Maximum Wind Power Tracking of Doubly Fed Wind Turbine System Based on Adaptive Gain Second-Order Sliding Mode

This paper proposes an adaptive gain second-order sliding mode control strategy to track optimal electromagnetic torque and regulate reactive power of doubly fed wind turbine system. Firstly, wind turbine aerodynamic characteristics and doubly fed induction generator (DFIG) modeling are presented. Then, electromagnetic torque error and reactive power error are chosen as sliding variables, and fixed gain super-twisting sliding mode control scheme is designed. Considering that uncertainty upper bound is unknown and is hard to be estimated in actual doubly fed wind turbine system, a gain scheduled law is proposed to compel control parameters variation according to uncertainty upper bound real-time. Adaptive gain second-order sliding mode rotor voltage control method is constructed in detail and finite time stability of doubly fed wind turbine control system is strictly proved. The superiority and robustness of the proposed control scheme are finally evaluated on a 1.5 MW DFIG wind turbine system

CONUT score is associated with short-term prognosis in patients with severe acute pancreatitis: a propensity score matching cohort study

BackgroundThe Controlling Nutritional Status (CONUT) score was designed to assess the immune-nutritional status in patients. This study aimed to investigate the role of the CONUT score in the short-term prognosis of severe acute pancreatitis.MethodsThis was a retrospective cohort study. 488 patients with severe acute pancreatitis at the Department of Critical Care Medicine of the West China Hospital of Sichuan University (Chengdu, China) were enrolled in the study. Baseline data were collected from the West China Hospital of Sichuan University database. The primary outcome during follow-up was all-cause mortality. The secondary outcomes were 28 day mortality, renal insufficiency, length of stay (LOS) in the ICU, and length of stay (LOS) in the hospital. Patients were divided into two groups based on a median CONUT score of 7, and baseline differences between the two groups were eliminated by propensity matching. Univariate Cox regression analyses were performed to estimate the association between CONUT score and outcomes. The Kaplan–Meier method was used to estimate the survival rate of patients.ResultsCONUT score was an independent predictor of all-cause mortality (hazard ratio [HR]:2.093; 95%CI: 1.342–3.263; p < 0.001) and 28 day mortality (hazard ratio [HR]:1.813; 95%CI: 1.135–2.896; p < 0.013). CONUT score was not statistically significant in predicting the incidence of renal insufficiency. The high CONUT group had significantly higher all-cause mortality (p < 0.001), and 28 day mortality (p < 0.011) than the low CONUT group.ConclusionThe CONUT score is an independent predictor of short-term prognosis in patients with severe acute pancreatitis, and timely nutritional support is required to reduce mortality in patients with severe acute pancreatitis

Target tracking control of a bionic mantis shrimp robot with closed-loop central pattern generators

To address the challenge of efficient underwater target tracking, this study focuses on the mantis shrimp as a biomimetic model. The research involves the design of a bionic mantis shrimp robot featuring a structure that supports multi-pleopod coupled movement. We propose a target tracking control system based on a bionic closed-loop central pattern generator (CPG). This system integrates CPG control, proportional integral derivative control, and fuzzy logic control. It aims to enable precise target tracking by dynamically adjusting the robot's motion in response to data from vision sensors. Extensive underwater experiments validate the effectiveness of this control system in both static and dynamic target tracking scenarios. The experiments demonstrate that the bionic mantis shrimp robot can perform multiangle turns and adjust its velocity flexibly in a confined space measuring 2 m × 1 m × 1 m. Notably, the robot can track targets at angles up to 130° relative to its initial motion direction. The minimum tracking turning radius achieved is 0.65 m, highlighting the potential for advanced target tracking and broader applications in underwater robotics

Location and topography of the Heihe River Basin, China.

<p>Location and topography of the Heihe River Basin, China.</p

Daily NPP for a 10-day period of Heihe River Basin.

<p>(a) DOY 131–140. (b) DOY 161–170. (c) DOY 191–200. (d) DOY 221–230. (e) DOY 251–260. (f) DOY 281–290.</p

Temporal dynamic patterns of modelled and ground based GPP during the growing season of 2012.

<p>(a) croplands. (b)orchard. (c)vegetable field. (d)wetland.</p

Spatial distribution of field sampling sites.

<p>Spatial distribution of field sampling sites.</p

Temporal dynamic patterns of modelled GPP generated with simulated daily LAI and FPAR together with ground based ones during the growing season of 2012.

<p>(a) croplands. (b) orchard. (c) vegetable field. (d) wetland. For modelled and ground-based values, error bars represent mean and maximum/minimum for GPP in a 10-day period.</p

Model test against ground-based GPP.

<p>(a) Relationship between estimated GPP and ground-based GPP. (b) Relationship between MODIS GPP and ground-based GPP (b).</p