Based on the databases of soils, meteorology, crop production, and agricultural management, changes in the soil organic carbon (SOC) of agro ecosystems in Jiangsu Province were simulated by using a soil organic carbo...Based on the databases of soils, meteorology, crop production, and agricultural management, changes in the soil organic carbon (SOC) of agro ecosystems in Jiangsu Province were simulated by using a soil organic carbon model with a linkage of GIS. Four data sets of soil organic carbon measured from various field experiments in Jiangsu Province were used to validate the model. It was demonstrated that the model simulation in general agreed with the field measurements. Model simulation indicated that the SOC content in approximately 77% of the agricultural soils in Jiangsu Province has increased since the Second National Soil Survey completed in the early 1980s. Compared with the values in 1985, the SOC content in 2000 was estimated to increase by 1.03.0 g kg 1 for the north and the coastal areas of the province, and by 3.55.0 g kg 1 for the region of Tai Lake in the south. A slight decrease (about 0.51.5 g kg 1 ) was estimated for the central region of Jiangsu Province and the Nanjing Zhenjiang hilly area. Model prediction for 2010 A.D. under two scena rios, i.e., with 30 and 50% of the harvested crop straw incorporation, suggested that the SOC in Jiangsu Province would increase, and thus that the agricultural soils would have potential as organic carbon storage. The incorporation of crop straw into soils is of great benefit to increase soil carbon storage, consequently to benefit the control of the rise of atmospheric CO 2 concentration and to maintain the sustainable development of agriculture.展开更多
Finance and Marketing Department of ING Group, which is one of the largest financial group in Europe, published its Forecast Report on Chinese auto industry. The Report said that in the coming a few years, the develop...Finance and Marketing Department of ING Group, which is one of the largest financial group in Europe, published its Forecast Report on Chinese auto industry. The Report said that in the coming a few years, the development of China's auto industry will surpass that of Canada,展开更多
When condensation occurs in supersonic flow fields, the flow is thected by the latent heat released. In the present study, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitediffere...When condensation occurs in supersonic flow fields, the flow is thected by the latent heat released. In the present study, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitedifference scheme with a second-order fractionabetep for time integration. Baldwin-Lomax model, that is the algebraic model, called the zero equation model was used in the computations. The effects of initial conditions (initial degree of supersaturation and total temperature in the reservoir) on condensing fiow of moist air in a supersonic circular half nozzle were investigated. In this case, the effect of condensation on the boundary layer was also discussed in detail. As a result, the simulated flow fields were compared with experimental data in good agreement, and the velocity and temperature profiles were largely changed by condensation.展开更多
Techniques using Coanda effect have been applied to the fiuid control devices. In this field, experimental studies were so far performed for the spiral jet obtained by the Coanda jet issuing from a conical cylinder wi...Techniques using Coanda effect have been applied to the fiuid control devices. In this field, experimental studies were so far performed for the spiral jet obtained by the Coanda jet issuing from a conical cylinder with an annular slit, thrust vectoring of supersonic Coanda jets and so on. It is important from the viewpoints of effective applications to investigate the characteristics of the supersonic Coanda jet in detail. In the present study the effects of pressure ratios and nozzle configurations on the characteristics of the supersonic Coanda jet have been investigated experhoentally by a schlieren optical method and pressure measurements. Furthermore, Navier-Stokes equations were solved numerically using a 2nd-order TVD finite-volume scheme with a 3rd-rorder three stage Runge-Kutta method for time integration. k - ε model was used in the computations. The effects of initial conditions on Coandaflow were investigated numerically As a result, the simulated flow helds were compared with experimental data in good agreement qualitatively.展开更多
When non-equilibrium condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, in order to control the transonic flow field with shock wave, a condensing f...When non-equilibrium condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, in order to control the transonic flow field with shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock / boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically and experimentally. The result obtained showed that the total pressure loss in the flow fields might be effectively reduced by the suitable combination between non-equilibrium condensation and the position of porous wall.展开更多
When condensation occurs in supersonic flow fields, the flow is affected by the latent heat released, and if the heat released exceeds a certain quantity, a condensation shock wave will occur There are many papers for...When condensation occurs in supersonic flow fields, the flow is affected by the latent heat released, and if the heat released exceeds a certain quantity, a condensation shock wave will occur There are many papers for the passive control of shock-boundary layer interaction using the porous wall with a plenum underneath on the application of the technique to transonic airfoil flows. In the present study, this passive technique is applied to the control of a steady condensation shock wave generated in a supersonic nozzle. In order to clarify the effect of the passive shockboundary layer control on condensation shock, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration. As a result, the simulated flow fields were compared with experimental data in good agreement and the aspect of the flow field has been clarified.展开更多
When condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, a condensing flow was produced by an expansion of moist air in a supersonic circular nozzle,...When condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, a condensing flow was produced by an expansion of moist air in a supersonic circular nozzle, and, by inserting a wedge-type shock generator placed in the supersonic part of the nozzle, the experimental investigations were carried out to clarify the effect of condensation on the normal shock wave and the boundary layer. As a result, the position of the shock wave relative to the condensation zone was discussed, together with the effect of condensation on pressure fiuctuations. Furthermore, a compressible viscous two-phase flow of moist air in a supersonic half nozzle was calculated to investigate the effect of condensation on boundary layer.展开更多
In order to improve the performance of a Wells turbine, the effect of guide vanes with various gaps between turbine rotor and guide vane has been clarified by model testing and numerical simulation.The results have be...In order to improve the performance of a Wells turbine, the effect of guide vanes with various gaps between turbine rotor and guide vane has been clarified by model testing and numerical simulation.The results have been compared with those of the case without guide vanes. It is found that the overall characteristics are considerably improved by the inlet guide vanes. Furthermore,a suitable choice of design factor for the gap has been suggested.展开更多
The influences of second order Polarization Mode Dispersion (PMD) on light pulse are discussed from changing of the pulse shape and eye graph when considering second order PMD. The results by numerical simulation show...The influences of second order Polarization Mode Dispersion (PMD) on light pulse are discussed from changing of the pulse shape and eye graph when considering second order PMD. The results by numerical simulation show that the second-order PMD components associated with depolarization of the principal states can cause significant system impairments that cause overshoot at the edge of pulse. By the same time the compensation method for second-order PMD are also discussed by theoretically and experimentally. The experiment results show that it is very effective to compensate second order PMD by using two stage PMD compensator.展开更多
The total efficiency of power plants depends on the energy conversion in a combustor and a turbine .Considerably higher energy transfer rates can be obtained from a pulsed combustion.but unsteady flow of a single jet ...The total efficiency of power plants depends on the energy conversion in a combustor and a turbine .Considerably higher energy transfer rates can be obtained from a pulsed combustion.but unsteady flow of a single jet combustor reduces the turbine efficiency.Therefore.two pulse combustors were set in parallel and connected to a settling chamber that supplies a flow with constant pressure to the turbine.The aim of investigations presented here is a demonstration of technical feasibility for industrial applications and to show the benefits obtained from the pulse combustors.展开更多
This paper presents the sampling and feedback control techniques, which are the kernel of our experiment on adaptive Polarization Mode Dispersion (PMD) compensation for optical fiber communication systems. Some key po...This paper presents the sampling and feedback control techniques, which are the kernel of our experiment on adaptive Polarization Mode Dispersion (PMD) compensation for optical fiber communication systems. Some key points on sampling and feedback techniques are discussed and practical resolutions for them are put forward.展开更多
A rapid expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomena. Thereby, if the heat released by condensation of water vapour exceeds a certain quantity, the flow wi...A rapid expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomena. Thereby, if the heat released by condensation of water vapour exceeds a certain quantity, the flow will become unstable and periodic flow oscillations of the unsteady condensation shock wave will occur. For the passive control of shock-boundary layer interaction using the porous wall with a plenum underneath, many papers have been presented on the application of the technique to transonic airfoil flows. In this paper, the passive technique is applied to three types of oscillations of the unsteady condensation shock wave generated in a supersonic nozzle in order to suppress the unsteady behavior As a result, the effects of number of slits and length of cavity on the aspect of flow field have been clarified numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration.展开更多
A compression wave discharged from an open end of a tube causes positive impulsive noise. Active noise cancellation which is the canceling of the noise by the addition of an inverse wave is a useful technique for redu...A compression wave discharged from an open end of a tube causes positive impulsive noise. Active noise cancellation which is the canceling of the noise by the addition of an inverse wave is a useful technique for reducing impulsive noise. The main objective of this study is to present the design for a negative impulsive wave generator utilizing unsteady mass influx. In this paper, in order to clarify the relationship between the unsteady mass influx and the negative impulsive wave! numerical and aeroacoustic analyses have been carried out using an unsteady expansion wave discharged from an open end of a shock tube. As a result, the effect of an unsteady expansion wave on a negative impulsive wave was clarified.展开更多
文摘Based on the databases of soils, meteorology, crop production, and agricultural management, changes in the soil organic carbon (SOC) of agro ecosystems in Jiangsu Province were simulated by using a soil organic carbon model with a linkage of GIS. Four data sets of soil organic carbon measured from various field experiments in Jiangsu Province were used to validate the model. It was demonstrated that the model simulation in general agreed with the field measurements. Model simulation indicated that the SOC content in approximately 77% of the agricultural soils in Jiangsu Province has increased since the Second National Soil Survey completed in the early 1980s. Compared with the values in 1985, the SOC content in 2000 was estimated to increase by 1.03.0 g kg 1 for the north and the coastal areas of the province, and by 3.55.0 g kg 1 for the region of Tai Lake in the south. A slight decrease (about 0.51.5 g kg 1 ) was estimated for the central region of Jiangsu Province and the Nanjing Zhenjiang hilly area. Model prediction for 2010 A.D. under two scena rios, i.e., with 30 and 50% of the harvested crop straw incorporation, suggested that the SOC in Jiangsu Province would increase, and thus that the agricultural soils would have potential as organic carbon storage. The incorporation of crop straw into soils is of great benefit to increase soil carbon storage, consequently to benefit the control of the rise of atmospheric CO 2 concentration and to maintain the sustainable development of agriculture.
文摘Finance and Marketing Department of ING Group, which is one of the largest financial group in Europe, published its Forecast Report on Chinese auto industry. The Report said that in the coming a few years, the development of China's auto industry will surpass that of Canada,
文摘When condensation occurs in supersonic flow fields, the flow is thected by the latent heat released. In the present study, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finitedifference scheme with a second-order fractionabetep for time integration. Baldwin-Lomax model, that is the algebraic model, called the zero equation model was used in the computations. The effects of initial conditions (initial degree of supersaturation and total temperature in the reservoir) on condensing fiow of moist air in a supersonic circular half nozzle were investigated. In this case, the effect of condensation on the boundary layer was also discussed in detail. As a result, the simulated flow fields were compared with experimental data in good agreement, and the velocity and temperature profiles were largely changed by condensation.
文摘Techniques using Coanda effect have been applied to the fiuid control devices. In this field, experimental studies were so far performed for the spiral jet obtained by the Coanda jet issuing from a conical cylinder with an annular slit, thrust vectoring of supersonic Coanda jets and so on. It is important from the viewpoints of effective applications to investigate the characteristics of the supersonic Coanda jet in detail. In the present study the effects of pressure ratios and nozzle configurations on the characteristics of the supersonic Coanda jet have been investigated experhoentally by a schlieren optical method and pressure measurements. Furthermore, Navier-Stokes equations were solved numerically using a 2nd-order TVD finite-volume scheme with a 3rd-rorder three stage Runge-Kutta method for time integration. k - ε model was used in the computations. The effects of initial conditions on Coandaflow were investigated numerically As a result, the simulated flow helds were compared with experimental data in good agreement qualitatively.
文摘When non-equilibrium condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, in order to control the transonic flow field with shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock / boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically and experimentally. The result obtained showed that the total pressure loss in the flow fields might be effectively reduced by the suitable combination between non-equilibrium condensation and the position of porous wall.
文摘When condensation occurs in supersonic flow fields, the flow is affected by the latent heat released, and if the heat released exceeds a certain quantity, a condensation shock wave will occur There are many papers for the passive control of shock-boundary layer interaction using the porous wall with a plenum underneath on the application of the technique to transonic airfoil flows. In the present study, this passive technique is applied to the control of a steady condensation shock wave generated in a supersonic nozzle. In order to clarify the effect of the passive shockboundary layer control on condensation shock, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration. As a result, the simulated flow fields were compared with experimental data in good agreement and the aspect of the flow field has been clarified.
文摘When condensation occurs in a supersonic flow field, the flow is affected by the latent heat released. In the present study, a condensing flow was produced by an expansion of moist air in a supersonic circular nozzle, and, by inserting a wedge-type shock generator placed in the supersonic part of the nozzle, the experimental investigations were carried out to clarify the effect of condensation on the normal shock wave and the boundary layer. As a result, the position of the shock wave relative to the condensation zone was discussed, together with the effect of condensation on pressure fiuctuations. Furthermore, a compressible viscous two-phase flow of moist air in a supersonic half nozzle was calculated to investigate the effect of condensation on boundary layer.
文摘In order to improve the performance of a Wells turbine, the effect of guide vanes with various gaps between turbine rotor and guide vane has been clarified by model testing and numerical simulation.The results have been compared with those of the case without guide vanes. It is found that the overall characteristics are considerably improved by the inlet guide vanes. Furthermore,a suitable choice of design factor for the gap has been suggested.
文摘The influences of second order Polarization Mode Dispersion (PMD) on light pulse are discussed from changing of the pulse shape and eye graph when considering second order PMD. The results by numerical simulation show that the second-order PMD components associated with depolarization of the principal states can cause significant system impairments that cause overshoot at the edge of pulse. By the same time the compensation method for second-order PMD are also discussed by theoretically and experimentally. The experiment results show that it is very effective to compensate second order PMD by using two stage PMD compensator.
文摘The total efficiency of power plants depends on the energy conversion in a combustor and a turbine .Considerably higher energy transfer rates can be obtained from a pulsed combustion.but unsteady flow of a single jet combustor reduces the turbine efficiency.Therefore.two pulse combustors were set in parallel and connected to a settling chamber that supplies a flow with constant pressure to the turbine.The aim of investigations presented here is a demonstration of technical feasibility for industrial applications and to show the benefits obtained from the pulse combustors.
文摘This paper presents the sampling and feedback control techniques, which are the kernel of our experiment on adaptive Polarization Mode Dispersion (PMD) compensation for optical fiber communication systems. Some key points on sampling and feedback techniques are discussed and practical resolutions for them are put forward.
文摘A rapid expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomena. Thereby, if the heat released by condensation of water vapour exceeds a certain quantity, the flow will become unstable and periodic flow oscillations of the unsteady condensation shock wave will occur. For the passive control of shock-boundary layer interaction using the porous wall with a plenum underneath, many papers have been presented on the application of the technique to transonic airfoil flows. In this paper, the passive technique is applied to three types of oscillations of the unsteady condensation shock wave generated in a supersonic nozzle in order to suppress the unsteady behavior As a result, the effects of number of slits and length of cavity on the aspect of flow field have been clarified numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration.
文摘A compression wave discharged from an open end of a tube causes positive impulsive noise. Active noise cancellation which is the canceling of the noise by the addition of an inverse wave is a useful technique for reducing impulsive noise. The main objective of this study is to present the design for a negative impulsive wave generator utilizing unsteady mass influx. In this paper, in order to clarify the relationship between the unsteady mass influx and the negative impulsive wave! numerical and aeroacoustic analyses have been carried out using an unsteady expansion wave discharged from an open end of a shock tube. As a result, the effect of an unsteady expansion wave on a negative impulsive wave was clarified.
