Nonlinear Model Predictive Control of Shipboard Boom Cranes Based on Moving Horizon State Estimation

As important equipment in offshore engineering and freight transportation, shipboard cranes, working in non-inertial coordination systems, are complicated nonlinear systems with strong couplings and typical underactuation. To tackle the challenges in the controller design for shipboard boom cranes, which is a representative type of shipboard cranes, a comprehensive framework embedding moving horizon estimation (MHE) in model predictive control (MPC) is constructed in this paper while considering disturbances and noise. By utilizing MHE, velocity information can be estimated with high precision even though this is influenced by disturbances and measurement noises. This expected superiority can greatly ease the difficulties in directly measuring all states of shipboard boom cranes. Then, the estimated information can be passed to MPC to derive the optimal control law by solving a constrained optimal problem. During this process, the physical limits of shipboard boom cranes are fully considered. Therefore, the practicability of the proposed framework is highly suitable for the actual requirements of shipboard boom cranes. Finally, the framework is verified by designing three typical scenarios with different disturbances and/or noises. Comparisons with other control approaches are also performed to demonstrate the effectiveness

Mechanism of M23C6 → M7C3 carbides reaction of Cr35Ni45Nb type alloy during carburization

The carbide transformation of Cr35Ni45Nb type alloy during service has been investigated in the present work. The primary carbide of the as-cast Cr35Ni45Nb type alloy is M _7 C _3 (M is mainly Cr element) and NbC, which transformed into M _23 C _6 type carbides (M is mainly Cr element) and G phase(Ni _16 Nb _6 Si _7 ) after service, respectively. The G phase and M _23 C _6 carbides mix together and grow up with each other during service. After carburization, the crystal structure of M _23 C _6 type carbide changes again and transforms into M _7 C _3 type carbide. The mechanism of M _23 C _6  → M _7 C _3 carbide reaction is an in situ transformation; the M _7 C _3 type carbide preferentially nucleates at the interface of M _23 C _6 / γ and grows toward the M _23 C _6 type carbide interior. With the diffusion of free carbon atoms into the M _23 C _6 type carbides, the M _23 C _6 type carbides are gradually surrounded by the M _7 C _3 type carbides until they are completely changed into M _7 C _3 type carbides

Microstructure damage of directionally solidified alloy turbine blade after service

Turbine blades are the most demanding components in aircraft engines, and their performance is related to the safety of the whole engine. Due to the complex service environment and harsh service conditions of blades, various types of damage cannot be prevented in service. Therefore, it is of great engineering and economic significance to study the service damage of blades. In this paper, the directional solidification alloy turbine blade after actual service was selected as the research object. The cross section position of 80% upper height of the blade was intercepted, and the qualitative and quantitative microstructure analysis was carried out by SEM and EDS analysis. The results show that there are two different types of γ' phases in this leaf. One kind of γ' phase has small size and regular shape, the other has large size and irregular shape. The degree of microscopic damage among different parts of the blade is characterized with the help of dimensional distribution characterization of the γ' phase of each part, combined with the analysis of hardness testing of each part of the cross-section.The results show that the service conditions of different parts are different, and the degree of microstructure damage is different. In addition, matrix crack and coating crack in some parts of blade are summarized and analyzed

Supplementary document for High-efficiency upconversion luminescence in UCNPs/CsPbBr3 nanocomposites enhanced by silver nanoparticles - 6838552.pdf

Supplemental material