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A Result on Fractional(a,b,k)-critical Covered Graphs 被引量:3
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作者 Si-zhong ZHOU 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2021年第4期657-664,共8页
A fractional[a,b]-factor of a graph G is a function h from E(G)to[0,1]satisfying a≤d^(h)_(G)(v)≤b for every vertex v of G,where d^(h)_(G)(v)=∑e∈E(v)h(e)and E(v)={e=uv:u∈V(G)}.A graph G is called fractional[a,b]-c... A fractional[a,b]-factor of a graph G is a function h from E(G)to[0,1]satisfying a≤d^(h)_(G)(v)≤b for every vertex v of G,where d^(h)_(G)(v)=∑e∈E(v)h(e)and E(v)={e=uv:u∈V(G)}.A graph G is called fractional[a,b]-covered if G contains a fractional[a,b]-factor h with h(e)=1 for any edge e of G.A graph G is called fractional(a,b,k)-critical covered if G—Q is fractional[a,b]-covered for any Q⊆V(G)with∣Q∣=k.In this article,we demonstrate a neighborhood condition for a graph to be fractional(a,b,k)-critical covered.Furthermore,we claim that the result is sharp. 展开更多
关键词 GRAPH NEIGHbORHOOD fractional[a 6]-factor fractional[a.6]-covered graph fractional(a.b k)-critical covered graph
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基于分数阶小波域GSM模型的地震信号随机噪声压制方法 被引量:6
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作者 汪金菊 李青 +1 位作者 徐小红 曹丽 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2018年第7期2989-2997,共9页
地震信号中的随机噪声是一种干扰波,严重降低了地震信号的信噪比,并影响着资料的后续处理和分析.本文根据地震信号中有效信号和随机噪声的差异,结合分数阶B样条小波变换与高斯尺度混合模型提出了一种地震信号随机噪声压制方法.首先利用... 地震信号中的随机噪声是一种干扰波,严重降低了地震信号的信噪比,并影响着资料的后续处理和分析.本文根据地震信号中有效信号和随机噪声的差异,结合分数阶B样条小波变换与高斯尺度混合模型提出了一种地震信号随机噪声压制方法.首先利用分数阶B样条小波变换将含噪地震信号映射到最优分数阶小波时频域内,然后对各小波子带系数分别建立高斯尺度混合模型,由贝叶斯方法估计出源地震信号小波系数,最后使用分数阶B样条小波逆变换重构得到降噪后的地震信号.利用本文方法对合成地震记录和实际地震信号进行降噪处理,实验结果表明本文方法能够有效地压制地震信号中的随机噪声,并且较好地保留了有效信号. 展开更多
关键词 地震信号 随机噪声 分数阶b样条小波 高斯尺度混合模型
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DTM Simulation of Peristaltic Viscoelastic Biofluid Flow in Asymmetric Porous Media: A Digestive Transport Model 被引量:4
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作者 Dharmendra Tripathi Osman Anwar Beg +2 位作者 Praveen Kumar Gupta Ganjam Radhakrishnamacharya Jagannath Mazumdar 《Journal of Bionic Engineering》 SCIE EI CSCD 2015年第4期643-655,共13页
A biofluid dynamics mathematical model is developed to study peristaltic flow of non-Newtonian physiological liquid in a two-dimensional asymmetric channel containing porous media as a simulation of obstructed digesti... A biofluid dynamics mathematical model is developed to study peristaltic flow of non-Newtonian physiological liquid in a two-dimensional asymmetric channel containing porous media as a simulation of obstructed digestive (intestinal) transport. The fractional Oldroyd-B viscoelastic rheological model is utilized. The biophysical flow regime is constructed as a wave-like motion and porous medium is simulated with a modified Darcy-Brinkman model. This model is aimed at describing the diges- tive transport in intestinal tract containing deposits which induce impedance. A low Reynolds number approximation is em- ployed to eliminate inertial effects and the wavelength to diameter ratio is assumed to be large. The differential transform method (DTM), a semi-computational technique is employed to obtain approximate analytical solutions to the boundary value problem. The influences of fractional (rheological material) parameters, relaxation time, retardation time, amplitude of the wave, and permeability parameter on peristaltic flow characteristics such as volumetric flow rate, pressure difference and wall friction force are computed. The present model is relevant to flow in diseased intestines. 展开更多
关键词 peristaltic transport fractional Oldroyd-b model porous medium differential transform method asymmetricchannel obstructed digestive flow
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非稳态分数阶Oldroyd-B流体绕楔形体流动研究 被引量:3
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作者 白羽 万飒 张艳 《计算力学学报》 CAS CSCD 北大核心 2023年第4期546-551,共6页
研究了非稳态分数阶Oldroyd-B流体在多孔介质中通过楔形拉伸板的驻点流动问题。基于分数阶Oldroyd-B流体的本构模型建立了动量方程,并在其中引入了浮升力和驻点流动特征。此外,考虑了具有热松弛延迟时间的修正的分数阶Fourier定律,并将... 研究了非稳态分数阶Oldroyd-B流体在多孔介质中通过楔形拉伸板的驻点流动问题。基于分数阶Oldroyd-B流体的本构模型建立了动量方程,并在其中引入了浮升力和驻点流动特征。此外,考虑了具有热松弛延迟时间的修正的分数阶Fourier定律,并将其应用于能量方程和对流换热边界条件。接着,采用与L1算法相结合的有限差分法求解控制偏微分方程。最后,分析了相关物理参数对流动的影响。结果表明,随着楔角参数的增加,流体受到的浮升力增大,导致速度加快;达西数越大,介质的孔隙度变大,流体的流动越快;此外,温度分布先略有上升后明显下降,这表明Oldroyd-B流体具有热延迟特性。 展开更多
关键词 非稳态流动 分数阶Oldroyd-b流体 多孔介质 热辐射 有限差分法
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A New Fractional Rational Bézier Curve
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作者 吴蓓蓓 顾传青 《Journal of Shanghai University(English Edition)》 CAS 2005年第3期216-218,共3页
Based on rational Bézier curves given by Ron Goldman, a new fractional rational Bézier curve was first defined in terms of fractional Bernstein bases. Moreover, some basic properties were dicussed and a theo... Based on rational Bézier curves given by Ron Goldman, a new fractional rational Bézier curve was first defined in terms of fractional Bernstein bases. Moreover, some basic properties were dicussed and a theorem connected to Poisson curves was obtained. Some examples in this paper were given by the visual results. 展开更多
关键词 fractional bernstein bases fractional rational bézier curves Poisson curves.
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双核素心肌显像对老年冠心病CTO病变PCI术的指导意义 被引量:6
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作者 武国东 孙明莉 王素侠 《中国实验诊断学》 2013年第7期1210-1213,共4页
目的评价99 Tcm-甲氧基异丁基异腈(99 Tcm-sestamibi,99 Tcm-MIBI)/18F脱氧葡萄糖(18F-fluorodeoxy glu-cose,18F-FDG)双核素心肌灌注/代谢显像技术(DISA)检测冠状动脉完全闭塞导致心力衰竭型冠状动脉粥样硬化性心脏病老年患者存活心肌... 目的评价99 Tcm-甲氧基异丁基异腈(99 Tcm-sestamibi,99 Tcm-MIBI)/18F脱氧葡萄糖(18F-fluorodeoxy glu-cose,18F-FDG)双核素心肌灌注/代谢显像技术(DISA)检测冠状动脉完全闭塞导致心力衰竭型冠状动脉粥样硬化性心脏病老年患者存活心肌对经皮冠状动脉支架术(Percutaneous coronary intervention,PCI)后心功能的改善情况。方法 41例经冠状动脉造影证实至少1支以上冠脉闭塞导致心力衰竭型冠心病的老年患者,PCI术前1周行99 Tcm-MI-BI/18F-FDG双核素心肌灌注/代谢显像检查,根据DISA结果,分为有心肌存活组和无心肌存活组。分别比较PCI术前后2组患者血浆BNP值及左室射血分数(LVEF)等心功能指标。结果有心肌存活组经PCI术后LVEF由41.12±5.97升至47.12±4.86,LVFS由16.79±5.64升至25.86±7.43,血NT-proBNP值由4287.25±401.56ng/L降至427.43±91.47ng/L;术前与术后比较,有显著统计学意义;无心肌存活组经PCI术后LVEF由40.03±3.48升至41.31±3.56,LVFS由16.35±5.86升至18.75±3.51,血NT-proBNP值由4495.32±347.72ng/L降至3827.53±97.28ng/L,术前与术后比较,无统计学意义。结论双核素心肌显像能有效检测冠状动脉完全闭塞致心力衰竭型冠心病老年患者存活心肌,而有存活心肌者PCI术后心功能得到明显改善。故双核素心肌显像对老年冠心病CTO病变行PCI术有指导意义。 展开更多
关键词 99Tcm-甲氧基异丁基异腈 18F脱氧葡萄糖 双核素心肌灌注 代谢显像技术 经皮冠状动脉支架术 左心室射血分数 左室短轴缩短率 b-型钠尿肽
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