Wyniki wyszukiwania - BazTech

1

Passive Mixer-based UWB Receiver with Low Loss, High Linearity and Noise-cancelling for Medical Applications

Kareem Thaar A., Trabelsi Hassen

International Journal of Electronics and Telecommunications

|

2023

|

Vol. 69, No. 1

61--67

EN

A double balanced passive mixer-based receiver operating in the 3-5 GHz UWB for medical applications is described in this paper. The receiver front-end circuit is composed of an inductorless low noise amplifier (LNA) followed by a fully differential voltage-driven double-balanced passive mixer. A duty cycle of 25% was chosen to eliminate overlap between LO signals, thereby improving receiver linearity. The LNA realizes a gain of 25.3 dB and a noise figure of 2.9 dB. The proposed receiver achieves an IIP3 of 3.14 dBm, an IIP2 of 17.5 dBm and an input return loss (S11) below -12.5dB. Designed in 0.18μm CMOS technology, the proposed mixer consumes 0.72pW from a 1.8V power supply. The designed receiver demonstrated a good ports isolation performance with LO_IF isolation of 60dB and RF_IF isolation of 78dB.

2

Evaluation of the Effect of Uncertainties on the Acoustic Behavior of a Porous Material Located in a Duct Element Using the Monte Carlo Method

Hannachi Hanen, Trabelsi Hassen, Kani Marwa, Taktak Mohamed, Chaabane Mabrouk, Haddar Mohamed

Archives of Acoustics

|

2023

|

Vol. 48, No. 1

81--91

EN

When studying porous materials, most acoustical and geometrical parameters can be affected by the presence of uncertainties, which can reduce the robustness of models and techniques using these parameters. Hence, there is a need to evaluate the effect of these uncertainties in the case of modeling acoustic problems. Among these evaluation methods, the Monte Carlo simulation is considered a benchmark for studying the propagation of uncertainties in theoretical models. In the present study, this method is applied to a theoretical model predicting the acoustic behavior of a porous material located in a duct element to evaluate the impact of each input error on the computation of the acoustic proprieties such as the reflection and transmission coefficients as well as the acoustic power attenuation and the transmission loss of the studied element. Two analyses are conducted; the first one leads to the evaluation of the impacts of error propagation of each acoustic parameter (resistivity, porosity, tortuosity, and viscous and thermal length) through the model using a Monte Carlo simulation. The second analysis presents the effect of propagating the uncertainties of all parameters together. After the simulation of the uncertainties, the 95% confidence intervals and the maximum and minimum errors of each parameter are computed. The obtained results showed that the resistivity and length of the porous material have a great influence on the acoustic outputs of the studied model (transmission and reflection coefficients, transmission loss, and acoustic power attenuation). At the same time, the other physical parameters have a small impact. In addition, the acoustic power attenuation is the acoustic quantity least impacted by the input uncertainties.

3

Consideration of the uncertainty in the dimensioning of a gearbox of a wind turbine

Trabelsi Hassen, Guizani Amir, Barkallah Maher, Hammadi Moncef, Hadrich Ayman

Journal of Theoretical and Applied Mechanics

|

2021

|

Vol. 59 nr 1

67--79

EN

The paper deals with the design approach of a subdefinite mechatronic system and focuses on the sizing stage of a gearbox of a wind turbine based on the interval computation method. Indeed, gearbox design variables are expressed by intervals to take into account the uncertainty in the estimation of these parameters. The application of the interval computation method allows minimizing the number of simulations and enables obtaining a set of solutions instead of a single one. The dynamic behavior of the gearbox is obtained using the finite element method. The challenge here is to get convergent results with intervals that reflect the efficiency of the applied method. Thus, several mathematical formulations have been tested in static study and evaluated in the case of a truss. Then the interval computation method was used to simulate the behavior of the wind turbine gearbox.

4

Consideration of uncertainties in the preliminary design case of an electromagnetic spindle

Trabelsi Hassen, Guizani Amir, Tounsi Dhouha, Hammadi Moncef, Barkallah Maher, Haddar Mohamed

Journal of Theoretical and Applied Mechanics

|

2019

|

Vol. 57 nr 4

821--832

EN

Modeling and evaluation of uncertainties constitute indeed one of the key points when making any decision. For this, designers have to compare the measured or calculated value with a range of permissible values in order to obtain a guaranteed design process. Thus, in this work, simulation of the dynamic behavior of an electromagnetic spindle was done based on the interval computation technique. Indeed, the use of this technique makes it possible to obtain a set of values for different design parameters of the spindle and, consequently, to avoid making several simulations which could make the system useless, expensive or ineffective. The proposed model is based on the combination of Matlab with ModelCenter. Matlab was used to model and simulate the system and ModelCenter to perform parametric studies to verify the influences of uncertainty on the dynamic behavior of the electromagnetic spindle and to determine the optimal design parameters.