To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force...To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force distribution,deformation development,and crack propagation characteristics of a framed anti-sliding structure(FAS)under landslide thrust up to the point of failure.Results show that the maximum bending moment and its increase rate in the fore pile are greater than those in the rear pile,with the maximum bending moment of the fore pile approximately 1.1 times that of the rear pile.When the FAS fails,the displacement at the top of the fore pile is significantly greater,about 1.27 times that of the rear pile in the experiment.Major cracks develop at locations corresponding to the peak bending moments.Small transverse cracks initially appear on the upper surface at the intersection between the primary beam and rear pile and then spread to the side of the structure.At the failure stage,major cracks are observed at the pil-beam intersections and near the anchor points.Strengthening flexural stiffness at intersections where major cracks occur can improve the overall thrust-deformation coordination of the FAS,thereby maximizing its performance.展开更多
In eukaryotic cells, initiation of protein translation is to recruit the ribosome to a specific mRNA, which is generally dependent on the 5＇ cap structure. However, protein translation can also be initiated in a cap-...In eukaryotic cells, initiation of protein translation is to recruit the ribosome to a specific mRNA, which is generally dependent on the 5＇ cap structure. However, protein translation can also be initiated in a cap-independent manner by using a cis-regulatory element termed the internal ribosome entry site （IRES）. The first experimentally validated IRES was reported in the poliovirus （Pelletier and Sonenberg, 1988）. Then eukaryotic cellular mRNAs were also validated to contain IRES elements.展开更多
Based on the method of reverberation ray matrix（MRRM）, a reverberation matrix for planar framed structures composed of anisotropic Timoshenko（T） beam members containing completely hinged joints is developed for st...Based on the method of reverberation ray matrix（MRRM）, a reverberation matrix for planar framed structures composed of anisotropic Timoshenko（T） beam members containing completely hinged joints is developed for static analysis of such structures.In the MRRM for dynamic analysis, amplitudes of arriving and departing waves for joints are chosen as unknown quantities. However, for the present case of static analysis, displacements and rotational angles at the ends of each beam member are directly considered as unknown quantities. The expressions for stiffness matrices for anisotropic beam members are developed. A corresponding reverberation matrix is derived analytically for exact and unified determination on the displacements and internal forces at both ends of each member and arbitrary cross sectional locations in the structure. Numerical examples are given and compared with the finite element method（FEM） results to validate the present model. The characteristic parameter analysis is performed to demonstrate accuracy of the present model with the T beam theory in contrast with errors in the usual model based on the Euler-Bernoulli（EB） beam theory. The resulting reverberation matrix can be used for exact calculation of anisotropic framed structures as well as for parameter analysis of geometrical and material properties of the framed structures.展开更多
An autonomous underwater vehicle (AUV) must use an algorithm to plan its path to distant, mobile offshore objects. Because of the uneven distribution of obstacles in the real world, the efficiency of the algorithm dec...An autonomous underwater vehicle (AUV) must use an algorithm to plan its path to distant, mobile offshore objects. Because of the uneven distribution of obstacles in the real world, the efficiency of the algorithm decreases if the global environment is represented by regular grids with all of them at the highest resolution. The framed quadtree data structure is able to more efficiently represent the environment. When planning the path, the dynamic object is expressed instead as several static objects which are used by the path planner to update the path. By taking account of the characteristics of the framed quadtree, objects can be projected on the frame nodes to increase the precision of the path. Analysis and simulations showed the proposed planner could increase efficiency while improving the ability of the AUV to follow an object.展开更多
In this article, the analytical homogenization method of periodic discrete media（HPDM）and the numerical condensed wave finite element method（CWFEM） are employed to study the longitudinal and transverse vibrations ...In this article, the analytical homogenization method of periodic discrete media（HPDM）and the numerical condensed wave finite element method（CWFEM） are employed to study the longitudinal and transverse vibrations of framed structures. The valid frequency range of the HPDM is re-evaluated using the wave propagation feature identified by the CWFEM. The relative error of the wavenumber by the HPDM compared to that by the CWFEM is illustrated in functions of frequency and scale ratio. A parametric study on the thickness of the structure is carried out where the dispersion relation and the relative error are given for three different thicknesses. The dynamics of a finite structure such as natural frequency and forced response are also investigated using the HPDM and the CWFEM.展开更多
The non-uniform beam components are commonly used in engineering,while the method to analyze such component is not too satisfactory yet. A new non-uniform beam element with high precision was developed based on the no...The non-uniform beam components are commonly used in engineering,while the method to analyze such component is not too satisfactory yet. A new non-uniform beam element with high precision was developed based on the non-linear analysis and the static condensation. Based on the interpolation theory, the displacement fields of the three-node non-uniform Euler-Bernoulli beam element were constructed at first: the quintic Hermite interpolation polynomial was used for the lateral displacement field and the quadratic Lagrange interpolation polynomial for the axial displacement field. Then,based on the basic assumptions of non-uniform Euler-Bernoulli beam whose section properties were continuously varying along its centroidal axis, the linear and geometric stiffness matrices of the three-node non-uniform beam element were derived according to the nonlinear finite element theory. Finally,the degrees of freedom ( DOFs) of the middle node of the element were eliminated using the static condensation method, and a new two-node non-uniform beam element including axial-force effect was obtained. The results indicate that each bar needs to be meshed with only one element could get a fairly accurate solution when it is applied to the stability analyses.展开更多
The object of this study is to determine the seismic response of regular high-rise steel buildings with chevron-braced frames. Mechanics models of three buildings of 14, 18 and 20 stories are studied, all of them with...The object of this study is to determine the seismic response of regular high-rise steel buildings with chevron-braced frames. Mechanics models of three buildings of 14, 18 and 20 stories are studied, all of them with similar geometric characteristics in plant and elevation. These models are realized using prescriptions and parameters from venezuelan design codes. The seismic action is carry on through varius synthetic design spectrum compatible accelerograms defined by the seismic codes in this study, with three levels of intensity corresponding to three specific Limit States. Dynamic analysis is used to compute parameters of ductility, over strength and maximum displacements. From these results it can be concluded that chevron-braced frames presented a good overall performance and non V-braced frames show greater damage due to dynamic actions, validating non linear dynamic analysis as a very powerful tool to seismic-resistance design and chevron-braced frames as a very useful choice in improving the response of tall steel structures. since this lateral bracing system is absent from Venezuelan seismic codes.展开更多
Framed links in thickened torus is studied. We give an expression of torus knot in the Kauffman bracket skein algebra. From this expression and using the theory of Gr？bner bases, we drive the reduced polynomial of a ...Framed links in thickened torus is studied. We give an expression of torus knot in the Kauffman bracket skein algebra. From this expression and using the theory of Gr？bner bases, we drive the reduced polynomial of a framed link, which is an ambient isotopic invariant and can be computed feasibly.展开更多
The design provisions of current seismic codes are generally not very accurate for assessing effects of near-fault ground motions on reinforced concrete （r.c.） spatial frames, because only far-fault ground motions a...The design provisions of current seismic codes are generally not very accurate for assessing effects of near-fault ground motions on reinforced concrete （r.c.） spatial frames, because only far-fault ground motions are considered in the seismic codes. Strong near-fault earth- quakes are characterized by long-duration （horizontal） pulses and high values of the ratio ~PGA of the peak value of the vertical acceleration, PGAv, to the analogous value of the horizontal acceleration, PGAH, which can become critical for girders and columns. In this work, six- and twelve-storey r.c. spatial frames are designed according to the provisions of the Italian seismic code, considering the horizontal seismic loads acting （besides the gravity loads） alone or in combination with the vertical ones. The non- linear seismic analysis of the test structures is performed using a step-by-step procedure based on a two-parameter implicit integration scheme and an initial stress-like itera- tive procedure. A lumped plasticity model based on the Haar-K^n~m principle is adopted to model the inelastic behaviour of the frame members. For the numerical investigation, five near-fault ground motions with high values of the acceleration ratio C^p6A are considered. Moreover, following recent seismological studies, which allow the extraction of the largest （horizontal） pulse from a near-fault ground motion, five pulse-type （horizontal） ground motions are selected by comparing the original ground motion with the residual motion after the pulse has been extracted. The results of the nonlinear dynamic analysis carried out on the test structures highlighted thathorizontal and vertical components of near-fault ground motions may require additional consideration in the seis- mic codes.展开更多
A pilot study was conducted at Penn State University to determine whether the type of drywall joint compound would influence the shear strength of wood-frame stud walls sheathed with Gypsum Wall Board (GWB or drywall)...A pilot study was conducted at Penn State University to determine whether the type of drywall joint compound would influence the shear strength of wood-frame stud walls sheathed with Gypsum Wall Board (GWB or drywall). In this study, five 2438 mm by 2438 mm specimens were tested under in-plane cyclic racking loading following the CUREE loading protocol for light-frame wall systems. Three specimens were finished using non-cement based joint compound while the other two used cement based joint compound. Based on the experimental testing of the specimens, the results show that the use of cement based joint compound on drywall joints produces higher shear capacity for the wall system as compared to similar specimens finished with conventional non-cement based joint compound. The result of the study is particularly important for high seismic regions where interior stud walls in residential construction effectively take part in seismic resistance even though wood shear walls are normally used on exterior walls.展开更多
Under the rapidly advancing economic trends,people’s requirements for the functionality and architectural artistry of high-rise structures are constantly increasing,and in order to meet such modern requirements,it is...Under the rapidly advancing economic trends,people’s requirements for the functionality and architectural artistry of high-rise structures are constantly increasing,and in order to meet such modern requirements,it is necessary to diversify the functions of high-rise buildings and complicate the building form.At present,the main structural systems of high-rise buildings are:frame structure,shear wall structure,frame shear structure,and tube structure.Different structural systems determine the size of the load-bearing capacity,lateral stiffness,and seismic performance,as well as the amount of material used and the cost.This project is mainly concerned with the seismic design of frame shear structural systems,which are widely used today.展开更多
We investigate modular framed vertex operator algebras over an algebraically closed field F whose characteristic is different from 2 and 7.In particular,the rationality of modular framed vertex operator algebras is es...We investigate modular framed vertex operator algebras over an algebraically closed field F whose characteristic is different from 2 and 7.In particular,the rationality of modular framed vertex operator algebras is established.For a modular code vertex operator algebra,the irreducible modules are constructed and classified.Moreover,a Z[1/2]-form for any framed vertex operator algebra over C is constructed.As a result,one can obtain a modular framed vertex operator algebra from any framed vertex operator algebra over C.展开更多
In this paper,we define the evolute and focal surface of a spacelike framed curve with lightlike components in Minkowski 3-space.It is a generalization of the previous results of regular spacelike curves,since singula...In this paper,we define the evolute and focal surface of a spacelike framed curve with lightlike components in Minkowski 3-space.It is a generalization of the previous results of regular spacelike curves,since singularities are allowed in the original spacelike curves studied by spacelike framed curves with lightlike components.Meanwhile,we show a new geometric invariant to characterise singularities of the focal surface.Then,the classification theorem and recognition theorem for the singularities of the focal surface in generic are also given.展开更多
We introduce null surfaces(or nullcone fronts)of pseudo-spherical spacelike framed curves in the three-dimensional anti-de Sitter space.These surfaces are formed by the light rays emitted from points on anti-de Sitter...We introduce null surfaces(or nullcone fronts)of pseudo-spherical spacelike framed curves in the three-dimensional anti-de Sitter space.These surfaces are formed by the light rays emitted from points on anti-de Sitter spacelike framed curves.We then classify singularities of the nullcone front of a pseudo-spherical spacelike framed curve and show how these singularities are related to the singularities of the associated framed curve.We also define a family of functions called the Anti-de Sitter distance-squared functions to explain the nullcone front of a pseudo-spherical spacelike framed curve as a wavefront from the viewpoint of the Legendrian singularity theory.We finally provide some examples to illustrate the results of this paper.展开更多
Bushfire-related building losses cause adverse economic impacts to countries prone to bushfires.Building materials and components play a vital role in reducing these impacts.However,due to high costs of experimental s...Bushfire-related building losses cause adverse economic impacts to countries prone to bushfires.Building materials and components play a vital role in reducing these impacts.However,due to high costs of experimental studies and lack of numerical studies,the heat transfer behavior of building’s external components in bushfire-prone areas has not been adequately investigated.Often large-scale heat transfer models are developed using Computational Fluid Dynamics(CFD)tools,and the availability of CFD models for heat transfer in building components improves the understanding of the behavior of systems and systems of systems.Therefore,this paper uses a numerical modeling approach to investigate the bushfire/wildfire resistance of external Light gauge Steel Framed(LSF)wall systems.Both full-scale and small-scale heat transfer models were developed for the LSF wall systems.Experimental results of six internal and external LSF wall systems with varying plasterboard thickness and cladding material were used to validate the developed models.The study was then extended to investigate the bushfire resistance of seven external wall systems under two different bushfire flame zone conditions.The results illustrate the significant effects of fire curves,LSF wall components and configuration on the heat transfer across the walls.They have shown 1)the favorable performance of steel cladding and Autoclaved Aerated Concrete(AAC)panels when used on the external side of wall systems and 2)the adequacy of thin-walled steel studs’load-bearing capacity during bushfire exposures.This study has shown that most of the investigated external LSF walls could be reused with cost-effective retrofitting such as replacing the Fire Side(FS)steel cladding after bushfire exposures.Overall,this study has advanced the understanding of the behavior of external light steel framed walls under bushfire flame zone conditions.展开更多
This article describes a novel approach for deciding optimal horizontal extent of soil domain to be used for finite element based numerical dynamic soil structure interaction(SSI)studies.SSI model for a 12 storied bui...This article describes a novel approach for deciding optimal horizontal extent of soil domain to be used for finite element based numerical dynamic soil structure interaction(SSI)studies.SSI model for a 12 storied building frame,supported on pile foundation-soil system,is developed in the finite element based software framework,OpenSEES.Three different structure-foundation configurations are analyzed under different ground motion characteristics.Lateral extent of soil domain,along with the soil properties,were varied exhaustively for a particular structural configuration.Based on the reduction in the variation of acceleration response at different locations in the SSI system(quantified by normalized root mean square error,NRMSE),the optimum lateral extent of the soil domain is prescribed for various structural widths,soil types and peak ground acceleration levels of ground motion.Compared to the past studies,error estimation analysis shows that the relationships prescribed in the present study are credible and more inclusive of the various factors that influence SSI.These relationships can be readily applied for deciding upon the lateral extent of the soil domain for conducting precise SSI analysis with reduced computational time.展开更多
The Internet of Vehicles (IoV) has become an important direction in the field of intelligent transportation, in which vehicle positioning is a crucial part. SLAM (Simultaneous Localization and Mapping) technology play...The Internet of Vehicles (IoV) has become an important direction in the field of intelligent transportation, in which vehicle positioning is a crucial part. SLAM (Simultaneous Localization and Mapping) technology plays a crucial role in vehicle localization and navigation. Traditional Simultaneous Localization and Mapping (SLAM) systems are designed for use in static environments, and they can result in poor performance in terms of accuracy and robustness when used in dynamic environments where objects are in constant movement. To address this issue, a new real-time visual SLAM system called MG-SLAM has been developed. Based on ORB-SLAM2, MG-SLAM incorporates a dynamic target detection process that enables the detection of both known and unknown moving objects. In this process, a separate semantic segmentation thread is required to segment dynamic target instances, and the Mask R-CNN algorithm is applied on the Graphics Processing Unit (GPU) to accelerate segmentation. To reduce computational cost, only key frames are segmented to identify known dynamic objects. Additionally, a multi-view geometry method is adopted to detect unknown moving objects. The results demonstrate that MG-SLAM achieves higher precision, with an improvement from 0.2730 m to 0.0135 m in precision. Moreover, the processing time required by MG-SLAM is significantly reduced compared to other dynamic scene SLAM algorithms, which illustrates its efficacy in locating objects in dynamic scenes.展开更多
The rapid advancement of Artificial Intelligence(AI)and Large Language Models(LLMs)has led to their increasing integration into various domains,from text generation and translation to question-answering.However,a crit...The rapid advancement of Artificial Intelligence(AI)and Large Language Models(LLMs)has led to their increasing integration into various domains,from text generation and translation to question-answering.However,a critical question remains:do these sophisticated models,much like humans,exhibit susceptibility to cognitive biases?Understanding the presence and nature of such biases in AI is paramount for assessing their reliability,enhancing their performance,and predicting their societal impact.This research specifically investigates the susceptibility of Google’s Gemini 1.5 Pro and DeepSeek,two prominent LLMs,to framing effects and confirmation bias.The study meticulously designed a series of experimental trials,systematically manipulating information proportions and presentation orders to evaluate these biases.In the framing effect experiment,a genetic testing decision-making scenario was constructed.The proportion of positive and negative information(e.g.,20%,50%,or 80%positive)and their presentation order were varied.The models’inclination towards undergoing genetic testing was recorded.For the confirmation bias experiment,two reports-one positive and one negative-about“RoboTaxi”autonomous vehicles were provided.The proportion of erroneous information within these reports(10%,30%,and 50%)and their presentation order were systematically altered,and the models’support for each report was assessed.The findings demonstrate that both Gemini 1.5 Pro and DeepSeek are susceptible to framing effects.In the genetic testing scenario,their decision-making was primarily influenced by the proportion of positive and negative information presented.When the proportion of positive information was higher,both models showed a greater inclination to recommend or proceed with genetic testing.Conversely,a higher proportion of negative information led to greater caution or a tendency not to recommend the testing.Importantly,the order in which this information was presented did not significantly influence their decisions in the framing effect scenarios.Regarding confirmation bias,the two models exhibited distinct behaviors.Gemini 1.5 Pro did not show an overall preference for either positive or negative reports.However,its judgments were significantly influenced by the order of information presentation,demonstrating a“recency effect,”meaning it tended to support the report presented later.The proportion of erroneous information within the reports had no significant impact on Gemini 1.5 Pro’s decisions.In contrast,DeepSeek exhibited an overall confirmation bias,showing a clear preference for positive reports.Similar to Gemini 1.5 Pro,DeepSeek’s decisions were also significantly affected by the order of information presentation,while the proportion of misinformation had no significant effect.These results reveal human-like cognitive vulnerabilities in advanced LLMs,highlighting critical challenges to their reliability and objectivity in decision-making processes.Gemini 1.5 Pro’s sensitivity to presentation order and DeepSeek’s general preference for positive information,coupled with its sensitivity to order,underscore the need for careful evaluation of potential cognitive biases during the development and application of AI.The study suggests that effective measures are necessary to mitigate these biases and prevent potential negative societal impacts.Future research should include a broader range of models for comparative analysis and explore more complex interactive scenarios to further understand and address these phenomena.The findings contribute significantly to understanding the limitations and capabilities of current AI systems,guiding their responsible development,and anticipating their potential societal implications.展开更多
基金The National Natural Science Foundation of China(No.52078427).
文摘To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force distribution,deformation development,and crack propagation characteristics of a framed anti-sliding structure(FAS)under landslide thrust up to the point of failure.Results show that the maximum bending moment and its increase rate in the fore pile are greater than those in the rear pile,with the maximum bending moment of the fore pile approximately 1.1 times that of the rear pile.When the FAS fails,the displacement at the top of the fore pile is significantly greater,about 1.27 times that of the rear pile in the experiment.Major cracks develop at locations corresponding to the peak bending moments.Small transverse cracks initially appear on the upper surface at the intersection between the primary beam and rear pile and then spread to the side of the structure.At the failure stage,major cracks are observed at the pil-beam intersections and near the anchor points.Strengthening flexural stiffness at intersections where major cracks occur can improve the overall thrust-deformation coordination of the FAS,thereby maximizing its performance.
基金supported by the grants from National Natural Science Foundation of China (Nos. 61571223 and 61171191)
文摘In eukaryotic cells, initiation of protein translation is to recruit the ribosome to a specific mRNA, which is generally dependent on the 5＇ cap structure. However, protein translation can also be initiated in a cap-independent manner by using a cis-regulatory element termed the internal ribosome entry site （IRES）. The first experimentally validated IRES was reported in the poliovirus （Pelletier and Sonenberg, 1988）. Then eukaryotic cellular mRNAs were also validated to contain IRES elements.
基金Project supported by the Program for New Century Excellent Talents in Universities(NCET)by the Ministry of Education of China(No.NCET-04-0373)
文摘Based on the method of reverberation ray matrix（MRRM）, a reverberation matrix for planar framed structures composed of anisotropic Timoshenko（T） beam members containing completely hinged joints is developed for static analysis of such structures.In the MRRM for dynamic analysis, amplitudes of arriving and departing waves for joints are chosen as unknown quantities. However, for the present case of static analysis, displacements and rotational angles at the ends of each beam member are directly considered as unknown quantities. The expressions for stiffness matrices for anisotropic beam members are developed. A corresponding reverberation matrix is derived analytically for exact and unified determination on the displacements and internal forces at both ends of each member and arbitrary cross sectional locations in the structure. Numerical examples are given and compared with the finite element method（FEM） results to validate the present model. The characteristic parameter analysis is performed to demonstrate accuracy of the present model with the T beam theory in contrast with errors in the usual model based on the Euler-Bernoulli（EB） beam theory. The resulting reverberation matrix can be used for exact calculation of anisotropic framed structures as well as for parameter analysis of geometrical and material properties of the framed structures.
基金Supported by the National Natural Science Foundation of China under Grant No. 60875071
文摘An autonomous underwater vehicle (AUV) must use an algorithm to plan its path to distant, mobile offshore objects. Because of the uneven distribution of obstacles in the real world, the efficiency of the algorithm decreases if the global environment is represented by regular grids with all of them at the highest resolution. The framed quadtree data structure is able to more efficiently represent the environment. When planning the path, the dynamic object is expressed instead as several static objects which are used by the path planner to update the path. By taking account of the characteristics of the framed quadtree, objects can be projected on the frame nodes to increase the precision of the path. Analysis and simulations showed the proposed planner could increase efficiency while improving the ability of the AUV to follow an object.
文摘In this article, the analytical homogenization method of periodic discrete media（HPDM）and the numerical condensed wave finite element method（CWFEM） are employed to study the longitudinal and transverse vibrations of framed structures. The valid frequency range of the HPDM is re-evaluated using the wave propagation feature identified by the CWFEM. The relative error of the wavenumber by the HPDM compared to that by the CWFEM is illustrated in functions of frequency and scale ratio. A parametric study on the thickness of the structure is carried out where the dispersion relation and the relative error are given for three different thicknesses. The dynamics of a finite structure such as natural frequency and forced response are also investigated using the HPDM and the CWFEM.
文摘The non-uniform beam components are commonly used in engineering,while the method to analyze such component is not too satisfactory yet. A new non-uniform beam element with high precision was developed based on the non-linear analysis and the static condensation. Based on the interpolation theory, the displacement fields of the three-node non-uniform Euler-Bernoulli beam element were constructed at first: the quintic Hermite interpolation polynomial was used for the lateral displacement field and the quadratic Lagrange interpolation polynomial for the axial displacement field. Then,based on the basic assumptions of non-uniform Euler-Bernoulli beam whose section properties were continuously varying along its centroidal axis, the linear and geometric stiffness matrices of the three-node non-uniform beam element were derived according to the nonlinear finite element theory. Finally,the degrees of freedom ( DOFs) of the middle node of the element were eliminated using the static condensation method, and a new two-node non-uniform beam element including axial-force effect was obtained. The results indicate that each bar needs to be meshed with only one element could get a fairly accurate solution when it is applied to the stability analyses.
文摘The object of this study is to determine the seismic response of regular high-rise steel buildings with chevron-braced frames. Mechanics models of three buildings of 14, 18 and 20 stories are studied, all of them with similar geometric characteristics in plant and elevation. These models are realized using prescriptions and parameters from venezuelan design codes. The seismic action is carry on through varius synthetic design spectrum compatible accelerograms defined by the seismic codes in this study, with three levels of intensity corresponding to three specific Limit States. Dynamic analysis is used to compute parameters of ductility, over strength and maximum displacements. From these results it can be concluded that chevron-braced frames presented a good overall performance and non V-braced frames show greater damage due to dynamic actions, validating non linear dynamic analysis as a very powerful tool to seismic-resistance design and chevron-braced frames as a very useful choice in improving the response of tall steel structures. since this lateral bracing system is absent from Venezuelan seismic codes.
基金Supported by Guangdong Province Innovation Talent Project for Youths(Grant No.2015KQNCX107)Guangdong University of Education Special Fund for Doctoral Research(Grant No.2016ARF06)
文摘Framed links in thickened torus is studied. We give an expression of torus knot in the Kauffman bracket skein algebra. From this expression and using the theory of Gr？bner bases, we drive the reduced polynomial of a framed link, which is an ambient isotopic invariant and can be computed feasibly.
文摘The design provisions of current seismic codes are generally not very accurate for assessing effects of near-fault ground motions on reinforced concrete （r.c.） spatial frames, because only far-fault ground motions are considered in the seismic codes. Strong near-fault earth- quakes are characterized by long-duration （horizontal） pulses and high values of the ratio ~PGA of the peak value of the vertical acceleration, PGAv, to the analogous value of the horizontal acceleration, PGAH, which can become critical for girders and columns. In this work, six- and twelve-storey r.c. spatial frames are designed according to the provisions of the Italian seismic code, considering the horizontal seismic loads acting （besides the gravity loads） alone or in combination with the vertical ones. The non- linear seismic analysis of the test structures is performed using a step-by-step procedure based on a two-parameter implicit integration scheme and an initial stress-like itera- tive procedure. A lumped plasticity model based on the Haar-K^n~m principle is adopted to model the inelastic behaviour of the frame members. For the numerical investigation, five near-fault ground motions with high values of the acceleration ratio C^p6A are considered. Moreover, following recent seismological studies, which allow the extraction of the largest （horizontal） pulse from a near-fault ground motion, five pulse-type （horizontal） ground motions are selected by comparing the original ground motion with the residual motion after the pulse has been extracted. The results of the nonlinear dynamic analysis carried out on the test structures highlighted thathorizontal and vertical components of near-fault ground motions may require additional consideration in the seis- mic codes.
文摘A pilot study was conducted at Penn State University to determine whether the type of drywall joint compound would influence the shear strength of wood-frame stud walls sheathed with Gypsum Wall Board (GWB or drywall). In this study, five 2438 mm by 2438 mm specimens were tested under in-plane cyclic racking loading following the CUREE loading protocol for light-frame wall systems. Three specimens were finished using non-cement based joint compound while the other two used cement based joint compound. Based on the experimental testing of the specimens, the results show that the use of cement based joint compound on drywall joints produces higher shear capacity for the wall system as compared to similar specimens finished with conventional non-cement based joint compound. The result of the study is particularly important for high seismic regions where interior stud walls in residential construction effectively take part in seismic resistance even though wood shear walls are normally used on exterior walls.
文摘Under the rapidly advancing economic trends,people’s requirements for the functionality and architectural artistry of high-rise structures are constantly increasing,and in order to meet such modern requirements,it is necessary to diversify the functions of high-rise buildings and complicate the building form.At present,the main structural systems of high-rise buildings are:frame structure,shear wall structure,frame shear structure,and tube structure.Different structural systems determine the size of the load-bearing capacity,lateral stiffness,and seismic performance,as well as the amount of material used and the cost.This project is mainly concerned with the seismic design of frame shear structural systems,which are widely used today.
基金supported by the Simons Foundation(Grant No.634104)Ching Hung Lam was supported by Ministry of Science and Technology(Grant No.104-2115-M-001-004-MY3)supported by National Natural Science Foundation of China(Grant No.12071314)。
文摘We investigate modular framed vertex operator algebras over an algebraically closed field F whose characteristic is different from 2 and 7.In particular,the rationality of modular framed vertex operator algebras is established.For a modular code vertex operator algebra,the irreducible modules are constructed and classified.Moreover,a Z[1/2]-form for any framed vertex operator algebra over C is constructed.As a result,one can obtain a modular framed vertex operator algebra from any framed vertex operator algebra over C.
基金Supported by National Natural Science Foundation of China(Grant No.11671070)。
文摘In this paper,we define the evolute and focal surface of a spacelike framed curve with lightlike components in Minkowski 3-space.It is a generalization of the previous results of regular spacelike curves,since singularities are allowed in the original spacelike curves studied by spacelike framed curves with lightlike components.Meanwhile,we show a new geometric invariant to characterise singularities of the focal surface.Then,the classification theorem and recognition theorem for the singularities of the focal surface in generic are also given.
文摘We introduce null surfaces(or nullcone fronts)of pseudo-spherical spacelike framed curves in the three-dimensional anti-de Sitter space.These surfaces are formed by the light rays emitted from points on anti-de Sitter spacelike framed curves.We then classify singularities of the nullcone front of a pseudo-spherical spacelike framed curve and show how these singularities are related to the singularities of the associated framed curve.We also define a family of functions called the Anti-de Sitter distance-squared functions to explain the nullcone front of a pseudo-spherical spacelike framed curve as a wavefront from the viewpoint of the Legendrian singularity theory.We finally provide some examples to illustrate the results of this paper.
基金the Australian Research Council(ARC Grant Nos.DE180101598 and DP200102704)Queensland University of Technology(QUT)for providing financial support.
文摘Bushfire-related building losses cause adverse economic impacts to countries prone to bushfires.Building materials and components play a vital role in reducing these impacts.However,due to high costs of experimental studies and lack of numerical studies,the heat transfer behavior of building’s external components in bushfire-prone areas has not been adequately investigated.Often large-scale heat transfer models are developed using Computational Fluid Dynamics(CFD)tools,and the availability of CFD models for heat transfer in building components improves the understanding of the behavior of systems and systems of systems.Therefore,this paper uses a numerical modeling approach to investigate the bushfire/wildfire resistance of external Light gauge Steel Framed(LSF)wall systems.Both full-scale and small-scale heat transfer models were developed for the LSF wall systems.Experimental results of six internal and external LSF wall systems with varying plasterboard thickness and cladding material were used to validate the developed models.The study was then extended to investigate the bushfire resistance of seven external wall systems under two different bushfire flame zone conditions.The results illustrate the significant effects of fire curves,LSF wall components and configuration on the heat transfer across the walls.They have shown 1)the favorable performance of steel cladding and Autoclaved Aerated Concrete(AAC)panels when used on the external side of wall systems and 2)the adequacy of thin-walled steel studs’load-bearing capacity during bushfire exposures.This study has shown that most of the investigated external LSF walls could be reused with cost-effective retrofitting such as replacing the Fire Side(FS)steel cladding after bushfire exposures.Overall,this study has advanced the understanding of the behavior of external light steel framed walls under bushfire flame zone conditions.
基金The support and resources provided by Department of Civil Engineering,Indian Institute of Technology Guwahati and Ministry of Human Resources and Development(MHRD,Govt.of India),is gratefully acknowledged by the authors.
文摘This article describes a novel approach for deciding optimal horizontal extent of soil domain to be used for finite element based numerical dynamic soil structure interaction(SSI)studies.SSI model for a 12 storied building frame,supported on pile foundation-soil system,is developed in the finite element based software framework,OpenSEES.Three different structure-foundation configurations are analyzed under different ground motion characteristics.Lateral extent of soil domain,along with the soil properties,were varied exhaustively for a particular structural configuration.Based on the reduction in the variation of acceleration response at different locations in the SSI system(quantified by normalized root mean square error,NRMSE),the optimum lateral extent of the soil domain is prescribed for various structural widths,soil types and peak ground acceleration levels of ground motion.Compared to the past studies,error estimation analysis shows that the relationships prescribed in the present study are credible and more inclusive of the various factors that influence SSI.These relationships can be readily applied for deciding upon the lateral extent of the soil domain for conducting precise SSI analysis with reduced computational time.
基金funded by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(grant number 22KJD440001)Changzhou Science&Technology Program(grant number CJ20220232).
文摘The Internet of Vehicles (IoV) has become an important direction in the field of intelligent transportation, in which vehicle positioning is a crucial part. SLAM (Simultaneous Localization and Mapping) technology plays a crucial role in vehicle localization and navigation. Traditional Simultaneous Localization and Mapping (SLAM) systems are designed for use in static environments, and they can result in poor performance in terms of accuracy and robustness when used in dynamic environments where objects are in constant movement. To address this issue, a new real-time visual SLAM system called MG-SLAM has been developed. Based on ORB-SLAM2, MG-SLAM incorporates a dynamic target detection process that enables the detection of both known and unknown moving objects. In this process, a separate semantic segmentation thread is required to segment dynamic target instances, and the Mask R-CNN algorithm is applied on the Graphics Processing Unit (GPU) to accelerate segmentation. To reduce computational cost, only key frames are segmented to identify known dynamic objects. Additionally, a multi-view geometry method is adopted to detect unknown moving objects. The results demonstrate that MG-SLAM achieves higher precision, with an improvement from 0.2730 m to 0.0135 m in precision. Moreover, the processing time required by MG-SLAM is significantly reduced compared to other dynamic scene SLAM algorithms, which illustrates its efficacy in locating objects in dynamic scenes.
文摘The rapid advancement of Artificial Intelligence(AI)and Large Language Models(LLMs)has led to their increasing integration into various domains,from text generation and translation to question-answering.However,a critical question remains:do these sophisticated models,much like humans,exhibit susceptibility to cognitive biases?Understanding the presence and nature of such biases in AI is paramount for assessing their reliability,enhancing their performance,and predicting their societal impact.This research specifically investigates the susceptibility of Google’s Gemini 1.5 Pro and DeepSeek,two prominent LLMs,to framing effects and confirmation bias.The study meticulously designed a series of experimental trials,systematically manipulating information proportions and presentation orders to evaluate these biases.In the framing effect experiment,a genetic testing decision-making scenario was constructed.The proportion of positive and negative information(e.g.,20%,50%,or 80%positive)and their presentation order were varied.The models’inclination towards undergoing genetic testing was recorded.For the confirmation bias experiment,two reports-one positive and one negative-about“RoboTaxi”autonomous vehicles were provided.The proportion of erroneous information within these reports(10%,30%,and 50%)and their presentation order were systematically altered,and the models’support for each report was assessed.The findings demonstrate that both Gemini 1.5 Pro and DeepSeek are susceptible to framing effects.In the genetic testing scenario,their decision-making was primarily influenced by the proportion of positive and negative information presented.When the proportion of positive information was higher,both models showed a greater inclination to recommend or proceed with genetic testing.Conversely,a higher proportion of negative information led to greater caution or a tendency not to recommend the testing.Importantly,the order in which this information was presented did not significantly influence their decisions in the framing effect scenarios.Regarding confirmation bias,the two models exhibited distinct behaviors.Gemini 1.5 Pro did not show an overall preference for either positive or negative reports.However,its judgments were significantly influenced by the order of information presentation,demonstrating a“recency effect,”meaning it tended to support the report presented later.The proportion of erroneous information within the reports had no significant impact on Gemini 1.5 Pro’s decisions.In contrast,DeepSeek exhibited an overall confirmation bias,showing a clear preference for positive reports.Similar to Gemini 1.5 Pro,DeepSeek’s decisions were also significantly affected by the order of information presentation,while the proportion of misinformation had no significant effect.These results reveal human-like cognitive vulnerabilities in advanced LLMs,highlighting critical challenges to their reliability and objectivity in decision-making processes.Gemini 1.5 Pro’s sensitivity to presentation order and DeepSeek’s general preference for positive information,coupled with its sensitivity to order,underscore the need for careful evaluation of potential cognitive biases during the development and application of AI.The study suggests that effective measures are necessary to mitigate these biases and prevent potential negative societal impacts.Future research should include a broader range of models for comparative analysis and explore more complex interactive scenarios to further understand and address these phenomena.The findings contribute significantly to understanding the limitations and capabilities of current AI systems,guiding their responsible development,and anticipating their potential societal implications.
