Because of my carelessness,Eq.（1）in the paper "An approximate method for calculating the fluid force and response of a circular cylinder at lock-in"(China Ocean Engineering,22（3）,2008,pp.373)should be f...Because of my carelessness,Eq.（1）in the paper "An approximate method for calculating the fluid force and response of a circular cylinder at lock-in"(China Ocean Engineering,22（3）,2008,pp.373)should be f’-1.0/U’-5.0=f’;-1.0/5.75f’;-5.0,not f’=U’/5.75. My apology is hereby given.展开更多
The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequentl...The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate.展开更多
In the present paper, we endeavor to accomplish a diagram, which demarcates the validity ranges for interfacial wave theories in a two-layer system, to meet the needs of design in ocean engineering. On the basis of th...In the present paper, we endeavor to accomplish a diagram, which demarcates the validity ranges for interfacial wave theories in a two-layer system, to meet the needs of design in ocean engineering. On the basis of the available solutions of periodic and solitary waves, we propose a guideline as principle to identify the validity regions of the interfacial wave theories in terms of wave period T, wave height H, upper layer thickness dl, and lower layer thick-ness d2, instead of only one parameter-water depth d as in the water surface wave circumstance. The diagram proposed here happens to be Le Mehaute＇s plot for free surface waves if water depth ratio r= d1/d2 approaches to infinity and the upper layer water density p1 to zero. On the contrary, the diagram for water surface waves can be used for two-layer interfacial waves if gravity acceleration g in it is replaced by the reduced gravity defined in this study under the condition of σ=（P2 - Pl）/P2 → 1.0 and r 〉 1.0. In the end, several figures of the validity ranges for various interfacial wavetheories in the two-layer fluid are given and compared with the results for surface waves.展开更多
The slack-taut state of tether is a particular adverse circumstance, which may influence the normal operation state of tension leg platform （TLP）. The dynamic responses of TLP with slack-taut tether are studied with...The slack-taut state of tether is a particular adverse circumstance, which may influence the normal operation state of tension leg platform （TLP）. The dynamic responses of TLP with slack-taut tether are studied with consideration of several nonlinear factors introduced by large amplitude motions. The time histories of stresses of tethers of a typical TLP in slack- taut state are given. In addition, the sensitivities of slack to stiffness and mass are investigated by varying the stiffness of tether and mass of TLP. It is found that slack is sensitive to the mass of TLP. The critical curved surfaces （ over which indicates the slack） for the increase of mass are obtained.展开更多
The Kármán vortex shedding is totally suppressed in flows past a wavy square-section cylinder at a Reynolds number of 100 and the wave steepness of 0.025. Such a phenomenon is illuminated by the numerical si...The Kármán vortex shedding is totally suppressed in flows past a wavy square-section cylinder at a Reynolds number of 100 and the wave steepness of 0.025. Such a phenomenon is illuminated by the numerical simulations. In the present study, the mechanism responsible for it is mainly attributed to the vertical vorticity. The geometric disturbance on the rear surface leads to the appearance of spanwise flow near the base. The specific vertical vorticity is generated on the rear surface and convecting into the near wake. The wake flow is recirculated with the appearance of the pair of recirculating cells. The interaction between the upper and lower shear layers is weakened by such cells, so that the vortex rolls could not be formed and the near wake flow becomes stable.展开更多
Piezoelectric actuators are mounted on both sides of a rectangular wing model. Possibility of the improvement of aircraft rolling power is investigated. All experiment proiects, including designing the wind tunnel mod...Piezoelectric actuators are mounted on both sides of a rectangular wing model. Possibility of the improvement of aircraft rolling power is investigated. All experiment proiects, including designing the wind tunnel model, checking the material constants, measuring the natural frequencies and checking the effects of actuators, guarantee the correctness and precision of the finite element model. The wind tunnel experiment results show that the calculations coincide with the experiments. The feasibility of fictitious control surface is validated.展开更多
The developmental dysplasia of the hip disease is in 1% of newborns, and it is a risk factor for dislocation of the hip;only 1 from 7000 newborns develops dislocation of the hip. Newborns were selected from public and...The developmental dysplasia of the hip disease is in 1% of newborns, and it is a risk factor for dislocation of the hip;only 1 from 7000 newborns develops dislocation of the hip. Newborns were selected from public and private hospitals in Celaya, Guanajuato. Parents were asked to sign informed consent. Clinical maneuvers were applied for diagnosis of developmental dysplasia of the hip, on three consecutive occasions, two by the same investigator and the third by a different observer: Ortolani, Barlow, Piston, Galeazzi, Peter Baden, the comparative sound transmission test, and comparative sound transmission with extension/flexion test were applied. The diagnosis was confirmed with ultrasound of hip, technique Graf, I healthy hip, II functionally immature, III subluxation, and IV dislocation. Sample size was 8 affected hips and 56 healthy hips. Kappa for intra observer and inter observer reliability were measured;the validity was measured by sensitivity, specificity, positive and negative predictive values, using the ultrasound diagnosis as the gold standard. The sample consisted of 78 neonates hips with female’s predominance. With comparative sound transmission test was obtained Kappa intra observer 0.80, Kappa inter observer 0.93, sensitivity 45.45%, specificity 96.27%, positive predictive value 66.67% and negative predictive value 91.49%;with comparative sound transmission with extension/flexion, was 0.83, 0.92, 72.73%, 95.52%, 72.73%, and 95.52%, respectively. The tests compared the sound transmission help better diagnose developmental dysplasia disease of the hip.展开更多
In this paper, equations calculating lift force of a rigid circular cylinder at lock-in in uniform flow are deduced in detail. Besides, equations calculating the lift force on a long flexible circular cylinder at lock...In this paper, equations calculating lift force of a rigid circular cylinder at lock-in in uniform flow are deduced in detail. Besides, equations calculating the lift force on a long flexible circular cylinder at lock-in are deduced based on mode analysis of a multi-degree freedom system. The simplified forms of these equations are also given. Furthemore, an approximate method to predict the forces and response of rigid circular cylinders and long flexible circular cylinders at lock-in is introduced in the case of low mass-damping ratio. A method to eliminate one deficiency of these equations is introduced. Comparison with experimental results shows the effectiveness of this approximate method.展开更多
The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation ...The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced.展开更多
It is demonstrated that when tension leg platform （TLP） moves with finite amplitude in waves, the inertia force, the drag force and the buoyancy acting on the platform are nonlinear functions of the response of TLP,...It is demonstrated that when tension leg platform （TLP） moves with finite amplitude in waves, the inertia force, the drag force and the buoyancy acting on the platform are nonlinear functions of the response of TLP, The tensions of the tethers are also nonlinear functions of the displacement of TLP. Then the displacement, the velocity and the acceleration of TLP should be taken into account when loads are calculated. In addition, equations of motions should be set up on the instantaneous position. A theo- retical model for analyzing the nonlinear behavior of a TLP with finite displacement is developed, in which multifold nonlinearities are taken into account, i.e., finite displace- ment, coupling of the six degrees of freedom, instantaneous position, instantaneous wet surface, free surface effects and viscous drag force, Based on the theoretical model, the comprehensive nonlinear differential equations are deduced. Then the nonlinear dynamic analysis of ISSC TLP in regular waves is performed in the time domain. The degenerative linear solution of the proposed nonlinear model is verified with existing published one. Furthermore, numerical results are presented, which illustrate that nonlinearities exert a significant influence on the dynamic responses of the TLP.展开更多
From the macroscopic point of view, expressions involving reservoir and operational parameters are established for investigating the stability of moving interface in piston- and non-piston-like displacements. In the c...From the macroscopic point of view, expressions involving reservoir and operational parameters are established for investigating the stability of moving interface in piston- and non-piston-like displacements. In the case of axisymmetrical piston-like displacement, the stability is related to the moving interface position and water to oil mobility ratio. The capillary effect on the stability of moving interface depends on whether or not the moving interface is already stable and correlates with the wettability of the reservoir rock. In the case of non-piston-like displacement, the stability of the front is governed by both the relative permeability and the mobility ratio.展开更多
There are many fault block fields in China. A fault block field consists of fault pools.The small fault pools can be viewed as the closed circle reservoirs in some case. In order to know the pressure change of the dev...There are many fault block fields in China. A fault block field consists of fault pools.The small fault pools can be viewed as the closed circle reservoirs in some case. In order to know the pressure change of the developed formation and provide the formation data for developing the fault block fields reasonably, the transient flow should be researched. In this paper, we use the automatic mesh generation technology and the finite element method to solve the transient flow problem for the well located in the closed circle reservoir, especially for the well located in an arbitrary position in the closed circle reservoir. The pressure diffusion process is visualized and the well-location factor concept is first proposed in this paper. The typical curves of pressure vs time for the well with different welllocation factors are presented. By comparing numerical results with the analytical solutions of the well located in the center of the closed circle reservoir, the numerical method is verified.展开更多
Objective: The aim of this study was to determine body composition, gynecological, and obstetric data, sex hormones, and prolactin serum levels in pre- (PREW) and postmenopausal women (PMW) with breast cancer (BC) and...Objective: The aim of this study was to determine body composition, gynecological, and obstetric data, sex hormones, and prolactin serum levels in pre- (PREW) and postmenopausal women (PMW) with breast cancer (BC) and compare them with a control group (CG) of healthy women. Methodology: BC patients without treatment or use of hormone replacement therapy, or hormonal birth control, and without data of metastasis were included. CG was matched for age, BMI, and menstrual cycle status. FSH, LH, E<sup>2</sup>, progesterone, testosterone, and prolactin (PRL) were measured using radioimmunoassay kits. Comparisons between BC and CG were made with “t” tests, and with the Mann-Whitney U-test;χ<sup>2</sup> test was used to compare the qualitative variables between the groups. Results: Seventy-two patients with BC, and 74 CG women were evaluated. Both groups presented overweight data, BMI (kg/mt<sup>2</sup>) = 27.21 ± 5.51 vs. 28.40 ± 4.66, p = ns, for BC patients and CG, respectively. In PREW, the age at menarche was later in BC patients compared to the CG (13.3 ± 1.36 years vs. 12.41 ± 1.27 years, p = 0.005). The PMW with BC presented a higher age at menarche and menopause compared to the women of the CG (13.51 ± 1.48 vs. 12.91 ± 1.41, p = 0.09, and 49.03 ± 2.86 vs. 45.5 ± 8.78, p = 0.03, respectively). PRL levels were significantly higher in PMW with BC, in comparison with the CG;median and minimum and maximum values (min-max) were: 14.7 ng/mL (3.6 - 52.7) vs. 5.9 ng/mL (1.9 - 33.3), p = 0.005). A higher percentage of PMW with BC (26.0% vs. 7.1%, χ<sup>2</sup> = 5.57, p = 0.01) presented hyperprolactinemia (PRL serum levels > 20 ng/mL), compared to the GC. Conclusions: The higher levels of PRL in PMW with BC compared with CG, suggest a proliferative effect of this hormone in the affected breast tissue. This study demonstrates the need to use biological markers such as PRL to determine the risk of BC in PMW.展开更多
A numerical approach to optimize dimensionless parameters of water-flooding porous media flows is proposed based on the analysis of the sensitivity factor defined as the variation ration of a target function with resp...A numerical approach to optimize dimensionless parameters of water-flooding porous media flows is proposed based on the analysis of the sensitivity factor defined as the variation ration of a target function with respect to the variation of dimensionless parameters. A complete set of scaling criteria for water-flooding reservoir of five-spot well pattern case is derived from the 3-D governing equations, involving the gravitational force, the capillary force and the compressibility of water, oil and rock. By using this approach, we have estimated the influences of each dimensionless parameter on experimental results, and thus sorting out the dominant ones with larger sensitivity factors ranging from 10?4 to 100.展开更多
More and more piezoelectric materials and structures have been used for structure control in aviation and aerospace industry. More efficient and convenient computation method for large complex structure with piezoelec...More and more piezoelectric materials and structures have been used for structure control in aviation and aerospace industry. More efficient and convenient computation method for large complex structure with piezoelectric actuation devices is required. A load simulation method of piezoelectric actuation is presented in this paper. By this method, the freedom degree of finite element simulation is significantly reduced, the difficulty in defining in-plane voltage for multi-layers piezoelectric composite is overcome and the transfer computation between material main direction and the element main direction is simplified. The concept of simulation load is comprehensible and suitable for engineers of structure strength in shape and vibration control, thereby is valuable for promoting the application of piezoelectric material and structures in practical aviation and aerospace fields.展开更多
With the finite volume method, a 2D numerical model for seepage in unsaturated soil has been established to study the rainfall infiltration in the fractured slope. The result shows that more rain may infiltrate into t...With the finite volume method, a 2D numerical model for seepage in unsaturated soil has been established to study the rainfall infiltration in the fractured slope. The result shows that more rain may infiltrate into the slope due to existing fracture and then the pore pressure rises correspondingly. Very probably, it is one of the crucial factors accounting for slope failure. Furthermore a preliminary study has been conducted to investigate the influence of various fracture and rainfall factors such as the depth, width and location of a crack, surface condition, rainfall intensity and duration. Pore pressure and water volumetric content during the transient seepage are carefully examined to reveal the intrinsic mechanism.展开更多
With the PDPA(Phase Doppler Particle Analyzer) measurement technology,the probability distributions of particle impact and lift-off velocities on bed surface and the particle velocity distributions at different height...With the PDPA(Phase Doppler Particle Analyzer) measurement technology,the probability distributions of particle impact and lift-off velocities on bed surface and the particle velocity distributions at different heights are detected in a wind tunnel. The results show that the probability distribution of impact and lift-off velocities of sand grains can be expressed by a log-normal function,and that of impact and lift-off angles complies with an exponential function. The mean impact angle is between 28° and 39°,and the mean lift-off angle ranges from 30° to 44°. The mean lift-off velocity is 0.81-0.9 times the mean impact velocity. The proportion of backward-impacting particles is 0.05-0.11,and that of backward-entrained particles ranges from 0.04 to 0.13. The probability distribution of particle horizontal velocity at 4 mm height is positive skew,the horizontal velocity of particles at 20 mm height varies widely,and the variation of the particle horizontal velocity at 80 mm height is less than that at 20 mm height. The probability distribution of particle vertical velocity at different heights can be described as a normal function.展开更多
Based on the theory of the pumping well test,the transient injection well test was suggested in this paper.The design method and the scope of application are discussed in detail.The mathematical models are developed f...Based on the theory of the pumping well test,the transient injection well test was suggested in this paper.The design method and the scope of application are discussed in detail.The mathematical models are developed for the short-time and long-time transient injection test respectively.A double logarithm type curve matching method was introduced for analyzing the field transient injection test data.A set of methods for the transient injection test design,experiment performance and data analysis were established.Some field tests were analyzed,and the results show that the test model and method are suitable for the transient injection test and can be used to deal with the real engineering problems.展开更多
The water content distribution in the surface layer of Maoping slope has been studied by testing the water content at 31 control sites.The water content profiles at these sites have also been determined.The water cont...The water content distribution in the surface layer of Maoping slope has been studied by testing the water content at 31 control sites.The water content profiles at these sites have also been determined.The water content distributions at different segments have been obtained by using the Kriging method of geostatistics.By comparing the water content distributions with the landform of the slope,it was shown that the water content is closely dependent on the landform of the slope.The water content distribution in the surface layer provided a fundamental basis for landslide predication and treatment.展开更多
Hydrocyclones are widely used in industry, of which the geometrical design using CFD techniques is gaining more popularity in recent years. In this study, the Euler-Euler approach and the Reynolds stress model are app...Hydrocyclones are widely used in industry, of which the geometrical design using CFD techniques is gaining more popularity in recent years. In this study, the Euler-Euler approach and the Reynolds stress model are applied to simulate the liquid-solid flowfield in a hydrocyclone. The methodology is validated by a good agreement between experimental data and numerical results. Within the research range, the simulation indicates that the liquid-solid separation mainly occurs in the conical segment, and increasing conical height or decreasing cylindrical height helps to improve the grade efficiencies of solid particles. Based on these results, two of the same hydrocyclones are designed and installed in series to establish a liquid-solid separation system. Many experiments are then conducted under different conditions, in which the effects of the water cut and the second hydrocyclone on the separation are investigated. The results also confirm that smaller solid particles are more susceptible to the inlet conditions, and the second hydrocyclone plays a more important role as the water cut reduces.展开更多
文摘Because of my carelessness,Eq.（1）in the paper "An approximate method for calculating the fluid force and response of a circular cylinder at lock-in"(China Ocean Engineering,22（3）,2008,pp.373)should be f’-1.0/U’-5.0=f’;-1.0/5.75f’;-5.0,not f’=U’/5.75. My apology is hereby given.
基金The project supported by the Innovative Project of CAS (KJCX-SW-L08)the National Basic Research Program of China(973)
文摘The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate.
基金the Knowledge Innovation Project of CAS(KJCX-YW-L02)the National 863 Project of China(2006AAO9A103-4)+1 种基金China National Oil Corporation in Beijing(CNOOC)the National Natural Science Foundation of China(10672056).
文摘In the present paper, we endeavor to accomplish a diagram, which demarcates the validity ranges for interfacial wave theories in a two-layer system, to meet the needs of design in ocean engineering. On the basis of the available solutions of periodic and solitary waves, we propose a guideline as principle to identify the validity regions of the interfacial wave theories in terms of wave period T, wave height H, upper layer thickness dl, and lower layer thick-ness d2, instead of only one parameter-water depth d as in the water surface wave circumstance. The diagram proposed here happens to be Le Mehaute＇s plot for free surface waves if water depth ratio r= d1/d2 approaches to infinity and the upper layer water density p1 to zero. On the contrary, the diagram for water surface waves can be used for two-layer interfacial waves if gravity acceleration g in it is replaced by the reduced gravity defined in this study under the condition of σ=（P2 - Pl）/P2 → 1.0 and r 〉 1.0. In the end, several figures of the validity ranges for various interfacial wavetheories in the two-layer fluid are given and compared with the results for surface waves.
基金supported by the National High-Tech Research and Development Program of China(863 Program,Grant No.2006AA09Z350)the National Natural Science Foundation of China(Grant No.10702073)the"Knowledge Innovation Program"of Chinese Academy of Sciences(Grant No.KJCX2-YW-L02)
文摘The slack-taut state of tether is a particular adverse circumstance, which may influence the normal operation state of tension leg platform （TLP）. The dynamic responses of TLP with slack-taut tether are studied with consideration of several nonlinear factors introduced by large amplitude motions. The time histories of stresses of tethers of a typical TLP in slack- taut state are given. In addition, the sensitivities of slack to stiffness and mass are investigated by varying the stiffness of tether and mass of TLP. It is found that slack is sensitive to the mass of TLP. The critical curved surfaces （ over which indicates the slack） for the increase of mass are obtained.
文摘The Kármán vortex shedding is totally suppressed in flows past a wavy square-section cylinder at a Reynolds number of 100 and the wave steepness of 0.025. Such a phenomenon is illuminated by the numerical simulations. In the present study, the mechanism responsible for it is mainly attributed to the vertical vorticity. The geometric disturbance on the rear surface leads to the appearance of spanwise flow near the base. The specific vertical vorticity is generated on the rear surface and convecting into the near wake. The wake flow is recirculated with the appearance of the pair of recirculating cells. The interaction between the upper and lower shear layers is weakened by such cells, so that the vortex rolls could not be formed and the near wake flow becomes stable.
文摘Piezoelectric actuators are mounted on both sides of a rectangular wing model. Possibility of the improvement of aircraft rolling power is investigated. All experiment proiects, including designing the wind tunnel model, checking the material constants, measuring the natural frequencies and checking the effects of actuators, guarantee the correctness and precision of the finite element model. The wind tunnel experiment results show that the calculations coincide with the experiments. The feasibility of fictitious control surface is validated.
文摘The developmental dysplasia of the hip disease is in 1% of newborns, and it is a risk factor for dislocation of the hip;only 1 from 7000 newborns develops dislocation of the hip. Newborns were selected from public and private hospitals in Celaya, Guanajuato. Parents were asked to sign informed consent. Clinical maneuvers were applied for diagnosis of developmental dysplasia of the hip, on three consecutive occasions, two by the same investigator and the third by a different observer: Ortolani, Barlow, Piston, Galeazzi, Peter Baden, the comparative sound transmission test, and comparative sound transmission with extension/flexion test were applied. The diagnosis was confirmed with ultrasound of hip, technique Graf, I healthy hip, II functionally immature, III subluxation, and IV dislocation. Sample size was 8 affected hips and 56 healthy hips. Kappa for intra observer and inter observer reliability were measured;the validity was measured by sensitivity, specificity, positive and negative predictive values, using the ultrasound diagnosis as the gold standard. The sample consisted of 78 neonates hips with female’s predominance. With comparative sound transmission test was obtained Kappa intra observer 0.80, Kappa inter observer 0.93, sensitivity 45.45%, specificity 96.27%, positive predictive value 66.67% and negative predictive value 91.49%;with comparative sound transmission with extension/flexion, was 0.83, 0.92, 72.73%, 95.52%, 72.73%, and 95.52%, respectively. The tests compared the sound transmission help better diagnose developmental dysplasia disease of the hip.
基金the National High Technology Researchand Development Programof China (863Program,Grant Nos.2006AA09Z301 and 2006AA09A103-4)the National Natural Science Foundation of China(Grant No10532070)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant NoKJCX2-YW-L02)
文摘In this paper, equations calculating lift force of a rigid circular cylinder at lock-in in uniform flow are deduced in detail. Besides, equations calculating the lift force on a long flexible circular cylinder at lock-in are deduced based on mode analysis of a multi-degree freedom system. The simplified forms of these equations are also given. Furthemore, an approximate method to predict the forces and response of rigid circular cylinders and long flexible circular cylinders at lock-in is introduced in the case of low mass-damping ratio. A method to eliminate one deficiency of these equations is introduced. Comparison with experimental results shows the effectiveness of this approximate method.
基金Project supported by the National Natural Science Foundation of China (No.60034010) the Australia Research Council Discovery-Projects Grant (No.DP0210716)
文摘The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced.
基金Project supported by "Creativeness Project of the Tenth Five-Year Plan" of Chinese Academy of Sciences (No.KJCX2-SW-L03)the National High-Tech Research and Development Program of China (863 Program) (No.2004AA617010)
文摘It is demonstrated that when tension leg platform （TLP） moves with finite amplitude in waves, the inertia force, the drag force and the buoyancy acting on the platform are nonlinear functions of the response of TLP, The tensions of the tethers are also nonlinear functions of the displacement of TLP. Then the displacement, the velocity and the acceleration of TLP should be taken into account when loads are calculated. In addition, equations of motions should be set up on the instantaneous position. A theo- retical model for analyzing the nonlinear behavior of a TLP with finite displacement is developed, in which multifold nonlinearities are taken into account, i.e., finite displace- ment, coupling of the six degrees of freedom, instantaneous position, instantaneous wet surface, free surface effects and viscous drag force, Based on the theoretical model, the comprehensive nonlinear differential equations are deduced. Then the nonlinear dynamic analysis of ISSC TLP in regular waves is performed in the time domain. The degenerative linear solution of the proposed nonlinear model is verified with existing published one. Furthermore, numerical results are presented, which illustrate that nonlinearities exert a significant influence on the dynamic responses of the TLP.
基金the National Basic Research Program of China (2005CB221300)the Innovative Project of Chinese Academy of Sciences (KJCX-SW-L08)
文摘From the macroscopic point of view, expressions involving reservoir and operational parameters are established for investigating the stability of moving interface in piston- and non-piston-like displacements. In the case of axisymmetrical piston-like displacement, the stability is related to the moving interface position and water to oil mobility ratio. The capillary effect on the stability of moving interface depends on whether or not the moving interface is already stable and correlates with the wettability of the reservoir rock. In the case of non-piston-like displacement, the stability of the front is governed by both the relative permeability and the mobility ratio.
文摘There are many fault block fields in China. A fault block field consists of fault pools.The small fault pools can be viewed as the closed circle reservoirs in some case. In order to know the pressure change of the developed formation and provide the formation data for developing the fault block fields reasonably, the transient flow should be researched. In this paper, we use the automatic mesh generation technology and the finite element method to solve the transient flow problem for the well located in the closed circle reservoir, especially for the well located in an arbitrary position in the closed circle reservoir. The pressure diffusion process is visualized and the well-location factor concept is first proposed in this paper. The typical curves of pressure vs time for the well with different welllocation factors are presented. By comparing numerical results with the analytical solutions of the well located in the center of the closed circle reservoir, the numerical method is verified.
文摘Objective: The aim of this study was to determine body composition, gynecological, and obstetric data, sex hormones, and prolactin serum levels in pre- (PREW) and postmenopausal women (PMW) with breast cancer (BC) and compare them with a control group (CG) of healthy women. Methodology: BC patients without treatment or use of hormone replacement therapy, or hormonal birth control, and without data of metastasis were included. CG was matched for age, BMI, and menstrual cycle status. FSH, LH, E<sup>2</sup>, progesterone, testosterone, and prolactin (PRL) were measured using radioimmunoassay kits. Comparisons between BC and CG were made with “t” tests, and with the Mann-Whitney U-test;χ<sup>2</sup> test was used to compare the qualitative variables between the groups. Results: Seventy-two patients with BC, and 74 CG women were evaluated. Both groups presented overweight data, BMI (kg/mt<sup>2</sup>) = 27.21 ± 5.51 vs. 28.40 ± 4.66, p = ns, for BC patients and CG, respectively. In PREW, the age at menarche was later in BC patients compared to the CG (13.3 ± 1.36 years vs. 12.41 ± 1.27 years, p = 0.005). The PMW with BC presented a higher age at menarche and menopause compared to the women of the CG (13.51 ± 1.48 vs. 12.91 ± 1.41, p = 0.09, and 49.03 ± 2.86 vs. 45.5 ± 8.78, p = 0.03, respectively). PRL levels were significantly higher in PMW with BC, in comparison with the CG;median and minimum and maximum values (min-max) were: 14.7 ng/mL (3.6 - 52.7) vs. 5.9 ng/mL (1.9 - 33.3), p = 0.005). A higher percentage of PMW with BC (26.0% vs. 7.1%, χ<sup>2</sup> = 5.57, p = 0.01) presented hyperprolactinemia (PRL serum levels > 20 ng/mL), compared to the GC. Conclusions: The higher levels of PRL in PMW with BC compared with CG, suggest a proliferative effect of this hormone in the affected breast tissue. This study demonstrates the need to use biological markers such as PRL to determine the risk of BC in PMW.
基金This work was supported by the National 973 Project(Grant No.G1999022511)the Innovation Project of Chinese Academy of Sciences.
文摘A numerical approach to optimize dimensionless parameters of water-flooding porous media flows is proposed based on the analysis of the sensitivity factor defined as the variation ration of a target function with respect to the variation of dimensionless parameters. A complete set of scaling criteria for water-flooding reservoir of five-spot well pattern case is derived from the 3-D governing equations, involving the gravitational force, the capillary force and the compressibility of water, oil and rock. By using this approach, we have estimated the influences of each dimensionless parameter on experimental results, and thus sorting out the dominant ones with larger sensitivity factors ranging from 10?4 to 100.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10772183 and 10532070) Foundation Program of Chinese Academy of Sciences (Grant No. KJCX2-YW-L07)
文摘More and more piezoelectric materials and structures have been used for structure control in aviation and aerospace industry. More efficient and convenient computation method for large complex structure with piezoelectric actuation devices is required. A load simulation method of piezoelectric actuation is presented in this paper. By this method, the freedom degree of finite element simulation is significantly reduced, the difficulty in defining in-plane voltage for multi-layers piezoelectric composite is overcome and the transfer computation between material main direction and the element main direction is simplified. The concept of simulation load is comprehensible and suitable for engineers of structure strength in shape and vibration control, thereby is valuable for promoting the application of piezoelectric material and structures in practical aviation and aerospace fields.
基金This research was supported by the "973" Project of Ministry of Science and Technology of China (Grant No. 2002CB412703) the National Natural Science Foundation of China (Grant No. 10332050)the Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KJCX2-SW-L1-4).
文摘With the finite volume method, a 2D numerical model for seepage in unsaturated soil has been established to study the rainfall infiltration in the fractured slope. The result shows that more rain may infiltrate into the slope due to existing fracture and then the pore pressure rises correspondingly. Very probably, it is one of the crucial factors accounting for slope failure. Furthermore a preliminary study has been conducted to investigate the influence of various fracture and rainfall factors such as the depth, width and location of a crack, surface condition, rainfall intensity and duration. Pore pressure and water volumetric content during the transient seepage are carefully examined to reveal the intrinsic mechanism.
基金the National Natural Science Foundation of China (Grant No. 10532030)the National Basic Research Program of China (Grant No. G2000048702)
文摘With the PDPA(Phase Doppler Particle Analyzer) measurement technology,the probability distributions of particle impact and lift-off velocities on bed surface and the particle velocity distributions at different heights are detected in a wind tunnel. The results show that the probability distribution of impact and lift-off velocities of sand grains can be expressed by a log-normal function,and that of impact and lift-off angles complies with an exponential function. The mean impact angle is between 28° and 39°,and the mean lift-off angle ranges from 30° to 44°. The mean lift-off velocity is 0.81-0.9 times the mean impact velocity. The proportion of backward-impacting particles is 0.05-0.11,and that of backward-entrained particles ranges from 0.04 to 0.13. The probability distribution of particle horizontal velocity at 4 mm height is positive skew,the horizontal velocity of particles at 20 mm height varies widely,and the variation of the particle horizontal velocity at 80 mm height is less than that at 20 mm height. The probability distribution of particle vertical velocity at different heights can be described as a normal function.
基金This paper has been financially supported by the Special Funds for Major State Basic Re-scarch Projcct(Grant No,2002CB412703)Knowledge Innovation Project of Chinese Academy of Sciences(Grant No.KJCX2-SW-LI-4).
文摘Based on the theory of the pumping well test,the transient injection well test was suggested in this paper.The design method and the scope of application are discussed in detail.The mathematical models are developed for the short-time and long-time transient injection test respectively.A double logarithm type curve matching method was introduced for analyzing the field transient injection test data.A set of methods for the transient injection test design,experiment performance and data analysis were established.Some field tests were analyzed,and the results show that the test model and method are suitable for the transient injection test and can be used to deal with the real engineering problems.
基金This work was supported by the Special Funds for Major State Basic Research Project(Grant No.2002CB412703)the National Natural Science Foundations of China(Grant No.10372104)the Knowledge Innovation Project of Chinese Academy of Sciences(Grant No.KJCX2-SW-L1-4).
文摘The water content distribution in the surface layer of Maoping slope has been studied by testing the water content at 31 control sites.The water content profiles at these sites have also been determined.The water content distributions at different segments have been obtained by using the Kriging method of geostatistics.By comparing the water content distributions with the landform of the slope,it was shown that the water content is closely dependent on the landform of the slope.The water content distribution in the surface layer provided a fundamental basis for landslide predication and treatment.
文摘Hydrocyclones are widely used in industry, of which the geometrical design using CFD techniques is gaining more popularity in recent years. In this study, the Euler-Euler approach and the Reynolds stress model are applied to simulate the liquid-solid flowfield in a hydrocyclone. The methodology is validated by a good agreement between experimental data and numerical results. Within the research range, the simulation indicates that the liquid-solid separation mainly occurs in the conical segment, and increasing conical height or decreasing cylindrical height helps to improve the grade efficiencies of solid particles. Based on these results, two of the same hydrocyclones are designed and installed in series to establish a liquid-solid separation system. Many experiments are then conducted under different conditions, in which the effects of the water cut and the second hydrocyclone on the separation are investigated. The results also confirm that smaller solid particles are more susceptible to the inlet conditions, and the second hydrocyclone plays a more important role as the water cut reduces.
