The usage characteristics of the large numerals in child language reflects both linguistic and cognitive development.The present study systematically examined Mandarin children’s naturalistic use of large numerals“...The usage characteristics of the large numerals in child language reflects both linguistic and cognitive development.The present study systematically examined Mandarin children’s naturalistic use of large numerals“bai”,“qian”,and“wan”and compared it with adult usage patterns based on a self-constructed corpus.The results revealed a significant preference for the use of“bai”over both“qian”and“wan”among children and adults alike.This shared pattern suggests that children’s acquisition of large numerals is strongly shaped by adult language input.This study addresses a critical gap in research on the acquisition of large numerals by Mandarin-speaking children,providing valuable insights for the broader theoretical framework of cross-linguistic numerical cognition.展开更多
The problematic use of social media has numerous negative impacts on individuals'daily lives,interpersonal relationships,physical and mental health,and more.Currently,there are few methods and tools to alleviate p...The problematic use of social media has numerous negative impacts on individuals'daily lives,interpersonal relationships,physical and mental health,and more.Currently,there are few methods and tools to alleviate problematic social media,and their potential is yet to be fully realized.Emerging large language models(LLMs)are becoming increasingly popular for providing information and assistance to people and are being applied in many aspects of life.In mitigating problematic social media use,LLMs such as ChatGPT can play a positive role by serving as conversational partners and outlets for users,providing personalized information and resources,monitoring and intervening in problematic social media use,and more.In this process,we should recognize both the enormous potential and endless possibilities of LLMs such as ChatGPT,leveraging their advantages to better address problematic social media use,while also acknowledging the limitations and potential pitfalls of ChatGPT technology,such as errors,limitations in issue resolution,privacy and security concerns,and potential overreliance.When we leverage the advantages of LLMs to address issues in social media usage,we must adopt a cautious and ethical approach,being vigilant of the potential adverse effects that LLMs may have in addressing problematic social media use to better harness technology to serve individuals and society.展开更多
The tube hydro forming process for manufacturing the tubular part with large perimeter difference was studied by means of experiments and FE simulation. It is an asymmetrical one and the expansion ratio is 70 percent....The tube hydro forming process for manufacturing the tubular part with large perimeter difference was studied by means of experiments and FE simulation. It is an asymmetrical one and the expansion ratio is 70 percent. The part is successfully hydro formed by applying the useful wrinkles to accumulate sufficient metal in the area with large expansion ratio. The thickness distribution is analyzed, and the maximum thinning ratio of the part is 21.6 percent. It is shown from the experiment and simulation results that the tubular part with large perimeter difference, long expansion area and asymmetrical shape can be obtained in one step, applying the useful wrinkles. Typical failure modes were analyzed.展开更多
Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners( made of super alloy GH3030).The relative thickness( t0/ OD) of the tubular blank is approximately ...Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners( made of super alloy GH3030).The relative thickness( t0/ OD) of the tubular blank is approximately 0. 01,and the maximum expansion ratio( Dmax/ OD) of the needed part is more than 40%,and the length to diameter ratio of the expansion regionis more than 3. 0. It is very hard to manufacture this kind of ultra-thin-wall,curved axis and large expansion ratio tubular part without fracture and wrinkles. The success of the process is highly dependent on useful wrinkles with appropriate internal pressure and axial feeding. A simplified finite element model and a theoretical model are used for detecting the deformation behavior and forming laws. Further study results demonstrate that the useful wrinkles do not appear at the same time and middle-wrinkles need bigger axial force than tube-end-wrinkles and feeding-wrinkles. The wrinkles can transfer bigger axial force after its wave peak has come into contact with the die inner surface. The thickness thinning rate of the element at the peak is bigger than that at the trough. With the increase of the axial and hoop stress ratio,the critical buckling stress also increases. Microstructure examination results show that the grain size in the maximum thinning zone has been stretched and refined after the large deformation and annealing treatment.The process is feasible and the finished part is qualified.展开更多
The Neoarchaean to Palaeoproterozoic Transvaal Supergroup of the Kaapvaal Craton,southern Africa,is one of the best-preserved and most complete stratigraphic records across a critical in juncture in the Earth’s history.
From the point of spatio-temporal changes of ecological system type,function and value,in Menglian county,land using/cover data was based on three Landsat TM images(respectively obtained in2000,2005,2010 and 2015) whi...From the point of spatio-temporal changes of ecological system type,function and value,in Menglian county,land using/cover data was based on three Landsat TM images(respectively obtained in2000,2005,2010 and 2015) which were interpreted as basic information sources by using RS and GIS technology and then revising ecosystem service value per unit area in Menglian county.This paper has researched on the changes of ecosystem service value of economic garden for large area planting as well as evaluated ecosystem service value scientifically in Menglian county combined with the sensitivity analysis.The Results showed that:(1) In Menglian county,from 2000 to 2015,land use pattern manifested as the transformation from large areas of cultivated land,forest land and shrub to the economic landscape,the economic landscape is increased by 24458.31 hm^2,however,farm land,wood land and shrub are reduced by 24865.74 hm2 in total;(2) Changes of ecosystem service value is closely related to economic landscape development in Menglian county.The situation of ecosystem service value shows the changing trend from improvement to severity in 2000-2015.ESV is increased by 96.39 million yuan from 2000 to2005,whose annual growth rate is about 0.56%·a^(-1).But in the year of 2005 to 2015,ESV is reduced by120.23 million yuan and annual reduced rate is about 0.34%·a^(-1);(3) In Menglian county,the main ecological system is the woodland ecological system,the primary ecosystem service functions are biodiversity protection,gas regulation,soil formation and retention,climate regulation and water supply,the ecological benefit were decreased in 2000-2015;(4) From the aspect of space distribution,ecosystem service value in Menglian county is relatively high in the central area and relatively not high in the western and eastern area.ESV(yuan·hm`(-2)) was changed obvious,Gongxin town trended to decline,other towns increased first the then reduced.The temporal and spatial variation of ecosystem service value in Menglian county is affected by natural and human factors.The key to the development of economic landscape is rational land use according to the practical situation,which can create economic value and also keep its ecological value.展开更多
We propose a large parallax barrier by use of aperture grille. Main advantages of using aperture grille include no reflection and no absorption in apertures, as well as wide viewing angle. These advantages are investi...We propose a large parallax barrier by use of aperture grille. Main advantages of using aperture grille include no reflection and no absorption in apertures, as well as wide viewing angle. These advantages are investigated with theoretical calculations and experiments by use of several kinds of LED panels, such as a fine-pitch LED panel and a 140-inch large LED panel. Limitations of viewing angle by parallax barrier are analyzed in conventional black stripes on a transparent substrate type and in aperture grille type. Experimental results straw use of aperture grille increases contrast and reduce reflection on the aperture surface.展开更多
Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span cl...Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span closure girder and middle span closure girder.Each back span large unit is fabricated by welding several deck segments together in factory,and is erected by floating crane.As navigational clearance of the main bridge is high,the traditional truss lifting device can't satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight.Hence,a kind of lighter lifting device for the erection of back span large units was accepted for this bridge.In this paper,the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method.Because the bridge's navigation clearance is high,and the girder segment is wide and heavy,the meteorology and hydrology condition of the bridge district is abominable,and the requirements of long cable girder side pull-in,structure and performance propose high request to the lifting gantry.In this paper,the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.展开更多
Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularl...Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularly deep learning(DL),applied and relevant to computational mechanics(solid,fluids,finite-element technology)are reviewed in detail.Both hybrid and pure machine learning(ML)methods are discussed.Hybrid methods combine traditional PDE discretizations with ML methods either(1)to help model complex nonlinear constitutive relations,(2)to nonlinearly reduce the model order for efficient simulation(turbulence),or(3)to accelerate the simulation by predicting certain components in the traditional integration methods.Here,methods(1)and(2)relied on Long-Short-Term Memory(LSTM)architecture,with method(3)relying on convolutional neural networks.Pure ML methods to solve(nonlinear)PDEs are represented by Physics-Informed Neural network(PINN)methods,which could be combined with attention mechanism to address discontinuous solutions.Both LSTM and attention architectures,together with modern and generalized classic optimizers to include stochasticity for DL networks,are extensively reviewed.Kernel machines,including Gaussian processes,are provided to sufficient depth for more advanced works such as shallow networks with infinite width.Not only addressing experts,readers are assumed familiar with computational mechanics,but not with DL,whose concepts and applications are built up from the basics,aiming at bringing first-time learners quickly to the forefront of research.History and limitations of AI are recounted and discussed,with particular attention at pointing out misstatements or misconceptions of the classics,even in well-known references.Positioning and pointing control of a large-deformable beam is given as an example.展开更多
As more and more teachers and students in China are using Al tools,it has stirred wide public concern about how to maintain academic honesty and critical thinking。When homework piles high,and deadlines draw so nigh,w...As more and more teachers and students in China are using Al tools,it has stirred wide public concern about how to maintain academic honesty and critical thinking。When homework piles high,and deadlines draw so nigh,who do we turn to,quick and wise?DeepSeek Chat-our saving prize!Titled“DeepSeek to the Rescue”this is from a poem written by the large language model using the prompt"students using DeepSeek to do homework."Zhang Siling,an eighth grader at Beijing No.18 Middle School,has used DeepSeek to help write a composition for her Chinese class.She typed in the question,and in seconds DeepSeek generated a nicely written article.展开更多
In Japan, focal cities experience a number of probtems retated to deterioration of residentiat environment, quality of public service, and vitalization of commercial rand. SpecificaLLy, the presence of Large vacant to...In Japan, focal cities experience a number of probtems retated to deterioration of residentiat environment, quality of public service, and vitalization of commercial rand. SpecificaLLy, the presence of Large vacant tots behind sizable stores, office buildings, hospitals, and factories devitatize urban activity and its Landscape. Many local cities are seeking to actuatize a sustainable compact city with an integrated poputation, commerce, traffic and other pubLic services in ways that promote a tow carbon and energy-conserving society. Against the backdrop of these issues, this study examines the occurrence of large vacant lots and their utilization by tocat governments in Japan based on a questionnaire and fietd survey. It highlights severat cases in which a Large vacant tot is used to forward the development of a compact city by a tocat government.展开更多
We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectro...We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.展开更多
Recently, triboelectric nanogenerators （TENGs）, as a collection technology with characteristics of high reliability, high energy density and low cost, has attracted more and more attention. However, the energy comin...Recently, triboelectric nanogenerators （TENGs）, as a collection technology with characteristics of high reliability, high energy density and low cost, has attracted more and more attention. However, the energy coming from TENGs needs to be stored in a storage unit effectively due to its unstable ac output. The traditional energy storage circuit has an extremely low energy storage efficiency for TENGs because of their high internal impedance. This paper presents a new power management circuit used to optimize the energy using efficiency of TENGs, and realize large load capacity. The power management circuit mainly includes rectification storage circuit and DC-DC management circuit. A rotating TENG with maximal energy output of 106 mW at 170 rpm based on PCB is used for the experimental verification. Experimental results show that the power energy transforming to the storage capacitor reach up to 53 mW and the energy using efficiency is calculated as 50%. When different loading resistances range from 0.82 to 34.5 k^2 are connected to the storage capacitor in parallel, the power energy stored in the storage capacitor is all about 52.5 mW. Getting through the circuit, the power energy coming from the TENGs can be used to drive numerous conventional electronics, such as wearable watches.展开更多
Background The application of index of biotic integrity(IBI)to evaluate river health can be an essential method for river ecosystem management.However,these types of methods were developed in small,low-order streams,a...Background The application of index of biotic integrity(IBI)to evaluate river health can be an essential method for river ecosystem management.However,these types of methods were developed in small,low-order streams,and are therefore,infrequently applied to large rivers.To that end,phytoplankton communities and environmental variables were monitored in 30 sampling segments of the middle and lower reaches of the Yangtze River,China during the wet(July-August)and dry(November-December)seasons in 2017-2018.We developed a phytoplankton-based index of biotic integrity(P-IBI)and used the index to assess the ecological health of the Yangtze River.Relationships among P-IBI,its component metrics,and environmental factors were analyzed across different seasons.Results Results obtained from the P-IBI indicated that the phytoplankton-based ecological health of the Yangtze River was rated as“good”during both seasons,with an overall better condition in the dry season.During the wet season,there were scattered river segments with P-IBI ratings of“fair”or below.Water quality and land use appeared to shape the patterns of P-IBI.In the wet season,P-IBI negatively correlated with total phosphorus,nitrate,total suspended solids,turbidity,conductivity,and dissolved oxygen.In the dry season,P-IBI positively correlated with total nitrogen,ammonium,and nitrite,and negatively correlated with water temperature.Conclusions The ecological health of the Yangtze River as reflected by the P-IBI exhibited spatial and temporal variability,with the effect of water quality being greater than that of local land use.This study indicated the importance of considering seasonal effects in detecting large river ecological health.These findings enhanced our understanding of the ecological health and characterized potential benchmarks for management of the Yangtze River.These findings also may be applicable to other large rivers elsewhere.展开更多
文摘The usage characteristics of the large numerals in child language reflects both linguistic and cognitive development.The present study systematically examined Mandarin children’s naturalistic use of large numerals“bai”,“qian”,and“wan”and compared it with adult usage patterns based on a self-constructed corpus.The results revealed a significant preference for the use of“bai”over both“qian”and“wan”among children and adults alike.This shared pattern suggests that children’s acquisition of large numerals is strongly shaped by adult language input.This study addresses a critical gap in research on the acquisition of large numerals by Mandarin-speaking children,providing valuable insights for the broader theoretical framework of cross-linguistic numerical cognition.
文摘The problematic use of social media has numerous negative impacts on individuals'daily lives,interpersonal relationships,physical and mental health,and more.Currently,there are few methods and tools to alleviate problematic social media,and their potential is yet to be fully realized.Emerging large language models(LLMs)are becoming increasingly popular for providing information and assistance to people and are being applied in many aspects of life.In mitigating problematic social media use,LLMs such as ChatGPT can play a positive role by serving as conversational partners and outlets for users,providing personalized information and resources,monitoring and intervening in problematic social media use,and more.In this process,we should recognize both the enormous potential and endless possibilities of LLMs such as ChatGPT,leveraging their advantages to better address problematic social media use,while also acknowledging the limitations and potential pitfalls of ChatGPT technology,such as errors,limitations in issue resolution,privacy and security concerns,and potential overreliance.When we leverage the advantages of LLMs to address issues in social media usage,we must adopt a cautious and ethical approach,being vigilant of the potential adverse effects that LLMs may have in addressing problematic social media use to better harness technology to serve individuals and society.
文摘The tube hydro forming process for manufacturing the tubular part with large perimeter difference was studied by means of experiments and FE simulation. It is an asymmetrical one and the expansion ratio is 70 percent. The part is successfully hydro formed by applying the useful wrinkles to accumulate sufficient metal in the area with large expansion ratio. The thickness distribution is analyzed, and the maximum thinning ratio of the part is 21.6 percent. It is shown from the experiment and simulation results that the tubular part with large perimeter difference, long expansion area and asymmetrical shape can be obtained in one step, applying the useful wrinkles. Typical failure modes were analyzed.
基金Sponsored by the Major State BasicResearch Development Program(Grant No.613152)the International Cooperation of RFBR-NSFC(Grant No.51111120088)
文摘Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners( made of super alloy GH3030).The relative thickness( t0/ OD) of the tubular blank is approximately 0. 01,and the maximum expansion ratio( Dmax/ OD) of the needed part is more than 40%,and the length to diameter ratio of the expansion regionis more than 3. 0. It is very hard to manufacture this kind of ultra-thin-wall,curved axis and large expansion ratio tubular part without fracture and wrinkles. The success of the process is highly dependent on useful wrinkles with appropriate internal pressure and axial feeding. A simplified finite element model and a theoretical model are used for detecting the deformation behavior and forming laws. Further study results demonstrate that the useful wrinkles do not appear at the same time and middle-wrinkles need bigger axial force than tube-end-wrinkles and feeding-wrinkles. The wrinkles can transfer bigger axial force after its wave peak has come into contact with the die inner surface. The thickness thinning rate of the element at the peak is bigger than that at the trough. With the increase of the axial and hoop stress ratio,the critical buckling stress also increases. Microstructure examination results show that the grain size in the maximum thinning zone has been stretched and refined after the large deformation and annealing treatment.The process is feasible and the finished part is qualified.
文摘The Neoarchaean to Palaeoproterozoic Transvaal Supergroup of the Kaapvaal Craton,southern Africa,is one of the best-preserved and most complete stratigraphic records across a critical in juncture in the Earth’s history.
基金supported by the National Natural Science Foundation of China(Grant Nos.41361020,40961031)
文摘From the point of spatio-temporal changes of ecological system type,function and value,in Menglian county,land using/cover data was based on three Landsat TM images(respectively obtained in2000,2005,2010 and 2015) which were interpreted as basic information sources by using RS and GIS technology and then revising ecosystem service value per unit area in Menglian county.This paper has researched on the changes of ecosystem service value of economic garden for large area planting as well as evaluated ecosystem service value scientifically in Menglian county combined with the sensitivity analysis.The Results showed that:(1) In Menglian county,from 2000 to 2015,land use pattern manifested as the transformation from large areas of cultivated land,forest land and shrub to the economic landscape,the economic landscape is increased by 24458.31 hm^2,however,farm land,wood land and shrub are reduced by 24865.74 hm2 in total;(2) Changes of ecosystem service value is closely related to economic landscape development in Menglian county.The situation of ecosystem service value shows the changing trend from improvement to severity in 2000-2015.ESV is increased by 96.39 million yuan from 2000 to2005,whose annual growth rate is about 0.56%·a^(-1).But in the year of 2005 to 2015,ESV is reduced by120.23 million yuan and annual reduced rate is about 0.34%·a^(-1);(3) In Menglian county,the main ecological system is the woodland ecological system,the primary ecosystem service functions are biodiversity protection,gas regulation,soil formation and retention,climate regulation and water supply,the ecological benefit were decreased in 2000-2015;(4) From the aspect of space distribution,ecosystem service value in Menglian county is relatively high in the central area and relatively not high in the western and eastern area.ESV(yuan·hm`(-2)) was changed obvious,Gongxin town trended to decline,other towns increased first the then reduced.The temporal and spatial variation of ecosystem service value in Menglian county is affected by natural and human factors.The key to the development of economic landscape is rational land use according to the practical situation,which can create economic value and also keep its ecological value.
文摘We propose a large parallax barrier by use of aperture grille. Main advantages of using aperture grille include no reflection and no absorption in apertures, as well as wide viewing angle. These advantages are investigated with theoretical calculations and experiments by use of several kinds of LED panels, such as a fine-pitch LED panel and a 140-inch large LED panel. Limitations of viewing angle by parallax barrier are analyzed in conventional black stripes on a transparent substrate type and in aperture grille type. Experimental results straw use of aperture grille increases contrast and reduce reflection on the aperture surface.
基金National Science and Technology Support Program of China(No.2006BAG04B0)
文摘Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span closure girder and middle span closure girder.Each back span large unit is fabricated by welding several deck segments together in factory,and is erected by floating crane.As navigational clearance of the main bridge is high,the traditional truss lifting device can't satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight.Hence,a kind of lighter lifting device for the erection of back span large units was accepted for this bridge.In this paper,the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method.Because the bridge's navigation clearance is high,and the girder segment is wide and heavy,the meteorology and hydrology condition of the bridge district is abominable,and the requirements of long cable girder side pull-in,structure and performance propose high request to the lifting gantry.In this paper,the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.
文摘Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularly deep learning(DL),applied and relevant to computational mechanics(solid,fluids,finite-element technology)are reviewed in detail.Both hybrid and pure machine learning(ML)methods are discussed.Hybrid methods combine traditional PDE discretizations with ML methods either(1)to help model complex nonlinear constitutive relations,(2)to nonlinearly reduce the model order for efficient simulation(turbulence),or(3)to accelerate the simulation by predicting certain components in the traditional integration methods.Here,methods(1)and(2)relied on Long-Short-Term Memory(LSTM)architecture,with method(3)relying on convolutional neural networks.Pure ML methods to solve(nonlinear)PDEs are represented by Physics-Informed Neural network(PINN)methods,which could be combined with attention mechanism to address discontinuous solutions.Both LSTM and attention architectures,together with modern and generalized classic optimizers to include stochasticity for DL networks,are extensively reviewed.Kernel machines,including Gaussian processes,are provided to sufficient depth for more advanced works such as shallow networks with infinite width.Not only addressing experts,readers are assumed familiar with computational mechanics,but not with DL,whose concepts and applications are built up from the basics,aiming at bringing first-time learners quickly to the forefront of research.History and limitations of AI are recounted and discussed,with particular attention at pointing out misstatements or misconceptions of the classics,even in well-known references.Positioning and pointing control of a large-deformable beam is given as an example.
文摘As more and more teachers and students in China are using Al tools,it has stirred wide public concern about how to maintain academic honesty and critical thinking。When homework piles high,and deadlines draw so nigh,who do we turn to,quick and wise?DeepSeek Chat-our saving prize!Titled“DeepSeek to the Rescue”this is from a poem written by the large language model using the prompt"students using DeepSeek to do homework."Zhang Siling,an eighth grader at Beijing No.18 Middle School,has used DeepSeek to help write a composition for her Chinese class.She typed in the question,and in seconds DeepSeek generated a nicely written article.
文摘In Japan, focal cities experience a number of probtems retated to deterioration of residentiat environment, quality of public service, and vitalization of commercial rand. SpecificaLLy, the presence of Large vacant tots behind sizable stores, office buildings, hospitals, and factories devitatize urban activity and its Landscape. Many local cities are seeking to actuatize a sustainable compact city with an integrated poputation, commerce, traffic and other pubLic services in ways that promote a tow carbon and energy-conserving society. Against the backdrop of these issues, this study examines the occurrence of large vacant lots and their utilization by tocat governments in Japan based on a questionnaire and fietd survey. It highlights severat cases in which a Large vacant tot is used to forward the development of a compact city by a tocat government.
文摘We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.
文摘Recently, triboelectric nanogenerators （TENGs）, as a collection technology with characteristics of high reliability, high energy density and low cost, has attracted more and more attention. However, the energy coming from TENGs needs to be stored in a storage unit effectively due to its unstable ac output. The traditional energy storage circuit has an extremely low energy storage efficiency for TENGs because of their high internal impedance. This paper presents a new power management circuit used to optimize the energy using efficiency of TENGs, and realize large load capacity. The power management circuit mainly includes rectification storage circuit and DC-DC management circuit. A rotating TENG with maximal energy output of 106 mW at 170 rpm based on PCB is used for the experimental verification. Experimental results show that the power energy transforming to the storage capacitor reach up to 53 mW and the energy using efficiency is calculated as 50%. When different loading resistances range from 0.82 to 34.5 k^2 are connected to the storage capacitor in parallel, the power energy stored in the storage capacitor is all about 52.5 mW. Getting through the circuit, the power energy coming from the TENGs can be used to drive numerous conventional electronics, such as wearable watches.
基金supported by National Key R&D Program of China(2019YFD0901203)Chinese Academy of Sciences(ZDRW-ZS-2017-3-2).
文摘Background The application of index of biotic integrity(IBI)to evaluate river health can be an essential method for river ecosystem management.However,these types of methods were developed in small,low-order streams,and are therefore,infrequently applied to large rivers.To that end,phytoplankton communities and environmental variables were monitored in 30 sampling segments of the middle and lower reaches of the Yangtze River,China during the wet(July-August)and dry(November-December)seasons in 2017-2018.We developed a phytoplankton-based index of biotic integrity(P-IBI)and used the index to assess the ecological health of the Yangtze River.Relationships among P-IBI,its component metrics,and environmental factors were analyzed across different seasons.Results Results obtained from the P-IBI indicated that the phytoplankton-based ecological health of the Yangtze River was rated as“good”during both seasons,with an overall better condition in the dry season.During the wet season,there were scattered river segments with P-IBI ratings of“fair”or below.Water quality and land use appeared to shape the patterns of P-IBI.In the wet season,P-IBI negatively correlated with total phosphorus,nitrate,total suspended solids,turbidity,conductivity,and dissolved oxygen.In the dry season,P-IBI positively correlated with total nitrogen,ammonium,and nitrite,and negatively correlated with water temperature.Conclusions The ecological health of the Yangtze River as reflected by the P-IBI exhibited spatial and temporal variability,with the effect of water quality being greater than that of local land use.This study indicated the importance of considering seasonal effects in detecting large river ecological health.These findings enhanced our understanding of the ecological health and characterized potential benchmarks for management of the Yangtze River.These findings also may be applicable to other large rivers elsewhere.
