Researcher: Saleem, Muhammad Khurram
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Saleem, Muhammad Khurram
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Publication Metadata only Classification of pharynx from MRI using a visual analysis tool to study obstructive sleep apnea(Bentham Science, 2021) Shahid, Muhammad Laiq Ur Rahman; Mir, Junaid; Shaukat, Furqan; Tariq, Muhammad Atiq Ur Rehman; Nouman, Ahmed; Saleem, Muhammad Khurram; PhD Student; Graduate School of Sciences and Engineering; N/ABackground: Obstructive sleep apnea (OSA) is a chronic sleeping disorder. The analysis of the pharynx and its surrounding tissues can play a vital role in understanding the pathogenesis of OSA. Classification of the pharynx is a crucial step in the analysis of OSA. Methods: A visual analysis-based classifier is developed to classify the pharynx from MRI datasets. The classification pipeline consists of different stages, including pre-processing to select the initial candidates, extraction of categorical and numerical features to form a multidimensional features space, and a supervised classifier trained by using visual analytics and silhouette coefficient to classify the pharynx. Results: The pharynx is classified automatically and gives an approximately 86% Jaccard coefficient by evaluating the classifier on different MRI datasets. The expert's knowledge can be utilized to select the optimal features and their corresponding weights during the training phase of the classifier. Conclusion: The proposed classifier is accurate and more efficient in terms of computational cost. It provides additional insight to better understand the influence of different features individually and collectively. It finds its applications in epidemiological studies where large datasets need to be analyzed.Publication Metadata only Tactile perception of change in friction on an ultrasonically actuated glass surface(Institute of Electrical and Electronics Engineers (IEEE), 2017) Yılmaz, Çetin; N/A; Department of Mechanical Engineering; Saleem, Muhammad Khurram; Başdoğan, Çağatay; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 125489We conducted psychophysical experiments to investigate human haptic perception when they experience a step change in friction on an ultrasonically actuated glass surface under two experimental conditions; sliding finger and stationary finger pressed on the surface. During the experiments, the forces acting on the subjects' finger and the out of plane vibrations of the touch surface were measured by a force and a piezoelectric sensor, respectively. The results showed that stationary finger more easily detected falling friction, whereas, sliding finger was more sensitive to rising friction at higher actuation levels. Moreover, sliding finger was twice more sensitive to changes in friction than stationary finger. Finally, we found that the rate of change of contact forces were best correlated with the subjects' perception of change in friction under both experimental conditions.Publication Metadata only Roughness perception of virtual textures displayed by electrovibration on touch screens(IEEE, 2017) N/A; N/A; N/A; Department of Mechanical Engineering; Vardar, Yasemin; İşleyen, Aykut; Saleem, Muhammad Khurram; Başdoğan, Çağatay; PhD Student; Master Student; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 125489In this study, we have investigated the human roughness perception of periodical textures on an electrostatic display by conducting psychophysical experiments with 10 subjects. To generate virtual textures, we used low frequency unipolar pulse waves in different waveform (sinusoidal, square, saw-tooth, triangle), and spacing. We modulated these waves with a 3kHz high frequency sinusoidal carrier signal to minimize perceptional differences due to the electrical filtering of human finger and eliminate low-frequency distortions. The subjects were asked to rate 40 different macro textures on a Likert scale of 1-7. We also collected the normal and tangential forces acting on the fingers of subjects during the experiment. The results of our user study showed that subjects perceived the square wave as the roughest while they perceived the other waveforms equally rough. The perceived roughness followed an inverted U-shaped curve as a function of groove width, but the peak point shifted to the left compared to the results of the earlier studies. Moreover, we found that the roughness perception of subjects is best correlated with the rate of change of the contact forces rather than themselves.Publication Open Access Psychophysical evaluation of change in friction on an ultrasonically-actuated touchscreen(Institute of Electrical and Electronics Engineers (IEEE), 2018) Yılmaz, Çetin; Department of Mechanical Engineering; Başdoğan, Çağatay; Saleem, Muhammad Khurram; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; 125489; N/ATo render tactile cues on a touchscreen by friction modulation, it is important to understand how humans perceive a change in friction. In this study, we investigate the relations between perceived change in friction on an ultrasonically actuated touchscreen and parameters involved in contact between finger and its surface. We first estimate the perceptual thresholds to detect rising and falling friction while a finger is sliding on the touch surface. Then, we conduct intensity scaling experiments and investigate the effect of finger sliding velocity, normal force, and rise/fall time of vibration amplitude (transition time) on the perceived intensity of change in friction. In order to better understand the role of contact mechanics, we also look into the correlations between the perceived intensities of subjects and several parameters involved in contact. The results of our experiments show that the contrast and rate of change in tangential force were best correlated with the perceived intensity. The subjects perceived rising friction more strongly than falling friction, particularly at higher tangential force contrast. We argue that this is due to hysteresis and viscoelastic behavior of fingertip under tangential loading. The results also showed that transition time and normal force have significant effect on our tactile perception..Publication Open Access Tactile perception of virtual edges and gratings displayed by friction modulation via ultrasonic actuation(Institute of Electrical and Electronics Engineers (IEEE), 2020) Yılmaz, Çetin; Department of Mechanical Engineering; Saleem, Muhammad Khurram; Başdoğan, Çağatay; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 125489Tactile discrimination and roughness perception of real textures are extensively studied and underlying perceptual mechanisms are relatively well-established. However, tactile perception of virtual textures rendered by friction modulation techniques on touch surfaces has not been investigated in detail yet. In this article, we investigated our ability to discriminate two consecutive step changes in friction (called edges), followed by discrimination and roughness perception of multiple edges (called periodic gratings). The results showed that discrimination of two consecutive edges was significantly influenced by edge sequence: a step fall in friction (FF) followed by a step rise in friction (RF) was discriminated more easily than the reverse order. On the other hand, periodic gratings displayed by consecutive sequences of FF followed by RF were perceived with the same acuity as compared to vice versa. Independent of the edge sequence, we found that a relative difference of 14% in spatial period was required to discriminate two periodic gratings. Moreover, the roughness perception of periodic gratings decreased with increasing spatial period for the range that we have investigated (spatial period > 2 mm), despite the lack of spatial cues on grating height. We also observed that rate of change in friction coefficient was better correlated with the roughness perception than the friction coefficient itself. These results will further help to understand and design virtual textures for touch surfaces.