The influence of parameters pertaining to the confinant structure on water hammer had been less studied than those relative to the fluid. One of them is the inner pipe-diameter, a basic structural-parameter that makes...The influence of parameters pertaining to the confinant structure on water hammer had been less studied than those relative to the fluid. One of them is the inner pipe-diameter, a basic structural-parameter that makes its influence in essential hydraulic topics such as head loss, in pipelines. In this paper, the objective is to analyze the inner-diameter influence on water hammer phenomenon. An analytical algorithm for solving the unsteady-one-dimensional water hammer model had been applied. It had allowed estimating the instantaneous head at any point of a single pipeline. The model was solved by mean of the Laplace＇s Transformed application and the anti-transforming procedure into the complex field. To determinate the influence of internal-diameter conduit on the pressure oscillation, four distinct inside-diameter values were introduced into the solution, successively. The first overpressure-peak at each case was tabulated along with the corresponding inner^liameter and a mathematical relation had been founded. The obtained results show a close dependence between both, over-pressure peaks and internal-pipe diameter. It was founded that this dependence is given in terms of a non-linear relation between them. It was further founded that the wave frequency is sensitive to the variation of the pipe-diameter.展开更多
On the basis of ANSYS finite element model(FEM) software, the deep-level rockburst in Fuxin coalfield was simulated numerically. Based on Haizhou Mine and Wulong Mine as two typical deep-level rockburst examples in Fu...On the basis of ANSYS finite element model(FEM) software, the deep-level rockburst in Fuxin coalfield was simulated numerically. Based on Haizhou Mine and Wulong Mine as two typical deep-level rockburst examples in Fuxin coalfield, the rules and characteristics of the deep-level rockburst were analyzed. And the models were es- tablished. For Haizhou mine, the relationship between mining distance and rockburst was presented when 100, 300, 600 m were mined in 3313 working face. When 300 m were mined, the rockburst began to emerge. When 600 m were mined, the rockburst was the most possible to happen and the compression stress of the working face reached to the maximum value. The effect of tectonic stress on synclinal axis is also a key factor to rockburst occurrence. This was verified by the rockburst happened when 496 m were mined. For Wulong mine, based on the 311 working face as an example, the contours of Y stress in the roof and floor were obtained when the mining distance were 100, 200, 300 and 400 m. When 100 and 400 m were mined, the high stress con- centration regions occurred in the front of working face. This shows the rockburst is easy to happen. It is confirmed by the rockburst when 91m were mined in 311 working plane. The above indicates that the numerical simulation has instructive rule to study the deep-level rockburst in Fuxin coalfield.展开更多
The aim of this article is to analyse aggressive behaviour of pupils during school breaks. The main emphasis has been put on the importance of teachers＇ expectations concerning behaviour violating norms. The role of ...The aim of this article is to analyse aggressive behaviour of pupils during school breaks. The main emphasis has been put on the importance of teachers＇ expectations concerning behaviour violating norms. The role of these expectations as predictors of pro-social and anti-social behaviour has been analysed. The research is based on the assumption that every culture develops specific benchmarks in reference to which people judge various social phenomena. Creation of an individual conception of oneself and making a plan for one＇s life is based, to some extent, on social values which constitute the crucial element of every culture. The hypothesis to be verified in this study was the presence of a significant link between the occurrence of anti-social and pro-social behaviour and the adopted axiological assumptions concerning students and their behaviour. The subjects of the study were students and teachers from 18 schools representing three types of culture and three educational levels （primary, lower secondary, and upper secondary）. The total number of 1,212 students were observed （Goldsmith＇s Observational Questionnaire）, and 36 teachers were interviewed. The results indicate a link between the adopted school culture and teachers＇ functioning, and open perspectives of further research on the connection between the values in school curricula and the occurrence of behaviour violating social norms and bounds.展开更多
When a normal shock wave interacts with a boundary layer along a wall surface in supersonic internal flows and the shock is strong enough to separate the boundary layer, the shock is bifurcated and a series of shocks ...When a normal shock wave interacts with a boundary layer along a wall surface in supersonic internal flows and the shock is strong enough to separate the boundary layer, the shock is bifurcated and a series of shocks called “shock train” is formed. The flow is decelerated from supersonic to subsonic through the whole interaction region that is referred to as “pseudo-shock”. In the present paper some characteristics of the shock train and pseudo-shock and some examples of the pseudo-shocks in some flow devices are described.展开更多
In this paper,the reflection phenomenon of a vapor shock front(both sides of the front are in the vapor phase)in a van der Waals fluid is considered.Both the1-dimensional case and the multidimensional case are investi...In this paper,the reflection phenomenon of a vapor shock front(both sides of the front are in the vapor phase)in a van der Waals fluid is considered.Both the1-dimensional case and the multidimensional case are investigated.The authors find that under certain conditions,the reflected wave can be a single shock,or a single subsonic phase boundary,or one weak shock together with one subsonic phase boundary,which depends on the strength of the incident shock.This is different from the known result for the reflection of shock fronts in a gas dynamical system due to Chen in 1989.展开更多
文摘The influence of parameters pertaining to the confinant structure on water hammer had been less studied than those relative to the fluid. One of them is the inner pipe-diameter, a basic structural-parameter that makes its influence in essential hydraulic topics such as head loss, in pipelines. In this paper, the objective is to analyze the inner-diameter influence on water hammer phenomenon. An analytical algorithm for solving the unsteady-one-dimensional water hammer model had been applied. It had allowed estimating the instantaneous head at any point of a single pipeline. The model was solved by mean of the Laplace＇s Transformed application and the anti-transforming procedure into the complex field. To determinate the influence of internal-diameter conduit on the pressure oscillation, four distinct inside-diameter values were introduced into the solution, successively. The first overpressure-peak at each case was tabulated along with the corresponding inner^liameter and a mathematical relation had been founded. The obtained results show a close dependence between both, over-pressure peaks and internal-pipe diameter. It was founded that this dependence is given in terms of a non-linear relation between them. It was further founded that the wave frequency is sensitive to the variation of the pipe-diameter.
基金Supported by National Nature Science Foundation of China (50490275)
文摘On the basis of ANSYS finite element model(FEM) software, the deep-level rockburst in Fuxin coalfield was simulated numerically. Based on Haizhou Mine and Wulong Mine as two typical deep-level rockburst examples in Fuxin coalfield, the rules and characteristics of the deep-level rockburst were analyzed. And the models were es- tablished. For Haizhou mine, the relationship between mining distance and rockburst was presented when 100, 300, 600 m were mined in 3313 working face. When 300 m were mined, the rockburst began to emerge. When 600 m were mined, the rockburst was the most possible to happen and the compression stress of the working face reached to the maximum value. The effect of tectonic stress on synclinal axis is also a key factor to rockburst occurrence. This was verified by the rockburst happened when 496 m were mined. For Wulong mine, based on the 311 working face as an example, the contours of Y stress in the roof and floor were obtained when the mining distance were 100, 200, 300 and 400 m. When 100 and 400 m were mined, the high stress con- centration regions occurred in the front of working face. This shows the rockburst is easy to happen. It is confirmed by the rockburst when 91m were mined in 311 working plane. The above indicates that the numerical simulation has instructive rule to study the deep-level rockburst in Fuxin coalfield.
文摘The aim of this article is to analyse aggressive behaviour of pupils during school breaks. The main emphasis has been put on the importance of teachers＇ expectations concerning behaviour violating norms. The role of these expectations as predictors of pro-social and anti-social behaviour has been analysed. The research is based on the assumption that every culture develops specific benchmarks in reference to which people judge various social phenomena. Creation of an individual conception of oneself and making a plan for one＇s life is based, to some extent, on social values which constitute the crucial element of every culture. The hypothesis to be verified in this study was the presence of a significant link between the occurrence of anti-social and pro-social behaviour and the adopted axiological assumptions concerning students and their behaviour. The subjects of the study were students and teachers from 18 schools representing three types of culture and three educational levels （primary, lower secondary, and upper secondary）. The total number of 1,212 students were observed （Goldsmith＇s Observational Questionnaire）, and 36 teachers were interviewed. The results indicate a link between the adopted school culture and teachers＇ functioning, and open perspectives of further research on the connection between the values in school curricula and the occurrence of behaviour violating social norms and bounds.
文摘When a normal shock wave interacts with a boundary layer along a wall surface in supersonic internal flows and the shock is strong enough to separate the boundary layer, the shock is bifurcated and a series of shocks called “shock train” is formed. The flow is decelerated from supersonic to subsonic through the whole interaction region that is referred to as “pseudo-shock”. In the present paper some characteristics of the shock train and pseudo-shock and some examples of the pseudo-shocks in some flow devices are described.
基金supported by the National Natural Science Foundation of China(No.10901107)the Innovation Program of Shanghai Municipal Education Commission(No.213ZZ136)
文摘In this paper,the reflection phenomenon of a vapor shock front(both sides of the front are in the vapor phase)in a van der Waals fluid is considered.Both the1-dimensional case and the multidimensional case are investigated.The authors find that under certain conditions,the reflected wave can be a single shock,or a single subsonic phase boundary,or one weak shock together with one subsonic phase boundary,which depends on the strength of the incident shock.This is different from the known result for the reflection of shock fronts in a gas dynamical system due to Chen in 1989.
