ORCID Profile
0000-0003-1517-185X
Current Organisations
Centre for Addiction and Mental Health
,
University of Toronto
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Publisher: MDPI AG
Date: 06-01-2022
DOI: 10.3390/S22020424
Abstract: For low input radio frequency (RF) power from −35 to 5 dBm, a novel quad-band RF energy harvester (RFEH) with an improved impedance matching network (IMN) is proposed to overcome the poor conversion efficiency and limited RF power range of the ambient environment. In this research, an RF spectral survey was performed in the semi-urban region of Malaysia, and using these results, a multi-frequency highly sensitive RF energy harvester was designed to harvest energy from available frequency bands within the 0.8 GHz to 2.6 GHz frequency range. Firstly, a new IMN is implemented to improve the rectifying circuit’s efficiency in ambient conditions. Secondly, a self-complementary log-periodic higher bandwidth antenna is proposed. Finally, the design and manufacture of the proposed RF harvester’s prototype are carried out and tested to realize its output in the desired frequency bands. For an accumulative −15 dBm input RF power that is uniformly universal across the four radio frequency bands, the harvester’s calculated dc rectification efficiency is about 35 percent and reaches 52 percent at −20 dBm. Measurement in an ambient RF setting shows that the proposed harvester is able to harvest dc energy at −20 dBm up to 0.678 V.
Publisher: SAGE Publications
Date: 18-11-2022
DOI: 10.1177/07067437211055414
Abstract: In iduals with mental illness and addiction are overrepresented in prisons. Few studies have assessed mental health and addiction (MHA)-related service use among in iduals experiencing incarceration using health administrative data and most focus on service use after prison release. The objective of this study was to determine the prevalence of MHA-related service use in the 5 years prior to and during incarceration. We used linked correctional and administrative health data for people released from Ontario provincial jails in 2010. MHA-related service use in the 5 years prior to the index incarceration was categorized hierarchically into four mutually exclusive categories based on the type of service use: psychiatric hospitalization, MHA-related emergency department (ED) visit, MHA-related outpatient visit (from psychiatrist or primary care physician), and no MHA-related service use. Demographic, diagnostic, and incarceration characteristics were compared across the four service use categories. MHA-related service use during the index incarceration was assessed by category and length of incarceration. A total of 48,917 in iduals were included. Prior to incarceration, 6,116 (12.5%) had a psychiatric hospitalization, 8,837 (18.1%) had an MHA-related ED visit, and 15,866 (32.4%) had an MHA-related outpatient visit. Of the in iduals with any MHA-related service prior to incarceration, 60.4% did not receive outpatient care from a psychiatrist prior to incarceration and 65.6% did not receive MHA-related care during incarceration. Despite a high prevalence of mental illness and addiction among people experiencing incarceration, access to and use of MHA-related care prior to and during incarceration is poor. Increasing the accessibility and use of MHA-related services throughout the criminal justice pathway is warranted.
Publisher: MDPI AG
Date: 25-11-2021
DOI: 10.3390/S21237838
Abstract: RF power is broadly available in both urban and semi-urban areas and thus exhibits as a promising candidate for ambient energy scavenging sources. In this research, a high-efficiency quad-band rectenna is designed for ambient RF wireless energy scavenging over the frequency range from 0.8 to 2.5 GHz. Firstly, the detailed characteristics (i.e., available frequency bands and associated power density levels) of the ambient RF power are studied and analyzed. The data (i.e., RF survey results) are then applied to aid the design of a new quad-band RF harvester. A newly designed impedance matching network (IMN) with an additional L-network in a third-branch of dual-port rectifier circuit is familiarized to increase the performance and RF-to-DC conversion efficiency of the harvester with comparatively very low input RF power density levels. A dual-polarized multi-frequency bow-tie antenna is designed, which has a wide bandwidth (BW) and is miniature in size. The dual cross planer structure internal triangular shape and co-axial feeding are used to decrease the size and enhance the antenna performance. Consequently, the suggested RF harvester is designed to cover all available frequency bands, including part of most mobile phone and wireless local area network (WLAN) bands in Malaysia, while the optimum resistance value for maximum dc rectification efficiency (up to 48%) is from 1 to 10 kΩ. The measurement result in the ambient environment (i.e., both indoor and outdoor) depicts that the new harvester is able to harvest dc voltage of 124.3 and 191.0 mV, respectively, which can be used for low power sensors and wireless applications.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: IEEE
Date: 07-2018
No related grants have been discovered for Sunanda Roy.