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竹类植物茎秆液流研究:方法、特征及影响因素
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作者 汤志颖 高俊宏 +2 位作者 曾赞青 王淼淼 漆良华 《林业科学》 EI CAS CSCD 北大核心 2022年第9期157-164,共8页
根据竹类植物独特的生物学特性与解剖构造,选择适宜的茎秆液流测定方法,揭示茎秆液流的动态变化和影响因素,有利于深入阐明其生理生态过程与机制,为竹林水分养分精准管理、高效利用及生态经营提供科学依据。竹类植物茎秆液流的测量方法... 根据竹类植物独特的生物学特性与解剖构造,选择适宜的茎秆液流测定方法,揭示茎秆液流的动态变化和影响因素,有利于深入阐明其生理生态过程与机制,为竹林水分养分精准管理、高效利用及生态经营提供科学依据。竹类植物茎秆液流的测量方法起源于木本植物,包括热脉冲法、热消散探针法和茎热平衡法。其中,热脉冲法不受地形等环境条件的限制,但在低蒸腾状态下液流测定结果具有不确定性;热消散探针法成本相对较低,但传感器易因液流密度分布不均形成的径向梯度而引起测度误差,需要进行验证和校准;茎热平衡法无需探针钻孔,仪器包裹竹秆后可实时获取数据,但需满足流动条件稳定和温度恒定的基本假设条件。通常将3种测定方法结合应用并相互验证,从而获取较可靠的液流测定结果。竹类植物的茎秆液流具有相对普遍的规律,日变化、夜间动态和季节尺度上均表现为相似的“峰”状曲线特征。竹类植物日间液流于清晨启动,随后不断增加,至午后达到峰值,然后持续减少,入夜后达最低值;晴朗天气液流变化总体呈现“单峰”状曲线,阴雨天气呈现“多峰”状态。夜间液流总体保持低流量特征,在不同季节和环境条件下都显著低于日间液流,且变化幅度很小。季节尺度上液流量春季最低,夏末初秋最高,由冬季到夏季,液流开始上升和峰值达到的时刻均逐渐提前,由夏季到冬季则反之。不同生长阶段竹类植物液流特征也存在差异。竹类植物液流变化的影响因素包括不同于木本植物的生理解剖结构以及环境因子。其中,竹类植物中空的茎秆和地下鞭根系统是影响液流的生物学基础。环境因素通过影响蒸腾和植物根压而对液流产生影响,气温、饱和水汽压差和太阳辐射与茎秆液流的变化均具有很强的相关性。热扩散法探针的长度、测量的具体部位等测量方法差异也会导致不同测量结果。对未来竹类植物茎秆液流的测定和研究提出展望:理论上需探究其作用机理与影响机制,构建统计与验证模型;技术上应整合改进现有测定方法,研发适宜的测定方法与技术,提高测定精度;在应用上,应结合区域、气候、地形条件及竹种等差异设置参数,形成具有普遍性的测定模式。 展开更多
关键词 竹类植物 茎秆液流 热技术方法 特征 影响因素
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Study on the automatic process of line heating for pillow shape plate 被引量:3
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作者 WANG Ji LIU Yu-jun JI Zhuo-shang DENG Yan-ping GUO Pei-jun ZHOU Bo 《Journal of Marine Science and Application》 2006年第1期31-38,共8页
This paper focuses on the process for pillow shape plate by line heating technique, which is widely applied in the production of ship hull. Based on the analysis of primary parameters and experimental data in line hea... This paper focuses on the process for pillow shape plate by line heating technique, which is widely applied in the production of ship hull. Based on the analysis of primary parameters and experimental data in line heating process, the amount of local contraction generated by line heating has been illustrated. Then, combining with the computational result of local deformation determined by shell plate development, an optimization method for line heating parameters has been studied. This prediction system may provide rational arrangements of heating lines and technical parameters of process. By integrating the prediction system into the line heating robot for pillow shape plate, the automatic process of line heating for pillow shape plate can be achieved. 展开更多
关键词 line heating pillow shape plate prediction method automatic process
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Thermal conductivity of dielectric nanowires with different cross-section shapes 被引量:1
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作者 顾骁坤 曹炳阳 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第12期3777-3782,共6页
Non-equilibrium molecular dynamics simulations have been performed to investigate the effect of the cross-section shape on the thermal conductivity of argon nanowires. Some typical cross-section shapes, such as triang... Non-equilibrium molecular dynamics simulations have been performed to investigate the effect of the cross-section shape on the thermal conductivity of argon nanowires. Some typical cross-section shapes, such as triangle, square, pentagon, hexagon and circle, axe carefully explored. The simulation results show that with the same cross-sectional area of the regular polygons, tim thermal conductivities decrease with the reduction of the sides of the polygons, and the thermal conductivity of the circular nanowire is larger than those of the other polygonal ones. Phonon gas kinetic theory is used to analyse the phonon transport in nanowires, and the concept of equivalent diameter is proposed to illustrate the characteristic dimension of the none-circulax cross-section. 展开更多
关键词 thermal conductivity NANOWIRE phonon kinetic theory molecular dynamics
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Solar Heater Technologies Selection Using Multi-criteria Analysis
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作者 Mohsine Bouya Badr Abou El Majd +1 位作者 Merieme Agdid Abdellatif Ben Abdellah 《Journal of Energy and Power Engineering》 2015年第4期393-398,共6页
Regarding sun's potential in Middle East and North Africa zone and particularly in Morocco, we focus our work on the development of the knowledge and information concerning the solar heaters for domestic applications... Regarding sun's potential in Middle East and North Africa zone and particularly in Morocco, we focus our work on the development of the knowledge and information concerning the solar heaters for domestic applications, in order to help the industrial and the consumer to select an adaptive technology. As a result, a Moroccan mapping of solar water heating systems is presented in this work. This mapping concerns two technologies commonly used: the FPC (flat plate collectors) and the ETC (evacuated tubes ones). It is based on three criteria: firstly, the efficiency of the STC (solar thermal collectors); secondly, the economic aspect and at last, the reliability requirements. Based on these information, the multi-criteria outranking methodology PROMETHEE (preference ranking organization method for the enrichment evaluations) allows us to define an adequate solar heater technology linked with the climatic zoning of Morocco. 展开更多
关键词 MAPPING solar water heating flat plate collector evacuated tubes collectors PROMETHEE.
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