定常流和振荡流共同作用下半浸没柱体水动力特性实验研究

顺应式的漂浮柔性圆柱型结构物,如深海养殖结构物的浮圈结构、波浪能发电装置的浮体部分等,大多是半浸没的。目前,学术界和工程界对半浸没圆柱的水动力特性了解较少,也使这些新型结构物在设计和分析时面临着载荷输入不确定性的难题。本文通过定常流和振荡流共同作用下半浸没柱体模型实验,开展半浸没柱体水动力载荷特性研究。实验中,由拖车带动半浸没柱体向前运动模拟等效定常流场,强迫柱体以不同振幅和周期振荡来模拟等效振荡流场。实验结果表明,在来流作用下半浸没柱体不可避免会遭受显著的平均升力作用,远大于其所受阻力载荷。研究揭示了水动力系数与多敏感参数的影响关系,确证了KC数对水动力系数影响较弱,总傅汝德数是水动力系数的主控参数,初步建立了流致半浸没柱体水动力载荷系数模型。本文工作可为相关海洋结构物的设计提供有益的指导。

阿基米德原理及应用实验器

阿基米德原理及应用实验器杜金霞马双刚（天津市南开区教育技术装备管理站）耿永喜（河北任丘市华北石油技工学校附中）Ｊ２１８６阿基米德原理及应用实验器系结合“阿基米德原理”一节（见９年义务教育三年制初中物理第一册１４３页）的编写特点，针对学生学过“原理”易...

Effect of nozzle geometry on pressure drop in submerged gas injection

Submerged gas injection into liquid leads to complex multiphase flow, in which nozzle geometries are crucial important for the operational expenditure in terms of pressure drop. The influence of the nozzle geometry on pressure drop between nozzle inlet and outlet has been experimentally studied for different gas flow rates and bath depths. Nozzles with circular, gear-like and four-leaf cross-sectional shape have been studied. The results indicate that, besides the hydraulic diameter of the outlet, the orifice area and the perimeter of the nozzle tip also play significant roles. For the same superficial gas velocity, the average pressure drop from the four-leaf-shaped geometry is the least. The influence of bath depth was found negligible. A correlation for the modified Euler number considering the pressure drop is proposed depending on nozzle geometric parameter and on the modified Froude number with the hydraulic diameter of the nozzle do as characteristic length.

TIB for Micropropagation and the Relationship between Anthocyanins and Chlorophyll of Strawberry Seedlings

In this study, we employed a temporary immersion bioreactor(TIB)system for the micropropagation of strawberry seedlings. The TIB method and the conventional method for the micropropagation of strawberry seedlings were compared in terms of explant propagation coefficient, seedling fresh weight,contents of anthocyanins and chlorophyll, and photosynthetic characteristics. The results showed that an inoculation density of 40 explants/L was suitable for the micropropagation of ’Benihope’ strawberry seedlings in the TIB. The propagation coefficient, fresh weight, photosynthetic rate, stomatal conductance, transpiration coefficient, and the contents of total anthocyanins and chlorophyll of seedlings micropropagated in the TIB were significantly higher than those of the seedlings micropropagated by the conventional method. In conclusion, the TIB method was superior to the conventional method in the micropropagation of strawberry seedlings.The negative reciprocity did not occur between anthocyanins and chlorophyll in strawberry seedlings cultured under forced ventilation such as TIB.

Surface modification of indium tin oxide by oxygen plasma immersion ion implantation

Organic electroluminescent device,also known as organic light-emitting diode (OLED),is a kind of solid state light emitting device by carrier injection which can directly transform electrical energy into luminous energy.Due to its low operating voltage,low energy consumption,high brightness,flexibility in the choice of materials and easy realization of full color display,OLED is the potential material both in the display and illumination fields.However,there is much scope to improve the efficiency,lifetime,and reduce the cost in mass production before OLEDs can replace traditional technology in some application fields.In this work,we report the oxygen plasma immersion ion implantation (PIII) to improve the surface oxygen ratio of ITO films for further increase of surface work function above the common treatment of O2 inductively coupled plasma (ICP).The ratio of oxygen content at the surface layer was improved to be much higher than by O2 ICP treatment.A further surface work function relative increase of 0.4e V above OICP sample and 0.4 eV above the as-prepared sample can be estimated by the peak relative shift in the X-ray photoelectron spectroscopy (XPS) diagram.Moreover,the XPS characterization was carried out at least 50 h after the PIII implantation to indicate that the surface modifying effects are stable.The variations of transparency and conductivity of the PIII treated ITO samples can be neglected.

Formaldehyde gas sensor based on TiO_2 thin membrane integrated with nano silicon structure

An innovative formaldehyde gas sensor based on thin membrane type metal oxide of Ti O2 layer was designed and fabricated. This sensor under ultraviolet(UV) light emitting diode(LED) illumination exhibits a higher response to formaldehyde than that without UV illumination at low temperature. The sensitivities of the sensor under steady working condition were calculated for different gas concentrations. The sensitivity to formaldehyde of 7.14 mg/m^3 is about 15.91 under UV illumination with response time of 580 s and recovery time of 500 s. The device was fabricated through micro-electro-mechanical system(MEMS) processing technology. First, plasma immersion ion implantation(PIII) was adopted to form black polysilicon, then a nanoscale TiO_2 membrane with thickness of 53 nm was deposited by DC reactive magnetron sputtering to obtain the sensing layer. By such fabrication approaches, the nanoscale polysilicon presents continuous rough surface with thickness of 50 nm, which could improve the porosity of the sensing membrane. The fabrication process can be mass-produced for the MEMS process compatibility.