In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain (NCP). The combined effects of water and nitrogen application uniformity on the gr...In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain (NCP). The combined effects of water and nitrogen application uniformity on the grain yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) have become a research hotspot. In this study, a two-year field experiment was conducted during the winter wheat growing season in 2016–2018 to evaluate the water application uniformity of a center pivot with two low pressure sprinklers (the R3000 sprinklers were installed in the first span, the corresponding treatment was RS;the D3000 sprinklers were installed in the second span, the corresponding treatment was DS) and a P85A impact sprinkler as the end gun (the corresponding treatment was EG), and to analyze its effects on grain yield, WUE and NUE. The results showed that the water application uniformity coefficients of R3000, D3000 and P85A along the radial direction of the pivot (CUH) were 87.5, 79.5 and 65%, respectively. While the uniformity coefficients along the traveling direction of the pivot (CUC) were all higher than 85%. The effects of water application uniformity of the R3000 and D3000 sprinklers on grain yield were not significant (P>0.05);however, the average grain yield of EG was significantly lower (P<0.05) than those of RS and DS, by 9.4 and 11.1% during two growing seasons, respectively. The coefficients of variation (CV) of the grain yield had a negative correlation with the uniformity coefficient. The CV of WUE was more strongly affected by the water application uniformity, compared with the WUE value, among the three treatments. The NUE of RS was higher than those of DS and EG by about 6.1 and 4.8%, respectively, but there were no significant differences in NUE among the three treatments during the two growing seasons. Although the CUH of the D3000 sprinklers was lower than that of the R3000, it had only limited effects on the grain yield, WUE and NUE. However, the cost of D3000 sprinklers is lower than that of R3000 sprinklers. Therefore, the D3000 sprinklers are recommended for winter wheat irrigation and fertigation in the NCP.展开更多
Laboratory and field experiments were conducted to investigate the effects of water application intensity（WAI） on soil salinity management and the growth of Festuca arundinacea（festuca） under three stages of water...Laboratory and field experiments were conducted to investigate the effects of water application intensity（WAI） on soil salinity management and the growth of Festuca arundinacea（festuca） under three stages of water and salt management strategies using microsprinkler irrigation in Hebei Province, North China. The soil water content（è） and salinity of homogeneous coastal saline soils were evaluated under different water application intensities in the laboratory experiment. The results indicated that the WAI of microsprinkler irrigation influenced the è, electrical conductivity（ECe） and p H of saline soils. As the WAI increased, the average values of è and ECe in the 0–40 cm profile also increased, while their average values in the 40–60 cm profile decreased. The p H value also slightly decreased as depth increased, but no significant differences were observed between the different treatments. The time periods of the water redistribution treatments had no obvious effects. Based on the results for è, ECe and p H, a smaller WAI was more desirable. The field experiment was conducted after being considered the results of the technical parameter experiment and evaporation, wind and leaching duration. The field experiment included three stages of water and salt regulation, based on three soil matric potentials（SMP）, in which the SMP at a 20-cm depth below the surface was used to trigger irrigation. The results showed that the microsprinkler irrigation created an appropriate environment for festuca growth through the three stages of water and salt regulation. The low-salinity conditions that occurred at 0–10 cm depth during the first stage（-5 k Pa） continued to expand through the next two stages. The average p H value was less than 8.5. The tiller number of festuca increased as SMP decreased from the first stage to the third stage. After the three stages of water and salt regulation, the highly saline soil gradually changed to a low-saline soil. Overall, based on the salt desalinization, the microsprinkler irrigation and three stages of water and salt regulation could be successfully used to cultivate plants for the reclamation of coastal saline land in North China.展开更多
To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to e...To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents.To achieve this objective,a laboratory experiment was conducted with three soil salinity treatments(2.26,10.13,and 22.29 dS/m)and three water application intensity treatments(3.05,5.19,and 7.23 mm/h).The results showed that the effect of soil salinity on soil water content,electrical conductivity,and pH was significant,and the effect of the water application intensity was insignificant.High soil water content was present in the 40e60 cm profile in all soil salinity treatments,and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment.Significant salt leaching occurred in all treatments,and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment.In the medium and high soil salinity treatments,pH exhibited a decreasing trend,with no trend change in the low soil salinity treatment,and the pH value was higher in the medium water application intensity treatment than in the other two treatments.These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts(EC)in the upper 20 cm of the soil profile,and it would be better to maintain a lower value of the water application intensity.展开更多
Dry season water application and conservation were studied for two years in Ado Ekiti to evaluate their effects on the performance of plantain Musa spp.. The treatments were： morning watering （MW）, evening watering...Dry season water application and conservation were studied for two years in Ado Ekiti to evaluate their effects on the performance of plantain Musa spp.. The treatments were： morning watering （MW）, evening watering （EW）, morning and evening watering （MEW）, morning watering ＋ mulch （MW ＋ ML）, evening watering ＋ mulch （EW ＋ ML）, morning and evening watering ＋ mulch （MEW ＋ ML）, mulch （ML） and Control. Height and girth increase, number of green leaves, yield and yield parameters were the highest in the MEW ＋ ML which were identical to those of Evening watering ＋ mulch and morning ＋ evening watering. The evening or morning watering with mulch was identical but showed better performance than those without mulch. The mulched plants and the control showed the least performance. It is therefore recommended that proper water conservation in plantain plantation will improve banana survival during dry season and subsequently increase yield in the study area.展开更多
Flexible underwater vehicles with high maneuverability,high efficiency,high speed,and low disturbance have shown great application potential and research significance in underwater engineering,ocean exploration,scient...Flexible underwater vehicles with high maneuverability,high efficiency,high speed,and low disturbance have shown great application potential and research significance in underwater engineering,ocean exploration,scientific investigation and other fields.The research and development of flexible stimulus-responsive actuators is key to the development of high-performance underwater vehicles.At present,the main drive methods for underwater devices include electric drive,magnetic drive,light drive,thermal drive,and chemical drive.In this work,the research progress of stimuli-responsive actuators in water environment is reviewed from the stimuli-responsive patterns,functional design,fabrication methods,and applications in water environment.Firstly,the actuation principles and characteristics of electro-responsive,magnetic-responsive,photo-responsive,thermo-responsive actuators,and chemically responsive actuators are reviewed.Subsequently,several design requirements for the desired flexible actuators are introduced.After that,the common fabrication methods are summarized.The typical application of the stimuli-responsive actuator in the water environment is further discussed in combination with the multi-stimuli-responsive characteristics.Finally,the challenges faced by the application of stimuli-responsive actuators in the water environment are analyzed,and the corresponding viewpoints are presented.This review offers guidance for designing and preparing stimulus-responsive actuators and outlines directions for further development in fields such as ocean energy exploration and surface reconnaissance.展开更多
One important indicator of the good performance of rotating sprinklers is the uniformity of rotation.The objective of this experimental study was to investigate the rotation uniformity and water application rate of th...One important indicator of the good performance of rotating sprinklers is the uniformity of rotation.The objective of this experimental study was to investigate the rotation uniformity and water application rate of the newly designed complete fluidic sprinkler in comparison to the widely used impact sprinkler,with the goal to offer recommendations to improve the fluidic sprinkler’s operation performance.Single-sprinkler water application experiments were conducted in accordance with the American Society of Agricultural and Biological Engineers standard.Sprinkler completion time through the four quadrants of rotation and water delivery in catch cans were measured at different operating pressures for each sprinkler-nozzle size configuration.The capabilities of Matrix Laboratory were employed to simulate the overlap of adjacent quadrants and to visualize the effect of sprinkler rotation speed variation on water application rate.Quadrant completion time variations were small for both impact and fluidic sprinklers.However,variations in completion time through the quadrants were higher for the fluidic sprinkler compared to the impact sprinkler.Relatively higher variations in water application rates were also observed for the fluidic sprinkler.The optimization of the design features of the fluidic component is necessary to improve rotation stability and to minimize variability in water application rate of the fluidic sprinkler.The study significantly highlighted some performance qualities of the complete fluidic sprinkler in comparison to that of the impact sprinkler.The findings of this research will help to improve the efficiency of the new type complete fluidic sprinkler.展开更多
With increasing water shortage resources and extravagant nitrogen application, there is an urgent need to optimize irrigation regimes and nitrogen management for winter wheat（Triticum aestivum L.） in the North China...With increasing water shortage resources and extravagant nitrogen application, there is an urgent need to optimize irrigation regimes and nitrogen management for winter wheat（Triticum aestivum L.） in the North China Plain（NCP）. A 4-year field experiment was conducted to evaluate the effect of three irrigation levels（W1, irrigation once at jointing stage; W2, irrigation once at jointing and once at heading stage; W3, irrigation once at jointing, once at heading, and once at filling stage; 60 mm each irrigation） and four N fertilizer rates（N0, 0; N1, 100 kg N ha-（-1）; N2, 200 kg N ha-（-1）; N3, 300 kg N ha-（-1）） on wheat yield, water use efficiency, fertilizer agronomic efficiency, and economic benefits. The results showed that wheat yield under W2 condition was similar to that under W3, and greater than that under W1 at the same nitrogen level. Yield with the N1 treatment was higher than that with the N0 treatment, but not significantly different from that obtained with the N2 and N3 treatments. The W2 N1 treatment resulted in the highest water use and fertilizer agronomic efficiencies. Compared with local traditional practice（W3 N3）, the net income and output-input ratio of W2 N1 were greater by 12.3 and 19.5%, respectively. These findings suggest that two irrigation events of 60 mm each coupled with application of 100 kg N ha-（–1） is sufficient to provide a high wheat yield during drought growing seasons in the NCP.展开更多
Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a disti...Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a distinct seasonal variation of the alkalinity, which is concerned with the process of vertical mixing. Different specific alkalinity in various water masses has been found. On the basis of the difference of the specific alkalinity and the distribution of alkalinity, two water fronts in summer season, located at 27°-30°N and 124°-1 27°E, (Ⅰ), and at the northern waters about one latitude from the Taiwan Island, (Ⅱ); one in winter season at about one longitude from coast of mainland of China and 26°-30°N were found. In summer season, about 1-2 longitudes eastward shift of front (Ⅰ) is found by comparison of data in May and August. And the high alkalinity of the northern East China Sea in summer season may be caused by the Huanghe River runoff flowing southward along with the Huanghai Sea Coastal Current.展开更多
There are abundant water power resources in the Yalong River which are suitable for the large hydroelectric engineering. But a reliability study should be made for the valley which liable to frequent earthquakes. The ...There are abundant water power resources in the Yalong River which are suitable for the large hydroelectric engineering. But a reliability study should be made for the valley which liable to frequent earthquakes. The color infrared aerophotos, multi-spectral photography and thermal infrared scanning had been specially done besides MSS image, processing. Researches on remote sensing applications to engineering geology, hydrogeology, deformation of neo-tectonics, Iandslide, mud-rock flow, ecological environment and geographical information system had been carried out by more than 20 research units.展开更多
1. PREFACE Lingdingyang is a trumpet estuary. It accepts the runoff of the Dongjiang River, the Beijiang River, the Zhengjiang River and the Liusihe River. It also accepts a part of the runoff of the Xijiang River. It...1. PREFACE Lingdingyang is a trumpet estuary. It accepts the runoff of the Dongjiang River, the Beijiang River, the Zhengjiang River and the Liusihe River. It also accepts a part of the runoff of the Xijiang River. Its mean year runoff is 1.742×10" M^3. In resent ten years, industry and agriculture are developing rapidly in Guangzhou City, Dongguan City, Zhongshan City, Shunde County, Panyu County. Lingdingyang’s pollution is increesing. Water quality of lingdingyang is steadily deteriorated. In order to investigate the situation of water environment of Lingdingyang, we study its static environmental capacity of nitrogen and phosphorus. LANDSAT imageries are used in the study. The concentrations of nitrogen and phosphorous is detected by convention method.展开更多
Microbial flocculant （MBF） is a kind of novel flocculant, which is widely used for the food industry, highly concentrated organic waste water treatment and the urban water supply technology. Due to its characteristi...Microbial flocculant （MBF） is a kind of novel flocculant, which is widely used for the food industry, highly concentrated organic waste water treatment and the urban water supply technology. Due to its characteristics of superior flocculation effect, without secondary pollution to the environment and being easily degraded, MBF has been emerging as a hotspot of water treatment research in recent years. In this paper, the latest progress of the preparation of MBFs and the flocculating mechanism were presented. The practical application research of MBFs for water treatment was reviewed. Finally, suggestions and development prospect of research on MBFs were discussed.展开更多
This study was conducted to evaluate the water application uniformity for a drip irrigation system, considering the water quality and the duration of usage. The uniformity parameters, Emission Uniformity (EU %) and Un...This study was conducted to evaluate the water application uniformity for a drip irrigation system, considering the water quality and the duration of usage. The uniformity parameters, Emission Uniformity (EU %) and Uniformity Coefficient (UC %) were determined for the drip irrigation system </span><span style="font-family:Verdana;">installed over a year of performance. The procedures are based on taking</span><span style="font-family:Verdana;"> measurements of emitter discharge along selected driplines on a sub-main. The catch can </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">be</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> identified as L1A, L1B, L1C, L1D, same for L2A to L2D, L3A to L3D and L4A to L4D. This gave a total of sixteen (16) measurement positions as there were 4 driplines. Results indicated that the uniformity of water application was 90% indicating that the emitter was still good after a year of installation. The average discharge rate was 0.57</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">l/h. The uniformity coefficient (UC %) for the gravity-fed drip irrigation system was 78%, indicating good water application and was quite significant for the evaluation of the uniform distribution of water for the design. The expansion of this irrigation method in rural communities could contribute to relevant water savings in most areas of the Upper West Region of Ghana.展开更多
To address the issues of energy crisis and global warming, novel renewable carbon-free or carbon-neutral energy sources must be identified and developed. A deeper understanding of photosynthesis is the key to provide ...To address the issues of energy crisis and global warming, novel renewable carbon-free or carbon-neutral energy sources must be identified and developed. A deeper understanding of photosynthesis is the key to provide a solid foundation to facilitate this transformation. To mimic the water oxidation of photosystem II oxygen evolving complex, Mn-oxo complexes and Co-phosphate catalytic material were discovered in solar energy storage. Building on these discoveries, recent advances in solar energy conversion showed a compelling working principle by combing the active Mn-oxo and Co-based catalysts in water splitting with semiconductor heteronanostructures for effective solar energy harnessing. In this review the appealing systems including Mn-oxo tetramer/Nafion, Mn-oxo dimer/TiO2, Mn-oxo oligomer/WO3, Co-Pi/Fe2O3, and Co-Pi/ZnO are summarized and discussed. These accomplishments offer a promising framework and have a profound impact in the field of solar fuel production.展开更多
Plots under conservation tillage may require higher amount of potassium(K) application for augmenting productivity due to its stratification in upper soil layers, thereby reducing K supplying capacity in a medium or l...Plots under conservation tillage may require higher amount of potassium(K) application for augmenting productivity due to its stratification in upper soil layers, thereby reducing K supplying capacity in a medium or long-term period. To test this hypothesis, a field experiment was performed in 2002-2003 and 2006-2007 to study the effect of K and several crop rotations on yield, water productivity, carbon sequestration, grain quality, soil K status and economic benefits derived in maize(Zea mays L)/cowpea(Vigna sinensis L.) based cropping system under minimum tillage(MT). All crops recorded higher grain yield with a higher dose of K(120 kg K2 O ha-1) than recommended K(40 kg K2 O ha-1). The five years' average yield data showed that higher K application(120 kg K2 O ha-1) produced 16.4%(P<0.05)more maize equivalent yield. Cowpea based rotation yielded 14.2%(P<0.05) higher production than maize based rotation. The maximum enhancement was found in cowpea-mustard rotation. Relationship between yield and sustainable indices revealed that only agronomic efficiency of fertilizer input was significantly correlated with yield. Similarly, higherdoses of K application not only increased the water use efficiency(WUE) of all crops, but also reduced runoff and soil loss by 16.5% and 15.8% under maize and 23.3% and 19.7% under cowpea cover, respectively. This study also revealed that on an average 16.5% of left over carbon input contributed to soil organic carbon(SOC). Here, cowpea based rotation with the higher K application increased carbon sequestration in soil. Potassium fertilization also significantly improved the nutritional value of harvested grain by increasing the protein content for maize(by 9.5%) and cowpea(by 10.6%). The oil content in mustard increased by 5.0% and 6.0% after maize and cowpea, respectively. Net return also increased with the application of the higher K than recommended K and the trend was similar to yield. Hence, the present study demonstrated the potential yield and profit gains along with resource conservation in the Indian Himalayas due to annual additions of higher amount of K than the recommended dose. The impact of high K application was maximum in the cowpea-mustard rotation.展开更多
Engineered magnetic nanoparticles （MNPs） hold great potential in environmental, biomedical, and clin- ical applications owing to their many unique properties. This contribution provides an overview of iron oxide MNP...Engineered magnetic nanoparticles （MNPs） hold great potential in environmental, biomedical, and clin- ical applications owing to their many unique properties. This contribution provides an overview of iron oxide MNPs used in environmental, biomedical, and clinical fields. The first part discusses the use of MNPs for environmental purposes, such as contaminant removal, remediation, and water treatment, with a focus on the use of zero-valent iron, magnetite （Fe304）, and maghemite （~,-Fe203） nanoparticles, either alone or incorporated onto membrane materials. The second part of this review elaborates on the use of MNPs in the biomedical and clinical fields with particular attention to the application of superparamag- netic iron oxide nanoparticles （SP1ONs）, which have gained research focus recently owing to their many desirable features such as biocompatibility, biodegradability, ease of synthesis and absence of hysteresis. The properties of MNPs and their ability to work at both cellular and molecular levels have allowed their application in vitro and in vivo including drug delivery, hyperthermia treatment, radio-therapeutics, gene delivery, and biotherapeutics. Physiochemical properties such as size, shape, and surface and magnetic properties as well as agglomeration of MNPs and methods to enhance their stability are also discussed.展开更多
This study used a 1.5-layer reduced-gravity numerical model to investigate the nonlinear dynamics of Kuroshio intrusion into the Luzon Strait.The model results suggested that both basin-scale wind curl and lateral fri...This study used a 1.5-layer reduced-gravity numerical model to investigate the nonlinear dynamics of Kuroshio intrusion into the Luzon Strait.The model results suggested that both basin-scale wind curl and lateral friction are the primary factors that control the transformation of the flow,although inertia also plays an important role.Using an idealized model,both the mechanism via which the flow pattern changes depending on the two primary factors and the occurrence of hysteresis were investigated.It was established that the transformation of the Kuroshio flow field between the four previously reported flow patterns(i.e.,leaping across,current looping,eddy shedding,and branch intruding) can be explained under a unified theoretical framework.A diagram is proposed to explain how the flow field transforms between the four patterns from a certain prior state when varying the values of the controlling factors.展开更多
Overuse of fossil fuels led to energy crises and pollution.Thus,alternative energy sources are needed.Hydrogen,with its clean and high-density traits,is seen as a future energy carrier.Producing hydrogen from electric...Overuse of fossil fuels led to energy crises and pollution.Thus,alternative energy sources are needed.Hydrogen,with its clean and high-density traits,is seen as a future energy carrier.Producing hydrogen from electricity can store renewable energy for a sustainable hydrogen economy.While much research on water electrolysis hydrogen production systems exists,comprehensive reviews of engineering applications are scarce.This review sums up progress and improvement strategies of common water electrolysis technologies(alkaline water electrolysis,proton exchange membrane water electrolysis,solid oxide water electrolysis,and anion exchange membrane water electrolysis,etc.),including component and material research and development.It also reviews these technologies by development and maturity,especially their engineering applications,discussing features and prospects.Bottlenecks of different technologies are compared and analyzed,and future directions are summarized.The aim is to link academic material research with industrial manufacturing.展开更多
基金The research was supported by the National Key Research and Development Program of China(2017YFDO201502)the National Natural Science Foundation of China(51621061 and 51939005)+1 种基金the Science and Technology Open Cooperation Project of Henan Province,China(172106000015)the Open Fund of NationalEngineering Laboratory of Crop Stress Resistance Breeding,China(NELCOF20190104).
文摘In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain (NCP). The combined effects of water and nitrogen application uniformity on the grain yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) have become a research hotspot. In this study, a two-year field experiment was conducted during the winter wheat growing season in 2016–2018 to evaluate the water application uniformity of a center pivot with two low pressure sprinklers (the R3000 sprinklers were installed in the first span, the corresponding treatment was RS;the D3000 sprinklers were installed in the second span, the corresponding treatment was DS) and a P85A impact sprinkler as the end gun (the corresponding treatment was EG), and to analyze its effects on grain yield, WUE and NUE. The results showed that the water application uniformity coefficients of R3000, D3000 and P85A along the radial direction of the pivot (CUH) were 87.5, 79.5 and 65%, respectively. While the uniformity coefficients along the traveling direction of the pivot (CUC) were all higher than 85%. The effects of water application uniformity of the R3000 and D3000 sprinklers on grain yield were not significant (P>0.05);however, the average grain yield of EG was significantly lower (P<0.05) than those of RS and DS, by 9.4 and 11.1% during two growing seasons, respectively. The coefficients of variation (CV) of the grain yield had a negative correlation with the uniformity coefficient. The CV of WUE was more strongly affected by the water application uniformity, compared with the WUE value, among the three treatments. The NUE of RS was higher than those of DS and EG by about 6.1 and 4.8%, respectively, but there were no significant differences in NUE among the three treatments during the two growing seasons. Although the CUH of the D3000 sprinklers was lower than that of the R3000, it had only limited effects on the grain yield, WUE and NUE. However, the cost of D3000 sprinklers is lower than that of R3000 sprinklers. Therefore, the D3000 sprinklers are recommended for winter wheat irrigation and fertigation in the NCP.
基金supported by the National High-Technology R&D Program of China (2013 BAC02B02 and 2013BAC02B01)the National Science Foundation for Young Scientists of China (51409126)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (1033000001)the Action Plan for Development of Western China of Chinese Academy of Sciences (KZCX 2-XB3-16)
文摘Laboratory and field experiments were conducted to investigate the effects of water application intensity（WAI） on soil salinity management and the growth of Festuca arundinacea（festuca） under three stages of water and salt management strategies using microsprinkler irrigation in Hebei Province, North China. The soil water content（è） and salinity of homogeneous coastal saline soils were evaluated under different water application intensities in the laboratory experiment. The results indicated that the WAI of microsprinkler irrigation influenced the è, electrical conductivity（ECe） and p H of saline soils. As the WAI increased, the average values of è and ECe in the 0–40 cm profile also increased, while their average values in the 40–60 cm profile decreased. The p H value also slightly decreased as depth increased, but no significant differences were observed between the different treatments. The time periods of the water redistribution treatments had no obvious effects. Based on the results for è, ECe and p H, a smaller WAI was more desirable. The field experiment was conducted after being considered the results of the technical parameter experiment and evaporation, wind and leaching duration. The field experiment included three stages of water and salt regulation, based on three soil matric potentials（SMP）, in which the SMP at a 20-cm depth below the surface was used to trigger irrigation. The results showed that the microsprinkler irrigation created an appropriate environment for festuca growth through the three stages of water and salt regulation. The low-salinity conditions that occurred at 0–10 cm depth during the first stage（-5 k Pa） continued to expand through the next two stages. The average p H value was less than 8.5. The tiller number of festuca increased as SMP decreased from the first stage to the third stage. After the three stages of water and salt regulation, the highly saline soil gradually changed to a low-saline soil. Overall, based on the salt desalinization, the microsprinkler irrigation and three stages of water and salt regulation could be successfully used to cultivate plants for the reclamation of coastal saline land in North China.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2016B14614)the Program of China Scholarship Council(Grant No.201906715015)+1 种基金the National Key Research and Development Program of China(Grant No.2017YFC040320502)a project funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents.To achieve this objective,a laboratory experiment was conducted with three soil salinity treatments(2.26,10.13,and 22.29 dS/m)and three water application intensity treatments(3.05,5.19,and 7.23 mm/h).The results showed that the effect of soil salinity on soil water content,electrical conductivity,and pH was significant,and the effect of the water application intensity was insignificant.High soil water content was present in the 40e60 cm profile in all soil salinity treatments,and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment.Significant salt leaching occurred in all treatments,and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment.In the medium and high soil salinity treatments,pH exhibited a decreasing trend,with no trend change in the low soil salinity treatment,and the pH value was higher in the medium water application intensity treatment than in the other two treatments.These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts(EC)in the upper 20 cm of the soil profile,and it would be better to maintain a lower value of the water application intensity.
文摘Dry season water application and conservation were studied for two years in Ado Ekiti to evaluate their effects on the performance of plantain Musa spp.. The treatments were： morning watering （MW）, evening watering （EW）, morning and evening watering （MEW）, morning watering ＋ mulch （MW ＋ ML）, evening watering ＋ mulch （EW ＋ ML）, morning and evening watering ＋ mulch （MEW ＋ ML）, mulch （ML） and Control. Height and girth increase, number of green leaves, yield and yield parameters were the highest in the MEW ＋ ML which were identical to those of Evening watering ＋ mulch and morning ＋ evening watering. The evening or morning watering with mulch was identical but showed better performance than those without mulch. The mulched plants and the control showed the least performance. It is therefore recommended that proper water conservation in plantain plantation will improve banana survival during dry season and subsequently increase yield in the study area.
基金supported by the National Key Research and Development Program of China(2022YFB4703401)the Ministry of Education Joint Fund(8091B032250)the Fundamental Research Funds for the Central Universities(B240205045)。
文摘Flexible underwater vehicles with high maneuverability,high efficiency,high speed,and low disturbance have shown great application potential and research significance in underwater engineering,ocean exploration,scientific investigation and other fields.The research and development of flexible stimulus-responsive actuators is key to the development of high-performance underwater vehicles.At present,the main drive methods for underwater devices include electric drive,magnetic drive,light drive,thermal drive,and chemical drive.In this work,the research progress of stimuli-responsive actuators in water environment is reviewed from the stimuli-responsive patterns,functional design,fabrication methods,and applications in water environment.Firstly,the actuation principles and characteristics of electro-responsive,magnetic-responsive,photo-responsive,thermo-responsive actuators,and chemically responsive actuators are reviewed.Subsequently,several design requirements for the desired flexible actuators are introduced.After that,the common fabrication methods are summarized.The typical application of the stimuli-responsive actuator in the water environment is further discussed in combination with the multi-stimuli-responsive characteristics.Finally,the challenges faced by the application of stimuli-responsive actuators in the water environment are analyzed,and the corresponding viewpoints are presented.This review offers guidance for designing and preparing stimulus-responsive actuators and outlines directions for further development in fields such as ocean energy exploration and surface reconnaissance.
基金the financial support from the Program for National Hi-tech Research and Development(863 Program,No.2011AA100506 and No.2011GB2C100015)National Natural Science Foundation of China(No.51109098).
文摘One important indicator of the good performance of rotating sprinklers is the uniformity of rotation.The objective of this experimental study was to investigate the rotation uniformity and water application rate of the newly designed complete fluidic sprinkler in comparison to the widely used impact sprinkler,with the goal to offer recommendations to improve the fluidic sprinkler’s operation performance.Single-sprinkler water application experiments were conducted in accordance with the American Society of Agricultural and Biological Engineers standard.Sprinkler completion time through the four quadrants of rotation and water delivery in catch cans were measured at different operating pressures for each sprinkler-nozzle size configuration.The capabilities of Matrix Laboratory were employed to simulate the overlap of adjacent quadrants and to visualize the effect of sprinkler rotation speed variation on water application rate.Quadrant completion time variations were small for both impact and fluidic sprinklers.However,variations in completion time through the quadrants were higher for the fluidic sprinkler compared to the impact sprinkler.Relatively higher variations in water application rates were also observed for the fluidic sprinkler.The optimization of the design features of the fluidic component is necessary to improve rotation stability and to minimize variability in water application rate of the fluidic sprinkler.The study significantly highlighted some performance qualities of the complete fluidic sprinkler in comparison to that of the impact sprinkler.The findings of this research will help to improve the efficiency of the new type complete fluidic sprinkler.
基金supported by the National Key Research and Development Program of China (2016YFD0300808)the National Key Technologies R&D Program of China during the 12th Five-Year Plan period (2013BAD05B02)+2 种基金the National Natural Science Foundation of China (31571612 and 31100191)the Science and Technology Service Network Initiative of Chinese Academy of Sciences (KFJ-STSZDTP-001)the Hebei Key Research and Development Program, China (15226407D and 17227006D)
文摘With increasing water shortage resources and extravagant nitrogen application, there is an urgent need to optimize irrigation regimes and nitrogen management for winter wheat（Triticum aestivum L.） in the North China Plain（NCP）. A 4-year field experiment was conducted to evaluate the effect of three irrigation levels（W1, irrigation once at jointing stage; W2, irrigation once at jointing and once at heading stage; W3, irrigation once at jointing, once at heading, and once at filling stage; 60 mm each irrigation） and four N fertilizer rates（N0, 0; N1, 100 kg N ha-（-1）; N2, 200 kg N ha-（-1）; N3, 300 kg N ha-（-1）） on wheat yield, water use efficiency, fertilizer agronomic efficiency, and economic benefits. The results showed that wheat yield under W2 condition was similar to that under W3, and greater than that under W1 at the same nitrogen level. Yield with the N1 treatment was higher than that with the N0 treatment, but not significantly different from that obtained with the N2 and N3 treatments. The W2 N1 treatment resulted in the highest water use and fertilizer agronomic efficiencies. Compared with local traditional practice（W3 N3）, the net income and output-input ratio of W2 N1 were greater by 12.3 and 19.5%, respectively. These findings suggest that two irrigation events of 60 mm each coupled with application of 100 kg N ha-（–1） is sufficient to provide a high wheat yield during drought growing seasons in the NCP.
文摘Surface distribution and seasonal variation of alkalinity and specific alkalinity in Kuroshio area of the East ChinaSea and their application to the water mass tracing are discussed in this paper. Results show a distinct seasonal variation of the alkalinity, which is concerned with the process of vertical mixing. Different specific alkalinity in various water masses has been found. On the basis of the difference of the specific alkalinity and the distribution of alkalinity, two water fronts in summer season, located at 27°-30°N and 124°-1 27°E, (Ⅰ), and at the northern waters about one latitude from the Taiwan Island, (Ⅱ); one in winter season at about one longitude from coast of mainland of China and 26°-30°N were found. In summer season, about 1-2 longitudes eastward shift of front (Ⅰ) is found by comparison of data in May and August. And the high alkalinity of the northern East China Sea in summer season may be caused by the Huanghe River runoff flowing southward along with the Huanghai Sea Coastal Current.
文摘There are abundant water power resources in the Yalong River which are suitable for the large hydroelectric engineering. But a reliability study should be made for the valley which liable to frequent earthquakes. The color infrared aerophotos, multi-spectral photography and thermal infrared scanning had been specially done besides MSS image, processing. Researches on remote sensing applications to engineering geology, hydrogeology, deformation of neo-tectonics, Iandslide, mud-rock flow, ecological environment and geographical information system had been carried out by more than 20 research units.
文摘1. PREFACE Lingdingyang is a trumpet estuary. It accepts the runoff of the Dongjiang River, the Beijiang River, the Zhengjiang River and the Liusihe River. It also accepts a part of the runoff of the Xijiang River. Its mean year runoff is 1.742×10" M^3. In resent ten years, industry and agriculture are developing rapidly in Guangzhou City, Dongguan City, Zhongshan City, Shunde County, Panyu County. Lingdingyang’s pollution is increesing. Water quality of lingdingyang is steadily deteriorated. In order to investigate the situation of water environment of Lingdingyang, we study its static environmental capacity of nitrogen and phosphorus. LANDSAT imageries are used in the study. The concentrations of nitrogen and phosphorous is detected by convention method.
文摘Microbial flocculant （MBF） is a kind of novel flocculant, which is widely used for the food industry, highly concentrated organic waste water treatment and the urban water supply technology. Due to its characteristics of superior flocculation effect, without secondary pollution to the environment and being easily degraded, MBF has been emerging as a hotspot of water treatment research in recent years. In this paper, the latest progress of the preparation of MBFs and the flocculating mechanism were presented. The practical application research of MBFs for water treatment was reviewed. Finally, suggestions and development prospect of research on MBFs were discussed.
文摘This study was conducted to evaluate the water application uniformity for a drip irrigation system, considering the water quality and the duration of usage. The uniformity parameters, Emission Uniformity (EU %) and Uniformity Coefficient (UC %) were determined for the drip irrigation system </span><span style="font-family:Verdana;">installed over a year of performance. The procedures are based on taking</span><span style="font-family:Verdana;"> measurements of emitter discharge along selected driplines on a sub-main. The catch can </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">be</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> identified as L1A, L1B, L1C, L1D, same for L2A to L2D, L3A to L3D and L4A to L4D. This gave a total of sixteen (16) measurement positions as there were 4 driplines. Results indicated that the uniformity of water application was 90% indicating that the emitter was still good after a year of installation. The average discharge rate was 0.57</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">l/h. The uniformity coefficient (UC %) for the gravity-fed drip irrigation system was 78%, indicating good water application and was quite significant for the evaluation of the uniform distribution of water for the design. The expansion of this irrigation method in rural communities could contribute to relevant water savings in most areas of the Upper West Region of Ghana.
基金supported by the University of Massachusetts Dartmouth and in part by a grant from the USDA CSREES
文摘To address the issues of energy crisis and global warming, novel renewable carbon-free or carbon-neutral energy sources must be identified and developed. A deeper understanding of photosynthesis is the key to provide a solid foundation to facilitate this transformation. To mimic the water oxidation of photosystem II oxygen evolving complex, Mn-oxo complexes and Co-phosphate catalytic material were discovered in solar energy storage. Building on these discoveries, recent advances in solar energy conversion showed a compelling working principle by combing the active Mn-oxo and Co-based catalysts in water splitting with semiconductor heteronanostructures for effective solar energy harnessing. In this review the appealing systems including Mn-oxo tetramer/Nafion, Mn-oxo dimer/TiO2, Mn-oxo oligomer/WO3, Co-Pi/Fe2O3, and Co-Pi/ZnO are summarized and discussed. These accomplishments offer a promising framework and have a profound impact in the field of solar fuel production.
基金funded by the Indian Council of Agricultural Research(ICAR),New Delhi
文摘Plots under conservation tillage may require higher amount of potassium(K) application for augmenting productivity due to its stratification in upper soil layers, thereby reducing K supplying capacity in a medium or long-term period. To test this hypothesis, a field experiment was performed in 2002-2003 and 2006-2007 to study the effect of K and several crop rotations on yield, water productivity, carbon sequestration, grain quality, soil K status and economic benefits derived in maize(Zea mays L)/cowpea(Vigna sinensis L.) based cropping system under minimum tillage(MT). All crops recorded higher grain yield with a higher dose of K(120 kg K2 O ha-1) than recommended K(40 kg K2 O ha-1). The five years' average yield data showed that higher K application(120 kg K2 O ha-1) produced 16.4%(P<0.05)more maize equivalent yield. Cowpea based rotation yielded 14.2%(P<0.05) higher production than maize based rotation. The maximum enhancement was found in cowpea-mustard rotation. Relationship between yield and sustainable indices revealed that only agronomic efficiency of fertilizer input was significantly correlated with yield. Similarly, higherdoses of K application not only increased the water use efficiency(WUE) of all crops, but also reduced runoff and soil loss by 16.5% and 15.8% under maize and 23.3% and 19.7% under cowpea cover, respectively. This study also revealed that on an average 16.5% of left over carbon input contributed to soil organic carbon(SOC). Here, cowpea based rotation with the higher K application increased carbon sequestration in soil. Potassium fertilization also significantly improved the nutritional value of harvested grain by increasing the protein content for maize(by 9.5%) and cowpea(by 10.6%). The oil content in mustard increased by 5.0% and 6.0% after maize and cowpea, respectively. Net return also increased with the application of the higher K than recommended K and the trend was similar to yield. Hence, the present study demonstrated the potential yield and profit gains along with resource conservation in the Indian Himalayas due to annual additions of higher amount of K than the recommended dose. The impact of high K application was maximum in the cowpea-mustard rotation.
文摘Engineered magnetic nanoparticles （MNPs） hold great potential in environmental, biomedical, and clin- ical applications owing to their many unique properties. This contribution provides an overview of iron oxide MNPs used in environmental, biomedical, and clinical fields. The first part discusses the use of MNPs for environmental purposes, such as contaminant removal, remediation, and water treatment, with a focus on the use of zero-valent iron, magnetite （Fe304）, and maghemite （~,-Fe203） nanoparticles, either alone or incorporated onto membrane materials. The second part of this review elaborates on the use of MNPs in the biomedical and clinical fields with particular attention to the application of superparamag- netic iron oxide nanoparticles （SP1ONs）, which have gained research focus recently owing to their many desirable features such as biocompatibility, biodegradability, ease of synthesis and absence of hysteresis. The properties of MNPs and their ability to work at both cellular and molecular levels have allowed their application in vitro and in vivo including drug delivery, hyperthermia treatment, radio-therapeutics, gene delivery, and biotherapeutics. Physiochemical properties such as size, shape, and surface and magnetic properties as well as agglomeration of MNPs and methods to enhance their stability are also discussed.
基金supported by the National Programme on Global Change and Air-Sea Interaction(Grant No.GASI-IPOVAI-01-06)the National Natural Science Foundation of China(Grant Nos. 41630967,41476018,U1406401 & 41421005)the CAS Strategic Priority Project(Grant No.XDA11020101)
文摘This study used a 1.5-layer reduced-gravity numerical model to investigate the nonlinear dynamics of Kuroshio intrusion into the Luzon Strait.The model results suggested that both basin-scale wind curl and lateral friction are the primary factors that control the transformation of the flow,although inertia also plays an important role.Using an idealized model,both the mechanism via which the flow pattern changes depending on the two primary factors and the occurrence of hysteresis were investigated.It was established that the transformation of the Kuroshio flow field between the four previously reported flow patterns(i.e.,leaping across,current looping,eddy shedding,and branch intruding) can be explained under a unified theoretical framework.A diagram is proposed to explain how the flow field transforms between the four patterns from a certain prior state when varying the values of the controlling factors.
基金the National Natural Science Foundation of China(Grant No.22478423)for the support.
文摘Overuse of fossil fuels led to energy crises and pollution.Thus,alternative energy sources are needed.Hydrogen,with its clean and high-density traits,is seen as a future energy carrier.Producing hydrogen from electricity can store renewable energy for a sustainable hydrogen economy.While much research on water electrolysis hydrogen production systems exists,comprehensive reviews of engineering applications are scarce.This review sums up progress and improvement strategies of common water electrolysis technologies(alkaline water electrolysis,proton exchange membrane water electrolysis,solid oxide water electrolysis,and anion exchange membrane water electrolysis,etc.),including component and material research and development.It also reviews these technologies by development and maturity,especially their engineering applications,discussing features and prospects.Bottlenecks of different technologies are compared and analyzed,and future directions are summarized.The aim is to link academic material research with industrial manufacturing.
