Geolocating social media users aims to discover the real geographical locations of users from their publicly available data,which can support online location-based applications such as disaster alerts and local conten...Geolocating social media users aims to discover the real geographical locations of users from their publicly available data,which can support online location-based applications such as disaster alerts and local content recommen-dations.Social relationship-based methods represent a classical approach for geolocating social media.However,geographically proximate relationships are sparse and challenging to discern within social networks,thereby affecting the accuracy of user geolocation.To address this challenge,we propose user geolocation methods that integrate neighborhood geographical distribution and social structure influence(NGSI)to improve geolocation accuracy.Firstly,we propose a method for evaluating the homophily of locations based on the k-order neighbor-hood geographic distribution(k-NGD)similarity among users.There are notable differences in the distribution of k-NGD similarity between location-proximate and non-location-proximate users.Exploiting this distinction,we filter out non-location-proximate social relationships to enhance location homophily in the social network.To better utilize the location-proximate relationships in social networks,we propose a graph neural network algorithm based on the social structure influence.The algorithm enables us to perform a weighted aggregation of the information of users’multi-hop neighborhood,thereby mitigating the over-smoothing problem of user features and improving user geolocation performance.Experimental results on real social media dataset demonstrate that the neighborhood geographical distribution similarity metric can effectively filter out non-location-proximate social relationships.Moreover,compared with 7 existing social relationship-based user positioning methods,our proposed method can achieve multi-granularity user geolocation and improve the accuracy by 4.84%to 13.28%.展开更多
This paper deals with the characteristics of silicon modification with lanthanum of Al-Si eutectic alloy in sand mold and metal mold with optical microscopy,scanning electron microscopy,electron microprobe and X-ray d...This paper deals with the characteristics of silicon modification with lanthanum of Al-Si eutectic alloy in sand mold and metal mold with optical microscopy,scanning electron microscopy,electron microprobe and X-ray diffractometer.It is found that the amount of lanthanum,liquid alloy condition,holding time and stir- ring liquid influence the modification of silicon.The modification of silicon with lanthanum is of long effectiveness and has a“incubation time”.The modification can improve the ductility(δ_s)and tensile strength (σ_b)of the alloy,but their maximum values are not corresponding to the same amount of lanthanum.展开更多
In this work,the influence of heat treatment on Polyamide-1010 structure of aggregation state was studied by using WAXD and SAXS techniques.The results showed that the best crystallinity was obtained nearby T=175℃ fo...In this work,the influence of heat treatment on Polyamide-1010 structure of aggregation state was studied by using WAXD and SAXS techniques.The results showed that the best crystallinity was obtained nearby T=175℃ for Polyamide-1010 samples with various annealing treatment.Through extrapolating method,the Tg obtained was approximately 58℃.Based on the one-dimensional electron density correlation function of partially crystalline polymers,some structural parameters of Polyamide-1010 were determined by SAXS.展开更多
The microwave radiation method was introduced to prepare the Fe_2O_3/SO solid superacid.Its structure and properties were investigated by means of X-ray diffraction and infrared spectrum analyses as well as measuremen...The microwave radiation method was introduced to prepare the Fe_2O_3/SO solid superacid.Its structure and properties were investigated by means of X-ray diffraction and infrared spectrum analyses as well as measurement of magnetic susceptibility and rate of esterification. The structure of the superacids prepared in microwave field can be crystalline or non-crystalline, the latter has not been reported yet in literatures. Comparing with the traditional superacid, the non-crystalline Fe2O3/SO superacid prepared in microwave field has the highest magnetic susceptibility and catalytic activity. The di-coordination of Fe2O3 and SO and the S=O bi-bond were reinforced by microwave radiation, which is favorable for increasing the acid intensity of the Fe2O3/SO catalyst展开更多
Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into acc...Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into account the structural changes through the dislocation accumulation and annihilation process during deformation. The dislocation accumulation and annihilation factors show a temperature and structure dependence. The dislocation annihilation factor shows a plateau or decreasing tendency in the dynamic strain ageing (DSA) temperature range. This is attributed as either due to dislocation accumulation being more pronounced than dislocation annihilation or as due to precipitates being formed at DSA temperatures acting as obstacles to dislocation motion in the DSA temperature range.展开更多
In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspe...In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspect is the ground motions, which are usually assigned by engineers as a type of input load for seismic design of structures, sometimes can control the final design results. The experiments, performance evaluations and other related aspects are all based on the specified type of load. As a result, many aspects related to civil engineering will be influenced by changes of the type of load, Hence, the characteristics of the load and the corresponding response of structures are desired for studying. In this paper, the state-of-the-art of near-field problems in civil engineering is comprehensively reviewed, which include inherent characteristics of near-field ground motions and influences of these ground motions on civil structures. The existing problems are pointed out and work needed to be further investigated in the future is suggested. It is believed that the information in this paper can be useful to advance the state of investigation on near-field problems.展开更多
Heart function and plasma atrial natriuretic peptide (ANP).plasma renin actiity(PRA) andangiotensionⅡ(Ang Ⅱ) were examined with echocardiography and radioimmunoassay in patients with dilated cardiomyopathy(DCM),
Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete(RC) structure, especially when the concrete is in a saturated state. However, the single mechanism of di...Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete(RC) structure, especially when the concrete is in a saturated state. However, the single mechanism of diffusion is not able to describe the actual chloride ingress in the nonsaturated concrete. Instead, it is dominated by the interaction of diffusion and convection. With the synergetic effects of various factors taken into account, this study aimed to modify and develop an analytical convection- diffusion coupling model for chloride transport in nonsaturated concrete. The model was verified by simulation of laboratory tests and field measurement. The results of comparison study demonstrate that the analytical model developed in this study is efficient and accurate in predicting the chloride profiles in the nonsaturated concrete.展开更多
Failure mechanism and impact resistance of a human porous cranium are studied in detail by means of theoretical and numerical methods.It is hypothesized that pore distribution of a cranium directly affects cranial ene...Failure mechanism and impact resistance of a human porous cranium are studied in detail by means of theoretical and numerical methods.It is hypothesized that pore distribution of a cranium directly affects cranial energy absorption,and a stretched beam model and a real beam model are taken as the example for the verification.Meanwhile,for the purpose of comparison with numerical results,a theoretical model is also proposed for the prediction of residual velocity and contact force of the impactor for an impacted skull.Compared with the real beam model,the stretched beam model containing through-thickness pores is easily deformed under the impact,thereby buffering well the external impact energy.The energy absorption efficiency of both the stretched beam model and real beam model is concerned with the threshold velocity for penetration which is directly related to the size of the structural damage area.Overall,there is good agreement between numerical and theoretical results.In addition,the effect of structural geometric parameters(shape and size of the impactor)on the impact resistance of the skull bone is theoretically investigated.The study provides reference for the evaluation of the energy absorption and failure mechanism of the skull under impact loads.展开更多
基金This work was supported by the National Key R&D Program of China(No.2022YFB3102904)the National Natural Science Foundation of China(No.62172435,U23A20305)Key Research and Development Project of Henan Province(No.221111321200).
文摘Geolocating social media users aims to discover the real geographical locations of users from their publicly available data,which can support online location-based applications such as disaster alerts and local content recommen-dations.Social relationship-based methods represent a classical approach for geolocating social media.However,geographically proximate relationships are sparse and challenging to discern within social networks,thereby affecting the accuracy of user geolocation.To address this challenge,we propose user geolocation methods that integrate neighborhood geographical distribution and social structure influence(NGSI)to improve geolocation accuracy.Firstly,we propose a method for evaluating the homophily of locations based on the k-order neighbor-hood geographic distribution(k-NGD)similarity among users.There are notable differences in the distribution of k-NGD similarity between location-proximate and non-location-proximate users.Exploiting this distinction,we filter out non-location-proximate social relationships to enhance location homophily in the social network.To better utilize the location-proximate relationships in social networks,we propose a graph neural network algorithm based on the social structure influence.The algorithm enables us to perform a weighted aggregation of the information of users’multi-hop neighborhood,thereby mitigating the over-smoothing problem of user features and improving user geolocation performance.Experimental results on real social media dataset demonstrate that the neighborhood geographical distribution similarity metric can effectively filter out non-location-proximate social relationships.Moreover,compared with 7 existing social relationship-based user positioning methods,our proposed method can achieve multi-granularity user geolocation and improve the accuracy by 4.84%to 13.28%.
文摘This paper deals with the characteristics of silicon modification with lanthanum of Al-Si eutectic alloy in sand mold and metal mold with optical microscopy,scanning electron microscopy,electron microprobe and X-ray diffractometer.It is found that the amount of lanthanum,liquid alloy condition,holding time and stir- ring liquid influence the modification of silicon.The modification of silicon with lanthanum is of long effectiveness and has a“incubation time”.The modification can improve the ductility(δ_s)and tensile strength (σ_b)of the alloy,but their maximum values are not corresponding to the same amount of lanthanum.
文摘In this work,the influence of heat treatment on Polyamide-1010 structure of aggregation state was studied by using WAXD and SAXS techniques.The results showed that the best crystallinity was obtained nearby T=175℃ for Polyamide-1010 samples with various annealing treatment.Through extrapolating method,the Tg obtained was approximately 58℃.Based on the one-dimensional electron density correlation function of partially crystalline polymers,some structural parameters of Polyamide-1010 were determined by SAXS.
文摘The microwave radiation method was introduced to prepare the Fe_2O_3/SO solid superacid.Its structure and properties were investigated by means of X-ray diffraction and infrared spectrum analyses as well as measurement of magnetic susceptibility and rate of esterification. The structure of the superacids prepared in microwave field can be crystalline or non-crystalline, the latter has not been reported yet in literatures. Comparing with the traditional superacid, the non-crystalline Fe2O3/SO superacid prepared in microwave field has the highest magnetic susceptibility and catalytic activity. The di-coordination of Fe2O3 and SO and the S=O bi-bond were reinforced by microwave radiation, which is favorable for increasing the acid intensity of the Fe2O3/SO catalyst
文摘Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into account the structural changes through the dislocation accumulation and annihilation process during deformation. The dislocation accumulation and annihilation factors show a temperature and structure dependence. The dislocation annihilation factor shows a plateau or decreasing tendency in the dynamic strain ageing (DSA) temperature range. This is attributed as either due to dislocation accumulation being more pronounced than dislocation annihilation or as due to precipitates being formed at DSA temperatures acting as obstacles to dislocation motion in the DSA temperature range.
基金National Natural Science Foundation of China (50538050, 50608024)
文摘In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspect is the ground motions, which are usually assigned by engineers as a type of input load for seismic design of structures, sometimes can control the final design results. The experiments, performance evaluations and other related aspects are all based on the specified type of load. As a result, many aspects related to civil engineering will be influenced by changes of the type of load, Hence, the characteristics of the load and the corresponding response of structures are desired for studying. In this paper, the state-of-the-art of near-field problems in civil engineering is comprehensively reviewed, which include inherent characteristics of near-field ground motions and influences of these ground motions on civil structures. The existing problems are pointed out and work needed to be further investigated in the future is suggested. It is believed that the information in this paper can be useful to advance the state of investigation on near-field problems.
文摘Heart function and plasma atrial natriuretic peptide (ANP).plasma renin actiity(PRA) andangiotensionⅡ(Ang Ⅱ) were examined with echocardiography and radioimmunoassay in patients with dilated cardiomyopathy(DCM),
基金Funded by the National Natural Science Foundation of China(Nos.51278304,U1134209,U1434204&51422814)the National Basic Research Program(973 Program)of China(No.011-CB013604)the Technology Research and Development Program(Basic Research Project)of Shenzhen(Nos.JCYJ20120613174456685&JCYJ20130329143859418)
文摘Diffusion has been systematically described as the main mechanism of chloride transport in reinforced concrete(RC) structure, especially when the concrete is in a saturated state. However, the single mechanism of diffusion is not able to describe the actual chloride ingress in the nonsaturated concrete. Instead, it is dominated by the interaction of diffusion and convection. With the synergetic effects of various factors taken into account, this study aimed to modify and develop an analytical convection- diffusion coupling model for chloride transport in nonsaturated concrete. The model was verified by simulation of laboratory tests and field measurement. The results of comparison study demonstrate that the analytical model developed in this study is efficient and accurate in predicting the chloride profiles in the nonsaturated concrete.
基金This study was funded in part by the National Natural Science Foundation of China(Grant 12002107)the National Postdoctoral Program for Innovative Talents(Grant BX20190101)+3 种基金the China Postdoctoral Science Foundation(Grant 2019M661268)the Heilongjiang Postdoctoral Financial Assistance(Grant LBH-Z19061)The present work was also supported in part by Alexander von Humboldt Foundation(Grant 1155520)(University of Siegen,Germany)the Science and Technology on Advanced Composites in Special Environment Laboratory,Young Elite Scientist Sponsorship Program by CAST(Grant YESS20160190).
文摘Failure mechanism and impact resistance of a human porous cranium are studied in detail by means of theoretical and numerical methods.It is hypothesized that pore distribution of a cranium directly affects cranial energy absorption,and a stretched beam model and a real beam model are taken as the example for the verification.Meanwhile,for the purpose of comparison with numerical results,a theoretical model is also proposed for the prediction of residual velocity and contact force of the impactor for an impacted skull.Compared with the real beam model,the stretched beam model containing through-thickness pores is easily deformed under the impact,thereby buffering well the external impact energy.The energy absorption efficiency of both the stretched beam model and real beam model is concerned with the threshold velocity for penetration which is directly related to the size of the structural damage area.Overall,there is good agreement between numerical and theoretical results.In addition,the effect of structural geometric parameters(shape and size of the impactor)on the impact resistance of the skull bone is theoretically investigated.The study provides reference for the evaluation of the energy absorption and failure mechanism of the skull under impact loads.