Cardiovascular diseases (CVDs) are the primary cause of death in the world. The development of easy-to-use and non-invasive monitoring and predicting CVDs' diagnosis methods is crucial. Among the key parameters in the cardiovascular system is the arterial stiffness. An increase in arterial stiffness is considered a primary risk factor for CVDs. Although arterial stiffness can be assessed non-invasively by measuring the carotid-to-femoral pulse wave velocity (cf_PWV), which is considered as a gold standard for arterial stiffness measurement, the clinical process of assessing this parameter is very intrusive and complicated. In this work, we propose an artificial intelligence-based method for the prediction of (PWV) non-invasively using distal photoplethysmogram PPG waveforms. Functionally, PPG offers a simple, reliable, low-cost technique to measure blood volume change and hence assess the cardiovascular function. Here, we identify features from the timings of fiducial points that are extracted from the PPG, its first, second, and third derivative waveforms. The results based on virtual data-set show an acceptable estimation of the arterial stiffness index, carotid-to-femoral pulse wave velocity with mean absolute percentage error less than 2.5%.

The novel coronavirus disease (COVID-19) is known as the causative virus of outbreak pneumonia initially recognized in the mainland of China, late December 2019. COVID-19 reaches out to many countries in the world, and the number of daily cases continues to increase rapidly. In order to simulate, track, and forecast the trend of the virus spread, several mathematical and statistical models have been developed. Susceptible-Exposed-Infected-Quarantined-Recovered-Death-Insusceptible (SEIQRDP) model is one of the most promising dynamic systems that has been proposed for estimating the transmissibility of the COVID-19. In the present study, we propose a Fractional-order SEIQRDP model to analyze the COVID-19 epidemic. The Fractional-order paradigm offers a flexible, appropriate, and reliable framework for pandemic growth characterization. In fact, fractional-order operator is not local and consider the memory of the variables. Hence, it takes into account the sub-diffusion process of confirmed and recovered cases growth. The results of the validation of the model using real COVID-19 data are presented, and the pertinence of the proposed model to analyze, understand, and predict the epidemic is discussed.

Impact Statement: Two element fractional-order Windkessel model provides a new simplified and flexible tool for aortic input impedance estimation, offering a pioneering way for a better understanding of vascular mechanical properties.

Goal: Fractional-order Windkessel model is proposed to describe the aortic input impedance. Compared with the conventional arterial Windkessel, the main advantage of the proposed model is the consideration of the viscoelastic nature of the arterial wall using the fractional-order capacitor (FOC).

Methods: The proposed model, along with the standard two-element Windkessel, three-element Windkessel, and the viscoelastic Windkessel models, are assessed and compared using in-silico data.

Results: The results show that the fractional-order model fits better the moduli of the aortic input impedance and fairly approximates the phase angle. In addition, by its very nature, the pseudo-capacitance of FOC makes the proposed model's dynamic compliance complex and frequency-dependent.

Conclusions: The analysis of the proposed fractional-order model indicates that fractional-order impedance yields a powerful tool for a flexible characterization of the arterial hemodynamics.

In this letter, a memristor-based chirp pulse generator cir- cuit is introduced for Ultra-Wideband transceivers for the first time. The proposed generator is built using memristor- controlled ring oscillator. Memristor is used to replace the bulky components in the chirp pulse generation such as sur- face acoustic wave filters and reactive components (capac- itor and inductors) which reflects a huge reduction in area and power. The chirp pulse frequency of the proposed cir- cuit varies linearly with time over the pulse duration due to the change in the memristance. The proposed circuit is mathematically analyzed and designed using 65-nm CMOS technology. The 500-MHz bandwidth is demonstrated using a 32 ns pulse width complying with the FCC regulations. The power consumption is 84 μW with a 10 MHz pulse repeti- tion frequency (PRF).

Arterial system is completely coupled with the heart, such that the contractile state of the left ventricle and its produced central blood pressure (the pressure in the aorta) are in tune with the arterial mechanical properties. This study investigates the use of fractional-order capacitor and resistor elements to expose, and estimate the main arterial mechanical properties. We propose a simple two-element fractional-order Windkessel model that is able to capture the real aortic impedance dynamic for different cardiac physiological states. To perform a quantitative validation, in-silico ascending aortic blood pressure and flow database of 3,325 virtual subjects was used. The proposed model provides new simplified tool for "hemodynamic problem" solving, offering a pioneer way for a better understanding of vascular mechanical properties dependency on hemodynamic changes such as arterial viscoelasticity.

In this paper, a new fractional order generalization of the classical Windkessel arterial model is developed to describe the aortic input impedance as an assessment of the left ventricular after-load. The proposed models embeds fractional-order capacitor to describe the total arterial compliance. In this paper, we report our investigations on fractional calculus tools and demonstrate that fractional-order impedance can be used to determine the vascular properties and studying its dynamic effects. We conceived two fractional-order lumped parametric models: the fractional-order two-element Windkessel model and the fractional-order three-element Windkessel model. We compared these models to the classical Windkessel one using in-silico ascending aortic blood pressure and flow database of 3325 virtual subjects. Results showed that the proposed fractional-order models overcame the limitations of the standard arterial Windkessel model and captured very well the real dynamic of the aortic input impedance modulus. We also demonstrated that the proposed models could monitor the changes in the aortic input impedance for various arterial physiological states. Therefore, our models provide a new tool for" hemodynamic inverse problem" solving and offer a new, innovative way to better understand the viscoelastic effect, in terms of resistive behavior of the arterial motions.

Cardiovascular diseases are deemed to be the underlying source of mortality globally. Modeling the systemic arterial system is of a vital importance in the diagnosis and assessment of cardiac pathophysiology. In this work, we explore the fractional viscoelastic properties of the arterial blood vessel, and present a fractional-order lumped parameter model. We refer to this model as arterial fractional order visco-elastic (AFV) model. A novel feature of this characterization is that the ideal analog parameter displaying the arterial compliance in the well-known windkessel model, has been replaced by a fractional order element (Fractional Capacitor). It displays the complex and frequency dependent total arterial compliance by combining both resistive and capacitive properties that exhibit the fractional viscoelastic behavior of the vessel wall. The contribution of both characteristics is controlled by a fractional differentiation …

Arterial hemodynamic assessment has always been essential for clinical Cardiovascular System (CVS) diagnosis. Using Windkessel (WK) lumped parametric model as non-invasive measurement tool provides the potential of achieving a very convenient, computational inexpensive and accurate prediction of the arterial parameters. Many versions of WK models have been proposed and extensively studied, over the last century. In general, they can be classified into two categories: elastic and viscoelastic models. Recently, several studies have discussed the potential of describing the arterial wall viscoelasticity using fractional order models, reducing the number of parameters and exposing a natural response. Hence, a key missing item in the arterial Windkessel modeling is a fractional-order analog component that can provide a reliable, realistic and reduced representation of the fractional viscoelasticity behavior …

Current reference circuits are widely used in analog integrated circuit design. However, due to PVT and aging variations, the reference currents are mostly affected which requires reprogramming the reference circuit. Recently, memristors are investigated in many analog applications due to the programmability and non-volatility. In this paper, we introduce a simple programmable memristor-based circuit that can be used in current reference generators. The circuit is based on one memristor and one CMOS transistor to tune the resistance of the memristor. VTEAM memristor model is used to study the proposed circuit programmability. The necessary tuning conditions for the circuit are discussed. Then, the proposed circuit have been used in the well-known Beta-Multiplier current reference to generate a programmable current reference. The designed circuit has a reasonable current tuning range due to the limited …

Associate and approximate computing using resistive memory based Ternary Content Addressable Memory is becoming widely used. In this paper, a simplified model based analysis of a 2T2M-Ternary Content Addressable Memory using memristors is introduced. A comprehensive study is presented taking into consideration different circuit parameters and parasitic effects. Parameters such as the memristor R_h/R_l ratio, transistor technology, operating frequency, and memory width are taken into consideration. The proposed model is verified with SPICE showing a high degree of matching between theory and simulation. The utility of the model is established using a design example.

Arterial hemodynamic assessment has always been essential for clinical Cardiovascular System (CVS) diagnosis. Using Windkessel (WK) lumped parametric model as non-invasive measurement tool provides the potential of achieving a very convenient, computational inexpensive and accurate prediction of the arterial parameters. Many versions of WK models have been proposed and extensively studied, over the last century. In general, they can be classified into two categories: elastic and viscoelastic models. Recently, several studies have discussed the potential of describing the arterial wall viscoelasticity using fractional order models, reducing the number of parameters and exposing a natural response. Hence, a key missing item in the arterial Windkessel modeling is a fractional-order analog component that can provide a reliable, realistic and reduced representation of the fractional viscoelasticity behavior …

MTCAM (Memristor Ternary Content Addressable Memory) is a special purpose storage medium in which data could be retrieved based on the stored content. Using Memristors as the main storage element provides the potential of achieving higher density and more efficient solutions than conventional methods. A key missing item in the validation of such approaches is the wide spread availability of hardware emulation platforms that can provide reliable and repeatable performance statistics. In this paper, we present a hardware MTCAM emulation based on 2-Transistors-2Memristors (2T2M) bit-cell. It builds on a bipolar memristor model with storing and fetching capabilities based on the actual current-voltage behaviour. The proposed design offers a flexible verification environment with quick design revisions, high execution speeds and powerful debugging techniques. The proposed design is modeled using …