Development of a Hybrid-Electric Aircraft Propulsion System Based on Silicon Carbide Triple Active Bridge Multiport Power Converter

Constrained by the low energy density of Lithium-ion batteries with all-electric aircraft propulsion, hybrid-electric aircraft propulsion drive becomes one of the most promising technologies in aviation electrification, especially for wide-body airplanes. In this thesis, a three-port triple active bridge (TAB) DC-DC converter is developed to manage the power flow between the turbo generator, battery, and the propulsion motor. The TAB converter is modeled based on the emerging Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) modules operating at high switching frequency, so the size of the magnetic transformer can be significantly reduced. Different operation modes of this hybrid-electric propulsion drive based on the SiC TAB converter are modeled and simulated to replicate the takeoff mode, cruising mode, and regenerative charging mode of a typical flight profile. Additionally, soft switching is investigated for the TAB converter to further improve the efficiency and power density of the converter, and zero voltage switching is achieved at heavy load operating conditions. The results show that the proposed TAB converter is capable of achieving high efficiency during all stages of the flight profile

Successful ACL reconstruction with a variant of the pes anserinus

An anatomical variant of the pes anserinus encountered during anterior cruciate ligament reconstructive surgery which has not been previously described is discussed. During routine harvesting, the sartorius fascia was incised and the semitendinosus and gracilis tendons were identified. At the distal portion, it was noted that each tendon gave off an additional tendinous slip. The slip from the semitendinosus tendon had attached to the gracilis tendon and vice versa, thereby creating a double pes anserinus. This variant was used to construct the graft, and at 1 year review the patient had returned to full sporting activities with no complications encountered

Aerosol delivery to ventilated newborn infants: historical challenges and new directions

There are several aerosolized drugs which have been used in the treatment of neonatal respiratory illnesses, such as bronchodilators, diuretics, and surfactants. Preclinical in vitro and in vivo studies identified a number of variables that affect aerosol efficiency, including particle size, aerosol flows, nebulizer choice, and placement. Nevertheless, an optimized aerosol drug delivery system for mechanically ventilated infants still does not exist. Increasing interest in this form of drug delivery requires more controlled and focused research of drug/device combinations appropriate for the neonatal population. In the present article, we review the research that has been conducted thus far and discuss the next steps in developing the optimal aerosol delivery system for use in mechanically ventilated neonates

The Public Health Impact of Coccidioidomycosis in Arizona and California

The numbers of reported cases of coccidioidomycosis in Arizona and California have risen dramatically over the past decade, with a 97.8% and 91.1% increase in incidence rates from 2001 to 2006 in the two states, respectively. Of those cases with reported race/ethnicity information, Black/African Americans in Arizona and Hispanics and African/Americans in California experienced a disproportionately higher frequency of disease compared to other racial/ethnic groups. Lack of early diagnosis continues to be a problem, particularly in suspect community-acquired pneumonia, underscoring the need for more rapid and sensitive tests. Similarly, the inability of currently available therapeutics to reduce the duration and morbidity of this disease underscores the need for improved therapeutics and a preventive vaccine