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In a boundary layer ingestion (BLI) propulsion system, the compressor rotor operates under the condition of a severe inflow distortion because the boundary layers on the surface of aircraft have been ingested. In this situation, the low-momentum fluid would inevitably raise the blade load and aggravate the local aerodynamic losses, thus severely deteriorating the compressor overall aerodynamic performance. The paper has applied a sweep optimization design based on surrogate model and genetic algorithm to a transonic axial-flow compressor at the condition of total pressure distorted inflow. The optimization objective is to improve the compressor efficiency. The sweep design has been implemented through controlling the shape of the blade stacking line and the time-saving steady numerical simulations are mainly utilized in the optimization process. Then, the full-annulus unsteady CFD calculations have been conducted for validating the optimized design and further analyzing the flow mechanisms of performance improvements. The computational results show that the inflow distortion has led to non-uniform distributions of the tip leakage loss and the hub flow separation loss along the circumferential direction. It is found that the rotor blade has suffered from the highest tip leakage losses and hub separation losses during the blade leaving the distorted region. After rotor sweep optimization, both tip leakage and hub separation losses have been notably reduced along the full circumferential direction. Moreover, for different pitchwise locations, the optimized rotor sweep design has achieved more aerodynamic performance improvements in the process of the rotor blade leaving the distorted region than those in the processes of the rotor blade moving out of, moving towards and entering the distorted region. Overall, the optimized design performs better than the baseline design in terms of adiabatic efficiency in the entire operating range. In the meanwhile, the total pressure ratio has been maintained. Specifically, an approximately 0.5% increment of efficiency has been achieved by the optimized design at the optimization point. For this paper, the major purpose is to offer useful guidelines for fan/compressor design strategy to achieve high aerodynamic performances under distorted inflow working condition.

BackgroundLong-term alcohol drinking is associated with numerous health complications including susceptibility to infection, cancer, and organ damage. However, due to the complex nature of human drinking behavior, it has been challenging to identify reliable biomarkers of alcohol drinking behavior prior to signs of overt organ damage. Recently, extracellular vesicle-bound microRNAs (EV-miRNAs) have been found to be consistent biomarkers of conditions that include cancer and liver disease.MethodsIn this study, we profiled the plasma EV-miRNA content by miRNA-Seq from 80 nonhuman primates after 12 months of voluntary alcohol drinking.ResultsWe identified a list of up- and downregulated EV-miRNA candidate biomarkers of heavy drinking and those positively correlated with ethanol dose. We overexpressed these candidate miRNAs in control primary peripheral immune cells to assess their potential functional mechanisms. We found that overexpression of miR-155, miR-154, miR-34c, miR-450a, and miR-204 led to increased production of the inflammatory cytokines TNFα or IL-6 in peripheral blood mononuclear cells after stimulation.ConclusionThis exploratory study identified several EV-miRNAs that could serve as biomarkers of long-term alcohol drinking and provide a mechanism to explain alcohol-induced peripheral inflammation.

Recognition of overlapping objects is required in many applications in the field of computer vision. Examples include cell segmentation, bubble detection and bloodstain pattern analysis. This paper presents a method to identify overlapping objects by approximating them with ellipses. The method is intended to be applied to complex-shaped regions which are believed to be composed of one or more overlapping objects. The method has two primary steps. First, a pool of candidate ellipses are generated by applying the Euclidean distance transform on a compressed image and the pool is filtered by an overlaying method. Second, the concave points on the contour of the region of interest are extracted by polygon approximation to divide the contour into segments. Then, the optimal ellipses are selected from among the candidates by choosing a minimal subset that best fits the identified segments. We propose the use of the adjusted Rand index, commonly applied in clustering, to compare the fitting result with ground truth. Through a set of computational and optimization efficiencies, we are able to apply our approach in complex images comprised of a number of overlapped regions. Experimental results on a synthetic data set, two types of cell images and bloodstain patterns show superior accuracy and flexibility of our method in ellipse recognition, relative to other methods.

We propose a Bayesian nonparametric clustering approach to study the spatial heterogeneity effect for functional data observed at spatially correlated locations. We consider a geographically weighted Chinese restaurant process equipped with a conditional autoregressive prior to capture fully the spatial correlation of function curves. To sample efficiently from our model, we customize a prior called Quadratic Gamma, which ensures conjugacy. We design a Markov chain Monte Carlo algorithm to infer simultaneously the posterior distributions of the number of groups and the grouping configurations. The superior numerical performance of the proposed method over competing methods is demonstrated using simulated examples and a U.S. annual precipitation study. [ABSTRACT FROM AUTHOR]

This study reveals the blockage effects on vortex shedding, the lock-in mechanism of a forced oscillating cylinder, and the coupling effects of blockage and oscillation. The wind tunnel experiments and large eddy simulations were conducted at a Reynolds number of 2000, encompassing a range of blockage ratios from 0.15 to 0.5. The cylinder is subjected to forced harmonic oscillations in a direction perpendicular to the incoming flow to investigate the frequency lock-in mechanism. The research findings demonstrate that both blockage and forced vibration significantly influence the dynamics of vortex shedding by altering the development of the shear layer instability (SLI). For a fixed cylinder, high blockage effectively suppresses the growth of transverse disturbances, promoting a stable maintenance of the shear layer (SL). In high blockage, the flow deceleration induces the separation of the boundary layer from the sidewalls and the subsequent constriction of the mainstream toward the channel centerline, consequently leading to an increase in the Strouhal number. For the case of a fixed blockage ratio, forced vibration alters the flow supplement in the near-SL region. During the unlocked phase, a significant occurrence of backflow is observed near the SL, which promotes the development of SLI. However, proper vibration induces the transverse flow supplement in the near-SL region, which balance the amount carried away by mainstream, thereby suppressing the backflow. The coupling effects of blockage and vibration are evident in the shift of the lock-in region and the triggering of hysteresis, both of which are explained by the proposed mechanisms of blockage and lock-in. [ABSTRACT FROM AUTHOR]