Adaptive Robust Formation Control of Connected and Autonomous Vehicle Swarm System Based on Constraint Following.

This article proposes an adaptive robust formation control scheme for the connected and autonomous vehicle (CAV) swarm system by utilizing swarm property, diffeomorphism transformation, and constraint following. The control design is processed by starting from a 2-D dynamics model with (possibly fast) time varying but bounded uncertainty. The uncertainty bounds are unknown. For compact formation, the CAV system is treated as an artificial swarm system, for which the ideal swarm performance is taken as a desired constraint. By this, formation control is converted into a problem of constraint following and then a performance measure ß is defined as the control object to evaluate the constraint following error. For collision avoidance, a diffeomorphism transformation on space measure between two vehicles is creatively performed, by which the space measure is positive restricted. For uncertainty handling, an adaptive robust control scheme is proposed to render the ß -measure to be uniformly bounded and uniformly ultimately bounded, that is, drive the controlled (CAV) swarm system to follow the desired constraint approximatively. As a result, the system can achieve the ideal swarm performance; thereout, compact formation is realized, regardless of the uncertainty. The main contribution of this article is exploring a 2-D formation control scheme for (CAV) swarm system under the consideration of collision avoidance and time-varying uncertainty.

A canonical form of the equation of motion of linear dynamical systems.

The equation of motion of a discrete linear system has the form of a second-order ordinary differential equation with three real and square coefficient matrices. It is shown that, for almost all linear systems, such an equation can always be converted by an invertible transformation into a canonical form specified by two diagonal coefficient matrices associated with the generalized acceleration and displacement. This canonical form of the equation of motion is unique up to an equivalence class for non-defective systems. As an important by-product, a damped linear system that possesses three symmetric and positive definite coefficients can always be recast as an undamped and decoupled system.

Feasibility study of a partially hollow configuration for zirconia dental implants.

PURPOSE: To assess the feasibility of a new shape configuration involving a partially hollow and porous lower part for dental implants. MATERIALS AND METHODS: Cylindrical zirconia dental implants coated with bioactive glass were fabricated in the laboratory. Each implant has a solid upper part and a partially hollow lower part. It is open at the bottom with holes through the lower cylindrical walls. This hollow and porous configuration permits bone growth into the lower part of the implant that, over time, forms an interlinked network to lock the implant into the alveolar bone. Biomechanical properties of the new design were evaluated through material testing and experiments with dogs. RESULTS: Mechanical testing of bending strength, hardness, fracture toughness, and fatigue life indicated that zirconia implants with the proposed partially hollow configuration can be fabricated to have structural properties comparable to or exceeding the usual requirements for implants. Animal testing suggests that there is appreciable improvement in lock-in strength and osteointegration due to the hollow and porous configuration. CONCLUSION: The new shape configuration is biomechanically feasible and further research is warranted to improve the design for human use.

A proteomic analysis of rice seedlings responding to 1,2,4-trichlorobenzene stress.

The proteomic analysis of rice (Oryza sativa L.) roots and leaves responding to 1,2,4-trichlorobenzene (TCB) stress was carried out by two dimensional gel electrophoresis, mass spectrometric (MS), and protein database analysis. The results showed that 5 mg/L TCB stress had a significant effect on global proteome in rice roots and leaves. The analysis of the category and function of TCB stress inducible proteins showed that different kinds of responses were produced in rice roots and leaves, when rice seedlings were exposed to 5 mg/L TCB stress. Most responses are essential for rice defending the damage of TCB stress. These responses include detoxication of toxic substances, expression of pathogenesis-related proteins, synthesis of cell wall substances and secondary compounds, regulation of protein and amino acid metabolism, activation of methionine salvage pathway, and also include osmotic regulation and phytohormone metabolism. Comparing the TCB stress inducible proteins between the two cultivars, the beta-glucosidase and pathogenesis-related protein family 10 proteins were particularly induced by TCB stress in the roots of rice cultivar (Oryza sativa L.) Aizaizhan, and the glutathione S-transferase and aci-reductone dioxygenase 4 were induced in the roots of rice cultivar Shanyou 63. This may be one of the important mechanisms for Shanyou 63 having higher tolerance to TCB stress than Aizaizhan.