In this paper, we propose a new online system that can quickly detect malicious spam emails and adapt to the changes in the email contents and the Uniform Resource Locator (URL) links leading to malicious websites by ...In this paper, we propose a new online system that can quickly detect malicious spam emails and adapt to the changes in the email contents and the Uniform Resource Locator (URL) links leading to malicious websites by updating the system daily. We introduce an autonomous function for a server to generate training examples, in which double-bounce emails are automatically collected and their class labels are given by a crawler-type software to analyze the website maliciousness called SPIKE. In general, since spammers use botnets to spread numerous malicious emails within a short time, such distributed spam emails often have the same or similar contents. Therefore, it is not necessary for all spam emails to be learned. To adapt to new malicious campaigns quickly, only new types of spam emails should be selected for learning and this can be realized by introducing an active learning scheme into a classifier model. For this purpose, we adopt Resource Allocating Network with Locality Sensitive Hashing (RAN-LSH) as a classifier model with a data selection function. In RAN-LSH, the same or similar spam emails that have already been learned are quickly searched for a hash table in Locally Sensitive Hashing (LSH), in which the matched similar emails located in “well-learned” are discarded without being used as training data. To analyze email contents, we adopt the Bag of Words (BoW) approach and generate feature vectors whose attributes are transformed based on the normalized term frequency-inverse document frequency (TF-IDF). We use a data set of double-bounce spam emails collected at National Institute of Information and Communications Technology (NICT) in Japan from March 1st, 2013 until May 10th, 2013 to evaluate the performance of the proposed system. The results confirm that the proposed spam email detection system has capability of detecting with high detection rate.展开更多
In recent years, the nearest neighbor search （NNS） problem has been widely used in various interesting applications. Locality-sensitive hashing （LSH）, a popular algorithm for the approximate nearest neighbor probl...In recent years, the nearest neighbor search （NNS） problem has been widely used in various interesting applications. Locality-sensitive hashing （LSH）, a popular algorithm for the approximate nearest neighbor problem, is proved to be an efficient method to solve the NNS problem in the high-dimensional and large-scale databases. Based on the scheme of p-stable LSH, this paper introduces a novel improvement algorithm called randomness-based locality-sensitive hashing （RLSH） based on p-stable LSH. Our proposed algorithm modifies the query strategy that it randomly selects a certain hash table to project the query point instead of mapping the query point into all hash tables in the period of the nearest neighbor query and reconstructs the candidate points for finding the nearest neighbors. This improvement strategy ensures that RLSH spends less time searching for the nearest neighbors than the p-stable LSH algorithm to keep a high recall. Besides, this strategy is proved to promote the diversity of the candidate points even with fewer hash tables. Experiments are executed on the synthetic dataset and open dataset. The results show that our method can cost less time consumption and less space requirements than the p-stable LSH while balancing the same recall.展开更多
BACKGROUND Neutrophil extracellular traps(NETs)are associated with an immunosuppressive tumor microenvironment and may influence the efficacy of immune-based therapies.However,their role in neoadjuvant chemotherapy co...BACKGROUND Neutrophil extracellular traps(NETs)are associated with an immunosuppressive tumor microenvironment and may influence the efficacy of immune-based therapies.However,their role in neoadjuvant chemotherapy combined with immunotherapy(NACI)for locally advanced gastric cancer(LAGC)remains unclear.AIM To investigate the prognostic and predictive value of NET density in LAGC patients undergoing NACI.METHODS We enrolled 31 LAGC patients treated with NACI.NET density was assessed through dual immunofluorescence staining of citrullinated histone H3 and myeloperoxidase in pretreatment biopsy and post-treatment surgical specimens.Patients were stratified into high and low pre-NACI NET groups based on median NET density.Pathological complete response(pCR)and overall response rates were evaluated in relation to NET density.Logistic regression analyses were performed to identify independent predictors of treatment outcomes.Dynamic changes in NET density during NACI were also analyzed.RESULTS Patients with low pre-NACI NET density demonstrated significantly higher rates of pCR(40%vs 6%,P=0.037)and overall response(53%vs 12%,P=0.023)compared to those with high NET density.Low pre-NACI NET density and higher programmed death protein ligand 1 expression were identified as independent protective factors for achieving pCR and better response rates.NACI increased NET density;however,this increase was primarily observed in non-pCR and nonresponder groups.Patients in the pCR and responder groups showed stable NET density before and after treatment.Higher post-NACI NET density was associated with poorer respond to NACI.High post-NACI NET density was associated with increased infiltration of immunosuppressive FOXP3+T regulatory cells(P=0.025)and CD68+macrophages(P=0.038).CONCLUSION Pre-NACI NET density serves as a prognostic and predictive biomarker for NACI efficacy in LAGC patients.Low pretreatment NET density is associated with favorable outcomes,while increased post-treatment NET density correlates with poorer response.Targeting NET formation may represent a novel therapeutic strategy to enhance NACI efficacy in LAGC.展开更多
The deformation localization in strain-rate sensitive porous materials is analyzed based on the lower bound approach proposed by the author. The retarding effect of material viscosity on deformation localization and t...The deformation localization in strain-rate sensitive porous materials is analyzed based on the lower bound approach proposed by the author. The retarding effect of material viscosity on deformation localization and the influence of the material strain-rate sensitivity factor on the critical strain to localized necking and the shear localization are investigated. Consideration concerning the material inhomogeneity and the void nucleation effect is also given. Finally the fracture strains of the plane strain tension specimens of AISI4340 steels are calculated and the results are compared with those of the experiment and of Gurson's equations.展开更多
In the field of rail transit,the UK Department of Transport stated that it will realize a comprehensive transformation of UK railways by 2050,abandoning traditional diesel trains and upgrading them to new environmenta...In the field of rail transit,the UK Department of Transport stated that it will realize a comprehensive transformation of UK railways by 2050,abandoning traditional diesel trains and upgrading them to new environmentally friendly trains.The current mainstream upgrade methods are electrification and hydrogen fuel cells.Comprehensive upgrades are costly,and choosing the optimal upgrade method for trams and mainline railways is critical.Without a sensitivity analysis,it is difficult for us to determine the influence relationship between each parameter and cost,resulting in a waste of cost when choosing a line reconstruction method.In addition,by analyzing the sensitivity of different parameters to the cost,the primary optimization direction can be determined to reduce the cost.Global higher-order sensitivity analysis enables quantification of parameter interactions,showing non-additive effects between parameters.This paper selects the main parameters that affect the retrofit cost and analyzes the retrofit cost of the two upgrade methods in the case of trams and mainline railways through local and global sensitivity analysis methods.The results of the analysis show that,given the current UK rail system,it is more economical to choose electric trams and hydrogen mainline trains.For trams,the speed at which the train travels has the greatest impact on the final cost.Through the sensitivity analysis,this paper provides an effective data reference for the current railway upgrading and reconstruction plan and provides a theoretical basis for the next step of train parameter optimization.展开更多
With the growing penetration of wind power in power systems, more accurate prediction of wind speed and wind power is required for real-time scheduling and operation. In this paper, a novel forecast model for shortter...With the growing penetration of wind power in power systems, more accurate prediction of wind speed and wind power is required for real-time scheduling and operation. In this paper, a novel forecast model for shortterm prediction of wind speed and wind power is proposed,which is based on singular spectrum analysis(SSA) and locality-sensitive hashing(LSH). To deal with the impact of high volatility of the original time series, SSA is applied to decompose it into two components: the mean trend,which represents the mean tendency of the original time series, and the fluctuation component, which reveals the stochastic characteristics. Both components are reconstructed in a phase space to obtain mean trend segments and fluctuation component segments. After that, LSH is utilized to select similar segments of the mean trend segments, which are then employed in local forecasting, so that the accuracy and efficiency of prediction can be enhanced. Finally, support vector regression is adopted forprediction, where the training input is the synthesis of the similar mean trend segments and the corresponding fluctuation component segments. Simulation studies are conducted on wind speed and wind power time series from four databases, and the final results demonstrate that the proposed model is more accurate and stable in comparison with other models.展开更多
Many multi-story or highrise buildings consisting of a number of identical stories are usually considered as periodic spring-mass systems. The general expressions of natural frequencies, mode shapes, slopes and curvat...Many multi-story or highrise buildings consisting of a number of identical stories are usually considered as periodic spring-mass systems. The general expressions of natural frequencies, mode shapes, slopes and curvatures of mode shapes of the periodic spring-mass system by utilizing the periodic structure theory are derived in this paper. The sensitivities of these mode parameters with respect to structural damages, which do not depend on the physical parameters of the original structures, are obtained. Based on the sensitivity analysis of these mode parameters, a two-stage method is proposed to localize and quantify damages of multi-story or highrise buildings. The slopes and curvatures of mode shapes, which are highly sensitive to local damages, are used to localize the damages. Subsequently, the limited measured natural frequencies, which have a better accuracy than the other mode parameters, are used to quantify the extent of damages within the potential damaged locations. The experimental results of a 3-story experimental building demonstrate that the single or multiple damages of buildings, either slight or severe, can be correctly localized by using only the slope or curvature of mode shape in one of the lower modes, in which the change of natural frequency is the largest, and can be accurately quantified by the limited measured natural frequencies with noise pollution.展开更多
Highly homogeneous, well dispersed SiO_2@Au@TiO_2(SAT) microspheres decorated with Au nanoparticles(AuNPs) were prepared and incorporated into the photoanode with an optimized concentration gradientascent. The effects...Highly homogeneous, well dispersed SiO_2@Au@TiO_2(SAT) microspheres decorated with Au nanoparticles(AuNPs) were prepared and incorporated into the photoanode with an optimized concentration gradientascent. The effects of SAT microspheres and the gradient-ascent architecture on the light absorption and the photoelectric conversion efficiency(PCE) of the dye-sensitized solar cells(DSSCs) were investigated.Studies indicate that the introduction of SAT microspheres and the gradient-ascent architecture in the photoanode significantly enhance the light scattering and harvesting capability of the photoanode. The DSSC with the optimized SAT gradient-ascent photoanode has the maximum short circuit current density(J_(sc)) of 17.7 mA cm^(-2) and PCE of 7.75%, remarkably higher than those of the conventional DSSC by 23.7%and 28.0%, respectively. This significantly enhancement of the performance of the DSSC can be attributed to the excellent light reflection/scattering of SAT, the localized surface plasma resonance(LSPR) effect of AuNPs within the microspheres, and the gradient-ascent architecture of SAT microspheres inside the photoanode. This study demonstrates that the tri-synergies of the scattering of SAT microspheres, the LSPR of AuNPs and the gradient-ascent architecture can effectively improve the PCE of DSSC.展开更多
Lightweight design has a significant impact on reducing fuel consumption and harmful emission of conventional vehicles and improving driving range of electric vehicles. Reducing the thickness of components in vehicle ...Lightweight design has a significant impact on reducing fuel consumption and harmful emission of conventional vehicles and improving driving range of electric vehicles. Reducing the thickness of components in vehicle bodies and closures is an efficient approach for weight reduction. Thickness reduction, however, will reduce structural stiffness, especially in the presence of lateral displacements of buckling when critical stress is reached. In this paper, nonlinear FEA models of a thin-walled beam with variable thickness are developed for calculating the changes of beam stiffness as to thickness reduction in the pre- and post-buckling stages. Next, these stiffness values are used to calculate gauge sensitivity of the beam, which changes with respect to beam thickness changes. It is concluded that the presence of buckling will reduce the beam stiffness, worsen the stress uniformity, and increase the gauge sensitivity value of the beam.展开更多
文摘In this paper, we propose a new online system that can quickly detect malicious spam emails and adapt to the changes in the email contents and the Uniform Resource Locator (URL) links leading to malicious websites by updating the system daily. We introduce an autonomous function for a server to generate training examples, in which double-bounce emails are automatically collected and their class labels are given by a crawler-type software to analyze the website maliciousness called SPIKE. In general, since spammers use botnets to spread numerous malicious emails within a short time, such distributed spam emails often have the same or similar contents. Therefore, it is not necessary for all spam emails to be learned. To adapt to new malicious campaigns quickly, only new types of spam emails should be selected for learning and this can be realized by introducing an active learning scheme into a classifier model. For this purpose, we adopt Resource Allocating Network with Locality Sensitive Hashing (RAN-LSH) as a classifier model with a data selection function. In RAN-LSH, the same or similar spam emails that have already been learned are quickly searched for a hash table in Locally Sensitive Hashing (LSH), in which the matched similar emails located in “well-learned” are discarded without being used as training data. To analyze email contents, we adopt the Bag of Words (BoW) approach and generate feature vectors whose attributes are transformed based on the normalized term frequency-inverse document frequency (TF-IDF). We use a data set of double-bounce spam emails collected at National Institute of Information and Communications Technology (NICT) in Japan from March 1st, 2013 until May 10th, 2013 to evaluate the performance of the proposed system. The results confirm that the proposed spam email detection system has capability of detecting with high detection rate.
基金Project supported by the National Natural Science Foundation of China(Grant No.61173143)the Special Public Sector Research Program of China(Grant No.GYHY201206030)the Deanship of Scientific Research at King Saud University for funding this work through research group No.RGP-VPP-264
文摘In recent years, the nearest neighbor search （NNS） problem has been widely used in various interesting applications. Locality-sensitive hashing （LSH）, a popular algorithm for the approximate nearest neighbor problem, is proved to be an efficient method to solve the NNS problem in the high-dimensional and large-scale databases. Based on the scheme of p-stable LSH, this paper introduces a novel improvement algorithm called randomness-based locality-sensitive hashing （RLSH） based on p-stable LSH. Our proposed algorithm modifies the query strategy that it randomly selects a certain hash table to project the query point instead of mapping the query point into all hash tables in the period of the nearest neighbor query and reconstructs the candidate points for finding the nearest neighbors. This improvement strategy ensures that RLSH spends less time searching for the nearest neighbors than the p-stable LSH algorithm to keep a high recall. Besides, this strategy is proved to promote the diversity of the candidate points even with fewer hash tables. Experiments are executed on the synthetic dataset and open dataset. The results show that our method can cost less time consumption and less space requirements than the p-stable LSH while balancing the same recall.
文摘BACKGROUND Neutrophil extracellular traps(NETs)are associated with an immunosuppressive tumor microenvironment and may influence the efficacy of immune-based therapies.However,their role in neoadjuvant chemotherapy combined with immunotherapy(NACI)for locally advanced gastric cancer(LAGC)remains unclear.AIM To investigate the prognostic and predictive value of NET density in LAGC patients undergoing NACI.METHODS We enrolled 31 LAGC patients treated with NACI.NET density was assessed through dual immunofluorescence staining of citrullinated histone H3 and myeloperoxidase in pretreatment biopsy and post-treatment surgical specimens.Patients were stratified into high and low pre-NACI NET groups based on median NET density.Pathological complete response(pCR)and overall response rates were evaluated in relation to NET density.Logistic regression analyses were performed to identify independent predictors of treatment outcomes.Dynamic changes in NET density during NACI were also analyzed.RESULTS Patients with low pre-NACI NET density demonstrated significantly higher rates of pCR(40%vs 6%,P=0.037)and overall response(53%vs 12%,P=0.023)compared to those with high NET density.Low pre-NACI NET density and higher programmed death protein ligand 1 expression were identified as independent protective factors for achieving pCR and better response rates.NACI increased NET density;however,this increase was primarily observed in non-pCR and nonresponder groups.Patients in the pCR and responder groups showed stable NET density before and after treatment.Higher post-NACI NET density was associated with poorer respond to NACI.High post-NACI NET density was associated with increased infiltration of immunosuppressive FOXP3+T regulatory cells(P=0.025)and CD68+macrophages(P=0.038).CONCLUSION Pre-NACI NET density serves as a prognostic and predictive biomarker for NACI efficacy in LAGC patients.Low pretreatment NET density is associated with favorable outcomes,while increased post-treatment NET density correlates with poorer response.Targeting NET formation may represent a novel therapeutic strategy to enhance NACI efficacy in LAGC.
文摘The deformation localization in strain-rate sensitive porous materials is analyzed based on the lower bound approach proposed by the author. The retarding effect of material viscosity on deformation localization and the influence of the material strain-rate sensitivity factor on the critical strain to localized necking and the shear localization are investigated. Consideration concerning the material inhomogeneity and the void nucleation effect is also given. Finally the fracture strains of the plane strain tension specimens of AISI4340 steels are calculated and the results are compared with those of the experiment and of Gurson's equations.
文摘In the field of rail transit,the UK Department of Transport stated that it will realize a comprehensive transformation of UK railways by 2050,abandoning traditional diesel trains and upgrading them to new environmentally friendly trains.The current mainstream upgrade methods are electrification and hydrogen fuel cells.Comprehensive upgrades are costly,and choosing the optimal upgrade method for trams and mainline railways is critical.Without a sensitivity analysis,it is difficult for us to determine the influence relationship between each parameter and cost,resulting in a waste of cost when choosing a line reconstruction method.In addition,by analyzing the sensitivity of different parameters to the cost,the primary optimization direction can be determined to reduce the cost.Global higher-order sensitivity analysis enables quantification of parameter interactions,showing non-additive effects between parameters.This paper selects the main parameters that affect the retrofit cost and analyzes the retrofit cost of the two upgrade methods in the case of trams and mainline railways through local and global sensitivity analysis methods.The results of the analysis show that,given the current UK rail system,it is more economical to choose electric trams and hydrogen mainline trains.For trams,the speed at which the train travels has the greatest impact on the final cost.Through the sensitivity analysis,this paper provides an effective data reference for the current railway upgrading and reconstruction plan and provides a theoretical basis for the next step of train parameter optimization.
基金supported by the Guangdong Innovative Research Team Program(No.201001N0104744201)the State Key Program of the National Natural Science Foundation of China(No.51437006)
文摘With the growing penetration of wind power in power systems, more accurate prediction of wind speed and wind power is required for real-time scheduling and operation. In this paper, a novel forecast model for shortterm prediction of wind speed and wind power is proposed,which is based on singular spectrum analysis(SSA) and locality-sensitive hashing(LSH). To deal with the impact of high volatility of the original time series, SSA is applied to decompose it into two components: the mean trend,which represents the mean tendency of the original time series, and the fluctuation component, which reveals the stochastic characteristics. Both components are reconstructed in a phase space to obtain mean trend segments and fluctuation component segments. After that, LSH is utilized to select similar segments of the mean trend segments, which are then employed in local forecasting, so that the accuracy and efficiency of prediction can be enhanced. Finally, support vector regression is adopted forprediction, where the training input is the synthesis of the similar mean trend segments and the corresponding fluctuation component segments. Simulation studies are conducted on wind speed and wind power time series from four databases, and the final results demonstrate that the proposed model is more accurate and stable in comparison with other models.
基金Project supported by the National Natural Science Foundation of China (No. 50378041) Specialized Research Fund for Doctoral Programs of Higher Education (No. 20030487016).
文摘Many multi-story or highrise buildings consisting of a number of identical stories are usually considered as periodic spring-mass systems. The general expressions of natural frequencies, mode shapes, slopes and curvatures of mode shapes of the periodic spring-mass system by utilizing the periodic structure theory are derived in this paper. The sensitivities of these mode parameters with respect to structural damages, which do not depend on the physical parameters of the original structures, are obtained. Based on the sensitivity analysis of these mode parameters, a two-stage method is proposed to localize and quantify damages of multi-story or highrise buildings. The slopes and curvatures of mode shapes, which are highly sensitive to local damages, are used to localize the damages. Subsequently, the limited measured natural frequencies, which have a better accuracy than the other mode parameters, are used to quantify the extent of damages within the potential damaged locations. The experimental results of a 3-story experimental building demonstrate that the single or multiple damages of buildings, either slight or severe, can be correctly localized by using only the slope or curvature of mode shape in one of the lower modes, in which the change of natural frequency is the largest, and can be accurately quantified by the limited measured natural frequencies with noise pollution.
基金supported financially by the National Natural Science Foundation of China (Nos.51572102,11504101,11604089 and 11364018)
文摘Highly homogeneous, well dispersed SiO_2@Au@TiO_2(SAT) microspheres decorated with Au nanoparticles(AuNPs) were prepared and incorporated into the photoanode with an optimized concentration gradientascent. The effects of SAT microspheres and the gradient-ascent architecture on the light absorption and the photoelectric conversion efficiency(PCE) of the dye-sensitized solar cells(DSSCs) were investigated.Studies indicate that the introduction of SAT microspheres and the gradient-ascent architecture in the photoanode significantly enhance the light scattering and harvesting capability of the photoanode. The DSSC with the optimized SAT gradient-ascent photoanode has the maximum short circuit current density(J_(sc)) of 17.7 mA cm^(-2) and PCE of 7.75%, remarkably higher than those of the conventional DSSC by 23.7%and 28.0%, respectively. This significantly enhancement of the performance of the DSSC can be attributed to the excellent light reflection/scattering of SAT, the localized surface plasma resonance(LSPR) effect of AuNPs within the microspheres, and the gradient-ascent architecture of SAT microspheres inside the photoanode. This study demonstrates that the tri-synergies of the scattering of SAT microspheres, the LSPR of AuNPs and the gradient-ascent architecture can effectively improve the PCE of DSSC.
文摘Lightweight design has a significant impact on reducing fuel consumption and harmful emission of conventional vehicles and improving driving range of electric vehicles. Reducing the thickness of components in vehicle bodies and closures is an efficient approach for weight reduction. Thickness reduction, however, will reduce structural stiffness, especially in the presence of lateral displacements of buckling when critical stress is reached. In this paper, nonlinear FEA models of a thin-walled beam with variable thickness are developed for calculating the changes of beam stiffness as to thickness reduction in the pre- and post-buckling stages. Next, these stiffness values are used to calculate gauge sensitivity of the beam, which changes with respect to beam thickness changes. It is concluded that the presence of buckling will reduce the beam stiffness, worsen the stress uniformity, and increase the gauge sensitivity value of the beam.
