This paper proposes a multiscale isogeometric topology optimization(ITO)method where the configuration and layout of microstructures are optimized simultaneously.At micro scale,a shape deformation method is presented ...This paper proposes a multiscale isogeometric topology optimization(ITO)method where the configuration and layout of microstructures are optimized simultaneously.At micro scale,a shape deformation method is presented to transform a prototype microstructure(PM)for obtaining a series of graded microstructures(GMs),where microstructural skeleton based on the level set framework is applied to retain more topology features and improve the connectability.For the macro scale calculation,the effective mechanical properties can be estimated by means of the numerical homogenization method.By adopting identical non-uniform rational basis splines(NURBS)as basis functions for both parameterized level set model and isogeometric calculation model,the isogeometric analysis(IGA)is integrated into the level set method,which contributes to improving the accuracy and efficiency.Numerical examples demonstrate that,the proposed method is effective in improving the performance and manufacturability.展开更多
This paper presents an effective fiber angle optimization method for two and multi-layered variable stiffness composites.A gradient-based fiber angle optimization method is developed based on isogeometric analysis(IGA...This paper presents an effective fiber angle optimization method for two and multi-layered variable stiffness composites.A gradient-based fiber angle optimization method is developed based on isogeometric analysis(IGA).Firstly,the element densities and fiber angles for two and multi-layered composites are synchronously optimized using an extended Bi-layered continuous fiber angle optimization method(XBi-CFAO).The densities and fiber angles in the base layer are attached to the control points.The structure response and sensitivity analysis are accomplished using the non-uniform rational B-spline(NURBS)based IGA.By the benefit of the B-spline space,this method is free from checkerboards,and no additional filtering is needed to smooth the sensitivity numbers.Then the curved fiber paths are generated using the streamline method and the discontinuous fiber paths are smoothed using a partitioned selection process.The proposed method in the paper can alleviate the phenomenon of fiber discontinuity,enhance information retention for the optimized fiber angles of the singular points and save calculating resources effectively.展开更多
This paper presents a topology optimization method for variable stiffness composite panels with varying fiber orientation and curvilinear fiber path.Non-uniform rational B-Splines(NURBS)based Isogeometric analysis(IGA...This paper presents a topology optimization method for variable stiffness composite panels with varying fiber orientation and curvilinear fiber path.Non-uniform rational B-Splines(NURBS)based Isogeometric analysis(IGA)is utilized for the numerical computation of the general minimum compliance problem.The sensitivity analysis of the structure compliance function for the density and bi-layer orientation is conducted.The bi-layer fiber paths in the design domain are generated using streamline method and updated by divided pieces reselection method after the optimization process.Several common examples are tested to demonstrate the effectiveness of the method.The results show that the proposed method can generate more manufacturable fiber paths than some typical topology optimization methods.展开更多
We numerically investigate the mid-infrared(MIR)supercontinuum(SC)and SC-based optical frequency comb(OFC)generations when the three optical modes(LP_(01),LP_(02),and LP_(12))are considered in a multimode tellurite ph...We numerically investigate the mid-infrared(MIR)supercontinuum(SC)and SC-based optical frequency comb(OFC)generations when the three optical modes(LP_(01),LP_(02),and LP_(12))are considered in a multimode tellurite photonic crystal fiber(MM-TPCF).The geometrical parameters of the MM-TPCF are optimized to support the multimode propagation and obtain the desired dispersion characteristics of the considered three optical modes.When the pump pulse with center wavelengthλ=2.5μm,width T=80 fs,and peak power P=18 kW is coupled into the anomalous dispersion region of the LP_(01),LP_(02),and LP_(12)modes of the MM-TPCF,the-40-dB bandwidth of the generated MIR SCs can be up to 2.56,1.39,and 1.12 octaves,respectively,along with good coherence.Moreover,the nonlinear dynamics of the generated SCs are analyzed.Finally,the MIR SCs-based OFCs are demonstrated when a train of 50 pulses at 1-GHz repetition rate is used as the pump source and launched into the MM-TPCF.展开更多
The superposition effect of river floods and urban waterlogging is becoming more common in urbanized watersheds.A quantitative assessment method was proposed based on the copula function and hydrological and hydrodyna...The superposition effect of river floods and urban waterlogging is becoming more common in urbanized watersheds.A quantitative assessment method was proposed based on the copula function and hydrological and hydrodynamic models to explore the exacerbating effect on urban inundation.The suggested method was applied to construct the joint distribution pattern of river flood and heavy rainfall in a typical urbanized watershed,the North Canal Basin in Tongzhou District,Beijing.An integrated model was constructed to simulate the hydrological and hydrodynamic processes during river floods and urban waterlogging.The 38 different combination patterns of rainfall and river flood scenarios were analysed,and the results showed a significant exacerbating effect on urban inundation when a river flood encounters heavy rainfall.The insight factor analysis showed that the water depth was more sensitive to river flooding changes than to rainfall.Taking the 50-year return period as an example,compared with scenarios with only rainfall or river flood,the maximum water depth under the superimposed scenarios increased by 1.7 and 0.2 m,respectively.The simulation results indicated that the simultaneous occurrence of river floods and heavy rainfall would have a superimposed amplification effect on urban inundation risk.展开更多
Attention deficit disorder is a frequently observed symptom in individuals with autism spectrum disorder(ASD).This condition can present significant obstacles for those affected,manifesting in challenges such as susta...Attention deficit disorder is a frequently observed symptom in individuals with autism spectrum disorder(ASD).This condition can present significant obstacles for those affected,manifesting in challenges such as sustained focus,task completion,and the management of distractions.These issues can impede learning,social interactions,and daily functioning.This complexity of symptoms underscores the need for tailored approaches in both educational and therapeutic settings to support individuals with ASD effectively.In this study,we have expanded upon our initial virtual reality(VR)prototype,originally created for attention therapy,to conduct a detailed statistical analysis.Our objective was to precisely identify and measure any significant differences in attention-related outcomes between sessions and groups.Our study found that heart rate(HR)and electrodermal activity(EDA)were more responsive to attention shifts than temperature.The‘Noise’and‘Score’strategies significantly affected eye openness,with the ASD group showing more responsiveness.The control group had smaller pupil sizes,and the ASD group’s pupil size increased notably when switching strategies in Session 1.Distraction log data showed that both‘Noise’and‘Object Opacity’strategies influenced attention patterns,with the‘Red Vignette’strategy showing a significant effect only in the ASD group.The responsiveness of HR and EDA to attention shifts and the changes in pupil size could serve as valuable physiological markers to monitor and guide these interventions.These findings further support evidence that VR has positive implications for helping those with ASD,allowing for more tailored personalized interventions with meaningful impact.展开更多
We firstly report a 2-μm all-fiber nonlinear pulse compressor based on two pieces of normal dispersion fiber(NDF),which enables a high-power scaling ability of watt-level and a high pulse compression ratio of 13.7.Wi...We firstly report a 2-μm all-fiber nonlinear pulse compressor based on two pieces of normal dispersion fiber(NDF),which enables a high-power scaling ability of watt-level and a high pulse compression ratio of 13.7.With the NDFbased all-fiber nonlinear pulse compressor,the 450-fs laser pulses with a repetition rate of 101.4 MHz are compressed to 35.1 fs,corresponding to a 5.2 optical oscillation cycle at the 2-μm wavelength region.The output average power reaches 1.28 W,which is believed to be the highest value never achieved from the previous 2-μm all-fiber nonlinear pulse compressors with a high pulse repetition rate above 100 MHz.The dynamic evolution of the ultrafast pulse inside the all-fiber nonlinear pulse compressor is numerically analyzed,matching well with the experimental results.展开更多
Multimode nonlinear optics is used to overcome a long-standing limitation of fiber optics,tightly phase locking several spatial modes and enabling the coherent transport of a wave packet through a multimode fiber.A si...Multimode nonlinear optics is used to overcome a long-standing limitation of fiber optics,tightly phase locking several spatial modes and enabling the coherent transport of a wave packet through a multimode fiber.A similar problem is encountered in the temporal compression of multimillijoule pulses to few-cycle duration in hollow gas-filled fibers.Scaling the fiber length to up to 6 m,hollow fibers have recently reached 1 TW of peak power.Despite the remarkable utility of the hollow fiber compressor and its widespread application,however,no analytical model exists to enable insight into the scaling behavior of maximum compressibility and peak power.Here we extend a recently introduced formalism for describing mode locking to the analog scenario of locking spatial fiber modes together.Our formalism unveils the coexistence of two soliton branches for anomalous modal dispersion and indicates the formation of stable spatiotemporal light bullets that would be unstable in free space,similar to the temporal cage solitons in mode-locking theory.Our model enables deeper understanding of the physical processes behind the formation of such light bullets and predicts the existence of multimode solitons in a much wider range of fiber types than previously considered possible.展开更多
基金National Key R&D Program of China(2018YFB1700803,2018YFB1700804).
文摘This paper proposes a multiscale isogeometric topology optimization(ITO)method where the configuration and layout of microstructures are optimized simultaneously.At micro scale,a shape deformation method is presented to transform a prototype microstructure(PM)for obtaining a series of graded microstructures(GMs),where microstructural skeleton based on the level set framework is applied to retain more topology features and improve the connectability.For the macro scale calculation,the effective mechanical properties can be estimated by means of the numerical homogenization method.By adopting identical non-uniform rational basis splines(NURBS)as basis functions for both parameterized level set model and isogeometric calculation model,the isogeometric analysis(IGA)is integrated into the level set method,which contributes to improving the accuracy and efficiency.Numerical examples demonstrate that,the proposed method is effective in improving the performance and manufacturability.
基金This research work is supported by the National Key R&D Project of China(Grant Nos.2018YFB1700803 and 2018YFB1700804)managed by Qifu Wang.These supports are gratefully acknowledged.
文摘This paper presents an effective fiber angle optimization method for two and multi-layered variable stiffness composites.A gradient-based fiber angle optimization method is developed based on isogeometric analysis(IGA).Firstly,the element densities and fiber angles for two and multi-layered composites are synchronously optimized using an extended Bi-layered continuous fiber angle optimization method(XBi-CFAO).The densities and fiber angles in the base layer are attached to the control points.The structure response and sensitivity analysis are accomplished using the non-uniform rational B-spline(NURBS)based IGA.By the benefit of the B-spline space,this method is free from checkerboards,and no additional filtering is needed to smooth the sensitivity numbers.Then the curved fiber paths are generated using the streamline method and the discontinuous fiber paths are smoothed using a partitioned selection process.The proposed method in the paper can alleviate the phenomenon of fiber discontinuity,enhance information retention for the optimized fiber angles of the singular points and save calculating resources effectively.
基金supported by the National Key R&D Project of China(Grant No.2018YFB1700803,and Grant No.2018YFB1700804)received by Qifu Wang.
文摘This paper presents a topology optimization method for variable stiffness composite panels with varying fiber orientation and curvilinear fiber path.Non-uniform rational B-Splines(NURBS)based Isogeometric analysis(IGA)is utilized for the numerical computation of the general minimum compliance problem.The sensitivity analysis of the structure compliance function for the density and bi-layer orientation is conducted.The bi-layer fiber paths in the design domain are generated using streamline method and updated by divided pieces reselection method after the optimization process.Several common examples are tested to demonstrate the effectiveness of the method.The results show that the proposed method can generate more manufacturable fiber paths than some typical topology optimization methods.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074331,61875238,and 61971373)the Natural Science Foundation of Hebei Province,China(Grant Nos.F2021203002,F2019203549,and F2020203050)the Science and Technology Support Projects of Research and Development Plans of Qinhuangdao City(Grant No.202004A001).
文摘We numerically investigate the mid-infrared(MIR)supercontinuum(SC)and SC-based optical frequency comb(OFC)generations when the three optical modes(LP_(01),LP_(02),and LP_(12))are considered in a multimode tellurite photonic crystal fiber(MM-TPCF).The geometrical parameters of the MM-TPCF are optimized to support the multimode propagation and obtain the desired dispersion characteristics of the considered three optical modes.When the pump pulse with center wavelengthλ=2.5μm,width T=80 fs,and peak power P=18 kW is coupled into the anomalous dispersion region of the LP_(01),LP_(02),and LP_(12)modes of the MM-TPCF,the-40-dB bandwidth of the generated MIR SCs can be up to 2.56,1.39,and 1.12 octaves,respectively,along with good coherence.Moreover,the nonlinear dynamics of the generated SCs are analyzed.Finally,the MIR SCs-based OFCs are demonstrated when a train of 50 pulses at 1-GHz repetition rate is used as the pump source and launched into the MM-TPCF.
基金supported by the Chinese National Key Research and Development Program(Grant No.2022YFC3090600)the National Natural Science Foundation of China(Grant No.52192671)+2 种基金the IWHR Research&Development Support Program(Grant No.WR110145B0022022)the Research Fund of the State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(Grant No.SKL2022TS11)the Open Research Fund of Key Laboratory of River Basin Digital Twinning of Ministry of Water Resources。
文摘The superposition effect of river floods and urban waterlogging is becoming more common in urbanized watersheds.A quantitative assessment method was proposed based on the copula function and hydrological and hydrodynamic models to explore the exacerbating effect on urban inundation.The suggested method was applied to construct the joint distribution pattern of river flood and heavy rainfall in a typical urbanized watershed,the North Canal Basin in Tongzhou District,Beijing.An integrated model was constructed to simulate the hydrological and hydrodynamic processes during river floods and urban waterlogging.The 38 different combination patterns of rainfall and river flood scenarios were analysed,and the results showed a significant exacerbating effect on urban inundation when a river flood encounters heavy rainfall.The insight factor analysis showed that the water depth was more sensitive to river flooding changes than to rainfall.Taking the 50-year return period as an example,compared with scenarios with only rainfall or river flood,the maximum water depth under the superimposed scenarios increased by 1.7 and 0.2 m,respectively.The simulation results indicated that the simultaneous occurrence of river floods and heavy rainfall would have a superimposed amplification effect on urban inundation risk.
基金supported by the US National Science Foundation(2244221 and 2315595).
文摘Attention deficit disorder is a frequently observed symptom in individuals with autism spectrum disorder(ASD).This condition can present significant obstacles for those affected,manifesting in challenges such as sustained focus,task completion,and the management of distractions.These issues can impede learning,social interactions,and daily functioning.This complexity of symptoms underscores the need for tailored approaches in both educational and therapeutic settings to support individuals with ASD effectively.In this study,we have expanded upon our initial virtual reality(VR)prototype,originally created for attention therapy,to conduct a detailed statistical analysis.Our objective was to precisely identify and measure any significant differences in attention-related outcomes between sessions and groups.Our study found that heart rate(HR)and electrodermal activity(EDA)were more responsive to attention shifts than temperature.The‘Noise’and‘Score’strategies significantly affected eye openness,with the ASD group showing more responsiveness.The control group had smaller pupil sizes,and the ASD group’s pupil size increased notably when switching strategies in Session 1.Distraction log data showed that both‘Noise’and‘Object Opacity’strategies influenced attention patterns,with the‘Red Vignette’strategy showing a significant effect only in the ASD group.The responsiveness of HR and EDA to attention shifts and the changes in pupil size could serve as valuable physiological markers to monitor and guide these interventions.These findings further support evidence that VR has positive implications for helping those with ASD,allowing for more tailored personalized interventions with meaningful impact.
基金supported by the National Natural Science Foundation of China(Nos.62005144,61775119,and 62175128)the Natural Science Foundation of Shandong Province(No.ZR2020QF096)+2 种基金the Qilu Young Scholar Program of Shandong Universitythe Taishan Scholar Foundation of Shandong Province(No.tsqn201812010)the High-level Talent Cultivation Funds of the State Key Laboratory of Crystal Materials of Shandong University
文摘We firstly report a 2-μm all-fiber nonlinear pulse compressor based on two pieces of normal dispersion fiber(NDF),which enables a high-power scaling ability of watt-level and a high pulse compression ratio of 13.7.With the NDFbased all-fiber nonlinear pulse compressor,the 450-fs laser pulses with a repetition rate of 101.4 MHz are compressed to 35.1 fs,corresponding to a 5.2 optical oscillation cycle at the 2-μm wavelength region.The output average power reaches 1.28 W,which is believed to be the highest value never achieved from the previous 2-μm all-fiber nonlinear pulse compressors with a high pulse repetition rate above 100 MHz.The dynamic evolution of the ultrafast pulse inside the all-fiber nonlinear pulse compressor is numerically analyzed,matching well with the experimental results.
基金Fundamental Research Funds for the Central Universities (00007475)CSC-DAAD (57460082)。
文摘Multimode nonlinear optics is used to overcome a long-standing limitation of fiber optics,tightly phase locking several spatial modes and enabling the coherent transport of a wave packet through a multimode fiber.A similar problem is encountered in the temporal compression of multimillijoule pulses to few-cycle duration in hollow gas-filled fibers.Scaling the fiber length to up to 6 m,hollow fibers have recently reached 1 TW of peak power.Despite the remarkable utility of the hollow fiber compressor and its widespread application,however,no analytical model exists to enable insight into the scaling behavior of maximum compressibility and peak power.Here we extend a recently introduced formalism for describing mode locking to the analog scenario of locking spatial fiber modes together.Our formalism unveils the coexistence of two soliton branches for anomalous modal dispersion and indicates the formation of stable spatiotemporal light bullets that would be unstable in free space,similar to the temporal cage solitons in mode-locking theory.Our model enables deeper understanding of the physical processes behind the formation of such light bullets and predicts the existence of multimode solitons in a much wider range of fiber types than previously considered possible.
