Guaranteed control of a robotic excavator during digging process Gurko, Alexander; Sergiyenko, Oleg; Nieto Hipolito, Juan Ivan ...
2015 12th International Conference on Informatics in Control, Automation and Robotics (ICINCO),
2015-July, Letnik:
2
Conference Proceeding
Automation of excavators offers a promise for increasing productivity of digging. At the same time, it's a highly difficult issue due to presence of various nonlinearities and uncertainties in ...excavator mechanical structures and hydraulic actuators, disturbance when a bucket contacting the ground etc. This paper concerns the problem of robust trajectory tracking control of an excavator arm. To solve this problem, the computed torque control with the guaranteed cost control is considered. The mathematical tool of R-functions as an alternative to the linear matrix inequality approach to constructing information sets of an excavator arm state is used. Simulation results and functional ability analysis for the proposed control system are given.
The phenomenon of unstable expression of gap junction's proteins connexins remains a "visiting card" of astrocytic tumors with various degrees of malignancy. At the same time, it stays unclear what ...is detected by the positive expression of connexins in astrocytic tumors: gap junctions, hemi-channels, or connexin proteins in cytosol. In the present work, for the first time, we demonstrate an ultrastructural evidence of gap junctions in pleomorphic xanthoastrocytoma, a rare primary brain tumor, the intercellular characteristics of which are poorly studied and remain very discursive and controversial. The primary tumor mass was resected during craniotomy from a 57-old patient diagnosed with pleomorphic xanthoastrocytoma Grade II based on the histopathological analysis. The immunohistochemical study was conducted with primary antibodies: Neurofilament, Myelin basic protein, Glial fibrillary acidic protein, and Synaptophysin. For electron microscopic examination fragments of tumor tissue were fixed in a glutaraldehyde, postfixed in a 1% OsO
4
, dehydrated and embedded into resin. After the detailed clinical, histological, and immunohistochemical study we revealed some ultrastructural characteristics of the tumor, as well as the first evidence of direct intercellular connection between the tumor cells via gap junctions. Regularly arranged gap junctions connected the somas of xanthastrocytes with dark cytoplasm containing lipid drops. Besides the localization between the cell bodies, from one to several gap junctions were found between the branches of xanthoastrocytoma in tumor intercellular space in close proximity to tumor cell. Our results may indicate gap junctions as a possible structure for intercellular communication between pleomorphic xanthoastrocytoma cells.
Recent structure determinations suggested a new binding site for a non-redox active metal ion in subunit I of cytochrome
c oxidase both of mitochondrial and of bacterial origin. We analyzed the ...relevant metal composition of the bovine and the
Paracoccus denitrificans enzyme and of bacterial site-directed mutants in several residues presumably liganding this ion. Unlike the mitochondrial enzyme where a low, substoichiometric content of Ca
2+ was found, the bacterial wild-type (WT) oxidase showed a stoichiometry of one Ca per enzyme monomer. Mutants in Asp-477 (in immediate vicinity of this site) were clearly diminished in their Ca content and the isolated mutant enzyme revealed a spectral shift in the heme
a visible absorption upon Ca addition, which was reversed by Na ions. This spectral behavior, largely comparable to that of the mitochondrial enzyme, was not observed for the bacterial WT oxidase. Further structure refinement revealed a tightly bound water molecule as an additional Ca
2+ ligand.
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