Objective To summarize the experience and evaluate the efficacy of treatment of urethral stricture using direct visual internal urethrotomy ( DVIU) . Methods The clinical data of 361 patients ( age range 16 - 72 years...Objective To summarize the experience and evaluate the efficacy of treatment of urethral stricture using direct visual internal urethrotomy ( DVIU) . Methods The clinical data of 361 patients ( age range 16 - 72 years, mean age 38 years) with urethral stricture who underwent urethrotomy from 1990 to 2010 was retrospectively ana-展开更多
As a result of advances in horizontal comple- tions and multi-stage hydraulic fracturing, the U.S. has been able to economically develop several decades of worth of natural gas. However, a considerable concern has ris...As a result of advances in horizontal comple- tions and multi-stage hydraulic fracturing, the U.S. has been able to economically develop several decades of worth of natural gas. However, a considerable concern has risen on the economic viability of shale gas development for reasons associated with the fast production declines as well as recent down-turns of natural gas prices besides rises in the costs of new technologies. Therefore, an economic analysis is required to investigate the profitability of the re- fracturing treatment of unconventional gas resources. Net present value of cash flows and internal rate of return are calculated for a range of gas prices considering 20 years of natural gas production from a typical unconventional shale gas reservoir. A systematic comparison is then accom- plished for three scenarios： （1） re-fracturing versus no re- fracturing, （2） combination of re-fracturing and drilling new wells, and （3） time-dependent re-fracturing treatment. Further, this paper incorporates the cost of re-fracturing treatment, the cost of drilling a new horizontal well, the water treatment cost, as well as the current and future price of natural gas in the model. The findings of this work would help the future re-stimulation development plans of the emerging unconventional shale gas plays.展开更多
In this paper, a constitutive model is proposed for piezoelectric material solids containing distributed cracks. The model is formulated in a framework of continuum damage mechanics using second rank tensors as intern...In this paper, a constitutive model is proposed for piezoelectric material solids containing distributed cracks. The model is formulated in a framework of continuum damage mechanics using second rank tensors as internal variables. The Helrnhotlz free energy of piezoelectric mate- rials with damage is then expressed as a polynomial including the transformed strains, the electric field vector and the tensorial damage variables by using the integrity bases restricted by the initial orthotropic symmetry of the material. By using the Talreja＇s tensor valued internal state damage variables as well as the Helrnhotlz free energy of the piezoelectric material, the constitutive relations of piezoelectric materials with damage are derived. The model is applied to a special case of piezoelectric plate with transverse matrix cracks. With the Kirchhoff hypothesis of plate, the free vibration equations of the piezoelectric rectangular plate considering damage is established. By using Galerkin method, the equations are solved. Numerical results show the effect of the damage on the free vibration of the piezoelectric plate under the close-circuit condition, and the present results are compared with those of the three-dimensional theory.展开更多
L’Assommoir is the seventh installment of Les Rougon-Macquart book series,writted byÉmile Zola,a famous French naturalism novelist and theorist.Twenty years of Gervaise’s life from coming to Paris in 1850 to tr...L’Assommoir is the seventh installment of Les Rougon-Macquart book series,writted byÉmile Zola,a famous French naturalism novelist and theorist.Twenty years of Gervaise’s life from coming to Paris in 1850 to tragic deaths in 1869,is described in L’Assommoir.This thesis will make a detailed discussion and analysis of all the factors contributing to Gervaise’s miserable fate,by analyzing the story of L’Assommoir through the Freud’s internalization values approach.It is meant to how to locate the so⁃cial role of gender and maintain women’s interests may be were revelations,through the miserable fate of Gervaise.展开更多
文摘Objective To summarize the experience and evaluate the efficacy of treatment of urethral stricture using direct visual internal urethrotomy ( DVIU) . Methods The clinical data of 361 patients ( age range 16 - 72 years, mean age 38 years) with urethral stricture who underwent urethrotomy from 1990 to 2010 was retrospectively ana-
文摘As a result of advances in horizontal comple- tions and multi-stage hydraulic fracturing, the U.S. has been able to economically develop several decades of worth of natural gas. However, a considerable concern has risen on the economic viability of shale gas development for reasons associated with the fast production declines as well as recent down-turns of natural gas prices besides rises in the costs of new technologies. Therefore, an economic analysis is required to investigate the profitability of the re- fracturing treatment of unconventional gas resources. Net present value of cash flows and internal rate of return are calculated for a range of gas prices considering 20 years of natural gas production from a typical unconventional shale gas reservoir. A systematic comparison is then accom- plished for three scenarios： （1） re-fracturing versus no re- fracturing, （2） combination of re-fracturing and drilling new wells, and （3） time-dependent re-fracturing treatment. Further, this paper incorporates the cost of re-fracturing treatment, the cost of drilling a new horizontal well, the water treatment cost, as well as the current and future price of natural gas in the model. The findings of this work would help the future re-stimulation development plans of the emerging unconventional shale gas plays.
基金the National Natural Science Foundation of China (10572049)
文摘In this paper, a constitutive model is proposed for piezoelectric material solids containing distributed cracks. The model is formulated in a framework of continuum damage mechanics using second rank tensors as internal variables. The Helrnhotlz free energy of piezoelectric mate- rials with damage is then expressed as a polynomial including the transformed strains, the electric field vector and the tensorial damage variables by using the integrity bases restricted by the initial orthotropic symmetry of the material. By using the Talreja＇s tensor valued internal state damage variables as well as the Helrnhotlz free energy of the piezoelectric material, the constitutive relations of piezoelectric materials with damage are derived. The model is applied to a special case of piezoelectric plate with transverse matrix cracks. With the Kirchhoff hypothesis of plate, the free vibration equations of the piezoelectric rectangular plate considering damage is established. By using Galerkin method, the equations are solved. Numerical results show the effect of the damage on the free vibration of the piezoelectric plate under the close-circuit condition, and the present results are compared with those of the three-dimensional theory.
文摘L’Assommoir is the seventh installment of Les Rougon-Macquart book series,writted byÉmile Zola,a famous French naturalism novelist and theorist.Twenty years of Gervaise’s life from coming to Paris in 1850 to tragic deaths in 1869,is described in L’Assommoir.This thesis will make a detailed discussion and analysis of all the factors contributing to Gervaise’s miserable fate,by analyzing the story of L’Assommoir through the Freud’s internalization values approach.It is meant to how to locate the so⁃cial role of gender and maintain women’s interests may be were revelations,through the miserable fate of Gervaise.
