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101.
极坐标中应力与应力函数之间的关系 总被引:2,自引:1,他引:1
在极坐标下,通过极坐标的应力平衡方程推导出极坐标应力()与应力函数之间的关系. 相似文献
102.
103.
论花卉花期的人工调节 总被引:1,自引:0,他引:1
本文从温度,光照的长短,植物生长物质的影响,水肥管理状况,以及修剪、嫁接等技术措施,对花卉花期的调节控制技术,进行了论述。 相似文献
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105.
Wei Jiang Tongfei Shi Shichun Jiang Lijia An Donghang Yan Bingzheng Jiang 《Macromolecular theory and simulations》2001,10(8):750-755
The phase behavior of A–B-random copolymer/C-homopolymer blends with special interaction was studied by a Monte Carlo simulation in two dimensions. The interaction between segment A and segment C was repulsive, whereas it was attractive between segment B and segment C. The simulation results showed that the blend became two large co-continuous phase domains at lower segment-B component compositions, indicating that the blend showed spinodal decomposition. With an increase of the segment-B component, the miscibility between the copolymer and the polymer was gradually improved up to being miscible. In addition, it was found that segment B tended to move to the surface of the copolymer phase in the case of a lower component of segment B. On the other hand, it was observed that the average end-to-end distances (h) for both copolymer and polymer changed slowly with increasing segment-B component of the copolymer up to 40%, thereafter they increased considerably with increasing segment B component. Moreover, it was found that the h of the copolymer was obviously shorter than that of the homopolymer for the segment-B composition region from 0% to 80%. Finally, a phase diagram showing I phase and II phase regions under the condition of constant temperature is presented. 相似文献
106.
Hongsheng Wang Bingzheng Wang Sean-Thomas B. Lundin Hui Kong Bosheng Su Jian Wang 《Molecules (Basel, Switzerland)》2021,26(22)
To efficiently convert and utilize intermittent solar energy, a novel solar-driven ethanol steam reforming (ESR) system integrated with a membrane reactor is proposed. It has the potential to convert low-grade solar thermal energy into high energy level chemical energy. Driven by chemical potential, hydrogen permeation membranes (HPM) can separate the generated hydrogen and shift the ESR equilibrium forward to increase conversion and thermodynamic efficiency. The thermodynamic and environmental performances are analyzed via numerical simulation under a reaction temperature range of 100–400 °C with permeate pressures of 0.01–0.75 bar. The highest theoretical conversion rate is 98.3% at 100 °C and 0.01 bar, while the highest first-law efficiency, solar-to-fuel efficiency, and exergy efficiency are 82.3%, 45.3%, and 70.4% at 215 °C and 0.20 bar. The standard coal saving rate (SCSR) and carbon dioxide reduction rate (CDRR) are maximums of 101 g·m−2·h−1 and 247 g·m−2·h−1 at 200 °C and 0.20 bar with a hydrogen generation rate of 22.4 mol·m−2·h−1. This study illustrates the feasibility of solar-driven ESR integrated with a membrane reactor and distinguishes a novel approach for distributed hydrogen generation and solar energy utilization and upgradation. 相似文献
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108.
声学超材料及结构已被广泛研究,其超结构通常利用3D打印技术实现,当结构刚度较小或者面积较大时,由声固耦合所导致的声学效果与设计不符的情况广泛存在。本文针对含有膨胀腔类的超材料,研究了声固耦合对其声学性能的影响,采用有限元计算结合阻抗管实验的方法,得到其传递损失,分析了声固耦合现象对传递损失的影响。结果表明:薄壁膨胀腔结构的作用频率范围与只考虑声学理论计算的设计不符,声固耦合现象对传递损失产生显著影响;采用增加膨胀腔壁厚、减少膨胀腔内径或选择金属材料的方式,都可以使得声固耦合现象对传递损失的影响减小;仿真结果与实验结果基本吻合。该研究结果说明:对于膨胀腔类超材料,当刚度较小或者面积较大时,对其进行声固耦合分析是完全必要的。 相似文献
109.
中立型二阶非线性微分方程振动性的判据 总被引:7,自引:0,他引:7
Abstract. In this paper ,the oscillation criteria for the solutions of the nonlinear differential e-quations of neutral type of the forms: 相似文献
110.