Hinged booms are widely used in astrophysics missions;however,the trajectory and deployment velocity are difficult to control because they are usually driven by springs,which limits their application in narrow spaces....Hinged booms are widely used in astrophysics missions;however,the trajectory and deployment velocity are difficult to control because they are usually driven by springs,which limits their application in narrow spaces.Thus,a novel hinged boom is highly required to achieve motion controllability.Through an equivalent substitution between the cable drive loop and the binary link in topology,a type synthesis method for the cable-driven single-degree-of-freedom chain is proposed based on the single-open-chain(SOC)adding method.According to the configuration design,a novel cable-driven hinged boom is proposed,aiming to achieve boom synchronism.Then,to preload easily,a method that preload is applied and measured at the cable ends is adopted and the relationship between the initial preload and the target preload is deduced.By analyzing the distribution of cable tension,a new stiffness model is proposed thus a stiffness equation is obtained.Finally,the dynamic simulation analysis and zero-gravity deployment experiment of the hinged boom is carried out to verify its reliability.This research provides a new way for the type synthesis of cable-driven single-degree-of-freedom chain and a new model for analyzing cable-driven stiffness.Moreover,the novel cable-driven hinged boom obtained in this study can be well-applied in the field of aerospace.展开更多
To investigate the effect of higher modes on the displacement and inner forces in HWBB(hinged wall with buckling-restrained braces in base)-frame structure,distributed parameter models for both the HWBB-hinged frame s...To investigate the effect of higher modes on the displacement and inner forces in HWBB(hinged wall with buckling-restrained braces in base)-frame structure,distributed parameter models for both the HWBB-hinged frame structure and the HWBB-MRF(moment resisting frame)structure are built.The hinged wall is simplified as a flexural beam.BRBs(bucking-restrained braces)are simplified to a rotational spring.MRF is simplified to a shear beam.Vibration equations of distributed parameter models are derived.Natural periods,natural modes of vibration,inner forces and displacements of the distributed parameter models are derived based on the vibration equations using numerical methods.The effect of the relative stiffness ratio and the rotational stiffness ratio on the higher mode effects is investigated.For elastic structures,the global displacement and shear in MRF are predominantly controlled by the first mode,while the shear and bending moment in the wall are significantly affected by higher mode effects.The effect of the yielding of BRB on the inner forces distribution in the HWBB-hinged frame is investigated.The results indicate that the first mode will no longer contribute to the inner forces and the contribution from higher modes to inner forces increases after the BRBs yield.Displacement is not sensitive to higher mode effects and it is controlled by the first mode after the BRBs yield.Parameter analysis demonstrates that the displacement amplitudes are reduced with the increase in the flexural stiffness of the wall before the flexural stiffness reaches a certain value.The first three periods decrease with the increase in the rotational stiffness.With the increase in the rotational stiffness ratio,the contribution from the first mode decreases while contributions from both the second mode and third mode increase.展开更多
This paper presents the shear performance analysis of a heavy-duty universal hinged cast steel support with the largest bearing capacity. The effect of 9 parameters ( 52 specimens) ,i. e. height of the upper support,d...This paper presents the shear performance analysis of a heavy-duty universal hinged cast steel support with the largest bearing capacity. The effect of 9 parameters ( 52 specimens) ,i. e. height of the upper support,depth of the ring of the upper support,depth of the top plate of the bottom support,height of the ribs of the bottom support,depth of the ribs of the bottom support,bolt hole diameter,number of the ribs of the bowl,depth of the ribs of the bowl,and yield strength of the material,were analyzed with a 3-dimensional elastic-plastic finite element model in which the nonlinearities of geometry,material and contact were all considered. Analysis shows that height of the upper support,depth of the ring of the upper support and yield strength of the material have a great effect on the mechanical performance of the support. Height of the upper support has the largest effect on performance price ratio of the support,and the maximum effect can be up to 160% . Depth of the top plate of the bottom support,height of the ribs of the bottom support and depth of the ribs of the bottom support have a medium effect on performance price ratio of the support,and the effect is within the limit of 15% 19% .展开更多
Active vibration control for a kind of two-hinged plate is developed in this paper. A finite element model for the hinged plate integrated with distributed piezoelectric sensors and actuators is derived, including ben...Active vibration control for a kind of two-hinged plate is developed in this paper. A finite element model for the hinged plate integrated with distributed piezoelectric sensors and actuators is derived, including bending and torsional modes of vibration. In this model, the hinges are simplified as regular plate elements to facilitate operation. The state space representations for bending and torsional vibrations are obtained. Based on two low-order models of the bending and torsional motion, two H∞ robust controllers are designed for suppressing the vibrations of the bending and torsional modes, respectively. The simulation results indicate the effectiveness and feasibility of the designed H~~ controllers. The vibration magnitudes of the low-order modes can be reduced without affecting the high frequency modes.展开更多
In this paper, the theorem of structure continual variation of truss structure in the analysis of structure reliability is derived, and it is used to generate limit state function automatically. We can avoid repeated ...In this paper, the theorem of structure continual variation of truss structure in the analysis of structure reliability is derived, and it is used to generate limit state function automatically. We can avoid repeated assembly of global stiffness matrix and repeated inverse operations of the matrix caused by constant changes of structure topology. A new criterion of degenerate of the structure into mechanism is introduced. The calculation examples are satisfactory.展开更多
Study of dynamic stability phenomenon in transient systems has always created interest amongst the researchers because of its inherent non-linearities. Offshore structures subjected to wave, earthquake or wind loads o...Study of dynamic stability phenomenon in transient systems has always created interest amongst the researchers because of its inherent non-linearities. Offshore structures subjected to wave, earthquake or wind loads or a combination of these loads show non-linear transient behaviour. As oceanic waves are better modelled as stochastic process, there is a need to investigate the stochastic stability of flexible offshore structures as well. Present study has been carried out to determine seismic response of Single Hinged Articulated Tower (SHAT) under different categories of wave loads and earthquake followed by its dynamic stability analysis. Different phases of wave/earthquake loading on SHAT have been explored to investigate dynamic instabilities existing during each phase. Two dimensional phase plots have been used to identify phases of dynamic instability existing within the responses of SHAT under various conditions of loading.展开更多
To obtain high-performance tissue-adhesive hydrogel embodying excellent mechanical integrity,a supramo-lecular hydrogel patch is fabricated through in situ copolymerization of a liquid-liquid phase separation pre-curs...To obtain high-performance tissue-adhesive hydrogel embodying excellent mechanical integrity,a supramo-lecular hydrogel patch is fabricated through in situ copolymerization of a liquid-liquid phase separation pre-cursor composed of self-complementary 2-2-ureido-4-pyrimidone-based monomer and acrylic acid coupled with subsequent corporation of bioactive epigallocatechin gallate.Remarkably,the prepared supramolecular hydrogel leverages hierarchical multi-strength hydrogen-bonds hinged strategy assisted by alkyl-based hydrophobic pockets,broadening the distribution of binding strength of physical junctions,striking a canonical balance be-tween superb mechanical performance and robust adhesive capacity.Ultimately,the fabricated supramolecular hydrogel patch stands out as a high stretchability(1500%),an excellent tensile strength(2.6 MPa),a superhigh toughness(12.6 MJ m^(-3)),an instant and robust tissue adhesion strength(263.2 kPa for porcine skin),the considerable endurance under cyclic loading and reversible adhesion,a superior burst pressure tolerance(108 kPa)to those of commercially-available tissue sealants,and outstanding anti-swelling behavior.The resultant supramolecular hydrogel patch demonstrates the rapid hemorrhage control within 60 s in liver injury and efficient wound closure and healing effects with alleviated inflammation and reduced scarring in full-thickness skin incision,confirming its medical translation as a promising self-rescue tissue-adhesive patch for hemorrhage prevention and sutureless wound closure.展开更多
Kinetic facades possess aesthetic expressiveness and environmental responsiveness,aligning with the principles of low-carbon architecture.Current kinetic facades primarily rely on three-dimensional movement,which are ...Kinetic facades possess aesthetic expressiveness and environmental responsiveness,aligning with the principles of low-carbon architecture.Current kinetic facades primarily rely on three-dimensional movement,which are characterized by complex structures and distributed drives,resulting in monotonous form,low robustness,and high costs.This paper focuses on the design of two-dimensional kinetic facades,proposing a hinged tessellation generation method based on the duality principle.First,the paper discusses the value and principles of applying dual graphs in HT,and then proposes a method of generating HT by adding hinged plates.Then,the operation process for different tessellation types is elaborated upon.Finally,a conceptual design is proposed to illustrate the potential of this method on kinetic facades.The method proposed in this paper is applicable to all uniform tessellations and Voronoi tessellations,capable of generating an infinite variety of planar expandable structures with small spatial thickness,simple structures,stable movements.Additionally,these structures can be driven to expand by a single driving point,enabling continuous adjustment in response to the requirement.It has significant application value in fields such as architectural and decorative design,structural design,mechanical design,industrial product and graphic design.展开更多
The interaction between regular waves and an oscillating wave energy converter(WEC)in front of a vertical seawall is investigated using a 2D analytical model.A three-degree of freedom(DOF)WEC and a WEC hinged to the s...The interaction between regular waves and an oscillating wave energy converter(WEC)in front of a vertical seawall is investigated using a 2D analytical model.A three-degree of freedom(DOF)WEC and a WEC hinged to the seawall(constrained to pitch mode)are considered to examine the influence of the DOF of the WEC on the wave energy extraction performance.Results show that the piston-mode water resonance in the gap and the coupled WEC and water column resonant motion significantly influence the wave energy extraction efficiency.At low frequency,the case with a 3-DOF WEC has a broader high-efficiency bandwidth than that with a heaving WEC.However,3-DOF WEC exhibits worse performance at high frequencies.The frequency response of the wave energy capture width ratio(CWR)for the pitching WEC case shows a trimodal trend under the specified conditions.It showcases the best overall wave energy extraction performance in terms of the high-efficiency bandwidth.Furthermore,a parametric study indicates that the gap distance between the WEC and the seawall has tremendous effects on the CWR of both cases.As the position of the hinge point of the pitching WEC changes,the CWR at the low and high frequencies shows opposite trends.展开更多
The control criteria for structural deformation and the evaluation of operational safety performance for large-diameter shield tunnel segments are not yet clearly defined.To address this issue,a refined 3D finite elem...The control criteria for structural deformation and the evaluation of operational safety performance for large-diameter shield tunnel segments are not yet clearly defined.To address this issue,a refined 3D finite element model was established to analyze the transverse deformation response of a large-diameter segmental ring.By analyzing the stress,deformation,and crack distribution of large-diameter segments under overload conditions,the transverse deformation of the segmental ring could be divided into four stages.The main reasons for the decrease in segmental ring stiffness were found to be the extensive development of cracks and the complete formation of four plastic hinges.The deformation control value for the large-diameter shield tunnel segment is chosen as 8%o of the segment's outer diameter,representing the transverse deformation during the formation of the first semi-plastic hinge(i.e.,the first yield point)in the structure.This control value can serve as a reinforcement standard for preventing the failure of large-diameter shield tunnel segments.The flexural bearing capacity characteristic curve of segments was used to evaluate the structural strength of a large-diameter segmental ring.It was discovered that the maximum internal force combination of the segment did not exceed the segment ultimate bearing capacity curve(SUBC).However,the combination of internal force at 9°,85°,and 161°of the joints,and their symmetrical locations about the 0°-180°axis exceeded the joint ultimate bearing capacity curve(JUBC).The results indicate that the failure of the large-diameter segment lining was mainly due to insufficient joint strength,leading to an instability failure.The findings from this study can be used to develop more effective maintenance strategies for large-diameter shield tunnel segments to ensure their long-term performance.展开更多
In the realm of engineering practice,various factors such as limited availability of measurement data and complex working conditions pose significant challenges to obtaining accurate load spectra.Thus,accurately predi...In the realm of engineering practice,various factors such as limited availability of measurement data and complex working conditions pose significant challenges to obtaining accurate load spectra.Thus,accurately predicting the fatigue life of structures becomes notably arduous.This paper proposed an approach to predict the fatigue life of structure based on the optimized load spectra,which is accurately estimated by an efficient hinging hyperplane neural network(EHH-NN)model.The construction of the EHH-NN model includes initial network generation and parameter optimization.Through the combination of working conditions design,multi-body dynamics analysis and structural static mechanics analysis,the simulated load spectra of the structure are obtained.The simulated load spectra are taken as the input variables for the optimized EHH-NN model,while the measurement load spectra are used as the output variables.The prediction results of case structure indicate that the optimized EHH-NN model can achieve the high-accuracy load spectra,in comparison with support vector machine(SVM),random forest(RF)model and back propagation(BP)neural network.The error rate between the prediction values and the measurement values of the optimized EHH-NN model is 4.61%.In the Cauchy-Lorentz distribution,the absolute error data of 92%with EHH-NN model appear in the intermediate range of±1.65%.Also,the fatigue life analysis is performed for the case structure,based on the accurately predicted load spectra.The fatigue life of the case structure is calculated based on the comparison between the measured and predicted load spectra,with an accuracy of 93.56%.This research proposes the optimized EHH-NN model can more accurately reflect the measurement load spectra,enabling precise calculation of fatigue life.Additionally,the optimized EHH-NN model provides reliability assessment for industrial engineering equipment.展开更多
Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The functio...Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.展开更多
An efficient approach is proposed for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic excitations.The concentrated plastic hinges,described by the Bouc-Wen model,are as...An efficient approach is proposed for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic excitations.The concentrated plastic hinges,described by the Bouc-Wen model,are assumed to occur at the two ends of a linear-elastic beam element.The auxiliary differential equations governing the plastic rotational displacements and their corresponding hysteretic displacements are replaced with linearized differential equations.Then,the two sets of equations of motion for the original nonlinear system can be reduced to an expanded-order equivalent linearized equation of motion for equivalent linear systems.To solve the equation of motion for equivalent linear systems,the nonstationary random vibration analysis is carried out based on the explicit time-domain method with high efficiency.Finally,the proposed treatment method for initial values of equivalent parameters is investigated in conjunction with parallel computing technology,which provides a new way of obtaining the equivalent linear systems at different time instants.Based on the explicit time-domain method,the key responses of interest of the converged equivalent linear system can be calculated through dimension reduction analysis with high efficiency.Numerical examples indicate that the proposed approach has high computational efficiency,and shows good applicability to weak nonlinear and medium-intensity nonlinear systems.展开更多
In this study, the influence of confined concrete models on the response of reinforced concrete structures is investigatedat member and global system levels. The commonly encountered concrete models such as Modified K...In this study, the influence of confined concrete models on the response of reinforced concrete structures is investigatedat member and global system levels. The commonly encountered concrete models such as Modified Kent-Park, Saatçioğlu-Razvi, and Mander are considered. Two moment-resisting frames designed according to thepre-modern code are taken into consideration to reflect the example of an RC moment-resisting frame in thecurrent building stock. The building is in an earthquake-prone zone located on Z3 Soil Type. The inelasticresponse of the building frame is modelled by considering the plastic hinges formed on each beam and columnelement for different concrete classes and stirrups spacings. The models are subjected to non-linear static analyses.The differences between confined concrete models are comparatively investigated at both reinforced concretemember and system levels. Based on the results of the comparative analysis, it is revealed that the column behaviouris mostly influenced by the choice of model, due to axial loads and confinement effects, while the beams areless affected, and also it is observed that the differences exhibited in the moment-curvature response of columncross-sections do not significantly affect the overall behaviour of the global system. This highlights the critical roleof model selection relative to the concrete strength and stirrup spacing of the member.展开更多
Piezoelectric actuator has high stiffness, high frequency and infinite control precision, but a short output displacement which is often 1/1 000 of its length. In order to meet the requirements that tools feeding shou...Piezoelectric actuator has high stiffness, high frequency and infinite control precision, but a short output displacement which is often 1/1 000 of its length. In order to meet the requirements that tools feeding should be long-travel, high-frequency and high-precision in non-circular precision turning, a new one-freedom flexure hinge structure is put forward to amplify the output displacement of piezoelectric actuator. Theoretical analysis is done on the static and dynamic characteristics of the structure, differential equations are presented, and it is also verified by the finite element method. It's proved by experiments that the output displacement of the structure is 293 μm and its resonant frequency is 312 Hz.展开更多
Underground pressure is abnormal during mining of shallow coal seams under gullies. We studied gully slope movements, subject to underground mining, with physical simulation and theoretical analysis. The rules disclos...Underground pressure is abnormal during mining of shallow coal seams under gullies. We studied gully slope movements, subject to underground mining, with physical simulation and theoretical analysis. The rules disclose that the slope rock slides horizontally in response to mining in the direction of gullies and rotates reversely with the appearance of a polygon block in mining away from gullies. We focused our attention on the case of mining away from a gully. We built a mechanical model in terms of a polygon block hinged structure and investigated the variation of horizontal thrust and shear force at the hinged point in relation to the rotation angle under different fragmentations. The Sliding-Rotation instability conditions of the polygon block hinged structure are presented based on the analyses of sliding instability and rotation instability. These results can serve as a theoretical guide for roof control during mining away from gullies in a coalfield defined by gullies.展开更多
快速扩展的互联网形成了具有高维、稀疏和冗余特性的复杂网络.因此需要有效的技术从这些复杂网络数据中提取出最为重要的信息进行链接预测,以便为用户服务.本文提出一种基于AUC(Area under Curve)优化的链接预测算法.在该算法中,将AUC...快速扩展的互联网形成了具有高维、稀疏和冗余特性的复杂网络.因此需要有效的技术从这些复杂网络数据中提取出最为重要的信息进行链接预测,以便为用户服务.本文提出一种基于AUC(Area under Curve)优化的链接预测算法.在该算法中,将AUC作为优化的目标函数,将链接预测问题转化为二分分类问题.将顶点之间是否存在链接作为它所在的类的标号.通过优化AUC来进行二分分类,使用铰链函数按随机次梯度下降算法迭代更新权重矩阵.最后在一些来自不同领域的真实网络上对本算法进行了测试.实验结果表明,本算法与其他算法的结果相比可以实现更高质量的预测.展开更多
基金co-supported by the National Natural Science Foundation of China(No51775052)Beijing Natural Science Foundation(No.21C10109)+1 种基金Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment&Technology(No.FMZ202022)Beijing Municipal Key Laboratory of Space-ground Interconnection and Convergence of China。
文摘Hinged booms are widely used in astrophysics missions;however,the trajectory and deployment velocity are difficult to control because they are usually driven by springs,which limits their application in narrow spaces.Thus,a novel hinged boom is highly required to achieve motion controllability.Through an equivalent substitution between the cable drive loop and the binary link in topology,a type synthesis method for the cable-driven single-degree-of-freedom chain is proposed based on the single-open-chain(SOC)adding method.According to the configuration design,a novel cable-driven hinged boom is proposed,aiming to achieve boom synchronism.Then,to preload easily,a method that preload is applied and measured at the cable ends is adopted and the relationship between the initial preload and the target preload is deduced.By analyzing the distribution of cable tension,a new stiffness model is proposed thus a stiffness equation is obtained.Finally,the dynamic simulation analysis and zero-gravity deployment experiment of the hinged boom is carried out to verify its reliability.This research provides a new way for the type synthesis of cable-driven single-degree-of-freedom chain and a new model for analyzing cable-driven stiffness.Moreover,the novel cable-driven hinged boom obtained in this study can be well-applied in the field of aerospace.
基金The National Key Research and Development Program of China(No.2018YFC0705802)the National Natural Science Foundation of China(No.51978165)+1 种基金the Fundamental Research Funds for the Central Universities(No.3205007720)Postgraduate Research and Practice Innovation Program of Jiangsu Province(No.3205007720).
文摘To investigate the effect of higher modes on the displacement and inner forces in HWBB(hinged wall with buckling-restrained braces in base)-frame structure,distributed parameter models for both the HWBB-hinged frame structure and the HWBB-MRF(moment resisting frame)structure are built.The hinged wall is simplified as a flexural beam.BRBs(bucking-restrained braces)are simplified to a rotational spring.MRF is simplified to a shear beam.Vibration equations of distributed parameter models are derived.Natural periods,natural modes of vibration,inner forces and displacements of the distributed parameter models are derived based on the vibration equations using numerical methods.The effect of the relative stiffness ratio and the rotational stiffness ratio on the higher mode effects is investigated.For elastic structures,the global displacement and shear in MRF are predominantly controlled by the first mode,while the shear and bending moment in the wall are significantly affected by higher mode effects.The effect of the yielding of BRB on the inner forces distribution in the HWBB-hinged frame is investigated.The results indicate that the first mode will no longer contribute to the inner forces and the contribution from higher modes to inner forces increases after the BRBs yield.Displacement is not sensitive to higher mode effects and it is controlled by the first mode after the BRBs yield.Parameter analysis demonstrates that the displacement amplitudes are reduced with the increase in the flexural stiffness of the wall before the flexural stiffness reaches a certain value.The first three periods decrease with the increase in the rotational stiffness.With the increase in the rotational stiffness ratio,the contribution from the first mode decreases while contributions from both the second mode and third mode increase.
基金Sponsored by the National Natural Science Foundation of China( Grant No. 50878066)the National Key Technology R&D Program during the 11th Five-Year Plan Period of China( Grant No. 2006BAJ01B02)
文摘This paper presents the shear performance analysis of a heavy-duty universal hinged cast steel support with the largest bearing capacity. The effect of 9 parameters ( 52 specimens) ,i. e. height of the upper support,depth of the ring of the upper support,depth of the top plate of the bottom support,height of the ribs of the bottom support,depth of the ribs of the bottom support,bolt hole diameter,number of the ribs of the bowl,depth of the ribs of the bowl,and yield strength of the material,were analyzed with a 3-dimensional elastic-plastic finite element model in which the nonlinearities of geometry,material and contact were all considered. Analysis shows that height of the upper support,depth of the ring of the upper support and yield strength of the material have a great effect on the mechanical performance of the support. Height of the upper support has the largest effect on performance price ratio of the support,and the maximum effect can be up to 160% . Depth of the top plate of the bottom support,height of the ribs of the bottom support and depth of the ribs of the bottom support have a medium effect on performance price ratio of the support,and the effect is within the limit of 15% 19% .
基金Project supported by the General Projects of the National Natural Science Foundation of China(Nos.51175181 and 90505014)the Fundamental Research Funds for the Central Universities,SCUT(Nos.2012ZZ0060 and 2014ZG0019)
文摘Active vibration control for a kind of two-hinged plate is developed in this paper. A finite element model for the hinged plate integrated with distributed piezoelectric sensors and actuators is derived, including bending and torsional modes of vibration. In this model, the hinges are simplified as regular plate elements to facilitate operation. The state space representations for bending and torsional vibrations are obtained. Based on two low-order models of the bending and torsional motion, two H∞ robust controllers are designed for suppressing the vibrations of the bending and torsional modes, respectively. The simulation results indicate the effectiveness and feasibility of the designed H~~ controllers. The vibration magnitudes of the low-order modes can be reduced without affecting the high frequency modes.
文摘In this paper, the theorem of structure continual variation of truss structure in the analysis of structure reliability is derived, and it is used to generate limit state function automatically. We can avoid repeated assembly of global stiffness matrix and repeated inverse operations of the matrix caused by constant changes of structure topology. A new criterion of degenerate of the structure into mechanism is introduced. The calculation examples are satisfactory.
文摘Study of dynamic stability phenomenon in transient systems has always created interest amongst the researchers because of its inherent non-linearities. Offshore structures subjected to wave, earthquake or wind loads or a combination of these loads show non-linear transient behaviour. As oceanic waves are better modelled as stochastic process, there is a need to investigate the stochastic stability of flexible offshore structures as well. Present study has been carried out to determine seismic response of Single Hinged Articulated Tower (SHAT) under different categories of wave loads and earthquake followed by its dynamic stability analysis. Different phases of wave/earthquake loading on SHAT have been explored to investigate dynamic instabilities existing during each phase. Two dimensional phase plots have been used to identify phases of dynamic instability existing within the responses of SHAT under various conditions of loading.
基金supported by National Key Research and Develop-ment Program of China(No.2021YFE0105400)the National Nat-ural Science Foundation of China grant(No.32371404).
文摘To obtain high-performance tissue-adhesive hydrogel embodying excellent mechanical integrity,a supramo-lecular hydrogel patch is fabricated through in situ copolymerization of a liquid-liquid phase separation pre-cursor composed of self-complementary 2-2-ureido-4-pyrimidone-based monomer and acrylic acid coupled with subsequent corporation of bioactive epigallocatechin gallate.Remarkably,the prepared supramolecular hydrogel leverages hierarchical multi-strength hydrogen-bonds hinged strategy assisted by alkyl-based hydrophobic pockets,broadening the distribution of binding strength of physical junctions,striking a canonical balance be-tween superb mechanical performance and robust adhesive capacity.Ultimately,the fabricated supramolecular hydrogel patch stands out as a high stretchability(1500%),an excellent tensile strength(2.6 MPa),a superhigh toughness(12.6 MJ m^(-3)),an instant and robust tissue adhesion strength(263.2 kPa for porcine skin),the considerable endurance under cyclic loading and reversible adhesion,a superior burst pressure tolerance(108 kPa)to those of commercially-available tissue sealants,and outstanding anti-swelling behavior.The resultant supramolecular hydrogel patch demonstrates the rapid hemorrhage control within 60 s in liver injury and efficient wound closure and healing effects with alleviated inflammation and reduced scarring in full-thickness skin incision,confirming its medical translation as a promising self-rescue tissue-adhesive patch for hemorrhage prevention and sutureless wound closure.
基金supported by the National Natural Science Foundation of China(Grant No.52378043)。
文摘Kinetic facades possess aesthetic expressiveness and environmental responsiveness,aligning with the principles of low-carbon architecture.Current kinetic facades primarily rely on three-dimensional movement,which are characterized by complex structures and distributed drives,resulting in monotonous form,low robustness,and high costs.This paper focuses on the design of two-dimensional kinetic facades,proposing a hinged tessellation generation method based on the duality principle.First,the paper discusses the value and principles of applying dual graphs in HT,and then proposes a method of generating HT by adding hinged plates.Then,the operation process for different tessellation types is elaborated upon.Finally,a conceptual design is proposed to illustrate the potential of this method on kinetic facades.The method proposed in this paper is applicable to all uniform tessellations and Voronoi tessellations,capable of generating an infinite variety of planar expandable structures with small spatial thickness,simple structures,stable movements.Additionally,these structures can be driven to expand by a single driving point,enabling continuous adjustment in response to the requirement.It has significant application value in fields such as architectural and decorative design,structural design,mechanical design,industrial product and graphic design.
基金supported by the Key R&D Program of Shandong Province,China(No.2021ZLGX04)the National Natural Science Foundation of China(No.52171284)。
文摘The interaction between regular waves and an oscillating wave energy converter(WEC)in front of a vertical seawall is investigated using a 2D analytical model.A three-degree of freedom(DOF)WEC and a WEC hinged to the seawall(constrained to pitch mode)are considered to examine the influence of the DOF of the WEC on the wave energy extraction performance.Results show that the piston-mode water resonance in the gap and the coupled WEC and water column resonant motion significantly influence the wave energy extraction efficiency.At low frequency,the case with a 3-DOF WEC has a broader high-efficiency bandwidth than that with a heaving WEC.However,3-DOF WEC exhibits worse performance at high frequencies.The frequency response of the wave energy capture width ratio(CWR)for the pitching WEC case shows a trimodal trend under the specified conditions.It showcases the best overall wave energy extraction performance in terms of the high-efficiency bandwidth.Furthermore,a parametric study indicates that the gap distance between the WEC and the seawall has tremendous effects on the CWR of both cases.As the position of the hinge point of the pitching WEC changes,the CWR at the low and high frequencies shows opposite trends.
基金supported by the National Natural Science Foundation of China(Nos.52122807,52090082,and 51938005)the Youth Science and Technology Innovation Talent Project of Hunan Province(No.2021RC3043),China。
文摘The control criteria for structural deformation and the evaluation of operational safety performance for large-diameter shield tunnel segments are not yet clearly defined.To address this issue,a refined 3D finite element model was established to analyze the transverse deformation response of a large-diameter segmental ring.By analyzing the stress,deformation,and crack distribution of large-diameter segments under overload conditions,the transverse deformation of the segmental ring could be divided into four stages.The main reasons for the decrease in segmental ring stiffness were found to be the extensive development of cracks and the complete formation of four plastic hinges.The deformation control value for the large-diameter shield tunnel segment is chosen as 8%o of the segment's outer diameter,representing the transverse deformation during the formation of the first semi-plastic hinge(i.e.,the first yield point)in the structure.This control value can serve as a reinforcement standard for preventing the failure of large-diameter shield tunnel segments.The flexural bearing capacity characteristic curve of segments was used to evaluate the structural strength of a large-diameter segmental ring.It was discovered that the maximum internal force combination of the segment did not exceed the segment ultimate bearing capacity curve(SUBC).However,the combination of internal force at 9°,85°,and 161°of the joints,and their symmetrical locations about the 0°-180°axis exceeded the joint ultimate bearing capacity curve(JUBC).The results indicate that the failure of the large-diameter segment lining was mainly due to insufficient joint strength,leading to an instability failure.The findings from this study can be used to develop more effective maintenance strategies for large-diameter shield tunnel segments to ensure their long-term performance.
基金Supported by National Natural Science Foundation of China(Grant No.51805447)Natural Science Foundation of Jiangsu Higher Education of China(Grant No.22KJB460010)+2 种基金Jiangsu Provincial Innovation and Promotion Project of Forestry Science and Technology of China(Grant No.LYKJ[2023]06)Yangzhou Science and Technology Plan(City School Cooperation Project)of China(Grant No.YZ2022193)Cyan Blue Project of Yangzhou University of China。
文摘In the realm of engineering practice,various factors such as limited availability of measurement data and complex working conditions pose significant challenges to obtaining accurate load spectra.Thus,accurately predicting the fatigue life of structures becomes notably arduous.This paper proposed an approach to predict the fatigue life of structure based on the optimized load spectra,which is accurately estimated by an efficient hinging hyperplane neural network(EHH-NN)model.The construction of the EHH-NN model includes initial network generation and parameter optimization.Through the combination of working conditions design,multi-body dynamics analysis and structural static mechanics analysis,the simulated load spectra of the structure are obtained.The simulated load spectra are taken as the input variables for the optimized EHH-NN model,while the measurement load spectra are used as the output variables.The prediction results of case structure indicate that the optimized EHH-NN model can achieve the high-accuracy load spectra,in comparison with support vector machine(SVM),random forest(RF)model and back propagation(BP)neural network.The error rate between the prediction values and the measurement values of the optimized EHH-NN model is 4.61%.In the Cauchy-Lorentz distribution,the absolute error data of 92%with EHH-NN model appear in the intermediate range of±1.65%.Also,the fatigue life analysis is performed for the case structure,based on the accurately predicted load spectra.The fatigue life of the case structure is calculated based on the comparison between the measured and predicted load spectra,with an accuracy of 93.56%.This research proposes the optimized EHH-NN model can more accurately reflect the measurement load spectra,enabling precise calculation of fatigue life.Additionally,the optimized EHH-NN model provides reliability assessment for industrial engineering equipment.
文摘Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.
基金Fundamental Research Funds for the Central Universities under Grant No.2682022CX072the Research and Development Plan in Key Areas of Guangdong Province under Grant No.2020B0202010008。
文摘An efficient approach is proposed for the equivalent linearization of frame structures with plastic hinges under nonstationary seismic excitations.The concentrated plastic hinges,described by the Bouc-Wen model,are assumed to occur at the two ends of a linear-elastic beam element.The auxiliary differential equations governing the plastic rotational displacements and their corresponding hysteretic displacements are replaced with linearized differential equations.Then,the two sets of equations of motion for the original nonlinear system can be reduced to an expanded-order equivalent linearized equation of motion for equivalent linear systems.To solve the equation of motion for equivalent linear systems,the nonstationary random vibration analysis is carried out based on the explicit time-domain method with high efficiency.Finally,the proposed treatment method for initial values of equivalent parameters is investigated in conjunction with parallel computing technology,which provides a new way of obtaining the equivalent linear systems at different time instants.Based on the explicit time-domain method,the key responses of interest of the converged equivalent linear system can be calculated through dimension reduction analysis with high efficiency.Numerical examples indicate that the proposed approach has high computational efficiency,and shows good applicability to weak nonlinear and medium-intensity nonlinear systems.
文摘In this study, the influence of confined concrete models on the response of reinforced concrete structures is investigatedat member and global system levels. The commonly encountered concrete models such as Modified Kent-Park, Saatçioğlu-Razvi, and Mander are considered. Two moment-resisting frames designed according to thepre-modern code are taken into consideration to reflect the example of an RC moment-resisting frame in thecurrent building stock. The building is in an earthquake-prone zone located on Z3 Soil Type. The inelasticresponse of the building frame is modelled by considering the plastic hinges formed on each beam and columnelement for different concrete classes and stirrups spacings. The models are subjected to non-linear static analyses.The differences between confined concrete models are comparatively investigated at both reinforced concretemember and system levels. Based on the results of the comparative analysis, it is revealed that the column behaviouris mostly influenced by the choice of model, due to axial loads and confinement effects, while the beams areless affected, and also it is observed that the differences exhibited in the moment-curvature response of columncross-sections do not significantly affect the overall behaviour of the global system. This highlights the critical roleof model selection relative to the concrete strength and stirrup spacing of the member.
文摘Piezoelectric actuator has high stiffness, high frequency and infinite control precision, but a short output displacement which is often 1/1 000 of its length. In order to meet the requirements that tools feeding should be long-travel, high-frequency and high-precision in non-circular precision turning, a new one-freedom flexure hinge structure is put forward to amplify the output displacement of piezoelectric actuator. Theoretical analysis is done on the static and dynamic characteristics of the structure, differential equations are presented, and it is also verified by the finite element method. It's proved by experiments that the output displacement of the structure is 293 μm and its resonant frequency is 312 Hz.
基金Financial support for this work, provided by the Research Fund of the Fundamental Research Funds for the Central Universities of China University of Mining & Technology (No. 2010ZDP02B02)the State Key Laboratory of Coal Resources and Mine Safety (No. SKLCRSM08X2)+1 种基金the Jiangsu "333" High Qualified Talents, the National Natural Science Foundation of China (Nos. 50904063 and 51004101)the Scientific Research Foundation of China University of Mining & Technology (Nos. 2008A003 and 2009A001)
文摘Underground pressure is abnormal during mining of shallow coal seams under gullies. We studied gully slope movements, subject to underground mining, with physical simulation and theoretical analysis. The rules disclose that the slope rock slides horizontally in response to mining in the direction of gullies and rotates reversely with the appearance of a polygon block in mining away from gullies. We focused our attention on the case of mining away from a gully. We built a mechanical model in terms of a polygon block hinged structure and investigated the variation of horizontal thrust and shear force at the hinged point in relation to the rotation angle under different fragmentations. The Sliding-Rotation instability conditions of the polygon block hinged structure are presented based on the analyses of sliding instability and rotation instability. These results can serve as a theoretical guide for roof control during mining away from gullies in a coalfield defined by gullies.
文摘快速扩展的互联网形成了具有高维、稀疏和冗余特性的复杂网络.因此需要有效的技术从这些复杂网络数据中提取出最为重要的信息进行链接预测,以便为用户服务.本文提出一种基于AUC(Area under Curve)优化的链接预测算法.在该算法中,将AUC作为优化的目标函数,将链接预测问题转化为二分分类问题.将顶点之间是否存在链接作为它所在的类的标号.通过优化AUC来进行二分分类,使用铰链函数按随机次梯度下降算法迭代更新权重矩阵.最后在一些来自不同领域的真实网络上对本算法进行了测试.实验结果表明,本算法与其他算法的结果相比可以实现更高质量的预测.
