The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays a...The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays an important role in the central nervous system, where it is associated with glutamatergic signaling, and it is widely involved in inflammatory processes. Thus, diseases involving copper(Ⅱ) dyshomeostasis often have neurological symptoms, as exemplified by Alzheimer's and other diseases(such as Parkinson's and Wilson's diseases). Moreover, imbalanced copper ion concentrations have also been associated with diabetes and certain types of cancer, including glioma. In this paper, we propose a comprehensive overview of recent results that show the importance of these metal ions in several pathologies, mainly Alzheimer's disease, through the lens of the development and use of copper chelators as research compounds and potential therapeutics if included in multi-target hybrid drugs. Seeing how copper homeostasis is important for the well-being of animals as well as humans, we shortly describe the state of the art regarding the effects of copper and its chelators in agriculture, livestock rearing, and aquaculture, as ingredients for the formulation of feed supplements as well as to prevent the effects of pollution on animal productions.展开更多
Purpose:This study investigates whether publication-centric incentive systems,introduced through the National Scientific Accreditation(ASN:Abilitazione Scientifica Nazionale)for professorships in Italy in 2012,contrib...Purpose:This study investigates whether publication-centric incentive systems,introduced through the National Scientific Accreditation(ASN:Abilitazione Scientifica Nazionale)for professorships in Italy in 2012,contribute to adopting“salami publishing”strategies among Italian academics.Design/methodology/approach:A longitudinal bibliometric analysis was conducted on the publication records of over 25,000 Italian science professors to examine changes in publication output and the originality of their work following the implementation of the ASN.Findings:The analysis revealed a significant increase in publication output after the ASN’s introduction,along with a concurrent decline in the originality of publications.However,no evidence was found linking these trends to increased salami slicing practices among the observed researchers.Research limitations:Given the size of our observation field,we propose an innovative indirect approach based on the degree of originality of publications’bibliographies.We know that bibliographic coupling cannot capture salami publications per se,but only topically-related records.On the other hand,controlling for the author’s specialization level in the period,we believe that a higher level of bibliographic coupling in his scientific output can signal a change in his strategy of disseminating the results of his research.The relatively low R-squared values in our models(0.3-0.4)reflect the complexity of the phenomenon under investigation,revealing the presence of unmeasured factors influencing the outcomes,and future research should explore additional variables or alternative models that might account for a greater proportion of the variability.Despite this limitation,the significant predictors identified in our analysis provide valuable insights into the key factors driving the observed outcomes.Practical implications:The results of the study support those who argue that quantitative research assessment frameworks have had very positive effects and should not be dismissed,contrary to the claims of those evoking the occurrence of side effects that do not appear in the empirical analyses.Originality/value:This study provides empirical evidence on the impact of the ASN on publication behaviors in a huge micro-level dataset,contributing to the broader discourse on the effects of quantitative research assessments on academic publishing practices.展开更多
This study presents an innovative approach to calculating the failure probability of slopes by incorporating fuzzylimit-state functions,a method that significantly enhances the accuracy and efficiency of slope stabili...This study presents an innovative approach to calculating the failure probability of slopes by incorporating fuzzylimit-state functions,a method that significantly enhances the accuracy and efficiency of slope stability analysis.Unlike traditional probabilistic techniques,this approach utilizes a least squares support vector machine(LSSVM)optimized with a grey wolf optimizer(GWO)and K-fold cross-validation(CV)to approximate the limit-statefunction,thus reducing computational complexity.The novelty of this work lies in its application to one-dimensional(1D),two-dimensional(2D),and three-dimensional(3D)slope models,demonstrating its versatility andhigh precision.The proposed method consistently achieves error margins within 3%of Monte Carlo simulation(MCS)results,while substantially reducing computation time,particularly for 2D and 3D models.This makes theapproach highly practical for real-world engineering applications.Furthermore,by applying fuzzy mathematics tohandle uncertainties in geotechnical properties,the method offers a more realistic and comprehensive understandingof slope stability.As water is the main factor influencing the stability of slopes,this aspect is investigatedby calculating the phreatic line after the change in water level.Relevant examples are used to show that the failureprobability of a slope under water wading condition can increase by more than 20%(increase rates in 1D,2D and3D conditions being 25%,27%and 31%,respectively)compared with the natural condition.The influence ofdiverse fuzzy membership functions—linear,normal,and Cauchy—on failure probability is also considered.Thisresearch not only provides a strategy for better calculation of the slope failure probability but also pioneers theintegration of computational intelligence,fuzzy logic and fluid-dynamics in geotechnical engineering,presentingan innovative and efficient tool for slope stability analysis.展开更多
Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the s...Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.展开更多
Purpose:Scholars face an unprecedented ever increasing demand for acting as reviewers for journals,recruitment and promotion committees,granting agencies,and research assessment agencies.Consequently,journal editors f...Purpose:Scholars face an unprecedented ever increasing demand for acting as reviewers for journals,recruitment and promotion committees,granting agencies,and research assessment agencies.Consequently,journal editors face an ever increasing scarcity of experts willing to act as reviewers.It is not infrequent that reviews diverge,which forces editors to recur to additional reviewers or make a final decision on their own.The purpose of the proposed bibliometric system is to support of editors’accept/reject decisions in such situations.Design/methodology/approach:We analyse nearly two million 2017 publications and their scholarly impact,measured by normalized citations.Based on theory and previous literature,we extrapolated the publication traits of text,byline,and bibliographic references expected to be associated with future citations.We then fitted a regression model with the outcome variable as the scholarly impact of the publication and the independent variables as the above non-scientific traits,controlling for fixed effects at the journal level.Findings:Non-scientific factors explained more than 26%of the paper’s impact,with slight variation across disciplines.On average,OA articles have a 7%greater impact than non-OA articles.A 1%increase in the number of references was associated with an average increase of 0.27%in impact.Higher-impact articles in the reference list,the number of authors and of countries in the byline,the article length,and the average impact of co-authors’past publications all show a positive association with the article’s impact.Female authors,authors from English-speaking countries,and the average age of the article’s references show instead a negative association.Research limitations:The selected non-scientific factors are the only observable and measurable ones to us,but we cannot rule out the presence of significant omitted variables.Using citations as a measure of impact has well-known limitations and overlooks other forms of scholarly influence.Additionally,the large dataset constrained us to one year’s global publications,preventing us from capturing and accounting for time effects.Practical implications:This study provides journal editors with a quantitative model that complements peer reviews,particularly when reviewer evaluations diverge.By incorporating non-scientific factors that significantly predict a paper’s future impact,editors can make more informed decisions,reduce reliance on additional reviewers,and improve the efficiency and fairness of the manuscript selection process.Originality/value:To the best of our knowledge,this study is the first one to specifically address the problem of supporting editors in any field in their decisions on submitted manuscripts with a quantitative model.Previous works have generally investigated the relationship between a few of the above publication traits and their impact or the agreement between peer-review and bibliometric evaluations of publications.展开更多
For the purpose of realizing the information visualization of hydropower engineering management, we construeted three kinds of graphics models sorted by hierarchy for system modelling, employed the construction simula...For the purpose of realizing the information visualization of hydropower engineering management, we construeted three kinds of graphics models sorted by hierarchy for system modelling, employed the construction simulation system to simulate the real-time construction behaviours, introduced the graphics rendering system to organize and update the virtual scene, and designed the interaction system to respond to the user-initiated and simulation-initiated events. So, the real-time, interactive visualization aided system of hydropower engineering management is developed. Eventually, the effectiveness and capabilities of the system are showed through the application examples in China.展开更多
In recent years,frequent fire disasters have led to enormous damage in China.Effective firefighting rescues can minimize the losses caused by fires.During the rescue processes,the travel time of fire trucks can be sev...In recent years,frequent fire disasters have led to enormous damage in China.Effective firefighting rescues can minimize the losses caused by fires.During the rescue processes,the travel time of fire trucks can be severely affected by traffic conditions,changing the effective coverage of fire stations.However,it is still challenging to determine the effective coverage of fire stations considering dynamic traffic conditions.This paper addresses this issue by combining the traveling time calculationmodelwith the effective coverage simulationmodel.In addition,it proposes a new index of total effective coverage area(TECA)based on the time-weighted average of the effective coverage area(ECA)to evaluate the urban fire services.It also selects China as the case study to validate the feasibility of the models,a fire station(FS-JX)in Changsha.FS-JX station and its surrounding 9,117 fire risk points are selected as the fire service supply and demand points,respectively.A total of 196 simulation scenarios throughout a consecutiveweek are analyzed.Eventually,1,933,815 sets of valid sample data are obtained.The results showed that the TECA of FS-JX is 3.27 km^(2),which is far below the standard requirement of 7.00 km^(2) due to the traffic conditions.The visualization results showed that three rivers around FS-JX interrupt the continuity of its effective coverage.The proposed method can provide data support to optimize the locations of fire stations by accurately and dynamically determining the effective coverage of fire stations.展开更多
This study deals with base pressure management in a duct for various values of the Mach number(M),namely,Mach number corresponding to sonic and four supersonic conditions.In addition to the Mach number,the nozzle pres...This study deals with base pressure management in a duct for various values of the Mach number(M),namely,Mach number corresponding to sonic and four supersonic conditions.In addition to the Mach number,the nozzle pressure ratio(NPR),the area ratio,the rib dimension,and the duct length are influential parameters.The following specific values are examined at M=1,1.36,1.64,and 2,and NPRs between 1.5 and 10.The base pressure is determined by positioning ribs of varying heights at predetermined intervals throughout the length of the square duct.When the level of expansion is varied,it is seen that the base pressure initially drops for overexpanded flows and increases for under-expanded flows.When ribs are present,the flow field in the duct and pressure inside the duct fluctuate as the base pressure rises.Under-expanded flows can achieve a base pressure value that is suitably high without experiencing excessive changes in the duct flow in terms of static pressure if a rib height around 10%of the duct height close to the nozzle exit is considered.Rectangular rib passive control does not negatively affect the duct’s flow field.展开更多
The purpose of this work is to shed light on the effect of the pivot position on the surface pressure distribution over a 3D wing in different flight conditions.The study is intended to support the design and developm...The purpose of this work is to shed light on the effect of the pivot position on the surface pressure distribution over a 3D wing in different flight conditions.The study is intended to support the design and development of aerospace vehicles where stability analysis,performance optimization,and aircraft design are of primary importance.The following parameters are considered:Mach numbers(M)of 1.3,1.8,2.3,2.8,3.3,and 3.8,angle of incidence(θ)in the range from 5°to 25°,pivot position from h=0.2 to 1.The results of the CFD numerical simulations match available analytical data,thereby providing evidence for the reliability of the used approach.The findings provide valuable insights into the relationship between the surface pressure distribution,the Mach number and the angle of incidence.展开更多
Big data analytic techniques associated with machine learning algorithms are playing an increasingly important role in various application fields,including stock market investment.However,few studies have focused on f...Big data analytic techniques associated with machine learning algorithms are playing an increasingly important role in various application fields,including stock market investment.However,few studies have focused on forecasting daily stock market returns,especially when using powerful machine learning techniques,such as deep neural networks(DNNs),to perform the analyses.DNNs employ various deep learning algorithms based on the combination of network structure,activation function,and model parameters,with their performance depending on the format of the data representation.This paper presents a comprehensive big data analytics process to predict the daily return direction of the SPDR S&P 500 ETF(ticker symbol:SPY)based on 60 financial and economic features.DNNs and traditional artificial neural networks(ANNs)are then deployed over the entire preprocessed but untransformed dataset,along with two datasets transformed via principal component analysis(PCA),to predict the daily direction of future stock market index returns.While controlling for overfitting,a pattern for the classification accuracy of the DNNs is detected and demonstrated as the number of the hidden layers increases gradually from 12 to 1000.Moreover,a set of hypothesis testing procedures are implemented on the classification,and the simulation results show that the DNNs using two PCA-represented datasets give significantly higher classification accuracy than those using the entire untransformed dataset,as well as several other hybrid machine learning algorithms.In addition,the trading strategies guided by the DNN classification process based on PCA-represented data perform slightly better than the others tested,including in a comparison against two standard benchmarks.展开更多
Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the...Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.展开更多
A novel hybrid FRP-aluminum space truss was employed in a two-rut modular bridge superstructure, which is composed of standard structural units. The main objective of this work was to obtain a simple analytical soluti...A novel hybrid FRP-aluminum space truss was employed in a two-rut modular bridge superstructure, which is composed of standard structural units. The main objective of this work was to obtain a simple analytical solution that can conveniently predict the deflection of the proposed hybrid space truss bridge. The analytical formulae are expected to possess a straightforward format and simple calculation process. A simple description of the proposed bridge was introduced. The design formulae of the deflection were derived based on a simplified analytical plane truss model, which possessed hinge nodes and was subsequently simplified as two solid web beams during the theoretical derivation process. To validate the analytical model and formulae, numerical and experimental works were conducted and compared with the theoretical solutions. The results indicate that the analytical formulae provide higher deflection magnitudes with a difference of <1.5% compared with the experiments performed and <4.5% compared with the FE model used; the simplified plane truss is thus shown to be an effective analytical model for the derivation of deflection design formulae, which can conveniently calculate the deflection of the hybrid space truss bridge with satisfactory accuracy.展开更多
A method based on microjets is implemented to control the flow properties in a convergent-divergent nozzle undergoing a sudden expansion.Three different variants of this active control technique are explored numerical...A method based on microjets is implemented to control the flow properties in a convergent-divergent nozzle undergoing a sudden expansion.Three different variants of this active control technique are explored numerically by means of a finite-volume method for compressible fluid flow:with the first one,the control is implemented at the base,with the second at the wall,while the third one may be regarded as a combination of these.When jets are over-expanded,the control is not very effective.However,when a favourable pressure gradient is established in the nozzle,the control becomes effective,leading to an increase in the base pressure.展开更多
In the present study,the base pressure variations induced by the presence of a cavity,known to have a strong influence of the behaviour of supersonic projectiles,are investigated through numerical solution of the bala...In the present study,the base pressure variations induced by the presence of a cavity,known to have a strong influence of the behaviour of supersonic projectiles,are investigated through numerical solution of the balance equations for mass,momentum,and energy.An area ratio of four is considered and numerical simulations are carried out at Mach M=1.2,1.4,1.6,and 1.8 assuming no cavity or cavity locations 0.5D,1D,1.5D,and 2D.The inlet pressure of the nozzle is considered as a flow variable.The Taguchi method is also used,and the considered cases are then analyzed using a full factorial experimental design.The results show that the cavity is effective in increasing the base pressure for the conditions examined.For other nozzle pressure ratios,cavities do not lead to passive control due the change in the reattachment length.The distribution of wall pressure reveals that,in general,a cavity used to implement passive control of the base pressure does not adversely influence the flow pattern in the domain.展开更多
The application of abruptly enlarged flows to adjust the drag of aerodynamic vehicles using machine learning models has not been investigated previously.The process variables(Mach number(M),nozzle pressure ratio(η),a...The application of abruptly enlarged flows to adjust the drag of aerodynamic vehicles using machine learning models has not been investigated previously.The process variables(Mach number(M),nozzle pressure ratio(η),area ratio(α),and length to diameter ratio(γ))were numerically explored to address several aspects of this process,namely base pressure(β)and base pressure with cavity(βcav).In this work,the optimal base pressure is determined using the PCA-BAS-ENN based algorithm to modify the base pressure presetting accuracy,thereby regulating the base drag required for smooth flow of aerodynamic vehicles.Based on the identical dataset,the GA-BP and PSO-BP algorithms are also compared to thePCA-BAS-ENNalgorithm.The data for training and testing the algorithmswas derived using the regression equation developed using the Box-Behnken Design(BBD).The results show that the PCA-BAS-ENN model delivered highly accurate predictions when compared to the other two models.As a result,the advantages of these results are two-fold,providing:(i)a detailed examination of the efficiency of different neural network algorithms in dealing with a genuine aerodynamic problem,and(ii)helpful insights for regulating process variables to improve technological,operational,and financial factors,simultaneously.展开更多
In this study,a duct is considered and special attention is paid to a passive method for the control of the base pressure relying on the use of a cavity with a variable aspect ratio.The Mach number considered is 1.8,a...In this study,a duct is considered and special attention is paid to a passive method for the control of the base pressure relying on the use of a cavity with a variable aspect ratio.The Mach number considered is 1.8,and the area ratio of the duct is 2.56.In particular,two cavities are examined,their sizes being 3:3 and 6:3.The used L/D spans the interval 1–10 while the NPRs(nozzle pressure ratio)range from 2 to 9.The results show that the control becomes effective once the nozzles are correctly expanded or under-expanded.The pressure contours at different NPR and L/D are presented.It is shown that the NPR and cavity location strongly influence the base pressure.The NPR,Mach number,and cavity aspect ratio have a strong effect on the base pressure in the wake region.展开更多
Conventional refrigeration processes release ammonia and freon into the atmosphere,which results in global warming.These problems may be overcome by using thermoelectric modules because of the absence of coolants or r...Conventional refrigeration processes release ammonia and freon into the atmosphere,which results in global warming.These problems may be overcome by using thermoelectric modules because of the absence of coolants or refrigerants in these systems.However,the cooling performances of such modules are relatively small in comparison to those of conventional refrigerators.In this paper,the working principles of thermoelectric modules are discussed together with a review of different relevant aspects,namely:the thermoelectric materials,and their mechanical properties used to build thermoelectric devices,different types of thermoelectric devices available on the market,mathematical modeling of thermoelectric materials,and various applications of thermoelectric materials in different fields.展开更多
We study a firm that has a conventional plant and considers introducing a new plant as an alternative to generate electricity. The firm’s decision includes the optimal entry time for the new plant, and the optimal di...We study a firm that has a conventional plant and considers introducing a new plant as an alternative to generate electricity. The firm’s decision includes the optimal entry time for the new plant, and the optimal dispatch between the existing plant and the new plant after it has been constructed to maximize the expected profit over an infinite time horizon. Under geometric Brownian motion, we formulate the problems as non-regular mixed optimal stopping/control problem. Due to the intractability of the mixed problem, we decompose it into two auxiliary problems, and characterize the optimal strategies in closed-form by standard value-matching and smooth-pasting conditions. Our numerical example confirms our theoretical results.展开更多
Factors affecting equipment maintenance quality usually include personnel,equipment and facilities,raw materials and spare parts, craft, environment and quality management. These six factors affecting maintenance qual...Factors affecting equipment maintenance quality usually include personnel,equipment and facilities,raw materials and spare parts, craft, environment and quality management. These six factors affecting maintenance quality are not all the same degree. In order to find out which factor can influence equipment maintenance quality greatly and achieve sophisticated management,characteristic quantities of six factors are presented. A structural equation modeling( SEM) is designed using the six factors as latent variables and their characteristic quantities as the observed variable.According to the basic data obtained from the questionnaire survey,calculate the standardized regression weight by parameter estimation of the SEM. Then the key factors affecting the quality of the equipment maintenance are determined with the help of the standardized regression weight.展开更多
文摘The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays an important role in the central nervous system, where it is associated with glutamatergic signaling, and it is widely involved in inflammatory processes. Thus, diseases involving copper(Ⅱ) dyshomeostasis often have neurological symptoms, as exemplified by Alzheimer's and other diseases(such as Parkinson's and Wilson's diseases). Moreover, imbalanced copper ion concentrations have also been associated with diabetes and certain types of cancer, including glioma. In this paper, we propose a comprehensive overview of recent results that show the importance of these metal ions in several pathologies, mainly Alzheimer's disease, through the lens of the development and use of copper chelators as research compounds and potential therapeutics if included in multi-target hybrid drugs. Seeing how copper homeostasis is important for the well-being of animals as well as humans, we shortly describe the state of the art regarding the effects of copper and its chelators in agriculture, livestock rearing, and aquaculture, as ingredients for the formulation of feed supplements as well as to prevent the effects of pollution on animal productions.
文摘Purpose:This study investigates whether publication-centric incentive systems,introduced through the National Scientific Accreditation(ASN:Abilitazione Scientifica Nazionale)for professorships in Italy in 2012,contribute to adopting“salami publishing”strategies among Italian academics.Design/methodology/approach:A longitudinal bibliometric analysis was conducted on the publication records of over 25,000 Italian science professors to examine changes in publication output and the originality of their work following the implementation of the ASN.Findings:The analysis revealed a significant increase in publication output after the ASN’s introduction,along with a concurrent decline in the originality of publications.However,no evidence was found linking these trends to increased salami slicing practices among the observed researchers.Research limitations:Given the size of our observation field,we propose an innovative indirect approach based on the degree of originality of publications’bibliographies.We know that bibliographic coupling cannot capture salami publications per se,but only topically-related records.On the other hand,controlling for the author’s specialization level in the period,we believe that a higher level of bibliographic coupling in his scientific output can signal a change in his strategy of disseminating the results of his research.The relatively low R-squared values in our models(0.3-0.4)reflect the complexity of the phenomenon under investigation,revealing the presence of unmeasured factors influencing the outcomes,and future research should explore additional variables or alternative models that might account for a greater proportion of the variability.Despite this limitation,the significant predictors identified in our analysis provide valuable insights into the key factors driving the observed outcomes.Practical implications:The results of the study support those who argue that quantitative research assessment frameworks have had very positive effects and should not be dismissed,contrary to the claims of those evoking the occurrence of side effects that do not appear in the empirical analyses.Originality/value:This study provides empirical evidence on the impact of the ASN on publication behaviors in a huge micro-level dataset,contributing to the broader discourse on the effects of quantitative research assessments on academic publishing practices.
基金Ministry of Education,Center for Scientific Research and Development of Higher Education Institutions“Innovative Application of Virtual Simulation Technology in Vocational Education Teaching”Special Project,Project No.ZJXF2022110.
文摘This study presents an innovative approach to calculating the failure probability of slopes by incorporating fuzzylimit-state functions,a method that significantly enhances the accuracy and efficiency of slope stability analysis.Unlike traditional probabilistic techniques,this approach utilizes a least squares support vector machine(LSSVM)optimized with a grey wolf optimizer(GWO)and K-fold cross-validation(CV)to approximate the limit-statefunction,thus reducing computational complexity.The novelty of this work lies in its application to one-dimensional(1D),two-dimensional(2D),and three-dimensional(3D)slope models,demonstrating its versatility andhigh precision.The proposed method consistently achieves error margins within 3%of Monte Carlo simulation(MCS)results,while substantially reducing computation time,particularly for 2D and 3D models.This makes theapproach highly practical for real-world engineering applications.Furthermore,by applying fuzzy mathematics tohandle uncertainties in geotechnical properties,the method offers a more realistic and comprehensive understandingof slope stability.As water is the main factor influencing the stability of slopes,this aspect is investigatedby calculating the phreatic line after the change in water level.Relevant examples are used to show that the failureprobability of a slope under water wading condition can increase by more than 20%(increase rates in 1D,2D and3D conditions being 25%,27%and 31%,respectively)compared with the natural condition.The influence ofdiverse fuzzy membership functions—linear,normal,and Cauchy—on failure probability is also considered.Thisresearch not only provides a strategy for better calculation of the slope failure probability but also pioneers theintegration of computational intelligence,fuzzy logic and fluid-dynamics in geotechnical engineering,presentingan innovative and efficient tool for slope stability analysis.
基金funded by Universiti Tenaga Nasional(UNITEN),Malaysia for supporting this research under the Dato'Low Tuck Kwong International Grant,project code 20238002DLTKsupport for this work from the Ministry of Higher EducationMalaysia through the Higher Institution Center of Excellence(HICoE 2023-JPT(BPKI)1000/016/018/34(5))program+2 种基金supported by Tenaga Nasional Berhad(TNB)and UNITEN through the BOLD Refresh Postdoctoral Fellowships under Grant J510050002-IC-6 BOLDREFRESH2023-Centre of ExcellencePrince Sultan University for their supportIndustrial Technology Division,Malaysian Nuclear Agency for their support in this research work.
文摘Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.
文摘Purpose:Scholars face an unprecedented ever increasing demand for acting as reviewers for journals,recruitment and promotion committees,granting agencies,and research assessment agencies.Consequently,journal editors face an ever increasing scarcity of experts willing to act as reviewers.It is not infrequent that reviews diverge,which forces editors to recur to additional reviewers or make a final decision on their own.The purpose of the proposed bibliometric system is to support of editors’accept/reject decisions in such situations.Design/methodology/approach:We analyse nearly two million 2017 publications and their scholarly impact,measured by normalized citations.Based on theory and previous literature,we extrapolated the publication traits of text,byline,and bibliographic references expected to be associated with future citations.We then fitted a regression model with the outcome variable as the scholarly impact of the publication and the independent variables as the above non-scientific traits,controlling for fixed effects at the journal level.Findings:Non-scientific factors explained more than 26%of the paper’s impact,with slight variation across disciplines.On average,OA articles have a 7%greater impact than non-OA articles.A 1%increase in the number of references was associated with an average increase of 0.27%in impact.Higher-impact articles in the reference list,the number of authors and of countries in the byline,the article length,and the average impact of co-authors’past publications all show a positive association with the article’s impact.Female authors,authors from English-speaking countries,and the average age of the article’s references show instead a negative association.Research limitations:The selected non-scientific factors are the only observable and measurable ones to us,but we cannot rule out the presence of significant omitted variables.Using citations as a measure of impact has well-known limitations and overlooks other forms of scholarly influence.Additionally,the large dataset constrained us to one year’s global publications,preventing us from capturing and accounting for time effects.Practical implications:This study provides journal editors with a quantitative model that complements peer reviews,particularly when reviewer evaluations diverge.By incorporating non-scientific factors that significantly predict a paper’s future impact,editors can make more informed decisions,reduce reliance on additional reviewers,and improve the efficiency and fairness of the manuscript selection process.Originality/value:To the best of our knowledge,this study is the first one to specifically address the problem of supporting editors in any field in their decisions on submitted manuscripts with a quantitative model.Previous works have generally investigated the relationship between a few of the above publication traits and their impact or the agreement between peer-review and bibliometric evaluations of publications.
基金funded by National Natural Science Foundation of China (No.60574071)
文摘For the purpose of realizing the information visualization of hydropower engineering management, we construeted three kinds of graphics models sorted by hierarchy for system modelling, employed the construction simulation system to simulate the real-time construction behaviours, introduced the graphics rendering system to organize and update the virtual scene, and designed the interaction system to respond to the user-initiated and simulation-initiated events. So, the real-time, interactive visualization aided system of hydropower engineering management is developed. Eventually, the effectiveness and capabilities of the system are showed through the application examples in China.
基金support from the National Natural Science Foundation of China (No.52204202)the Hunan Provincial Natural Science Foundation of China (No.2023JJ40058)the Science and Technology Program of Hunan Provincial Departent of Transportation (No.202122).
文摘In recent years,frequent fire disasters have led to enormous damage in China.Effective firefighting rescues can minimize the losses caused by fires.During the rescue processes,the travel time of fire trucks can be severely affected by traffic conditions,changing the effective coverage of fire stations.However,it is still challenging to determine the effective coverage of fire stations considering dynamic traffic conditions.This paper addresses this issue by combining the traveling time calculationmodelwith the effective coverage simulationmodel.In addition,it proposes a new index of total effective coverage area(TECA)based on the time-weighted average of the effective coverage area(ECA)to evaluate the urban fire services.It also selects China as the case study to validate the feasibility of the models,a fire station(FS-JX)in Changsha.FS-JX station and its surrounding 9,117 fire risk points are selected as the fire service supply and demand points,respectively.A total of 196 simulation scenarios throughout a consecutiveweek are analyzed.Eventually,1,933,815 sets of valid sample data are obtained.The results showed that the TECA of FS-JX is 3.27 km^(2),which is far below the standard requirement of 7.00 km^(2) due to the traffic conditions.The visualization results showed that three rivers around FS-JX interrupt the continuity of its effective coverage.The proposed method can provide data support to optimize the locations of fire stations by accurately and dynamically determining the effective coverage of fire stations.
文摘This study deals with base pressure management in a duct for various values of the Mach number(M),namely,Mach number corresponding to sonic and four supersonic conditions.In addition to the Mach number,the nozzle pressure ratio(NPR),the area ratio,the rib dimension,and the duct length are influential parameters.The following specific values are examined at M=1,1.36,1.64,and 2,and NPRs between 1.5 and 10.The base pressure is determined by positioning ribs of varying heights at predetermined intervals throughout the length of the square duct.When the level of expansion is varied,it is seen that the base pressure initially drops for overexpanded flows and increases for under-expanded flows.When ribs are present,the flow field in the duct and pressure inside the duct fluctuate as the base pressure rises.Under-expanded flows can achieve a base pressure value that is suitably high without experiencing excessive changes in the duct flow in terms of static pressure if a rib height around 10%of the duct height close to the nozzle exit is considered.Rectangular rib passive control does not negatively affect the duct’s flow field.
文摘The purpose of this work is to shed light on the effect of the pivot position on the surface pressure distribution over a 3D wing in different flight conditions.The study is intended to support the design and development of aerospace vehicles where stability analysis,performance optimization,and aircraft design are of primary importance.The following parameters are considered:Mach numbers(M)of 1.3,1.8,2.3,2.8,3.3,and 3.8,angle of incidence(θ)in the range from 5°to 25°,pivot position from h=0.2 to 1.The results of the CFD numerical simulations match available analytical data,thereby providing evidence for the reliability of the used approach.The findings provide valuable insights into the relationship between the surface pressure distribution,the Mach number and the angle of incidence.
文摘Big data analytic techniques associated with machine learning algorithms are playing an increasingly important role in various application fields,including stock market investment.However,few studies have focused on forecasting daily stock market returns,especially when using powerful machine learning techniques,such as deep neural networks(DNNs),to perform the analyses.DNNs employ various deep learning algorithms based on the combination of network structure,activation function,and model parameters,with their performance depending on the format of the data representation.This paper presents a comprehensive big data analytics process to predict the daily return direction of the SPDR S&P 500 ETF(ticker symbol:SPY)based on 60 financial and economic features.DNNs and traditional artificial neural networks(ANNs)are then deployed over the entire preprocessed but untransformed dataset,along with two datasets transformed via principal component analysis(PCA),to predict the daily direction of future stock market index returns.While controlling for overfitting,a pattern for the classification accuracy of the DNNs is detected and demonstrated as the number of the hidden layers increases gradually from 12 to 1000.Moreover,a set of hypothesis testing procedures are implemented on the classification,and the simulation results show that the DNNs using two PCA-represented datasets give significantly higher classification accuracy than those using the entire untransformed dataset,as well as several other hybrid machine learning algorithms.In addition,the trading strategies guided by the DNN classification process based on PCA-represented data perform slightly better than the others tested,including in a comparison against two standard benchmarks.
基金Project(41030742) supported by the National Natural Science Foundation of ChinaProject(2009G010-c) supported by the Technological Research and Development Programs of the Ministry of Railways,China
文摘Based on the vehicle track coupling dynamics theory, a new spatial dynamic numerical model of vehicle track subgrade coupling system was established considering the interaction among different structural layers in the subgrade system. The dynamic responses of the coupled system were analyzed when the speed of train was 350 km/h and the transition was filled with graded broken stones mixed with 5% cement. The results indicate that the setting form of bridge-approach embankment section has little effect on the dynamic responses, thus designers can choose it on account of the practical circumstances. Because the location about 5 m from the bridge abutment has the greatest deformation, the stiffness within 0 5 m zone behind the abutment should be specially designed. The results of the study from vehicle track dynamics show that the maximum allowable track deflection angle should be 0.09% and the coefficient of subgrade reaction(K30) is greater than 190 MPa within the 0 5 m zone behind the abutment and greater than 150 MPa in other zones.
基金Project(2012CB026202)supported by the National Basic Research Program(973 Program)of ChinaProject(11372355)supported by the National Natural Science Foundation of ChinaProject(2012BAK05B)supported by the National Science and Technology Support Program of China
文摘A novel hybrid FRP-aluminum space truss was employed in a two-rut modular bridge superstructure, which is composed of standard structural units. The main objective of this work was to obtain a simple analytical solution that can conveniently predict the deflection of the proposed hybrid space truss bridge. The analytical formulae are expected to possess a straightforward format and simple calculation process. A simple description of the proposed bridge was introduced. The design formulae of the deflection were derived based on a simplified analytical plane truss model, which possessed hinge nodes and was subsequently simplified as two solid web beams during the theoretical derivation process. To validate the analytical model and formulae, numerical and experimental works were conducted and compared with the theoretical solutions. The results indicate that the analytical formulae provide higher deflection magnitudes with a difference of <1.5% compared with the experiments performed and <4.5% compared with the FE model used; the simplified plane truss is thus shown to be an effective analytical model for the derivation of deflection design formulae, which can conveniently calculate the deflection of the hybrid space truss bridge with satisfactory accuracy.
基金supported by the Structures and Materials(S&M)Research Lab of Prince Sultan University.
文摘A method based on microjets is implemented to control the flow properties in a convergent-divergent nozzle undergoing a sudden expansion.Three different variants of this active control technique are explored numerically by means of a finite-volume method for compressible fluid flow:with the first one,the control is implemented at the base,with the second at the wall,while the third one may be regarded as a combination of these.When jets are over-expanded,the control is not very effective.However,when a favourable pressure gradient is established in the nozzle,the control becomes effective,leading to an increase in the base pressure.
文摘In the present study,the base pressure variations induced by the presence of a cavity,known to have a strong influence of the behaviour of supersonic projectiles,are investigated through numerical solution of the balance equations for mass,momentum,and energy.An area ratio of four is considered and numerical simulations are carried out at Mach M=1.2,1.4,1.6,and 1.8 assuming no cavity or cavity locations 0.5D,1D,1.5D,and 2D.The inlet pressure of the nozzle is considered as a flow variable.The Taguchi method is also used,and the considered cases are then analyzed using a full factorial experimental design.The results show that the cavity is effective in increasing the base pressure for the conditions examined.For other nozzle pressure ratios,cavities do not lead to passive control due the change in the reattachment length.The distribution of wall pressure reveals that,in general,a cavity used to implement passive control of the base pressure does not adversely influence the flow pattern in the domain.
基金This research is supported by the Structures and Materials(S&M)Research Lab of Prince Sultan University.
文摘The application of abruptly enlarged flows to adjust the drag of aerodynamic vehicles using machine learning models has not been investigated previously.The process variables(Mach number(M),nozzle pressure ratio(η),area ratio(α),and length to diameter ratio(γ))were numerically explored to address several aspects of this process,namely base pressure(β)and base pressure with cavity(βcav).In this work,the optimal base pressure is determined using the PCA-BAS-ENN based algorithm to modify the base pressure presetting accuracy,thereby regulating the base drag required for smooth flow of aerodynamic vehicles.Based on the identical dataset,the GA-BP and PSO-BP algorithms are also compared to thePCA-BAS-ENNalgorithm.The data for training and testing the algorithmswas derived using the regression equation developed using the Box-Behnken Design(BBD).The results show that the PCA-BAS-ENN model delivered highly accurate predictions when compared to the other two models.As a result,the advantages of these results are two-fold,providing:(i)a detailed examination of the efficiency of different neural network algorithms in dealing with a genuine aerodynamic problem,and(ii)helpful insights for regulating process variables to improve technological,operational,and financial factors,simultaneously.
文摘In this study,a duct is considered and special attention is paid to a passive method for the control of the base pressure relying on the use of a cavity with a variable aspect ratio.The Mach number considered is 1.8,and the area ratio of the duct is 2.56.In particular,two cavities are examined,their sizes being 3:3 and 6:3.The used L/D spans the interval 1–10 while the NPRs(nozzle pressure ratio)range from 2 to 9.The results show that the control becomes effective once the nozzles are correctly expanded or under-expanded.The pressure contours at different NPR and L/D are presented.It is shown that the NPR and cavity location strongly influence the base pressure.The NPR,Mach number,and cavity aspect ratio have a strong effect on the base pressure in the wake region.
文摘Conventional refrigeration processes release ammonia and freon into the atmosphere,which results in global warming.These problems may be overcome by using thermoelectric modules because of the absence of coolants or refrigerants in these systems.However,the cooling performances of such modules are relatively small in comparison to those of conventional refrigerators.In this paper,the working principles of thermoelectric modules are discussed together with a review of different relevant aspects,namely:the thermoelectric materials,and their mechanical properties used to build thermoelectric devices,different types of thermoelectric devices available on the market,mathematical modeling of thermoelectric materials,and various applications of thermoelectric materials in different fields.
文摘We study a firm that has a conventional plant and considers introducing a new plant as an alternative to generate electricity. The firm’s decision includes the optimal entry time for the new plant, and the optimal dispatch between the existing plant and the new plant after it has been constructed to maximize the expected profit over an infinite time horizon. Under geometric Brownian motion, we formulate the problems as non-regular mixed optimal stopping/control problem. Due to the intractability of the mixed problem, we decompose it into two auxiliary problems, and characterize the optimal strategies in closed-form by standard value-matching and smooth-pasting conditions. Our numerical example confirms our theoretical results.
文摘Factors affecting equipment maintenance quality usually include personnel,equipment and facilities,raw materials and spare parts, craft, environment and quality management. These six factors affecting maintenance quality are not all the same degree. In order to find out which factor can influence equipment maintenance quality greatly and achieve sophisticated management,characteristic quantities of six factors are presented. A structural equation modeling( SEM) is designed using the six factors as latent variables and their characteristic quantities as the observed variable.According to the basic data obtained from the questionnaire survey,calculate the standardized regression weight by parameter estimation of the SEM. Then the key factors affecting the quality of the equipment maintenance are determined with the help of the standardized regression weight.
