We carried out an experimental study of Mach 2.5 airflow over a semicircular column with 15 kHz arc plasma energy deposition (APED). The APED was pulsed at microsecond time scales, and it rapidly added high-repetition-frequency thermal bubbles that propagated downstream. Time-resolved schlieren imaging with a frame rate of 30 kHz was utilized to record the dynamic flow fields. This study was aimed at investigating the effects of these thermal bubbles on the unsteadiness characterization of a shock wave/turbulent boundary layer interaction (STBLI) by some statistical methods based on the spatial gray value extracted from a sequence of time-resolved schlieren images. The results showed that APED pulsed at 15 kHz was highly effective in weakening both the separation shock and the attached shock continuously and in narrowing the low frequency component of the oscillatory separation shock. A stronger oscillation of the attached shock under APED was found. The thermal bubbles increased the characteristic scales of vortex in the incoming turbulent boundary layer and shear layer, enhancing the fluctuation of the shear layer with large numbers of high-frequency components. The continuous transforming of the enlarged eddies along the shear layer was regarded as the main cause of shock weakening and frequency modulation of the STBLI in this study.
Background
Hypothalamic hamartoma (HH) is a congenital non-progressive lesion of hypothalamus during fetal development. Mass-like lesions in different anatomical locations often develop a variously disabling course presenting with cognitive decline, psychiatric symptoms, as well as multiple seizure types. As a rare disease, HH is relatively common in infants and children, but it is extremely rare in adults.
Case presentation
We reported a case of adult-onset hypothalamic hamartoma, and summarized and analyzed relevant reports and studies of HH worldwide. The patient had clinical manifestations characterized by multiple seizure forms. After stereotactic radiofrequency thermocoagulation and drug treatment, the condition was effectively controlled. The patient was followed up till October 2022, with no recurrence of seizures.
Conclusions
Epilepsy caused by HH can resemble that of temporal lobe seizures, as HH forms a complex epileptogenic network with other regions of the brain through anatomical and functional connections. Early treatment of HH can provide better control of the symptoms of epilepsy, and patients with longer disease courses may have more complications.
This paper presents an investigation into the interaction between a low-speed compressor and a circumferential inlet distortion, through high-resolution measurements and full annulus Detached-Eddy simulation. Experimental results show the compressor behaviors with inlet distortion, and three novel distortion coefficients are presented to build the relationship between the distortion features and the compressor characteristics. Through the unsteady simulation and casing pressure, the rotor stall process with inlet distortion is well captured. Differing from normal ‘spikes’ form, the stall process can be divided into three stages. First, the stall inceptions occur in those blade tips with high blade loads. They can circumferentially propagate several blade passages, but reduce and disappear quickly when they move to low-load blade zone. Then, some of the stall inceptions develop into unsteady stall cells, which can propagate to all the blade passages but may disappear after several cycles. Finally, one of the stall cells becomes stable and the rotor runs into a rotating stall. Comparing experimental and simulation data, Detached-Eddy simulation can provide more details of the stall process than the RANS method. But it is still not precise enough to predict the rotor stall point with inlet distortion.
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