The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural ...The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural analysis,the welded joints exhibit distinct microstructural zones,including the stir zone(SZ),thermomechanically affected zone(TMAZ),and heat-affected zone(HAZ).The grain size of each zone is in the order of HAZ>TMAZ>SZ.Notably,the TMAZ and HAZ contain significantly larger secondary-phase particles compared to the SZ,with particle size in the HAZ increasing at higher rotational speeds.Electrochemical tests indicate that corrosion susceptibility follows the sequence of HAZ>TMAZ>SZ>BM,with greater sensitivity observed at increased rotational speeds.Post-corrosion mechanical performance degradation primarily arises from crevice corrosion at joint overlaps,but not from the changes in the microstructure.展开更多
Using seismic attributes as features for classification in feature space, in various aims such as seismic facies analysis, is conventional for the purpose of seismic interpretation. But sometimes seismic data may have...Using seismic attributes as features for classification in feature space, in various aims such as seismic facies analysis, is conventional for the purpose of seismic interpretation. But sometimes seismic data may have no attributes or it is hard to define a small and relevant set of attributes in some applica- tions. Therefore, employing techniques that perform facies modeling without using attributes is neces- sary. In this paper we present a new method for facies modeling of seismic data with missing attributes that called dissimilarity based classification. In this method, classification is based on dissimilarities and facies modeling will be done in dissimilarity space. In this space dissimilarities consider as new features instead of real features. A support vector machine as a powerful classifier was employed in both feature space （feature-based） and dissimilarity space （feature-less） for facies analysis. The proposed feature-less and feature-based classification is applied on a real seismic data from an Iranian oil field. Facies model- ing using seismic attributes provide better results, but the feature-less classification outcome is also satis- factory and the facies correlation is acceptable. Indeed, the power of attributes to discriminate different facies causes to that facies analysis using attributes provide more reliable results comparing to feature- less facies analysis.展开更多
In this paper the authors study the sample behavior of the Gini’s index of dissimilarity in the case of two samples of equal size drawn from the same uniform population. The paper present the analytical results obtai...In this paper the authors study the sample behavior of the Gini’s index of dissimilarity in the case of two samples of equal size drawn from the same uniform population. The paper present the analytical results obtained for the exact distribution of the index of dissimilarity for sample sizes n ≤ 8. This result was obtained by expressing the index of dissimilarity as a linear combination of spacings of the pooled sample. The obtained results allow to achieve the exact expressions of the moments for any sample size and, therefore, to highlight the main features of the sampling distributions of the index of dissimilarity. The present study can enhance inferential statistical aspects about one of the main contributions of Gini.展开更多
More accurate and reliable estimation of residual strength friction angle(/r)of clay is crucial in many geotechnical engineering applications,including riverbank stability analysis,design,and assessment of earthen dam...More accurate and reliable estimation of residual strength friction angle(/r)of clay is crucial in many geotechnical engineering applications,including riverbank stability analysis,design,and assessment of earthen dam slope stabilities.However,a general predictive equation for/r,with applicability in a wide range of effective parameters,remains an important research gap.The goal of this study is to develop a more accurate equation for/r using the Pareto Optimal Multi-gene Genetic Programming(POMGGP)approach by evaluating a comprehensive dataset of 290 experiments compiled from published literature databases worldwide.A new framework for integrated equation derivation proposed that hybridizes the Subset Selection of Maximum Dissimilarity Method(SSMD)with Multi-gene Genetic Programming(MGP)and Pareto-optimality(PO)to find an accurate equation for/r with wide range applicability.The final predictive equation resulted from POMGGP modeling was assessed in comparison with some previously published machine learning-based equations using statistical error analysis criteria,Taylor diagram,revised discrepancy ratio(RDR),and scatter plots.Base on the results,the POMGGP has the lowest uncertainty with U95=2.25,when compared with Artificial Neural Network(ANN)(U95=2.3),Bayesian Regularization Neural Network(BRNN)(U95=2.94),Levenberg-Marquardt Neural Network(LMNN)(U95=3.3),and Differential Evolution Neural Network(DENN)(U95=2.37).The more reliable results in estimation of/r derived by POMGGP with reliability 59.3%,and resiliency 60%in comparison with ANN(reliability=30.23%,resiliency=28.33%),BRNN(reliability=10.47%,resiliency=10.39%),LMNN(reliability=19.77%,resiliency=20.29%)and DENN(reliability=27.91%,resiliency=24.19%).Besides the simplicity and ease of application of the new POMGGP equation to a broad range of conditions,using the uncertainty,reliability,and resilience analysis confirmed that the derived equation for/r significantly outperformed other existing machine learning methods,including the ANN,BRNN,LMNN,and DENN equations。展开更多
This paper investigates how the chair-CEO age dissimilarity and CEO power affect the dispersion and change of chair-CEO pay gap from both static and dynamic perspectives.The substantial age dissimilarity between the c...This paper investigates how the chair-CEO age dissimilarity and CEO power affect the dispersion and change of chair-CEO pay gap from both static and dynamic perspectives.The substantial age dissimilarity between the chairman and the CEO gives rise to cognitive conflict,thereby increasing board monitoring for firms with greater monitoring needs.Using data of China s listed firms from 2009 to 2017,we find a significant negative effect of CEO power on pay gap between the chairman and the CEO.In addition,when CEO is a member of the board or compensation committee,the power of CEO has different influences on the compensation,but the cognitive conflicts caused by chair-CEO age dissimilarity always inhibit the CEO s power.Thus,age dissimilarity has become an important complement to the board s regulatory mechanisms.展开更多
In this paper the authors study empirically the power of the test based on the index of dissimilarity to compare two samples drawn from two populations differing only in the location parameter. We call such a test as ...In this paper the authors study empirically the power of the test based on the index of dissimilarity to compare two samples drawn from two populations differing only in the location parameter. We call such a test as test of homogeneity. In practice the power of such a bidirectional test will be studied referring to the absolute value of the shiftδand to the same probability models considered by Fried and Dehling.展开更多
Leymus chinensis （Trin.） Tzvel is the characteristic of the Eastern Asia, and is a perennial herbaceous rhizome species on L. chinensis steppe of the Northern China, the Eastern Mongolia, and area of Outer-Baikal of...Leymus chinensis （Trin.） Tzvel is the characteristic of the Eastern Asia, and is a perennial herbaceous rhizome species on L. chinensis steppe of the Northern China, the Eastern Mongolia, and area of Outer-Baikal of Russia. It has both vegetative and sexual reproductions, and results in complexity of the population structure. Thus, it is difficult to identify distinct clones. Author used the randomly amplified polymorphic DNA （RAPD） technique to identify the clonal structure of heterogeneous and homogeneous habitats in two populations ofLeymus chinensis, analyzed 260 ramets samples using 12 primers and 60 polymorphie markers （reproducible RAPD bands）. The results proved elonal diversity described using PD, D, and E was higher in the HCS habitat than that in the HPS habitat. The PD, D, and E in the HCS of Songzhan population were 0.21, 0.90, and 0.91, respectively, whereas the PD, D, and E in the HPS of Songzhan population were only 0.09, 0.68, and 0.77, respectively; the PD, D, and E in the HCS of Yongle population were 0.19, 0.92 mad 0.90, respectively, correspondingly, these measures in the HPS of Yongle population were only 0.09, 0.63, and 0.79, respectively. The results also indicated that clonal population ofL. chinensis in HPS habitat had lower genetic dissimilarity index than that in the HCS habitat.展开更多
Similarity coefficient mapping（SCM） aims to improve the morphological evaluation of T＊2weighted magnetic resonance imaging（T＊2-w MRI）. However, how to interpret the generated SCM map is still pending. Moreover, ...Similarity coefficient mapping（SCM） aims to improve the morphological evaluation of T＊2weighted magnetic resonance imaging（T＊2-w MRI）. However, how to interpret the generated SCM map is still pending. Moreover, is it probable to extract tissue dissimilarity messages based on the theory behind SCM？ The primary purpose of this paper is to address these two questions. First, the theory of SCM was interpreted from the perspective of linear fitting. Then, a term was embedded for tissue dissimilarity information. Finally, our method was validated with sixteen human brain image series from multiecho T＊2-w MRI. Generated maps were investigated from signal-to-noise ratio（SNR） and perceived visual quality, and then interpreted from intra- and inter-tissue intensity. Experimental results show that both perceptibility of anatomical structures and tissue contrast are improved. More importantly, tissue similarity or dissimilarity can be quantified and cross-validated from pixel intensity analysis. This method benefits image enhancement, tissue classification, malformation detection and morphological evaluation.展开更多
A novel 3-D graphical representation of protein sequence has been introduced. A right cone of a unit base and unit height has been selected to represent protein sequences on its surface. The twenty amino acids have be...A novel 3-D graphical representation of protein sequence has been introduced. A right cone of a unit base and unit height has been selected to represent protein sequences on its surface. The twenty amino acids have been represented by 20 circles and all protein's residues have been represented by n lines on the cone's surface. All the spots which represent the protein's residues have been shown in the cone's top view. The spatial median of all the spots is used as a new descriptor of any protein sequence. This approach was applied on two short segments of protein of yeast Saccharomyces cerevisiae. The examination of the similarities/dissimilarities for the eight ND5 proteins and the six β-globin proteins illustrate the utility of our approach. A linear correlation and significance analysis have been provided to compare our results and the percentage sequence alignment identity.展开更多
Systems engineering is not a new discipline. However, up to now, there is little consensus on its exact definition and scope. The scopes of several disciplines (neighboring disciplines of systems engineering) overlap ...Systems engineering is not a new discipline. However, up to now, there is little consensus on its exact definition and scope. The scopes of several disciplines (neighboring disciplines of systems engineering) overlap with that of systems engineering. In this paper, the methods to identify similarities and dissimilarities between systems engineering and its neighboring disciplines are discussed. The research of this paper is expected to be helpful for clarifying the definition and scope of systems engineering.展开更多
Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with ...Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with the decrease in welding heat input,the weld surface is smoother.The Ti/Al joint interface is flat without obvious Ti and Al mixed structure,and the hook structure is not formed under optimal parameters.Due to the enhanced breaking effect of the stirring head,the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min,thereby deteriorating the mechanical properties of joints.Decreasing the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget zone.Under the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min,the maximum tensile shear strength of joint is 289 N/mm.展开更多
The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion...The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.展开更多
Chinese painting has a long history and distinctive national characteristics, self-contained in the field of world art. It is unique and become the mainstream of oriental art. Traditional Chinese painting is artistic ...Chinese painting has a long history and distinctive national characteristics, self-contained in the field of world art. It is unique and become the mainstream of oriental art. Traditional Chinese painting is artistic conception as the soul, melting into poetry, books, paintings as a whole, poetic romance as the connotation, expressing feelings and thoughts. It exhibited virtual static beauty in thinking of Taoist philosophy of nature, becoming a unique Chinese aesthetic art. Artistic spirit is an important part and aesthetic standard of Chinese painting aesthetics, in the ＂paintings goods recorded,＂ ＂Lively spirit＂ is defined as the highest state of painting, artistic spirit is not a very mysterious thing, it was born from the pen and ink. NO pen and ink, no artistic spirit. Pursuing vivid artistic spirit, emphasizing ink skills, giving vent to feelings of oneself for its purpose, Chinese painting has generated a large number of outstanding works of art in thousands of years, constructed a unique cultural spirit, shaped the nation ＇ s aesthetic temperament and character.展开更多
The layer-by-layer deposition strategy of additive manufacturing makes it ideal to fabricate dissimilar alloy components with varying functionality,which has promising application potential in a large number of indust...The layer-by-layer deposition strategy of additive manufacturing makes it ideal to fabricate dissimilar alloy components with varying functionality,which has promising application potential in a large number of industrial areas.In this study,two components composed of ERCuAl-A2 aluminum bronze(CuAl9)and Inconel 718 nickel-based superalloy were fabricated with different deposition orders by wire-arc directed energy deposition.Subject to changes in heat input and thermophysical properties of the substrate,the transition region of the deposited Cu-Ni component with the bottom half of CuAl9 and the top half of Inconel 718 is narrow and serrated.This region features a laminated intermetallic compound layer due to the convection and rapid cooling in the molten pool.In contrast,the Ni-Cu component deposited in the opposite order exhibits a 2 mm gradient transition zone.Within this region,a large number of diverse precipitates were found as well as regional variations in grain size due to the multi-layer partial remelting.Both two components show strong bonds and their tensile specimens tested along the vertical direction always fracture at the softer CuAl9 side.Excellent tensile properties along the horizontal direction were obtained for Cu-Ni(Ultimate tensile strength:573 MPa,yield stress:302 MPa,elongation:22%),while those of Ni-Cu are much lower due to the existence of the solidification cracks in the transition zone.The results from this study provide a reference for the additive manufacturing of Cu/Ni dissimilar alloy components,as well as their microstructure and mechanical properties control.展开更多
The lamellar layer of intermetallic compounds(IMCs)was adversely affected the performance of welding-brazing joints in Al/steel dissimilar metals.In this study,a short fiber-like surface morphology was fabricated on t...The lamellar layer of intermetallic compounds(IMCs)was adversely affected the performance of welding-brazing joints in Al/steel dissimilar metals.In this study,a short fiber-like surface morphology was fabricated on the butt surface of Q235 steel via laser.The interaction behavior between the short fibers and the molten pool was captured using a high-speed camera.Laser-arc hybrid welding-brazing was then employed to join Al(6061-T6)to the steel.This process successfully created a short fiber-like interface structure at the joint.The relationship between microstructure and mechanical properties was investigated,compared with Al/bare steel(ABS)joint.The research results indicated that the IMCs layer consisted of FeAl_(3)and Fe_(2)Al_(5).The interface strength of the Al/short fiber-like surface structural steel(ASFSSS)joint reached 153.2 MPa,an 82.2%increase compared to the ABS joint,which reached 84.1 MPa.When the ASFSSS joints without the reinforcement were bent to 58.2°and 25.2°in the longitudinal and transverse direction,respectively,they remained intact.However,cracks were discovered when the bending angle of the ABS reached 39.1°and 0°in the two directions.Numerical simulation revealed that the short fiber-like interface structure significantly reduced residual stress and improved the stress distribution in the weld,thereby enhancing the strength and toughness of Al/steel dissimilar joints.The crack propagation path in the ASFSSS joint was deflected into the weld when it encountered short fibers,and the fracture morphology presented the characteristic of ductile-brittle mixed fracture.展开更多
Friction stir lap welding(FSLW)was adopted to join successfully dissimilar AZ31B Mg alloy and TC4 Ti alloy with Sn foil addition of 30μm thickness.Interfacial microstructure,tensile shear performances and bonding mec...Friction stir lap welding(FSLW)was adopted to join successfully dissimilar AZ31B Mg alloy and TC4 Ti alloy with Sn foil addition of 30μm thickness.Interfacial microstructure,tensile shear performances and bonding mechanism of the joints obtained using three different rotation speeds were studied.High-performance FSLW Mg/Ti dissimilar joints with maximum tensile shear strength of 593.3 N/mm were produced at 1180 r/min,and which was mainly attributed to ultrastrong reaction interlayer consisting of 125.9 nm thick(Mg_(2)Sn+Mg)transition layer and discontinuous(Ti_(6)Sn_(5)+Ti_(3)Al)IMCs layer with 6.58 nm thickness at the interface.The formation of the reaction interlayer was beneficial for high interfacial strength,resulting in significantly improving the joint strength.The fracture of all FSLW joints located on AZ31B Mg stirred zone adjacent to(Mg_(2)Sn+Mg)transition layer or along the crack propagation direction of the AZ31B/TC4 interface with different fracture mechanisms,and which could be consistent with interfacial microstructure.展开更多
Plasma electrolytic oxidation(PEO)processing of light metals has been established for decades and is in increasing industrial use,even as an alternative surface treatment to produce multifunctional coatings with envir...Plasma electrolytic oxidation(PEO)processing of light metals has been established for decades and is in increasing industrial use,even as an alternative surface treatment to produce multifunctional coatings with environmental-friendly processing concept.One of the benefits of PEO processing claimed already a couple of years ago was the ability to treat dissimilar metal joints,which can obviously improve the surface homogeneity and stability at the interface of the dissimilar components,especially impeding the galvanic corrosion due to the different electrochemical properties of each component.However,the progress and breakthrough develop slowly especially for the macro scales due to the much larger gap between each component.This literature review firstly demonstrates the still low number of studies reporting successful PEO treatment of material combination such as Mg/Al,Mg/Ti,Al/Ti and scarcely light metal combinations with steel.The main issues and challenges to performing PEO processing on the macroscale dissimilar weldments were stated.On the other hand,dissimilar metal joints also widely exist in micrometer scale in alloys and metal matrix composites(MMCs).Moreover,there is a huge knowledge base on PEO treatment of such multiphase substrates.PEO processing of such complicated mixed microstructures is reviewed as well to reveal the basic problems.To some certain degree,these PEO-related studies on alloys and MMCs can be good examples to have an insight into the coating formation mechanism on macro-scaled dissimilar metal joints.Conclusions are drawn from the micro-to macroscale.Finally,critical access to the problems is given and possible solutions and reaming limitations are discussed.展开更多
The study aimed to address the issue of elevated residual stress levels in dissimilar girth welds of cast steel joints.To achieve this,the hybrid welding technology,which yields high welding speeds while simultaneousl...The study aimed to address the issue of elevated residual stress levels in dissimilar girth welds of cast steel joints.To achieve this,the hybrid welding technology,which yields high welding speeds while simultaneously reducing residual stresses,has been introduced.This study utilizes a numerical simulation method to investigate the temperature and residual stress field in the hybrid welding of G20Mn5 casting-Q355 low-alloy steel welded pipe.A com-parison of the findings of this study with those of other welding processes revealed the technological advantages of hybrid welding.The research outcomes show that due to geometric discontinuities and material differences,the temperature field of the joint exhibits uneven distribution characteristics,and the peak temperatures on the Q355 steel side exceeds those on the G20Mn5 steel side.An evident stress gra-dient is present in the residual stress field of the joint post-welding,with peak stress located at the weld root on the Q355 steel.Compared with arc welding,the hybrid welding leads to decreased residual stresses and deformation,with high stress outside the heat-affected zone diminishing rapidly.Furthermore,it significantly improves the welding efficiency.This study elucidates the distribution and underlying causes of thermal and residual stress fields in dissimilar girth welds.This serves as a foundation for the application of hybrid welding technology in welded cast steel joints.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 52075449, 51975480)。
文摘The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural analysis,the welded joints exhibit distinct microstructural zones,including the stir zone(SZ),thermomechanically affected zone(TMAZ),and heat-affected zone(HAZ).The grain size of each zone is in the order of HAZ>TMAZ>SZ.Notably,the TMAZ and HAZ contain significantly larger secondary-phase particles compared to the SZ,with particle size in the HAZ increasing at higher rotational speeds.Electrochemical tests indicate that corrosion susceptibility follows the sequence of HAZ>TMAZ>SZ>BM,with greater sensitivity observed at increased rotational speeds.Post-corrosion mechanical performance degradation primarily arises from crevice corrosion at joint overlaps,but not from the changes in the microstructure.
基金the Institute of Geophysics,University of Tehran for its valuable support
文摘Using seismic attributes as features for classification in feature space, in various aims such as seismic facies analysis, is conventional for the purpose of seismic interpretation. But sometimes seismic data may have no attributes or it is hard to define a small and relevant set of attributes in some applica- tions. Therefore, employing techniques that perform facies modeling without using attributes is neces- sary. In this paper we present a new method for facies modeling of seismic data with missing attributes that called dissimilarity based classification. In this method, classification is based on dissimilarities and facies modeling will be done in dissimilarity space. In this space dissimilarities consider as new features instead of real features. A support vector machine as a powerful classifier was employed in both feature space （feature-based） and dissimilarity space （feature-less） for facies analysis. The proposed feature-less and feature-based classification is applied on a real seismic data from an Iranian oil field. Facies model- ing using seismic attributes provide better results, but the feature-less classification outcome is also satis- factory and the facies correlation is acceptable. Indeed, the power of attributes to discriminate different facies causes to that facies analysis using attributes provide more reliable results comparing to feature- less facies analysis.
文摘In this paper the authors study the sample behavior of the Gini’s index of dissimilarity in the case of two samples of equal size drawn from the same uniform population. The paper present the analytical results obtained for the exact distribution of the index of dissimilarity for sample sizes n ≤ 8. This result was obtained by expressing the index of dissimilarity as a linear combination of spacings of the pooled sample. The obtained results allow to achieve the exact expressions of the moments for any sample size and, therefore, to highlight the main features of the sampling distributions of the index of dissimilarity. The present study can enhance inferential statistical aspects about one of the main contributions of Gini.
文摘More accurate and reliable estimation of residual strength friction angle(/r)of clay is crucial in many geotechnical engineering applications,including riverbank stability analysis,design,and assessment of earthen dam slope stabilities.However,a general predictive equation for/r,with applicability in a wide range of effective parameters,remains an important research gap.The goal of this study is to develop a more accurate equation for/r using the Pareto Optimal Multi-gene Genetic Programming(POMGGP)approach by evaluating a comprehensive dataset of 290 experiments compiled from published literature databases worldwide.A new framework for integrated equation derivation proposed that hybridizes the Subset Selection of Maximum Dissimilarity Method(SSMD)with Multi-gene Genetic Programming(MGP)and Pareto-optimality(PO)to find an accurate equation for/r with wide range applicability.The final predictive equation resulted from POMGGP modeling was assessed in comparison with some previously published machine learning-based equations using statistical error analysis criteria,Taylor diagram,revised discrepancy ratio(RDR),and scatter plots.Base on the results,the POMGGP has the lowest uncertainty with U95=2.25,when compared with Artificial Neural Network(ANN)(U95=2.3),Bayesian Regularization Neural Network(BRNN)(U95=2.94),Levenberg-Marquardt Neural Network(LMNN)(U95=3.3),and Differential Evolution Neural Network(DENN)(U95=2.37).The more reliable results in estimation of/r derived by POMGGP with reliability 59.3%,and resiliency 60%in comparison with ANN(reliability=30.23%,resiliency=28.33%),BRNN(reliability=10.47%,resiliency=10.39%),LMNN(reliability=19.77%,resiliency=20.29%)and DENN(reliability=27.91%,resiliency=24.19%).Besides the simplicity and ease of application of the new POMGGP equation to a broad range of conditions,using the uncertainty,reliability,and resilience analysis confirmed that the derived equation for/r significantly outperformed other existing machine learning methods,including the ANN,BRNN,LMNN,and DENN equations。
基金National Social Science Fund of China(No.15BGL063)Philosophy Social Science Foundation in Colleges and Universities in Jiangsu Province,China(No.2017SJB0820)
文摘This paper investigates how the chair-CEO age dissimilarity and CEO power affect the dispersion and change of chair-CEO pay gap from both static and dynamic perspectives.The substantial age dissimilarity between the chairman and the CEO gives rise to cognitive conflict,thereby increasing board monitoring for firms with greater monitoring needs.Using data of China s listed firms from 2009 to 2017,we find a significant negative effect of CEO power on pay gap between the chairman and the CEO.In addition,when CEO is a member of the board or compensation committee,the power of CEO has different influences on the compensation,but the cognitive conflicts caused by chair-CEO age dissimilarity always inhibit the CEO s power.Thus,age dissimilarity has become an important complement to the board s regulatory mechanisms.
文摘In this paper the authors study empirically the power of the test based on the index of dissimilarity to compare two samples drawn from two populations differing only in the location parameter. We call such a test as test of homogeneity. In practice the power of such a bidirectional test will be studied referring to the absolute value of the shiftδand to the same probability models considered by Fried and Dehling.
基金Supported by the National Natural Foundation of China (30670336, 30870423, 30870391)
文摘Leymus chinensis （Trin.） Tzvel is the characteristic of the Eastern Asia, and is a perennial herbaceous rhizome species on L. chinensis steppe of the Northern China, the Eastern Mongolia, and area of Outer-Baikal of Russia. It has both vegetative and sexual reproductions, and results in complexity of the population structure. Thus, it is difficult to identify distinct clones. Author used the randomly amplified polymorphic DNA （RAPD） technique to identify the clonal structure of heterogeneous and homogeneous habitats in two populations ofLeymus chinensis, analyzed 260 ramets samples using 12 primers and 60 polymorphie markers （reproducible RAPD bands）. The results proved elonal diversity described using PD, D, and E was higher in the HCS habitat than that in the HPS habitat. The PD, D, and E in the HCS of Songzhan population were 0.21, 0.90, and 0.91, respectively, whereas the PD, D, and E in the HPS of Songzhan population were only 0.09, 0.68, and 0.77, respectively; the PD, D, and E in the HCS of Yongle population were 0.19, 0.92 mad 0.90, respectively, correspondingly, these measures in the HPS of Yongle population were only 0.09, 0.63, and 0.79, respectively. The results also indicated that clonal population ofL. chinensis in HPS habitat had lower genetic dissimilarity index than that in the HCS habitat.
基金Project supported in part by the National High Technology Research and Development Program of China(Grant Nos.2015AA043203 and 2012AA02A604)the National Natural Science Foundation of China(Grant Nos.81171402+8 种基金61471349and 81501463)the Innovative Research Team Program of Guangdong Province,China(Grant No.2011S013)the Science and Technological Program for Higher Education,Science and Researchand Health Care Institutions of Guangdong ProvinceChina(Grant No.2011108101001)the Natural Science Foundation of Guangdong Province,China(Grant No.2014A030310360)the Fundamental Research Program of Shenzhen City,China(Grant No.JCYJ20140417113430639)Beijing Center for Mathematics and Information Interdisciplinary Sciences,China
文摘Similarity coefficient mapping（SCM） aims to improve the morphological evaluation of T＊2weighted magnetic resonance imaging（T＊2-w MRI）. However, how to interpret the generated SCM map is still pending. Moreover, is it probable to extract tissue dissimilarity messages based on the theory behind SCM？ The primary purpose of this paper is to address these two questions. First, the theory of SCM was interpreted from the perspective of linear fitting. Then, a term was embedded for tissue dissimilarity information. Finally, our method was validated with sixteen human brain image series from multiecho T＊2-w MRI. Generated maps were investigated from signal-to-noise ratio（SNR） and perceived visual quality, and then interpreted from intra- and inter-tissue intensity. Experimental results show that both perceptibility of anatomical structures and tissue contrast are improved. More importantly, tissue similarity or dissimilarity can be quantified and cross-validated from pixel intensity analysis. This method benefits image enhancement, tissue classification, malformation detection and morphological evaluation.
文摘A novel 3-D graphical representation of protein sequence has been introduced. A right cone of a unit base and unit height has been selected to represent protein sequences on its surface. The twenty amino acids have been represented by 20 circles and all protein's residues have been represented by n lines on the cone's surface. All the spots which represent the protein's residues have been shown in the cone's top view. The spatial median of all the spots is used as a new descriptor of any protein sequence. This approach was applied on two short segments of protein of yeast Saccharomyces cerevisiae. The examination of the similarities/dissimilarities for the eight ND5 proteins and the six β-globin proteins illustrate the utility of our approach. A linear correlation and significance analysis have been provided to compare our results and the percentage sequence alignment identity.
文摘Systems engineering is not a new discipline. However, up to now, there is little consensus on its exact definition and scope. The scopes of several disciplines (neighboring disciplines of systems engineering) overlap with that of systems engineering. In this paper, the methods to identify similarities and dissimilarities between systems engineering and its neighboring disciplines are discussed. The research of this paper is expected to be helpful for clarifying the definition and scope of systems engineering.
基金National Natural Science Foundation of China(52275349)Key Research and Development Program of Shandong Province(2021ZLGX01)。
文摘Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with the decrease in welding heat input,the weld surface is smoother.The Ti/Al joint interface is flat without obvious Ti and Al mixed structure,and the hook structure is not formed under optimal parameters.Due to the enhanced breaking effect of the stirring head,the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min,thereby deteriorating the mechanical properties of joints.Decreasing the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget zone.Under the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min,the maximum tensile shear strength of joint is 289 N/mm.
基金financially supported by the Science and Technology Innovation Program of Hunan Province,China(No.2023RC3055)the Natural Science Foundation of Hunan Province,China(Nos.2023JJ30671,2020JJ4114)+5 种基金the Natural Science Foundation of Changsha City,China(No.Kq2208264)National Key Project of Research and Development Plan of China(Nos.2021YFC1910505,2021YFC1910504)the Young Core Teacher Foundation of Hunan Province,China(No.150220001)Key Research and Development Program of Guangdong Province,China(No.2020B010186002)the National Natural Science Foundation of China(No.51601229)the Key-Area Research and Development Program of Foshan City,China(No.2230032004640).
文摘The corrosion behavior and microstructure characteristics of metal inert gas(MIG)welded dissimilar joints of the 6005A alloy modified with Sc(designated as 6005A+Sc)and the 5083 alloy were investigated using corrosion tests and microscopy techniques.Results show that the dissimilar joints exhibit strong stress corrosion cracking(SCC)resistance,maintaining substantial strength during slow strain rate tensile tests.Notably,the heat-affected zone(HAZ)and base metal(BM)on the 6005A+Sc side show superior performance in terms of inter-granular corrosion(IGC)and exfoliation corrosion(EXCO)compared to the corresponding zones on the 5083 side.The lower corrosion resistance of the 5083-BM and the 5083-HAZ can be attributed to the presence of numerous Al_(2)Mg_(3)phases and micro-scaled Al_(6)(Mn,Fe)intermetallics,mainly distributed along the rolling direction.Conversely,the enhanced corrosion resistance of the 6005A+Sc-BM and the 6005A+Sc-HAZ can be attributed to the discontinuously distributed grain boundary precipitates(β-Mg_(2)Si),the smaller grain size,and the reduced corrosive current density.
文摘Chinese painting has a long history and distinctive national characteristics, self-contained in the field of world art. It is unique and become the mainstream of oriental art. Traditional Chinese painting is artistic conception as the soul, melting into poetry, books, paintings as a whole, poetic romance as the connotation, expressing feelings and thoughts. It exhibited virtual static beauty in thinking of Taoist philosophy of nature, becoming a unique Chinese aesthetic art. Artistic spirit is an important part and aesthetic standard of Chinese painting aesthetics, in the ＂paintings goods recorded,＂ ＂Lively spirit＂ is defined as the highest state of painting, artistic spirit is not a very mysterious thing, it was born from the pen and ink. NO pen and ink, no artistic spirit. Pursuing vivid artistic spirit, emphasizing ink skills, giving vent to feelings of oneself for its purpose, Chinese painting has generated a large number of outstanding works of art in thousands of years, constructed a unique cultural spirit, shaped the nation ＇ s aesthetic temperament and character.
基金supported by the Key Research and Development Program of Shaanxi Province(2023-YBGY361)the National Natural Science Foundation of China(52275374 and 52205414)+1 种基金the Postdoctoral Fellowship Program of CPSF(GZC20232098)as well as the Xiaomi Foundation through Xiaomi Young Scholar Program。
文摘The layer-by-layer deposition strategy of additive manufacturing makes it ideal to fabricate dissimilar alloy components with varying functionality,which has promising application potential in a large number of industrial areas.In this study,two components composed of ERCuAl-A2 aluminum bronze(CuAl9)and Inconel 718 nickel-based superalloy were fabricated with different deposition orders by wire-arc directed energy deposition.Subject to changes in heat input and thermophysical properties of the substrate,the transition region of the deposited Cu-Ni component with the bottom half of CuAl9 and the top half of Inconel 718 is narrow and serrated.This region features a laminated intermetallic compound layer due to the convection and rapid cooling in the molten pool.In contrast,the Ni-Cu component deposited in the opposite order exhibits a 2 mm gradient transition zone.Within this region,a large number of diverse precipitates were found as well as regional variations in grain size due to the multi-layer partial remelting.Both two components show strong bonds and their tensile specimens tested along the vertical direction always fracture at the softer CuAl9 side.Excellent tensile properties along the horizontal direction were obtained for Cu-Ni(Ultimate tensile strength:573 MPa,yield stress:302 MPa,elongation:22%),while those of Ni-Cu are much lower due to the existence of the solidification cracks in the transition zone.The results from this study provide a reference for the additive manufacturing of Cu/Ni dissimilar alloy components,as well as their microstructure and mechanical properties control.
基金supported by the National Natural Science Foundation of China(No.52275306)the Beijing Municipal Natural Science Foundation(No.3232021).
文摘The lamellar layer of intermetallic compounds(IMCs)was adversely affected the performance of welding-brazing joints in Al/steel dissimilar metals.In this study,a short fiber-like surface morphology was fabricated on the butt surface of Q235 steel via laser.The interaction behavior between the short fibers and the molten pool was captured using a high-speed camera.Laser-arc hybrid welding-brazing was then employed to join Al(6061-T6)to the steel.This process successfully created a short fiber-like interface structure at the joint.The relationship between microstructure and mechanical properties was investigated,compared with Al/bare steel(ABS)joint.The research results indicated that the IMCs layer consisted of FeAl_(3)and Fe_(2)Al_(5).The interface strength of the Al/short fiber-like surface structural steel(ASFSSS)joint reached 153.2 MPa,an 82.2%increase compared to the ABS joint,which reached 84.1 MPa.When the ASFSSS joints without the reinforcement were bent to 58.2°and 25.2°in the longitudinal and transverse direction,respectively,they remained intact.However,cracks were discovered when the bending angle of the ABS reached 39.1°and 0°in the two directions.Numerical simulation revealed that the short fiber-like interface structure significantly reduced residual stress and improved the stress distribution in the weld,thereby enhancing the strength and toughness of Al/steel dissimilar joints.The crack propagation path in the ASFSSS joint was deflected into the weld when it encountered short fibers,and the fracture morphology presented the characteristic of ductile-brittle mixed fracture.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52005240,52164045)Young Talent Program of Major Disciplines of Academic and Technical Leaders in Jiangxi Province(No.20212BCJ23028)Outstanding Youth Foundation in Jiangxi Province(No.20224ACB214012).
文摘Friction stir lap welding(FSLW)was adopted to join successfully dissimilar AZ31B Mg alloy and TC4 Ti alloy with Sn foil addition of 30μm thickness.Interfacial microstructure,tensile shear performances and bonding mechanism of the joints obtained using three different rotation speeds were studied.High-performance FSLW Mg/Ti dissimilar joints with maximum tensile shear strength of 593.3 N/mm were produced at 1180 r/min,and which was mainly attributed to ultrastrong reaction interlayer consisting of 125.9 nm thick(Mg_(2)Sn+Mg)transition layer and discontinuous(Ti_(6)Sn_(5)+Ti_(3)Al)IMCs layer with 6.58 nm thickness at the interface.The formation of the reaction interlayer was beneficial for high interfacial strength,resulting in significantly improving the joint strength.The fracture of all FSLW joints located on AZ31B Mg stirred zone adjacent to(Mg_(2)Sn+Mg)transition layer or along the crack propagation direction of the AZ31B/TC4 interface with different fracture mechanisms,and which could be consistent with interfacial microstructure.
基金the China Scholarship Council(No.201708510113)for fellowship and funding.
文摘Plasma electrolytic oxidation(PEO)processing of light metals has been established for decades and is in increasing industrial use,even as an alternative surface treatment to produce multifunctional coatings with environmental-friendly processing concept.One of the benefits of PEO processing claimed already a couple of years ago was the ability to treat dissimilar metal joints,which can obviously improve the surface homogeneity and stability at the interface of the dissimilar components,especially impeding the galvanic corrosion due to the different electrochemical properties of each component.However,the progress and breakthrough develop slowly especially for the macro scales due to the much larger gap between each component.This literature review firstly demonstrates the still low number of studies reporting successful PEO treatment of material combination such as Mg/Al,Mg/Ti,Al/Ti and scarcely light metal combinations with steel.The main issues and challenges to performing PEO processing on the macroscale dissimilar weldments were stated.On the other hand,dissimilar metal joints also widely exist in micrometer scale in alloys and metal matrix composites(MMCs).Moreover,there is a huge knowledge base on PEO treatment of such multiphase substrates.PEO processing of such complicated mixed microstructures is reviewed as well to reveal the basic problems.To some certain degree,these PEO-related studies on alloys and MMCs can be good examples to have an insight into the coating formation mechanism on macro-scaled dissimilar metal joints.Conclusions are drawn from the micro-to macroscale.Finally,critical access to the problems is given and possible solutions and reaming limitations are discussed.
基金The SEU Innovation Capability Enhancement Plan for Doctoral Students(No.CXJH_SEU 24115)Marine Economic Development Project of Guangdong Province(No.GDNRC[2022]25).
文摘The study aimed to address the issue of elevated residual stress levels in dissimilar girth welds of cast steel joints.To achieve this,the hybrid welding technology,which yields high welding speeds while simultaneously reducing residual stresses,has been introduced.This study utilizes a numerical simulation method to investigate the temperature and residual stress field in the hybrid welding of G20Mn5 casting-Q355 low-alloy steel welded pipe.A com-parison of the findings of this study with those of other welding processes revealed the technological advantages of hybrid welding.The research outcomes show that due to geometric discontinuities and material differences,the temperature field of the joint exhibits uneven distribution characteristics,and the peak temperatures on the Q355 steel side exceeds those on the G20Mn5 steel side.An evident stress gra-dient is present in the residual stress field of the joint post-welding,with peak stress located at the weld root on the Q355 steel.Compared with arc welding,the hybrid welding leads to decreased residual stresses and deformation,with high stress outside the heat-affected zone diminishing rapidly.Furthermore,it significantly improves the welding efficiency.This study elucidates the distribution and underlying causes of thermal and residual stress fields in dissimilar girth welds.This serves as a foundation for the application of hybrid welding technology in welded cast steel joints.
