Papers by Farid Golnaraghi
Journal of electrical bioimpedance, 2015
The present study determines the effect of compression over bioimpedance of healthy soft tissue (... more The present study determines the effect of compression over bioimpedance of healthy soft tissue (in-vitro and in-vivo). Electrical impedance spectroscopy (EIS) is a promising tissue characterization and tumor detection technique that uses tissue impedance or admittance to characterize tissue and identify tissue properties as well as cell structure. Variation in EIS measurements while applying pressure suggests that compression tends to affect soft tissue bioimpedance. Moreover, the displacements in tissue caused by applied compression may provide useful information about the structure and state of the tissue. Thus combining the changes to the electrical properties of tissue resulted by applied compression, with the changes in tissue displacements caused by applied compression, and consequently measuring the effect that electrical and mechanical properties have on each other, can be useful to identify tissue structure. In this study, multifrequency bioimpedance measurements were performed on in-vitro and invivo soft tissue at different pressure levels. Increasing compression on the in-vitro tissue results in an increase in both extracellular resistance and membrane capacitance while it causes a reduction in the intracellular resistance. However, as the compression over the in-vivo samples increases, the intracellular and extracellular resistance increase and the membrane capacitance decreases. The in-vivo measurements on human body are also tested on contralateral tissue sites and similar tissue impedance variation trends are observed in the contra-lateral sites of human body. The evidence from these tests suggests the possibility of using this EIS-Pressure combined measurement method to improve tumor detection in soft tissue. Based upon the observations, the authors envision developing an advanced model based upon the Cole model, which is dependent on tissue displacements.
Journal of Medical and Biological Engineering, Aug 3, 2019
Purpose Tissue classification based upon tissue stiffness is very useful in early diagnosis of ca... more Purpose Tissue classification based upon tissue stiffness is very useful in early diagnosis of cancer; specifically, breast tissue health is diagnosed through tissue stiffness. This paper proposes a method to define the mechanical characteristics of various soft tissues, which could be helpful in discovery of soft tissue abnormalities. Methods This study focused on tissue characterization and the identification of the relationship between tissue properties and pathological mechanics using an elastography technique (method of cancer detection, that uses the response of soft tissue to deformation) based on the Yeoh hyper-elastic model. The suitability of the Yeoh model was validated through compression testing of breast phantoms, animal tissues, and in vivo human tissues. Results The mean deviation between the known and calculated position was 0.31 ± 0.16 mm. The maximum deviation was less than 0.86 mm. Conclusion The results indicate that the location of a scintillator within the recording cage imaged with two cameras can be calculated with submillimeter accuracy. We hope that our methods can be applied to improve automatic (even real-time) tracking of various animals in vivo.
CMBES Proceedings, May 20, 2014
Both Frequency-Domain Diffuse Optical Tomography (FD-DOT) and Electrical Impedance Spectroscopy (... more Both Frequency-Domain Diffuse Optical Tomography (FD-DOT) and Electrical Impedance Spectroscopy (EIS) are mature and developed technologies that have been used separately for breast cancer detection. In this paper we have developed and present a handheld diffuse optical tomography probe combined with EIS to monitor, non-invasively, real time biological tissue activity in vivo. The proposed probe has two near-infrared wavelengths LEDS (capsulated in one package) and one photodiode, and two Ag/AgCl electrodes. Using FD-DOT with multispectral evaluation algorithm, we can measure Tissue Oxygenate Index (TOI), change of TOI, Tissue Oxygenate Hemoglobin (TOH) and Tissue Deoxygenate Hemoglobin (TDH) as well as determine the concentrations of water, lipids and optical scattering properties in normal and cancerous breast tissue. The EIS provides information regarding electrical properties of tissue specifically increased cellular water, sodium content, altered membrane permeability, and changed packing density and orientation of cells. The two point EIS is capable of a frequency sweep from 1 Hz to 50 MHz, but to overcome skin impedance and electrode polarization issues, the 100KHZ to 1MHZ frequency range has been considered for the present study. The combined FDOT-EIS system is used to provide simultaneous electrical as well as optical characteristics of invivo tissue.
CMBES Proceedings, May 20, 2014
In this paper a systematic while practical methodology has been presented for design of vehicle's... more In this paper a systematic while practical methodology has been presented for design of vehicle's semiactive suspension systems. The semi-active control strategies developed to improve vehicle ride comfort and stability generally have a switching nature. This makes the design of the controlled suspension systems difficult and highly dependent on an extensive trial and error process. The proposed methodology maps the discontinuous control system model to a continuous linear region where all the time/frequency design techniques established in the conventional control system theory can be applied. If the semiactive control system is designed to satisfy some ride/stability requirements, an inverse mapping offers control law. The effectiveness of the proposed design methodology in dealing with real industrial problems is demonstrated with experimental results.
Journal of Vibration and Control, Sep 23, 2011
This paper describes the design of a versatile and fully controllable active engine mount. The pr... more This paper describes the design of a versatile and fully controllable active engine mount. The proposed active mount is capable of addressing vibration isolation requirements at various driving conditions. This design addresses a better ride quality that has always been demanded by the automotive industry, as well as satisfying sophisticated vibration isolation requirements for the unconventional engines, i.e. variable displacement, and hybrids. The proposed engine mount replaces the decoupler of the original design with a solenoid actuator. The mathematical model of the active mount is obtained. The dynamic characteristics of the mount are shown to be highly controllable over the operating frequency range of excitation in engines. The effectiveness of the developed active engine mount for various working conditions of engine is also evaluated. Several driving conditions are investigated and proper control strategies are utilized to demonstrate the mount's capability to fulfill the isolation requirements for each condition. The promising results, in addition to compactness, low cost, fail safety, and durability are the main advantages of the proposed active engine mount, which makes it viable for automotive applications.
2013 Fourth International Conference on Computing, Communications and Networking Technologies (ICCCNT), Jul 1, 2013
ABSTRACT There is an associated position uncertainty while determining the position of a handheld... more ABSTRACT There is an associated position uncertainty while determining the position of a handheld diagnostic probe used to detect anomaly present in tissue; this uncertainty is overcome by finding the position and orientation of the diagnostic probe with respect to a reference. A diagnostic probe determines various anatomical parameters but the obtained results are not associated with a position to be compared in time domain. Time domain comparison of anatomical changes helps in pathological findings. For differential comparison, relative position of data collection point with respect to the patient position needs to be the same on different examination days. This paper presents an overview on the work done in overcoming this uncertainty of the position in a hand held probe with respect to the human body. A cost-effective binocular vision system is used to help provide the position information; the method consists of using reference markers and tracking the position and orientation of these reference markers present on the probe. The paper introduces a 3-D stereo imaging technique to determine position of the data collecting point in real time and reconstruct the surface of the patient phantom. The associated error in position determination has been close to 2.5 mm. Yet not clinically tested, this tracking system can be used as a cost effective solution to determine diagnostic hand held probe position information for differential comparison; by installing two to four digital cameras in the examination room.
Knowledge Based Systems, Aug 1, 2010
A novel neural fuzzy (NF) mapping framework is developed in this paper to convert linear systems ... more A novel neural fuzzy (NF) mapping framework is developed in this paper to convert linear systems and a class of nonlinear systems from the crisp-domain to a NF representation. The resulting neural fuzzy system (NFS) is guaranteed to be functionally identical to the original system. Therefore, the proposed mapping technique provides a well-defined prototype for one type of NFS design. The resulting fuzzy reasoning representation facilitates the investigation in linguistic terms into the system operations, whereas the system performance can be further improved by properly incorporating expertise knowledge or by online/offline training via this NF structure. The developed technique is to extend our previously-developed techniques to NF modeling/mapping applications and its effectiveness is demonstrated by simulations using a flexible-link robot.
In this paper a simple formulation of dynamic model of a turboprop installations has been present... more In this paper a simple formulation of dynamic model of a turboprop installations has been presented incorporating aerodynamic forces. A four-bladed propeller-engine is simplified to have six rigid-body degrees of freedom. The engine is connected to the nacelle through resilient elements in order to reduce vibration transmission from the engine to the airplane structure. The aerodynamic forces acting on the propeller are modeled utilizing quasi-steady airfoil theory by considering their effect as reaction forces. Using the formulated dynamic model, an analysis of the stability of the engine-mount is conducted by deriving a second order eigenvalue problem. The system natural frequencies are found to be dependent on the rotational speed. At lower speeds, the aerodynamic forces have a stabilizing effect on the system. At higher rotational frequencies, the engine reaches a speed after which the system becomes unstable. The use of soft resilient mounts maximizes the vibration isolation but lowers instability threshold speed.
Vehicle System Dynamics, May 1, 2010
CMBES Proceedings, Jun 15, 2010
arXiv (Cornell University), Jan 7, 2017
We are presenting the design and the preliminary numerical and experimental analyses of two misma... more We are presenting the design and the preliminary numerical and experimental analyses of two mismatched Coriolis vibratory gyroscopes incorporating nonlinear modal interaction. A novel double-H design includes two clamped-clamped beams and a suspended mass in the middle connected to the base beams via four short cantilevers. Another design is a T-shaped gyro including a primary doubly-clamped beam and a secondary sense beam. A combination of analytical, finite element, and experimental analyses are employed to study the characteristics of the nonlinear gyro. The drive mode matches the structure's second mode, while the sense mode matches the fundamental mode of the structure. Our preliminary study indicates that the bandwidth and the sensitivity of the rotation rate sensor are improved by employing the nonlinear modal interaction.
The author has further granted permission to Simon Fraser University to keep or make a digital co... more The author has further granted permission to Simon Fraser University to keep or make a digital copy for use in its circulating collection (currently available to the public at the "Institutional Repository" link of the SFU Library website <www.lib.sfu.ca> at: <http://ir.lib.sfu.ca/handle/1892/112>) and, without changing the content, to translate the thesis/project or extended essays, if technically possible, to any medium or format for the purpose of preservation of the digital work. The author has further agreed that permission for multiple copying of this work for scholarly purposes may be granted by either the author or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without the author's written permission. Permission for public performance, or limited permission for private scholarly use, of any multimedia materials forming part of this work, may have been granted by the author. This information may be found on the separately catalogued multimedia material and in the signed Partial Copyright Licence. While licensing SFU to permit the above uses, the author retains copyright in the thesis, project or extended essays, including the right to change the work for subsequent purposes, including editing and publishing the work in whole or in part, and licensing other parties, as the author may desire.
Rolling-element bearings are widely used in various mechanical and electrical systems. A reliable... more Rolling-element bearings are widely used in various mechanical and electrical systems. A reliable online bearing fault diagnostic technique is critically needed in industries to detect the occurrence of a fault so as to prevent system's performance degradation and malfunction. To improve the fault diagnostic reliability and efficiency, a genetic algorithm based feature optimization technique is proposed in this work. In this scheme, the discrete wavelet packet analysis is utilized to decompose the raw vibration signal into several constituent signatures, from which the bearing health condition related features are formulated. Taking these features as a fundamental search space, the genetic algorithm based technique is adopted to choose the representative features that carry more discriminatory information for bearing health condition assessment. This optimization process is guided by a suggested fitness function. A neural fuzzy system is utilized for diagnostic classification operations. The performance of the proposed technique is evaluated by experimental tests.
Fuzzy Sets and Systems, Nov 1, 2010
Nonlinear PID and gain scheduling controls have attracted much research interests in recent years... more Nonlinear PID and gain scheduling controls have attracted much research interests in recent years. These control strategies can accommodate some nonlinear characteristics by allowing the gains varied or rescheduled as a function of system states. In this paper, a novel fuzzy ...
Journal of the Acoustical Society of America, Nov 1, 1990
This paper reports on the design, fabrication and rate table characterization of an H-shaped tuni... more This paper reports on the design, fabrication and rate table characterization of an H-shaped tuning fork microresonator with 2:1 internal resonance as an actuation mechanism. The nonlinear principle of operation addresses major challenges in MEMS Coriolis vibratory gyroscopes: eliminating the mode-matching requirement, minimizing instability and drift due to mechanical cross-coupling between the fundamental modes, and generating a wide operating frequency range with high-signal gain and less sensitivity to fluctuations in driving frequency. The rate measurement relies on capturing the half-order subharmonic response of the device while undergoing the angular velocity. The micromachined resonator is fabricated using the MEMS Integrated Design for Inertial Sensors platform offered by Teledyne DALSA Inc. The experimental finding demonstrated the prominent M-shaped nonlinear resonant curves due to a frequency ratio close to 2:1. The microresonator is nominally operated in the overlap region between the forward and backward frequency sweeps, where the signal gain is less sensitive to frequency fluctuations. The microresonator described here operates at 561.23600kHz in a near 2:1 frequency ratio between two anti-phase resonant modes. Experimental rate characterization of the microresonator revealed a linear dynamic range of 220 deg sec-1 with a sensitivity of 0.011 mV deg-1 sec-1 using an 80V DC polarization voltage. The experimental results of the microresonator showed the induced oscillations in the so-called pendulum mode by Coriolis force coupling, despite a clear disparity on natural frequencies of the desired modes.
We are reporting the design and experimental investigation on a microresonator simultaneously exh... more We are reporting the design and experimental investigation on a microresonator simultaneously exhibiting nonlinear modal interactions due to 1/2 subharmonic resonance and 2:1 internal resonance. This has been made possible through careful design of the structure with attention to the limits of microfabricated devices. Finite element models of the structure were built and used to layout the device with two desired vibrational modes with a ∼2:1 frequency ratio. The microresonator was fabricated in MEMS Integrated Design for Inertial Sensors (MIDIS) from Teledyne DALSA Semiconductor Inc. (TDSI). Extensive experiments were conducted to verify the intended nonlinear responses. The device design methodologies can be employed to fabricate various sensors, including nonlinear gyroscopes incorporating 2:1 internal resonance.
In this paper, a new switched-mode bidirectional bridgeless AC/DC converter, operating in the dis... more In this paper, a new switched-mode bidirectional bridgeless AC/DC converter, operating in the discontinuous conduction mode (DCM), for automotive energy harvesting is presented. The simple topology consisting of common source n-MOSFETs allows for direct AC/DC conversion, minimum auxiliary circuits and simple gating patterns, when compared to other AC/DC converters proposed in the literatures. The circuit operation is analyzed and shown that the converter-battery topology can operate as a synthesized variable resistor with regenerative functionality. The circuit is designed for low-power energy harvesting applications; for example, regenerating dissipated power in a vehicle suspension damper by converting vibrational energy into battery charge. Simulation results including various switching waveforms and power conversion efficiency are presented to demonstrate performance of the proposed converter. Experimental results, including power conversion efficiency and resistance synthesis sweep, by connecting the proposed converter to a regenerative vehicle suspension prototype are also included.
Journal of Vibration and Acoustics, Oct 1, 2015
This paper proposes a systematic methodology for predicting and optimizing the performance of an ... more This paper proposes a systematic methodology for predicting and optimizing the performance of an energy regenerative suspension system to efficiently capture the vibratory energy induced by the road irregularities. The method provides a graphical design guideline for the selection of stiffness and damping coefficients aimed at either best ride comfort or maximum energy harvesting. To achieve energy regeneration capability, a low-power electronic circuit capable of providing a variable load resistance is developed and fabricated. The circuit is controlled to provide an adjustable damping coefficient in the real-time. A test-bed is utilized to experimentally verify the proposed techniques. The results indicate that the analytical and simulation results concerning the optimal values for dynamic control and power regeneration match the experimental results.
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Papers by Farid Golnaraghi