Wyniki wyszukiwania - Biblioteka Nauki

1

The study of residual stresses in cold drawn steel wire by means of X-ray diffraction and finite element simulation

100%

Van Houtte P. , He S. , Mei F. , Sarban A.

Hutnik, Wiadomości Hutnicze

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2005

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tom Vol. 72, nr 2

133-136

EN

Residual stresses caused by cold drawing of low carbon steel wires have been studied. A wire was drawn from 20 mm diameter until 18 mm in one pass. An elastoplastic FEM simulation was performed using several constitutive models for the material. One of them takes the anisotropy due to the crystallographic texture into account. The predicted residual stresses were then compared with those obtained by X-ray diffraction measurements. A good agreement was found.

PL

W pracy przedstawiono analizę naprężeń własnych otrzymanych w procesie ciągnienia drutów wykonanych ze stali niskowęglowej. Drut ciągnięto ze średnicy 20 mm na średnicę 18 mm w jednym ciągu. Przedstawiono wyniki symulacji komputerowej opartej na metodzie elementów skończonych dla elastoplastycznego modelu odkształcenia ciała, użyto kilku modeli konstytutywnych materiału. Jeden z nich uwzględniał anizotropię związaną z teksturą krystalograficzną. Przewidywane naprężenia własne porównano z otrzymanymi z pomiarów dyfrakcji promieniowania rentgenowskiego i otrzymano dużą zgodność wyników.

2

A robust tracking control scheme for a class of nonlinear systems with fuzzy nominal model

100%

Mei F. , Zhihong M. , Yu X. , Nguyen T.

Applied Mathematics and Computer Science

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1998

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tom Vol. 8, no 1

145-158

EN

A novel robust tracking control scheme is proposed for a class of nonlinear systems. It is shown that a nonlinear system is first approximated by a fuzzy nominal model by aggregating a set of linearized local subsystems and then a conventional linear feedback controller is designed to stabilise the nominal system. In order to obtain good tracking performance for the controlled nonlinear system, a variable structure compensator is introduced to eliminate the effects or the approximation error and uncertainties between the fuzzy nominal model and the nonlinear system. A simulation example using a one-link rigid robotic manipulator is given in support of the proposed control scheme.

3

Physiological mechanism of programmed cell death aggravation and acceleration in wheat endosperm cells caused by waterlogging

75%

Yu M. , Zhou Z. , Deng X. , Li J. , Mei F. , Qi Y.

Acta Physiologiae Plantarum

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2017

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tom 39

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nr 01

4

The effects of different pharmacological agent treatments on ROS accumulation and functional protein activities in wheat endosperm PCD

63%

Lin Z. , Qi Y. , Liu D. , Mao F. , Deng X. , Li J. , Mei F. , Zhou Z.

Acta Physiologiae Plantarum

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2019

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tom 41

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nr 05

EN

Wheat (Triticum aestivum L.) is one of the top three food crops in the world. Studies have revealed that wheat endosperm development undergoes programmed cell death (PCD) process development that may be influenced by PCD. Waterlogging and exogenous hydrogen peroxide (H₂O₂) treatment exacerbates wheat endosperm PCD, whereas PCD acceleration is significantly inhibited by reactive oxygen species (ROS) scavengers. To explore the physiological mechanism of waterlogging resistance in wheat, the effects of exogenous H₂O₂, ascorbic acid (AsA), and cyclosporin A (CsA) treatment on ROS content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity in the endosperm of Huamai 8 (waterlogging-tolerant wheat cultivar) and Huamai 9 (waterlogging-sensitive wheat cultivar) were studied. The results showed that exogenous H₂O₂ treatment resulted in an increase in ROS content, antioxidant enzyme activity, mitochondrial membrane permeability, release of cytochrome c, and caspase-like protease activity in the endosperms of both wheat cultivars, which eventually exacerbated PCD. Compared to Huamai 8, the increase in ROS content in Huamai 9 was more significant, whereas changes in antioxidant enzyme activity, cytochrome c release, mitochondrial membrane permeability, and caspase-like protease activity were smaller. Exogenous AsA treatment leads to the content of H₂O₂ and catalase activity decrease, which could inhibit endosperm cell death to some extent. CsA treatment effectively inhibited the increase in H₂O₂ content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity caused by exogenous H₂O₂ treatment, which in turn inhibited cell death. In summary, exogenous H₂O₂ treatment aggravates endosperm PCD, and Huamai 9 exhibited higher ROS accumulation and a weaker antioxidant enzyme system under external stress, which may be the mechanisms underlying its sensitivity to waterlogging. CsA effectively inhibited the increase in ROS, antioxidant enzyme activity, cytochrome c release, and cell death. It is possible that in wheat endosperm, mitochondria in a similar way to animal mitochondria release cytochrome c regulating PCD.