@article{abdelkhalek_baron_wong_2022, title={Mismatched Estimation in the Distance Geometry Problem}, ISSN={["1058-6393"]}, DOI={10.1109/IEEECONF56349.2022.10051876}, abstractNote={We investigate mismatched estimation in the context of the distance geometry problem (DGP). In the DGP, for a set of points, we are given noisy measurements of pairwise distances between the points, and our objective is to determine the geometric locations of the points. A common approach to deal with noisy measurements of pairwise distances is to compute least-squares estimates of the locations of the points. However, these least-squares estimates are likely to be suboptimal, because they do not necessarily maximize the correct likelihood function. In this paper, we argue that more accurate estimates can be obtained when an estimation procedure that uses the correct likelihood function of noisy measurements is performed. Our numerical results demonstrate that least-squares estimates can be suboptimal by several dB.}, journal={2022 56TH ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS, AND COMPUTERS}, author={Abdelkhalek, Mahmoud and Baron, Dror and Wong, Chau-Wai}, year={2022}, pages={1031–1035} }
 @article{abdelkhalek_qiu_hernandez_bozkurt_lobaton_2021, title={Investigating the Relationship between Cough Detection and Sampling Frequency for Wearable Devices}, ISSN={["1558-4615"]}, url={http://dx.doi.org/10.1109/embc46164.2021.9630082}, DOI={10.1109/EMBC46164.2021.9630082}, abstractNote={Cough detection can provide an important marker to monitor chronic respiratory conditions. However, manual techniques which require human expertise to count coughs are both expensive and time-consuming. Recent Automatic Cough Detection Algorithms (ACDAs) have shown promise to meet clinical monitoring requirements, but only in recent years they have made their way to non-clinical settings due to the required portability of sensing technologies and the extended duration of data recording. More precisely, these ACDAs operate at high sampling frequencies, which leads to high power consumption and computing requirements, making these difficult to implement on a wearable device. Additionally, reproducibility of their performance is essential. Unfortunately, as the majority of ACDAs were developed using private clinical data, it is difficult to reproduce their results. We, hereby, present an ACDA that meets clinical monitoring requirements and reliably operates at a low sampling frequency. This ACDA is implemented using a convolutional neural network (CNN), and publicly available data. It achieves a sensitivity of 92.7%, a specificity of 92.3%, and an accuracy of 92.5% using a sampling frequency of just 750 Hz. We also show that a low sampling frequency allows us to preserve patients’ privacy by obfuscating their speech, and we analyze the trade-off between speech obfuscation for privacy and cough detection accuracy.Clinical relevance—This paper presents a new cough detection technique and preliminary analysis on the trade-off between detection accuracy and obfuscation of speech for privacy. These findings indicate that, using a publicly available dataset, we can sample signals at 750 Hz while still maintaining a sensitivity above 90%, suggested to be sufficient for clinical monitoring [1].}, journal={2021 43RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY (EMBC)}, publisher={IEEE}, author={Abdelkhalek, Mahmoud and Qiu, Jinyi and Hernandez, Michelle and Bozkurt, Alper and Lobaton, Edgar}, year={2021}, pages={7103–7107} }
 @article{mohammadi_abdelkhalek_sadrafshari_2020, title={Resonance frequency selective electromagnetic actuation for high-resolution vibrotactile displays}, volume={302}, ISSN={["0924-4247"]}, DOI={10.1016/j.sna.2019.111818}, abstractNote={Vibrotactile displays offer significant potential for conveying information through the sense of touch in a wide variety of applications. Spatial resolution of these displays is limited by the large size of actuators. We present a new selective electromagnetic actuation technique to control the vibrations of multiple tactile elements using a single coil based on their individual mechanical resonance frequencies. This technique allows low-cost and highly reliable implementation of many tactile elements on a smaller area. A prototype is manufactured using 3D-printed tactile elements and off-the-shelf coils to characterize the proposed technique. This prototype successfully increases the resolution by 100 % from 16 to 32 tactile pixels (taxels) on a 25 cm2 pad, without sacrificing other performance metrics such as refresh rates and power consumption. The multiphysics finite element analysis developed for this new actuation technique are experimentally validated by optical vibrometry measurements. This work demonstrates the capability of resonance-selective electromagnetic actuator in developing high-resolution low-cost vibrotactile displays.}, journal={SENSORS AND ACTUATORS A-PHYSICAL}, author={Mohammadi, Ali and Abdelkhalek, Mahmoud and Sadrafshari, Shamin}, year={2020}, month={Feb} }