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Nurhazimah Nazmi
Engineering Materials and Structures (eMast) iKohza, Malaysia-Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia

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Journal article
Published: 27 August 2021 in Materials
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Polymer composites have been widely used as damping materials in various applications due to the ability of reducing the vibrations. However, the environmental and surrounding thermal exposure towards polymer composites have affected their mechanical properties and lifecycle. Therefore, this paper presents the effect of material-temperature dependence on the loss factor and phase shift angle characteristics. Two types of unageing and aging silicone-rubber-based magnetorheological elastomer (SR-MRE) with different concentrations of carbonyl iron particles (CIPs), 30 and 60 wt%, are utilized in this study. The morphological, magnetic, and rheological properties related to the loss factor and phase shift angle are characterized using a low-vacuum scanning electron microscopy, and vibrating sample magnetometer and rheometer, respectively. The morphological analysis of SR-MRE consisting of 30 wt% CIPs revealed a smoother surface area when compared to 60 wt% CIPs after thermal aging due to the improvement of CIPs dispersion in the presence of heat. Nevertheless, the rheological analysis demonstrated inimitable rheological properties due to different in-rubber structures, shear deformation condition, as well as the influence of magnetic field. No significant changes of loss factor occurred at a low CIPs concentration, whilst the loss factor increased at a higher CIPs concentration. On that basis, it has been determined that the proposed changes of the polymer chain network due to the long-term temperature exposure of different concentrations of CIPs might explain the unique rheological properties of the unaged and aged SR-MRE.

ACS Style

Siti Aishah Abdul Aziz; Saiful Amri Mazlan; Ubaidillah Ubaidillah; Norzilawati Mohamad; Michal Sedlacik; Nur Azmah Nordin; Nurhazimah Nazmi. Loss Factor Behavior of Thermally Aged Magnetorheological Elastomers. Materials 2021, 14, 4874 .

AMA Style

Siti Aishah Abdul Aziz, Saiful Amri Mazlan, Ubaidillah Ubaidillah, Norzilawati Mohamad, Michal Sedlacik, Nur Azmah Nordin, Nurhazimah Nazmi. Loss Factor Behavior of Thermally Aged Magnetorheological Elastomers. Materials. 2021; 14 (17):4874.

Chicago/Turabian Style

Siti Aishah Abdul Aziz; Saiful Amri Mazlan; Ubaidillah Ubaidillah; Norzilawati Mohamad; Michal Sedlacik; Nur Azmah Nordin; Nurhazimah Nazmi. 2021. "Loss Factor Behavior of Thermally Aged Magnetorheological Elastomers." Materials 14, no. 17: 4874.

Journal article
Published: 11 August 2021 in Micromachines
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This paper presents the effect of the micro-sized particles on the storage modulus and durability characteristics of magnetorheological elastomers (MREs). The initial phase of the investigation is to determine any associations among the microparticles’ weight percent fraction (wt%), structure arrangement, and the storage modulus of MRE samples. In order to carry out this, both isotropic and anisotropic types of MRE samples consisting of the silicone rubber matrix and 50, 60, 70, 75, and 80 wt% microparticles of carbonyl iron fractions are prepared. It is identified from the magneto-rheometer that the increase in storage modulus and decrease in linear viscoelastic region limit are observed in varying consistency depending on wt% and particle arrangement. The consistency of this dependency feature is highlighted by superimposing all of the graphs plotted to create the proposed the samples’ behavior model. In response to increasing magnetic stimulation, a sample of 70 wt% microparticles with an isotropic arrangement is found to be significant and stable. The experimentally defined fraction is then used for the durability test as the second phase of the investigation. During this phase, the durability evaluation is subjected to stress relaxation for an extended period of time. After undergoing durability testing, storage modulus performance is decreased by 0.7–13% at various magnetic stimulation levels. This result directly indicates that the storage modulus characteristics of different forms of MRE are sensitive to the different iron particle fractions’ and microparticles’ alignment. Therefore, important treatments to alter the storage modulus can be undertaken before the practical implementation to accommodate any desired performance of MRE itself and MRE application systems.

ACS Style

Mohd Aidy Faizal Johari; Saiful Amri Mazlan; Nur Azmah Nordin; U Ubaidillah; Siti Aishah Abdul Aziz; Nurhazimah Nazmi; Norhasnidawani Johari; Seung-Bok Choi. The Effect of Microparticles on the Storage Modulus and Durability Behavior of Magnetorheological Elastomer. Micromachines 2021, 12, 948 .

AMA Style

Mohd Aidy Faizal Johari, Saiful Amri Mazlan, Nur Azmah Nordin, U Ubaidillah, Siti Aishah Abdul Aziz, Nurhazimah Nazmi, Norhasnidawani Johari, Seung-Bok Choi. The Effect of Microparticles on the Storage Modulus and Durability Behavior of Magnetorheological Elastomer. Micromachines. 2021; 12 (8):948.

Chicago/Turabian Style

Mohd Aidy Faizal Johari; Saiful Amri Mazlan; Nur Azmah Nordin; U Ubaidillah; Siti Aishah Abdul Aziz; Nurhazimah Nazmi; Norhasnidawani Johari; Seung-Bok Choi. 2021. "The Effect of Microparticles on the Storage Modulus and Durability Behavior of Magnetorheological Elastomer." Micromachines 12, no. 8: 948.

Journal article
Published: 05 August 2021 in Materials
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Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those with viscoelastic matrices. Heretofore, the characteristics of shear bands in terms of formation, physical evolution, and response to stress distribution at the localized region have gone largely unnoticed and unexplored. Notwithstanding these limitations, atomic force microscopy (AFM) has been used to explore the nature of shear band deformation in MR materials during stress relaxation. Stress relaxation at a constant low strain of 0.01% and an oscillatory shear of defined test duration played a major role in the creation of the shear band. In this analysis, the localized area of the study defined shear bands as varying in size and dominantly deformed in the matrix with no evidence of inhibition by embedded carbonyl iron particles (CIPs). The association between the shear band and the adjacent zone was further studied using in-phase imaging of AFM tapping mode and demonstrated the presence of localized affected zone around the shear band. Taken together, the results provide important insights into the proposed shear band deformation zone (SBDZ). This study sheds a contemporary light on the contentious issue of amorphous shear band deformation behavior and makes several contributions to the current literature.

ACS Style

Mohd Johari; Asmawan Sarman; Saiful Mazlan; Ubaidillah U; Nur Nordin; Siti Abdul Aziz; Norhasnidawani Johari; Nurhazimah Nazmi; Shahir Mohd Yusuf. An Insight into Amorphous Shear Band in Magnetorheological Solid by Atomic Force Microscope. Materials 2021, 14, 4384 .

AMA Style

Mohd Johari, Asmawan Sarman, Saiful Mazlan, Ubaidillah U, Nur Nordin, Siti Abdul Aziz, Norhasnidawani Johari, Nurhazimah Nazmi, Shahir Mohd Yusuf. An Insight into Amorphous Shear Band in Magnetorheological Solid by Atomic Force Microscope. Materials. 2021; 14 (16):4384.

Chicago/Turabian Style

Mohd Johari; Asmawan Sarman; Saiful Mazlan; Ubaidillah U; Nur Nordin; Siti Abdul Aziz; Norhasnidawani Johari; Nurhazimah Nazmi; Shahir Mohd Yusuf. 2021. "An Insight into Amorphous Shear Band in Magnetorheological Solid by Atomic Force Microscope." Materials 14, no. 16: 4384.

Article
Published: 16 April 2021 in Journal of Polymer Science
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In this work, carbonyl iron particles (CIP) was grafted with polystyrene coating on its surface via polymerization method, and the coated‐CIPs were then embedded into a silicone rubber with the ratio of 70:30 of CIP to silicone rubber in order to enhance the rheological properties of magnetorheological elastomer (MRE) in terms of lower initial storage modulus and higher MR effect. By using field emission scanning electron microscopy (FESEM) that is equipped with the energy dispersive X‐ray spectroscopy for elemental analysis, it was observed that elements of C, N, O, Si, Fe, Br, Cu, and Sn were detected, confirming that the coating layer has been successfully developed on the CIP. Additionally, the investigation of the rheological characteristics was conducted at 25°C with three different sweep conditions using rheometer MCR 302. Firstly the strain amplitude was swept from 0.001% to 10% strain with 1 Hz frequency. Then, the frequency was varied from 1 Hz to 100 Hz under 0.01% strain at an applied current of 0–5 A. Lastly, the current was swept from 0 to 5 A under 0.01% strain amplitude and 1 Hz excitation frequency. It was discovered that the storage modulus of the polystyrene‐coated CIP MRE is lower than that of uncoated‐CIP MRE in all three sweep profiles. Advantageously, the magnetorheological (MR) effect of the coated‐CIP MRE sample is higher than that of the uncoated‐CIP MRE by 28.04%. Moreover, it was found that the coated‐CIP MRE exhibited higher damping behavior with more than 0.14 loss factor than 0.12 loss factor of the uncoated sample. The dimensional stability of polystyrene coating on the CIP was an attributing factor to this enhanced damping behavior of the coated‐CIP MRE. Thus, it became clear that the polystyrene‐coated CIP embedment in MRE is more desirable than that of MRE with uncoated CIP.

ACS Style

Siti Khumaira Mohd Jamari; Nur Azmah Nordin; U. Ubaidillah; Siti Aishah Abdul Aziz; Saiful Amri Mazlan; Nurhazimah Nazmi. Enhancement of the rheological properties of magnetorheological elastomer via polystyrene‐grafted carbonyl iron particles. Journal of Polymer Science 2021, 138, 50860 .

AMA Style

Siti Khumaira Mohd Jamari, Nur Azmah Nordin, U. Ubaidillah, Siti Aishah Abdul Aziz, Saiful Amri Mazlan, Nurhazimah Nazmi. Enhancement of the rheological properties of magnetorheological elastomer via polystyrene‐grafted carbonyl iron particles. Journal of Polymer Science. 2021; 138 (34):50860.

Chicago/Turabian Style

Siti Khumaira Mohd Jamari; Nur Azmah Nordin; U. Ubaidillah; Siti Aishah Abdul Aziz; Saiful Amri Mazlan; Nurhazimah Nazmi. 2021. "Enhancement of the rheological properties of magnetorheological elastomer via polystyrene‐grafted carbonyl iron particles." Journal of Polymer Science 138, no. 34: 50860.

Journal article
Published: 28 February 2021 in Sensors
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Magnetoactive (MA) foam, with its tunable mechanical properties and magnetostriction, has the potential to be used for the development of soft sensor technology. However, researchers have found that its mechanical properties and magnetostriction are morphologically dependent, thereby limiting its capabilities for dexterous manipulation. Thus, in this work, MA foam was developed with additional capabilities for controlling its magnetostriction, normal force, storage modulus, shear stress and torque by manipulating the concentration of carbonyl iron particles (CIPs) and the magnetic field with regard to morphological changes. MA foams were prepared with three weight percentages of CIPs, namely, 35 wt.%, 55 wt.% and 75 wt.%, and three different modes, namely, zero shear, constant shear and various shears. The results showed that the MA foam with 75 wt.% of CIPs enhanced the normal force sensitivity and positive magnetostriction sensitivity by up to 97% and 85%, respectively. Moreover, the sensitivities of the storage modulus, torque and shear stress were 8.97 Pa/mT, 0.021 µN/mT, and 0.0096 Pa/mT, respectively. Meanwhile, the magnetic dipolar interaction between the CIPs was capable of changing the property of MA foam from a positive to a negative magnetostriction under various shear strains with a low loss of energy. Therefore, it is believed that this kind of highly sensitive MA foam can potentially be implemented in future soft sensor systems.

ACS Style

Rizuan Norhaniza; Saiful Mazlan; Ubaidillah Ubaidillah; Michal Sedlacik; Siti Aziz; Nurhazimah Nazmi; Koji Homma; Shuib Rambat. Sensitivities of Rheological Properties of Magnetoactive Foam for Soft Sensor Technology. Sensors 2021, 21, 1660 .

AMA Style

Rizuan Norhaniza, Saiful Mazlan, Ubaidillah Ubaidillah, Michal Sedlacik, Siti Aziz, Nurhazimah Nazmi, Koji Homma, Shuib Rambat. Sensitivities of Rheological Properties of Magnetoactive Foam for Soft Sensor Technology. Sensors. 2021; 21 (5):1660.

Chicago/Turabian Style

Rizuan Norhaniza; Saiful Mazlan; Ubaidillah Ubaidillah; Michal Sedlacik; Siti Aziz; Nurhazimah Nazmi; Koji Homma; Shuib Rambat. 2021. "Sensitivities of Rheological Properties of Magnetoactive Foam for Soft Sensor Technology." Sensors 21, no. 5: 1660.

Journal article
Published: 09 February 2021 in Fluids
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Coronavirus disease 2019 (Covid-19) has been identified as being transmitted among humans with droplets from breath, cough, and sneezes. Understanding the droplets’ behavior can be critical information to avoid disease transmission, especially while designing a device deals with human air respiratory. Although various studies have provided enormous computational fluid simulations, most cases are too specific and quite challenging to combine with other similar studies directly. Therefore, this paper proposes a systematic approach to predict the droplet behavior for coughing cases using machine learning. The approach consists of three models, which are droplet generator, mask model, and free droplet model modeled using feedforward neural network (FFNN). The evaluation has shown that the three FFNNs models’ accuracies are relatively high, with R-values of more than 0.990. The model has successfully predicted the evaporation effect on the diameter reduction and the completely evaporated state, which can be considered unlearned cases for machine learning models. The predicted horizontal distance pattern also agrees with the data in the literature. In summary, the proposed approach has demonstrated the capability to predict the diameter pattern according to the experimental or previous work data at various mask face types.

ACS Style

Irfan Bahiuddin; Setyawan Wibowo; M. Syairaji; Jimmy Putra; Cahyo Pandito; Ahdiar Maulana; Rian Prastica; Nurhazimah Nazmi. A Systematic Approach to Predict the Behavior of Cough Droplets Using Feedforward Neural Networks Method. Fluids 2021, 6, 76 .

AMA Style

Irfan Bahiuddin, Setyawan Wibowo, M. Syairaji, Jimmy Putra, Cahyo Pandito, Ahdiar Maulana, Rian Prastica, Nurhazimah Nazmi. A Systematic Approach to Predict the Behavior of Cough Droplets Using Feedforward Neural Networks Method. Fluids. 2021; 6 (2):76.

Chicago/Turabian Style

Irfan Bahiuddin; Setyawan Wibowo; M. Syairaji; Jimmy Putra; Cahyo Pandito; Ahdiar Maulana; Rian Prastica; Nurhazimah Nazmi. 2021. "A Systematic Approach to Predict the Behavior of Cough Droplets Using Feedforward Neural Networks Method." Fluids 6, no. 2: 76.

Journal article
Published: 10 December 2020 in Materials
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Conventional polyurethane foam has non-tunable sound absorption properties. Here, a magneto-induced foam, called magnetorheological (MR) foam, was fabricated with the feature of being able to tune sound absorption properties, primarily from the middle- to higher-frequency ranges. Three different samples of MR foams were fabricated in situ by varying the concentration of Carbonyl Iron Particles (CIPs) (0, 35, and 75 wt.%). The magnetization properties and tunable sound absorption characteristics were evaluated. From the magnetic saturation properties, the results showed very narrow and small coercivity of hysteresis loops relative to the soft magnetic properties of the CIPs. MR foam with 75 wt.% CIPs showed a higher magnetic saturation at 91.350 emu/g compared to MR foam with 35 wt.% CIPs at 63.896 emu/g. For tunable sound absorption testing, the effect of ‘shifting’ to higher frequency was also observed when the magnetic field was applied, which was ~10 Hz for MR foam with 35 wt.% CIPs and ~130 Hz for MR foam with 75 wt.% CIPs. As the latest evolution of semi-active noise control materials, the results from this study are valuable guidance for the advancement of MR-based devices.

ACS Style

Noor Sahirah Muhazeli; Nur Azmah Nordin; Ubaid Ubaidillah; Saiful Amri Mazlan; Siti Aishah Abdul Aziz; Nurhazimah Nazmi; Iwan Yahya. Magnetic and Tunable Sound Absorption Properties of an In-Situ Prepared Magnetorheological Foam. Materials 2020, 13, 5637 .

AMA Style

Noor Sahirah Muhazeli, Nur Azmah Nordin, Ubaid Ubaidillah, Saiful Amri Mazlan, Siti Aishah Abdul Aziz, Nurhazimah Nazmi, Iwan Yahya. Magnetic and Tunable Sound Absorption Properties of an In-Situ Prepared Magnetorheological Foam. Materials. 2020; 13 (24):5637.

Chicago/Turabian Style

Noor Sahirah Muhazeli; Nur Azmah Nordin; Ubaid Ubaidillah; Saiful Amri Mazlan; Siti Aishah Abdul Aziz; Nurhazimah Nazmi; Iwan Yahya. 2020. "Magnetic and Tunable Sound Absorption Properties of an In-Situ Prepared Magnetorheological Foam." Materials 13, no. 24: 5637.

Journal article
Published: 18 October 2019 in Applied Sciences
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This paper aims to present a preliminary study of control reference parameters for stance assistance among different subjects and walking speeds using a passive-controlled ankle foot orthosis. Four young male able-bodied subjects with varying body mass indexes (23.842 ± 4.827) walked in three walking speeds of 1, 3, and 5 km/h. Two control references, average ankle torque (aMa), and ankle angular velocity (aω), which can be implemented using a magnetorheological brake, were measured. Regression analysis was conducted to identify suitable control references in the three different phases of the stance. The results showed that aω has greater correlation (p) with body mass index and walking speed compared to aMa in the whole stance phase (p1(aω) = 0.666 > p1(aMa) = 0.560, p2(aω) = 0.837 > p2(aMa) = 0.277, and p3(aω) = 0.839 > p3(aMa) = 0.369). The estimation standard error (Se) of the aMa was found to be generally higher than of aω (Se1(aMa) = 2.251 > Se1(aω) = 0.786, Se2(aMa) = 1.236 > Se2(aω) = 0.231, Se3(aMa) = 0.696 < Se3(aω) = 0.755). Future studies should perform aω estimation based on body mass index and walking speed, as suggested by the higher correlation and lower standard error as compared to aMa. The number of subjects and walking speed scenarios should also be increased to reduce the standard error of control reference parameters estimation.

ACS Style

Dimas Adiputra; Mohd Azizi Abdul Rahman; Ubaidillah; Saiful Amri Mazlan; Nurhazimah Nazmi; Muhammad Kashfi Shabdin; Jun Kobayashi; Mohd Hatta Mohammed Ariff. Control Reference Parameter for Stance Assistance Using a Passive Controlled Ankle Foot Orthosis—A Preliminary Study. Applied Sciences 2019, 9, 4416 .

AMA Style

Dimas Adiputra, Mohd Azizi Abdul Rahman, Ubaidillah, Saiful Amri Mazlan, Nurhazimah Nazmi, Muhammad Kashfi Shabdin, Jun Kobayashi, Mohd Hatta Mohammed Ariff. Control Reference Parameter for Stance Assistance Using a Passive Controlled Ankle Foot Orthosis—A Preliminary Study. Applied Sciences. 2019; 9 (20):4416.

Chicago/Turabian Style

Dimas Adiputra; Mohd Azizi Abdul Rahman; Ubaidillah; Saiful Amri Mazlan; Nurhazimah Nazmi; Muhammad Kashfi Shabdin; Jun Kobayashi; Mohd Hatta Mohammed Ariff. 2019. "Control Reference Parameter for Stance Assistance Using a Passive Controlled Ankle Foot Orthosis—A Preliminary Study." Applied Sciences 9, no. 20: 4416.

Review
Published: 28 January 2019 in Actuators
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In the past decade, advanced technologies in robotics have been explored to enhance the rehabilitation of post-stroke patients. Previous works have shown that gait assistance for post-stroke patients can be provided through the use of robotics technology in ancillary equipment, such as Ankle Foot Orthosis (AFO). An AFO is usually used to assist patients with spasticity or foot drop problems. There are several types of AFOs, depending on the flexibility of the joint, such as rigid, flexible rigid, and articulated AFOs. A rigid AFO has a fixed joint, and a flexible rigid AFO has a more flexible joint, while the articulated AFO has a freely rotating ankle joint, where the mechanical properties of the AFO are more controllable compared to the other two types of AFOs. This paper reviews the control of the mechanical properties of existing AFOs for gait assistance in post-stroke patients. Several aspects that affect the control of the mechanical properties of an AFO, such as the controller input, number of gait phases, controller output reference, and controller performance evaluation are discussed and compared. Thus, this paper will be of interest to AFO researchers or developers who would like to design their own AFOs with the most suitable mechanical properties based on their application. The controller input and the number of gait phases are discussed first. Then, the discussion moves forward to the methods of estimating the controller output reference, which is the main focus of this study. Based on the estimation method, the gait control strategies can be classified into subject-oriented estimations and phase-oriented estimations. Finally, suggestions for future studies are addressed, one of which is the application of the adaptive controller output reference to maximize the benefits of the AFO to users.

ACS Style

Dimas Adiputra; Nurhazimah Nazmi; Irfan Bahiuddin; Ubaidillah Ubaidillah; Fitrian Imaduddin; Mohd Azizi Abdul Rahman; Saiful Amri Mazlan; Hairi Zamzuri. A Review on the Control of the Mechanical Properties of Ankle Foot Orthosis for Gait Assistance. Actuators 2019, 8, 10 .

AMA Style

Dimas Adiputra, Nurhazimah Nazmi, Irfan Bahiuddin, Ubaidillah Ubaidillah, Fitrian Imaduddin, Mohd Azizi Abdul Rahman, Saiful Amri Mazlan, Hairi Zamzuri. A Review on the Control of the Mechanical Properties of Ankle Foot Orthosis for Gait Assistance. Actuators. 2019; 8 (1):10.

Chicago/Turabian Style

Dimas Adiputra; Nurhazimah Nazmi; Irfan Bahiuddin; Ubaidillah Ubaidillah; Fitrian Imaduddin; Mohd Azizi Abdul Rahman; Saiful Amri Mazlan; Hairi Zamzuri. 2019. "A Review on the Control of the Mechanical Properties of Ankle Foot Orthosis for Gait Assistance." Actuators 8, no. 1: 10.

Journal article
Published: 11 September 2018 in Biomedical Signal Processing and Control
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In many gait applications, the focal events are the stance and swing phases. Although detecting gait events using electromyography signals will help the development of assistive devices such as exoskeleton, orthoses, and prostheses, stance and swing phases have yet to be observed using electromyography signals. The core of this study is to propose a classification system for both stance and swing phases based on electromyography signals. This is to be done by extracting the patterns of electromyography signals from time domain features and feeding them into an artificial neural network classifier. In addition, a different number of input features and two prominent training algorithm of artificial neural network have been employed in this study. Eight subjects that participated in this study were divided into two categories namely, learned (first seven subjects) and unlearned data (the remaining one subject). It was observed that Levenberg-Marquardt algorithm with five time domain features performed better than other features with an average percentage of classification accuracy of 87.4%. This system was further tested with electromyography signals of learned and unlearned data to identify the stance and swing phases in order to detect the timing of heel strike and toe off. The mean absolute different values between artificial neural network and footswitch data for learned data were 16 ± 18 ms and 21 ± 18 ms for heel strike and toe off, respectively. For this case, no significant differences (p < 0.05) were observed in mean absolute different for heel strike and toe off detections. Besides, the mean absolute different values of unlearned data were shown to be acceptable, 35 ± 25 ms for heel strike and 49 ± 15 ms for toe off. By the end of this experiment, basing the examination of gait events with electromyography signals using artificial neural network is possible.

ACS Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Shin-Ichiroh Yamamoto; Siti Anom Ahmad. Walking gait event detection based on electromyography signals using artificial neural network. Biomedical Signal Processing and Control 2018, 47, 334 -343.

AMA Style

Nurhazimah Nazmi, Mohd Azizi Abdul Rahman, Shin-Ichiroh Yamamoto, Siti Anom Ahmad. Walking gait event detection based on electromyography signals using artificial neural network. Biomedical Signal Processing and Control. 2018; 47 ():334-343.

Chicago/Turabian Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Shin-Ichiroh Yamamoto; Siti Anom Ahmad. 2018. "Walking gait event detection based on electromyography signals using artificial neural network." Biomedical Signal Processing and Control 47, no. : 334-343.

Journal article
Published: 13 October 2017 in Applied Sciences
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In order to analyse surface electromyography (EMG) signals, it is necessary to extract the features based on a time or frequency domain. These approaches are based on the mathematical assumption of signal stationarity. Stationarity of EMG signals is thoroughly examined, especially in isotonic contractions. According to research, conflicting results have been identified depending on varying window sizes. Therefore, in this study, the authors endeavoured to determine the suitable window size to analyse EMG signals during isotonic contractions utilising stationary tests, reverse arrangement (RA), and modified reverse arrangement (MRA). There were slight differences in the average percentages of signal stationarity for RA and MRA tests in 100 ms, 500 ms, and 1000 ms window sizes. However, there was none for the 200 ms window size. On average, a window size of 200 ms provided stationary information with 88.57% of EMG signals compared to other window sizes. This study also recommended the MRA test to determine EMG signals stationarity for future studies, as the performances were better in comparison to RA tests. However, the following recommendation is only valid for window sizes greater than 200 ms. For a real-time application, the size of the analysis window together with the processing time should be less than 300 ms and a window size of 200 ms is applicable for isotonic contractions.

ACS Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Shin-Ichiroh Yamamoto; Siti Anom Ahmad; Mb Malarvili; Saiful Amri Mazlan; Hairi Zamzuri. Assessment on Stationarity of EMG Signals with Different Windows Size During Isotonic Contractions. Applied Sciences 2017, 7, 1050 .

AMA Style

Nurhazimah Nazmi, Mohd Azizi Abdul Rahman, Shin-Ichiroh Yamamoto, Siti Anom Ahmad, Mb Malarvili, Saiful Amri Mazlan, Hairi Zamzuri. Assessment on Stationarity of EMG Signals with Different Windows Size During Isotonic Contractions. Applied Sciences. 2017; 7 (10):1050.

Chicago/Turabian Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Shin-Ichiroh Yamamoto; Siti Anom Ahmad; Mb Malarvili; Saiful Amri Mazlan; Hairi Zamzuri. 2017. "Assessment on Stationarity of EMG Signals with Different Windows Size During Isotonic Contractions." Applied Sciences 7, no. 10: 1050.

Review
Published: 17 August 2016 in Sensors
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In recent years, there has been major interest in the exposure to physical therapy during rehabilitation. Several publications have demonstrated its usefulness in clinical/medical and human machine interface (HMI) applications. An automated system will guide the user to perform the training during rehabilitation independently. Advances in engineering have extended electromyography (EMG) beyond the traditional diagnostic applications to also include applications in diverse areas such as movement analysis. This paper gives an overview of the numerous methods available to recognize motion patterns of EMG signals for both isotonic and isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who would like to select the most appropriate methodology in classifying motion patterns, especially during different types of contractions. For feature extraction, the probability density function (PDF) of EMG signals will be the main interest of this study. Following that, a brief explanation of the different methods for pre-processing, feature extraction and classifying EMG signals will be compared in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.

ACS Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Shin-Ichiroh Yamamoto; Siti Anom Ahmad; Hairi Zamzuri; Saiful Amri Mazlan. A Review of Classification Techniques of EMG Signals during Isotonic and Isometric Contractions. Sensors 2016, 16, 1304 .

AMA Style

Nurhazimah Nazmi, Mohd Azizi Abdul Rahman, Shin-Ichiroh Yamamoto, Siti Anom Ahmad, Hairi Zamzuri, Saiful Amri Mazlan. A Review of Classification Techniques of EMG Signals during Isotonic and Isometric Contractions. Sensors. 2016; 16 (8):1304.

Chicago/Turabian Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Shin-Ichiroh Yamamoto; Siti Anom Ahmad; Hairi Zamzuri; Saiful Amri Mazlan. 2016. "A Review of Classification Techniques of EMG Signals during Isotonic and Isometric Contractions." Sensors 16, no. 8: 1304.

Conference paper
Published: 01 March 2015 in 2015 2nd International Conference on Biomedical Engineering (ICoBE)
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Electromyography (EMG) is an experiment-based method for evaluating and recording a series of electrical signals that emanate from body muscles. The electrical manifestation of neuromuscular activation generated in muscles during contraction and/or relaxation is known as EMG signals. In this paper, a preliminary study is conducted in order to improve the fitness of post-stroke survivors with a minimal supervision from therapists in physiological activity especially on the lower limb rehabilitation. Therefore, a pattern recognition technique is required to extract the important features of an EMG signal to control the physiological devices (PDs), for instance, cycling-like and stepping-like machines in a lower limb rehab application. A new approach for feature extraction vectors in a recognition system will be proposed using Discrete Wavelet Transform (DWT) and Fuzzy C-Means (FCM) algorithms. In addition to this, a Principle Component Analysis (PCA) method will be utilized to reduce the dimension of data in prior to computing the classification accuracy using the Adaptive Neuro-Fuzzy Inference System (ANFIS).

ACS Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Saiful Amri Mazlan; Hairi Zamzuri; Makoto Mizukawa; Nazmi Nurhazimah. Electromyography (EMG) based signal analysis for physiological device application in lower limb rehabilitation. 2015 2nd International Conference on Biomedical Engineering (ICoBE) 2015, 1 -6.

AMA Style

Nurhazimah Nazmi, Mohd Azizi Abdul Rahman, Saiful Amri Mazlan, Hairi Zamzuri, Makoto Mizukawa, Nazmi Nurhazimah. Electromyography (EMG) based signal analysis for physiological device application in lower limb rehabilitation. 2015 2nd International Conference on Biomedical Engineering (ICoBE). 2015; ():1-6.

Chicago/Turabian Style

Nurhazimah Nazmi; Mohd Azizi Abdul Rahman; Saiful Amri Mazlan; Hairi Zamzuri; Makoto Mizukawa; Nazmi Nurhazimah. 2015. "Electromyography (EMG) based signal analysis for physiological device application in lower limb rehabilitation." 2015 2nd International Conference on Biomedical Engineering (ICoBE) , no. : 1-6.