凌庄子水厂保水堰流量系数试验

凌庄子水厂蓄水池进水口处有一保水堰,为非标准薄壁堰,不能使用已有堰流公式对其过流量进行准确计算。为了得出较为精确的过流流量,按照重力相似准则制作几何比尺为1∶5的模型进行试验研究。在已有自由出流公式的基础上,对自由出流流量系数进行修正并对淹没情况下流量变化过程进行研究。对该非标准堰自由出流流量系数的实测值与经验值进行分析比较,发现堰板槽降低了实际自由出流过流能力。淹没出流的流量系数主要与下游尾水位有关,试验中形成的淹没式堰流受实际堰型尺寸影响,下游尾水位和堰上水位近似相等,不完全适用已有淹没出流流量公式,通过试验给出了修正淹没系数随h/p的变化关系。结果表明利用堰前、堰后水位初步计算过流流量是可行的,可为该工程提供参考,也可为实际工程中非标准矩形堰的流量计算提供思路。     

A mini review on two-dimensional nanomaterial assembly

Two-dimensional (2D) nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004, due to their intriguing physicochemical properties and wide-ranging applications in catalysis, energy-related devices, electronics and optoelectronics. To maximize the potential of 2D nanomaterials for their technological applications, controlled assembly of 2D nanobulding blocks into integrated systems is critically needed. This mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures, from in-situ assembly method to post-synthesis assembly. The applications of 2D assembled integrated structures are also covered, especially in the areas of energy, electronics and sensing, and we conclude with discussion on the remaining challenges and potential directions in this emerging field.

     

土木工程施工课程线上平台教学实践

土木工程施工课程作为土木工程及工程管理专业的学科基础课和核心专业课程,在疫情防控期间"停课不停教""停课不停学"的要求下,通过线上平台进行授课。由于土木工程施工课程内容庞杂、综合性强、实践性强,且章节之间关联性较弱,探究既能使学生快速适应,又能保证教学质量的在线教学方法至关重要。以华南某高校土木工程施工课程为例,基于中国大学MOOC、建筑云课、腾讯课堂、QQ群等线上平台讲授教学内容,并运用问卷调查对课程线上教学效果进行评价。结果表明,线上教学为学生提供了丰富灵活的学习方式,显著提高了学生的自主学习能力,扩大了学生的知识面,达到了较好的学习效果。     

Study on wax precipitation characteristics of wax deposit in pipes

Wax deposit properties are a significant concern in pipeline pigging during waxy crude oil transportation. In the present work, the impacts of flow conditions and oil properties on the wax precipitation characteristics of wax deposits are investigated. A flow loop apparatus was developed to conduct wax deposition experiments using four crude oils collected from different field pipes. The differential scanning calorimetry (DSC) technique was employed to observe the wax precipitation characteristics of crude oil and wax deposit. The results show that the wax content and the wax appearance temperature (WAT) of the deposits increase with shear stress and radial temperature gradient, and decrease with radial wax molecule concentration gradient near the pipe wall. The DSC tests on the wax deposits revealed that the deposit wax content is strongly correlated to the oil wax content. Furthermore, an empirical correlation was developed to predict the wax content and the WAT of the wax deposit. Verification of the empirical correlation using the different oils indicated that the average relative error of the wax content prediction and average absolute error of WAT prediction were 13.2% and 3.6°C, respectively.     

套管固井质量问题及对策分析

从油田现场反应的情况出发，对调整井固井，尾管固井，大位移井套管固井和其他固井的质量问题进行了分析，针对各种问题产生的原因，提出了相应换解决办法。     

浅谈集成电路的废气处理

集成电路的工业废气有含氟化物、硫酸雾的酸性废气,含氨的碱性废气,含异丙醇、光刻胶的有机废气,含SiO_2的含尘废气,以及含硅烷、磷烷的工艺尾气等,这些工业废气中大部分成分是有毒有害的,必须进行有效的处理才能排入大气中。主要讨论上述工业废气的分类、处理方式、应用范围及应用实例等。     

污水处理厂尾水排放对圩区河道水环境影响预测

以芜湖市长江沿线澛港圩区内污水处理厂尾水排放为例,充分考虑圩区内水利工程的调度规则、受纳水体的环境保护目标、污水处理厂运行工况等因素制定预测方案,分别采用一维稳态数学模型和二维水量水质数学模型对内河和外河的影响进行预测,根据预测结果提出了对受纳水体影响最小的排放方案,为决策部门提供了科学依据.     

Poisson Shot Noise Removal by an Oracular Non-Local Algorithm

Journal of Mathematical Imaging and Vision - In this paper, we address the problem of denoising images obtained under low-light conditions for the Poisson shot noise model. Under such conditions,...     

有理分式反Z变换的实用方法

本文给出的有理分式反Z变换方法可以同时给出因果和逆因果两种序列.由于它避免了现有三种反Z变换方法所必需的确定分式极点的困难及误差,所以使用起来较为方便和精确.它可用来研究子波信号的延迟性质与系统(如滤波器)稳定性和可逆性,还可用来求解线性系统的差分方程,确定分式零点与极点的定位范围.     

ZL105合金悬浮铸造工艺研究

对ZL105合金悬浮剂的制备、加入量、加入方式、加入温度及熔化时间等悬浮铸造工艺进行了初步探讨。结果表明,ZL105合金采用恳浮铸造简单易行,而且对减小体收缩、细化晶粒组织、降低壁厚对晶粒组织的敏感性以及提高针孔度级别有明显效果。