Search

Coronary heart disease (CHD) is currently an important cause of mortality among residents in China and worldwide. The incidence of CHD in China is increasing annually. Among the various factors leading to the occurrence of CHD, abnormalities in blood lipids, especially elevated low-density lipoprotein cholesterol(LDL-C), are particularly significant. Epidemiological, genetic, and clinical studies have confirmed its crucial role in the development of CHD. Therefore, effectively controlling LDL-C levels has become paramount in preventing the onset of CHD and reducing mortality rates. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, as novel lipid-lowering medications, effectively lower LDL-C and play a significant role in preventing major adverse cardiovascular events(MACEs). This article provides a review of PCSK9 inhibitors in clinical treatment related to coronary artery atherosclerosis.

The research explores transition strategies of a coaxial compound helicopter transitioning to pure coaxial-rotor mode following a complete aft propeller failure. For that, a flight dynamics model is developed to predict the transition path, which is formulated as a multiphase trajectory optimization problem. Additionally, a revised aggressiveness indicator is proposed to quantify the transition difficulty. Next, the flight dynamics with and without the propeller and the accelerations at the propeller loss instant are discussed from a trim perspective. Finally, dynamic transitions are meticulously analyzed and compared using a multidimensional radar map to identify an effective strategy. Contrary to the static trim analysis, dynamic simulation results highlight the critical importance of pitch attitude control, longitudinal speed stability, and incidence instability. The potential threats include blade tip collision, significant height increase up to 300 m, and reverse longitudinal stick control regarding pitch attitude. To mitigate these risks and reduce pilot workload, we recommend gradually pitching up to enter the quasi-autorotation state. Additionally, slightly lowering the position of the propeller and maintaining a positive pitch attitude during normal flight can help improve aircraft transition stability. [ABSTRACT FROM AUTHOR]

Sling configurations significantly influence the coupled dynamics of the helicopter with slung load system (HSLS), resulting in alterations to handling qualities (HQs) that remain inadequately understood. This study introduces a computer-oriented, generalized method for constructing the HSLS model with various sling configurations. To evaluate the HQs of 1-point, 2-point, and 4-point sling configurations, both the stability and response criteria outlined in ADS-33E and a newly proposed criterion for slung loads towards the updated ADS-33F were employed. Modal analysis was conducted to elucidate the coupled mechanisms of the HSLS under different sling configurations. The findings reveal that the dynamics of the main rotor can attenuate the lateral swing motions of the load in the 4-point sling configuration. While multiple-point sling configurations can enhance the helicopter's bandwidth, they also amplify the magnitude notch in the helicopter's response. Nevertheless, when a larger hook distance is employed, the notch frequency is sufficiently distant from the load swing bandwidth, leading to a reduced degradation in HQs. A 4-point configuration with lateral and longitudinal hook distances equal to twice the width and length of the slung load is recommended in practice to achieve sufficient swing stability and mitigate HQ degradation. [ABSTRACT FROM AUTHOR]

This paper presents an active flow control of ship airwake over the deck to improve the safety of helicopter shipboard operations in various angles of wind over deck (WOD). Firstly, an integrated flight dynamics method coupled with ship airwake was developed to analyze the effect of ship airwake on the helicopter at various angles of WOD. Then, an active flow control strategy in various angles of WOD was investigated with the analysis of airwake distribution and the impact on helicopter trim flight. Finally, the effects of active blowing on airwake distribution, flight control inputs, control margins, and helicopter attitudes in trim were analyzed. The results indicate that the variation of the angles of WOD has a significant impact on flight controls and helicopter attitudes for helicopter hovering relative to ship motion. The nonuniformity of ship airwake can be effectively alleviated by applying active flow control. The variations of flight control inputs and helicopter attitude angles at trim states are reduced, which increases the control margins and contributes to enhancing the safety of helicopter shipboard operations. [ABSTRACT FROM AUTHOR]

This study assesses the influence of engine dynamic characteristics on helicopter handling quality during hover and low-speed forward flight. First, we construct the helicopter–engine coupling model (HECM) based on the power-matching relationship between the engine and the rotor. The impact of the engine is evaluated by comparing HECM with a helicopter model without the engine. To assess the engine's influence quantitatively, we consider torque response, height response, and collective–yaw coupling characteristics in ADS-33E-PRF handling quality criteria. The results reveal that the engine power output lag can deteriorate the helicopter's torque and height response handling quality rate (HQR). After the increase in helicopter mass, the torque HQR caused by engine influence improved, and the altitude HQR further deteriorated. The engine dynamic characteristics can also reverse the yaw rate, decreasing collective–yaw coupling HQR. As the helicopter's flight speed increased, the engine's impact on the yaw rate increased by 41.8%. This study can provide valuable insight into the effects of engine dynamic characteristics on helicopter handling quality and offer a reference for the design of helicopter–engine coupling control laws. [ABSTRACT FROM AUTHOR]

The ducted coaxial propeller (DCP) has great application value in eVTOL aircraft because of its high safety, compactness, and low noise. A numerical simulation method for the DCP is established using the sliding mesh technique. A DCP was designed and manufactured for the lift and power test to verify the numerical method. The characteristics of airflow separation inside the DCP were studied, and the influence of the vortex restrain ring (VRR) on the suppression of airflow separation and on lift augmentation of the duct is analyzed. Results show that, when the tip clearance ratio increases from 0.336% to 1.342%, both the total lift and aerodynamic efficiency decrease by about 11.3%. The influence is mainly reflected in the formation of the tip vortex, airflow separation in the straight, and diffusion sections of the duct. Tip vortex and airflow separation increases DCP energy dissipation and clogs the inner wall of the duct, reducing the effective inner diameter and airflow through the duct. Moreover, the role of the duct is weakened, and the wake is contracted, which increases the induced power loss. By adding a VRR to the diffusion section, the tip vortex and airflow separation can be effectively suppressed, which can increase the aerodynamic efficiency by 5.1%. [ABSTRACT FROM AUTHOR]