Effect of ultra-fine fly ash on the mechanical and shrinkage properties of ultra-high performance concrete

This paper reports on a study to determine the possibility of using ultra-fine fly ash (UFA) for partial or total replacement of normal fly ash (NFA) in ultra-high performance concrete (UHPC). Workability, microstructure, porosity, drying shrinkage as well as mechanical properties were comprehensively studied to investigate the influence of UFA...

Comparison of three control structures for inducing higher-order sliding modes

For mitigating the chattering effect in the sliding mode control (SMC), many adaption mechanisms have been proposed to reduce the switching gains. However, less attention is paid to the control structure, which influences the resulting uncertainty term and determines the minimum possible gains. This paper compares three control structures for...

Active gust load alleviation of high-aspect ratio flexible wing aircraft

This paper presents a novel active gust load alleviation approach within a multi-objective flight control framework developed by NASA for a flexible wing aircraft. The aircraft model is based on the NASA Generic Transport Model (GTM). The wing structures incorporate an aerodynamic control surface known as the Variable Camber Continuous...

Flexible Aircraft Gust Load Alleviation with Incremental Nonlinear Dynamic Inversion

In this paper, an Incremental Nonlinear Dynamic Inversion (INDI) controller is<br/>developed for the flexible aircraft gust load alleviation (GLA) problem. First, a flexible aircraft model captures both inertia and aerodynamic coupling effects between flight dynamics and structural vibration dynamics is presented. Then an INDI GLA controller is...

Stability Analysis for Incremental Nonlinear Dynamic Inversion Control

As a sensor-based control approach, the Incremental Nonlinear Dynamic Inversion (INDI) method has been successfully applied on various aerospace systems and shown desirable robust performance to aerodynamic model uncertainties. However, its previous derivations based on the so-called time scale separation principle is not mathematically rigorous...

Gust Load Alleviation and Ride Quality Improvement with Incremental Nonlinear Dynamic Inversion

A process-based approach to sediment transport in the Yangtze estuary

A process-based model for the Yangtze Estuary is constructed to study the sediment transport in the estuary. The proposed model covers the entire tidal region of the estuary, the Hangzhou Bay and a large part of the adjacent sea. The dominant processes, fluvial and tidal, are included in the model. The calibration of the model against extensive...