矿井水泵并联运行流量增量的影响因素与相关问题的探讨

分析了水泵并联运行时水泵特性曲线与管路阻抗对流量增量的影响,以及并联可能出现的流量变化与超载问题,阐述了不同水泵并联运行时小水泵流量可能出现的变化趋势。     

黄栀子花期气象预报方法研究

为研究黄栀子开花规律,预测黄栀子开花时间,利用2007—2020年江西天顺生态农业有限公司黄栀子物候观测资料与同期气象观测数据,采用Origin拟合方法,对黄栀子花期与气象因子进行相关分析,并建立黄栀子花期预报模型.结果表明:黄栀子平均始花期为5月16日,盛花期为5月20日;黄栀子花期主要受气温、日照、降水影响较大,与上年度11月上旬,4月上旬至5月上旬平均最高最低气温、4-5月上旬日照及降水相关性最显著.据此建立的预报模型预测最大误差在2d以内,为开展黄栀子花赏花旅游项目提供了决策依据.     

Super-hydrophobic and Self-cleaning PVDF Film Fabricated by Chemical Bath Deposition

Self-cleaning surfaces have received a great deal of attention recently,both in theoretical studies and commercial applications.The self-cleaning surface of lotus leaf is hydrophobic and rough,showing a micro-and nano-scale morphology.The micro-reliefs of lotus leaf were mimicked using polyvinylidene fluoride(PVDF)film and nano-scale peaks on the top of the micro-reliefs were implemented by the reaction between methyltrichlorosilane and the reactive groups of PVDF film treated by oxygen plasma.A lotus-leaf-like surface of the PVDF film was clearly observed by scanning electronic microscopy(SEM)and atomic force microscope(AFM).Elemental composition analysis by X-ray photoelectron spectroscopy(XPS)revealed that the material of the nanostructure of PVDF film was polymethylsiloxane.The superhydrophobic property of the mimicked self-cleaning surface was validated by the water contact angle and sliding angle on the lotus-leaf-like PVDF film,which were 156.6° and 4°,respectively.In this case,water droplets can easily move across the PVDF film surface,carrying dirt particles away,leaving no contamination.