There are numerous studies comparing different kinds of environmental taxes and standards.However,forms of environmental standards focused by former researchers are usually quantitybased limits/standards(e.g.pounds pe...There are numerous studies comparing different kinds of environmental taxes and standards.However,forms of environmental standards focused by former researchers are usually quantitybased limits/standards(e.g.pounds per day or pounds per unit of output).Concentration-based emission standard(e.g.milligrams per liter of wastewater) as one important form of environmental standard has not been given much attention.In this article,comparable estimates of their probable effect on enterprise pollution reduction will be developed for concentrationbased effluent standards,effluent taxes,and a combination of both.A linear simulation model is used to clearly and obviously compare the effects of effluent taxes and concentration-based standards within the same figure.With one detailed application to the paper industry,some enlightenment and conclusions-as well as the general applicability of these principles-are then provided:Under the same effluent tax rate,enterprises,groups,and industries that are cleaner will reduce more pollutants than those that have higher pollutant abatement costs.It is recommended that effluent taxes are set by avoiding cutting it even at one stroke and considering the feasibility of pollution-reducing technology in various industries.It is necessary to reduce MAC of enterprises to better stimulate enterprises' or industries' emission reduction by preferential measures,such as high tax rate coordinated by speeding up the depreciation of environmental protection equipment.展开更多
Insufficient assessment of emission reduction effects still exists in the carbon emission rights trading system,a major environmental regulation measure in China.Based on the data from the carbon trading pilot coverin...Insufficient assessment of emission reduction effects still exists in the carbon emission rights trading system,a major environmental regulation measure in China.Based on the data from the carbon trading pilot covering the years from 2007 to 2017,this study combined the synthetic control method with dynamic spatial Durbin model to comprehensively evaluate the spatial emission reduction effects of carbon trading policies.The results showed that:①The carbon trading policies promoted carbon emission reductions in the pilot regions,among which Tianjin and Hubei responded significantly,and also helped to suppress carbon emissions in the neighboring areas.②Long-term emission reduction effect from carbon emissions trading became gradually significant,while the indirect emission reduction effect was relatively weaker.③In term of reducing carbon emissions,the economic development channel played a key role,but it had a threat to the promotion of carbon emissions in the surrounding areas.Energy consumption was the main obstacle to the growth of carbon emissions.④In the long run,technological progress tended to become the key to the effective implementation of potential emission reduction effects of carbon trading policies.Based on the above findings,we suggest that the construction of a national carbon trading market should be promoted,the balanced development and orderly advancement of regional carbon trading markets should be paid attention to,the coordinated development of green economy as well as knowledge and technology exchange and cooperation among regions should be strengthened to form a low carbon development model among regions.展开更多
The Chinese approach to poverty reduction is a government-led and marketbased approach that gives priority to infrastructure and combines fiscal subsidy with development as an antidote to poverty.These characteristics...The Chinese approach to poverty reduction is a government-led and marketbased approach that gives priority to infrastructure and combines fiscal subsidy with development as an antidote to poverty.These characteristics are also evident in China’s cooperation with other developing countries on poverty reduction.China supports other developing countries to reduce poverty via aid and investment mainly in the field of infrastructure.While the government and SOEs take the lead in foreign aid and investment,China also invites other sources of capital to participate in market-based development in partnership with recipient countries.Our empirical research finds that aid and investment from China are generally conducive to reducing poverty incidence in recipient developing countries,but their poverty reduction effects vary across different types of aid and investment.The elements characteristic of the Chinese approach to poverty reduction proved to be effective in helping other developing countries reduce poverty as well.Nevertheless,the effectiveness of aid and investment in reducing poverty is subject to the governance and market efficiency of recipient countries.In order for the Chinese experience to work in less developed countries,future cooperation on poverty reduction must put a premium on governance and market systems.展开更多
The effective recovery of water level is a crucial measure of the success of comprehensive groundwater over-exploitation management actions in North China.However,traditional evaluation method do not directly capture ...The effective recovery of water level is a crucial measure of the success of comprehensive groundwater over-exploitation management actions in North China.However,traditional evaluation method do not directly capture the relationship between mining and other equilibrium elements.This study presents an innovative evaluation method to assess the water level recovery resulting from mining reduction based on the relationship between variation in exploitation and recharge.Firstly,the recharge variability of source and sink terms for both the base year and evaluation year is calculated and the coefficient of recharge variationβis introduced,which is then used to calculate the effective mining reduction and solve the water level recovery value caused by the effective mining reduction,and finally the water level recovery contribution by mining reduction is calculated by combining with the actual volume of mining reduction in the evaluation area.This research focuses on Baoding and Shijiazhuang Plain area,which share similar hydrogeological conditions but vary in groundwater exploitation and utilization.As the effect of groundwater level recovery with mining reduction was evaluated in these two areas as case study.In 2018,the results showed an effective water level recovery of 0.17 m and 0.13 m in the shallow groundwater of Shijiazhuang and Baoding Plain areas,respectively.The contributions of recovery from mining reduction were 76%and 57.98%for these two areas,respectively.It was notable that the water level recovery was most prominent in the foothill plain regions.From the evaluation results,it is evident that water level recovery depends not only on the intensity of groundwater mining reduction,but also on its effectiveness.The value of water level recovery alone cannot accurately indicate the intensity of mining reduction,as recharge variation significantly influences water level changes.Therefore,in practice,it is crucial to comprehensively assess the impact of mining reduction on water level recovery by combining the coefficient of recharge variation with the contribution of water level recovery from mining reduction.This integrated approach provide a more reasonable and scientifically supported basis,offering essential data support for groundwater management and conservation.To improve the accuracy and reliability of evaluation results,future work will focus on the standardizing and normalizing raw data processing.展开更多
This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the wind tunnel test condition. In order to analyze the changes in the performance due ...This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the wind tunnel test condition. In order to analyze the changes in the performance due to the inclusion of a serrated trailing edge designed to reduce noise, a 10 k W wind turbine rotor was equipped with a thin serrated trailing edge. The restrictive condition for the serrated trailing edge equipped with the using of a 2D airfoil was examined through the using of a wind tunnel experiment after studying existing restrictive condition and analyzing prior research on serrated trailing edges. The aerodynamic performance and noise reduction effect of a small-scale model were investigated with the using of a serrated trailing edge. Moreover, the noise levels from the experiment were considered that the noise prediction method could be used for a full-scale rotor. It is confirmed that noise reduction effect is compared with wind tunnel test data at the 2D airfoil and model rotor condition.展开更多
Wind speed distribution regularities in a shelter mesh (S. M.) have been deduced from the wind speed distribution in the sheltered area of a single shelter beh (S. B.).The components of a wind vector in a mesh follow ...Wind speed distribution regularities in a shelter mesh (S. M.) have been deduced from the wind speed distribution in the sheltered area of a single shelter beh (S. B.).The components of a wind vector in a mesh follow the error function distribution model or the logarithmic model of 2-variable power function.The wind vector itself follows the vector composition model of these models.We can calculate the wind speed distribution and wind reduction effect of a mesh under the conditions of any shelter-belt characteristics, any size and shape of a mesh and any wind inclination angle with this model. The results of our field model experiment are in better agreement with the theoretically calculated results.展开更多
In this particular study,99 typical managed small watersheds which representing five water erosion areas in China were selected to study zonality of Runoff Reduction Efficiency(RRE)and of Sediment Reduction Efficiency...In this particular study,99 typical managed small watersheds which representing five water erosion areas in China were selected to study zonality of Runoff Reduction Efficiency(RRE)and of Sediment Reduction Efficiency(SRE).The RRE is the ratio of Effect of Runoff Reduction(ERR)by soil and water conservation measure over management degree in a watershed.And The SRE is the ratio of Effect of Sediment Reduction(ESR)by soil and water conservation measure over management degree in a watershed.First of ah,statistical analysis was applied to test the zonal effects of RRE and SRE between different water erosion regions.The results showed that the mean RRE values in northern regions were significantly greater than those of southern regions;and the mean SRE values in northern regions were significantly greater than those in southern regions.Next,the variation of RRE with runoff depth(H)was studied in direction of both latitude and longitude across regions influenced by East Asian Monsoon.Meanwhile,the variation of SRE with specific sediment yield(Y)was studied in direction of both latitude and longitude across regions influenced by East Asian Monsoon.The results showed that RRE had the inverse variation trend as H in both latitude and longitude direction and SRE had the same variation trend as Y in both latitude and longitude direction.Furthermore,the variation of unit management area Runoff Reduction Rate(RRR)with H and RRE was studied in direction of both latitude and longitude.And the variation of unit management area Sediment Reduction Rate(SRR)with Y and SRE was studied in direction of both latitude and longitude.It was found that RRR had the similar variation trend as H in latitude direction and there was critical point around 37°N greater than which RRR began to be equal to H or even larger;RRR had the similar variation trend as H in longitude direction and there was a critical point around 109°E lees than which RRR began to equal to or greater than H;SRR had the similar variation trend as Y in latitude direction and there was critical point around 36°N greater than which SRR began to be equal to Y or even larger;SRR had the similar variation trend as Y in longitude direction and there was a critical point around 106°E lees than which SRR began to equal to or greater than Y.The zonality of RRE,RRR,SRE and SRR was determined by the combined influence of climate variation and special landform in regions controlled by East Asian Monsoon in China.展开更多
Objective To evaluate the effects of lung volume reduction surgery (LVRS) on early lung function and pulmonary hemodynamics in severe chronic obstructive pulmonary disease (COPD). Methods 31 patients with severe COPD ...Objective To evaluate the effects of lung volume reduction surgery (LVRS) on early lung function and pulmonary hemodynamics in severe chronic obstructive pulmonary disease (COPD). Methods 31 patients with severe COPD underwent LVRS, bilateral LVRS in 11 patients and unilateral in 20 patients. The results of lung function (FEV1, RV, TLC), arterial blood gas analysis (PAO2, PACO2 ) and color Doppler echocardiography (CD,CI,FS,EF,PAP) were analyzed before and 3 month after LVRS in 26 cases. Results FEV1, RV and TLC were improved significantly after surgery ( P 【 0. 01). PaO2 increased (P 【 0. 05 ) and PaCO2, decreased postoperatively (P 【 0. 01). According to the Doppler echocardiography, there were no statistic differences in cardiac functions (CO, CI, FS, EF, and PAP) between pre- and post-operation. The 6-minute-walk-distance in 26 patients was (227 ± 88) m, significantly increased after surgery. Conclusion LVRS is effective in the treatment of patients with severe COPD. 3 months after operation, the展开更多
The surrounding rock of underground space is always affected by external dynamic disturbance from the side position,such as blasting vibration from a stope at the same level or seismic waves from adjacent strata.A ser...The surrounding rock of underground space is always affected by external dynamic disturbance from the side position,such as blasting vibration from a stope at the same level or seismic waves from adjacent strata.A series of laboratory tests,numerical simulations and theoretical analyses were carried out in this study to disclose the sliding mechanism of roof rock blocks under lateral disturbance.Firstly,the experiments on trapezoidal key block under various clamping loads and disturbance were conducted,followed by numerical simulations using the fast Lagrangian analysis of continua(FLAC3D).Then,based on the conventional wave propagation model and the classical shear-slip constitutive model,a theoretical model was proposed to capture the relative displacement between blocks and the sliding displacement of the key block.The results indicate that the sliding displacement of the key block increased linearly with the disturbance energy and decreased exponentially with the clamping load when the key block was disturbed to slide(without instability).Meanwhile,when the key block was disturbed to fall,two types of instability process may appear as immediate type or delayed type.In addition,the propagation of stress waves in the block system exhibited obvious low-velocity and lowfrequency characteristics,resulting in the friction reduction effect appearing at the contact interface,which is the essential reason for the sliding of rock blocks.The results can be applied to practical underground engineering and provide valuable guidance for the early detection and prevention of rockfalling disasters.展开更多
A field experiment was carried out in Cd-contaminated rice fields in a county of Hengyang to explore the effects of different types of remediation agents on the contents of soil available Cd and rice Cd,and rice yield...A field experiment was carried out in Cd-contaminated rice fields in a county of Hengyang to explore the effects of different types of remediation agents on the contents of soil available Cd and rice Cd,and rice yield by using one rice variety Longliangyouhuazhan,and 4 kinds of remediation agents:DG foliar control agent,SMA microbial inoculant,XFJ organic fertilizer and LXM calcium-and silicon-based passivator as test materials.The results showed that compared with CK,after applying DG foliar control agent,soil available Cd content increased rather than decreased,whereas rice Cd content decreased,not reaching a significant level.When applied with SMA microbial inoculant,soil pH value,soil available Cd and rice Cd contents showed a downward then upward trend with the increase of its application rates.Between 3 levels of SMA treatments,the content of soil available Cd in SMA2 was the lowest,decreased by 8.59%in comparison with CK,contrarily,two other SMA treatments were increasing instead of decreasing in the content of soil available Cd.The application of XFJ organic fertilizer and LXM calcium-and silicon-based passivator increased soil pH value,and reduced soil available Cd and rice Cd contents;the contents of soil available Cd and rice Cd decreased with their application rates increasing.Compared with CK,XFJ3 reduced soil available Cd content by 9.40%,and significantly reduced rice Cd content by 57.28%.In LXM3 treatment,soil available Cd content reduced by 14.57%,rice Cd content was 71.57%lower than CK,reaching the lowest level.In general,LXM calcium-and silicon-based passivator had the best Cd reduction effect,with the optimal application amount of 6000 kg/hm^(2).展开更多
Through pot tests of early rice and late rice in Cd polluted environment(soil Cd content,1.0 mg/kg),the inhibition and control effects of single application of organic fertilizers involving pig manure and biochar,and ...Through pot tests of early rice and late rice in Cd polluted environment(soil Cd content,1.0 mg/kg),the inhibition and control effects of single application of organic fertilizers involving pig manure and biochar,and their combined application with alkaline amendments involving lime and oyster shell powder on soil Cd activation and rice Cd absorption were compared.And the correlation between soil available Cd and rice grain Cd was discussed.The results showed that compared with CK which did not involve amendments,the grain yields of early rice and late rice increased by 15.52%~36.01%and 12.02%~27.28%,respectively,the grain Cd content decreased by 24.76%~64.53%and 4.93%~58.32%,respectively,and the grain Cd accumulation decreased by 22.27%~51.76%and 33.84%~46.95%,respectively,except for single pig manure treatment.In particular,the Cd reduction effect of biochar was significantly better than that of pig manure,and the combined application with oyster shell powder was better than that with lime;after the harvest of early and late rice,the available Cd content in soil applied with amendments decreased by 35.00%~65.88%and 30.93%~68.57%,respectively,compared with CK.Further analysis showed that the soil available Cd content and rice grain Cd content could fit the linear equation well(R2>0.70,P<0.05),which demonstrated that the combined application of organic fertilizers and alkaline amendments can quickly reduce the Cd content of rice grain by passivating soil available Cd,and the combined application between biochar and oyster shell powder had a better effect.展开更多
Groundwater over-exploitation is a major problem in groundwater development, utilization and protection. At present, the area of shallow groundwater over-exploitation in the High-tech Zone is 76 km^(2). In this study,...Groundwater over-exploitation is a major problem in groundwater development, utilization and protection. At present, the area of shallow groundwater over-exploitation in the High-tech Zone is 76 km^(2). In this study, the system and mechanism construction, engineering measure construction, and control effect of national comprehensive control project of groundwater over-exploitation areas in the High-tech Zone in 2020 were evaluated, and the comprehensive control of groundwater over-exploitation in the High-tech Zone in the year was summarized to provide effective basis for the continuous implementation of comprehensive control of groundwater over-exploitation. At the same time, the water-saving and exploitation reduction effect and generalizability of different measures were studied to provide useful reference for other over-exploitation areas.展开更多
Optoelectronic imaging equipment is easy to expose to active laser detection devices because of ＂cat eye＂ effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a ...Optoelectronic imaging equipment is easy to expose to active laser detection devices because of ＂cat eye＂ effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a cat eye target. Decentered field lens structure is adopted in the design without sacrificing imaging quality and clear aperture. An imaging system with±30° field of view is taken for example. The detailed design and simulation results are presented. The results indicate that this kind of optical system can reduce the retroreflection signal substantially and maintain acceptable imaging performance.展开更多
With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Zeng Jie(曾杰)and Prof.Yang Jinlong(杨金龙),both from Hefei National Laboratory for Physica...With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Zeng Jie(曾杰)and Prof.Yang Jinlong(杨金龙),both from Hefei National Laboratory for Physical Sciences at the Microscale,University of Science and Technology of China,展开更多
Greenhouse gas emissions are increas- ing every year and their effect on the environment is becoming increasingly serious. In 2009, the concen- tration of carbon dioxide in the earth＇s atmosphere reached 387 μL/L, t...Greenhouse gas emissions are increas- ing every year and their effect on the environment is becoming increasingly serious. In 2009, the concen- tration of carbon dioxide in the earth＇s atmosphere reached 387 μL/L, the highest level in recorded histo- ry. This paper summarizes the global carbon emission situation, sources of greenhouse gases, and the con-tribution of agriculture to the accumutauon ot green- house gases. Several scientific measures are proposed to reduce greenhouse gas emissions resulting from ru- minant production such as improving animal perform- ance, regulating the rumen environment, and reduc- ing the amount of greenhouse gases emitted from live- stock manure.展开更多
The traditional Chinese medicine Aconm Lateralis Radix Praeparaia(Fuzi)is pungent and sweet in taste,hot in nature,and has high toxicity.It governs the meridians of the heart,kidney and spleen.It has the functions of ...The traditional Chinese medicine Aconm Lateralis Radix Praeparaia(Fuzi)is pungent and sweet in taste,hot in nature,and has high toxicity.It governs the meridians of the heart,kidney and spleen.It has the functions of restoring yang to save from collapse,dispersing cold and removing dampness,and warming the middle to relieve pain.It is often used for the treatment of yang collapse,cold limbs,weak pulse,heart yang deficiency,heart pain due to chest impediment,abdominal cold-pain,kidney yang deficiency,impotence and cold in womb,and syndrome of exogenous disease due to yang deficiency,etc.Its great yang qi and strong medicinal properties often bring about toxic and adverse effects.However,after processing or combination with other medicinal materials,the effects of Aconm Lateralis Radix Praeparaia are quite different.Not only the toxicity is greatly reduced,but also the curative effects are strengthened.Through searching related literature,this paper reviewed the researches about the toxicity reduction and curative effect improvement of Aconm Lateralis Radix Praeparaia,in order to provide a certain theoretic reference for future further research of Aconm Lateralis Radix Praeparaia.展开更多
The oxygen reduction kinetics on polycobaltprotoporphyrin(PCoPP)film has been examined with the rotating disc electrode technique in O_2-saturated solution of various pH.PCoPP film promotes the oxygen reduction proces...The oxygen reduction kinetics on polycobaltprotoporphyrin(PCoPP)film has been examined with the rotating disc electrode technique in O_2-saturated solution of various pH.PCoPP film promotes the oxygen reduction process via two electrons to produce peroxide over wide pH range. When pH value of solution decreases,catalytic activity of PCoPP film increases.Possible catalytic mechanisms have been proposed for oxygen reduction.展开更多
In order to develop technologies of friction drag reduction with a flexible tube to be used for water transport, experimental studies were carried out on the influence of Young’s modulus on the turbulent drag reducti...In order to develop technologies of friction drag reduction with a flexible tube to be used for water transport, experimental studies were carried out on the influence of Young’s modulus on the turbulent drag reduction. The friction coefficients of flexible tubes with different Young’s modulus were examined by using a sleeve-tube structure. The fluctuating vibration of the outer wall and the fluctuating pressure on the inner wall of the tubes were measured with a laser displacement sensor and a pressure sensor. The results are as follows. The smaller the Young’s modulus of a flexible tube and the larger the Reynolds number, the larger the turbulent drag reduction rates become. The transition from laminar flow to turbulent flow can be delayed with an appropriate Young’s modulus. Non-dimensional amplitude of fluctuating vibration on the outer wall is smaller than that of a viscous sub-layer thickness, and is positively correlated with the friction drag reduction.展开更多
基金supported by Beijing Natural Science Foundation(9154036)"Water Pollution Control Strategy and Decision Support Platform"[grant No.2009ZX07631-02-03]"Water Pollution Accident Damage Assessment Technology Research[grant No.201309060]"
文摘There are numerous studies comparing different kinds of environmental taxes and standards.However,forms of environmental standards focused by former researchers are usually quantitybased limits/standards(e.g.pounds per day or pounds per unit of output).Concentration-based emission standard(e.g.milligrams per liter of wastewater) as one important form of environmental standard has not been given much attention.In this article,comparable estimates of their probable effect on enterprise pollution reduction will be developed for concentrationbased effluent standards,effluent taxes,and a combination of both.A linear simulation model is used to clearly and obviously compare the effects of effluent taxes and concentration-based standards within the same figure.With one detailed application to the paper industry,some enlightenment and conclusions-as well as the general applicability of these principles-are then provided:Under the same effluent tax rate,enterprises,groups,and industries that are cleaner will reduce more pollutants than those that have higher pollutant abatement costs.It is recommended that effluent taxes are set by avoiding cutting it even at one stroke and considering the feasibility of pollution-reducing technology in various industries.It is necessary to reduce MAC of enterprises to better stimulate enterprises' or industries' emission reduction by preferential measures,such as high tax rate coordinated by speeding up the depreciation of environmental protection equipment.
文摘Insufficient assessment of emission reduction effects still exists in the carbon emission rights trading system,a major environmental regulation measure in China.Based on the data from the carbon trading pilot covering the years from 2007 to 2017,this study combined the synthetic control method with dynamic spatial Durbin model to comprehensively evaluate the spatial emission reduction effects of carbon trading policies.The results showed that:①The carbon trading policies promoted carbon emission reductions in the pilot regions,among which Tianjin and Hubei responded significantly,and also helped to suppress carbon emissions in the neighboring areas.②Long-term emission reduction effect from carbon emissions trading became gradually significant,while the indirect emission reduction effect was relatively weaker.③In term of reducing carbon emissions,the economic development channel played a key role,but it had a threat to the promotion of carbon emissions in the surrounding areas.Energy consumption was the main obstacle to the growth of carbon emissions.④In the long run,technological progress tended to become the key to the effective implementation of potential emission reduction effects of carbon trading policies.Based on the above findings,we suggest that the construction of a national carbon trading market should be promoted,the balanced development and orderly advancement of regional carbon trading markets should be paid attention to,the coordinated development of green economy as well as knowledge and technology exchange and cooperation among regions should be strengthened to form a low carbon development model among regions.
文摘The Chinese approach to poverty reduction is a government-led and marketbased approach that gives priority to infrastructure and combines fiscal subsidy with development as an antidote to poverty.These characteristics are also evident in China’s cooperation with other developing countries on poverty reduction.China supports other developing countries to reduce poverty via aid and investment mainly in the field of infrastructure.While the government and SOEs take the lead in foreign aid and investment,China also invites other sources of capital to participate in market-based development in partnership with recipient countries.Our empirical research finds that aid and investment from China are generally conducive to reducing poverty incidence in recipient developing countries,but their poverty reduction effects vary across different types of aid and investment.The elements characteristic of the Chinese approach to poverty reduction proved to be effective in helping other developing countries reduce poverty as well.Nevertheless,the effectiveness of aid and investment in reducing poverty is subject to the governance and market efficiency of recipient countries.In order for the Chinese experience to work in less developed countries,future cooperation on poverty reduction must put a premium on governance and market systems.
基金supported by National Natural Science Foundation of China(41972262)Hebei Natural Science Foundation for Excellent Young Scholars(D2020504032).
文摘The effective recovery of water level is a crucial measure of the success of comprehensive groundwater over-exploitation management actions in North China.However,traditional evaluation method do not directly capture the relationship between mining and other equilibrium elements.This study presents an innovative evaluation method to assess the water level recovery resulting from mining reduction based on the relationship between variation in exploitation and recharge.Firstly,the recharge variability of source and sink terms for both the base year and evaluation year is calculated and the coefficient of recharge variationβis introduced,which is then used to calculate the effective mining reduction and solve the water level recovery value caused by the effective mining reduction,and finally the water level recovery contribution by mining reduction is calculated by combining with the actual volume of mining reduction in the evaluation area.This research focuses on Baoding and Shijiazhuang Plain area,which share similar hydrogeological conditions but vary in groundwater exploitation and utilization.As the effect of groundwater level recovery with mining reduction was evaluated in these two areas as case study.In 2018,the results showed an effective water level recovery of 0.17 m and 0.13 m in the shallow groundwater of Shijiazhuang and Baoding Plain areas,respectively.The contributions of recovery from mining reduction were 76%and 57.98%for these two areas,respectively.It was notable that the water level recovery was most prominent in the foothill plain regions.From the evaluation results,it is evident that water level recovery depends not only on the intensity of groundwater mining reduction,but also on its effectiveness.The value of water level recovery alone cannot accurately indicate the intensity of mining reduction,as recharge variation significantly influences water level changes.Therefore,in practice,it is crucial to comprehensively assess the impact of mining reduction on water level recovery by combining the coefficient of recharge variation with the contribution of water level recovery from mining reduction.This integrated approach provide a more reasonable and scientifically supported basis,offering essential data support for groundwater management and conservation.To improve the accuracy and reliability of evaluation results,future work will focus on the standardizing and normalizing raw data processing.
基金supported by the Research Fund of 2014 Chungnam National University of the Korea
文摘This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the wind tunnel test condition. In order to analyze the changes in the performance due to the inclusion of a serrated trailing edge designed to reduce noise, a 10 k W wind turbine rotor was equipped with a thin serrated trailing edge. The restrictive condition for the serrated trailing edge equipped with the using of a 2D airfoil was examined through the using of a wind tunnel experiment after studying existing restrictive condition and analyzing prior research on serrated trailing edges. The aerodynamic performance and noise reduction effect of a small-scale model were investigated with the using of a serrated trailing edge. Moreover, the noise levels from the experiment were considered that the noise prediction method could be used for a full-scale rotor. It is confirmed that noise reduction effect is compared with wind tunnel test data at the 2D airfoil and model rotor condition.
文摘Wind speed distribution regularities in a shelter mesh (S. M.) have been deduced from the wind speed distribution in the sheltered area of a single shelter beh (S. B.).The components of a wind vector in a mesh follow the error function distribution model or the logarithmic model of 2-variable power function.The wind vector itself follows the vector composition model of these models.We can calculate the wind speed distribution and wind reduction effect of a mesh under the conditions of any shelter-belt characteristics, any size and shape of a mesh and any wind inclination angle with this model. The results of our field model experiment are in better agreement with the theoretically calculated results.
基金Financial support was provided by the National Natural Science Foundation of China(Grant No.41271304,Grant No.41001165)Open Foundation of State Key Laboratory of Soil Erosion and Dryland Farming on Loees Plateau(K318009902-1315).
文摘In this particular study,99 typical managed small watersheds which representing five water erosion areas in China were selected to study zonality of Runoff Reduction Efficiency(RRE)and of Sediment Reduction Efficiency(SRE).The RRE is the ratio of Effect of Runoff Reduction(ERR)by soil and water conservation measure over management degree in a watershed.And The SRE is the ratio of Effect of Sediment Reduction(ESR)by soil and water conservation measure over management degree in a watershed.First of ah,statistical analysis was applied to test the zonal effects of RRE and SRE between different water erosion regions.The results showed that the mean RRE values in northern regions were significantly greater than those of southern regions;and the mean SRE values in northern regions were significantly greater than those in southern regions.Next,the variation of RRE with runoff depth(H)was studied in direction of both latitude and longitude across regions influenced by East Asian Monsoon.Meanwhile,the variation of SRE with specific sediment yield(Y)was studied in direction of both latitude and longitude across regions influenced by East Asian Monsoon.The results showed that RRE had the inverse variation trend as H in both latitude and longitude direction and SRE had the same variation trend as Y in both latitude and longitude direction.Furthermore,the variation of unit management area Runoff Reduction Rate(RRR)with H and RRE was studied in direction of both latitude and longitude.And the variation of unit management area Sediment Reduction Rate(SRR)with Y and SRE was studied in direction of both latitude and longitude.It was found that RRR had the similar variation trend as H in latitude direction and there was critical point around 37°N greater than which RRR began to be equal to H or even larger;RRR had the similar variation trend as H in longitude direction and there was a critical point around 109°E lees than which RRR began to equal to or greater than H;SRR had the similar variation trend as Y in latitude direction and there was critical point around 36°N greater than which SRR began to be equal to Y or even larger;SRR had the similar variation trend as Y in longitude direction and there was a critical point around 106°E lees than which SRR began to equal to or greater than Y.The zonality of RRE,RRR,SRE and SRR was determined by the combined influence of climate variation and special landform in regions controlled by East Asian Monsoon in China.
文摘Objective To evaluate the effects of lung volume reduction surgery (LVRS) on early lung function and pulmonary hemodynamics in severe chronic obstructive pulmonary disease (COPD). Methods 31 patients with severe COPD underwent LVRS, bilateral LVRS in 11 patients and unilateral in 20 patients. The results of lung function (FEV1, RV, TLC), arterial blood gas analysis (PAO2, PACO2 ) and color Doppler echocardiography (CD,CI,FS,EF,PAP) were analyzed before and 3 month after LVRS in 26 cases. Results FEV1, RV and TLC were improved significantly after surgery ( P 【 0. 01). PaO2 increased (P 【 0. 05 ) and PaCO2, decreased postoperatively (P 【 0. 01). According to the Doppler echocardiography, there were no statistic differences in cardiac functions (CO, CI, FS, EF, and PAP) between pre- and post-operation. The 6-minute-walk-distance in 26 patients was (227 ± 88) m, significantly increased after surgery. Conclusion LVRS is effective in the treatment of patients with severe COPD. 3 months after operation, the
基金This work was financially supported by National Key Research and Development Program of China(Grant No.2022YFC2903903)National Natural Science Foundation of China(Grant No.52304132)Yunnan Major Scientific and Technological Projects(Grant No.202202AG050014).These support is gratefully acknowledged.
文摘The surrounding rock of underground space is always affected by external dynamic disturbance from the side position,such as blasting vibration from a stope at the same level or seismic waves from adjacent strata.A series of laboratory tests,numerical simulations and theoretical analyses were carried out in this study to disclose the sliding mechanism of roof rock blocks under lateral disturbance.Firstly,the experiments on trapezoidal key block under various clamping loads and disturbance were conducted,followed by numerical simulations using the fast Lagrangian analysis of continua(FLAC3D).Then,based on the conventional wave propagation model and the classical shear-slip constitutive model,a theoretical model was proposed to capture the relative displacement between blocks and the sliding displacement of the key block.The results indicate that the sliding displacement of the key block increased linearly with the disturbance energy and decreased exponentially with the clamping load when the key block was disturbed to slide(without instability).Meanwhile,when the key block was disturbed to fall,two types of instability process may appear as immediate type or delayed type.In addition,the propagation of stress waves in the block system exhibited obvious low-velocity and lowfrequency characteristics,resulting in the friction reduction effect appearing at the contact interface,which is the essential reason for the sliding of rock blocks.The results can be applied to practical underground engineering and provide valuable guidance for the early detection and prevention of rockfalling disasters.
文摘A field experiment was carried out in Cd-contaminated rice fields in a county of Hengyang to explore the effects of different types of remediation agents on the contents of soil available Cd and rice Cd,and rice yield by using one rice variety Longliangyouhuazhan,and 4 kinds of remediation agents:DG foliar control agent,SMA microbial inoculant,XFJ organic fertilizer and LXM calcium-and silicon-based passivator as test materials.The results showed that compared with CK,after applying DG foliar control agent,soil available Cd content increased rather than decreased,whereas rice Cd content decreased,not reaching a significant level.When applied with SMA microbial inoculant,soil pH value,soil available Cd and rice Cd contents showed a downward then upward trend with the increase of its application rates.Between 3 levels of SMA treatments,the content of soil available Cd in SMA2 was the lowest,decreased by 8.59%in comparison with CK,contrarily,two other SMA treatments were increasing instead of decreasing in the content of soil available Cd.The application of XFJ organic fertilizer and LXM calcium-and silicon-based passivator increased soil pH value,and reduced soil available Cd and rice Cd contents;the contents of soil available Cd and rice Cd decreased with their application rates increasing.Compared with CK,XFJ3 reduced soil available Cd content by 9.40%,and significantly reduced rice Cd content by 57.28%.In LXM3 treatment,soil available Cd content reduced by 14.57%,rice Cd content was 71.57%lower than CK,reaching the lowest level.In general,LXM calcium-and silicon-based passivator had the best Cd reduction effect,with the optimal application amount of 6000 kg/hm^(2).
文摘Through pot tests of early rice and late rice in Cd polluted environment(soil Cd content,1.0 mg/kg),the inhibition and control effects of single application of organic fertilizers involving pig manure and biochar,and their combined application with alkaline amendments involving lime and oyster shell powder on soil Cd activation and rice Cd absorption were compared.And the correlation between soil available Cd and rice grain Cd was discussed.The results showed that compared with CK which did not involve amendments,the grain yields of early rice and late rice increased by 15.52%~36.01%and 12.02%~27.28%,respectively,the grain Cd content decreased by 24.76%~64.53%and 4.93%~58.32%,respectively,and the grain Cd accumulation decreased by 22.27%~51.76%and 33.84%~46.95%,respectively,except for single pig manure treatment.In particular,the Cd reduction effect of biochar was significantly better than that of pig manure,and the combined application with oyster shell powder was better than that with lime;after the harvest of early and late rice,the available Cd content in soil applied with amendments decreased by 35.00%~65.88%and 30.93%~68.57%,respectively,compared with CK.Further analysis showed that the soil available Cd content and rice grain Cd content could fit the linear equation well(R2>0.70,P<0.05),which demonstrated that the combined application of organic fertilizers and alkaline amendments can quickly reduce the Cd content of rice grain by passivating soil available Cd,and the combined application between biochar and oyster shell powder had a better effect.
文摘Groundwater over-exploitation is a major problem in groundwater development, utilization and protection. At present, the area of shallow groundwater over-exploitation in the High-tech Zone is 76 km^(2). In this study, the system and mechanism construction, engineering measure construction, and control effect of national comprehensive control project of groundwater over-exploitation areas in the High-tech Zone in 2020 were evaluated, and the comprehensive control of groundwater over-exploitation in the High-tech Zone in the year was summarized to provide effective basis for the continuous implementation of comprehensive control of groundwater over-exploitation. At the same time, the water-saving and exploitation reduction effect and generalizability of different measures were studied to provide useful reference for other over-exploitation areas.
基金Project supported by the National Natural Science Foundation of China(Grant No.61471039)
文摘Optoelectronic imaging equipment is easy to expose to active laser detection devices because of ＂cat eye＂ effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a cat eye target. Decentered field lens structure is adopted in the design without sacrificing imaging quality and clear aperture. An imaging system with±30° field of view is taken for example. The detailed design and simulation results are presented. The results indicate that this kind of optical system can reduce the retroreflection signal substantially and maintain acceptable imaging performance.
文摘With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Zeng Jie(曾杰)and Prof.Yang Jinlong(杨金龙),both from Hefei National Laboratory for Physical Sciences at the Microscale,University of Science and Technology of China,
文摘Greenhouse gas emissions are increas- ing every year and their effect on the environment is becoming increasingly serious. In 2009, the concen- tration of carbon dioxide in the earth＇s atmosphere reached 387 μL/L, the highest level in recorded histo- ry. This paper summarizes the global carbon emission situation, sources of greenhouse gases, and the con-tribution of agriculture to the accumutauon ot green- house gases. Several scientific measures are proposed to reduce greenhouse gas emissions resulting from ru- minant production such as improving animal perform- ance, regulating the rumen environment, and reduc- ing the amount of greenhouse gases emitted from live- stock manure.
基金Program of Key Laboratory of Zhuang and Yao Medicine(Gui Ke Ji Zi[2014]No.32)Program of Collaborative Innovation Center of Zhuang and Yao Medicine(Gui Jiao Ke Yan[2013]No.20)+2 种基金First-class Discipline in Guangxi:Traditional Chinese Medicine(0501802815)National Natural Science Foundation of China(82060695):Quality Evaluation of Dendrobium officinale Kimura et Migo in Guangxi Based on"Light-Quality"ResponseGuangxi Zhuang Autonomous Region National Medicine Resources and Application Engineering Research Center(Gui Fa Gai Gao Ji Han[2020]No.2605).
文摘The traditional Chinese medicine Aconm Lateralis Radix Praeparaia(Fuzi)is pungent and sweet in taste,hot in nature,and has high toxicity.It governs the meridians of the heart,kidney and spleen.It has the functions of restoring yang to save from collapse,dispersing cold and removing dampness,and warming the middle to relieve pain.It is often used for the treatment of yang collapse,cold limbs,weak pulse,heart yang deficiency,heart pain due to chest impediment,abdominal cold-pain,kidney yang deficiency,impotence and cold in womb,and syndrome of exogenous disease due to yang deficiency,etc.Its great yang qi and strong medicinal properties often bring about toxic and adverse effects.However,after processing or combination with other medicinal materials,the effects of Aconm Lateralis Radix Praeparaia are quite different.Not only the toxicity is greatly reduced,but also the curative effects are strengthened.Through searching related literature,this paper reviewed the researches about the toxicity reduction and curative effect improvement of Aconm Lateralis Radix Praeparaia,in order to provide a certain theoretic reference for future further research of Aconm Lateralis Radix Praeparaia.
文摘The oxygen reduction kinetics on polycobaltprotoporphyrin(PCoPP)film has been examined with the rotating disc electrode technique in O_2-saturated solution of various pH.PCoPP film promotes the oxygen reduction process via two electrons to produce peroxide over wide pH range. When pH value of solution decreases,catalytic activity of PCoPP film increases.Possible catalytic mechanisms have been proposed for oxygen reduction.
基金Project supported by the Natural Science Foundation of Hunan Province (Grant No. 09JJ6068)
文摘In order to develop technologies of friction drag reduction with a flexible tube to be used for water transport, experimental studies were carried out on the influence of Young’s modulus on the turbulent drag reduction. The friction coefficients of flexible tubes with different Young’s modulus were examined by using a sleeve-tube structure. The fluctuating vibration of the outer wall and the fluctuating pressure on the inner wall of the tubes were measured with a laser displacement sensor and a pressure sensor. The results are as follows. The smaller the Young’s modulus of a flexible tube and the larger the Reynolds number, the larger the turbulent drag reduction rates become. The transition from laminar flow to turbulent flow can be delayed with an appropriate Young’s modulus. Non-dimensional amplitude of fluctuating vibration on the outer wall is smaller than that of a viscous sub-layer thickness, and is positively correlated with the friction drag reduction.
