In order to handle the non-linear system and the complex disturbance in marine engines, a finite-time convergence active disturbance rejection control (ADRC) technique is developed for the control of engine speed. First, a model for the relationship between engine speed and fuel injection is established on the basis of the mean value engine model. Then, to deal with the load disturbances and model parameter perturbation of the diesel engine, this paper designs an ADRC approach to achieve finite-time stability. Finally, simulation experiments show that the proposed method has better control effect and stronger disturbance rejection ability in comparison with the standard linear ADRC.
Dissipative particle dynamics simulations are performed to study the self-assembly of rod-coil (RC) diblock copolymers confined in a slit with two coil-selective surfaces. The effect of rod length and slit thickness on the assembly structure is investigated. A morphological phase diagram as a function of slit thickness and rod length is presented. We observe several ordered structures, such as perpendicular cylinders, parallel cylinders, and puck-shaped structure. In the assembly structures, long-range rod-rod orientational order is observed when the rod length exceeds a critical rod length. Our results show that the coil-selective slit influences the assembly structure as well as the rod orientation of RC diblock copolymers.
Omi/HtrA2 is a serine protease present in the mitochondrial space. When stimulated by external signals, HtrA2 is released into the mitochondrial matrix where it regulates cell death through its interaction with apoptotic and autophagic signaling pathways. Omi/HtrA2 is closely related to the pathogenesis of neurological diseases, such as neurodegeneration and hypoxic ischemic brain damage. Here, we summarize the biological characteristics of Omi/HtrA2 and its role in neurological diseases, which will provide new hints in developing Omi/HtrA2 as a therapeutic target for neurological diseases.
The objective of this study was to investigate how a stress wave travels in a standing tree as it is introduced into the tree trunk through a mechanical impact. A series of stress wave time-of-flight (TOF) data were obtained from three freshly-cut red pine (Pinus resinosa Ait.) logs by means of a two-probe stress wave timer. Two-dimensional (2D) and three-dimensional (3D) stress wave contour maps were constructed based on the experimental data using a commercial software. These stress wave contour maps represent the wave fronts in a time sequence, illustrating the flow of stress wave energy within a log. The analysis of TOF data and wave fronts indicates that stress wave propagation in standing trees is affected by tree diameter, travel distance, and internal wood conditions (wood properties and structural defects). When a stress wave is introduced into a tree trunk from a point source, it initially propagates in the impact direction as a 3D wave. Then the flow of the stress wave energy gradually changes towards the longitudinal directions. As the diameter-to-distance ratio reaches 0.1 or below, the wave begins to travel as a quasi 1D wave.
This study proposes the establishment of a knowledge-system ontology in the nursing field. It uses advanced data mining techniques, digital publishing technologies, and new media concepts to comprehensively integrate and deepen nursing knowledge and to aggregate sources of knowledge in specialized technical fields. This study applies all forms of media and transmission channels, such as personal computers and mobile devices, to establish a knowledge-transmission system that provides knowledge services such as knowledge search, update retrieval, evaluation, questions and answers (Q&As), online viewing, information subscription, expert services, push notifications, review forums, and online learning. In doing so, this study creates an authoritative and foundational knowledge service engine for the nursing field, which provides convenient, flexible, and comprehensive knowledge services to members of the nursing industry in a digital format.
An ab initio method based on the density functional theory has been employed to investigate the behaviours of the bimetallic Ag2-doped silicon clusters at a size of n = 1 - 11. The possible geometrical configurations, growth-pattern behaviours, stabilities, energy gaps, and electronic properties are presented and discussed. The optimized geometries reveal that the silicon atom surface-capped and silver atom substituted 3D structures are dominant growth patterns. The calculated averaged binding energy, fragmentation energy, and the second-order difference of energy manifest that the most stable structures of Ag2Sin (n = 1 - 11) clusters are Ag2Si2 and Ag2Si5 isomers, which is in qualitative agreement with the AgSin clusters. In addition, the gap between highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) exhibits that the Ag2Si3 and Ag2Si5 isomers have dramatically enhanced chemical stability. Natural population analysis shows that the charge-transfer phenomena are coincidence with the AgSin clusters but different from Mo2Sin systems. Furthermore, the dipole moments of stable Ag2Sin (n = 1 - 11) display a pronounced odd-even oscillation with the number of silicon atoms.