宁夏大坝发电有限责任公司I期给水泵出口最小流量阀控制在DCS中的实现

针对宁夏大坝发电有限责任公司I期给水系统三台给水泵最小流量阀原控制回路不可靠问题进行分析,将其引入DCS系统,并对其控制逻辑进行进一步完善,有效地提高了机组的安全稳定运行的能力。     

Fluid flow and heat transfer with nail dipping method in mould during continuous casting process

ABSTRACT

The character and cause of sliver defect on IF steel sheet surface are studied by means of SEM, unstable flow in mould could induce surface velocity and level fluctuations, leading to surface defects during continuous casting of steel. The nozzle clogging is a serious problem during the continuous casting of steel, due to its influence on the casting operations and products quality. In this study, the nail dipping method for measuring surface velocity and flow direction in molten steel were employed. The fluid flow in mould of whole casting sequence was investigated, especially during the nozzle clogging conditions. The results showed that when nozzle clogging occurred in the 7th heat, the flow velocities on R and L side of nozzle were 0.280 and 0.402?m/s, respectively. The surface defect ratio of hot-rolled and cold-rolled plates increases with the increase of heat flux deviation on both sides of the mould copper. The different clogging per cent on both sides of the nozzle will lead to asymmetry flow, the surface velocity is higher with the small clogging per cent side compared to that of relatively large per cent clogging side.     

用于SIS系统的限流孔板的设计和计算

安全阀作为石化行业中一种非常重要的独立物理保护层,流量控制是安全阀可靠性的重要指标。介绍了安全仪表系统(SIS)中用于安全阀前限制流量的4种方法,以及结合安全阀的设计流程。着重介绍了采用限流孔板作为限流元件,并对其计算、技术规格作了详细的描述。以限流孔板为例,分别对蒸汽、液体和气体进行了计算示例。     

Design of data feature-driven 1D/2D convolutional neural networks classifier for recycling black plastic wastes through laser spectroscopy

In this study, two types of convolutional neural network (CNN) classifiers are designed to handle the problem of classifying black plastic wastes. In particular, the black plastic wastes have the property of absorbing laser light coming from spectrometer. Therefore, the classification of black plastic wastes remains still a challenging problem compared to classifying other colored plastic wastes using existing spectroscopy (i.e., NIR). When it comes the classification problem of black plastic wastes, effective classification techniques by the laser spectroscopy of Fourier Transform-Infrared Radiation (FT-IR) with Attenuated Total Reflectance (ATR) and Raman to analyze the classification problem of black plastic wastes are introduced. Due to the strong ability of extracting spatial features and remarkable performance in image classification, 1D and 2D CNN through data features are designed as classifiers. The technique of chemical peak points selection is considered to reduce data redundancy. Furthermore, through the selection of data features based on the extracted 1D data with peak points is introduced. Experimental results demonstrate that 2DCNN classifier designed with the help of 2D data feature selection as well as 1DCNN classifier shows the best performance compared with other reported methods for classifying black plastic wastes.     

Numerical study of the MHD flow characteristics in a three-surface-multi-layered channel with different inlet conditions

A 3D MHD flow simulation was conducted to clarify the effects of the inlet flow conditions on the results of the validation experiment carried out previously and on the design window of the first wall using a three-surface-multi-layered channel. MHD pressure drop was largely influenced by the inlet condition. The numerical model with turbulent velocity profile showed qualitatively good agreement with the experimental result. The first wall temperature and pressure distributions obtained by the 3D simulation corresponded well to those obtained by the 2D simulation assuming fully developed flow. This suggested that complicated three-dimensional inlet flow condition generated in the L-shape elbow would not affects the existing design window.     

The behavior of statically-indeterminate structural members and frames with cracks present

Crack stability is discussed as affected by their presence in statically-indeterminate beams, frames, rings, etc. loaded into the plastic range. The stability of a crack in a section, which has become plastic, is analyzed with the remainder of the structure elastic and with subsequent additional plastic hinges occurring. The reduction of energy absorption characteristics for large deformations is also discussed. The methods of elastic-plastic tearing instability are incorporated to show that in many cases the fully plastic collapse mechanism must occur for complete failure.     

Fully developed thermal behaviors for parallel flow microchannel heat exchanger

The hydrodynamics and thermal behaviors of the flow in micro-heat exchanger parallel-plate are investigated numerically. The model that combines both the continuum approach and the possibility of slip at the boundary is adopted in the study. Effects of different parameters, such as, Knudsen number (Kn), heat capacity ratio (Cr), the effectiveness (e) and number of transfer units (NTU) are investigated. It is found that both the velocity slip and the temperature jump at the walls increase with increasing Kn. On the other hand, at low values of Kn, the NTU increases with increasing Cr, but at high values of Kn the NTU decreases with increasing Cr. With regard to the effect of Cr on e, it is found that increasing Cr leads to a reduction in e and for all Kn.     

基于Android平台的公文流转系统设计与实现

公文流转系统是办公自动化系统的重要组成部分,对改革办公模式、提高办公效率、实现无纸化办公起到至关重要的作用。本文在研究和分析当前公文流转系统的基础上,采用Android平台、SSH框架、MVC模式和POI WORD等关键技术,阐述了系统的设计过程,对结构设计、数据库设计、公文的保存和公文流转流程的实现等关键问题进行了详细讨论。开发出了功能齐全、高效快捷的公文流转系统。     

Nanoindentation characterised plastic deformation of a Al0.5CoCrFeNi high entropy alloy

Abstract

The plastic deformation of a high entropy alloy Al_0.5CoCrFeNi was investigated by instrumented nanoindentation over a broad range of strain rates at room temperature. Results show that the creep behaviour depends on the strain rate remarkably. In situ scanning images showed a significant pile up around the indents, demonstrating that a highly localised plastic deformation occurred in the process of nanoindentation. Under different strain rates, contact stiffness and elastic modulus basically remain unchanged. However, the hardness decreases as indentation depth increases due to indentation size effect. For the same maximum load, serrations became less prominent as the loading rate of indentation increased. Similar serrations have been observed in the current alloy upon quasi-static compression.