220kV母线倒闸过程隐患分析及改进建议

随着当今电力行业的不断发展,220 kV母线也得到了广泛应用。而在220 kV母线的倒闸过程中,母联断路器、隔离刀闸、辅助触点等都属于危险点,一旦操作出现问题,便会预留诸多的安全隐患。基于此,对220 kV母线倒闸过程中的隐患进行分析,并针对这些隐患提出了相应的改进建议,避免误操作情况所导致的不利影响。

新疆克孜尔水库主坝渗流监测资料分析

为研究新疆克孜尔水库除险加固后主坝的渗流情况,运用数理统计方法对主坝渗流监测资料进行了过程线分析、水平渗透坡降分析、相关性分析、位势及测压管水位滞后时间分析。研究结果表明:(1)主坝渗流量较小,心墙防渗效果较好;(2)下游无渗透明流,无积水,无异常变形,渗流状况基本稳定,大坝运行工况基本正常;(3)0+252监测断面下游位势略微偏高,判断该断面心墙与坝基的帷幕灌浆局部风化或排水花管排水不畅,应引起重视。

Distribution of mineral species in different coal seams of Talcher coalfield and its transformation behavior at varying temperatures

Mineral phase characterization and thorough understanding of its transformation behavior during combustion are imperative to know the potential utilization of coal in the thermal industries. The primary objective of this work is to analyze the quality of Indian Coals and obtain their mineral species-specific information at different depths. The samples were obtained from Talcher Coalfield, Odisha, India. Coal from four seam sections in the Talcher coalfield, India are mainly high ash coal （〉50 %） and volatile matter deceases along with the seam depth. XRD results show that the major mineral phases present in the coal are quartz and kaolinite. Siderite, illite, and anatase were found in minor quantities. It has been observed that the clay minerals （kaolinite, silimanite, illite） decompose at higher temperature and traces of dolomite, mullite, hematite etc. are formed during the process of combustion. Among the four seams （M2, M12, M24 and M43） studied, ash of M43 has high A1203%, TIO2% and K20% content and low SIO2%, CaO% and MgO% content. High acid- to-base ratios contributed to high ash fusion temperatures （IDT 〉 1500 ℃） and low slagging potential of the coals studied. Relatively low fouling index （〈0.3） was estimated for all the coal seams studied. Furthermore, thermodynamic modeling software, FactSage, have been used to envision the mineral phase transformations that take place between 800 and 1500℃ during coal combustion.

Nonlinear Statistical Process Monitoring and Fault Detection Using Kernel ICA

A novel nonlinear process monitoring and fault detection method based on kernel independent component analysis(ICA) is proposed.The kernel ICA method is a two-phase algorithm:whitened kernel principal component(KPCA) plus ICA.KPCA spheres data and makes the data structure become as linearly separable as possible by virtue of an implicit nonlinear mapping determined by kernel.ICA seeks the projection directions in the KPCA whitened space,making the distribution of the projected data as non-gaussian as possible.The application to the fluid catalytic cracking unit(FCCU) simulated process indicates that the proposed process monitoring method based on kernel ICA can effectively capture the nonlinear relationship in process variables.Its performance significantly outperforms monitoring method based on ICA or KPCA.

Subsea rigid jumper design and VIV fatigue evaluation

The purpose of this paper is to present a design procedure for subsea rigid jumper system including strength and fatigue analysis. Special attention gives to a methodology based on DNV-RP-F105 to evaluate jumper fatigue damage caused by vortex induced vibration (VIV). Jumper strength analysis is to determine the jumper con-figuration which can accommodate various load conditions and all possible span lengths driven by installation tole-rances of connected subsea structures. Fatigue analysis includes two parts:thermal fatigue and VIV fatigue. This paper presents the procedure of VIV fatigue damage calculation. An example is given to illustrate above methodologies.

Installation Strength Analysis of Subsea Flowline Jumpers

A subsea flowline jumper （FJ） is a basic connected component for the wet oil tree, subsea pipeline and riser base, and it plays an irreplaceable role in the subsea production system. During the installation of FJ, collisions often happen between FJ and other equipment, which may cause serious damage. Besides, as the operating water depth increases, the demand for the installation equipments, such as the crane and winch, will increase. The research of deepwater FJ installation in China is still in the primary stage, thus an installation method for the deepwater FJ is proposed in this paper. Finite element models of a typical M-shaped FJ installation system are built to simulate the installation procedures. Analysis results show that the installation steps designed are feasible and valid for the deepwater FJ. In order to ensure the safety of the installation process, the collision-sensitive analysis for the FJ is conducted, and results show that it is necessary to set the pick up speed at a proper value, in order to avoid collision in the installation process. Besides, the mechanical characteristics of FJ during the installation are investigated under a range of environmental conditions and it is found that the maximum stress of the FJ always happens at its central position. The basic requirements for the installation equipment are also obtained through the analysis of the main installation steps.

Prediction of cavity growth rate during underground coal gasification using multiple regression analysis

During underground coal gasification （UCG）, whereby coal is converted to syngas in situ, a cavity is formed in the coal seam. The cavity growth rate （CGR） or the moving rate of the gasification face is affected by controllable （operation pressure, gasification time, geometry of UCG panel） and uncontrollable （coal seam properties） factors. The CGR is usually predicted by mathematical models and laboratory experiments, which are time consuming, cumbersome and expensive. In this paper, a new simple model for CGR is developed using non-linear regression analysis, based on data from 1 l UCG field trials. The empirical model compares satisfactorily with Perkins model and can reliably predict CGR.

Computational analysis of linear friction welding process and micromechanical modeling of deformation behavior for medium carbon steel

Finite element simulation of linear friction welding(LFW) medium carbon steel was carried out using the ABAQUS software. A two-dimensional(2D) coupled thermo-mechanical model was established. First, the temperature fields of medium carbon steel during LFW process were investigated. And then, the Mises stress and the 1st, 2nd and 3rd principal stresses fields' evolution of the steel during LFW process were studied. The deformation behavior of LFW carbon steel was analyzed by using micromechanics model based on ABAQUS with Python code. The Lode parameter was expressed using the Mohr stress circle and it was investigated in detail.

Deformation Analysis Due to Early Loading of Concrete Buildings

The building industry has experienced in recent years a strong growth in demand in general and in the case of reinforced concrete buildings this increase has been more marked. This fact has also contributed to accelerate all stages of the production process of these constructions with more pronounced effects on the methodologies used in the constructive steps that influence directly the structural design of the building. Structures loaded at ever earlier ages, in which the strength and deformation properties of materials are not yet sufficiently mature. It is a variable that needs to be taken into account already in the design phase so that the concrete structure behaves within acceptable level of reliability taking into account design code recommendations for service life. To understand the importance of constructive effects and to assess its magnitude in the execution of reinforced concrete buildings, this paper presents result from nonlinear analyses using finite element method adopting an approach commonly referred as staged construction applied to a typical building found in the practice. The effects of creep and shrinkage were considered and the results obtained demonstrate that the strains due to constructive effects can, in certain cases, assume representative values which, if ignored, can lead to important pathologies in the building.

The influence of steel slag on the hydration of cement during the hydration process of complex binder

The influence of steel slag,a by-product from the processing of iron to steel,on the hydration of cement during the hydration process of complex binder was studied by calorimetry,X-ray diffraction analysis,and Ca(OH)2 content determination.The results show that steel slag and cement affect each other’s hydration by changing the hydration environment.Steel slag does not react with the hydration products of cement.The dormant period of cement-steel slag complex binder during the hydration is longer than that of cement.The more the adding amount of steel slag is,the longer the dormant period of complex binder will be.The steel slag decreases the early hydration rate of cement.This phenomenon is more obvious with the increment of steel slag addition.However,the steel slag can promote the hydration degree of cement at later ages and the promoting effect becomes more obvious with the increment of steel slag addition and the hydration ages.