fingerprint plots. The compound’s infrared spectrum, which ranged from 4000 to 400 cm−1, confirmed the presence of the principal bands attributed to the internal modes of the organic cation and nitrate anions. Additionally, spectrofluorimetry and the ultraviolet–visible spectrum was used to investigate this compound. DFT calculations were used to evaluate the composition and properties of HTN. The energy gap, chemical reactivity and crystal stability of HTN were quantified by performing HOMO-LUMO frontier orbitals analysis. Topological analysis (AIM), Reduced Density Gradient (RDG), molecular electrostatic potential surface (MEPS) and Mulliken population were processed to determine the types of non-covalent interactions, atomic charges and molecular polarity in detail

Applicability and effectiveness of the park and ride system for Kandy city

Kandy is the main city in Kandy district and Central province of Sri Lanka. As a result of increased car ownership with increase of income level among other reasons, modal share of public transport has decreased over the years. This will increase congestion of roads, reduction of mobility and reliability. One possible option is to reduce the private vehicle users to public transport modes or combination of both private vehicles with public transport mode. “Kandy City Transport Study, (KCTS)” and “Kandy Transport Improvement Program, (KTIP)” have proposed strategic plans to improve transportation system in Kandy city. Furthermore three Satellite Stations were proposed at Getambe, Katugasthota and Thennakumbura with Kandy Multimodal Transport Terminal. In this research, applicability and effectiveness of the park and ride system to Kandy city was studied. Recent studies found that 59.5% of passenger vehicles’ trips end are in Kandy CBD. Willingness to use of park and ride system among private vehicle users were assessed through questionnaire. Questionnaire was mainly focused on traveler’s background information, travel behavior data, satisfaction of present transport mode and important factors for better Park and Ride system. Trip information data and other information given by the responders were analyzed through the statistical methods. Finally acceptability of the proposed Park and Ride system was analyzed with monthly income level, average travel time, average trip length, expected waiting time on average journey and average walking distance from point of egress from the public transport mode. According to the results, acceptability of the proposed Park and Ride system mainly depends on present mode of transport, monthly income level and travel time. Travel distance, waiting time and average walking distance from the point of the egress from the public transport to destination are independent with acceptability of the proposed Park and Ride system. The most of responders were not satisfied with the current travel time, pedestrian walkways. Responders are expecting comfortable public transport system with high frequency for successful proposed Park and Ride system in Kandy city

Modelling, design and fabrication of a novel reconfigurable ultra-wide-band impedance matching based on RF MEMS technology

This study proposes an adaptive impedance-matching network with tremendously reduced dimensions and presents its fabrication process. The proposed radio-frequency micro-electromechanical system (RF MEMS) device is based on a coplanar waveguide design and relies on suspended bridges for impedance tuning. The tuning is controlled by a variable applied DC voltage to the bridges. Preliminary tests validate the device's operation mechanism, and simulations were performed on both the mechanical aspects of the device (bridge gap manipulation) and tuning capabilities. This device presents the possibility of operating in a wide band of frequencies, namely [1-6] GHz, and for load impedances in the interval of [30-90] omega for the real part and [-10-30] for the imaginary part. The device's resonant frequency and its bandwidth can be modified easily by changing the bridge gap in the RF MEMS.This work was supported by the Laboratory of Circuit and Electronic System in High Frequency of University of Tunis El Manar and Research Center for Microelectromechanical Systems (CMEMS) of the University of Minho Braga, Portugal. Foundation for Science and Technology (FCT) project PTDC/EEI-TEL/5250/2014, by FEDER funds through POCI-01-145-FEDER-16695 and Projecto 3599-Promover a Produção Científica e Desenvolvimento Tecnológico e a Constituição de RedesTemáticas, and by grant SFRH/BD/116554/2016

Breast cancer detection based on CPW antenna

This work presents the design of CPW antenna for microwave tumor cell detection. The simulation results of the antenna performance in free space using CST-MWS are shown at 4.5 GHz. In order to study, the influence of the antenna movement on its electrical properties during breast cancer diagnosis, the CPW antenna is placed at a distance of 32 mm from the surface of the breast phantom with and without tumor cells by using different positions of the antenna to cover the entire breast surface and with various cross sections of the breast phantom. The tumor is represented by the sphere of diameter equal to 10 mm. In this paper, three interesting antenna parameters are analyzed, the return loss, the radiation pattern and the E-field inside the breast. This study shows good results to can detect the incidence of the tumor at 4 GHz. Comparing these results without and with tumor, it can be said that increasing the angle between the antenna and the breast phantom (from 0° to 60°), the return loss increases from -17 dB to -19.34 dB in 0°, from -15.37 dB to -19.28 dB in 30° and from -12.18 dB to -15.44 dB in 60°. The gain increases from 4.22 dB to 4.26 dB in 0°, from 1.13 dB to 1.2 dB in 30° and from 3.91 dB to 4.06 dB in 60°. In addition, to the increase of the e-field values inside the different cross sections of the breast phantom.(undefined