Publications by authors named "Adnan Yousaf"

7 Publications

  • Page 1 of 1

Simultaneous Power Feedback and Maximum Efficiency Point Tracking for Miniaturized RF Wireless Power Transfer Systems.

Sensors (Basel) 2021 Mar 12;21(6). Epub 2021 Mar 12.

Laboratory for Electrical Instrumentation and Embedded Systems, Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany.

Near-field interfaces with miniaturized coil systems and low output power levels, such as applied in biomedical sensor systems, can suffer from severe efficiency degradation due to dynamic impedance mismatches, reducing battery life of the power transmitter unit and requiring to increase the level of electromagnetic emission. Moreover, the stability of weakly-coupled power transfer systems is generally limited by transient changes in coil alignment and load power consumption. Hence, a central research question in the domain of wireless power transfer is how to realize an adaptive impedance matching system under the constraints of a simultaneous power feedback to increase the system's efficiency and stability, while maintaining circuit characteristics such as small size, low power consumption and fast reaction times. This paper presents a novel approach based on a two-stage control loop implemented in the primary-side reader unit, which uses a digital PI controller to maintain the rectifier output voltage for power feedback and an on-top perturb-and-observe controller configuring the setpoint of the voltage controller to maximize efficiency. The paper mathematically analyzes the AC and DC transfer characteristics of a resonant inductive link to design the reactive AC matching network, the digital voltage controller and ultimately the DC-domain impedance matching algorithm. It was found that static reactive L networks result in suitable efficiency levels for coils with sufficiently high quality factor even without adaptive tuning of operational frequency or reactive components. Furthermore, the regulated output voltage of the rectifier is a direct measure of the DC load impedance when using a regular DC/DC converter to supply the load circuits, so that this quantity can be tuned to maximize efficiency. A prototype implementation demonstrates the algorithms in a 40.68 MHz inductive link with load power levels from 10 to 100 mW and tuning time constants of 300 ms, while allowing for a simplified receiver with a footprint smaller than 200 mm and a self-consumption below 1 mW. Hence, the presented concepts enable adaptive impedance matching with favorable characteristics for low-energy sensor systems, i.e., minimized footprint, power level and reaction time.
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http://dx.doi.org/10.3390/s21062023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8000423PMC
March 2021

Exploring the Relationship between Attitudes, Risk Perceptions, Fatalistic Beliefs, and Pedestrian Behaviors in China.

Int J Environ Res Public Health 2021 03 24;18(7). Epub 2021 Mar 24.

Human Factors Engineering, Transportation Research Group, University of Southampton, Southampton SO16 7QF, UK.

Road safety has become a worldwide public health concern. Although many factors contribute to collisions, pedestrian behaviors can strongly influence road safety outcomes. This paper presents results of a survey investigating the effects of age, gender, attitudes towards road safety, fatalistic beliefs and risk perceptions on self-reported pedestrian behaviors in a Chinese example. The study was carried out on 543 participants (229 men and 314 women) from 20 provinces across China. Pedestrian behaviors were assessed by four factors: errors, violations, aggressions, and lapses. Younger people reported performing riskier pedestrian behaviors compared to older people. Gender was not an influential factor. Of the factors explored, attitudes towards road safety explained the most amount of variance in self-reported behaviors. Significant additional variance in risky pedestrian behaviors was explained by the addition of fatalistic beliefs. The differences among the effects, and the implications for road safety intervention design, are discussed. In particular, traffic managers can provide road safety education and related training activities to influence pedestrian behaviors positively.
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http://dx.doi.org/10.3390/ijerph18073378DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8037076PMC
March 2021

Very High Bit Rate Near-Field Communication with Low-Interference Coils and Digital Single-Bit Sampling Transceivers for Biomedical Sensor Systems.

Sensors (Basel) 2020 Oct 23;20(21). Epub 2020 Oct 23.

Laboratory for Electrical Instrumentation, Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany.

The evolution of microelectronics increased the information acquired by today's biomedical sensor systems to an extent where the capacity of low-power communication interfaces becomes one of the central bottlenecks. Hence, this paper mathematically analyzes and experimentally verifies novel coil and transceiver topologies for near-field communication interfaces, which simultaneously allow for high data transfer rates, low power consumption, and reduced interference to nearby wireless power transfer interfaces. Data coil design is focused on presenting two particular topologies which provide sufficient coupling between a reader and a wireless sensor system, but do not couple to an energy coil situated on the same substrate, severely reducing interference between wireless data and energy transfer interfaces. A novel transceiver design combines the approaches of a minimalistic analog front-end with a fully digital single-bit sampling demodulator, in which rectangular binary signals are processed by simple digital circuits instead of sinusoidal signals being conditioned by complex analog mixers and subsequent multi-bit analog-to-digital converters. The concepts are implemented using an analog interface in discrete circuit technology and a commercial low-power field-programmable gate array, yielding a transceiver which supports data rates of up to 6.78 MBit/s with an energy consumption of just 646 pJ/bit in transmitting mode and of 364 pJ/bit in receiving mode at a bit error rate of 2×10-7, being 10 times more energy efficient than any commercial NFC interface and fully implementable without any custom CMOS technology.
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http://dx.doi.org/10.3390/s20216025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660340PMC
October 2020

A genome-wide analysis in consanguineous families reveals new chromosomal loci in specific language impairment (SLI).

Eur J Hum Genet 2019 08 11;27(8):1274-1285. Epub 2019 Apr 11.

Child Language Doctoral Program (CLDP), University of Kansas, Lawrence, KS, USA.

Language is a uniquely human ability, and failure to attain this ability can have a life-long impact on the affected individuals. This is particularly true for individuals with specific language impairment (SLI), which is defined as an impairment in normal language development in the absence of any other developmental disability. Although SLI displays high heritability, family-based linkage studies have been hampered by an unclear mode of Mendelian segregation, variable disease penetrance, and heterogeneity of diagnostic criteria. We performed genome-wide parametric linkage analysis and homozygosity mapping in 14 consanguineous families from Pakistan segregating SLI. Linkage analysis revealed a multipoint LOD score of 4.18 at chromosome 2q in family PKSLI05 under a recessive mode of inheritance. A second linkage score of 3.85 was observed in family PKSLI12 at a non-overlapping locus on chromosome 2q. Two other suggestive linkage loci were found in family PKSLI05 on 14q and 22q with LOD scores of 2.37 and 2.23, respectively, that were also identified in homozygosity mapping. Reduction to homozygosity was observed on chromosomes 2q, 5p, 8q, 14q, 17q, and 22q. Each homozygosity region occurred in multiple PKSLI families. We report new SLI loci on chromosomes 2 and 8 and confirm suggestive SLI linkage loci on chromosomes 5, 14, 17, and 22 reported previously in the population of Robinson Crusoe Island. These findings indicate that linkage and homozygosity mapping in consanguineous families can improve genetic analyses in SLI and suggest the involvement of additional genes in the causation of this disorder.
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http://dx.doi.org/10.1038/s41431-019-0398-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777459PMC
August 2019

A 'false' pin-hole occurring after late-presenting myocardial infarction.

Eur Heart J Cardiovasc Imaging 2017 07;18(7):818

Cardiology Department, Morriston Hospital, SA6 6NL, Swansea, UK.

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http://dx.doi.org/10.1093/ehjci/jex039DOI Listing
July 2017

Acute Appendicitis Complicating into Portal and Superior Mesenteric Vein Thrombosis.

J Coll Physicians Surg Pak 2016 06;26(6 Suppl):S10-2

Department of Surgery, Ward A, Khyber Teaching Hospital, Peshawar.

This case report describes a young man who presented with 9-day history of sudden-onset epigastric and right-sided lower abdominal pain. He was tachycardiac with temperature of 102°F. Tenderness was present in the peri-umbilical area and right iliac fossa. Investigations revealed a raised total leucocyte count (predominantly neutrophilic). Triphasic CTscan abdomen found thrombosis of right portal vein and its hepatic tributaries alongwith superior mesenteric vein (SMV) and its tributaries. Co-existent fluid in right hemipelvis abutting the cecum and appendiceal tip was suggestive of acute appendicitis. He was resuscitated with fluids and analgesics and started on intravenous metronidazole and ceftriaxone. Anticoagulation with subcutaneous heparin was commenced and eventually switched over to warfarin. Appendicectomy was not performed as the patient responded to conservative treatment. Appendicitis is associated with multiple complications but secondary venous thrombosis has rarely been reported with it.
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June 2016

Differences in detection rates for serious neonatal diseases before and after institution of newborn rounds by paediatricians in a private sector hospital.

J Ayub Med Coll Abbottabad 2010 Jan-Mar;22(1):143-6

Department of Paediatrics, Peshawar Medical College, Peshawar, Pakistan.

Background: Perinatal and infant mortality are two major contributors to child mortality in developing world. It is widely recognised that synergistic efforts by paediatric and obstetric healthcare providers result in improvement of neonatal and infant survival. Close working relationship between the 2 disciplines with attendance of all high risk births by paediatric healthcare providers and routine examination of all neonates is required for this purpose. Objectives were to compare 2 continuums of 100 neonatal cases for detection of serious neonatal disease. One set of neonates being examined by neonatal/paediatric service and other without this service in place.

Methods: One hundred Neonatal Exam sheets were selected randomly from records of 2007-2008 and compared with 100 Neonatal Exam Sheets of 2006-2007. Records were analysed for detection of serious neonatal conditions at 24 hours age. Data was analysed using MS EXCEL. Odds ratio was calculated for each disease with Haldane correction.

Results: Odds ratio was significantly higher for detection of serious neonatal diseases in 2007-2008 group when neonatal service was actively involved in newborn examinations of all neonates. Highest odds ratios were obtained for detection of Heart Murmur and neonatal sepsis.

Conclusions: Newborn Examination within 24-48 hours of birth by trained neonatal healthcare provider is paramount for adequate detection of serious neonatal diseases. Such services should be instituted in all obstetric units for better neonatal outcome.
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April 2011