Showing papers in "Journal of Xi'an University of Technology in 2000"

Correlation Method of Water Quality and Quantity and Its Application to Load Estimation of Nonpoint Source Pollution

Abstract: Rainfall runoff is the main factor affecting the formation of nonpoint pollution For this reason, the correlation relationship of water quality and quantity is established in accordance with the monitoring and measuring data The yearly runoff is divided into the surface runoff and the runoff in the dry season, and also, the correlation relationship of water quality and quantity is used for the surface runoff, whereby presenting the correlation method of water quality and quantity to estimate the yearly load of rainfall runoff pollution in the case of limited data The practical examples used in the studies indicate that this method is feasible and practical

Experimental Study of the Velocity of Bubble Rising in Water

Abstract: Aeration plays an important role in the treatment of activated sludge, nevertheless, the velocity of bubble rising in water is of critically effects upon the aeration. Through the experiment the moving pattern of bubble is studied, and the relationship between the velocity of bubble rising and the diameter of bubble is analysised.It is tested that there exists a maximum value of the bubble rising velocity when Renord number reaches 300 or so. This research can provide a scientific base for the treatment or disposal of activated sludges.

Analysis of 3-D Model of Coupled Seepage and Stress Fields in Fracture Network of Rock Mass

Abstract: Based on the characteristic of fluid flow through the fracture network of rock mass, the mechanical mechanism of coupled fluid flow and stress is analyzed The mathematical model for coupled analysis of the three dimensional seepage and stress fields in rock mass of fracture network is proposed The model considers both the normal seepage pressure and the tangent hauling force of the fracture flow Applying the mathematical model for the couple analysis, a computation example is also given to indicate the efficiency and applicability of the model

The Technique of Microarc Oxidation on Aluminum Alloy

Abstract: The present researches on microarc oxidation technique of aluminum alloy are introduced in this paper. The conditions and mechanisms of formation for Al 2O 3 ceramic coating on surface of aluminum alloy in electrical field by high pulse voltage of electrolyte at different times are described, and the possible applied fields of this technique is compared to those of other present surface treatment processes on aluminum alloy. The preparation methods of microarc oxidation coating and the influences of such factors as current, voltage, the kind of electrolytes on properties and structures of Al 2O 3 ceramic coating are summarized.

An Algorithm of Coupled Finite Element and Kalman Filtering for Optimal Design of Groundwater Regime Monitoring Network

Abstract: In this paper, an algorithm of coupled finite element and Kalman filtering is proposed based on the consideration of deterministic and stochastic behaviors of groundwater movement and is applied to optimal design of groundwater regime monitoring network in Daqing region. This algorithm is used to analyse the groundwater dynamic monitoring network in Daqing region. The results indicate that it is difficult to implement monitoring objective for existing groundwater regime monitoring network in Daqing region and its optimum groundwater monitoring network should consist of 88 observation wells with observation frequency of one time per month.

Water Flow Behaviors of Channel Bend in Middle Sized Radius and Big Bend Angle of Curvature

Abstract: In accordance with the experiments, the water flow behaviors of middle sized radius with great angle of curvature in water conservancy project is analyzed, the inter relationships and influences among the ratio (r 0/B) of mean radius r 0 and width B of channel bend and that of location θ 1 of first maximum wave on outer bend walls of channel, the r 0/B with the ratio(h 2/h 1) of water depthh 2of first maximum wave on outer bend walls of channel and water depth h 1 of approach of channel bend are studied, the limiting value of preventing the occurrence of dry bottom on inner bend walls of channel is provided, and the variation in the water pressure on outer bend walls of channel is tested, and the empirical formulas are presented for the wave angle β 1 and the minimum mean radius r 0min of channel bend in this paper.

The Density Damage Increment and Its Digital Image of Rock in Compression

Abstract: It is difficult to detect the absolute density of rock by CT image in quantitative analysis of rock damage process in compression. This paper presents a new concept concerning the density damage increment and deduces a quantitative relation formula between CT value and density damage increment, on the basis of which CT image is converted into density damage increment images. In compration with the traditional CT image analysis method based on the variation in gray scale, the advantages of the density damage increment image lie not only in the quantitative analysis of damage process of rock in compression but also in the definite physical sense of image itself.

Research on the Law of Porosity of Rock with Depth

Abstract: Porosity is an important parameter characteristized physical, mechanical and seepage properties of rock. In general, when seepage problem of rock is studied in shallow underground rock in natural condition, porosity of rock is taken as a constant. However, porosity of rock changes with depth, geostress and engineering forces. Through analysis of triaxial test of rock samples, it is discovered that there is a quartic polynomial relation between porosity of rock and depth and porosity of rock decreases with depth increase. Porosity of rock approximates to a constant under 6000 m～7000 m depths.

Modification to Kellicutt Formula

Abstract: 针对凯里卡特公式使用过程中, 计算值与测量值有较大偏差及纵横比对抗压强度的影响, 在箱高大于25cm的条件下, 提出了一个修正因子k. 引入修正因子k的凯里卡特公式不但反映了纵横比A的影响, 且经实验和资料数据验证, 修正后的公式比原公式的计算结果更符合实际测量结果. 对凯里卡特公式中英、公制转换常数不变的现象进行了纠正, 提出了一套公制条件下凯里卡特公式的使用常数.

The Physical Mechanism and Depreciation and Rational Burying Depth of Sand Layer in Loess

Abstract: Sand layer set in loess will play a part in water resistance and depreciation so as to make most of soil water retain in fine soil layer over sand layer. This is the bright measure suggested in recent years for water depreciation reduction and resistance in architectural construction. The physica physical mechanism of water resistance and depreciation of sand layer in loess is analysed from the physical angle and the view of soil energy, with the purpose to account for the behaviors of water resistance and depreciation of sand layer in loess theoretically. And at the same time, the optimal burying depth of sand layer in loess is analysed from the angle of infiltration proof in architecture; and the tactic distribution of soil water in surface layer is given in this paper.

The Model of Water Resources Sustainable Utilization and Its Application Research

Abstract: The paper analyzes objective parameter of water resources sustainable utilization systems and establishes water resources sustainable utilization multi objective analysis evaluated models, and puts forwards the thinking and method for a solution to the model with multi objective whereby laying a solid theoretical foundation for the quantitative study of water resources and economic system. The model and algorithm can be used to carry out the actual case study of sustainable utilization of water resources in Guanzhong region. Also, the satisfactory and coordinative scheme of water resources utilization and economic development at the different years of different levels in Guanzhong regions. The research achievements are of the reference and practical values to water resources and social economy and sustainable development of bioenvironment in the regions where there is shortage of water resources.

Behaviors of Air-Water Two-Phase Flow and Its Homogeneous Model

Abstract: This paper deals with the numerical simulation of aerated flow and analyses the behaviors of air water two phase flow in details in water conservancy works from an angle of establishing maths models. It has been proved theoretically that the homogeneous model is applicable to the ′dilute bubbly flow′ in water works and that the continuity equation and momentum equation of air water mixture can be replaced by those of water so as to simplify the problems. The homogeneous model is used to calculate the aerated flow in the plunge pool. The calculated aerated concentration values are found to be basically in agreement with the actually measured values, whereby indicating that this model can be used in numerical simulation in air water two phase flow in plunge pool.

A Study of the Optimal Method for the Exponential Smooth Parameters

Abstract: WT5,5”BZ]Based on the principle of statistics, this paper analyses the precision feature of exponential smoothing forecasting model. The optimal model of the smooth parameter extimation is established. A calculating algorithm of the optimal model is presented in this paper. The calculated results from the actual examples indicate that in comparison with the experimental algorithm, this optimal algorithm is of fast convergence speed and higher calculation accuracy.

Three Dimensional Seepage Model in Main Fracture Network of Rock Mass

Abstract: Seepage analysis is an important item for hydropower engineering. Much of seepage paths is fracture network in rock mass surrounding dam. It is difficult to solve this seepage problem in fracture network by using continuum model. In terms of seepage characteristic in fracture network of rock mass, three dimensional seepage model in main fracture network of rock mass is constructed. The finite element method in combination with calculation examples is used to analyse three dimensional seepage problems in main fracture network of dam foundation. The results of comparison of theoretical solution with finite element solution indicate that three dimensional seepage model in main fracture network of rock mass and the finite element numerical approach are effective and available.

Research on Reaeration Coefficient in Rivers

Abstract: The oxygen transfer theory cannot be used to predict the reaeration coefficient in rivers due to some undetermined parameters. Based on the two film theory as a starting point, this paper derives the expression of liquid film thickness ( δ ) from the angle of the turbulent structure. The actually determined data are used to fit the proportional coefficient among them whereby making the mass transfer theory model including the parameter δ be used in practice.