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研究了含同原因故障的由两个不同型的平行部件和一个冷储备部件所组成的系统.通过选取空间并定义算子,将系统模型转化成抽象Cauchy问题.运用C_0半群和预解正算子理论,验证了系统主算子A为稠定的预解正算子,计算出了A的谱界为一c,同时得出了算子A的共轭算子及其定义域,最终利用共尾理论证得算子A的谱界和增长界相等,即为-c. 相似文献
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Xian-meng Zhang Dong-ming Zhang Chin Jian Leo Guang-zhi Yin Dan Feng D. S. Liyanapathirana 《Transport in Porous Media》2017,117(3):465-480
Coalbed methane, a naturally occurring gas in coal, is regarded as a relatively clean-burning and eco-friendly resource. During mining, coalbed methane may be leaked to the environment, leading to potential coal mine catastrophes such as coal and gas outbursts, and gas explosions. In the interest of mine stability, and to enhance resource recovery and utilisation, it is fundamentally important to understand the permeability characteristics of coal, in particular its post-peak permeability behaviour. In this paper, an in-house developed tri-axial apparatus with the ability to investigate coupled thermal–hydrological–mechanical behaviour under servo-controlled seepage has been used to carry out a series of gas permeation experiments in coal samples. The coal samples were subjected to tri-axial tests, including the simulation of coal extraction by unloading the confining pressure applied on the test specimens. The deformation and permeability characteristics of raw coal during these tests were recorded. The volume changes of the coal samples during the tests were observed to occur in three stages: Stage 1: contraction, Stage 2: little or no volume change, and Stage 3: dilation. Corresponding to the volume changes, the gas seepage can also be divided into three stages: seepage decrease, steady seepage, and accelerated seepage. Based on the observed behaviour of coal samples during the tri-axial permeation tests, an analytical model to simulate damage evolution and its effect on the permeability of coal containing gas is proposed in this paper. It may be used to study the evolution of permeability with stress changes, and to provide insights into coal and gas outbursts in practice. 相似文献
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以稻草秸秆为原料,经粉碎后进行全植物秸秆的乙酰化改性,再用此乙酰化稻草同ε-己内酯(ε-CL)接枝共聚合成乙酰化稻草/聚己内酯接枝共聚物(ACSW-g-PCL)。研究了反应时间、反应温度、及单体用量对接枝率(G%)的影响。在反应温度140℃,反应时间10h,ε-CL对乙酰化稻草的质量比2:1时获得的接枝率最大为39%。产物的结构和性能通过红外光谱、核磁共振、扫描电镜、X-射线衍射和热分析仪表征,结果表明乙酰化稻草秸秆已成功接枝上聚己内酯(PCL)链段,经接枝ε-CL改性后的ACSW-g-PCL热稳定性有所改善,并具有了一定的热塑性。 相似文献
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根据已知的FC-空间上的KKM型定理得出若干个相交定理,作为它们的应用,利用转移开闭映射的特征讨论广义变分不等式解的存在问题.本文的结果改进和推广了文献中的相应结论. 相似文献
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对无限大导体表面,楔形导体表面,半圆柱形凸起表面电荷面密度进行了具体的计算,结果表明在静电平衡的条件下导体表面虽曲率相同,但表面电荷面密度却可以不同. 相似文献
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通过对40例疤痕组织和正常皮肤组织的ETIR光谱比较分析发现,由于个体差异,其光谱均可分为三种不同类型。此外,疤痕组织中的胶原、蛋白质、核酸和脂类等生物大分子的吸收峰强度均在不同程度上高于正常皮肤组织,但两者的A_(1083)/A_(1548)并无明显差异。提示疤痕组织中的细胞仍属正常生长,治疗中不应损伤。 相似文献
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Li X Liu Z Zhang XF Wang LJ Zheng YN Yuan CC Sun GZ 《Molecules (Basel, Switzerland)》2008,13(8):1530-1537
A bioassay-guided in vitro screen has revealed that a 70% methanol extract of the leaves of Salix matsudana shows considerable inhibitory activity against cyclooxygenases (COX-1 and COX-2). A subsequent phytochemical study led to the isolation of a new flavonoid, matsudone A (1), together with five known flavonoids--luteolin (2), isoquercitrin (3), 7-methoxyflavone (4), luteolin 7-O-glucoside (5), 4',7-dihydroxyflavone (6)--and two phenolic glycosides, leonuriside A (7) and piceoside (8). Their structures were elucidated on the basis of extensive 1D- and 2D-NMR studies, high resolution ESI mass spectroscopic analyses and comparisons with literature data. The isolated compounds 1-8 were tested for their inhibitory activities against COX-1 and COX-2. Compounds 1, 5 and 6 were found to have potent inhibitory effect on COX-2 and compounds 3-5 exhibited moderate inhibition against COX-1. 相似文献
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【目的】研究不同缓冲体系对以玉米醇溶蛋白为载体制备的具有缓释性能的伊维菌素微球片剂药物溶出速度的影响;【方法】体外模拟大鼠胃肠道环境,测定伊维菌素微球片剂在不同缓冲体系中药物溶出以及释放动力学;【结果】在0.1mol/LHCl和磷酸氢二钠-柠檬酸缓冲液(pH=2.2)中,2h药物溶出率分别为19.60±0.95%和25.62±5.17%(p>0.05);在0.1mol/LHCl 0.32%胃蛋白酶(w/v)、磷酸氢二钠-柠檬酸缓冲液(pH=2.2) 0.075%胃蛋白酶(w/v)和磷酸氢二钠-柠檬酸缓冲液(pH=2.2) 0.0375%胃蛋白酶(w/v)中,2h药物溶出率分别为62.00±3.76%、74.18±8.26%和64.61±3.20%;在含有大鼠5%胃内容物的0.1mol/LHCl体系中,IVM在2h内溶出的百分率为42.27%,然后转移到含有大鼠4%小肠内容物的PBS体系中继续溶出3h,溶出百分率为88.03%;【结论】胃蛋白酶可以加速伊维菌素从微球片剂中的溶出。 相似文献
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