盘式制动器尖叫声单模态和多模态不稳定性非线性稳态动力学的研究(二)

本文重点说明和讨论制动系统承受摩擦诱导的振动,由于多不稳定模式可能发生的非线性动力学特性。采用具有摩擦副的有限元模型分析制动系统的稳定性和预测尖叫声稳态非线性波动。尖叫声不稳定机理看成是一模式偶合现象,它通常看成为一种组合。     

盘式制动器尖叫声单模态和多模态不稳定性非线性稳态动力学的研究(一)

本文重点说明和讨论制动系统承受摩擦诱导的振动,由于多不稳定模式可能发生的非线性动力学特性.采用具有摩擦副的有限元模型分析制动系统的稳定性和预测尖叫声稳态非线性波动.尖叫声不稳定机理看成是一模式偶合现象,它通常看成为一种组合.     

3D modeling of uranium-bearing solution-collapse breccias in Proterozoic sandstones (Athabasca Basin,Canada)—Metallogenic interpretations

Unconformity-related uranium deposits are the highest grade, large tonnage uranium resources in the world. In the Athabasca Basin (northern Saskatchewan, Canada), which is the premier host for unconformity-type deposits, the ore deposits are frequently hosted and surrounded by breccias in sandstone. The significance of these breccias and their relation to mineralization are of major importance for the genesis of these high-grade deposits. Therefore, a modeling study, integrating results from structural geology and petrology, was performed with the gOcad 3D modeling software, in order to decipher geometrical and geological relationships between breccias, faults and mineralization zones. Mineralized bodies and the sudoite–dravite breccia bodies display strong spatial correlations. They appear to be controlled by reverse shear zones cross-cutting the unconformity and containing graphite in the basement. Geochemical computations evidenced that volumetric water–rock ratios up to 10,000 could be obtained in these breccia bodies for volume losses of up to 90%. Assuming reasonable values for quartz saturation, hydraulic conductivity and connected porosity, the minimal fluid volume and the time duration necessary to generate the sudoite–dravite breccia bodies were estimated at ca. 2 km³ and ca. 1 Myr, respectively. The comparison of these results with literature data suggests that the formation of sudoite–dravite breccia and mineralization could have been coeval. It may be proposed that within the space created by the quartz dissolution in the breccia body, a mixing between basement and basinal fluids could have induced U deposition and allowed the development of high-grade mineralization. The first-order uranium solubility that this coeval formation would imply is consistent with literature data, which suggests that this conceptual model is reasonable.     

Hepatitis G and C viruses respond to interferon-alpha with different virologic kinetics

The aim of this work was to specify the time course of response to interferon (IFN) of hepatitis G virus (HGV) and hepatitis C virus (HCV) in coinfected individuals. A group of 33 patients, undergoing 12 months of IFN therapy for chronic hepatitis C, was screened for the presence of both HGV and HCV RNAs to select seven coinfected patients. Spontaneous recovery from HGV infection was excluded through the detection of antibodies to the envelope-2 protein of HGV and HCV isolates were genotyped. Within three months of treatment, we found that HGV RNA was transiently cleared in 6/7 patients, but the rate of long-term favorable response was very low (1/7). In addition, considering the same individuals separately, it was shown that HGV and HCV responded to IFN with different kinetics in 5/7 patients. Taken together, these results underscore the importance of the virological basis of the resistance to IFN treatment.     

Stability of hydrogen incorporated in ZnO nanowires by plasma treatment

The stability of hydrogen in ZnO is studied using hydrogenated nanowires by plasma treatment. Enhanced near band edge UV emission and reduced defect level green emission is observed after hydrogen plasma treatment. Through thermal stability tests, this effect is found to be stable at room temperature and nearly stable up to ~500 K, but begins to deteriorate at higher temperature. The study of the irradiation stability of the hydrogen in ZnO nanowires shows that the hydrogen is stable under an electron beam with an accelerating voltage lower than 5 kV, but is not stable under 10 kV or under an intensive laser beam. The results could benefit the further understanding of the role of hydrogen in ZnO and light-emitting devices based on hydrogenated ZnO.     

A new method to quantify retention-failed cells of an EEPROM CAST

The cell array stress test (CAST) is a very simple tool to study one of the main issues of Non Volatile Memory reliability: data retention. However, it is not possible to easily quantify and localise the retention-failed cells of a CAST. Thus, a new experimental technique to localize and to quantify retention-failed EEPROM cells into a CAST is presented in this paper. This new technique is based on light emission microscopy; the aim is to observe light emission coming from cells and to localize their position with accuracy on CAST area. It is a visual and non destructive method which validity has been shown on cycled cells after a retention test.     

Effects of landscape structure on vegetation and some animal groups after agriculture abandonment

This research was carried out on the montane belt of a south-exposed watershed in the Intermediary Alps which have been hit by agriculture abandonment. The aim of the study was to study the relationships between vegetation, landscape mosaic, and two kinds of animals using this space at different scales: roe deer (Capreolus capreolus) and earthworms (lumbricids). Landscape dynamics (post-cultural recolonisation) and landscape structure have been approached by means of the Arc/Info geographical information system (GIS). Several methods used to study on one hand roe deer distribution, and, on the other, earthworm abundance and diversity are developed. Of these, in particular, GIS processing is used to sample earthworms according to vegetation dynamics, and roe deer distribution is related to landscape heterogeneity. Earthworms are more abundant and diversified in the key steps of vegetation dynamics. These lumbricids can be considered as functional indicators of these dynamics. Results also demonstrate that both the vegetation type and the landscape heterogeneity have a direct influence on the use of the space by the roe deer. They show themselves to be structural indicators of the landscape.