This paper tackles the formation-containment control problem of fixed-wing unmanned aerial vehicle(UAV)swarm with model uncertainties for dynamic target tracking in three-dimensional space in the faulty case of UAVs’...This paper tackles the formation-containment control problem of fixed-wing unmanned aerial vehicle(UAV)swarm with model uncertainties for dynamic target tracking in three-dimensional space in the faulty case of UAVs’actuator and sensor.The fixed-wing UAV swarm under consideration is organized as a“multi-leader-multi-follower”structure,in which only several leaders can obtain the dynamic target information while others only receive the neighbors’information through the communication network.To simultaneously realize the formation,containment,and dynamic target tracking,a two-layer control framework is adopted to decouple the problem into two subproblems:reference trajectory generation and trajectory tracking.In the upper layer,a distributed finite-time estimator(DFTE)is proposed to generate each UAV’s reference trajectory in accordance with the control objective.Subsequently,a distributed composite robust fault-tolerant trajectory tracking controller is developed in the lower layer,where a novel adaptive extended super-twisting(AESTW)algorithm with a finite-time extended state observer(FTESO)is involved in solving the robust trajectory tracking control problem under model uncertainties,actuator,and sensor faults.The proposed controller simultaneously guarantees rapidness and enhances the system’s robustness with fewer chattering effects.Finally,corresponding simulations are carried out to demonstrate the effectiveness and competitiveness of the proposed two-layer fault-tolerant cooperative control scheme.展开更多
This work uses refined first-order shear theory to analyze the free vibration and transient responses of double-curved sandwich two-layer shells made of auxetic honeycomb core and laminated three-phase polymer/GNP/fib...This work uses refined first-order shear theory to analyze the free vibration and transient responses of double-curved sandwich two-layer shells made of auxetic honeycomb core and laminated three-phase polymer/GNP/fiber surface subjected to the blast load.Each of the two layers that make up the double-curved shell structure is made up of an auxetic honeycomb core and two laminated sheets of three-phase polymer/GNP/fiber.The exterior is supported by a Kerr elastic foundation with three characteristics.The key innovation of the proposed theory is that the transverse shear stresses are zero at two free surfaces of each layer.In contrast to previous first-order shear deformation theories,no shear correction factor is required.Navier's exact solution was used to treat the double-curved shell problem with a single title boundary,while the finite element technique and an eight-node quadrilateral were used to address the other boundary requirements.To ensure the accuracy of these results,a thorough comparison technique is employed in conjunction with credible statements.The problem model's edge cases allow for this kind of analysis.The study's findings may be used in the post-construction evaluation of military and civil works structures for their ability to sustain explosive loads.In addition,this is also an important basis for the calculation and design of shell structures made of smart materials when subjected to shock waves or explosive loads.展开更多
A patch-based method for detecting vehicle logos using prior knowledge is proposed.By representing the coarse region of the logo with the weight matrix of patch intensity and position,the proposed method is robust to ...A patch-based method for detecting vehicle logos using prior knowledge is proposed.By representing the coarse region of the logo with the weight matrix of patch intensity and position,the proposed method is robust to bad and complex environmental conditions.The bounding-box of the logo is extracted by a thershloding approach.Experimental results show that 93.58% location accuracy is achieved with 1100 images under various environmental conditions,indicating that the proposed method is effective and suitable for the location of vehicle logo in practical applications.展开更多
The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate.This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy ...The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate.This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy woven laminates.The specimens of[0°/45°/45°/0°]laminates were repaired with adhesively bonded two-ply[45°]2external patches.Three different cases of drilled specimens were produced with different hole arrangements viz.specimens with single central hole(SH),with two holes aligned along the longitudinal axis(LH)and with two holes along transverse axis(TH).The two-hole specimens were repaired with two different types,i.e.single large patches(SP)and with the two smaller patches(DP)of combined bonding area equal to the single large patches.Digital image correlation(DIC)was employed to capture strain contours.The results reveal the difference in the load transfer through the patches depending upon the arrangement of holes.The TH repaired specimen exhibit significant load recovery(SP-32.75%,DP-34.62%)while the LH specimens result in very marginal(SP-6.11%,DP-4.10%)recovery compared to their drilled case.The TH specimen failed by crack growing through both the holes beneath the patch,while the LH specimens failed by the failure through only one hole.The use of single large patch over multiple holes and multiple small patches individually over each hole has no significant influence on load recovery.展开更多
In recent years,the field of mechanomaterials has emerged at the interface of mechanics,materials science,biology,medicine and data science,where materials are proactively designed or programmed to achieve targeted fu...In recent years,the field of mechanomaterials has emerged at the interface of mechanics,materials science,biology,medicine and data science,where materials are proactively designed or programmed to achieve targeted functionalities by leveraging the fundamental mechanics principles and force-geometry-property relationships.In the biological context,one may likewise introduce mechanobiomaterials as a field with the following goals:(1)proactive design or programming of materials for precisely mediating biomechanical environment of living systems for tissue repair/restoration;(2)proactive control/programming of living systems themselves by an external field via force-structure-function relationships.Here,we will discuss an example of research in mechanobiomaterials on using mechanics to guide the design of acellular epicardial patches for the treatment of myocardial infarction.This technology aims to employ a biocompatible material patch to help reverse left ventricular remodeling and restore heart function after myocardial infarction by increasing the mechanical integrity of damaged heart tissues.However,its application is currently limited by widely scattered therapeutic efficacy.Here,we develop a biomechanics-based simulation platform that allows us to test,design and optimize the performance of an epicardial patch.We show that the widely scattered therapeutic efficacy of this technology can be attributed to a“pre-strain sensitivity”caused by attaching an elastic patch to a dynamically beating heart.To mitigate this challenge,we introduce a viscoelastic epicardial patch,designed at the so-called‘gel point’of the material,that effectively accommodates the cyclic deformation of the myocardium.This then leads to the fabrication and experimentally validated epicardial patch that outperforms all existing ones in restoring heart function after both acute and subacute myocardial infarction in rats.Our study also demonstrates the potential of employing viscoelastic interfaces for better integration of synthetic materials with biological tissues.展开更多
Objective:Drug-loaded mucoadhesive silk fibroin(SF)microneedle patch can overcome the limitations of low bioavailability and significant pain associated with traditional treatment methods,such as topical application o...Objective:Drug-loaded mucoadhesive silk fibroin(SF)microneedle patch can overcome the limitations of low bioavailability and significant pain associated with traditional treatment methods,such as topical application or injection of triamcinolone for oral submucous fibrosis(OSF).However,these systems release the drug too quickly,failing to meet the clinical requirements.This study aims to construct a mucoadhesive SF microneedle patch pre-assembled with silk fibroin nanospheres(SFN)and explore its ability to sustain the release of triamcinolone in the treatment of OSF.Methods:SFN was pre-assembled via precipitation reaction and characterized by scanning electron microscope(SEM)for the morphology.The particle size andζ-potential were measured by dynamic light scattering(DLS).Triamcinolone was loaded onto SFN using a diffusional post-loading method.The effective loading of triamcinolone was confirmed using Fourier-transform infrared spectroscopy(FTIR).The concentration of unloaded triamcinolone was quantified by high-performance liquid chromatography.Drug encapsulation efficiency and loading capacity of SFN were then calculated to determine the optimal amount of drug loading.The SFN suspension was pre-mixed with SF solution to prepare the microneedle under-layer.The microneedle morphology was observed by SEM.Compression mechanical tests were performed to evaluate the fracture force of microneedles at different nanosphere contents(5%,10%,and 20%),determining the optimal pre-mixing ratio.Ex-vivo mouse oral mucosa permeation studies were performed to ascertain the insertion depth of the microneedles via histological sections.The adhesive top layer was synthesized using SF and tannic acid,with FTIR confirming its successful synthesis.Its viscoelasticity was characterized by a rheometer,and differential scanning calorimetry analyzed thermal properties.Tensile tests evaluated the interfacial bonding strength between the adhesive layer and microneedle base to ensure no detachment during use.Adhesion to wet oral mucosal tissues was tested and compared to commercial oral patches.Under the optimized conditions,the double-layered mucoadhesive microneedle patch with pre-assembled nanospheres was prepared.Its cell compatibility was evaluated by cell counting kit-8(CCK-8),live/dead staining,and phalloidin staining after co culturing with fibroblasts.The drug release experiment was conducted to demonstrate its sustained release efficacy.Results:SFN(mean diameter 46.25 nm)was successfully prepared.The maximum drug encapsulation efficiency was(63.88±1.09)%(corresponding loading capacity of SFN was(27.41±3.06)%when the weight ratio of triamcinolone/SFN was 0.5.The corporation of SFN did not affect microneedle morphology.The mechanical properties of microneedles decreased with increasing nanosphere amount.Only the fracture force of the group with 5%SFN[(0.07±0.01)N/needle]exceeded the minimum force required for mucosal penetration,thus selected as the optimal pre-mixing ratio.Histological sections confirmed that the SFN microneedles could penetrate the epithelial layer and deliver drugs to OSF affected areas.Adhesion strength between the microneedle base and top layer was(94.8±6.89)kPa,confirming strong bonding with no detachment during use.The wet adhesive strength of the double-layered mucoadhesive microneedle patch[(41.28±7.43)kPa]was significantly enhanced compared to commercial oral patches(4.5 kPa,P<0.01).CCK-8 and live/dead staining results confirmed no significant cytotoxicity.Drug release experiment showed the double-layered mucoadhesive microneedle patch with pre-assembled SFN enabled sustained release time of triamcinolone from 4 days to 14 days.Conclusion:Pre-assembling nanospheres in mucoadhesive SF microneedle patches can extend triamcinolone release time,meeting clinical requirements for sustained drug delivery.展开更多
A new multi-species particle swarm optimization with a two-level hierarchical topology and the orthogonal learning strategy(OMSPSO) is proposed, which enhances the global search ability of particles and increases thei...A new multi-species particle swarm optimization with a two-level hierarchical topology and the orthogonal learning strategy(OMSPSO) is proposed, which enhances the global search ability of particles and increases their convergence rates. The numerical results on 10 benchmark functions demonstrated the effectiveness of our proposed algorithm. Then, the proposed algorithm is presented to design a butterfly-shaped microstrip patch antenna. Combined with the HFSS solver, a butterfly-shaped patch antenna with a bandwidth of about 40.1% is designed by using the proposed OMSPSO. The return loss of the butterfly-shaped antenna is greater than 10 d B between 4.15 and 6.36 GHz. The antenna can serve simultaneously for the high-speed wireless computer networks(5.15–5.35 GHz) and the RFID systems(5.8 GHz).展开更多
基金the National Natural Science Foundation of China(61933010)the Natural Science Basic Research Plan in Shaanxi Province of China(2023-JC-QN-0733).
文摘This paper tackles the formation-containment control problem of fixed-wing unmanned aerial vehicle(UAV)swarm with model uncertainties for dynamic target tracking in three-dimensional space in the faulty case of UAVs’actuator and sensor.The fixed-wing UAV swarm under consideration is organized as a“multi-leader-multi-follower”structure,in which only several leaders can obtain the dynamic target information while others only receive the neighbors’information through the communication network.To simultaneously realize the formation,containment,and dynamic target tracking,a two-layer control framework is adopted to decouple the problem into two subproblems:reference trajectory generation and trajectory tracking.In the upper layer,a distributed finite-time estimator(DFTE)is proposed to generate each UAV’s reference trajectory in accordance with the control objective.Subsequently,a distributed composite robust fault-tolerant trajectory tracking controller is developed in the lower layer,where a novel adaptive extended super-twisting(AESTW)algorithm with a finite-time extended state observer(FTESO)is involved in solving the robust trajectory tracking control problem under model uncertainties,actuator,and sensor faults.The proposed controller simultaneously guarantees rapidness and enhances the system’s robustness with fewer chattering effects.Finally,corresponding simulations are carried out to demonstrate the effectiveness and competitiveness of the proposed two-layer fault-tolerant cooperative control scheme.
文摘This work uses refined first-order shear theory to analyze the free vibration and transient responses of double-curved sandwich two-layer shells made of auxetic honeycomb core and laminated three-phase polymer/GNP/fiber surface subjected to the blast load.Each of the two layers that make up the double-curved shell structure is made up of an auxetic honeycomb core and two laminated sheets of three-phase polymer/GNP/fiber.The exterior is supported by a Kerr elastic foundation with three characteristics.The key innovation of the proposed theory is that the transverse shear stresses are zero at two free surfaces of each layer.In contrast to previous first-order shear deformation theories,no shear correction factor is required.Navier's exact solution was used to treat the double-curved shell problem with a single title boundary,while the finite element technique and an eight-node quadrilateral were used to address the other boundary requirements.To ensure the accuracy of these results,a thorough comparison technique is employed in conjunction with credible statements.The problem model's edge cases allow for this kind of analysis.The study's findings may be used in the post-construction evaluation of military and civil works structures for their ability to sustain explosive loads.In addition,this is also an important basis for the calculation and design of shell structures made of smart materials when subjected to shock waves or explosive loads.
文摘A patch-based method for detecting vehicle logos using prior knowledge is proposed.By representing the coarse region of the logo with the weight matrix of patch intensity and position,the proposed method is robust to bad and complex environmental conditions.The bounding-box of the logo is extracted by a thershloding approach.Experimental results show that 93.58% location accuracy is achieved with 1100 images under various environmental conditions,indicating that the proposed method is effective and suitable for the location of vehicle logo in practical applications.
基金the financial support by the Council of Scientific&Industrial Research (CSIR)-Research Scheme (22/0809/2019-EMR-Ⅱ)
文摘The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate.This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy woven laminates.The specimens of[0°/45°/45°/0°]laminates were repaired with adhesively bonded two-ply[45°]2external patches.Three different cases of drilled specimens were produced with different hole arrangements viz.specimens with single central hole(SH),with two holes aligned along the longitudinal axis(LH)and with two holes along transverse axis(TH).The two-hole specimens were repaired with two different types,i.e.single large patches(SP)and with the two smaller patches(DP)of combined bonding area equal to the single large patches.Digital image correlation(DIC)was employed to capture strain contours.The results reveal the difference in the load transfer through the patches depending upon the arrangement of holes.The TH repaired specimen exhibit significant load recovery(SP-32.75%,DP-34.62%)while the LH specimens result in very marginal(SP-6.11%,DP-4.10%)recovery compared to their drilled case.The TH specimen failed by crack growing through both the holes beneath the patch,while the LH specimens failed by the failure through only one hole.The use of single large patch over multiple holes and multiple small patches individually over each hole has no significant influence on load recovery.
文摘In recent years,the field of mechanomaterials has emerged at the interface of mechanics,materials science,biology,medicine and data science,where materials are proactively designed or programmed to achieve targeted functionalities by leveraging the fundamental mechanics principles and force-geometry-property relationships.In the biological context,one may likewise introduce mechanobiomaterials as a field with the following goals:(1)proactive design or programming of materials for precisely mediating biomechanical environment of living systems for tissue repair/restoration;(2)proactive control/programming of living systems themselves by an external field via force-structure-function relationships.Here,we will discuss an example of research in mechanobiomaterials on using mechanics to guide the design of acellular epicardial patches for the treatment of myocardial infarction.This technology aims to employ a biocompatible material patch to help reverse left ventricular remodeling and restore heart function after myocardial infarction by increasing the mechanical integrity of damaged heart tissues.However,its application is currently limited by widely scattered therapeutic efficacy.Here,we develop a biomechanics-based simulation platform that allows us to test,design and optimize the performance of an epicardial patch.We show that the widely scattered therapeutic efficacy of this technology can be attributed to a“pre-strain sensitivity”caused by attaching an elastic patch to a dynamically beating heart.To mitigate this challenge,we introduce a viscoelastic epicardial patch,designed at the so-called‘gel point’of the material,that effectively accommodates the cyclic deformation of the myocardium.This then leads to the fabrication and experimentally validated epicardial patch that outperforms all existing ones in restoring heart function after both acute and subacute myocardial infarction in rats.Our study also demonstrates the potential of employing viscoelastic interfaces for better integration of synthetic materials with biological tissues.
基金supported by the National Key Research and Development Program(2022YFC2402900)the Key Research and Development Program of Hainan Province(ZDYF2024SHFZ128)the Science and Technology Innovation Program of Hunan Province(2022RC1213),China.
文摘Objective:Drug-loaded mucoadhesive silk fibroin(SF)microneedle patch can overcome the limitations of low bioavailability and significant pain associated with traditional treatment methods,such as topical application or injection of triamcinolone for oral submucous fibrosis(OSF).However,these systems release the drug too quickly,failing to meet the clinical requirements.This study aims to construct a mucoadhesive SF microneedle patch pre-assembled with silk fibroin nanospheres(SFN)and explore its ability to sustain the release of triamcinolone in the treatment of OSF.Methods:SFN was pre-assembled via precipitation reaction and characterized by scanning electron microscope(SEM)for the morphology.The particle size andζ-potential were measured by dynamic light scattering(DLS).Triamcinolone was loaded onto SFN using a diffusional post-loading method.The effective loading of triamcinolone was confirmed using Fourier-transform infrared spectroscopy(FTIR).The concentration of unloaded triamcinolone was quantified by high-performance liquid chromatography.Drug encapsulation efficiency and loading capacity of SFN were then calculated to determine the optimal amount of drug loading.The SFN suspension was pre-mixed with SF solution to prepare the microneedle under-layer.The microneedle morphology was observed by SEM.Compression mechanical tests were performed to evaluate the fracture force of microneedles at different nanosphere contents(5%,10%,and 20%),determining the optimal pre-mixing ratio.Ex-vivo mouse oral mucosa permeation studies were performed to ascertain the insertion depth of the microneedles via histological sections.The adhesive top layer was synthesized using SF and tannic acid,with FTIR confirming its successful synthesis.Its viscoelasticity was characterized by a rheometer,and differential scanning calorimetry analyzed thermal properties.Tensile tests evaluated the interfacial bonding strength between the adhesive layer and microneedle base to ensure no detachment during use.Adhesion to wet oral mucosal tissues was tested and compared to commercial oral patches.Under the optimized conditions,the double-layered mucoadhesive microneedle patch with pre-assembled nanospheres was prepared.Its cell compatibility was evaluated by cell counting kit-8(CCK-8),live/dead staining,and phalloidin staining after co culturing with fibroblasts.The drug release experiment was conducted to demonstrate its sustained release efficacy.Results:SFN(mean diameter 46.25 nm)was successfully prepared.The maximum drug encapsulation efficiency was(63.88±1.09)%(corresponding loading capacity of SFN was(27.41±3.06)%when the weight ratio of triamcinolone/SFN was 0.5.The corporation of SFN did not affect microneedle morphology.The mechanical properties of microneedles decreased with increasing nanosphere amount.Only the fracture force of the group with 5%SFN[(0.07±0.01)N/needle]exceeded the minimum force required for mucosal penetration,thus selected as the optimal pre-mixing ratio.Histological sections confirmed that the SFN microneedles could penetrate the epithelial layer and deliver drugs to OSF affected areas.Adhesion strength between the microneedle base and top layer was(94.8±6.89)kPa,confirming strong bonding with no detachment during use.The wet adhesive strength of the double-layered mucoadhesive microneedle patch[(41.28±7.43)kPa]was significantly enhanced compared to commercial oral patches(4.5 kPa,P<0.01).CCK-8 and live/dead staining results confirmed no significant cytotoxicity.Drug release experiment showed the double-layered mucoadhesive microneedle patch with pre-assembled SFN enabled sustained release time of triamcinolone from 4 days to 14 days.Conclusion:Pre-assembling nanospheres in mucoadhesive SF microneedle patches can extend triamcinolone release time,meeting clinical requirements for sustained drug delivery.
基金Project(61105067)supported by the National Natural Science Foundation of China
文摘A new multi-species particle swarm optimization with a two-level hierarchical topology and the orthogonal learning strategy(OMSPSO) is proposed, which enhances the global search ability of particles and increases their convergence rates. The numerical results on 10 benchmark functions demonstrated the effectiveness of our proposed algorithm. Then, the proposed algorithm is presented to design a butterfly-shaped microstrip patch antenna. Combined with the HFSS solver, a butterfly-shaped patch antenna with a bandwidth of about 40.1% is designed by using the proposed OMSPSO. The return loss of the butterfly-shaped antenna is greater than 10 d B between 4.15 and 6.36 GHz. The antenna can serve simultaneously for the high-speed wireless computer networks(5.15–5.35 GHz) and the RFID systems(5.8 GHz).
