为提升太阳能热气流发电系统输出功率,对烟囱底部导流体的不同形状进行研究。基于等效速度理论,提出一种新型等效速度面划分方式,以此计算输出功率。通过数值模拟研究不同形状导流体对烟囱内部速度场和压力场的影响,将透平装置截面处依据模拟结果划分为高速区和低速区,并通过实验对模拟结果进行验证。结果表明:导流体形状不同,烟囱内部的速度场和压力场变化显著。高速区内圆台导流体对等效速度及输出功率的提升优于其他形状的导流体,且烟囱底部负压增幅最大,提升效果明显,模拟结果与实验具有较高的吻合度。
与一般推荐系统不同,由于儿童无法准确表述自己的阅读兴趣,儿童绘本推荐系统会出现特殊的冷启动问题。针对这个问题,提出一种基于隐式问询的个性化推荐技术,通过隐式询问儿童更容易回答的日常行为喜好,来推断儿童潜在的阅读喜好,提高推荐系统的准确率。首先,借助专家信息设计符合儿童日常行为的隐式问询题目;然后,建立隐式问询儿童兴趣模型,并计算出儿童的阅读兴趣;最后,生成绘本推荐列表。在全国连锁企业老约翰绘本馆和皮克布克绘本王国提供的真实数据集上进行了相关对比实验,实验结果表明,该隐式问询推荐技术有更高的准确度,能有效缓
Metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen generation.Currently,their stability in water is a vital and urgent res
为了避免以往用酸碱刻蚀模板法制备空心二氧化硅纳米颗粒带来的安全和环保问题,提出一种高效绿色合成方法。以聚苯乙烯为模板,先将SiO2沉积在模板上,再通过煅烧去除PS模板,制备了空心二氧化硅纳米颗粒,并通过扫描电镜、透射电镜、X射线能谱分析仪、傅里叶变换红外光谱仪、X射线衍射仪、热重分析仪和物理吸附仪等对其结构进行表征。结果表明:所制备的空心二氧化硅纳米颗粒具有明显的空心结构,颗粒直径约为120 nm;组成元素为Si和O;在20~780℃环境下,空心二氧化硅纳米颗粒都具有优异的热稳定性;
Pillaring technologies have been considered as an effective way to improve lithium storage performance of Ti3C2Tx MXene.Nevertheless,the pillared hybrids suffer
Two-dimensional (2D) materials hold great promise for applications in optoelectronics,quantum information science,and energy conversion due to their remarkable
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The application of polymers to replace oleylamine (OLA) and oleic acid (CA) as ligands for perovskite nanocrystals is an effective strategy to improve their sta
Lead telluride (PbTe) is one of the reliable candidates for infrared (IR) optoelectronics with optimum band-gap as well as excellent photoelectric properties.Gr
The development of magnetic two-dimensional (2D) materials in its infancy has generated an enormous amount of attention as it offers an ideal platform for the e