The development and application of permanent-magnet EDS based on Halbach structure
With the permanent-magnet EDS (Electro-dynamic Suspension) system as the background, rectilineal PM Halbach structure is introduced. The theory and stability of permanent-magnet EDS system are analyzed which concludes that permanent-magnet EDS system is of greater advantage under high speed condition. Then two present projects based on the the permanent-magnet EDS which aim at actual application, the GA urban maglev train and the Inductrack rocket launch assist system in US, are introduced in details. Adopting double layers PM halbach structure#GA urban maglev train solves the shortage that the levitation-drag ratio is smaller in low speed condition. The Inductrack rocket launch assist system can save fuel and send more payloads. Finally, Permanent EDS research development status home is generalized.
General Atomics Urban Maglev Technology Development
Key technical aspects of the General Atomics (GA) Urban Maglev project are reported. The selected technology is based on the principle of electro-dynamic suspension (EDS) for levitation and a linear synchronous motor (LSM) for propulsion. High field permanent magnets (PM) arranged into Halbach arrays are used on the vehicle for levitation, guidance and propulsion. The Urban Maglev program is sponsored by the Federal Transit Administration (FTA) and directed toward development of maglev technology for urban mass transportation in the United States.
Clinical and echocardiographic characteristics of cardiac blood cysts.
BACKGROUND
Cardiac blood cysts (BCs) are rare benign cardiac masses. This study aimed to summarize the clinical and echocardiographic characteristics and clinical outcomes of patients with BCs.


METHODS
This retrospective study enrolled patients diagnosed with BC between 2009 and 2021 at a single center in China. Their clinical and echocardiographic characteristics, management, and outcomes at follow-up are summarized.


RESULTS
The study population comprised 26 patients with BCs with a mean age of 40 ± 19 years (median, 42 years; range, 27-56 years). The cohort was predominantly male (16, 62%). Twenty-two (81%) patients were symptomatic: dyspnea or exertional dyspnea (11, 42%) and palpitations (6, 23%) were the most frequent symptoms. Most cysts appeared as single round, oval, or lobulated anechoic masses, measuring 4-30 mm (mean, 18 mm). Half of the BCs (13, 50%) were pedunculated and mobile, and the others swung with the movement of the valve. The mitral valve (13, 50%) was the most common site of occurrence, followed by the tricuspid valve (6, 23%), right atrium (4, 15%), and aortic valve (3, 12%). Contrast echocardiography, which was performed for two patients, revealed a closed cyst without bubbles. Five cases were complicated by left ventricular outflow tract obstruction and six by valve prolapse. Eighteen patients underwent surgery, and one received antiplatelet therapy. Cardiovascular or cerebrovascular events did not occur in any patient during the follow-up period.


CONCLUSION
Cardiac BCs are most commonly attached to the atrioventricular valve. Echocardiography is considered to be the most useful imaging modality for assessing BC. The management of patients with BC should be individualized based on the symptoms and associated complications.