The correlation in bone microstructure for ultrasound pulse echo technique is still less accurate compared to through transmission technique. Previous works demonstrated, reflected two modes wave has significant association with bone porosity. The paper aims is to conduct simulation using pulse echo technique to examine the relationship between fast and slow waves with porosity of 2-dimensional cancellous bone models by comparing the result to through transmission technique. The “incident” and “reflected” waves were separated using bandlimited deconvolution method by estimating time threshold of fast and slow waves' transfer function. The parameters of the waves were computed, plotted versus porosity for six different thicknesses and the correlation coefficients between them were compared. The incident and reflected fast wave attenuations show marginally significant correlation with porosity for both bone models orientations. Wave propagation for parallel orientation dominated by incident and reflected fast wave, meanwhile, perpendicular orientation dominated by incident slow wave. The thickness factor affected wave amplitude but less affected the attenuation. Because of propagation loss, reflected wave shows lower correlation to porosity compared to incident wave. Hence, analyzing fast and slow waves might improve the measurement accuracy of pulse echo technique compared to using single mode wave to estimate bone quality.
Microwave Planar Sensor for Determination of the Permittivity of Dielectric M...journalBEEI
This paper proposed a single port rectangular microwave resonator sensor. This sensor operates at the resonance frequency of 4GHz. The sensor consists of micro-strip transmission line and applied the enhancement method. The enhancement method is able to improve the return loss of the sensor, respectively. Plus, the proposed sensor is designed and fabricated on Roger 5880 substrate. Based on the results, the percentage of error for the proposed rectangular sensor is 0.2% to 8%. The Q-factor of the sensor is 174.
Photoacoustic technology for biological tissues characterizationjournalBEEI
The existing photoacoustics (PA) imaging systems showed mixed performance in imaging characteristic and signal-to-noise ratio (SNR). This work presents the use of an in-house assembled PA system using a modulating laser beam of wavelength 633 nm for two-dimensional (2D) characterization of biological tissues. The differentiation of the tissues in this work is based on differences in their light absorption, wherein the produced photoacoustic signal detected by a transducer was translated into phase value that corresponds to the peak amplitude of optical absorption of tissue namely fat, liver and muscle. This work found fat tissue to produce the strongest PA signal with mean ± standard deviation (SD) phase value = 2.09 ± 0.31 while muscle produced the least signal with phase value = 1.03 ± 0.17. This work discovered the presence of stripes pattern in the reconstructed images of fat and muscle resulted from their structural properties. In addition, a comparison is made in an attempt to better assess the performance of the developed system with the related ones. This work concluded that the developed system may use as an alternative, noninvasive and label-free visualization method for characterization of biological tissues in the future.
Design and Implementation of All Optical Tunable Delay by the Combination of ...ijtsrd
In this paper we have designed and implemented an all optical tunable delay element using the combination of wavelength conversion and fiber dispersion. We present wavelength conversion method that show with FWM. The characteristics of the proposed all optical based techniques for tunable delay element are discussed theoretically and demonstrated experimentally. This element operates near 1550nm and generates delay time range is 2430ps. Pyae Phyo Swe | Tin Tin Ohn "Design and Implementation of All-Optical Tunable Delay by the Combination of Wavelength Conversion and Fiber Dispersion" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27874.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/27874/design-and-implementation-of-all-optical-tunable-delay-by-the-combination-of-wavelength-conversion-and-fiber-dispersion/pyae-phyo-swe
My research at Boston University (May 2013)
1. Thesis: Viscoelastic testing and modeling of PDMS micropillars for cellular force measurement
2. Side Projects
1) Conducting polymer actuators
2) PDMS and conducting polymer nanowire composites
3) Silicon oxycarbide thin films
4) Tribological study of DLC coatings
This document describes a study that developed a new paradigm to measure mismatch negativity (MMN) using magnetoencephalography (MEG) in a shorter time. The new paradigm presented tone and phoneme stimuli alternately to the left and right ears with short intervals. This allowed simultaneous measurement of MMN for both stimuli types. Testing the new paradigm on healthy subjects, it produced valid MMN measurements and shortened the testing time to about 20 minutes, compared to 30 minutes for the conventional paradigm. The results validated that the new paradigm could clinically evaluate auditory sensory memory within a limited time.
Andrii Sofiienko - Electron range evaluation and X-ray conversion optimizatio...Andrii Sofiienko
Electron range evaluation and X-ray conversion optimization in tungsten transmission-type targets with the aid of wide electron beam Monte Carlo simulations
A NOVEL APPROACH TO CHANNEL DECORRELATION FOR STEREO ACOUSTIC ECHO CANCELLATI...a3labdsp
This document proposes a novel approach to decorrelating stereo acoustic signals for acoustic echo cancellation based on the psychoacoustic phenomenon of the "missing fundamental". The approach tracks and removes the pitch from one channel of the stereo signal using an adaptive notch filter, which greatly reduces inter-channel coherence in the lower spectrum without affecting signal quality. Experimental results show the proposed approach provides significant coherence reduction and faster convergence speed of adaptive filters compared to a masked noise injection method, while better preserving the stereo quality.
STUDY ON FIBER GRATINGS AND ITS CHARACTERIZATIONDr. Ved Nath Jha
Good potential uses in fiber and fiber lasers have been seen through Random Fiber Gratings (RFGs). However, a quantitative link has never been studied between the RFG's randomness and spectral reaction. This paper first experimentally characterizes two RFGs of varying degrees of randomness by optical frequency reflectometry (OFDR). The high degree of randomness indicates that the grating intensity is limited and the strength variations in spatial domain are large. The experimental findings show. Study establishes the theoretical basis for the optimization configuration and implementation of the long-term fiber grating in the area of fiber optics sensing and communication.
Microwave Planar Sensor for Determination of the Permittivity of Dielectric M...journalBEEI
This paper proposed a single port rectangular microwave resonator sensor. This sensor operates at the resonance frequency of 4GHz. The sensor consists of micro-strip transmission line and applied the enhancement method. The enhancement method is able to improve the return loss of the sensor, respectively. Plus, the proposed sensor is designed and fabricated on Roger 5880 substrate. Based on the results, the percentage of error for the proposed rectangular sensor is 0.2% to 8%. The Q-factor of the sensor is 174.
Photoacoustic technology for biological tissues characterizationjournalBEEI
The existing photoacoustics (PA) imaging systems showed mixed performance in imaging characteristic and signal-to-noise ratio (SNR). This work presents the use of an in-house assembled PA system using a modulating laser beam of wavelength 633 nm for two-dimensional (2D) characterization of biological tissues. The differentiation of the tissues in this work is based on differences in their light absorption, wherein the produced photoacoustic signal detected by a transducer was translated into phase value that corresponds to the peak amplitude of optical absorption of tissue namely fat, liver and muscle. This work found fat tissue to produce the strongest PA signal with mean ± standard deviation (SD) phase value = 2.09 ± 0.31 while muscle produced the least signal with phase value = 1.03 ± 0.17. This work discovered the presence of stripes pattern in the reconstructed images of fat and muscle resulted from their structural properties. In addition, a comparison is made in an attempt to better assess the performance of the developed system with the related ones. This work concluded that the developed system may use as an alternative, noninvasive and label-free visualization method for characterization of biological tissues in the future.
Design and Implementation of All Optical Tunable Delay by the Combination of ...ijtsrd
In this paper we have designed and implemented an all optical tunable delay element using the combination of wavelength conversion and fiber dispersion. We present wavelength conversion method that show with FWM. The characteristics of the proposed all optical based techniques for tunable delay element are discussed theoretically and demonstrated experimentally. This element operates near 1550nm and generates delay time range is 2430ps. Pyae Phyo Swe | Tin Tin Ohn "Design and Implementation of All-Optical Tunable Delay by the Combination of Wavelength Conversion and Fiber Dispersion" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27874.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/27874/design-and-implementation-of-all-optical-tunable-delay-by-the-combination-of-wavelength-conversion-and-fiber-dispersion/pyae-phyo-swe
My research at Boston University (May 2013)
1. Thesis: Viscoelastic testing and modeling of PDMS micropillars for cellular force measurement
2. Side Projects
1) Conducting polymer actuators
2) PDMS and conducting polymer nanowire composites
3) Silicon oxycarbide thin films
4) Tribological study of DLC coatings
This document describes a study that developed a new paradigm to measure mismatch negativity (MMN) using magnetoencephalography (MEG) in a shorter time. The new paradigm presented tone and phoneme stimuli alternately to the left and right ears with short intervals. This allowed simultaneous measurement of MMN for both stimuli types. Testing the new paradigm on healthy subjects, it produced valid MMN measurements and shortened the testing time to about 20 minutes, compared to 30 minutes for the conventional paradigm. The results validated that the new paradigm could clinically evaluate auditory sensory memory within a limited time.
Andrii Sofiienko - Electron range evaluation and X-ray conversion optimizatio...Andrii Sofiienko
Electron range evaluation and X-ray conversion optimization in tungsten transmission-type targets with the aid of wide electron beam Monte Carlo simulations
A NOVEL APPROACH TO CHANNEL DECORRELATION FOR STEREO ACOUSTIC ECHO CANCELLATI...a3labdsp
This document proposes a novel approach to decorrelating stereo acoustic signals for acoustic echo cancellation based on the psychoacoustic phenomenon of the "missing fundamental". The approach tracks and removes the pitch from one channel of the stereo signal using an adaptive notch filter, which greatly reduces inter-channel coherence in the lower spectrum without affecting signal quality. Experimental results show the proposed approach provides significant coherence reduction and faster convergence speed of adaptive filters compared to a masked noise injection method, while better preserving the stereo quality.
STUDY ON FIBER GRATINGS AND ITS CHARACTERIZATIONDr. Ved Nath Jha
Good potential uses in fiber and fiber lasers have been seen through Random Fiber Gratings (RFGs). However, a quantitative link has never been studied between the RFG's randomness and spectral reaction. This paper first experimentally characterizes two RFGs of varying degrees of randomness by optical frequency reflectometry (OFDR). The high degree of randomness indicates that the grating intensity is limited and the strength variations in spatial domain are large. The experimental findings show. Study establishes the theoretical basis for the optimization configuration and implementation of the long-term fiber grating in the area of fiber optics sensing and communication.
Accurate characterizations of material using microwave T-resonator for solid ...TELKOMNIKA JOURNAL
The topic of microwave sensors in enclosures is one of the most active areas in material characterization research today due to its wide applications in various industries. Surprisingly, a microwave sensor technology has been comprehensively investigated and there is an industry demand for an
accurate instrument of material characterization such as food industry, quality control, chemical composition analysis and bio-sensing. These accurate instruments have the ability to understand the properties of materials composition based on chemical, physical, magnetic, and electric characteristics. Therefore, a design of the T-resonator has been introduced
and investigated for an accurate measurement of material properties characterizations. This sensor is designed and fabricated on a 0.787 mm-thickness Roger 5880 substrate for the first resonant frequency to resonate at 2.4 GHz under unloaded conditions. Various standard dielectric of the sample under test (SUT) are tested to validate the sensitivity which making it a promising low-cost, compact in size, ease of fabrication and small SUT preparation for applications requiring novel sensing techniques inquality and control industries.
Analysis and simulations of optimal geometry shapes of the 4 and 9 nano hole ...IJECEIAES
The possibility to limit and manipulate photons at nanometer scales attracted a lot of interest for exciting applications from subwavelength in laser, biosensors, biomedical and optoelectronics devices, the sensor optical properties, however; are complex due to two resonances through propagating and localized surface plasmons. The optical properties of surface plasmons (SPs) at the resonant wavelength is depending on the geometrical nanostructure of materials. In this article, we used different geometry of nanoholes array, 4 and 9 nanoholes array in a metallic film gold nanoparticle with different thickness (20,50,100) nm on SiO2 substrate with refractive index 1.46, we designed two different geometries; 4- holes: hole radius r1=200 nm, period p1=600 nm; and 9- holes: r2=100 nm, period p2=300 nm. Transmission and reflection spectrum have been calculated and simulated by FDTD Lumerical program. From results are observed the effect of thickness is interesting, transmission is increased at (t=20nm) for two arrays. Furthermore, the number of hole and its area has an influence on optical transmission and other parameters (E, H, Ref) which are characteristics of design of metallic nanostructure. We can see that there is a peak value of the wavelength at 519 nm approximately to 73% strong light transmission with 4-NHA in the other hand wavelength of 519 nm transmission is 45% with 9-NHA. strong light transmission is hopeful for many applications (biomedical devices, nanoantennas and laser optical fiber).
Determination of solid material permittivity using T-ring resonator for food ...TELKOMNIKA JOURNAL
In this paper, we present a simple design of a T-ring resonator sensor for characterizing solid detection. The sensor is based on a planar microwave ring resonator and operating at 4.2 GHz frequency with a high-quality factor and sensitivity. An optimization of the T-ring geometry and materials were made to achieve high sensitivity for microwave material characterizations. This technique can determine the properties of solid materials from range of 2 GHz to 12 GHz frequencies. Techniques of current microwave resonator are usually measuring the properties of material at frequencies with a wide range; however, their accuracy is limited. Contrary to techniques that have a narrowband which is normally measuring the properties of materials to a high-accuracy with limitation to only a single frequency. This sensor has a capability of measuring the properties of materials at frequencies of wide range to a high-accuracy. A good agreement is achieved between the simulated results of the tested materials and the values of the manufacturer’s Data sheets. An empirical equation has been developed accordingly for the simulated results of the tested materials. Various standard materials have been tested for validation and verification of the sensor sensitivity. The proposed concept enables the detection and characterization of materials and it has miniaturized the size with low cost, reusable, reliable, and ease of design fabrication with using a small size of tested sample. It is inspiring a broader of interest in developing microwave planar sensors and improving their applications in food industry, quality control and biomedical materials.
This document summarizes research on improving ambiguity resolution in GPS positioning using an ionospheric differential correction model. Data was collected from two stations in Malaysia's equatorial region over a short baseline of 33 km. Applying corrections from an ionospheric model led to ambiguities being resolved faster, in under an hour, compared to uncorrected data which took over 2.5 hours. The model also produced smaller standard errors in baseline positioning and increased the variance ratio and decreased reference variance indicators of successful ambiguity resolution. The findings show that an ionospheric differential correction model can improve ambiguity resolution for single frequency GPS over short baselines.
Tunable and storage potential wells using microring resonator system for bio ...University of Malaya (UM)
The document summarizes a student paper that proposes using a microring resonator system to generate tunable and storage potential wells for trapping and delivering bio-cells or molecules. The system utilizes the concepts of dark solitons and potential wells to introduce trapping forces. It consists of two microring resonators that allow a soliton pulse input to one to propagate and form a resonant output that becomes the input to the second microring resonator. The throughput field can then be controlled and stored by using the resonators, with amplified signals occurring between the left and right nanoring resonators. The technique could potentially be used for applications like transporting plant nutrients for feeding in a similar manner to drug delivery.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
This document presents a new method for detecting corrosion in pipelines based on measuring natural frequencies. The method uses Rayleigh's Law to relate changes in natural frequency to the location and degree of corrosion damage. Finite element models are used to validate the method. The models show that measuring the first and second natural frequencies can accurately determine both where corrosion is located and how severe it is, as indicated by the reduction in bending stiffness. The accuracy depends on having a reasonable estimate of the length of the corroded region. This new natural frequency method provides a simple way to detect pipeline corrosion compared to existing techniques.
Radiation Impedance Of Capacitive Micromachined Ultrasonic TransducersMuhammed N. Senlik
This dissertation analyzes the radiation impedance of capacitive micromachined ultrasonic transducers (cMUTs). It calculates the radiation impedance of a single circular cMUT membrane analytically and using finite element simulations up to the parallel resonance frequency. It then extends this to calculate the radiation impedance of an array of circular cMUT cells arranged in a hexagonal pattern. The radiation impedance is shown to strongly depend on the cell spacing. Higher radiation resistance improves the bandwidth and efficiency of cMUTs. Arranging cells optimizes the radiation resistance for airborne applications.
03 motl lukic_yakovlevelsherbenietal_printedantennadesignspatialpowercombinerCarlos Andres
The document discusses printed antenna designs for broadband waveguide-based spatial power combiners. It investigates the effect of antenna design parameters on bandwidth performance. Meander-slot antennas and their variations are proposed to increase bandwidth and efficiency compared to traditional rectangular patch and slot antennas. Numerical results show interacting single patch and meander slot antennas, as well as arrays of interacting U-strip, U-slot, and meander slot antennas, have advantages in scattering characteristics for spatial power combining applications.
This document summarizes a study that aimed to replicate the results of a previous paper on selectively stimulating neuronal fibers or cell bodies using different asymmetric biphasic current waveforms. The study developed a multi-compartment Hodgkin-Huxley neuronal model in MATLAB and simulated the response of populations of neurons to different stimulus waveforms. The results showed that an anodic-leading asymmetric biphasic waveform selectively activated fibers, while a cathodic-leading waveform preferentially activated cell bodies, consistent with the previous study.
Novel experimental observations in percolative systemsRAVI BHATIA
The presentation in based on interesting experimental results of percolative systems. A weak temperature dependence of conductivity is observed in composite of 0.4 wt %. The coercivity of Fe-MWNT/PS composites varies non-monotonically as a function of MWNT loading.
Transmission spectra of single ring coupled-waveguide resonator configuration...TELKOMNIKA JOURNAL
Development of optical waveguide resonators have greatly expanded and continues to grow since they have kinds potential applications such as wavelength filtering, switching, coupling and multiplexing. One of resonators, coupled waveguides, ring resonators are designed and operated using various coupling configurations. Ring resonators can be particularly used as wavelength filter if the wavelength can fit a whole multiple time in the circumference of the ring. This article proposes to investigate the transmission spectra from the power source and amplify it in linearized ring resonator configurations and varies the input amplitude on five different wavelengths. With finite difference time domain method, the geometry and power source are simulated to obtain the better result and configuration. The results show the intensity phenomena of filtering in optical circuit.
Implementation and analysis of multiple criteria decision routing algorithm f...prjpublications
This document summarizes a research paper that proposes and evaluates a new routing algorithm called Multiple Criteria Decision Routing (MCDR) for wireless sensor networks. MCDR selects the next node to forward data based on both the node's distance to the sink and its remaining energy. The performance of MCDR is compared to flooding algorithm through simulation. Simulation results show that MCDR has better performance than flooding in terms of energy efficiency and fast data delivery.
Mems based optical sensor for salinity measurementprjpublications
1. The document describes a MEMS-based optical sensor using a two-dimensional photonic crystal slab waveguide for measuring salinity.
2. The sensor takes advantage of the fact that the refractive index of sea water changes with salinity concentration. It detects these small refractive index changes by measuring the resulting effective index change in the photonic crystal slab waveguide.
3. Simulation results show that even small refractive index changes due to salinity produce a more significant change in effective index, demonstrating the high sensitivity of the designed sensor. Effective index decreases exponentially with increasing salinity percentage measured.
SUITABLE MOTHER WAVELET SELECTION FOR EEG SIGNALS ANALYSIS: FREQUENCY BANDS D...sipij
Wavelet transform (WT) is a powerful modern tool for time-frequency analysis of non-stationary signals such as electroencephalogram (EEG). The aim of this study is to choose the best and suitable mother wavelet function (MWT) for analyzing normal, seizure-free and seizured EEG signals. Several MWTs can be used, but the best MWT is the one that conserves the quasi-totality of information of the original signal on wavelet coefficients and gather more EEG rhythms in terms of frequency. In this study, Daubechies, Symlets and Coiflets orthogonal families were used as bsis mother wavelet functions. The percentage rootmeans square difference (PRD), the signal to noise ratio (SNR) and the simulated frequencies as the selection metrics. Simulation results indicate Daubechies wavelet at level 4 (Db4) as the most suitable MWT for EEG frequency bands decomposition.Furthermore, due to the redundancy of the extracted features, linear discriminant analysis (LDA) is applied for feature selection. Scatter plot showed that the selected feature vector represents the amount of changes in frequency distribution and carries most of the discriminative and representative information about their classes. Then, this study can provide a reference for the selection of a suitable MWT and discriminativefeatures.
A design and simulation of optical pressure sensor based on photonic crystal ...prjpublications
This document describes the design and simulation of an optical pressure sensor based on photonic crystals in the sub-micron range. Two designs of the pressure sensor are proposed and modeled. The first uses a two-dimensional square lattice photonic crystal with rods in air and a waveguide carved between two dielectric slabs. The second uses a two-dimensional hexagonal lattice photonic crystal with holes in a dielectric slab and a waveguide. Applied pressure moves the upper slab, changing the waveguide dimension and altering the transmission spectrum in a way that corresponds to the pressure level. The designs were simulated using the Finite Difference Time Domain method with the MEEP software tool.
Effect of Material Thickness on Attenuation (dB) of PTFE Using Finite Element...Abubakar Yakubu
This research article examines how the thickness of polytetrafluoroethylene (PTFE) samples affects the attenuation of electromagnetic waves at X-band frequency using finite element method (FEM) simulations. The results show that as the thickness of the PTFE samples increases, the attenuation also increases. Specifically, the 15 mm thick PTFE sample has an attenuation of -3.32 dB, the 30 mm sample has an attenuation of 0.64 dB, and the 50 mm sample has an attenuation of 1.97 dB. The study finds that increasing sample thickness leads to a decrease in electromagnetic wave transmission and an increase in attenuation.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Behavior of Ultrasound Energy in the Presence of ObstacleIRJET Journal
This document discusses using ultrasound energy to detect obstacles embedded within concrete cubes. Ultrasound signals at 50kHz were passed through concrete cubes of varying grade (M20, M30, M40) and size (220mm, 320mm) with and without obstacles like plywood, thermocol, and rods. The ultrasound signal was captured and the energy was calculated using MATLAB. Tables show the area under the energy curve is lower when an obstacle is present, indicating energy absorption. Reinforcement did not significantly affect energy. This method can detect foreign objects in concrete and assess structural health.
Damage detection in cfrp plates by means of numerical modeling of lamb waves ...eSAT Journals
Abstract
The paper presents an application of modeling acoustic waves propagation in a carbon fiber reinforced plastic (CFRP) plates for
damage detection. This task is a part of non-destructive testing (NDT) methods which are very important in many industry
branches. Propagation of Lamb waves is modeled using three-dimensional finite element method by means of commercial
software. In the paper three different cases of plate structures with and without flaws are considered to present review of selected
methods for the detection of defects in time and frequency domain. These are comparisons of: A-scans, B-scans, dispersion
curves, spectrograms, scalograms and energy plots. Developed numerical model first has been validated by means of analytical
solution for isotropic plate.
Keywords: Lamb waves, non-destructive testing, finite element method, damage detection
The document summarizes a study on the effects of human tissue on the performance of a loop antenna. It discusses how the human body, being a lossy dielectric medium, interacts with the near field of antennas. This interaction causes changes to the antenna characteristics, reduces performance through power absorption in biological tissues, and changes the antenna impedance. The study specifically examines a rectangular loop antenna placed near a simplified three-layer model of the human torso. Results show the antenna's reflection coefficient and radiation pattern are affected by the distance between the antenna and body, as well as variations in the thickness of the lowest muscle layer to account for cardiac activity.
1) The document describes a wavelet-based technique for denoising underwater signals affected by wind-driven ambient noise. It uses discrete wavelet transform to decompose the noisy signal into coefficients. 2) A threshold is calculated using the universal threshold method and applied to the coefficients to remove noise. Hard and soft thresholding are evaluated. 3) The denoised signal is then reconstructed from the modified coefficients using inverse discrete wavelet transform. The technique is shown to effectively reduce wind noise and improve the signal-to-noise ratio.
Accurate characterizations of material using microwave T-resonator for solid ...TELKOMNIKA JOURNAL
The topic of microwave sensors in enclosures is one of the most active areas in material characterization research today due to its wide applications in various industries. Surprisingly, a microwave sensor technology has been comprehensively investigated and there is an industry demand for an
accurate instrument of material characterization such as food industry, quality control, chemical composition analysis and bio-sensing. These accurate instruments have the ability to understand the properties of materials composition based on chemical, physical, magnetic, and electric characteristics. Therefore, a design of the T-resonator has been introduced
and investigated for an accurate measurement of material properties characterizations. This sensor is designed and fabricated on a 0.787 mm-thickness Roger 5880 substrate for the first resonant frequency to resonate at 2.4 GHz under unloaded conditions. Various standard dielectric of the sample under test (SUT) are tested to validate the sensitivity which making it a promising low-cost, compact in size, ease of fabrication and small SUT preparation for applications requiring novel sensing techniques inquality and control industries.
Analysis and simulations of optimal geometry shapes of the 4 and 9 nano hole ...IJECEIAES
The possibility to limit and manipulate photons at nanometer scales attracted a lot of interest for exciting applications from subwavelength in laser, biosensors, biomedical and optoelectronics devices, the sensor optical properties, however; are complex due to two resonances through propagating and localized surface plasmons. The optical properties of surface plasmons (SPs) at the resonant wavelength is depending on the geometrical nanostructure of materials. In this article, we used different geometry of nanoholes array, 4 and 9 nanoholes array in a metallic film gold nanoparticle with different thickness (20,50,100) nm on SiO2 substrate with refractive index 1.46, we designed two different geometries; 4- holes: hole radius r1=200 nm, period p1=600 nm; and 9- holes: r2=100 nm, period p2=300 nm. Transmission and reflection spectrum have been calculated and simulated by FDTD Lumerical program. From results are observed the effect of thickness is interesting, transmission is increased at (t=20nm) for two arrays. Furthermore, the number of hole and its area has an influence on optical transmission and other parameters (E, H, Ref) which are characteristics of design of metallic nanostructure. We can see that there is a peak value of the wavelength at 519 nm approximately to 73% strong light transmission with 4-NHA in the other hand wavelength of 519 nm transmission is 45% with 9-NHA. strong light transmission is hopeful for many applications (biomedical devices, nanoantennas and laser optical fiber).
Determination of solid material permittivity using T-ring resonator for food ...TELKOMNIKA JOURNAL
In this paper, we present a simple design of a T-ring resonator sensor for characterizing solid detection. The sensor is based on a planar microwave ring resonator and operating at 4.2 GHz frequency with a high-quality factor and sensitivity. An optimization of the T-ring geometry and materials were made to achieve high sensitivity for microwave material characterizations. This technique can determine the properties of solid materials from range of 2 GHz to 12 GHz frequencies. Techniques of current microwave resonator are usually measuring the properties of material at frequencies with a wide range; however, their accuracy is limited. Contrary to techniques that have a narrowband which is normally measuring the properties of materials to a high-accuracy with limitation to only a single frequency. This sensor has a capability of measuring the properties of materials at frequencies of wide range to a high-accuracy. A good agreement is achieved between the simulated results of the tested materials and the values of the manufacturer’s Data sheets. An empirical equation has been developed accordingly for the simulated results of the tested materials. Various standard materials have been tested for validation and verification of the sensor sensitivity. The proposed concept enables the detection and characterization of materials and it has miniaturized the size with low cost, reusable, reliable, and ease of design fabrication with using a small size of tested sample. It is inspiring a broader of interest in developing microwave planar sensors and improving their applications in food industry, quality control and biomedical materials.
This document summarizes research on improving ambiguity resolution in GPS positioning using an ionospheric differential correction model. Data was collected from two stations in Malaysia's equatorial region over a short baseline of 33 km. Applying corrections from an ionospheric model led to ambiguities being resolved faster, in under an hour, compared to uncorrected data which took over 2.5 hours. The model also produced smaller standard errors in baseline positioning and increased the variance ratio and decreased reference variance indicators of successful ambiguity resolution. The findings show that an ionospheric differential correction model can improve ambiguity resolution for single frequency GPS over short baselines.
Tunable and storage potential wells using microring resonator system for bio ...University of Malaya (UM)
The document summarizes a student paper that proposes using a microring resonator system to generate tunable and storage potential wells for trapping and delivering bio-cells or molecules. The system utilizes the concepts of dark solitons and potential wells to introduce trapping forces. It consists of two microring resonators that allow a soliton pulse input to one to propagate and form a resonant output that becomes the input to the second microring resonator. The throughput field can then be controlled and stored by using the resonators, with amplified signals occurring between the left and right nanoring resonators. The technique could potentially be used for applications like transporting plant nutrients for feeding in a similar manner to drug delivery.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
This document presents a new method for detecting corrosion in pipelines based on measuring natural frequencies. The method uses Rayleigh's Law to relate changes in natural frequency to the location and degree of corrosion damage. Finite element models are used to validate the method. The models show that measuring the first and second natural frequencies can accurately determine both where corrosion is located and how severe it is, as indicated by the reduction in bending stiffness. The accuracy depends on having a reasonable estimate of the length of the corroded region. This new natural frequency method provides a simple way to detect pipeline corrosion compared to existing techniques.
Radiation Impedance Of Capacitive Micromachined Ultrasonic TransducersMuhammed N. Senlik
This dissertation analyzes the radiation impedance of capacitive micromachined ultrasonic transducers (cMUTs). It calculates the radiation impedance of a single circular cMUT membrane analytically and using finite element simulations up to the parallel resonance frequency. It then extends this to calculate the radiation impedance of an array of circular cMUT cells arranged in a hexagonal pattern. The radiation impedance is shown to strongly depend on the cell spacing. Higher radiation resistance improves the bandwidth and efficiency of cMUTs. Arranging cells optimizes the radiation resistance for airborne applications.
03 motl lukic_yakovlevelsherbenietal_printedantennadesignspatialpowercombinerCarlos Andres
The document discusses printed antenna designs for broadband waveguide-based spatial power combiners. It investigates the effect of antenna design parameters on bandwidth performance. Meander-slot antennas and their variations are proposed to increase bandwidth and efficiency compared to traditional rectangular patch and slot antennas. Numerical results show interacting single patch and meander slot antennas, as well as arrays of interacting U-strip, U-slot, and meander slot antennas, have advantages in scattering characteristics for spatial power combining applications.
This document summarizes a study that aimed to replicate the results of a previous paper on selectively stimulating neuronal fibers or cell bodies using different asymmetric biphasic current waveforms. The study developed a multi-compartment Hodgkin-Huxley neuronal model in MATLAB and simulated the response of populations of neurons to different stimulus waveforms. The results showed that an anodic-leading asymmetric biphasic waveform selectively activated fibers, while a cathodic-leading waveform preferentially activated cell bodies, consistent with the previous study.
Novel experimental observations in percolative systemsRAVI BHATIA
The presentation in based on interesting experimental results of percolative systems. A weak temperature dependence of conductivity is observed in composite of 0.4 wt %. The coercivity of Fe-MWNT/PS composites varies non-monotonically as a function of MWNT loading.
Transmission spectra of single ring coupled-waveguide resonator configuration...TELKOMNIKA JOURNAL
Development of optical waveguide resonators have greatly expanded and continues to grow since they have kinds potential applications such as wavelength filtering, switching, coupling and multiplexing. One of resonators, coupled waveguides, ring resonators are designed and operated using various coupling configurations. Ring resonators can be particularly used as wavelength filter if the wavelength can fit a whole multiple time in the circumference of the ring. This article proposes to investigate the transmission spectra from the power source and amplify it in linearized ring resonator configurations and varies the input amplitude on five different wavelengths. With finite difference time domain method, the geometry and power source are simulated to obtain the better result and configuration. The results show the intensity phenomena of filtering in optical circuit.
Implementation and analysis of multiple criteria decision routing algorithm f...prjpublications
This document summarizes a research paper that proposes and evaluates a new routing algorithm called Multiple Criteria Decision Routing (MCDR) for wireless sensor networks. MCDR selects the next node to forward data based on both the node's distance to the sink and its remaining energy. The performance of MCDR is compared to flooding algorithm through simulation. Simulation results show that MCDR has better performance than flooding in terms of energy efficiency and fast data delivery.
Mems based optical sensor for salinity measurementprjpublications
1. The document describes a MEMS-based optical sensor using a two-dimensional photonic crystal slab waveguide for measuring salinity.
2. The sensor takes advantage of the fact that the refractive index of sea water changes with salinity concentration. It detects these small refractive index changes by measuring the resulting effective index change in the photonic crystal slab waveguide.
3. Simulation results show that even small refractive index changes due to salinity produce a more significant change in effective index, demonstrating the high sensitivity of the designed sensor. Effective index decreases exponentially with increasing salinity percentage measured.
SUITABLE MOTHER WAVELET SELECTION FOR EEG SIGNALS ANALYSIS: FREQUENCY BANDS D...sipij
Wavelet transform (WT) is a powerful modern tool for time-frequency analysis of non-stationary signals such as electroencephalogram (EEG). The aim of this study is to choose the best and suitable mother wavelet function (MWT) for analyzing normal, seizure-free and seizured EEG signals. Several MWTs can be used, but the best MWT is the one that conserves the quasi-totality of information of the original signal on wavelet coefficients and gather more EEG rhythms in terms of frequency. In this study, Daubechies, Symlets and Coiflets orthogonal families were used as bsis mother wavelet functions. The percentage rootmeans square difference (PRD), the signal to noise ratio (SNR) and the simulated frequencies as the selection metrics. Simulation results indicate Daubechies wavelet at level 4 (Db4) as the most suitable MWT for EEG frequency bands decomposition.Furthermore, due to the redundancy of the extracted features, linear discriminant analysis (LDA) is applied for feature selection. Scatter plot showed that the selected feature vector represents the amount of changes in frequency distribution and carries most of the discriminative and representative information about their classes. Then, this study can provide a reference for the selection of a suitable MWT and discriminativefeatures.
A design and simulation of optical pressure sensor based on photonic crystal ...prjpublications
This document describes the design and simulation of an optical pressure sensor based on photonic crystals in the sub-micron range. Two designs of the pressure sensor are proposed and modeled. The first uses a two-dimensional square lattice photonic crystal with rods in air and a waveguide carved between two dielectric slabs. The second uses a two-dimensional hexagonal lattice photonic crystal with holes in a dielectric slab and a waveguide. Applied pressure moves the upper slab, changing the waveguide dimension and altering the transmission spectrum in a way that corresponds to the pressure level. The designs were simulated using the Finite Difference Time Domain method with the MEEP software tool.
Effect of Material Thickness on Attenuation (dB) of PTFE Using Finite Element...Abubakar Yakubu
This research article examines how the thickness of polytetrafluoroethylene (PTFE) samples affects the attenuation of electromagnetic waves at X-band frequency using finite element method (FEM) simulations. The results show that as the thickness of the PTFE samples increases, the attenuation also increases. Specifically, the 15 mm thick PTFE sample has an attenuation of -3.32 dB, the 30 mm sample has an attenuation of 0.64 dB, and the 50 mm sample has an attenuation of 1.97 dB. The study finds that increasing sample thickness leads to a decrease in electromagnetic wave transmission and an increase in attenuation.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Behavior of Ultrasound Energy in the Presence of ObstacleIRJET Journal
This document discusses using ultrasound energy to detect obstacles embedded within concrete cubes. Ultrasound signals at 50kHz were passed through concrete cubes of varying grade (M20, M30, M40) and size (220mm, 320mm) with and without obstacles like plywood, thermocol, and rods. The ultrasound signal was captured and the energy was calculated using MATLAB. Tables show the area under the energy curve is lower when an obstacle is present, indicating energy absorption. Reinforcement did not significantly affect energy. This method can detect foreign objects in concrete and assess structural health.
Damage detection in cfrp plates by means of numerical modeling of lamb waves ...eSAT Journals
Abstract
The paper presents an application of modeling acoustic waves propagation in a carbon fiber reinforced plastic (CFRP) plates for
damage detection. This task is a part of non-destructive testing (NDT) methods which are very important in many industry
branches. Propagation of Lamb waves is modeled using three-dimensional finite element method by means of commercial
software. In the paper three different cases of plate structures with and without flaws are considered to present review of selected
methods for the detection of defects in time and frequency domain. These are comparisons of: A-scans, B-scans, dispersion
curves, spectrograms, scalograms and energy plots. Developed numerical model first has been validated by means of analytical
solution for isotropic plate.
Keywords: Lamb waves, non-destructive testing, finite element method, damage detection
The document summarizes a study on the effects of human tissue on the performance of a loop antenna. It discusses how the human body, being a lossy dielectric medium, interacts with the near field of antennas. This interaction causes changes to the antenna characteristics, reduces performance through power absorption in biological tissues, and changes the antenna impedance. The study specifically examines a rectangular loop antenna placed near a simplified three-layer model of the human torso. Results show the antenna's reflection coefficient and radiation pattern are affected by the distance between the antenna and body, as well as variations in the thickness of the lowest muscle layer to account for cardiac activity.
1) The document describes a wavelet-based technique for denoising underwater signals affected by wind-driven ambient noise. It uses discrete wavelet transform to decompose the noisy signal into coefficients. 2) A threshold is calculated using the universal threshold method and applied to the coefficients to remove noise. Hard and soft thresholding are evaluated. 3) The denoised signal is then reconstructed from the modified coefficients using inverse discrete wavelet transform. The technique is shown to effectively reduce wind noise and improve the signal-to-noise ratio.
1) The document describes a wavelet-based technique for denoising underwater signals affected by wind-driven ambient noise. It uses discrete wavelet transform to decompose the noisy signal into coefficients. 2) Thresholding is then applied to the coefficients, where threshold values are calculated separately for each level of decomposition using universal thresholding. 3) The signal is then reconstructed from the modified coefficients after thresholding to reduce noise. The technique aims to improve the signal-to-noise ratio of underwater signals corrupted by wind noise.
Digital signal processing techniques for lti fiber impairment compensationeSAT Journals
Abstract Coherent detection is one of the active research areas for the development of high speed, high spectral efficient optical communication network. Digital signal processing is the important technique for compensating the fiber transmission impairments because of number of advantages such as signal can be amplified, delayed, splitted and manipulated without degrading the signal quality. This paper presents DSP compensation algorithms for linear time invariant (LTI) impairment such as chromatic dispersion (CD) and polarization mode dispersion (PMD) in optical fiber communication. We presented a mathematical framework for compensation of LTI fiber impairments. This paper also focuses the different compensation methods both in time and frequency domain for chromatic dispersion compensation. These DSP techniques confirm that coherent detection with high data rates will become feasible in future for compensating transmission impairments. Keywords: Coherent Detection, Chromatic Dispersion, Polarization Mode Dispersion
Evolutionary algorithms for optimum design of thin broadband multilayer micro...eSAT Journals
Abstract In this paper we focused on the comparative study of three very popular and most recently developed nature inspired evolutionary algorithms namely Biogeography based optimization algorithm (BBO), Flower pollination algorithm (FPA) and Artificial bee colony optimization algorithm (ABC) for developing a model of 6 layers thin broadband (0.2-20GHz) microwave absorber. The model is optimized for oblique wide angle of incidence (450, 600) taking both TE and TM polarization of the electromagnetic wave under consideration. The primary goal of our design is to minimizing the overall reflection coefficient of the absorber and its total thickness by selecting the proper layer of materials from a predefined database of existing materials. 8 different models are presented and synthesize considering both these design consideration simultaneously and for only overall reflection coefficient of the absorber while total thickness is not taken into consideration during optimization for each cases. The optimum values of all the significant parameters of the multilayer absorber for different models have been compared and tabulated using BBO, FPA and ABC algorithms which established the superiority of our proposed design. Keywords: Multilayer microwave absorber, Oblique incidence, Broadband, Evolutionary algorithms, Arbitrary polarization
Due to high demand of using cordless mobile device, the interest in wireless energy transfer (WET) has been growth intensively. This paper presented a method to obtained optimum transmitter receiver ratio for maximum performance of WET system using different initial antenna size at various distance. An optimized algorithm has been developed to determine the optimum ratios that yield the highest wireless transfer efficiency (WTE) at near field communication (NFC) frequency, 13.56MHz. 30mm x 30mm single square loop antenna is used as initial size of both transmitter and receiver using FR4 with operating distance = 50mm. Operating distance and initial size of the antenna will be varied and the effect to the WTE will be studied using Matlab, verified using Microsoft Studio CST. At distance = 50mm and initial size of the antenna = 30mm x 30mm, optimum transmitter to receiver ratio equal to 1:3 is obtained. The pattern of optimum transmitter receiver ratio between Matlab and CST has met an agreement. This research limited to integer transmitter receiver ratio used only and no decimal number being involved in magnify the transmitter size.
Available online at [www.ijeete.com]EFFECT OF DISPERSION AND FIBER LENGTH ON ...Ankur Bindal
This paper introduces the non linear optical effect known as four wave mixing (FWM). In wavelength division multiplexing (WDM) systems four wave mixing can strongly affect the transmission performance on an optical link. As a result it is important to investigate the impact of FWM on the design and performance of WDM optical communication systems. The main objective of this paper is to analyze the FWM power for different values of fiber length and dispersion by designing and simulating a model in Optisim. In this paper, we have simulated the FWM design for three waves. The results obtained show that when the optical fiber length and dispersion value is increased FWM effect reduces. This result confirms that the fiber nonlinearities play decisive role in the WDM.
Time-Frequency Representation For Estimating Young’s Modulus And Poisson’s Ra...IJERA Editor
The present paper examines a new procedure for estimating Young‘s modulus and Poisson‘s ratio of homogeneous materials constituting the one-layer thin tubes. The work is done from the use of the timefrequency representation. Spectrogram and its reassigned version have been chosen to analyze experimentally acoustic signals backscattered by air-filled tubes immersed in water. For reduced frequencies ranging from 0.1 to 500, time-frequency images have shown the presence of the Symmetrical and the Antisymmetrical waves. Satisfactory resolution and good localization in the time-frequency plane have been observed in the case of concentrated spectrogram. Reduced cutoff frequencies of A1 and S1 waves have also been extracted from Spectrogram and concentrated Spectrogram time-frequency images. A good agreement has, therefore, been observed. Comparisons with results obtained by experiment indicate that mechanical parameters such as Young‘s modulus and Poisson‘s ratio of aluminum and copper are evaluated accurately
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Scattering Regimes for Underwater Optical Wireless Communications using Monte...IJECEIAES
Optical wireless communications has shown tremendous potential for underwater applications as it can provide higher bandwidth and better security compared to acoustic technologies. In this paper, an investigation on scattering regimes for underwater links using Monte Carlo simulation has been presented.While the focus of this paper is on diffuse links, the simulation results of collimated links is also provided for comparison purpose. Three types of water namely clear, coastal and turbid water are being used in the simulation. It is shown that the effect of scattering on the path loss cannot be accurately modeled by the existing channel model; ie. Beers-Lambert (BL) law. It has been shown that the distance at which the unscattered light drops to zero can be used to estimate the transition point for the scattering regimes in case of diffuse links. The transition point for diffuse links in coastal water and turbid water can be estimated to be around 22 m and 4 m respectively. Further analysis on the scattering order probability at different scattering regimes illustrates how scattering is affected by beam size, water turbidity and distance. From the frequency response plot, it is estimated that the bandwidth of several order of GHz can be achieved when the links are operating in the minimal scattering region and will reduce to several hundreds of MHz when the link is operating in multiple scattering region.
Analysis of Phase Error and Cross Talk for the Young Interferometer Immunosensoriosrjce
This document analyzes factors that influence measurement errors in a four-channel Young interferometer immunosensor. Through simulations in Matlab, it is shown that increasing the CCD camera resolution to 2048 pixels and applying a Hanning window to the interference pattern can significantly reduce phase error and cross-talk. Noise averaging through overlapping 16 or more signals also leads to a notable reduction in errors by a factor of around 7.58. The document explores these techniques to minimize errors in the immunosensor measurements.
Analysis of propagation of modulated optical signal in an integrated optic enviIAEME Publication
This document analyzes the propagation of modulated optical signals in integrated optic environments. It begins by discussing how modulation distributes an optical signal's power across multiple frequency components, requiring analysis beyond the monochromatic assumption. It then models a slab waveguide numerically to show how propagation constants and mode profiles vary with frequency. Finally, it simulates the phase variations experienced by different frequency components of a modulated signal propagating through integrated optic structures like straight waveguides and bends, demonstrating their ability to support wide bandwidths.
Airflow vibration of diaphragmatic breathing: model and demonstration using o...TELKOMNIKA JOURNAL
This document discusses a study that modeled and experimentally demonstrated human diaphragmatic breathing using an optical fiber sensor. The study first modeled lung airflow using finite element analysis and the Navier-Stokes equations. It then designed an elastic belt with sinusoidally bent single mode fiber and fiber Bragg grating to detect breathing movements. Simulation results showed airflow velocity increased up to 4 m/s in smaller lung branches. Experiments found the largest power loss with a 0.8 cm buffer diameter. Fiber bending detected power losses from -0.18 to -0.28 dBm during breathing. However, fiber Bragg grating showed higher sensitivity. The study concluded the sensor successfully modeled and tested respiratory airflow, with simulations showing velocity increases with
1. The document describes a microstrip diplexer design inspired by electromagnetically induced transparency (EIT). EIT allows wave propagation within a medium's absorption spectrum through quantum interference between atomic transition pathways.
2. The proposed diplexer exploits an analogous EIT-like interference mechanism using pairs of unequal open-circuit stubs on a microstrip transmission line. This creates separate transparent passbands for diplexing action at different frequencies.
3. A prototype was fabricated at C-band frequencies with passbands centered at 4.6 GHz and 5.5 GHz, achieving insertion losses of 0.59 dB and 0.61 dB respectively. High isolation of 40 dB was observed between the passbands due
A Review Of The Skin Effect As Applied To Thin Film InterconnectionsSabrina Ball
This document provides a review of theoretical approaches that have been used to study the skin effect phenomenon in thin film interconnections. It discusses how the skin effect causes current to concentrate near the surface of a conductor at high frequencies. It surveys several common theoretical methods for modeling the skin effect, including incremental inductance, perturbational, and full wave analysis methods. These methods allow calculating the frequency-dependent resistance and current distribution in conductors. However, most are only valid when the skin effect is fully developed at high frequencies and assume transmission line modes that break down at very high frequencies relevant to digital signal propagation. Improved modeling approaches are needed that can accurately model skin effect behavior over broad digital signal frequency ranges.
Decimal convertor application for optical wireless communication by generatin...University of Malaya (UM)
This document proposes a system to generate dark and bright optical soliton pulses for use in secure wireless communication networks. It uses microring resonators to generate multiple wavelengths of optical pulses. These pulses are then sent through a polarization control system to encode them as quantum codes using dark and bright solitons. The soliton pulses can then be converted to digital logic codes using a decimal converter and transmitted securely over wireless networks. The system is able to generate multi-wavelength soliton pulses ranging from 1.55 to 1.56 micrometers with a full width at half maximum of 10 picometers and a free spectral range of 600 picometers.
Similar to Incident and reflected two waves correlation with cancellous bone structure (20)
Amazon products reviews classification based on machine learning, deep learni...TELKOMNIKA JOURNAL
In recent times, the trend of online shopping through e-commerce stores and websites has grown to a huge extent. Whenever a product is purchased on an e-commerce platform, people leave their reviews about the product. These reviews are very helpful for the store owners and the product’s manufacturers for the betterment of their work process as well as product quality. An automated system is proposed in this work that operates on two datasets D1 and D2 obtained from Amazon. After certain preprocessing steps, N-gram and word embedding-based features are extracted using term frequency-inverse document frequency (TF-IDF), bag of words (BoW) and global vectors (GloVe), and Word2vec, respectively. Four machine learning (ML) models support vector machines (SVM), logistic regression (RF), logistic regression (LR), multinomial Naïve Bayes (MNB), two deep learning (DL) models convolutional neural network (CNN), long-short term memory (LSTM), and standalone bidirectional encoder representations (BERT) are used to classify reviews as either positive or negative. The results obtained by the standard ML, DL models and BERT are evaluated using certain performance evaluation measures. BERT turns out to be the best-performing model in the case of D1 with an accuracy of 90% on features derived by word embedding models while the CNN provides the best accuracy of 97% upon word embedding features in the case of D2. The proposed model shows better overall performance on D2 as compared to D1.
Design, simulation, and analysis of microstrip patch antenna for wireless app...TELKOMNIKA JOURNAL
In this study, a microstrip patch antenna that works at 3.6 GHz was built and tested to see how well it works. In this work, Rogers RT/Duroid 5880 has been used as the substrate material, with a dielectric permittivity of 2.2 and a thickness of 0.3451 mm; it serves as the base for the examined antenna. The computer simulation technology (CST) studio suite is utilized to show the recommended antenna design. The goal of this study was to get a more extensive transmission capacity, a lower voltage standing wave ratio (VSWR), and a lower return loss, but the main goal was to get a higher gain, directivity, and efficiency. After simulation, the return loss, gain, directivity, bandwidth, and efficiency of the supplied antenna are found to be -17.626 dB, 9.671 dBi, 9.924 dBi, 0.2 GHz, and 97.45%, respectively. Besides, the recreation uncovered that the transfer speed side-lobe level at phi was much better than those of the earlier works, at -28.8 dB, respectively. Thus, it makes a solid contender for remote innovation and more robust communication.
Design and simulation an optimal enhanced PI controller for congestion avoida...TELKOMNIKA JOURNAL
This document describes using a snake optimization algorithm to tune the gains of an enhanced proportional-integral controller for congestion avoidance in a TCP/AQM system. The controller aims to maintain a stable and desired queue size without noise or transmission problems. A linearized model of the TCP/AQM system is presented. An enhanced PI controller combining nonlinear gain and original PI gains is proposed. The snake optimization algorithm is then used to tune the parameters of the enhanced PI controller to achieve optimal system performance and response. Simulation results are discussed showing the proposed controller provides a stable and robust behavior for congestion control.
Improving the detection of intrusion in vehicular ad-hoc networks with modifi...TELKOMNIKA JOURNAL
Vehicular ad-hoc networks (VANETs) are wireless-equipped vehicles that form networks along the road. The security of this network has been a major challenge. The identity-based cryptosystem (IBC) previously used to secure the networks suffers from membership authentication security features. This paper focuses on improving the detection of intruders in VANETs with a modified identity-based cryptosystem (MIBC). The MIBC is developed using a non-singular elliptic curve with Lagrange interpolation. The public key of vehicles and roadside units on the network are derived from number plates and location identification numbers, respectively. Pseudo-identities are used to mask the real identity of users to preserve their privacy. The membership authentication mechanism ensures that only valid and authenticated members of the network are allowed to join the network. The performance of the MIBC is evaluated using intrusion detection ratio (IDR) and computation time (CT) and then validated with the existing IBC. The result obtained shows that the MIBC recorded an IDR of 99.3% against 94.3% obtained for the existing identity-based cryptosystem (EIBC) for 140 unregistered vehicles attempting to intrude on the network. The MIBC shows lower CT values of 1.17 ms against 1.70 ms for EIBC. The MIBC can be used to improve the security of VANETs.
Conceptual model of internet banking adoption with perceived risk and trust f...TELKOMNIKA JOURNAL
Understanding the primary factors of internet banking (IB) acceptance is critical for both banks and users; nevertheless, our knowledge of the role of users’ perceived risk and trust in IB adoption is limited. As a result, we develop a conceptual model by incorporating perceived risk and trust into the technology acceptance model (TAM) theory toward the IB. The proper research emphasized that the most essential component in explaining IB adoption behavior is behavioral intention to use IB adoption. TAM is helpful for figuring out how elements that affect IB adoption are connected to one another. According to previous literature on IB and the use of such technology in Iraq, one has to choose a theoretical foundation that may justify the acceptance of IB from the customer’s perspective. The conceptual model was therefore constructed using the TAM as a foundation. Furthermore, perceived risk and trust were added to the TAM dimensions as external factors. The key objective of this work was to extend the TAM to construct a conceptual model for IB adoption and to get sufficient theoretical support from the existing literature for the essential elements and their relationships in order to unearth new insights about factors responsible for IB adoption.
Efficient combined fuzzy logic and LMS algorithm for smart antennaTELKOMNIKA JOURNAL
The smart antennas are broadly used in wireless communication. The least mean square (LMS) algorithm is a procedure that is concerned in controlling the smart antenna pattern to accommodate specified requirements such as steering the beam toward the desired signal, in addition to placing the deep nulls in the direction of unwanted signals. The conventional LMS (C-LMS) has some drawbacks like slow convergence speed besides high steady state fluctuation error. To overcome these shortcomings, the present paper adopts an adaptive fuzzy control step size least mean square (FC-LMS) algorithm to adjust its step size. Computer simulation outcomes illustrate that the given model has fast convergence rate as well as low mean square error steady state.
Design and implementation of a LoRa-based system for warning of forest fireTELKOMNIKA JOURNAL
This paper presents the design and implementation of a forest fire monitoring and warning system based on long range (LoRa) technology, a novel ultra-low power consumption and long-range wireless communication technology for remote sensing applications. The proposed system includes a wireless sensor network that records environmental parameters such as temperature, humidity, wind speed, and carbon dioxide (CO2) concentration in the air, as well as taking infrared photos.The data collected at each sensor node will be transmitted to the gateway via LoRa wireless transmission. Data will be collected, processed, and uploaded to a cloud database at the gateway. An Android smartphone application that allows anyone to easily view the recorded data has been developed. When a fire is detected, the system will sound a siren and send a warning message to the responsible personnel, instructing them to take appropriate action. Experiments in Tram Chim Park, Vietnam, have been conducted to verify and evaluate the operation of the system.
Wavelet-based sensing technique in cognitive radio networkTELKOMNIKA JOURNAL
Cognitive radio is a smart radio that can change its transmitter parameter based on interaction with the environment in which it operates. The demand for frequency spectrum is growing due to a big data issue as many Internet of Things (IoT) devices are in the network. Based on previous research, most frequency spectrum was used, but some spectrums were not used, called spectrum hole. Energy detection is one of the spectrum sensing methods that has been frequently used since it is easy to use and does not require license users to have any prior signal understanding. But this technique is incapable of detecting at low signal-to-noise ratio (SNR) levels. Therefore, the wavelet-based sensing is proposed to overcome this issue and detect spectrum holes. The main objective of this work is to evaluate the performance of wavelet-based sensing and compare it with the energy detection technique. The findings show that the percentage of detection in wavelet-based sensing is 83% higher than energy detection performance. This result indicates that the wavelet-based sensing has higher precision in detection and the interference towards primary user can be decreased.
A novel compact dual-band bandstop filter with enhanced rejection bandsTELKOMNIKA JOURNAL
In this paper, we present the design of a new wide dual-band bandstop filter (DBBSF) using nonuniform transmission lines. The method used to design this filter is to replace conventional uniform transmission lines with nonuniform lines governed by a truncated Fourier series. Based on how impedances are profiled in the proposed DBBSF structure, the fractional bandwidths of the two 10 dB-down rejection bands are widened to 39.72% and 52.63%, respectively, and the physical size has been reduced compared to that of the filter with the uniform transmission lines. The results of the electromagnetic (EM) simulation support the obtained analytical response and show an improved frequency behavior.
Deep learning approach to DDoS attack with imbalanced data at the application...TELKOMNIKA JOURNAL
A distributed denial of service (DDoS) attack is where one or more computers attack or target a server computer, by flooding internet traffic to the server. As a result, the server cannot be accessed by legitimate users. A result of this attack causes enormous losses for a company because it can reduce the level of user trust, and reduce the company’s reputation to lose customers due to downtime. One of the services at the application layer that can be accessed by users is a web-based lightweight directory access protocol (LDAP) service that can provide safe and easy services to access directory applications. We used a deep learning approach to detect DDoS attacks on the CICDDoS 2019 dataset on a complex computer network at the application layer to get fast and accurate results for dealing with unbalanced data. Based on the results obtained, it is observed that DDoS attack detection using a deep learning approach on imbalanced data performs better when implemented using synthetic minority oversampling technique (SMOTE) method for binary classes. On the other hand, the proposed deep learning approach performs better for detecting DDoS attacks in multiclass when implemented using the adaptive synthetic (ADASYN) method.
The appearance of uncertainties and disturbances often effects the characteristics of either linear or nonlinear systems. Plus, the stabilization process may be deteriorated thus incurring a catastrophic effect to the system performance. As such, this manuscript addresses the concept of matching condition for the systems that are suffering from miss-match uncertainties and exogeneous disturbances. The perturbation towards the system at hand is assumed to be known and unbounded. To reach this outcome, uncertainties and their classifications are reviewed thoroughly. The structural matching condition is proposed and tabulated in the proposition 1. Two types of mathematical expressions are presented to distinguish the system with matched uncertainty and the system with miss-matched uncertainty. Lastly, two-dimensional numerical expressions are provided to practice the proposed proposition. The outcome shows that matching condition has the ability to change the system to a design-friendly model for asymptotic stabilization.
Implementation of FinFET technology based low power 4×4 Wallace tree multipli...TELKOMNIKA JOURNAL
Many systems, including digital signal processors, finite impulse response (FIR) filters, application-specific integrated circuits, and microprocessors, use multipliers. The demand for low power multipliers is gradually rising day by day in the current technological trend. In this study, we describe a 4×4 Wallace multiplier based on a carry select adder (CSA) that uses less power and has a better power delay product than existing multipliers. HSPICE tool at 16 nm technology is used to simulate the results. In comparison to the traditional CSA-based multiplier, which has a power consumption of 1.7 µW and power delay product (PDP) of 57.3 fJ, the results demonstrate that the Wallace multiplier design employing CSA with first zero finding logic (FZF) logic has the lowest power consumption of 1.4 µW and PDP of 27.5 fJ.
Evaluation of the weighted-overlap add model with massive MIMO in a 5G systemTELKOMNIKA JOURNAL
The flaw in 5G orthogonal frequency division multiplexing (OFDM) becomes apparent in high-speed situations. Because the doppler effect causes frequency shifts, the orthogonality of OFDM subcarriers is broken, lowering both their bit error rate (BER) and throughput output. As part of this research, we use a novel design that combines massive multiple input multiple output (MIMO) and weighted overlap and add (WOLA) to improve the performance of 5G systems. To determine which design is superior, throughput and BER are calculated for both the proposed design and OFDM. The results of the improved system show a massive improvement in performance ver the conventional system and significant improvements with massive MIMO, including the best throughput and BER. When compared to conventional systems, the improved system has a throughput that is around 22% higher and the best performance in terms of BER, but it still has around 25% less error than OFDM.
Reflector antenna design in different frequencies using frequency selective s...TELKOMNIKA JOURNAL
In this study, it is aimed to obtain two different asymmetric radiation patterns obtained from antennas in the shape of the cross-section of a parabolic reflector (fan blade type antennas) and antennas with cosecant-square radiation characteristics at two different frequencies from a single antenna. For this purpose, firstly, a fan blade type antenna design will be made, and then the reflective surface of this antenna will be completed to the shape of the reflective surface of the antenna with the cosecant-square radiation characteristic with the frequency selective surface designed to provide the characteristics suitable for the purpose. The frequency selective surface designed and it provides the perfect transmission as possible at 4 GHz operating frequency, while it will act as a band-quenching filter for electromagnetic waves at 5 GHz operating frequency and will be a reflective surface. Thanks to this frequency selective surface to be used as a reflective surface in the antenna, a fan blade type radiation characteristic at 4 GHz operating frequency will be obtained, while a cosecant-square radiation characteristic at 5 GHz operating frequency will be obtained.
Reagentless iron detection in water based on unclad fiber optical sensorTELKOMNIKA JOURNAL
A simple and low-cost fiber based optical sensor for iron detection is demonstrated in this paper. The sensor head consist of an unclad optical fiber with the unclad length of 1 cm and it has a straight structure. Results obtained shows a linear relationship between the output light intensity and iron concentration, illustrating the functionality of this iron optical sensor. Based on the experimental results, the sensitivity and linearity are achieved at 0.0328/ppm and 0.9824 respectively at the wavelength of 690 nm. With the same wavelength, other performance parameters are also studied. Resolution and limit of detection (LOD) are found to be 0.3049 ppm and 0.0755 ppm correspondingly. This iron sensor is advantageous in that it does not require any reagent for detection, enabling it to be simpler and cost-effective in the implementation of the iron sensing.
Impact of CuS counter electrode calcination temperature on quantum dot sensit...TELKOMNIKA JOURNAL
In place of the commercial Pt electrode used in quantum sensitized solar cells, the low-cost CuS cathode is created using electrophoresis. High resolution scanning electron microscopy and X-ray diffraction were used to analyze the structure and morphology of structural cubic samples with diameters ranging from 40 nm to 200 nm. The conversion efficiency of solar cells is significantly impacted by the calcination temperatures of cathodes at 100 °C, 120 °C, 150 °C, and 180 °C under vacuum. The fluorine doped tin oxide (FTO)/CuS cathode electrode reached a maximum efficiency of 3.89% when it was calcined at 120 °C. Compared to other temperature combinations, CuS nanoparticles crystallize at 120 °C, which lowers resistance while increasing electron lifetime.
In place of the commercial Pt electrode used in quantum sensitized solar cells, the low-cost CuS cathode is created using electrophoresis. High resolution scanning electron microscopy and X-ray diffraction were used to analyze the structure and morphology of structural cubic samples with diameters ranging from 40 nm to 200 nm. The conversion efficiency of solar cells is significantly impacted by the calcination temperatures of cathodes at 100 °C, 120 °C, 150 °C, and 180 °C under vacuum. The fluorine doped tin oxide (FTO)/CuS cathode electrode reached a maximum efficiency of 3.89% when it was calcined at 120 °C. Compared to other temperature combinations, CuS nanoparticles crystallize at 120 °C, which lowers resistance while increasing electron lifetime.
A progressive learning for structural tolerance online sequential extreme lea...TELKOMNIKA JOURNAL
This article discusses the progressive learning for structural tolerance online sequential extreme learning machine (PSTOS-ELM). PSTOS-ELM can save robust accuracy while updating the new data and the new class data on the online training situation. The robustness accuracy arises from using the householder block exact QR decomposition recursive least squares (HBQRD-RLS) of the PSTOS-ELM. This method is suitable for applications that have data streaming and often have new class data. Our experiment compares the PSTOS-ELM accuracy and accuracy robustness while data is updating with the batch-extreme learning machine (ELM) and structural tolerance online sequential extreme learning machine (STOS-ELM) that both must retrain the data in a new class data case. The experimental results show that PSTOS-ELM has accuracy and robustness comparable to ELM and STOS-ELM while also can update new class data immediately.
Electroencephalography-based brain-computer interface using neural networksTELKOMNIKA JOURNAL
This study aimed to develop a brain-computer interface that can control an electric wheelchair using electroencephalography (EEG) signals. First, we used the Mind Wave Mobile 2 device to capture raw EEG signals from the surface of the scalp. The signals were transformed into the frequency domain using fast Fourier transform (FFT) and filtered to monitor changes in attention and relaxation. Next, we performed time and frequency domain analyses to identify features for five eye gestures: opened, closed, blink per second, double blink, and lookup. The base state was the opened-eyes gesture, and we compared the features of the remaining four action gestures to the base state to identify potential gestures. We then built a multilayer neural network to classify these features into five signals that control the wheelchair’s movement. Finally, we designed an experimental wheelchair system to test the effectiveness of the proposed approach. The results demonstrate that the EEG classification was highly accurate and computationally efficient. Moreover, the average performance of the brain-controlled wheelchair system was over 75% across different individuals, which suggests the feasibility of this approach.
Adaptive segmentation algorithm based on level set model in medical imagingTELKOMNIKA JOURNAL
For image segmentation, level set models are frequently employed. It offer best solution to overcome the main limitations of deformable parametric models. However, the challenge when applying those models in medical images stills deal with removing blurs in image edges which directly affects the edge indicator function, leads to not adaptively segmenting images and causes a wrong analysis of pathologies wich prevents to conclude a correct diagnosis. To overcome such issues, an effective process is suggested by simultaneously modelling and solving systems’ two-dimensional partial differential equations (PDE). The first PDE equation allows restoration using Euler’s equation similar to an anisotropic smoothing based on a regularized Perona and Malik filter that eliminates noise while preserving edge information in accordance with detected contours in the second equation that segments the image based on the first equation solutions. This approach allows developing a new algorithm which overcome the studied model drawbacks. Results of the proposed method give clear segments that can be applied to any application. Experiments on many medical images in particular blurry images with high information losses, demonstrate that the developed approach produces superior segmentation results in terms of quantity and quality compared to other models already presented in previeous works.
Automatic channel selection using shuffled frog leaping algorithm for EEG bas...TELKOMNIKA JOURNAL
Drug addiction is a complex neurobiological disorder that necessitates comprehensive treatment of both the body and mind. It is categorized as a brain disorder due to its impact on the brain. Various methods such as electroencephalography (EEG), functional magnetic resonance imaging (FMRI), and magnetoencephalography (MEG) can capture brain activities and structures. EEG signals provide valuable insights into neurological disorders, including drug addiction. Accurate classification of drug addiction from EEG signals relies on appropriate features and channel selection. Choosing the right EEG channels is essential to reduce computational costs and mitigate the risk of overfitting associated with using all available channels. To address the challenge of optimal channel selection in addiction detection from EEG signals, this work employs the shuffled frog leaping algorithm (SFLA). SFLA facilitates the selection of appropriate channels, leading to improved accuracy. Wavelet features extracted from the selected input channel signals are then analyzed using various machine learning classifiers to detect addiction. Experimental results indicate that after selecting features from the appropriate channels, classification accuracy significantly increased across all classifiers. Particularly, the multi-layer perceptron (MLP) classifier combined with SFLA demonstrated a remarkable accuracy improvement of 15.78% while reducing time complexity.
Particle Swarm Optimization–Long Short-Term Memory based Channel Estimation w...IJCNCJournal
Paper Title
Particle Swarm Optimization–Long Short-Term Memory based Channel Estimation with Hybrid Beam Forming Power Transfer in WSN-IoT Applications
Authors
Reginald Jude Sixtus J and Tamilarasi Muthu, Puducherry Technological University, India
Abstract
Non-Orthogonal Multiple Access (NOMA) helps to overcome various difficulties in future technology wireless communications. NOMA, when utilized with millimeter wave multiple-input multiple-output (MIMO) systems, channel estimation becomes extremely difficult. For reaping the benefits of the NOMA and mm-Wave combination, effective channel estimation is required. In this paper, we propose an enhanced particle swarm optimization based long short-term memory estimator network (PSOLSTMEstNet), which is a neural network model that can be employed to forecast the bandwidth required in the mm-Wave MIMO network. The prime advantage of the LSTM is that it has the capability of dynamically adapting to the functioning pattern of fluctuating channel state. The LSTM stage with adaptive coding and modulation enhances the BER.PSO algorithm is employed to optimize input weights of LSTM network. The modified algorithm splits the power by channel condition of every single user. Participants will be first sorted into distinct groups depending upon respective channel conditions, using a hybrid beamforming approach. The network characteristics are fine-estimated using PSO-LSTMEstNet after a rough approximation of channels parameters derived from the received data.
Keywords
Signal to Noise Ratio (SNR), Bit Error Rate (BER), mm-Wave, MIMO, NOMA, deep learning, optimization.
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Prediction of Electrical Energy Efficiency Using Information on Consumer's Ac...PriyankaKilaniya
Energy efficiency has been important since the latter part of the last century. The main object of this survey is to determine the energy efficiency knowledge among consumers. Two separate districts in Bangladesh are selected to conduct the survey on households and showrooms about the energy and seller also. The survey uses the data to find some regression equations from which it is easy to predict energy efficiency knowledge. The data is analyzed and calculated based on five important criteria. The initial target was to find some factors that help predict a person's energy efficiency knowledge. From the survey, it is found that the energy efficiency awareness among the people of our country is very low. Relationships between household energy use behaviors are estimated using a unique dataset of about 40 households and 20 showrooms in Bangladesh's Chapainawabganj and Bagerhat districts. Knowledge of energy consumption and energy efficiency technology options is found to be associated with household use of energy conservation practices. Household characteristics also influence household energy use behavior. Younger household cohorts are more likely to adopt energy-efficient technologies and energy conservation practices and place primary importance on energy saving for environmental reasons. Education also influences attitudes toward energy conservation in Bangladesh. Low-education households indicate they primarily save electricity for the environment while high-education households indicate they are motivated by environmental concerns.
Sri Guru Hargobind Ji - Bandi Chor Guru.pdfBalvir Singh
Sri Guru Hargobind Ji (19 June 1595 - 3 March 1644) is revered as the Sixth Nanak.
• On 25 May 1606 Guru Arjan nominated his son Sri Hargobind Ji as his successor. Shortly
afterwards, Guru Arjan was arrested, tortured and killed by order of the Mogul Emperor
Jahangir.
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eleven years old when he became 6th Guru.
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authority (PIRI) and the other, his temporal authority (MIRI). He thus for the first time
initiated military tradition in the Sikh faith to resist religious persecution, protect
people’s freedom and independence to practice religion by choice. He transformed
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Blood finder application project report (1).pdfKamal Acharya
Blood Finder is an emergency time app where a user can search for the blood banks as
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searching the blood banks and blood donors it can be just done by installing the
application to the mobile.
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needed blood group during the time of the emergency.
This is an android application developed in Java and XML with the connectivity of
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This application allowed the user to get all the information regarding blood banks and
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Incident and reflected two waves correlation with cancellous bone structure
1. TELKOMNIKA Telecommunication, Computing, Electronics and Control
Vol. 18, No. 4, August 2020, pp. 1968~1975
ISSN: 1693-6930, accredited First Grade by Kemenristekdikti, Decree No: 21/E/KPT/2018
DOI: 10.12928/TELKOMNIKA.v18i4.14828 1968
Journal homepage: http://journal.uad.ac.id/index.php/TELKOMNIKA
Incident and reflected two waves correlation
with cancellous bone structure
Muhamad Amin Abd Wahab, Rubita Sudirman, Mohd Azhar Abdul Razak,
Fauzan Khairi Che Harun, Nurul Ashikin Abdul Kadir, Nasrul Humaimi Mahmood
School of Electrical Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Malaysia
Article Info ABSTRACT
Article history:
Received Aug 27, 2019
Revised Feb 25, 2020
Accepted Apr 7, 2020
The correlation in bone microstructure for ultrasound pulse echo technique
is still less accurate compared to through transmission technique. Previous
works demonstrated, reflected two modes wave has significant association
with bone porosity. The paper aims is to conduct simulation using pulse echo
technique to examine the relationship between fast and slow waves with
porosity of 2-dimensional cancellous bone models by comparing the result to
through transmission technique. The “incident” and “reflected” waves were
separated using bandlimited deconvolution method by estimating time
threshold of fast and slow waves' transfer function. The parameters
of the waves were computed, plotted versus porosity for six different
thicknesses and the correlation coefficients between them were compared.
The incident and reflected fast wave attenuations show marginally significant
correlation with porosity for both bone models orientations. Wave
propagation for parallel orientation dominated by incident and reflected fast
wave, meanwhile, perpendicular orientation dominated by incident slow
wave. The thickness factor affected wave amplitude but less affected
the attenuation. Because of propagation loss, reflected wave shows lower
correlation to porosity compared to incident wave. Hence, analyzing fast and
slow waves might improve the measurement accuracy of pulse echo
technique compared to using single mode wave to estimate bone quality.
Keywords:
Bandlimited deconvolution
Fast and slow wave
Pulse echo
Through transmission
Ultrasound
This is an open access article under the CC BY-SA license.
Corresponding Author:
Rubita Sudirman,
Department School of Electrical Engineering, Faculty of Engineering,
Universiti Teknologi Malaysia,
81310 UTM Johor Bahru, Malaysia.
Email: rubita@fke.utm.my
1. INTRODUCTION
Many applications in engineering, medicine [1], biology, and so on [2] using ultrasound technology in
their system for certain purposes. Previous study indicate that, the parameters of fast and slow waves was
associate more with the internal structure (microstructure) of the cancellous bone [3-9] and analysis these
waves could improve bone quality estimation via ultrasound. The anisotropy of cancellous bone can affect
time domain observation of fast and slow wave and most of the time, these waves overlapped with each
other [10]. Numerous techniques to decompose fast and slow wave were created by Wear and among them
was bandlimited deconvolution method. This method was simple to implement compare to other complex
methods such as Bayesian method [8, 11, 12]. This method also effectively decomposes fast and slow waves,
yet only implemented in through transmissions (TT) evaluation technique.
2. TELKOMNIKA Telecommun Comput El Control
Incident and reflected two waves correlation…. (Muhamad Amin Abd Wahab)
1969
Nonetheless, the TT technique was the only technique which widely used to investigate fast
and slow wave. However, it is difficult to perform bone health assessment at specific skeletal part such as hip
and backbone, due to the TT technique required a pair (two) of transducers to function [3, 13]. Because of
that, the pulse echo (PE) evaluation technique is suggested to resolve these complications, since
the technique simply uses single transducer, where it much easier to evaluate bone assessment at the hip
and backbone. However, the accuracy of PE technique is still not powerful compared to TT technique
because of the complex behavior of reflected and backscattered wave relation with inhomogeneity of
cancellous bone. Therefore, using the finite difference time domain simulation (FDTD), Hosokawa
demonstrate that, fast and slow wave can be isolated from reflected/backscattered wave and related more
with bone porosity and this finding might improve the PE technique for bone quality estimation [3, 13-15].
Thus, the objective of this paper is to perform a 2-dimentional (2-D) simulation using PE technique
to examine the relationship of fast and slow wave with structure orientation, porosity, and thicknesses of
cancellous bone models and the result is compared with TT technique. The correlation coefficient (R2
) will
be used to determined the the accuracy of correlation between wave’s parameters and porosity. Fast and slow
wave will be predicted for both measurement techniques via bandlimited deconvolution method. Previously,
no research has used bandlimited deconvolution method to decompose reflected mix waves into two
individual reflected fast and slow waves. Afterwards, the parameters of single modes (mix), fast and slow
waves for both techniques will be compared in term of their correlation coefficient in order to determine
which waves was correlate more with microstructure of bone models.
2. RESEARCH METHOD
2.1. Simulation setup and wave measurement technique
The software SimNDT version 0.43 was used for this analysis [16]. The single Gaussian sine wave
with 1 MHz of frequency was set as output pulse for the transducer and simulation setup was based on TT
and PE technique. Refer to the Figure 1, the size of planar-type transducer was (length) 5.5 mm. The second
transducer for the TT technique was located below the cancellous bone models. For the PE technique,
below the cancellous bone models was air-water boundary that acts as reflector element. The simulation time
for TT and PE was set to 25 and 40 µs, respectively. The 20 Volt peak-to-peaks (Vpp) was set for the input
voltage source. The distance between the bone models and transducer was 8 mm and the absorbing layer with
the thickness of 5 mm was covered the simulation area. Table 1 shows the acoustic and material properties
of bone and water based on paper from Nagatani et al. [17].
Figure 1. Simulation setup diagram
(the blue arrow corresponds to incident wave and red arrow corresponds to reflected wave)
Table 1. Acoustic and material properties
Material Density (g/cm3
) Velocity (m/s)
Bone 2000
Longitudinal: 3500
Shear: 2400
Water 1000
Longitudinal: 1497
Shear: 0
3. ISSN: 1693-6930
TELKOMNIKA Telecommun Comput El Control, Vol. 18, No. 4, August 2020: 1968 - 1975
1970
2.2. 2-D bone models
The 2-D cancellous bone models used in this simulation was originated from paper Gilbert et al. [18].
There are 9 models for each parallel and perpendicular orientation. For each model, there are 6 different
thicknesses, ranging from 5 to 10 mm. The geometric scenario's size of the 2-D bone model's image was set to
170×125 pixel, whereas, 25 pixel/mm was set for the whole simulation area. The porosity level of bone models
was ranging from 30% to 75% and was measured by using ImageJ software based on image color threshold.
Refer to Figure 2, the parallel model was refer to the trabecular shape that was parallel with the direction
of wave propagation (arrow) and vice versa for perpendicular models.
2.3. Bandlimited deconvolution method and wave parameters
There are no attempts yet to implement this method toward the reflected wave. Hence, this paper
can show the feasibility of this method to decompose reflected fast and slow wave. The frequency-dependent
of wave reaction for the bone can be defined by,
𝑌( 𝑓) = 𝑋( 𝑓)[ 𝐻𝑓𝑎𝑠𝑡( 𝑓) + 𝐻𝑠𝑙𝑜𝑤( 𝑓)] (1)
where the 𝑌(𝑓) is the spectrum of the wave propagate through a bone models (mix wave) and 𝑋(𝑓)
is the spectrum of the wave propagate through water only (reference wave). The 𝑓 is the ultrasound
frequency. The transfer function, 𝐻𝑓𝑎𝑠𝑡(𝑓) and 𝐻𝑠𝑙𝑜𝑤(𝑓) for porous structure were considered as two
waves propagating at the same time through an attenuating medium [19] and the detail of the method can be
referred in [11, 12]. In summary (Figure 3), the time domain mix (incident/reflected), 𝑥(𝑡) and reference
wave (incident/reflected), 𝑦(𝑡) was converted to frequency domain signal, 𝑋( 𝑓) and 𝑌(𝑓) via fast Fourier
transform (FFT). Then, 𝐻𝑡𝑜𝑡𝑎𝑙( 𝑓) was calculated by divided 𝑋( 𝑓) by 𝑌( 𝑓). The bone impulse response,
ℎ𝑡𝑜𝑡𝑎𝑙(𝑡) was converted from 𝐻𝑡𝑜𝑡𝑎𝑙(𝑓) by using inverse FFT (IFFT). Then, based on a time threshold of
local minimum (wave envelope) determined by the time shifts parallel to velocities above 1479 m/s
(reference wave), a rectangular time-domain windows will be created. The time threshold above velocities of
reference wave was chosen because the velocity of fast wave was expected to be faster compared to wave
through water only. To estimate the fast wave impulse response, ℎ𝑓𝑎𝑠𝑡(𝑡), the ℎ𝑡𝑜𝑡𝑎𝑙(𝑡) was multiplying
with time domain window with a value equal to one for times before the threshold and zero for times after
the threshold. To obtained slow wave impulse response, ℎ𝑠𝑙𝑜𝑤( 𝑡), ℎ𝑓𝑎𝑠𝑡(𝑡) was subtracted by ℎ𝑡𝑜𝑡𝑎𝑙(𝑡)
due to relation in (1). After that, the slow wave transfer function, 𝐻𝑠𝑙𝑜𝑤(𝑓) was converted from ℎ𝑠𝑙𝑜𝑤( 𝑡)
via FFT and multiply with 𝑋(𝑓) in order to obtained frequency domain’s predicted slow wave, 𝑌𝑠𝑙𝑜𝑤(𝑓).
To get 𝑦𝑠𝑙𝑜𝑤(𝑡) (slow waves in time domain), the IFFT computation will used against the 𝑌𝑠𝑙𝑜𝑤(𝑓) and to
obtain fast wave in time domain, 𝑦𝑓𝑎𝑠𝑡(𝑡), simply subtract 𝑦𝑠𝑙𝑜𝑤(𝑡) with 𝑦(𝑡).
Figure 2. Examples of (a) parallel model and
(b) perpendicular model (black = solid trabecular).
Arrow is the direction of wave
Figure 3. The process flow of the bandlimited
deconvolution method [11, 12]
Wave amplitude (A) (frequency domain peak value of signal amplitude) and frequency dependent
attenuation (β) were considered in the simulation work, where β is given by,
𝛽( 𝑓) =
1
𝐷
[20log 𝑆𝑅( 𝑓) − 20 log 𝑆𝐵(𝑓)] (2)
where 𝑆𝑅(𝑓) and 𝑆𝐵(𝑓) is the spectrum of wave propagate through water and bone models, respectively.
The 𝐷 is the thickness of bone models in cm. The frequency range for the slope 𝛽(𝑓) was from 0.2 MHz to
0.6 MHz and the unit was dB/cm/MHz.
(a) (b)
4. TELKOMNIKA Telecommun Comput El Control
Incident and reflected two waves correlation…. (Muhamad Amin Abd Wahab)
1971
3. RESULTS AND ANALYSIS
3.1. Separation of fast and slow wave
The typical incident wave obtained from TT measurement technique was shown in Figure 4.
For the parallel bone models, at the time of 14 µs, there are two modes of waves, specifically fast and slow
wave. However, only single mode wave was observed for the perpendicular bone model. The slow wave also
has bigger amplitude than the fast wave. This is due to the propagation of the fast wave through solid
trabecular of cancellous bone, and experienced a higher attenuation affect compared to slow wave, where
these waves (slow wave) propagate through of pore part of cancellous bone (lesser attenuation
effect media) [10]. The separation of fast and slow wave in the time domain as shown in Figure 4 for parallel
orientations was in good agreement with previous investigations by Hosokawa [10, 20]. For the incident
wave with parallel orientation, the incident fast and slow wave were estimated based on observation in time
domain, not using bandlimited deconvolution.
Figure 5 (a) shows an example of the bone impulse response, ℎ𝑡𝑜𝑡𝑎𝑙(𝑡) or ℎ(𝑡) of the TT
measurement technique for the perpendicular orientation of bone models. The |ℎ(𝑡)| was the envelope of
ℎ𝑡𝑜𝑡𝑎𝑙(𝑡). The time threshold that split the bone impulse response into ℎ𝑓𝑎𝑠𝑡(𝑡) (left) and ℎ𝑠𝑙𝑜𝑤(𝑡) (right)
was specified by the vertical dashed line (red). The arrival time of incident fast wave was approximately
0.38 µs (tFast) earlier, whereas the arrival time of incident slow wave (estimated by yslow(t)) was 0.66 µs
(tSlow) late compare to incident reference wave adjustment measurement arrival time (i.e., time, tRef = 0 µs).
Figure 5 (b) shows 𝑦𝑠𝑙𝑜𝑤(𝑡), incident mix (red + blue), first and second waves estimated using
bandlimited deconvolution method. The 𝑦𝑠𝑙𝑜𝑤(𝑡) was used to estimate the possibility of time-domain
location of slow wave from mix wave. Then, the fast wave was obtained by subtracted the slow wave from
the mix wave. Referring to Figure 6 (a) and Table 2 for the porosity value of 67%, the amplitude of incident
mix wave was 0.82 V. The amplitude of incident slow wave was higher (0.64 V) than the incident fast wave
(0.22 V). Previous work by Nagasaki et al. [4], Kawasaki et al. [5], Otani [6], Cardoso et al. [7]
and Nelson et al. [8] also report the same findings in terms of amplitude ratio of fast and slow waves.
Moreover, the oscillation frequency of ℎ𝑠𝑙𝑜𝑤(𝑡) (based on |ℎ( 𝑡)|) was higher than that for
ℎ𝑓𝑎𝑠𝑡(𝑡) as shown in Figure 5 (a) and the slope of attenuation for the incident slow wave (91 dB/cm/MHz)
was lower than that for the incident fast wave (118 dB/cm/MHz) which also shown in Figure 6 (b) and
Table 2. The same behaviors of fast and slow waves were also reported from the previous research [11].
The relation of the lower frequency and higher attenuation of the fast wave is due to high frequency
component of wave affected more by attenuation, specifically absorption compared to the low frequency
component [21]. Nonetheless, some situation exhibits amplitude of fast wave bigger or similar with slow
wave depends on density and the acoustic properties of bone phantom or material used [22, 23].
Figure 4. Example of incident wave propagates through parallel and perpendicular orientation
(a) (b)
Figure 5. Examples of (a) transfer function and (b) incident first and second wave for the perpendicular
orientation bone models (porosity = 67%, thickness = 5 mm)
5. ISSN: 1693-6930
TELKOMNIKA Telecommun Comput El Control, Vol. 18, No. 4, August 2020: 1968 - 1975
1972
Table 2. Data related to Figure 6
P (%)
A
(V)
β
(dB/cm/MHz)
Mix Fast Slow Mix Fast Slow
33 0.32 0.25 0.09 56 95 124
36 0.48 0.26 0.23 70 95 115
37 0.41 0.43 0.03 69 57 124
49 0.38 0.22 0.17 63 80 79
53 0.77 0.17 0.62 57 101 88
54 0.80 0.16 0.64 52 113 87
67 0.82 0.22 0.64 42 118 91
71 1.30 0.29 1.08 49 118 85
74 1.77 0.33 1.47 51 116 82
P = Porosity, A = Amplitude and β = Attenuation
Figure 6. Example of (a) amplitude and
(b) attenuation versus porosity of incident wave
3.2. Correlation of the wave parameters with various porosities and thicknesses
Referring to Table 3 – TT – parallel orientation sections, the amplitude of the incident slow wave
and mix (AIslow and AImix) increased when porosity increases for all thickness. The correlation coefficient for
both waves also seems to decrease when thickness decrease. However, there is no or low correlation between
attenuation of the incident mix and slow waves (βImix and βIslow) and porosity. The amplitude of incident fast
waves, AIfast decrease when porosity increase and the correlation coefficient increase when thickness
decreases. The attenuation of the incident fast wave, βIfast increases with porosity with consistent and slightly
significant correlation coefficient for all thicknesses.
In the Table 3 – TT – perpendicular orientation, the AImix and AIslow increase when porosity increases
while βImix and βIslow decrease when porosity increase. Both incident mix and slow waves parameters show
high correlation coefficient and consistent for all thicknesses. Nevertheless, the AIfast also increase when
porosity increases for all thicknesses except at the thickness of 5 mm. The correlation coefficient also decreases
when thickness increase. In terms of βIfast, this parameter shows an increasing trend versus porosity with
slightly significant and consistent correlation coefficient for all thicknesses. Figures 6 (a) and (b) show examples
of the correlation between the two parameters (amplitude and attenuation of incident wave) and porosity for
parallel orientation of bone models with porosity value of 67% and thickness of 5 mm.
As shown in Table 3 – PE – parallel orientations, the amplitude of the reflected mix wave, ARmix
decrease when porosity increases. However, the correlation coefficient is slightly low for all thicknesses.
The attenuation of the reflected mix wave, βRmix increase when porosity increases. The correlation coefficient
was slightly significant at the thickness of 5 mm, but low to the rest of thicknesses. In addition, the amplitude
of the reflected fast wave, ARfast decreases when porosity increases and the correlation coefficient was slightly
significant. The ARfast also seems not affected by changes of thickness. In terms of attenuation of the reflected
fast wave, βRfast increase when porosity increase with low correlation at the thicker bone models,
but the correlation coefficient increase when thickness decreases. On the other hand, both parameters of
the reflected slow wave (ARslow and βRslow) show no correlation with porosity. Refer to Table 3 – PE –
perpendicular orientations, all wave amplitudes show low correlation versus porosity. The βRmix and βRslow
also show low correlation versus porosity. However, the βRfast shows negative trends versus porosity with
slightly significant correlation coefficient versus porosity for all thicknesses.
The decreasing trend of AIfast and ARfast for parallel orientation versus porosity corresponds to
the behavior of fast wave was reported by Hosokawa et al. [10], Kawasaki et al. [5] and Otani [6]. As mention
previously, the fast wave propagates mainly through solid trabecular. When porosity increase, the solid
trabecular decrease, thereby, reduces the medium for fast wave to propagate which contribute to low amplitude.
The opposite happens to the increasing trend of AIslow for parallel orientation versus porosity which due to
the slow wave propagates through pore part of porous structure. When trabecular spacing and pore size growth,
it boosts the flow of the fluid, which reduces the opposition of wave propagation, resulting in decreasing
of the attenuation effect [24]. Previous research by Hosokawa et al. [10], Kawasaki et al. [5] and Otani [6] also
reported the same outcome for the slow wave.
For the parallel orientation, the increasing trend of βIfast and BRfast was corresponded with
the decreasing trend of AIfast and ARfast. When the amplitude decreases, the attenuation was expected to
increase. Nevertheless, Hoffman et al. [25] described that, due to bone sonometry effect, the fast wave slope of
attenuation decrease when porosity increases. Moreover, Cardoso et al. [7] specifies that, the the fast wave slope
of attenuation was displaying parabolic manners versus porosity, which due to domination of slow wave slope
of attenuation against most of the frequency ranges, mainly for the cancellous bone with higher porosity level.
In this paper, the parallel orientation has continuity of connection between solid trabecular might enhance
the propagation of reflected and incident fast wave and these waves usually has lower frequency content.
40 60 80
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
R2
= 0.61
R2
= 0.67
R2
= 0.55
R2
= 0.01
R2
= 0.83
Amplitude(V)
Porosity (%)
R2
= 0.77
40 60 80
40
50
60
70
80
90
100
110
120
130
Attenuation(dB/cm/MHz)
Porosity (%)
Mix wave
Fast wave
Slow wavea) b)
6. TELKOMNIKA Telecommun Comput El Control
Incident and reflected two waves correlation…. (Muhamad Amin Abd Wahab)
1973
Because of that, the frequency of ranges (0.2 – 0.6 MHz) for the slope of attenuation might be dominated by fast
wave and causing βIslow and βRslow to show low correlation with porosity. Furthermore, for perpendicular
orientation, the βIslow shows a behavior similar with slow wave as found from previous research by Hoffman et
al. [25] and corresponded with the increasing AIslow versus porosity. The high correlation coefficient of βIslow
also supports the claim that slow wave may be dominating the incident wave propagation for perpendicular
orientation. Same goes to ARfast for parallel orientation, which dominate the reflected wave propagation.
Because of that, the ARfast and ARmix show similar trend versus porosity compared to ARslow.
Table 3. Overall result of correlation coefficient for TT and PE measurement technique
P D BO
Correlation Coefficient, R2
BO
Correlation Coefficient, R2
TT (I) PE (R) TT (I) PE (R)
M F S M F S M F S M F S
A 10 ∥ 0.50 -0.28 0.51 -0.47 -0.57 0.02 ⊥ 0.80 0.51 0.81 -0.01 -0.02 0.01
9 0.33 -0.21 0.51 -0.27 -0.42 0.05 0.79 0.57 0.77 -0.04 0.19 -0.03
8 0.32 -0.51 0.45 -0.28 -0.37 0.01 0.80 0.39 0.81 -0.05 -0.01 -0.02
7 0.18 -0.74 0.32 -0.28 -0.29 0.02 0.77 0.31 0.79 -0.04 -0.02 -0.03
6 0.12 -0.77 0.36 -0.35 -0.36 -0.07 0.67 0.01 0.70 -0.10 -0.16 -0.02
5 0.01 -0.64 0.32 -0.33 -0.37 -0.02 0.78 -0.01 0.83 -0.22 -0.51 -0.01
β 10 ∥ -0.08 0.57 0.02 0.33 0.37 -0.06 ⊥ -0.92 0.41 -0.76 -0.01 0.45 0.02
9 -0.01 0.58 -0.20 0.09 0.44 -0.13 -0.45 0.48 -0.50 0.05 0.47 0.20
8 -0.01 0.40 -0.20 0.07 0.43 -0.01 -0.64 0.49 -0.76 0.11 0.40 0.17
7 -0.01 0.68 -0.26 0.13 0.71 0.01 -0.63 0.41 -0.79 0.15 0.60 0.10
6 -0.18 0.45 0.02 0.28 0.71 0.01 -0.69 0.65 -0.55 0.10 0.46 -0.01
5 -0.01 0.51 -0.06 0.58 0.57 0.08 -0.61 0.55 -0.67 0.36 0.32 -0.02
• BO = Bone orientation, ∥ = parallel, ⊥ = perpendicular, P = Parameters, D = Thickness (mm), A = Amplitude, β = Attenuation, M
= Mix wave, F = Fast wave, and S = Slow wave.
• Sign (±) specify positive or negative trend versus porosity
• n = 9; Very significant: R2
≥ 0.798, p ≤ 0.01; Significant: R2
≥ 0.666, p ≤ 0.05; Slightly significant: R2
≥ 0.348, p ≤ 0.1
The trend of βIfast is not parallel with the trends of AIfast for perpendicular orientation. However,
the trend of βIfast for perpendicular orientation was the same as βIfast for parallel orientation. This indicates
that, the slope of attenuation not influenced by amplitude. Not only that, the βRfast for parallel
and perpendicular orientations also behaves the same as βIfast. This behavior might be due to scattering effect
from acoustic impedance mismatch and inhomogeneity of trabecular structure [26, 27] especially at high
porosity was affected fast wave, thereby, showing an increasing trend versus porosity for attenuation of fast
wave, despite some situation, where the behavior of the amplitude of fast wave not correspond with the
attenuation. Meanwhile, absorption, which was caused by natural absorption in the solid and liquid phase (bone
marrow or water) [26] may affect slow wave. The total attenuation mostly contributes by scattering effect
compared to absorption at the higher porosity bone models.
In terms of performance of the correlation coefficient, overall result shows that the incident wave has
good correlation with porosity compared to reflected wave. This might be due to propagation loss of reflected
wave suffered. The reflected waves propagate through bone, reflected at the boundary between air and water
was weakened the reflected wave. After that, these waves propagate again through bone before reaching
transducer. Not only that, the reflected wave also may be mixed with scattered wave inside a cancellous bone
structure (produced by the propagation of incident wave) and deteriorate the reflected wave.
Previous research by Nagatani et al. [17] shows that the attenuation of fast wave increases when
thickness increases and then the attenuation decrease to certain value and become constant. It specifies that fast
wave required certain thickness to generate when ultrasound waves propagate through cancellous bone [17].
Nelson et al. [28] indicate that, attenuation in frequency domain (slope of attenuation) of fast and slow wave
was constant for cancellous bone thickness from 5 mm to 15 mm. Moreover, in time domain analysis (ratio
of amplitude between sample and reference wave), the attenuation of fast wave decrease considerably when
thickness increase while attenuation of slow wave decrease slightly. This behavior occurs for the attenuation in
time domain because of the nature of broadband pulse [28]. This behavior also might be the reason why
correlation coefficient of AIfast for parallel orientation decreases when thickness increases. At the lesser
thickness, the fast wave shows a clear difference of amplitude for each porosity value. But, when thickness
increases, the difference of amplitude for each value is reduce, hence, causing less clear of trends as well
correlation coefficient to decrease. Same goes to the correlation coefficient of AIfast for perpendicular
orientation which seems to show trend changes from increase to decrease when thickness decrease.
Besides, the βIfast and βRfast for parallel and perpendicular orientation also shows consistent in
correlation coefficient when the thickness increases. This shows that, the attenuation in frequency domain (slope
7. ISSN: 1693-6930
TELKOMNIKA Telecommun Comput El Control, Vol. 18, No. 4, August 2020: 1968 - 1975
1974
of attenuation) not really affected by the thickness. Next, the decreasing of the correlation coefficient of AIslow
for parallel orientation when thickness increase may be due to increases of solid trabecular which affected
amplitude of slow wave. But, the correlation coefficient of βIslow for parallel and perpendicular was assumed
consistent despite for low correlation for parallel orientation. However, the correlation coefficient of AIslow for
perpendicular orientation appears consistent when thickness increases. This behavior may be due to slow wave
domination and the effect of attenuation in the time domain which not affects much slow wave as found by
Nelson et al [28]. For the parallel orientation, the correlation coefficient of ARfast decreases slightly when
thickness increases, where the behavior was a bit different compared to AIfast. The domination of ARfast as
mention previously may contribute such behavior of this wave for all thicknesses.
However, the interaction between reflection wave and cancellous bone needs to be further investigated
to better understand its behavior. The propagation loss and multiple scattering may be involved and need to be
solved before broadband deconvolution method was applied to reflected wave and perhaps can produce a clear
correlation between reflected fast and slow wave and porosity. The 2D simulation environment may not be as
powerful as 3D simulation and real experiment, hence, the result might be a bit different with other research.
4. CONCLUSION
In conclusion, the reflected fast and slow wave was possible to be separated using bandlimited
deconvolution, where there was no attempt before by other researchers to decompose the reflected wave using
this method. Besides, this paper also shows a behavior of the reflected fast and slow waves, which might be
useful to other researchers to further investigate as the purpose to improved accuracy of bone estimation using
pulse echo technique. Moreover, the attenuation of incident and reflected fast wave for both bone orientations
showing a similar increases trend versus porosity with a slightly good correlation coefficient. This was due to
solid structure of bone was related to fast wave. The incident slow waves dominated the wave propagation for
perpendicular orientation for both parameters and showing good correlation with porosity. The behavior of slow
wave indicates that, pore part of the bone was related with this wave. In addition, the thickness of bone models
clearly affected incident fast and slow wave in terms of amplitude but less effect in terms of attenuation which is
good agreement with previous research, where attenuation behave constantly when thickness increase.
The orientation of bone models also affected both reflected and incident fast and slow waves. The complex
behavior of reflected wave interacts with inhomogeneity of cancelous bone models still difficult to interpret due
to propagation loss suffered by these waves. However, the accuracy of bone health evaluation for pulse echo
technique might improve if considering two modes wave instead of single mode especially fast wave.
ACKNOWLEDGEMENT
The researchers would like to thank Universiti Teknologi Malaysia (UTM) and MOHE for funding
the study under grant Vot Q.J13000.2551.21H49 and Q.J13000.3001.01M13.
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