In this paper, we consider the problem of the evaluation of system reliability using statistical data obtained from reliability tests of its elements, in which the lifetimes of elements are described using an exponent...In this paper, we consider the problem of the evaluation of system reliability using statistical data obtained from reliability tests of its elements, in which the lifetimes of elements are described using an exponential distribution. We assume that this lifetime data may be reported imprecisely and that this lack of precision may be described using fuzzy sets. As the direct application of the fuzzy sets methodology leads in this case to very complicated and time consuming calculations, we propose simple approximations of fuzzy numbers using shadowed sets introduced by Pedrycz (1998). The proposed methodology may be simply extended to the case of general lifetime probability distributions.展开更多
The effects of scatterers, fluctuation parameter and propagation clusters significantly affect the performance of κ-μ shadowed fading channel. On the other hand, opportunistic relaying is an efficient technique to i...The effects of scatterers, fluctuation parameter and propagation clusters significantly affect the performance of κ-μ shadowed fading channel. On the other hand, opportunistic relaying is an efficient technique to improve the performance of fading channels reducing the effects of aforementioned parameters. Motivated by these issues, in this paper, a secure wireless multicasting scenario through κ-μ shadowed fading channel is considered in the presence of multiple eavesdroppers with opportunistic relaying. The main purpose of this paper is to ensure the security level in wireless multicasting compensating the loss of security due to the effects of power ratio between dominant and scattered waves, fluctuation parameter, and the number of propagation clusters, multicast users and eavesdroppers, by opportunistic relaying technique. The closed-form analytical expressions are derived for the probability of non-zero secrecy multicast capacity (PNSMC) and the secure outage probability for multicasting (SOPM) to understand the insight of the effects of above parameters. The results show that the loss of security in multicasting through κ-μ shadowed fading channel can be significantly enhanced using opportunistic relaying technique by compensating the effects of scatterers, fluctuation parameter, and the number of propagation clusters, multicast users and eavesdroppers.展开更多
We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),a...We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.展开更多
Since ancient times,the Chinese New Year has been the most important festival for the Chinese nation,and"celebrating the Chinese New Year in museums"has gradually become a new trend in recent years.To enrich...Since ancient times,the Chinese New Year has been the most important festival for the Chinese nation,and"celebrating the Chinese New Year in museums"has gradually become a new trend in recent years.To enrich the cultural offerings during the holiday period and let the general audience experience the strong festive atmosphere in museums,on February 22 and 23,2024,on the eve of the Lantern Festival,the China Arts and Crafts Museum(China Intangible Cultural Heritage Museum)successfully held the"Encounter with Intangible Heritage""Capital Colors Shadow Play:Bejing Shadow Puppetry Outreach Activities."展开更多
China holds the distinction of hosting the most intangible cultural heritage items in the world,with 43 inscribed on the UNESCO Representative List of Intangible Cultural Heritage of Humanity,including Kunqu Opera,Chi...China holds the distinction of hosting the most intangible cultural heritage items in the world,with 43 inscribed on the UNESCO Representative List of Intangible Cultural Heritage of Humanity,including Kunqu Opera,Chinese Shadow Puppetry,and Taijiquan(Tai Chi).However,the knowledge and skills necessary to produce traditional crafts are often reliant on familial and apprenticeship inheritance.展开更多
LANGZHONG shadow play has been popular in 36 counties and cities in the vicinity of Langzhong in southwest China’s Sichuan Province,and is one of three major styles of Sichuan shadow play.Around 350 years ago,a puppe...LANGZHONG shadow play has been popular in 36 counties and cities in the vicinity of Langzhong in southwest China’s Sichuan Province,and is one of three major styles of Sichuan shadow play.Around 350 years ago,a puppeteer named Wang Yuansheng created the Langzhong shadow play by combining the unique characteristics of different styles of shadow play with north Sichuan’s folk customs.In 2008,the art of Sichuan shadow play which Langzhong shadow play is affiliated to was listed as a national intangible culture heritage item.展开更多
When designing a solar power plant, it is much more important to avoid the shadow on the PV Panels. As the shadow falls on the PV Panels;it significantly reduces the generation of required power as planned and designe...When designing a solar power plant, it is much more important to avoid the shadow on the PV Panels. As the shadow falls on the PV Panels;it significantly reduces the generation of required power as planned and designed. This research paper and case study will help a lot to avoid shadow, especially when selecting inter-row spacing between the strings of solar power plants.展开更多
The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Z...The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Zhai Pictorial terms of both content and form,and which was founded by the Haiist painter Wu Youru in 1890 in order to reward the increasing number of admirers,but it is still in the initial stage.Flying Shadow Pavilion Pictorial consisted of four parts:pictures of ladies in Shanghai costumes,news about current affairs,pictures of animals,and compilations of women,each of which was accompanied by the then popular notebooks,which were popular at the time among the then readers because of the matching of pictures with text and the mixing of narratives and discussions.This paper takes Flying Shadow Pavilion Pictorial as the main object,summarizes the existing literature about Flying Shadow Pavilion Pictorial,points out the deficiencies of the current research on this basis,and points out the development trend of Flying Shadow Pavilion Pictorial in the future research.展开更多
In this paper, we develop and analyze an energy efficient ARQ (automatic repeat request) initialized transmit diversity protocol for cooperative communications.Medium access control (MAC) layer packet retransmissi...In this paper, we develop and analyze an energy efficient ARQ (automatic repeat request) initialized transmit diversity protocol for cooperative communications.Medium access control (MAC) layer packet retransmission limit (similar to aShortRetryLimit or aLongRetryLimit [802.11-1997]) has been used as an actuator for transmit cooperative diversity initialization.We take the channel state information (CSI) as a function of retransmission tries and the number of retransmission tries is modeled as a random variable.Relays close to the source node are chosen for the transmit cooperation.Closed form expressions are obtained for symbol error rate (SER), outage capacity and outage probability for the proposed scheme in shadowed fading channels.This cooperative scheme achieves lower signal-to-noise ratio (SNR), stumpy outage probability, higher bandwidth, and transmit energy efficiencies for desired average symbol error rate (ASER) than the preceding ARQ based cooperative protocols.Finally, the results of computer simulations are included to demonstrate the efficacy of the proposed scheme and to verify the accuracy of the analytical expressions.展开更多
Accompanied by music,a turtle and a crane fight in a humorous story created by the simple interplay of light and curtain.This Chinese shadow puppetry performance makes the audience laugh.Backstage,Lu Baogang,a nationa...Accompanied by music,a turtle and a crane fight in a humorous story created by the simple interplay of light and curtain.This Chinese shadow puppetry performance makes the audience laugh.Backstage,Lu Baogang,a national-level inheritor of Beijing shadow puppetry art,and the other performers of the shadow puppetry troupe manipulate the silhouettes with great skill.展开更多
Automatic pavement crack detection is a critical task for maintaining the pavement stability and driving safety.The task is challenging because the shadows on the pavement may have similar intensity with the crack,whi...Automatic pavement crack detection is a critical task for maintaining the pavement stability and driving safety.The task is challenging because the shadows on the pavement may have similar intensity with the crack,which interfere with the crack detection performance.Till to the present,there still lacks efficient algorithm models and training datasets to deal with the interference brought by the shadows.To fill in the gap,we made several contributions as follows.First,we proposed a new pavement shadow and crack dataset,which contains a variety of shadow and pavement pixel size combinations.It also covers all common cracks(linear cracks and network cracks),placing higher demands on crack detection methods.Second,we designed a two-step shadow-removal-oriented crack detection approach:SROCD,which improves the performance of the algorithm by first removing the shadow and then detecting it.In addition to shadows,the method can cope with other noise disturbances.Third,we explored the mechanism of how shadows affect crack detection.Based on this mechanism,we propose a data augmentation method based on the difference in brightness values,which can adapt to brightness changes caused by seasonal and weather changes.Finally,we introduced a residual feature augmentation algorithm to detect small cracks that can predict sudden disasters,and the algorithm improves the performance of the model overall.We compare our method with the state-of-the-art methods on existing pavement crack datasets and the shadow-crack dataset,and the experimental results demonstrate the superiority of our method.展开更多
In this paper,we define a generalized Lipschitz shadowing property for flows and prove that a flowΦgenerated by a C1vector field X on a closed Riemannian manifold M has this generalized Lipschitz shadowing property i...In this paper,we define a generalized Lipschitz shadowing property for flows and prove that a flowΦgenerated by a C1vector field X on a closed Riemannian manifold M has this generalized Lipschitz shadowing property if and only if it is structurally stable.展开更多
In the Changqing Oilfield in northwest China, when traditional petroleum exploitation encounters forestry reserves or water source protection areas, sectorial well-factory design is proposed. The most distinct feature...In the Changqing Oilfield in northwest China, when traditional petroleum exploitation encounters forestry reserves or water source protection areas, sectorial well-factory design is proposed. The most distinct feature of a sectorial well-factory is the deviation of the well from the minimum horizontal principal stress, resulting in hydraulic fracture deflection after the initiation, along with possible well interference (i.e., fracture hit) and fracture coalescence in the oblique wells. Four indexes describing well deflection are then proposed according to fracture morphology. Several fracturing designs, including stage arrangement, fracturing sequences, and fracturing techniques are applied to study the feasibility of the sectorial well-factory design. The results show that the “gradual” or “sparse” stage arrangement, large injection rate, and simultaneous multifracture treatment can help to optimize the fracture morphology and stimulation design. However, the subsequent stress shadowing effect usually adversely affects the fracturing of adjacent wells. With a small initial horizontal stress difference, large injection rate and staggered stage arrangement can achieve ideal stimulation performance. Our results can provide a guidance for optimizing stimulation design in unconventional well-factory while taking into account environmental protection.展开更多
Although airborne hyperspectral data with detailed spatial and spectral information has demonstrated significant potential for tree species classification,it has not been widely used over large areas.A comprehensive p...Although airborne hyperspectral data with detailed spatial and spectral information has demonstrated significant potential for tree species classification,it has not been widely used over large areas.A comprehensive process based on multi-flightline airborne hyperspectral data is lacking over large,forested areas influenced by both the effects of bidirectional reflectance distribution function(BRDF)and cloud shadow contamination.In this study,hyperspectral data were collected over the Mengjiagang Forest Farm in Northeast China in the summer of 2017 using the Chinese Academy of Forestry's LiDAR,CCD,and hyperspectral systems(CAF-LiCHy).After BRDF correction and cloud shadow detection processing,a tree species classification workflow was developed for sunlit and cloud-shaded forest areas with input features of minimum noise fraction reduced bands,spectral vegetation indices,and texture information.Results indicate that BRDF-corrected sunlit hyperspectral data can provide a stable and high classification accuracy based on representative training data.Cloud-shaded pixels also have good spectral separability for species classification.The red-edge spectral information and ratio-based spectral indices with high importance scores are recommended as input features for species classification under varying light conditions.According to the classification accuracies through field survey data at multiple spatial scales,it was found that species classification within an extensive forest area using airborne hyperspectral data under various illuminations can be successfully carried out using the effective radiometric consistency process and feature selection strategy.展开更多
Based on the artificial intelligence algorithm of RetinaNet,we propose the Ghost-RetinaNet in this paper,a fast shadow detection method for photovoltaic panels,to solve the problems of extreme target density,large ove...Based on the artificial intelligence algorithm of RetinaNet,we propose the Ghost-RetinaNet in this paper,a fast shadow detection method for photovoltaic panels,to solve the problems of extreme target density,large overlap,high cost and poor real-time performance in photovoltaic panel shadow detection.Firstly,the Ghost CSP module based on Cross Stage Partial(CSP)is adopted in feature extraction network to improve the accuracy and detection speed.Based on extracted features,recursive feature fusion structure ismentioned to enhance the feature information of all objects.We introduce the SiLU activation function and CIoU Loss to increase the learning and generalization ability of the network and improve the positioning accuracy of the bounding box regression,respectively.Finally,in order to achieve fast detection,the Ghost strategy is chosen to lighten the size of the algorithm.The results of the experiment show that the average detection accuracy(mAP)of the algorithm can reach up to 97.17%,the model size is only 8.75 MB and the detection speed is highly up to 50.8 Frame per second(FPS),which can meet the requirements of real-time detection speed and accuracy of photovoltaic panels in the practical environment.The realization of the algorithm also provides new research methods and ideas for fault detection in the photovoltaic power generation system.展开更多
Target signal acquisition and detection based on sonar images is a challenging task due to the complex underwater environment.In order to solve the problem that some semantic information in sonar images is lost and mo...Target signal acquisition and detection based on sonar images is a challenging task due to the complex underwater environment.In order to solve the problem that some semantic information in sonar images is lost and model detection performance is degraded due to the complex imaging environment,we proposed a more effective and robust target detection framework based on deep learning,which can make full use of the acoustic shadow information in the forward-looking sonar images to assist underwater target detection.Firstly,the weighted box fusion method is adopted to generate a fusion box by weighted fusion of prediction boxes with high confidence,so as to obtain accurate acoustic shadow boxes.Further,the acoustic shadow box is cut down to get the feature map containing the acoustic shadow information,and then the acoustic shadow feature map and the target information feature map are adaptively fused to make full use of the acoustic shadow feature information.In addition,we introduce a threshold processing module to improve the attention of the model to important feature information.Through the underwater sonar dataset provided by Pengcheng Laboratory,the proposed method improved the average accuracy by 3.14%at the IoU threshold of 0.7,which is better than the current traditional target detection model.展开更多
We creatively employ the shadow radius to study the thermodynamics of a charged Ad S black hole with a nonlinear electrodynamics(NLED)term.First,the connection between the shadow radius and event horizon is constructe...We creatively employ the shadow radius to study the thermodynamics of a charged Ad S black hole with a nonlinear electrodynamics(NLED)term.First,the connection between the shadow radius and event horizon is constructed with the aid of the geodesic analysis.It turns out that the black hole shadow radius shows a positive correlation as a function of the event horizon radius.Then in the shadow context,we find that the black hole temperature and heat capacity can be presented by the shadow radius.Further analysis shows that the shadow radius can work similarly to the event horizon in revealing black hole phase transition process.In this sense,we construct the thermal profile of the charged Ad S black hole with inclusion of the NLED effect.In the P<Pc case,it is found that the N-type trend of the temperature given by the shadow radius is always consistent with that obtained by using the event horizon.Thus,we can conclude for the charged Ad S black hole that the phase transition process can be intuitively presented as the thermal profile in the shadow context.Finally,the effects of NLED are carefully analyzed.展开更多
Nowadays,security plays an important role in Internet of Things(IoT)environment especially in medical services’domains like disease prediction and medical data storage.In healthcare sector,huge volumes of data are ge...Nowadays,security plays an important role in Internet of Things(IoT)environment especially in medical services’domains like disease prediction and medical data storage.In healthcare sector,huge volumes of data are generated on a daily basis,owing to the involvement of advanced health care devices.In general terms,health care images are highly sensitive to alterations due to which any modifications in its content can result in faulty diagnosis.At the same time,it is also significant to maintain the delicate contents of health care images during reconstruction stage.Therefore,an encryption system is required in order to raise the privacy and security of healthcare data by not leaking any sensitive data.The current study introduces Improved Multileader Optimization with Shadow Image Encryption for Medical Image Security(IMLOSIE-MIS)technique for IoT environment.The aim of the proposed IMLOSIE-MIS model is to accomplish security by generating shadows and encrypting them effectively.To do so,the presented IMLOSIE-MIS model initially generates a set of shadows for every input medical image.Besides,shadow image encryption process takes place with the help of Multileader Optimization(MLO)withHomomorphic Encryption(IMLO-HE)technique,where the optimal keys are generated with the help of MLO algorithm.On the receiver side,decryption process is initially carried out and shadow image reconstruction process is conducted.The experimentation analysis was carried out on medical images and the results inferred that the proposed IMLOSIE-MIS model is an excellent performer compared to other models.The comparison study outcomes demonstrate that IMLOSIE-MIS model is robust and offers high security in IoT-enabled healthcare environment.展开更多
To overcome the problems of natural decreases in power quality,and to eliminate wind speed fluctuation due to wind shear and tower shadow effect arising from wind turbine structural parameters,an improved prediction m...To overcome the problems of natural decreases in power quality,and to eliminate wind speed fluctuation due to wind shear and tower shadow effect arising from wind turbine structural parameters,an improved prediction model accounting for the dual effect of wind shear and tower shadow is,in this paper,built.Compared to the conventional prediction model,the proposed model contains a new constraint condition,which makes the disturbance term caused by the tower shadow effect always negative so that the prediction result is closer to the actual situation.Furthermore,wind turbine structural parameters such as hub height,rotor diameter,the diameter of the tower top,and rotor overhang on wind shear and tower shadow effect are also explored in detail.The results show that the wind shear effect became weaker with the increase in hub height.The hub height is independent of the tower shadow effect.The rotor diameter is positively correlated with the wind shear and tower shadow effect.The tower shadow effect is positively correlated with the diameter of the tower top and negatively correlated with the rotor overhang.展开更多
文摘In this paper, we consider the problem of the evaluation of system reliability using statistical data obtained from reliability tests of its elements, in which the lifetimes of elements are described using an exponential distribution. We assume that this lifetime data may be reported imprecisely and that this lack of precision may be described using fuzzy sets. As the direct application of the fuzzy sets methodology leads in this case to very complicated and time consuming calculations, we propose simple approximations of fuzzy numbers using shadowed sets introduced by Pedrycz (1998). The proposed methodology may be simply extended to the case of general lifetime probability distributions.
文摘The effects of scatterers, fluctuation parameter and propagation clusters significantly affect the performance of κ-μ shadowed fading channel. On the other hand, opportunistic relaying is an efficient technique to improve the performance of fading channels reducing the effects of aforementioned parameters. Motivated by these issues, in this paper, a secure wireless multicasting scenario through κ-μ shadowed fading channel is considered in the presence of multiple eavesdroppers with opportunistic relaying. The main purpose of this paper is to ensure the security level in wireless multicasting compensating the loss of security due to the effects of power ratio between dominant and scattered waves, fluctuation parameter, and the number of propagation clusters, multicast users and eavesdroppers, by opportunistic relaying technique. The closed-form analytical expressions are derived for the probability of non-zero secrecy multicast capacity (PNSMC) and the secure outage probability for multicasting (SOPM) to understand the insight of the effects of above parameters. The results show that the loss of security in multicasting through κ-μ shadowed fading channel can be significantly enhanced using opportunistic relaying technique by compensating the effects of scatterers, fluctuation parameter, and the number of propagation clusters, multicast users and eavesdroppers.
基金Project supported by the National Natural Science Foundation of China (Grant No.11903025)the starting fund of China West Normal University (Grant No.18Q062)+2 种基金the Sichuan Youth Science and Technology Innovation Research Team (Grant No.21CXTD0038)the Chongqing Science and Technology Bureau (Grant No.cstc2022ycjh-bgzxm0161)the Natural Science Foundation of Sichuan Province (Grant No.2022NSFSC1833)。
文摘We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.
文摘Since ancient times,the Chinese New Year has been the most important festival for the Chinese nation,and"celebrating the Chinese New Year in museums"has gradually become a new trend in recent years.To enrich the cultural offerings during the holiday period and let the general audience experience the strong festive atmosphere in museums,on February 22 and 23,2024,on the eve of the Lantern Festival,the China Arts and Crafts Museum(China Intangible Cultural Heritage Museum)successfully held the"Encounter with Intangible Heritage""Capital Colors Shadow Play:Bejing Shadow Puppetry Outreach Activities."
文摘China holds the distinction of hosting the most intangible cultural heritage items in the world,with 43 inscribed on the UNESCO Representative List of Intangible Cultural Heritage of Humanity,including Kunqu Opera,Chinese Shadow Puppetry,and Taijiquan(Tai Chi).However,the knowledge and skills necessary to produce traditional crafts are often reliant on familial and apprenticeship inheritance.
文摘LANGZHONG shadow play has been popular in 36 counties and cities in the vicinity of Langzhong in southwest China’s Sichuan Province,and is one of three major styles of Sichuan shadow play.Around 350 years ago,a puppeteer named Wang Yuansheng created the Langzhong shadow play by combining the unique characteristics of different styles of shadow play with north Sichuan’s folk customs.In 2008,the art of Sichuan shadow play which Langzhong shadow play is affiliated to was listed as a national intangible culture heritage item.
文摘When designing a solar power plant, it is much more important to avoid the shadow on the PV Panels. As the shadow falls on the PV Panels;it significantly reduces the generation of required power as planned and designed. This research paper and case study will help a lot to avoid shadow, especially when selecting inter-row spacing between the strings of solar power plants.
文摘The current academic research on the Dian Shi Zhai Pictorial founded in 1884 has been perfected,but there is very little research on the Flying Shadow Pavilion Pictorial,which can be said to be derived from Dian Shi Zhai Pictorial terms of both content and form,and which was founded by the Haiist painter Wu Youru in 1890 in order to reward the increasing number of admirers,but it is still in the initial stage.Flying Shadow Pavilion Pictorial consisted of four parts:pictures of ladies in Shanghai costumes,news about current affairs,pictures of animals,and compilations of women,each of which was accompanied by the then popular notebooks,which were popular at the time among the then readers because of the matching of pictures with text and the mixing of narratives and discussions.This paper takes Flying Shadow Pavilion Pictorial as the main object,summarizes the existing literature about Flying Shadow Pavilion Pictorial,points out the deficiencies of the current research on this basis,and points out the development trend of Flying Shadow Pavilion Pictorial in the future research.
基金Supported by the National Natral Science Foundation of China (Grant No 60602058)the National High Technology Research and Development Program of China (Grant No 2006AA01Z257)
文摘In this paper, we develop and analyze an energy efficient ARQ (automatic repeat request) initialized transmit diversity protocol for cooperative communications.Medium access control (MAC) layer packet retransmission limit (similar to aShortRetryLimit or aLongRetryLimit [802.11-1997]) has been used as an actuator for transmit cooperative diversity initialization.We take the channel state information (CSI) as a function of retransmission tries and the number of retransmission tries is modeled as a random variable.Relays close to the source node are chosen for the transmit cooperation.Closed form expressions are obtained for symbol error rate (SER), outage capacity and outage probability for the proposed scheme in shadowed fading channels.This cooperative scheme achieves lower signal-to-noise ratio (SNR), stumpy outage probability, higher bandwidth, and transmit energy efficiencies for desired average symbol error rate (ASER) than the preceding ARQ based cooperative protocols.Finally, the results of computer simulations are included to demonstrate the efficacy of the proposed scheme and to verify the accuracy of the analytical expressions.
文摘Accompanied by music,a turtle and a crane fight in a humorous story created by the simple interplay of light and curtain.This Chinese shadow puppetry performance makes the audience laugh.Backstage,Lu Baogang,a national-level inheritor of Beijing shadow puppetry art,and the other performers of the shadow puppetry troupe manipulate the silhouettes with great skill.
基金supported in part by the 14th Five-Year Project of Ministry of Science and Technology of China(2021YFD2000304)Fundamental Research Funds for the Central Universities(531118010509)Natural Science Foundation of Hunan Province,China(2021JJ40114)。
文摘Automatic pavement crack detection is a critical task for maintaining the pavement stability and driving safety.The task is challenging because the shadows on the pavement may have similar intensity with the crack,which interfere with the crack detection performance.Till to the present,there still lacks efficient algorithm models and training datasets to deal with the interference brought by the shadows.To fill in the gap,we made several contributions as follows.First,we proposed a new pavement shadow and crack dataset,which contains a variety of shadow and pavement pixel size combinations.It also covers all common cracks(linear cracks and network cracks),placing higher demands on crack detection methods.Second,we designed a two-step shadow-removal-oriented crack detection approach:SROCD,which improves the performance of the algorithm by first removing the shadow and then detecting it.In addition to shadows,the method can cope with other noise disturbances.Third,we explored the mechanism of how shadows affect crack detection.Based on this mechanism,we propose a data augmentation method based on the difference in brightness values,which can adapt to brightness changes caused by seasonal and weather changes.Finally,we introduced a residual feature augmentation algorithm to detect small cracks that can predict sudden disasters,and the algorithm improves the performance of the model overall.We compare our method with the state-of-the-art methods on existing pavement crack datasets and the shadow-crack dataset,and the experimental results demonstrate the superiority of our method.
基金supported by National Natural Science Foundation of China(12071018)Fundamental Research Funds for the Central Universitiessupported by the National Research Foundation of Korea(NRF)funded by the Korea government(MIST)(2020R1F1A1A01051370)。
文摘In this paper,we define a generalized Lipschitz shadowing property for flows and prove that a flowΦgenerated by a C1vector field X on a closed Riemannian manifold M has this generalized Lipschitz shadowing property if and only if it is structurally stable.
基金funded by the National Natural Science Foundation of China(42077247,52104029)the Fundamental Research Funds for the Central Universities.
文摘In the Changqing Oilfield in northwest China, when traditional petroleum exploitation encounters forestry reserves or water source protection areas, sectorial well-factory design is proposed. The most distinct feature of a sectorial well-factory is the deviation of the well from the minimum horizontal principal stress, resulting in hydraulic fracture deflection after the initiation, along with possible well interference (i.e., fracture hit) and fracture coalescence in the oblique wells. Four indexes describing well deflection are then proposed according to fracture morphology. Several fracturing designs, including stage arrangement, fracturing sequences, and fracturing techniques are applied to study the feasibility of the sectorial well-factory design. The results show that the “gradual” or “sparse” stage arrangement, large injection rate, and simultaneous multifracture treatment can help to optimize the fracture morphology and stimulation design. However, the subsequent stress shadowing effect usually adversely affects the fracturing of adjacent wells. With a small initial horizontal stress difference, large injection rate and staggered stage arrangement can achieve ideal stimulation performance. Our results can provide a guidance for optimizing stimulation design in unconventional well-factory while taking into account environmental protection.
基金supported by the National Natural Science Foundation of China (Grant No.42101403)the National Key Researchand Development Program of China (Grant No.2017YFD0600404)。
文摘Although airborne hyperspectral data with detailed spatial and spectral information has demonstrated significant potential for tree species classification,it has not been widely used over large areas.A comprehensive process based on multi-flightline airborne hyperspectral data is lacking over large,forested areas influenced by both the effects of bidirectional reflectance distribution function(BRDF)and cloud shadow contamination.In this study,hyperspectral data were collected over the Mengjiagang Forest Farm in Northeast China in the summer of 2017 using the Chinese Academy of Forestry's LiDAR,CCD,and hyperspectral systems(CAF-LiCHy).After BRDF correction and cloud shadow detection processing,a tree species classification workflow was developed for sunlit and cloud-shaded forest areas with input features of minimum noise fraction reduced bands,spectral vegetation indices,and texture information.Results indicate that BRDF-corrected sunlit hyperspectral data can provide a stable and high classification accuracy based on representative training data.Cloud-shaded pixels also have good spectral separability for species classification.The red-edge spectral information and ratio-based spectral indices with high importance scores are recommended as input features for species classification under varying light conditions.According to the classification accuracies through field survey data at multiple spatial scales,it was found that species classification within an extensive forest area using airborne hyperspectral data under various illuminations can be successfully carried out using the effective radiometric consistency process and feature selection strategy.
基金supported by the National Natural Science Foundation of China(No.52074305)Henan Scientific and Technological Research Project(No.212102210005)Open Fund of Henan Engineering Laboratory for Photoelectric Sensing and Intelligent Measurement and Control(No.HELPSIMC-2020-00X).
文摘Based on the artificial intelligence algorithm of RetinaNet,we propose the Ghost-RetinaNet in this paper,a fast shadow detection method for photovoltaic panels,to solve the problems of extreme target density,large overlap,high cost and poor real-time performance in photovoltaic panel shadow detection.Firstly,the Ghost CSP module based on Cross Stage Partial(CSP)is adopted in feature extraction network to improve the accuracy and detection speed.Based on extracted features,recursive feature fusion structure ismentioned to enhance the feature information of all objects.We introduce the SiLU activation function and CIoU Loss to increase the learning and generalization ability of the network and improve the positioning accuracy of the bounding box regression,respectively.Finally,in order to achieve fast detection,the Ghost strategy is chosen to lighten the size of the algorithm.The results of the experiment show that the average detection accuracy(mAP)of the algorithm can reach up to 97.17%,the model size is only 8.75 MB and the detection speed is highly up to 50.8 Frame per second(FPS),which can meet the requirements of real-time detection speed and accuracy of photovoltaic panels in the practical environment.The realization of the algorithm also provides new research methods and ideas for fault detection in the photovoltaic power generation system.
基金This work is supported by National Natural Science Foundation of China(Grant:62272109).
文摘Target signal acquisition and detection based on sonar images is a challenging task due to the complex underwater environment.In order to solve the problem that some semantic information in sonar images is lost and model detection performance is degraded due to the complex imaging environment,we proposed a more effective and robust target detection framework based on deep learning,which can make full use of the acoustic shadow information in the forward-looking sonar images to assist underwater target detection.Firstly,the weighted box fusion method is adopted to generate a fusion box by weighted fusion of prediction boxes with high confidence,so as to obtain accurate acoustic shadow boxes.Further,the acoustic shadow box is cut down to get the feature map containing the acoustic shadow information,and then the acoustic shadow feature map and the target information feature map are adaptively fused to make full use of the acoustic shadow feature information.In addition,we introduce a threshold processing module to improve the attention of the model to important feature information.Through the underwater sonar dataset provided by Pengcheng Laboratory,the proposed method improved the average accuracy by 3.14%at the IoU threshold of 0.7,which is better than the current traditional target detection model.
基金supported by the National Natural Science Foundation of China(Grant No.11903025)the Starting Fund of China West Normal University(Grant No.18Q062)+2 种基金the Sichuan Youth Science and Technology Innovation Research Team(Grant No.21CXTD0038)the Chongqing Science and Technology Bureau(Grant No.csts2022ycjh-bgzxm0161)the Natural Science Foundation of Sichuan Province(Grant No.2022NSFSC1833)。
文摘We creatively employ the shadow radius to study the thermodynamics of a charged Ad S black hole with a nonlinear electrodynamics(NLED)term.First,the connection between the shadow radius and event horizon is constructed with the aid of the geodesic analysis.It turns out that the black hole shadow radius shows a positive correlation as a function of the event horizon radius.Then in the shadow context,we find that the black hole temperature and heat capacity can be presented by the shadow radius.Further analysis shows that the shadow radius can work similarly to the event horizon in revealing black hole phase transition process.In this sense,we construct the thermal profile of the charged Ad S black hole with inclusion of the NLED effect.In the P<Pc case,it is found that the N-type trend of the temperature given by the shadow radius is always consistent with that obtained by using the event horizon.Thus,we can conclude for the charged Ad S black hole that the phase transition process can be intuitively presented as the thermal profile in the shadow context.Finally,the effects of NLED are carefully analyzed.
基金the Deanship of Scientific Research at King Khalid University for funding this work through Small Groups Project under Grant Number(241/43)Princess Nourah Bint Abdulrahman University Researchers Supporting Project number(PNURSP2022R319)Princess Nourah Bint Abdulrahman University,Riyadh,Saudi Arabia.The authors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code:(22UQU4340237DSR30).
文摘Nowadays,security plays an important role in Internet of Things(IoT)environment especially in medical services’domains like disease prediction and medical data storage.In healthcare sector,huge volumes of data are generated on a daily basis,owing to the involvement of advanced health care devices.In general terms,health care images are highly sensitive to alterations due to which any modifications in its content can result in faulty diagnosis.At the same time,it is also significant to maintain the delicate contents of health care images during reconstruction stage.Therefore,an encryption system is required in order to raise the privacy and security of healthcare data by not leaking any sensitive data.The current study introduces Improved Multileader Optimization with Shadow Image Encryption for Medical Image Security(IMLOSIE-MIS)technique for IoT environment.The aim of the proposed IMLOSIE-MIS model is to accomplish security by generating shadows and encrypting them effectively.To do so,the presented IMLOSIE-MIS model initially generates a set of shadows for every input medical image.Besides,shadow image encryption process takes place with the help of Multileader Optimization(MLO)withHomomorphic Encryption(IMLO-HE)technique,where the optimal keys are generated with the help of MLO algorithm.On the receiver side,decryption process is initially carried out and shadow image reconstruction process is conducted.The experimentation analysis was carried out on medical images and the results inferred that the proposed IMLOSIE-MIS model is an excellent performer compared to other models.The comparison study outcomes demonstrate that IMLOSIE-MIS model is robust and offers high security in IoT-enabled healthcare environment.
基金funded by the National Natural Science Foundation of China(51866012).
文摘To overcome the problems of natural decreases in power quality,and to eliminate wind speed fluctuation due to wind shear and tower shadow effect arising from wind turbine structural parameters,an improved prediction model accounting for the dual effect of wind shear and tower shadow is,in this paper,built.Compared to the conventional prediction model,the proposed model contains a new constraint condition,which makes the disturbance term caused by the tower shadow effect always negative so that the prediction result is closer to the actual situation.Furthermore,wind turbine structural parameters such as hub height,rotor diameter,the diameter of the tower top,and rotor overhang on wind shear and tower shadow effect are also explored in detail.The results show that the wind shear effect became weaker with the increase in hub height.The hub height is independent of the tower shadow effect.The rotor diameter is positively correlated with the wind shear and tower shadow effect.The tower shadow effect is positively correlated with the diameter of the tower top and negatively correlated with the rotor overhang.