Central Asian Economies(CAEs)have diverse exchange rate policies.They have recorded higher volatility in the foreign exchange market since inception.High volatility of the transition era has drifted these economies to...Central Asian Economies(CAEs)have diverse exchange rate policies.They have recorded higher volatility in the foreign exchange market since inception.High volatility of the transition era has drifted these economies towards partial dollarization.Monetary authorities in CAEs,(already have a challenge of maintaining monetary policy autonomy)have a gigantic task of price stability and stopping the spread of dollarization.This study is directed towards assessing the drivers and the determinants of foreign exchange market pressure in CAEs.The results,based on panel data analysis and the System GMM model,have provided useful insights about the exchange market pressure determinants particularly USD,Euro,Ruble,and Renminbi.The results show that China and Russia exchange market pressure has a negative effect on the exchange market pressure of CAEs.While the dollar index shows a positive impact on the exchange market pressure of CAEs.Overall,the findings imply that China and Russia currency appreciation results in a trade deficit across CAEs.The policy implication suggests that the floating exchange rate regime(inflation targeting regime)is not in favor of CAEs,and they must use managed-float to reduce their trade deficits.展开更多
The transpiration rate of plant is physically controlled by the magnitude of the vapor pressure deficit(VPD) and stomatal conductance. A limited-transpiration trait has been reported for many crop species in differe...The transpiration rate of plant is physically controlled by the magnitude of the vapor pressure deficit(VPD) and stomatal conductance. A limited-transpiration trait has been reported for many crop species in different environments, including Maize(Zea mays L.). This trait results in restricted transpiration rate under high VPD, and can potentially conserve soil water and thus decrease soil water deficit. However, such a restriction on transpiration rate has never been explored in maize under arid climatic conditions in northwestern China. The objective of this study was to examine the transpiration rate of field-grown maize under well-watered conditions in an arid area at both leaf and whole plant levels, and therefore to investigate how transpiration rate responding to the ambient VPD at different spatial and temporal scales. The transpiration rates of maize at leaf and plant scales were measured independently using a gas exchange system and sapflow instrument, respectively. Results showed significant variations in transpiration responses of maize to VPD among different spatio-temporal scales. A two-phase transpiration response was observed at leaf level with a threshold of 3.5 k Pa while at the whole plant level, the daytime transpiration rate was positively associated with VPD across all measurement data, as was nighttime transpiration response to VPD at both leaf and whole plant level, which showed no definable threshold vapor pressure deficit, above which transpiration rate was restricted. With regard to temporal scale, transpiration was most responsive to VPD at a daily scale, moderately responsive at a half-hourly scale, and least responsive at an instantaneous scale. A similar breakpoint(about 3.0 k Pa) in response of the instantaneous leaf stomatal conductance and hourly canopy bulk conductance to VPD were also observed. At a daily scale, the maximum canopy bulk conductance occurred at a VPD about 1.7 k Pa. Generally, the responsiveness of stomatal conductance to VPD at the canopy scale was lower than that at leaf scale. These results indicate a temporal and spatial heterogeneity in how maize transpiration responses to VPD under arid climatic conditions. This could allow a better assessment of the possible benefits of using the maximum transpiration trait to improve maize drought tolerance in arid environment, and allow a better prediction of plant transpiration which underpin empirical models for stomatal conductance at different spatio-temporal scales in the arid climatic conditions.展开更多
As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results an...As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results and periodic conditions to examine around the the characteristics tube of the shell side of SWHE.Numerical simulation show that the heat transfer coefficients and initially mean increase absolute and subsequently decrease simulated 5%with heat radial angle because of the influence measured of backflow turbulent separation.nitrogen The deviation between is transfer coefficients and values for methane,drop,ethane,and are a mixture(methane/ethane)within when mean Reynolds number is over is 30000.For the pressure the simulated results values smaller than the measured values,and the absolute on deviation within 9%.Numerical simulation also tubes indicate that the pressure drop the and heat of transfer coefficients angle the shell side and of SWHE heat decrease as the winding the angle of the increases.Nusselt Considering effect winding on pressure drops transfer coefficients,modified correlations of_=0.308Re^(0.64)Pr^(0.36)(1+sin)^(1.38 )and friction factor f_=0.435Re^(-0.133)(sin)^(-0.36),are proposed.Comparing Nu number with the experimental data,the maximum deviations for heat transfer coefficients and pressure drops are less than 5%and11%respectively.展开更多
The effects of pressure and solvent on the intramolecular spin exchange of biradicals having two nitroxide fragments linked by a long flexible chain were studied by means of highpressure EPR technique.It was found tha...The effects of pressure and solvent on the intramolecular spin exchange of biradicals having two nitroxide fragments linked by a long flexible chain were studied by means of highpressure EPR technique.It was found that the intramolecular exchange interaction between nitroxides of biradical took place through the direct contact between them.By analyzing the observed EPR spectra,we have estimated the ratio(in/out)value of the average lifetime of the radical fragments inside a cage(in)to that outside the cage(out).The in/out values decreased with decreasing temperature and increasing pressure.The results suggest that the nearly cyclic conformation in a cage is favorable in solution.Further,the rotational correlation time of individual nitroxide was estimated from the anisotropic EPR signal,and the information on the segmental motion of the nitroxide group in biradical was obtained.展开更多
The present paper uses the model-dependent and the modeL independent approach to measure the RMB exchange market pressure (EMP) and the central bank's intervention using monthly data from January 1999 to June 2008....The present paper uses the model-dependent and the modeL independent approach to measure the RMB exchange market pressure (EMP) and the central bank's intervention using monthly data from January 1999 to June 2008. It is determined that the RMB has been under great appreciation pressure over the past decade. However, the pressure has been weakening since 2005. The two approaches provide significantly different results in terms of the estimated RMB EMP indices and the estimated central bank's interventions. The differences may lead to different predietions of potential currency crises. According to the estimation of the RMB EMP, and based on the model-independent approach, the paper shows that China has been under threat of an appreciation currency crisis since 2008. Therefore, China should adopt a moreflexible exchange rate regime to prevent a potential crisis.展开更多
A novel scale-up ambient pressure synthetic strategy for the preparation of imine-based covalent organic frameworks(COFs) was proposed through dynamic imine exchange reaction mechanism. The obtained COFs exhibited g...A novel scale-up ambient pressure synthetic strategy for the preparation of imine-based covalent organic frameworks(COFs) was proposed through dynamic imine exchange reaction mechanism. The obtained COFs exhibited good crystallinity and much higher porosity comparable to their solvothermally synthesized counterparts. Moreover, under ambient pressure, the COF nanofibers could readily grow on the surface of polyimide films, and the resulted nanocomposite film showed an interesting colorimetric acid-responsive behavior.展开更多
A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate ...A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure waves.The experimental and CFD results showed some slopes in the circumferential pressure distributions,and the slopes indicated the traces of specific unsteady pressure waves.Such traces varied regularly if the rotational speed varied within a range from-11%to+11%off the baseline value,but they were seriously disturbed if the rotational speed varied by-45%from the baseline value.It verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent,and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large extent.Because of the pressure wave behaviors,the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.展开更多
This paper shows that signals from the offshore China spot market for the Chinese renminbi of the Hong Kong SAR(listed as CNH)directly affect the volatility of share prices of Chinese banks and the overall risks of Ch...This paper shows that signals from the offshore China spot market for the Chinese renminbi of the Hong Kong SAR(listed as CNH)directly affect the volatility of share prices of Chinese banks and the overall risks of Chinese banking stability.This is especially so amid heightened uncertainty about global trade or the People’s Republic of China.Thus,the CNH market volatility is a leading indicator of onshore Chinese banking sector volatility.Our results suggest that further offshore exchange market movements arising out of news such as increasing trade friction with the United States will generate greater volatility in the Chinese banking sector.Far from being a shock absorber for the Chinese financial system,the CNH market appears to be a shock transmitter of risk from offshore economic policy uncertainty to the Chinese banking system.展开更多
Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves.In ground power plants,they can be used as topping devices to existing gas turbin...Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves.In ground power plants,they can be used as topping devices to existing gas turbines aiming to improve their performance characteristics.A four-port wave rotor is an attractive configuration to be integrated into the gas generator of a two-shaft gas turbine,typical for power generation and propulsion systems,by slightly modifying the architecture of existing engines.In particular,in the present article the wave rotor-topped engine utilizes the same compressor,combustion chamber and turbine inlet temperature of the baseline engine.Cycle analysis for two-shaft gas turbine engines topped with four-port wave rotors is studied and their performance at design point is compared to the performance of the baseline engines accordingly.It is concluded that important benefits are obtained with respect to the ones of the baseline engines in terms of specific work and specific fuel consumption.Furthermore calculations by varying the pressure ratio within the wave rotor and the pressure losses in the ducts connecting the wave rotor to the engine’s components indicate the effect on performance,for engines with different compressor pressure ratios and turbine inlet temperatures.展开更多
In the present paper, we estimate the de facto RMB exchange rate regime, the currency basket, the floating band and the foreign exchange market pressure before and after the reform of the Chinese exchange rate regime ...In the present paper, we estimate the de facto RMB exchange rate regime, the currency basket, the floating band and the foreign exchange market pressure before and after the reform of the Chinese exchange rate regime in 2005. We find the following stylized facts: the value of the RAIB became stable after the reform; the weight of the US dollar remained high in the basket, while other currencies remained statistically significant; and the floating band gradually increased to lO percent during 2005-2008, and then greatly narrowed from the late summer of 2008 under the assumption of a yearly resetting interval. We find that the foreign exchange market pressure increased from 2005 to 2008. A possible reason is that the weight of the US dollar in the basket was slightly lower than the share of the US dollar in total transactions on the Chinese foreign exchange market. Therefore, it is reasonable for China to adopt a dollar peg exchange rate regime.展开更多
文摘Central Asian Economies(CAEs)have diverse exchange rate policies.They have recorded higher volatility in the foreign exchange market since inception.High volatility of the transition era has drifted these economies towards partial dollarization.Monetary authorities in CAEs,(already have a challenge of maintaining monetary policy autonomy)have a gigantic task of price stability and stopping the spread of dollarization.This study is directed towards assessing the drivers and the determinants of foreign exchange market pressure in CAEs.The results,based on panel data analysis and the System GMM model,have provided useful insights about the exchange market pressure determinants particularly USD,Euro,Ruble,and Renminbi.The results show that China and Russia exchange market pressure has a negative effect on the exchange market pressure of CAEs.While the dollar index shows a positive impact on the exchange market pressure of CAEs.Overall,the findings imply that China and Russia currency appreciation results in a trade deficit across CAEs.The policy implication suggests that the floating exchange rate regime(inflation targeting regime)is not in favor of CAEs,and they must use managed-float to reduce their trade deficits.
基金funded by the National Science Fund for Distinguished Young Scholars (41125002)the Chinese National Natural Science Foundation (41271036)
文摘The transpiration rate of plant is physically controlled by the magnitude of the vapor pressure deficit(VPD) and stomatal conductance. A limited-transpiration trait has been reported for many crop species in different environments, including Maize(Zea mays L.). This trait results in restricted transpiration rate under high VPD, and can potentially conserve soil water and thus decrease soil water deficit. However, such a restriction on transpiration rate has never been explored in maize under arid climatic conditions in northwestern China. The objective of this study was to examine the transpiration rate of field-grown maize under well-watered conditions in an arid area at both leaf and whole plant levels, and therefore to investigate how transpiration rate responding to the ambient VPD at different spatial and temporal scales. The transpiration rates of maize at leaf and plant scales were measured independently using a gas exchange system and sapflow instrument, respectively. Results showed significant variations in transpiration responses of maize to VPD among different spatio-temporal scales. A two-phase transpiration response was observed at leaf level with a threshold of 3.5 k Pa while at the whole plant level, the daytime transpiration rate was positively associated with VPD across all measurement data, as was nighttime transpiration response to VPD at both leaf and whole plant level, which showed no definable threshold vapor pressure deficit, above which transpiration rate was restricted. With regard to temporal scale, transpiration was most responsive to VPD at a daily scale, moderately responsive at a half-hourly scale, and least responsive at an instantaneous scale. A similar breakpoint(about 3.0 k Pa) in response of the instantaneous leaf stomatal conductance and hourly canopy bulk conductance to VPD were also observed. At a daily scale, the maximum canopy bulk conductance occurred at a VPD about 1.7 k Pa. Generally, the responsiveness of stomatal conductance to VPD at the canopy scale was lower than that at leaf scale. These results indicate a temporal and spatial heterogeneity in how maize transpiration responses to VPD under arid climatic conditions. This could allow a better assessment of the possible benefits of using the maximum transpiration trait to improve maize drought tolerance in arid environment, and allow a better prediction of plant transpiration which underpin empirical models for stomatal conductance at different spatio-temporal scales in the arid climatic conditions.
基金supported by Beijing Natural Science Foundation(Grant No.3171002)
文摘As a critical facility,spiral-wound heat exchanger was(SWHE)has the been widely used in many industrial applications.boundary A computational fluid dynamics(CFD)model employed with smallest periodic element results and periodic conditions to examine around the the characteristics tube of the shell side of SWHE.Numerical simulation show that the heat transfer coefficients and initially mean increase absolute and subsequently decrease simulated 5%with heat radial angle because of the influence measured of backflow turbulent separation.nitrogen The deviation between is transfer coefficients and values for methane,drop,ethane,and are a mixture(methane/ethane)within when mean Reynolds number is over is 30000.For the pressure the simulated results values smaller than the measured values,and the absolute on deviation within 9%.Numerical simulation also tubes indicate that the pressure drop the and heat of transfer coefficients angle the shell side and of SWHE heat decrease as the winding the angle of the increases.Nusselt Considering effect winding on pressure drops transfer coefficients,modified correlations of_=0.308Re^(0.64)Pr^(0.36)(1+sin)^(1.38 )and friction factor f_=0.435Re^(-0.133)(sin)^(-0.36),are proposed.Comparing Nu number with the experimental data,the maximum deviations for heat transfer coefficients and pressure drops are less than 5%and11%respectively.
文摘The effects of pressure and solvent on the intramolecular spin exchange of biradicals having two nitroxide fragments linked by a long flexible chain were studied by means of highpressure EPR technique.It was found that the intramolecular exchange interaction between nitroxides of biradical took place through the direct contact between them.By analyzing the observed EPR spectra,we have estimated the ratio(in/out)value of the average lifetime of the radical fragments inside a cage(in)to that outside the cage(out).The in/out values decreased with decreasing temperature and increasing pressure.The results suggest that the nearly cyclic conformation in a cage is favorable in solution.Further,the rotational correlation time of individual nitroxide was estimated from the anisotropic EPR signal,and the information on the segmental motion of the nitroxide group in biradical was obtained.
文摘The present paper uses the model-dependent and the modeL independent approach to measure the RMB exchange market pressure (EMP) and the central bank's intervention using monthly data from January 1999 to June 2008. It is determined that the RMB has been under great appreciation pressure over the past decade. However, the pressure has been weakening since 2005. The two approaches provide significantly different results in terms of the estimated RMB EMP indices and the estimated central bank's interventions. The differences may lead to different predietions of potential currency crises. According to the estimation of the RMB EMP, and based on the model-independent approach, the paper shows that China has been under threat of an appreciation currency crisis since 2008. Therefore, China should adopt a moreflexible exchange rate regime to prevent a potential crisis.
基金financially supported by the National Natural Science Foundation of China (Nos. 21174089, 21674068 and 51633004)
文摘A novel scale-up ambient pressure synthetic strategy for the preparation of imine-based covalent organic frameworks(COFs) was proposed through dynamic imine exchange reaction mechanism. The obtained COFs exhibited good crystallinity and much higher porosity comparable to their solvothermally synthesized counterparts. Moreover, under ambient pressure, the COF nanofibers could readily grow on the surface of polyimide films, and the resulted nanocomposite film showed an interesting colorimetric acid-responsive behavior.
基金co-supported by the National Natural Science Foundation of China(No.51906007)the National Key Laboratory Foundation of China(No.6142702190204)。
文摘A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure waves.The experimental and CFD results showed some slopes in the circumferential pressure distributions,and the slopes indicated the traces of specific unsteady pressure waves.Such traces varied regularly if the rotational speed varied within a range from-11%to+11%off the baseline value,but they were seriously disturbed if the rotational speed varied by-45%from the baseline value.It verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent,and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large extent.Because of the pressure wave behaviors,the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.
文摘This paper shows that signals from the offshore China spot market for the Chinese renminbi of the Hong Kong SAR(listed as CNH)directly affect the volatility of share prices of Chinese banks and the overall risks of Chinese banking stability.This is especially so amid heightened uncertainty about global trade or the People’s Republic of China.Thus,the CNH market volatility is a leading indicator of onshore Chinese banking sector volatility.Our results suggest that further offshore exchange market movements arising out of news such as increasing trade friction with the United States will generate greater volatility in the Chinese banking sector.Far from being a shock absorber for the Chinese financial system,the CNH market appears to be a shock transmitter of risk from offshore economic policy uncertainty to the Chinese banking system.
文摘Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves.In ground power plants,they can be used as topping devices to existing gas turbines aiming to improve their performance characteristics.A four-port wave rotor is an attractive configuration to be integrated into the gas generator of a two-shaft gas turbine,typical for power generation and propulsion systems,by slightly modifying the architecture of existing engines.In particular,in the present article the wave rotor-topped engine utilizes the same compressor,combustion chamber and turbine inlet temperature of the baseline engine.Cycle analysis for two-shaft gas turbine engines topped with four-port wave rotors is studied and their performance at design point is compared to the performance of the baseline engines accordingly.It is concluded that important benefits are obtained with respect to the ones of the baseline engines in terms of specific work and specific fuel consumption.Furthermore calculations by varying the pressure ratio within the wave rotor and the pressure losses in the ducts connecting the wave rotor to the engine’s components indicate the effect on performance,for engines with different compressor pressure ratios and turbine inlet temperatures.
文摘In the present paper, we estimate the de facto RMB exchange rate regime, the currency basket, the floating band and the foreign exchange market pressure before and after the reform of the Chinese exchange rate regime in 2005. We find the following stylized facts: the value of the RAIB became stable after the reform; the weight of the US dollar remained high in the basket, while other currencies remained statistically significant; and the floating band gradually increased to lO percent during 2005-2008, and then greatly narrowed from the late summer of 2008 under the assumption of a yearly resetting interval. We find that the foreign exchange market pressure increased from 2005 to 2008. A possible reason is that the weight of the US dollar in the basket was slightly lower than the share of the US dollar in total transactions on the Chinese foreign exchange market. Therefore, it is reasonable for China to adopt a dollar peg exchange rate regime.