Distributed Adaptive Fixed-Time Fault-Tolerant Control for Multiple 6-DOF UAVs With Full-State Constraints Guarantee

In contrast with most existing results concerning unmanned aerial vehicles (UAVs) wherein material points or only attitude/longitudinal dynamics are considered, this article proposes a distributed fixed-time fault-tolerant control methodology for networked fixed-wing UAVs whose dynamics are six-degree-of-freedom with twelf-state-variables...

A multi-axis robot-based bioprinting system supporting natural cell function preservation and cardiac tissue fabrication

Despite the recent advances in artificial tissue and organ engineering, how to generate large size viable and functional complex organs still remains as a grand challenge for regenerative medicine. Three-dimensional bioprinting has demonstrated its advantages as one of the major methods in fabricating simple tissues, yet it still faces...

New insights into long-term chloride transport in unsaturated cementitious materials: Role of degree of water saturation

Concrete is rarely saturated. Reliable durability design of marine concrete structures requires a solid understanding of the long-term chloride transport in unsaturated concretes. This paper presents a critical analysis of the time-dependent chloride diffusion coefficient in unsaturated cementitious materials exposed to marine environment....

Dependence of unsaturated chloride diffusion on the pore structure in cementitious materials

Conceptual analysis is performed to examine the effects of pore features on the water continuity in unsaturated porous systems. The roles of pore features in relative chloride diffusion coefficient (D_rc) of mortar specimens at various degrees of water saturation (S_w) were studied based on mercury intrusion porosimetry...

A model for predicting the relative chloride diffusion coefficient in unsaturated cementitious materials

An analytical model for predicting the relative chloride diffusion coefficient in cementitious materials at different degrees of water saturation is presented in this paper. The model is developed based on the Nernst-Einstein equation and conductivity of cementitious electrolyte, as well as on moisture distribution in the pore structure. Good...

Non-saturated Chloride Diffusion in Sustainable Cementitious Materials

Chloride-induced reinforcement corrosion, caused by chloride diffusion in the unsaturated concrete cover, is a major durability problem of concrete structures. Current concepts for concrete mixture design and for service life prediction are generally based on the understanding of the chloride diffusion coefficient of saturated concrete. This...

Climate-driven seasonal geocenter motion during the GRACE period

Annual cycles in the geocenter motion time series are primarily driven by mass changes in the Earth’s hydrologic system, which includes land hydrology, atmosphere, and oceans. Seasonal variations of the geocenter motion have been reliably determined according to Sun et al. (J Geophys Res Solid Earth 121(11):8352–8370, 2016) by combining the...

Chloride transport in partially saturated mortar made of blended cement

Due to environmental (low CO2 emission) and economic benefit, supplementary cementitious materials (SCMs) have been widely used in reinforced concrete structures. However, the question from engineering practice is to which extend these blended mixtures do meet the future durability criteria. Chloride ingression is nowadays considered as the main...