Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks th...Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks through to the wellbore. Autonomous inflow control device(AICD) is an important instrument maintain normal production after bottom water coning, however, the resistance increasing ability of the swirl type AICD is insufficient at present, which seriously affects the water control effect. Aiming this problem, this paper designs a multi-stage resistance-increasing and composite type AICD. The separation mechanism of oil-water two phases in this structure, the resistance form of oil-water single phase and the resistance-increasing principle of water phase are analyzed. Establishing the dual-phase multi-stage separation and resistance-increasing model, and verified by measuring the throttling pressure drop and oil-water volume fraction of the AICD, it is found that the composite type AICD has the effect of ICD and AICD at the same time, which can balance the production rate of each well section at the initial stage of production, delay the occurrence of bottom water coning. In the middle and later stages of production, water-blocking can be effectively increased to achieve water control and stable production.After structural sensitivity analysis, the influence law of various structural parameters on the water control performance of composite AICD was obtained. The simulation calculation results show that,compared with the existing swirl type AICD, composite AICD has higher sensitivity to moisture content,the water phase throttling pressure drop is increased by 4.5 times on average. The composite AICD is suitable for the entire stage of horizontal well production.展开更多
The coagulation process is one of the most important stages in water treatment plant, which involves many complex physical and chemical phenomena. Moreover, coagulant dosing rate is non-linearly correlated to raw wate...The coagulation process is one of the most important stages in water treatment plant, which involves many complex physical and chemical phenomena. Moreover, coagulant dosing rate is non-linearly correlated to raw water characteristics such as turbidity, conductivity, PH, temperature, etc. As such, coagulation reaction is hard or even impossible to control satisfactorily by conventional methods. Based on neural network and rule models, an expert system for determining the optimum chemical dosage rate is developed and used in a water treatment work, and the results of actual runs show that in the condition of satisfying the demand of drinking water quality, the usage of coagulant is lowered.展开更多
The reliability and robustness of the electro-hydraulic servo control system for heavy-duty forging machine play an important role in forging processes. A mathematic model of 50 MN water press for free forging was cre...The reliability and robustness of the electro-hydraulic servo control system for heavy-duty forging machine play an important role in forging processes. A mathematic model of 50 MN water press for free forging was created in this research. The dynamic robust compensator integrating with PID control method is designed and applied to the mathematical model simulation. The simulated results approved that the dynamic robust compensator application restrains interference from extra load and improves the electro-hydraulic position servo control system accuracy and stability.展开更多
Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with comp...Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with complex terrain and variable climate,as the research subject.Based on Google Earth Engine,we used Landsat data and the Open-surface Water Detection Method with Enhanced Impurity Control method to monitor the spatiotemporal dynamics of surface water area in Gansu Province from 1985 to 2022,and quantitatively analyzed the main causes of regional differences in surface water area.The findings revealed that surface water area in Gansu Province expanded by 406.88 km2 from 1985 to 2022.Seasonal surface water area exhibited significant fluctuations,while permanent surface water area showed a steady increase.Notably,terrestrial water storage exhibited a trend of first decreasing and then increasing,correlated with the dynamics of surface water area.Climate change and human activities jointly affected surface hydrological processes,with the impact of climate change being slightly higher than that of human activities.Spatially,climate change affected the'source'of surface water to a greater extent,while human activities tended to affect the'destination'of surface water.Challenges of surface water resources faced by inland arid and semi-arid areas like Gansu Province are multifaceted.Therefore,we summarized the surface hydrology patterns typical in inland arid and semi-arid areas and tailored surface water'supply-demand'balance strategies.The study not only sheds light on the dynamics of surface water area in Gansu Province,but also offers valuable insights for ecological protection and surface water resource management in inland arid and semi-arid areas facing water scarcity.展开更多
Although conventional model reference adaptive control （MRAC） achieves good tracking performance for cylinder control, the controller structure is much more complicated and has less robustness to disturbance in real...Although conventional model reference adaptive control （MRAC） achieves good tracking performance for cylinder control, the controller structure is much more complicated and has less robustness to disturbance in real applications. This paper discusses the use of simple adaptive control （SAC） for positioning a water hydraulic servo cylinder system. Compared with MRAC, SAC has a simpler and lower order structure, i.e., higher feasibility. The control performance of SAC is examined and evaluated on a water hydraulic servo cylinder system. With the recent increased concerns over global environmental problems, the water hydraulic technique using pure tap water as a pressure medium has become a new drive source comparable to electric, oil hydraulic, and pneumatic drive systems. This technique is also preferred because of its high power density, high safety against fire hazards in production plants, and easy availability. However, the main problems for precise control in a water hydraulic system are steady state errors and overshoot due to its large friction torque and considerable leakage flow. MRAC has been already applied to compensate for these effects, and better control performances have been obtained. However, there have been no reports on the application of SAC for water hydraulics. To make clear the merits of SAC, the tracking control performance and robustness are discussed based on experimental results. SAC is confirmed to give better tracking performance compared with PI control, and a control precision comparable to MRAC （within 10 μm of the reference position） and higher robustness to parameter change, despite the simple controller. The research results ensure a wider application of simple adaptive control in real mechanical systems.展开更多
This dissertation chiefly examines the functions of water hyacinth and discusses the potential problems associated with invasive species.In general,E.crassipes has significant potential as a source of biomass energy,s...This dissertation chiefly examines the functions of water hyacinth and discusses the potential problems associated with invasive species.In general,E.crassipes has significant potential as a source of biomass energy,such as improving physical properties of soil as well as soil structure;additionally,ventilates the soil and brings great conveniences for water penetrating through soil.With regard to the overall research,an amount of significant research has illustrated that water hyacinth can form dense mats that spread out across water surfaces in the end blocking the entire water body.Specifically,water hyacinth would change water clarity and lessening phytoplankton production,dissolved oxygen,nitrogen,phosphorous,heavy metals and concentrations of other pollutants.Relevant studies quoted in this report would gain prominence in further aquatic conservation and maintaining the integrity of ecosystem function since previous research and experience would be highlighted and explored in depth.Although some gaps between theory and experimental evidence still exist,preferable management method combines chemical,mechanical,fire and biological control methods with land management changes.展开更多
The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time de...The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.展开更多
Cultivating strong seedlings is an important guarantee for the production of high-quality flue-cured tobacco, while there are many disadvantages in tobacco floating system that is commonly adopted in China. To improve...Cultivating strong seedlings is an important guarantee for the production of high-quality flue-cured tobacco, while there are many disadvantages in tobacco floating system that is commonly adopted in China. To improve the tobacco floating system, with Xiangyan No.3 as experimental material, the effects of water control before transplanting and rooting powder treatment on tobacco seedling quality and physiological properties at green stage were investigated. The results showed that： （1） water control showed small influence on tobacco seedling quality, while rooting powder treatment and water control ＋ rooting powder treatment showed great influence on tobacco seedling quality, mainly represented by reduced plant height, thickened stem and increased dry matter accumulative amount; （2） water control before transplanting and rooting powder treatment all improved leaf chlorophyll content and root vigor of tobacco seedlings, and the effect of water control ＋ rooting powder treatment was best, followed by rooting powder treatment and water control; （3） all treatments increased the nitrate reductase and invertase activity, and reduced the MDA content of tobacco seedlings, and the effect of water control ＋ rooting powder treatment was best, followed by rooting powder treatment and water control. Mean- while, the treatment effect 10 d before the transplanting was better than that 5 d before the transplanting. In overall, the improvement effects of water control 10 d before transplanting ＋ rooting powder treatment on tobacco seedling quality and physiological properties at green stage were the best.展开更多
Caving of mine roofs from water inrush due to anomalous pressure is one of the major disasters and accidents that can occur in mines during production.Roof water inrush can trigger a wide range of roof collapse,causin...Caving of mine roofs from water inrush due to anomalous pressure is one of the major disasters and accidents that can occur in mines during production.Roof water inrush can trigger a wide range of roof collapse,causing major accidents from breaking roof supports while caving.These failures flood wells and do a great deal of damage to mines and endanger mine safety.Our objective is to analyze the anomalies of water inrush crushing the support at the #6301 working face in the Jisan Coal Mine of the Yanzhou Mining Group.Through information of water inrush to the roof,damage caused by tectonic movements,information on the damage caused by roof collapse and the theory about the distribution of pressure in mine abutments,we advice adjusting the length of the working face and the position of open-off cut relatively to the rich water area.In the case of anomalous roof pressure we should develop a state equation to estimate preventive measures with＂transferring rock beam＂theory.Simultaneously, we improve the capacity of drainage equipment and ensured adequate water retention at the storehouse. These are all major technologies to ensure the control and prevention against accidents caused by anomalous water inrush in roofs,thus ensuring safety in the production process of a coal mine.展开更多
The pollutants from the 15 rivers inflowing into Lake Taihu accounted for about 80% of the total amount of the pollutants inflowing into Lake Taihu. Therefore, overall treatment of the inflowing rivers of Taihu Lake i...The pollutants from the 15 rivers inflowing into Lake Taihu accounted for about 80% of the total amount of the pollutants inflowing into Lake Taihu. Therefore, overall treatment of the inflowing rivers of Taihu Lake is of great importance to the improvement of water environment in the valley and the eutrophication status in th lake. Firstly, the basic ideas, key taches and main methods for water pollution control of inflow rivers of Taihu Lake was put forward in this article, Basic on these theories, the pollutant source status in the comprehensive treatment zone of the 15 major inflow rivers was analysized, the countermeasures of pollution control and main regulation projects were introduced, and the total abatement of pollutants was predicted. With the implement of regulation projects, the number of rivers with water quality worse than Grade V among the 15 major inflow rivers had come from 9 to 3, and the eutrophication status of Taihu Lake had changed from medium level to light level. The overall treatment of the major inflow rivers of the Taihu Lake had achieved initial success.展开更多
A simple water iodizing system, which incorporates the Venturi principle in combination with the controlled release mechanism of a silicone-sodium iodide elastomer, for the iodization of rural piped-water supply in th...A simple water iodizing system, which incorporates the Venturi principle in combination with the controlled release mechanism of a silicone-sodium iodide elastomer, for the iodization of rural piped-water supply in the control of endemic iodine deficiency has been developed and its effectiveness evaluated in three Iban longhouse villages in the iodinedeficient district of Lubok Antu, Sarawak. Urines were collected for iodine assays from women aged 15-40 years before and at 6 and 12 months after the connection of the iodinating device; goiter assessment was performed on the women at the start and end of the 1-year study. Water samples were collected for iodine assays at 2-weekly intervals. In all three villages, significant and sustained increases in median urinary iodine excretions,reaching levels recommended for an iodine-suffcient population, were observed; goitre prevalences were reduced in all the villages (by 22.6% to 35.8%). The iodine levels in the water ranged from 34 μg/l to 212 μg/L. In the control village, median urinary iodine excretions remained essentially unchanged but a small increase in goiter prevalence was observed. The iodized water was well received by the villagers and no adverse effects of water iodization were observed. The system functioned unattended throughout the one year period. The cost of providing supplemental iodine via the iodizing device is approximately 60 cents (U.S.) per family per year which is affordable by either the Government or the villagers. It is concluded that the iodizing system offers a new cost-effective strategy for the control of endemic iodine deficiency in Sarawak and may have applications in other areas with similar water sources展开更多
In this paper, by in-depth geological research of Kalamkas Oilfield in Central Asia, the geological body has been re-ascertained; combined with fine study of reservoir engineering, based on the understanding of the di...In this paper, by in-depth geological research of Kalamkas Oilfield in Central Asia, the geological body has been re-ascertained; combined with fine study of reservoir engineering, based on the understanding of the distribution of remaining oil horizontal wells have been given full play to stabilizing oil production and controlling water cut, reducing the producing pressure drop, improving well productivity and other advantages, and the development and deployment has been optimized; horizontal wells have been applied to solve problems such as old well casing damages, shutting down wells, low-productivity and low- efficiency wells, and high water cut wells to improve the utilization rate of old wells; through separate layer system improved injection production pattern, adjustment wells have been optimized and deployed, and part measures wells have been preferably selected to tap the residual oil improve the degree of reserves control realize the stabilization of oil production and control of water cut in an old oilfield, and further improve the development effects.展开更多
Aiming at soft rock ground support issues under conditions of high stress and long-term water immersion, the ground failure mechanism is revealed by taking the deep-water sumps of Jiulong Mine as the engineering backg...Aiming at soft rock ground support issues under conditions of high stress and long-term water immersion, the ground failure mechanism is revealed by taking the deep-water sumps of Jiulong Mine as the engineering background and employing field investigation, tests of rock structure, mechanical properties and mineral composition. The main factors leading to the surrounding rock failure include the high and complex stress state of the water sumps, high-clay content and water-weakened rock, and the unreasonable support design. In this paper, the broken and fractured rock mass near roadway opening is considered as ground small-structure, and deep stable rock mass as ground large-structure. A support technology focusing on cutting off the water, strengthening the small structure of the rock and transferring the large structure of the rock is proposed. The proposed support technology of interconnecting the large and small structures, based on high-strength bolts, high-stiffness shotcrete layer plugging water,strengthening the small structure with deep-hole grouting and shallow-hole grouting, highpretensioned cables tensioned twice to make the large and small structures bearing the pressure evenly,channel-steel and high-pretensioned cables are used to control floor heave. The numerical simulation and field test show that this support system can control the rock deformation of the water sumps and provide technical support to similar roadway support designs.展开更多
Field experiments and laboratory analysis were carried out to determine the effects of controlled drainage（CTD） and conventional drainage（CVD） technologies on drainage volume, concentrations of NH4^＋ -N, NO3^-N, ...Field experiments and laboratory analysis were carried out to determine the effects of controlled drainage（CTD） and conventional drainage（CVD） technologies on drainage volume, concentrations of NH4^＋ -N, NO3^-N, and total phosphorus（TP）, nitrogen and phosphorus losses, rice yield,and water utilization efficiency. Results show that CTD technology can effectively reduce drainage times and volume; NH4^＋ -N, NO3^-N, and TP concentrations, from the first to the fourth day after four rainstorms decreased by 28.7%e46.7%, 37.5%e47.5%, and 22.7e31.2%, respectively,with CTD. These are significantly higher rates of decrease than those observed with CVD. CTD can significantly reduce nitrogen and phosphorus losses in field drainage, compared with CVD; the reduction rates observed in this study were, respectively, 66.72%, 55.56%, and 42.81% for NH4^＋ -N, NO3^-N, and TP. Furthermore, in the CTD mode, the rice yield was cut slightly. In the CVD mode, the water production efficiencies in unit irrigation water quantity, unit field water consumption, and unit evapotranspiration were, respectively, 0.85, 0.48, and 1.22 kg/m^3, while in the CTD mode they were 2.91, 0.84, and 1.61 kg/m^3 din other words, 3.42, 1.75, and 1.32 times those of CVD. Furthermore, the results of analysis of variance（ANOVA） show that the indicators in both the CVD and CTD modes, including the concentrations of NH4^＋ -N, NO3^-N, and TP, the losses of NH4^＋ -N, NO3^-N, and TP, irrigation water quantity, and water consumption, showed extremely significant differences between the modes, but the rice yield showed no significant difference.展开更多
Flood control detention basins （DBs） can act as water quality control structures or best management practices （BMPs）. A key pollutant that DBs serve to settle out is particulate phosphorus, which adsorbs onto sedi...Flood control detention basins （DBs） can act as water quality control structures or best management practices （BMPs）. A key pollutant that DBs serve to settle out is particulate phosphorus, which adsorbs onto sediment. This study examines the sediment phosphorus concentration and its relationship with the particle size of sediment microcosms from pre- and post-rain event samples obtained from six DBs located in Clark County, Nevada. DBs were allotted a land use classification to determine if there was a correlation between the sediment phosphorus concentration and surrounding land use. The curve number method was used to calculate the runoff and subsequent phosphorus carried into the DB by the runoff. Our data show sediment phosphorus concentrations to he highest in soils from undeveloped areas. Runoff amount also plays a substantial role in determining the amount of phosphorus brought into the DB by sediment. This research has implications for improvement of water quality in arid regions.展开更多
Water pollution control planning for the Taizi River watershed,a typical Chinese case study,is presented in this paper. Based on comprehensive analysis.water quality in the watershed was assessed and predicated;water ...Water pollution control planning for the Taizi River watershed,a typical Chinese case study,is presented in this paper. Based on comprehensive analysis.water quality in the watershed was assessed and predicated;water quality models for the river and reservoir were built;and function of water bodies and environmental assimilative capacity were determined ;and then the planning for industrial pollution sources and concentrated sewage treatment were made respectively.展开更多
Firstly,Jiang Shidu and his historical background were introduced.His water control practice and characteristics were analyzed in detail,such as drawing water to irrigate farmland,opening up waterways for grain transp...Firstly,Jiang Shidu and his historical background were introduced.His water control practice and characteristics were analyzed in detail,such as drawing water to irrigate farmland,opening up waterways for grain transportation by ship,guaranteeing the supply of fresh water to salt ponds,transforming drainage channels,establishing urban water supply system,and constructing military defense projects.展开更多
Based on the fundamental principles of total amount control of water use, the harmony theory was used in this study to develop a concept of the degree of harmony of total amount control of water use. Based on this con...Based on the fundamental principles of total amount control of water use, the harmony theory was used in this study to develop a concept of the degree of harmony of total amount control of water use. Based on this concept, the harmoniousness of total amount control of water use was analyzed in terms of the supply and demand of water resources, water resources management, water use benefits, and water-saving level. An evaluation index system of the degree of harmony of total amount control of water use was established, and a method for calculation of the degree of harmony of total amount control of water use was developed based on the analytic hierarchy process （AHP） and fuzzy comprehensive analysis （FCA） methods. The new evaluation index system was applied to a certain area in Jiangsu Province, China. The degree of harmony of total amount control of water use over this area was calculated for different years. Results indicate that the evaluation index system and calculation method proposed in this study are feasible, and such a harmoniousness analysis can provide scientific references for the strict water resources management system that will be implemented in China in the near future.展开更多
基金supported by National Natural Science Foundation(52204050)Sichuan Science and Technology Program(2021ZHCG0013,22ZDYF3009)。
文摘Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks through to the wellbore. Autonomous inflow control device(AICD) is an important instrument maintain normal production after bottom water coning, however, the resistance increasing ability of the swirl type AICD is insufficient at present, which seriously affects the water control effect. Aiming this problem, this paper designs a multi-stage resistance-increasing and composite type AICD. The separation mechanism of oil-water two phases in this structure, the resistance form of oil-water single phase and the resistance-increasing principle of water phase are analyzed. Establishing the dual-phase multi-stage separation and resistance-increasing model, and verified by measuring the throttling pressure drop and oil-water volume fraction of the AICD, it is found that the composite type AICD has the effect of ICD and AICD at the same time, which can balance the production rate of each well section at the initial stage of production, delay the occurrence of bottom water coning. In the middle and later stages of production, water-blocking can be effectively increased to achieve water control and stable production.After structural sensitivity analysis, the influence law of various structural parameters on the water control performance of composite AICD was obtained. The simulation calculation results show that,compared with the existing swirl type AICD, composite AICD has higher sensitivity to moisture content,the water phase throttling pressure drop is increased by 4.5 times on average. The composite AICD is suitable for the entire stage of horizontal well production.
基金This work was supported by the project 863 ofChina(No.863-511092)
文摘The coagulation process is one of the most important stages in water treatment plant, which involves many complex physical and chemical phenomena. Moreover, coagulant dosing rate is non-linearly correlated to raw water characteristics such as turbidity, conductivity, PH, temperature, etc. As such, coagulation reaction is hard or even impossible to control satisfactorily by conventional methods. Based on neural network and rule models, an expert system for determining the optimum chemical dosage rate is developed and used in a water treatment work, and the results of actual runs show that in the condition of satisfying the demand of drinking water quality, the usage of coagulant is lowered.
文摘The reliability and robustness of the electro-hydraulic servo control system for heavy-duty forging machine play an important role in forging processes. A mathematic model of 50 MN water press for free forging was created in this research. The dynamic robust compensator integrating with PID control method is designed and applied to the mathematical model simulation. The simulated results approved that the dynamic robust compensator application restrains interference from extra load and improves the electro-hydraulic position servo control system accuracy and stability.
基金This research was supported by the Third Xinjiang Scientific Expedition Program(2021xjkk010102)the National Natural Science Foundation of China(41261047,41761043)+1 种基金the Science and Technology Plan of Gansu Province,China(20YF3FA042)the Youth Teacher Scientific Capability Promoting Project of Northwest Normal University,Gansu Province,China(NWNU-LKQN-17-7).
文摘Understanding the dynamics of surface water area and their drivers is crucial for human survival and ecosystem stability in inland arid and semi-arid areas.This study took Gansu Province,China,a typical area with complex terrain and variable climate,as the research subject.Based on Google Earth Engine,we used Landsat data and the Open-surface Water Detection Method with Enhanced Impurity Control method to monitor the spatiotemporal dynamics of surface water area in Gansu Province from 1985 to 2022,and quantitatively analyzed the main causes of regional differences in surface water area.The findings revealed that surface water area in Gansu Province expanded by 406.88 km2 from 1985 to 2022.Seasonal surface water area exhibited significant fluctuations,while permanent surface water area showed a steady increase.Notably,terrestrial water storage exhibited a trend of first decreasing and then increasing,correlated with the dynamics of surface water area.Climate change and human activities jointly affected surface hydrological processes,with the impact of climate change being slightly higher than that of human activities.Spatially,climate change affected the'source'of surface water to a greater extent,while human activities tended to affect the'destination'of surface water.Challenges of surface water resources faced by inland arid and semi-arid areas like Gansu Province are multifaceted.Therefore,we summarized the surface hydrology patterns typical in inland arid and semi-arid areas and tailored surface water'supply-demand'balance strategies.The study not only sheds light on the dynamics of surface water area in Gansu Province,but also offers valuable insights for ecological protection and surface water resource management in inland arid and semi-arid areas facing water scarcity.
文摘Although conventional model reference adaptive control （MRAC） achieves good tracking performance for cylinder control, the controller structure is much more complicated and has less robustness to disturbance in real applications. This paper discusses the use of simple adaptive control （SAC） for positioning a water hydraulic servo cylinder system. Compared with MRAC, SAC has a simpler and lower order structure, i.e., higher feasibility. The control performance of SAC is examined and evaluated on a water hydraulic servo cylinder system. With the recent increased concerns over global environmental problems, the water hydraulic technique using pure tap water as a pressure medium has become a new drive source comparable to electric, oil hydraulic, and pneumatic drive systems. This technique is also preferred because of its high power density, high safety against fire hazards in production plants, and easy availability. However, the main problems for precise control in a water hydraulic system are steady state errors and overshoot due to its large friction torque and considerable leakage flow. MRAC has been already applied to compensate for these effects, and better control performances have been obtained. However, there have been no reports on the application of SAC for water hydraulics. To make clear the merits of SAC, the tracking control performance and robustness are discussed based on experimental results. SAC is confirmed to give better tracking performance compared with PI control, and a control precision comparable to MRAC （within 10 μm of the reference position） and higher robustness to parameter change, despite the simple controller. The research results ensure a wider application of simple adaptive control in real mechanical systems.
基金supported by National Natural Science Foundation of China(61233004,61221003,61374109,61104091,61304078,61473184)National Basic Research Program of China(973 Program)(2013CB035500)+2 种基金the International Cooperation Program of Shanghai Science and Technology Commission(12230709600)the Higher Education Research Fund for the Doctoral Program of China(20120073130006,20110073110018)the China Postdoctoral Science Foundation(2013M540364)
文摘This dissertation chiefly examines the functions of water hyacinth and discusses the potential problems associated with invasive species.In general,E.crassipes has significant potential as a source of biomass energy,such as improving physical properties of soil as well as soil structure;additionally,ventilates the soil and brings great conveniences for water penetrating through soil.With regard to the overall research,an amount of significant research has illustrated that water hyacinth can form dense mats that spread out across water surfaces in the end blocking the entire water body.Specifically,water hyacinth would change water clarity and lessening phytoplankton production,dissolved oxygen,nitrogen,phosphorous,heavy metals and concentrations of other pollutants.Relevant studies quoted in this report would gain prominence in further aquatic conservation and maintaining the integrity of ecosystem function since previous research and experience would be highlighted and explored in depth.Although some gaps between theory and experimental evidence still exist,preferable management method combines chemical,mechanical,fire and biological control methods with land management changes.
文摘The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.
基金Supported by Science and Technology Plan Project of Hunan Province(2013NK3036)Science and Technology Projects of Changsha Tobacco Company(12218,12231)~~
文摘Cultivating strong seedlings is an important guarantee for the production of high-quality flue-cured tobacco, while there are many disadvantages in tobacco floating system that is commonly adopted in China. To improve the tobacco floating system, with Xiangyan No.3 as experimental material, the effects of water control before transplanting and rooting powder treatment on tobacco seedling quality and physiological properties at green stage were investigated. The results showed that： （1） water control showed small influence on tobacco seedling quality, while rooting powder treatment and water control ＋ rooting powder treatment showed great influence on tobacco seedling quality, mainly represented by reduced plant height, thickened stem and increased dry matter accumulative amount; （2） water control before transplanting and rooting powder treatment all improved leaf chlorophyll content and root vigor of tobacco seedlings, and the effect of water control ＋ rooting powder treatment was best, followed by rooting powder treatment and water control; （3） all treatments increased the nitrate reductase and invertase activity, and reduced the MDA content of tobacco seedlings, and the effect of water control ＋ rooting powder treatment was best, followed by rooting powder treatment and water control. Mean- while, the treatment effect 10 d before the transplanting was better than that 5 d before the transplanting. In overall, the improvement effects of water control 10 d before transplanting ＋ rooting powder treatment on tobacco seedling quality and physiological properties at green stage were the best.
基金sponsored by the National Natural Science Foundation of China(No.50874021 )the Program for New Century Excellent Talents in University(No.NCET-08-0833)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0656) of the Ministry of Education of China.
文摘Caving of mine roofs from water inrush due to anomalous pressure is one of the major disasters and accidents that can occur in mines during production.Roof water inrush can trigger a wide range of roof collapse,causing major accidents from breaking roof supports while caving.These failures flood wells and do a great deal of damage to mines and endanger mine safety.Our objective is to analyze the anomalies of water inrush crushing the support at the #6301 working face in the Jisan Coal Mine of the Yanzhou Mining Group.Through information of water inrush to the roof,damage caused by tectonic movements,information on the damage caused by roof collapse and the theory about the distribution of pressure in mine abutments,we advice adjusting the length of the working face and the position of open-off cut relatively to the rich water area.In the case of anomalous roof pressure we should develop a state equation to estimate preventive measures with＂transferring rock beam＂theory.Simultaneously, we improve the capacity of drainage equipment and ensured adequate water retention at the storehouse. These are all major technologies to ensure the control and prevention against accidents caused by anomalous water inrush in roofs,thus ensuring safety in the production process of a coal mine.
文摘The pollutants from the 15 rivers inflowing into Lake Taihu accounted for about 80% of the total amount of the pollutants inflowing into Lake Taihu. Therefore, overall treatment of the inflowing rivers of Taihu Lake is of great importance to the improvement of water environment in the valley and the eutrophication status in th lake. Firstly, the basic ideas, key taches and main methods for water pollution control of inflow rivers of Taihu Lake was put forward in this article, Basic on these theories, the pollutant source status in the comprehensive treatment zone of the 15 major inflow rivers was analysized, the countermeasures of pollution control and main regulation projects were introduced, and the total abatement of pollutants was predicted. With the implement of regulation projects, the number of rivers with water quality worse than Grade V among the 15 major inflow rivers had come from 9 to 3, and the eutrophication status of Taihu Lake had changed from medium level to light level. The overall treatment of the major inflow rivers of the Taihu Lake had achieved initial success.
文摘A simple water iodizing system, which incorporates the Venturi principle in combination with the controlled release mechanism of a silicone-sodium iodide elastomer, for the iodization of rural piped-water supply in the control of endemic iodine deficiency has been developed and its effectiveness evaluated in three Iban longhouse villages in the iodinedeficient district of Lubok Antu, Sarawak. Urines were collected for iodine assays from women aged 15-40 years before and at 6 and 12 months after the connection of the iodinating device; goiter assessment was performed on the women at the start and end of the 1-year study. Water samples were collected for iodine assays at 2-weekly intervals. In all three villages, significant and sustained increases in median urinary iodine excretions,reaching levels recommended for an iodine-suffcient population, were observed; goitre prevalences were reduced in all the villages (by 22.6% to 35.8%). The iodine levels in the water ranged from 34 μg/l to 212 μg/L. In the control village, median urinary iodine excretions remained essentially unchanged but a small increase in goiter prevalence was observed. The iodized water was well received by the villagers and no adverse effects of water iodization were observed. The system functioned unattended throughout the one year period. The cost of providing supplemental iodine via the iodizing device is approximately 60 cents (U.S.) per family per year which is affordable by either the Government or the villagers. It is concluded that the iodizing system offers a new cost-effective strategy for the control of endemic iodine deficiency in Sarawak and may have applications in other areas with similar water sources
文摘In this paper, by in-depth geological research of Kalamkas Oilfield in Central Asia, the geological body has been re-ascertained; combined with fine study of reservoir engineering, based on the understanding of the distribution of remaining oil horizontal wells have been given full play to stabilizing oil production and controlling water cut, reducing the producing pressure drop, improving well productivity and other advantages, and the development and deployment has been optimized; horizontal wells have been applied to solve problems such as old well casing damages, shutting down wells, low-productivity and low- efficiency wells, and high water cut wells to improve the utilization rate of old wells; through separate layer system improved injection production pattern, adjustment wells have been optimized and deployed, and part measures wells have been preferably selected to tap the residual oil improve the degree of reserves control realize the stabilization of oil production and control of water cut in an old oilfield, and further improve the development effects.
基金sponsored by the National Natural Science Foundation of China(Nos.51134025 and 51274204)the New Century Excellent Talents in University(No.NCET-12-0965)
文摘Aiming at soft rock ground support issues under conditions of high stress and long-term water immersion, the ground failure mechanism is revealed by taking the deep-water sumps of Jiulong Mine as the engineering background and employing field investigation, tests of rock structure, mechanical properties and mineral composition. The main factors leading to the surrounding rock failure include the high and complex stress state of the water sumps, high-clay content and water-weakened rock, and the unreasonable support design. In this paper, the broken and fractured rock mass near roadway opening is considered as ground small-structure, and deep stable rock mass as ground large-structure. A support technology focusing on cutting off the water, strengthening the small structure of the rock and transferring the large structure of the rock is proposed. The proposed support technology of interconnecting the large and small structures, based on high-strength bolts, high-stiffness shotcrete layer plugging water,strengthening the small structure with deep-hole grouting and shallow-hole grouting, highpretensioned cables tensioned twice to make the large and small structures bearing the pressure evenly,channel-steel and high-pretensioned cables are used to control floor heave. The numerical simulation and field test show that this support system can control the rock deformation of the water sumps and provide technical support to similar roadway support designs.
基金supported by the National Natural Science Foundation of China(Grant No.51409124)the Natural Science Foundation of Jiangsu Province(Grant No.BK20140564)the Open Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2013490711)
文摘Field experiments and laboratory analysis were carried out to determine the effects of controlled drainage（CTD） and conventional drainage（CVD） technologies on drainage volume, concentrations of NH4^＋ -N, NO3^-N, and total phosphorus（TP）, nitrogen and phosphorus losses, rice yield,and water utilization efficiency. Results show that CTD technology can effectively reduce drainage times and volume; NH4^＋ -N, NO3^-N, and TP concentrations, from the first to the fourth day after four rainstorms decreased by 28.7%e46.7%, 37.5%e47.5%, and 22.7e31.2%, respectively,with CTD. These are significantly higher rates of decrease than those observed with CVD. CTD can significantly reduce nitrogen and phosphorus losses in field drainage, compared with CVD; the reduction rates observed in this study were, respectively, 66.72%, 55.56%, and 42.81% for NH4^＋ -N, NO3^-N, and TP. Furthermore, in the CTD mode, the rice yield was cut slightly. In the CVD mode, the water production efficiencies in unit irrigation water quantity, unit field water consumption, and unit evapotranspiration were, respectively, 0.85, 0.48, and 1.22 kg/m^3, while in the CTD mode they were 2.91, 0.84, and 1.61 kg/m^3 din other words, 3.42, 1.75, and 1.32 times those of CVD. Furthermore, the results of analysis of variance（ANOVA） show that the indicators in both the CVD and CTD modes, including the concentrations of NH4^＋ -N, NO3^-N, and TP, the losses of NH4^＋ -N, NO3^-N, and TP, irrigation water quantity, and water consumption, showed extremely significant differences between the modes, but the rice yield showed no significant difference.
基金supported by the Urban Flood Demonstration Program of the United States Army Corps of Engineers(Grant No.W912HZ-08-2-0021)
文摘Flood control detention basins （DBs） can act as water quality control structures or best management practices （BMPs）. A key pollutant that DBs serve to settle out is particulate phosphorus, which adsorbs onto sediment. This study examines the sediment phosphorus concentration and its relationship with the particle size of sediment microcosms from pre- and post-rain event samples obtained from six DBs located in Clark County, Nevada. DBs were allotted a land use classification to determine if there was a correlation between the sediment phosphorus concentration and surrounding land use. The curve number method was used to calculate the runoff and subsequent phosphorus carried into the DB by the runoff. Our data show sediment phosphorus concentrations to he highest in soils from undeveloped areas. Runoff amount also plays a substantial role in determining the amount of phosphorus brought into the DB by sediment. This research has implications for improvement of water quality in arid regions.
文摘Water pollution control planning for the Taizi River watershed,a typical Chinese case study,is presented in this paper. Based on comprehensive analysis.water quality in the watershed was assessed and predicated;water quality models for the river and reservoir were built;and function of water bodies and environmental assimilative capacity were determined ;and then the planning for industrial pollution sources and concentrated sewage treatment were made respectively.
文摘Firstly,Jiang Shidu and his historical background were introduced.His water control practice and characteristics were analyzed in detail,such as drawing water to irrigate farmland,opening up waterways for grain transportation by ship,guaranteeing the supply of fresh water to salt ponds,transforming drainage channels,establishing urban water supply system,and constructing military defense projects.
文摘Based on the fundamental principles of total amount control of water use, the harmony theory was used in this study to develop a concept of the degree of harmony of total amount control of water use. Based on this concept, the harmoniousness of total amount control of water use was analyzed in terms of the supply and demand of water resources, water resources management, water use benefits, and water-saving level. An evaluation index system of the degree of harmony of total amount control of water use was established, and a method for calculation of the degree of harmony of total amount control of water use was developed based on the analytic hierarchy process （AHP） and fuzzy comprehensive analysis （FCA） methods. The new evaluation index system was applied to a certain area in Jiangsu Province, China. The degree of harmony of total amount control of water use over this area was calculated for different years. Results indicate that the evaluation index system and calculation method proposed in this study are feasible, and such a harmoniousness analysis can provide scientific references for the strict water resources management system that will be implemented in China in the near future.
