The global existence of the heat flow for harmonic maps from noncompact manifolds is considered. When L^m norm of the gradient of initial data is small, the existence of a global solution is proved.
A weak solution to the heat flow problems is constructed.Nonuniqueness results of such solutions are also shown when the first data is a weak solution to the Euler Lagrange equation but not a weakly stationary soluti...A weak solution to the heat flow problems is constructed.Nonuniqueness results of such solutions are also shown when the first data is a weak solution to the Euler Lagrange equation but not a weakly stationary solution to it.展开更多
Expulsion is an undesired event during resistance spot welding because the weld quality deteriorates. It is the ejection of molten metal from the weld nugget which usually occurs due to applying a high current for a s...Expulsion is an undesired event during resistance spot welding because the weld quality deteriorates. It is the ejection of molten metal from the weld nugget which usually occurs due to applying a high current for a short welding time. Expulsion has a significant impact on the final yield strength of the weld, thus the detection and characterization of expulsion events is significant for the quality assurance of resistance spot welds. In this study, hardness mapping, using a scanning hardness machine, was used as a quality assurance technique for re- sistance spot welding. Hardness tests were conducted on a resistance spot welded sample to prepare a hardness map. The test results showed good correlation between the hardness map and metallographic cross sections. The technique also provided further fundamental understand- ing of the resistance spot welding process, especially regarding the occurrence of expulsion in the nugget.展开更多
A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold toleran...A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold tolerance （CT） at seedling stage and heat tolerance （HT） at anthesis.Survival rate of seedlings （SRS） and spikelet fertility （SF）,the index traits of CT and HT,showed significant differences between the two parents under stresses.A total of four QTLs （qSRS1,qSRS7,qSRS11a and qSRS11b） for CT were identified on chromosomes 1,7,11,and the Xiushui 09 alleles increased SRS at all loci except qSRS7.Four QTLs for SF were identified on chromosomes 4,5,6,and 11.These QTLs could be classified into two major types based on their behaviors under normal and stress conditions.The first was QTL expressed only under normal condition;and the second QTL was apparently stress induced and only expressed under stress.Among them,two QTLs （qSF4 and qSF6） which reduced the trait difference between heat stress and normal conditions must have contributed to HT because of their obvious contribution to trait stability,and the IR2061 allele at the qSF6 and the Xiushui 09 allele at the qSF4 improved HT,respectively.No similar QTL was found between CT at seedling stage and HT at anthesis.Therefore,it is possible to breed a new variety with CT and HT by pyramiding the favorable CT-and HT-improved alleles at above loci from Xiushui 09 and IR2061,respectively,through marker-assisted selection （MAS）.展开更多
近年来,随着图像编辑技术的不断发展,数字图像的知识产权保护形势日益严峻。为有效遏制图像内容的非法窃取、复制与篡改行为,切实保障用户的合法权益,图像拷贝检测作为内容审核体系的关键组成部分,其重要性不言而喻。其中,一种常见的规...近年来,随着图像编辑技术的不断发展,数字图像的知识产权保护形势日益严峻。为有效遏制图像内容的非法窃取、复制与篡改行为,切实保障用户的合法权益,图像拷贝检测作为内容审核体系的关键组成部分,其重要性不言而喻。其中,一种常见的规避检测手段是攻击者将源图像的部分内容巧妙地植入目标图像中,形成“画中画”式的局部拷贝。针对这一挑战,本文提出了一种基于ViT的局部图像拷贝检测算法。该算法旨在利用ViT强大的局部特征提取能力,在原始全局特征的基础上提取出图像的局部特征,揭示图像间潜在的依赖关系,并通过重新排列相关图像的顺序,提高具有更高相似度的图像在检测结果中的排序,从而精准实现对图像局部信息的拷贝检测。本文与基于自监督描述符的图像拷贝检测算法(A Self-Supervised Descriptor for Image Copy Detection)相比,在DISC2021数据集上取得显著提升,局部拷贝图像识别准确率提高10%,μAP(Micro Average Precision)指标提高10%~15%。此外,本文还利用热力图进行了直观的定性分析,证实了ViT能够敏锐地捕捉到图像中存在局部拷贝的区域,进一步验证了算法的有效性。本文提出的基于ViT的局部图像拷贝检测重排序算法能对使用画中画图像增强方式的拷贝图像进行有效检测,并在DISC2021数据集上取得了优异成绩,拓展了数字图像取证领域研究的新思路。展开更多
In the present paper Cauchy integral methods have been applied to derive exact and expressions for Goursat’s function for the first and second fundamental problems of isotropic homogeneous perforated infinite elastic...In the present paper Cauchy integral methods have been applied to derive exact and expressions for Goursat’s function for the first and second fundamental problems of isotropic homogeneous perforated infinite elastic media in the presence of uniform flow of heat. For this, we considered the problem of a thin infinite plate of specific thickness with a curvilinear hole where the origins lie in the hole is conformally mapped outside a unit circle by means of a specific rational mapping. Moreover, the three stress components σxx, σyy and σxy of the boundary value problem in the thermoelasticity plane are obtained. Many special cases of the conformal mapping and four applications for different cases are discussed and many main results are derived from the work.展开更多
Peanut(Arachis hypogaea)is of international importance as a source of oil and protein.Soil salinity is one of themost significant abiotic stress factors affecting the yield and quality of peanuts.This study evaluated ...Peanut(Arachis hypogaea)is of international importance as a source of oil and protein.Soil salinity is one of themost significant abiotic stress factors affecting the yield and quality of peanuts.This study evaluated the potential of a seaweed-based biostimulant to enhance emergence and seedling growth of four peanut cultivars(‘Ayse Hanım’,‘Halis Bey’,‘NC-7’,and‘Albenek’)under increasing salinity levels.The experiment was conducted under greenhouse conditions using a randomized complete block design with four replicates.Seeds were sown in trays and treated with two doses of seaweed extract(0 and 5 g L^(-1))applied directly to the seedbed.Salinity stress was induced by dissolving NaCl in distilled water used for weekly irrigation over six weeks,with salinity levels set at:S_(0):Control,S_(1):50mMNaCl,S_(2):100 mM NaCl,S_(3):150 mM NaCl,and S_(4):200 mM NaCl.Emergence percentage,mean emergence time,shoot and root length,fresh and dry biomass,chlorophyll content,proline,crude protein,and macro-and micronutrient concentrations(Ca,K,P,Mg,Zn,Mn,Cu,and Fe)were measured.The results revealed significant differences between treatments.Seaweed applications showed notable improvements in measured parameters of each variety compared to the salt treated and un-treated control plants of each variety.As salinity stress increased,the emergence percentage,root and shoot length,fresh and dry weight of the plants,crude protein content percentage,leaf chlorophyll contents,Ca,K,P,Mg,Zn,Mn,Cu,and Fe decreased.Similarly,the mean emergence time,and proline contents also decreased with each increase in Na concentration.The best outcomes were obtained in seedlings treated with seaweed under no salinity(0 mM NaCl)and mild salinity(50 mM NaCl)conditions.These findings suggest that seaweeds is an effective biostimulant for improving early-stage growth and stress resilience in peanuts under saline conditions.展开更多
Several initiatives have been made in Egypt to increase the overall production of oil crops,especially sunflower and to close the gap between edible oil production and demand.Field experiments were conducted during th...Several initiatives have been made in Egypt to increase the overall production of oil crops,especially sunflower and to close the gap between edible oil production and demand.Field experiments were conducted during the main seasons of 2022 and 2023 at the agricultural research station of National Research Centre,Nubaria,Egypt to investigate the effects of potassium nitrate (0,20,40,60 kg K_(2)O fed^(-1))(fed=feddan=2.4 ha) and zinc sulfate(0,25,50,75 ppm Zn) on growth,oil yield,nutrients components and chemical composition of sunflower.Results indicated that application of potassium nitrate has a promoted effect on chlorophyll content,growth parameters(Head weight,head diameter and 100 seed weight),protein content,oil yield as well as nutrient content under all applied levels.The data also showed that the highest significant increase occurred with the soil application of 40kg fed^(-1)potassium nitrate combined with 75 ppm Zn foliar spray.Meanwhile,the lowest values were obtained at the control treatment.Therefore,the current study detected that potassium soil addition at 40 kg K_(2)O fed^(-1),besides foliar application with 75 ppm Zn are important to improve the growth,macro-micronutrient,seeds and oil productivity of sunflower crops.Oil yield and nutrient content exhibit a strong positive correlation,with a correlation coefficient of 0.903 for N,0.94 for P,0.962 for K and 0.966 for Zn.This indicates that a higher nutrient percentage is associated with higher oil content of sunflower.Study underscores the importance of comprehending the interplay between potassium and zinc treatments in sunflower plants to enhance growth,yield,and oil production effectively.Understanding these relationships can lead to optimized cultivation practices and improved outcomes in sunflower farming.展开更多
The study of how to “control forming and performance” during the thermal deformation of metal materials has always been a central theme in academic research, particularly in addressing the processing challenges asso...The study of how to “control forming and performance” during the thermal deformation of metal materials has always been a central theme in academic research, particularly in addressing the processing challenges associated with difficult-to-form alloys that possess unique functionalities. However, neither the currently commonly used phenomenological constitutive model, physical constitutive model, Dynamic Material Model (DMM) thermal processing theoretical model, and Ruano-Wadsworth-Sherby (R-W-S) deformation mechanism map model incorporating dislocation density nor the reported machine learning method has established a universal model that can achieve a quantitative description of the process-microstructure-formability of thermal processing. It is only possible first to use modeling research to obtain the law of thermal deformation behavior of alloys and then use the results of microscopic characterization to verify the theory. The research methods lack the characteristics of diagnosis and prediction optimization. This study proposes a machine learning framework for optimizing the random forest (RF) model based on a multivariate decision tree, including microstructure images and hot working process parameter information. It predicts the critical performance parameters, energy dissipation behavior, optimal processing window, and softening mechanism of ternary shape memory alloy Ni_(47)Ti_(33)Hf_(20) in the hot working process. This model has a certain universality. It enables coupled analysis of image information and process parameter data and introduces the calculation and ranking of feature importance, reflecting the applicability of feature values in model construction. Finally, the visualization technique Grad-CAM describes the correlation between the input microscopic image and the output, generating critical hotspots in the heat map. The model of accuracy in predicting the power dissipation rate is confirmed by the grain misorientation angles, thus realizing the establishment of a mechanism-driven model based on the evolution of critical microscopic structures during the thermal deformation of the alloy, which dramatically improves the interpretability of the machine learning model. This machine learning framework provides valuable guidance for quantitatively predicting the thermal deformation processing-microstructure-formability relationship of the Ni_(47)Ti_(33)Hf_(20) shape memory alloy and can potentially be applied to other alloys.展开更多
Taking the Ming Tombs Forest Farm in Beijing as the research object,this research applied multi-source data fusion and GIS heat-map overlay analysis techniques,systematically collected bird observation point data from...Taking the Ming Tombs Forest Farm in Beijing as the research object,this research applied multi-source data fusion and GIS heat-map overlay analysis techniques,systematically collected bird observation point data from the Global Biodiversity Information Facility(GBIF),population distribution data from the Oak Ridge National Laboratory(ORNL)in the United States,as well as information on the composition of tree species in suitable forest areas for birds and the forest geographical information of the Ming Tombs Forest Farm,which is based on literature research and field investigations.By using GIS technology,spatial processing was carried out on bird observation points and population distribution data to identify suitable bird-watching areas in different seasons.Then,according to the suitability value range,these areas were classified into different grades(from unsuitable to highly suitable).The research findings indicated that there was significant spatial heterogeneity in the bird-watching suitability of the Ming Tombs Forest Farm.The north side of the reservoir was generally a core area with high suitability in all seasons.The deep-aged broad-leaved mixed forests supported the overlapping co-existence of the ecological niches of various bird species,such as the Zosterops simplex and Urocissa erythrorhyncha.In contrast,the shallow forest-edge coniferous pure forests and mixed forests were more suitable for specialized species like Carduelis sinica.The southern urban area and the core area of the mausoleums had relatively low suitability due to ecological fragmentation or human interference.Based on these results,this paper proposed a three-level protection framework of“core area conservation—buffer zone management—isolation zone construction”and a spatio-temporal coordinated human-bird co-existence strategy.It was also suggested that the human-bird co-existence space could be optimized through measures such as constructing sound and light buffer interfaces,restoring ecological corridors,and integrating cultural heritage elements.This research provided an operational technical approach and decision-making support for the scientific planning of bird-watching sites and the coordination of ecological protection and tourism development.展开更多
基金Supported by the National Natural Science Foundation of China (1057115610671079+1 种基金10701064)the Zijin Project of Zhejiang University
文摘The global existence of the heat flow for harmonic maps from noncompact manifolds is considered. When L^m norm of the gradient of initial data is small, the existence of a global solution is proved.
文摘A weak solution to the heat flow problems is constructed.Nonuniqueness results of such solutions are also shown when the first data is a weak solution to the Euler Lagrange equation but not a weakly stationary solution to it.
文摘Expulsion is an undesired event during resistance spot welding because the weld quality deteriorates. It is the ejection of molten metal from the weld nugget which usually occurs due to applying a high current for a short welding time. Expulsion has a significant impact on the final yield strength of the weld, thus the detection and characterization of expulsion events is significant for the quality assurance of resistance spot welds. In this study, hardness mapping, using a scanning hardness machine, was used as a quality assurance technique for re- sistance spot welding. Hardness tests were conducted on a resistance spot welded sample to prepare a hardness map. The test results showed good correlation between the hardness map and metallographic cross sections. The technique also provided further fundamental understand- ing of the resistance spot welding process, especially regarding the occurrence of expulsion in the nugget.
基金funded by the Project of the 863 Program(2010AA101803)the 948 Program of China(2006-G51 and 2010-G2B)
文摘A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold tolerance （CT） at seedling stage and heat tolerance （HT） at anthesis.Survival rate of seedlings （SRS） and spikelet fertility （SF）,the index traits of CT and HT,showed significant differences between the two parents under stresses.A total of four QTLs （qSRS1,qSRS7,qSRS11a and qSRS11b） for CT were identified on chromosomes 1,7,11,and the Xiushui 09 alleles increased SRS at all loci except qSRS7.Four QTLs for SF were identified on chromosomes 4,5,6,and 11.These QTLs could be classified into two major types based on their behaviors under normal and stress conditions.The first was QTL expressed only under normal condition;and the second QTL was apparently stress induced and only expressed under stress.Among them,two QTLs （qSF4 and qSF6） which reduced the trait difference between heat stress and normal conditions must have contributed to HT because of their obvious contribution to trait stability,and the IR2061 allele at the qSF6 and the Xiushui 09 allele at the qSF4 improved HT,respectively.No similar QTL was found between CT at seedling stage and HT at anthesis.Therefore,it is possible to breed a new variety with CT and HT by pyramiding the favorable CT-and HT-improved alleles at above loci from Xiushui 09 and IR2061,respectively,through marker-assisted selection （MAS）.
文摘近年来,随着图像编辑技术的不断发展,数字图像的知识产权保护形势日益严峻。为有效遏制图像内容的非法窃取、复制与篡改行为,切实保障用户的合法权益,图像拷贝检测作为内容审核体系的关键组成部分,其重要性不言而喻。其中,一种常见的规避检测手段是攻击者将源图像的部分内容巧妙地植入目标图像中,形成“画中画”式的局部拷贝。针对这一挑战,本文提出了一种基于ViT的局部图像拷贝检测算法。该算法旨在利用ViT强大的局部特征提取能力,在原始全局特征的基础上提取出图像的局部特征,揭示图像间潜在的依赖关系,并通过重新排列相关图像的顺序,提高具有更高相似度的图像在检测结果中的排序,从而精准实现对图像局部信息的拷贝检测。本文与基于自监督描述符的图像拷贝检测算法(A Self-Supervised Descriptor for Image Copy Detection)相比,在DISC2021数据集上取得显著提升,局部拷贝图像识别准确率提高10%,μAP(Micro Average Precision)指标提高10%~15%。此外,本文还利用热力图进行了直观的定性分析,证实了ViT能够敏锐地捕捉到图像中存在局部拷贝的区域,进一步验证了算法的有效性。本文提出的基于ViT的局部图像拷贝检测重排序算法能对使用画中画图像增强方式的拷贝图像进行有效检测,并在DISC2021数据集上取得了优异成绩,拓展了数字图像取证领域研究的新思路。
文摘In the present paper Cauchy integral methods have been applied to derive exact and expressions for Goursat’s function for the first and second fundamental problems of isotropic homogeneous perforated infinite elastic media in the presence of uniform flow of heat. For this, we considered the problem of a thin infinite plate of specific thickness with a curvilinear hole where the origins lie in the hole is conformally mapped outside a unit circle by means of a specific rational mapping. Moreover, the three stress components σxx, σyy and σxy of the boundary value problem in the thermoelasticity plane are obtained. Many special cases of the conformal mapping and four applications for different cases are discussed and many main results are derived from the work.
文摘Peanut(Arachis hypogaea)is of international importance as a source of oil and protein.Soil salinity is one of themost significant abiotic stress factors affecting the yield and quality of peanuts.This study evaluated the potential of a seaweed-based biostimulant to enhance emergence and seedling growth of four peanut cultivars(‘Ayse Hanım’,‘Halis Bey’,‘NC-7’,and‘Albenek’)under increasing salinity levels.The experiment was conducted under greenhouse conditions using a randomized complete block design with four replicates.Seeds were sown in trays and treated with two doses of seaweed extract(0 and 5 g L^(-1))applied directly to the seedbed.Salinity stress was induced by dissolving NaCl in distilled water used for weekly irrigation over six weeks,with salinity levels set at:S_(0):Control,S_(1):50mMNaCl,S_(2):100 mM NaCl,S_(3):150 mM NaCl,and S_(4):200 mM NaCl.Emergence percentage,mean emergence time,shoot and root length,fresh and dry biomass,chlorophyll content,proline,crude protein,and macro-and micronutrient concentrations(Ca,K,P,Mg,Zn,Mn,Cu,and Fe)were measured.The results revealed significant differences between treatments.Seaweed applications showed notable improvements in measured parameters of each variety compared to the salt treated and un-treated control plants of each variety.As salinity stress increased,the emergence percentage,root and shoot length,fresh and dry weight of the plants,crude protein content percentage,leaf chlorophyll contents,Ca,K,P,Mg,Zn,Mn,Cu,and Fe decreased.Similarly,the mean emergence time,and proline contents also decreased with each increase in Na concentration.The best outcomes were obtained in seedlings treated with seaweed under no salinity(0 mM NaCl)and mild salinity(50 mM NaCl)conditions.These findings suggest that seaweeds is an effective biostimulant for improving early-stage growth and stress resilience in peanuts under saline conditions.
文摘Several initiatives have been made in Egypt to increase the overall production of oil crops,especially sunflower and to close the gap between edible oil production and demand.Field experiments were conducted during the main seasons of 2022 and 2023 at the agricultural research station of National Research Centre,Nubaria,Egypt to investigate the effects of potassium nitrate (0,20,40,60 kg K_(2)O fed^(-1))(fed=feddan=2.4 ha) and zinc sulfate(0,25,50,75 ppm Zn) on growth,oil yield,nutrients components and chemical composition of sunflower.Results indicated that application of potassium nitrate has a promoted effect on chlorophyll content,growth parameters(Head weight,head diameter and 100 seed weight),protein content,oil yield as well as nutrient content under all applied levels.The data also showed that the highest significant increase occurred with the soil application of 40kg fed^(-1)potassium nitrate combined with 75 ppm Zn foliar spray.Meanwhile,the lowest values were obtained at the control treatment.Therefore,the current study detected that potassium soil addition at 40 kg K_(2)O fed^(-1),besides foliar application with 75 ppm Zn are important to improve the growth,macro-micronutrient,seeds and oil productivity of sunflower crops.Oil yield and nutrient content exhibit a strong positive correlation,with a correlation coefficient of 0.903 for N,0.94 for P,0.962 for K and 0.966 for Zn.This indicates that a higher nutrient percentage is associated with higher oil content of sunflower.Study underscores the importance of comprehending the interplay between potassium and zinc treatments in sunflower plants to enhance growth,yield,and oil production effectively.Understanding these relationships can lead to optimized cultivation practices and improved outcomes in sunflower farming.
文摘The study of how to “control forming and performance” during the thermal deformation of metal materials has always been a central theme in academic research, particularly in addressing the processing challenges associated with difficult-to-form alloys that possess unique functionalities. However, neither the currently commonly used phenomenological constitutive model, physical constitutive model, Dynamic Material Model (DMM) thermal processing theoretical model, and Ruano-Wadsworth-Sherby (R-W-S) deformation mechanism map model incorporating dislocation density nor the reported machine learning method has established a universal model that can achieve a quantitative description of the process-microstructure-formability of thermal processing. It is only possible first to use modeling research to obtain the law of thermal deformation behavior of alloys and then use the results of microscopic characterization to verify the theory. The research methods lack the characteristics of diagnosis and prediction optimization. This study proposes a machine learning framework for optimizing the random forest (RF) model based on a multivariate decision tree, including microstructure images and hot working process parameter information. It predicts the critical performance parameters, energy dissipation behavior, optimal processing window, and softening mechanism of ternary shape memory alloy Ni_(47)Ti_(33)Hf_(20) in the hot working process. This model has a certain universality. It enables coupled analysis of image information and process parameter data and introduces the calculation and ranking of feature importance, reflecting the applicability of feature values in model construction. Finally, the visualization technique Grad-CAM describes the correlation between the input microscopic image and the output, generating critical hotspots in the heat map. The model of accuracy in predicting the power dissipation rate is confirmed by the grain misorientation angles, thus realizing the establishment of a mechanism-driven model based on the evolution of critical microscopic structures during the thermal deformation of the alloy, which dramatically improves the interpretability of the machine learning model. This machine learning framework provides valuable guidance for quantitatively predicting the thermal deformation processing-microstructure-formability relationship of the Ni_(47)Ti_(33)Hf_(20) shape memory alloy and can potentially be applied to other alloys.
基金Sponsored by Beijing Youth Innovation Talent Support Program for Urban Greening and Landscaping——The 2024 Special Project for Promoting High-Quality Development of Beijing’s Landscaping through Scientific and Technological Innovation(KJCXQT202410).
文摘Taking the Ming Tombs Forest Farm in Beijing as the research object,this research applied multi-source data fusion and GIS heat-map overlay analysis techniques,systematically collected bird observation point data from the Global Biodiversity Information Facility(GBIF),population distribution data from the Oak Ridge National Laboratory(ORNL)in the United States,as well as information on the composition of tree species in suitable forest areas for birds and the forest geographical information of the Ming Tombs Forest Farm,which is based on literature research and field investigations.By using GIS technology,spatial processing was carried out on bird observation points and population distribution data to identify suitable bird-watching areas in different seasons.Then,according to the suitability value range,these areas were classified into different grades(from unsuitable to highly suitable).The research findings indicated that there was significant spatial heterogeneity in the bird-watching suitability of the Ming Tombs Forest Farm.The north side of the reservoir was generally a core area with high suitability in all seasons.The deep-aged broad-leaved mixed forests supported the overlapping co-existence of the ecological niches of various bird species,such as the Zosterops simplex and Urocissa erythrorhyncha.In contrast,the shallow forest-edge coniferous pure forests and mixed forests were more suitable for specialized species like Carduelis sinica.The southern urban area and the core area of the mausoleums had relatively low suitability due to ecological fragmentation or human interference.Based on these results,this paper proposed a three-level protection framework of“core area conservation—buffer zone management—isolation zone construction”and a spatio-temporal coordinated human-bird co-existence strategy.It was also suggested that the human-bird co-existence space could be optimized through measures such as constructing sound and light buffer interfaces,restoring ecological corridors,and integrating cultural heritage elements.This research provided an operational technical approach and decision-making support for the scientific planning of bird-watching sites and the coordination of ecological protection and tourism development.
