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51.
Yawei Li Shaobai Sang Shengli Jin Chunyan Yang Nan Li 《Journal of Materials Science》2006,41(18):5815-5819
Synthesis of Mg-α-Sialon has been investigated by the mixture of silicon, aluminum and magnesia powders in a flowing nitrogen atmosphere in the range of 1300–1600 °C, when Mg-α-Sialon is designed with a chemical formulation of Mg
x
Si12−3x
Al3x
O
x
N16−x
in present work. The results showed that Mg-α-sialon initially occurred at 1400 °C and basically increased with elevated temperatures. For the samples of x = 0.6, 0.8 and 1.0 the products mainly consisted of Mg-α-Sialon with small amounts of Si, AlN and 21R AlN-polytypoid phases at 1600° C. However, in final products of x = 1.2, 1.4 and 1.6 only a little of Mg-α-Sialon formed and a great amount of Si remained in these samples at all the fired temperatures. Fortunately, the content of Mg-α-Sialon in these samples were obviously increased by adding a small amount of α-Si3N4 as seeds before nitridation. 相似文献
52.
正确高效的RAID6算法是RAID6磁盘阵列系统可靠运作的保障,算法的实现效率将直接影响整个系统的性能。笔者首先对RAID6的现有可行算法进行了分析,然后详细介绍了基于RDP算法的RAID6实现,最后用权威的Benchmark对该实现机制做出评估。 相似文献
53.
《Journal of the European Ceramic Society》2005,25(6):857-862
Compressive creep tests in air were carried out on 1 cat.% Fe-doped alumina at a temperature T=1400 °C. Iron doping affected the plastic deformation by different ways in relation with Fe2+ cations population. Fe2+ cations sped up the deformation rates. FeAl2O4 spinel precipitates were identified and they were found (i) to interact with alumina grain boundaries (ii) to limit the grain growth within a range of strain. The Fe2+ cations underwent oxidation and this resulted in the dissolution of the some precipitates and in the decrease of deformation rates. It was suggested that deformation sped up this evolution through mass transport and that time was not a dominating parameter. 相似文献
54.
针对用单片机控制机电一体化设备必须解决的抗干扰问题,提出了一些对策,旨在提高控制系统的自适应能力,从而做到可靠运行。 相似文献
55.
L. T. MO M. HUURMAN S. P. WU A. A. A. MOLENAAR 《Fatigue & Fracture of Engineering Materials & Structures》2007,30(9):823-831
Tensile fatigue behaviours of bitumen–stone adhesion were investigated using a dynamic mechanics analyser under stress‐controlled mode at two temperatures of 5 and 25°C and various controlled‐stress levels. Failure characteristics including interfacial failure and cohesive failure were examined using image analysis of fracture surfaces. Finite‐element analysis on stress distributions was conducted under different temperatures, film thickness and interfacial bonding conditions. A Coulomb–Mohr like criterion in combination with shear and normal stresses is proposed to deal with the extreme thin adhesive layer, which can be further simplified into an adhesive zone without significant loss of accuracy for stress analysis. 相似文献
56.
Y Ichinose 《Canadian Metallurgical Quarterly》1997,38(3):172-176
A clinical study was conducted to compare the analgesic effect of clonidine with those of sumatriptan and their mixture and their effects on hemodynamics. 40 patients undergoing elective total hysterectomy were randomly divided into 4 groups in terms of the epidurally administered drugs with 10 patients in each group (group C1: clonidine 150 micrograms, group C2: clonidine 75 micrograms, group S: sumatriptan 6 mg and group S + C: clonidine 75 micrograms + sumatriptan 3 mg). MAP, HR, SpO2, VT VAS, VRS and ePDT were measured in the initial 4 h. The demographic data and the doses of intraoperative local anesthetics among the 4 groups were not statistically different. It was found that no significant difference in the pre- and postadministration values of HR, SpO2 and VT. A obvious reduction of MAP appeared in the groups of C1 and C2, but in the other groups the hemodynamical parameters were stable. The groups of C1, C2 and S + C showed significant increase in VAS and VRS, along with increase of ePDT when compared with the pre-drug level. There was no obvious alteration in group S after the drug administration. It was concluded that (1) single use of sumatriptan is ineffective in the dose given in this study; (2) small dose (150 micrograms and 75 micrograms) of clonidine has epidurally analgesic effects; (3) combined use of sumatriptan and clonidine is an acceptable way in epidural analgesia, in terms of its analgesic effect and hemodynamic changes. 相似文献
57.
Huai Wen-xin Wuhan University of Hydraulic & Electric Engineering Wuhan Hubei P.R.China Prof.Li Wei 《水动力学研究与进展(B辑)》1993,(3)
Turbulence represents an essential aspect in atmospheric and oceanic circulations.In particu-lar,it is a preponderant factor in the dispersion of pollutants of artificial or natural origin.Thevertical turbulent jets,plumes and buoyant jets discharging into static environment is one of themost important and basic flow patterns related with the environment pollution.These flows havenumerous important applications,for example,thrust augmentors,waste disposal plumes fromstacks and combustion systems,and significant problems of turbulent diffusion. 相似文献
58.
LH Cohn 《Canadian Metallurgical Quarterly》1996,5(2):120-121
This paper presents 5 patients with repeated recurrence of osteosarcoma (RROS). The primary focus of 3 patients were in the distal portion of femur, and 2 patients were in the proximal portion of tibia. Three patients, whose chest X ray film were negative, were treated by amputation and chemotherapy. Two patients had isolated metastatic focus 1.5 cm in diameter in lung, were treated by amputation after 1 week of chemotherapy and then treated by lobectomy after 2 weeks of chemotherapy. After operation, the chemotherapy was carried out for 3 courses of treatment. The roentgenogram of chest and affected limb were taken once every two months. There were metastatic focuses found in the lung of 1 patient and in the distal portion of femur of 2 patients. One patient was operated on for 4 times. Up to now, 3 patients have been living for 5 years and 2 patients for 6 years after operation. 相似文献
59.
Fractal Nature of Crack Growth under Different Temperature 总被引:1,自引:0,他引:1
Qunsheng CAO 《材料科学技术学报》1996,12(2):143-148
We have studied numerically a simple crack growth model in a two-dimensional triangular lattice of bonds and nodes which incorporates the sudece of a growing crack bond-breaking probability Pi~ exp{(-Vi+Ei)φ(T)}, where Ei is elastic eneny stored in the i-th bond. Different energy temperature factors φ(T) are employed during crack formation and propagation process with a uniform dilation strain case and a shear case and with periodic boundary condition in the horizontal direction. Our results show that the patterns of the cracks generated are fractal structure and the effective fractal dimensionalities decrease with the increase of the temperature factor φ(T)(the absolute temperature T decreasing). In the paper we also discuss the relation between the effective fractal dimension Deff (the radius Rg Of gyration) and the fractal dimensions D (the radius R of circular), and also give their modification values Ω about two kinds of methods in the lattice model 相似文献
60.