The most prospective method for certain structural failures and damages that cannot employ redundancy is self-repairing techniques, to ensure especially the maximum flight safety. Based on the characters of self-repai...The most prospective method for certain structural failures and damages that cannot employ redundancy is self-repairing techniques, to ensure especially the maximum flight safety. Based on the characters of self-repairing aircraft, this paper states some basic assumptions of the self-repairing aircraft, and puts forward some special new conceptions concerning the self-repairing aircraft: control input, operating input, command input, repair input and operating and control factor as well as their relationships. Thus it provides a simple and reliable mathematical model structure for the research on the self-repairing control of the aircraft.展开更多
A direct self-repairing control approach is proposed for helicopter via quantum control techniques and adaptive compensator when some complex faults occur. For a linear varying-parameter helicopter control system, the...A direct self-repairing control approach is proposed for helicopter via quantum control techniques and adaptive compensator when some complex faults occur. For a linear varying-parameter helicopter control system, the model reference adaptive control law is designed and an adaptive compensator is used for improving its self-re- pairing capability. To enhance anti-interference capability of helicopter, quantum control feedforward is added be- tween fault and disturbance. Simulation results illustrate the effectiveness and feasibility of the approach.展开更多
Tribological characteristics and self-repairing effect of hydroxy-magnesium silicate (HMS) dispersed in lubricant oil on steel-to-steel friction pairs with various surface roughness were analyzed.The friction-reductio...Tribological characteristics and self-repairing effect of hydroxy-magnesium silicate (HMS) dispersed in lubricant oil on steel-to-steel friction pairs with various surface roughness were analyzed.The friction-reduction,anti-wear and self-repairing performance of various surface roughness friction pairs were examined by friction testing machine.An operation comparison was made between SJ10W-40 lubricant with and without HMS.The surface morphology and elementary composition of the grinding cracks were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The results show that the lubrication state changes from boundary lubrication into mixed lubrication after operation in lubricant with HMS.The friction-reduction,anti-wear and self-repairing performance of the friction pairs with various surface roughness are distinctly different.There is a repairing film whose material is different from substrate material on the grinding cracks.In addition,Si,Mg,O,Al and other elements are deposited on the repairing film which contains nanocrystals of these elements.And HMS self-repairing material possesses superior performance of friction-reduction,anti-wear and self-repairing effects.展开更多
An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelast...An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelastic effect of shape memory alloy(SMA) and the cohering characteristic of repairing adhesive. These SMA wires and brittle fibers containing adhesives were embedded into concrete beams during concrete casting to form smart reinforced concrete beams. The self-repairing capacity of smart concrete beams was investigated by three-point bending tests. The experimental results show that SMA wires add self-restoration capacity,the concrete beams recover almost completely after incurring an extremely large deflection and the cracks are closed almost completely by the recovery forces of SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by the superelasticity. The adhesives released from the broken-open fibers fill voids and cracks. The repaired damage enables continued function and prevents further degradation.展开更多
Featuring low density and high specific strength, magnesium(Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properti...Featuring low density and high specific strength, magnesium(Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properties make them susceptible to corrosion in humid, seawater, soil,and chemical medium. Various strategies have revealed certain merits of protecting Mg alloys. Therein, engineering self-repairing coatings is considered as an effective strategy, because they can enable the timely repair for damaged areas, which brings about long-term protection for Mg alloys. In this review, self-repairing coatings on Mg alloys are summarized from two aspects, namely shape restoring coatings and function restoring coatings. Shape restoring coatings benefit for swelling, shrinking, or reassociating reversible chemical bonds to return to the original state and morphology when coatings broken;function self-repairing coatings depend on the release of inhibitors to generate new passive layers on the damaged areas. With the advancement of coating research and to fulfill the demanding requirements of applications, it is an inevitable trend to develop coatings that can integrate multiple functions(such as stimulus response, self-repairing, corrosion warning,and so on). As a novel carrier and barrier, porous solids, especially covalent organic frameworks(COFs), have been respected as the future development of self-repairing coatings on Mg alloys, due to their unique, diverse structures and adjustable functions.展开更多
As a kind of natural nanometer materials,the attapulgite has been widely used in industry,agriculture,environment,food substance,medicament and many other fields.Few researches about attapulgite used in lubricant oil ...As a kind of natural nanometer materials,the attapulgite has been widely used in industry,agriculture,environment,food substance,medicament and many other fields.Few researches about attapulgite used in lubricant oil as additive were made,and those were only at a preliminary stage of exploration.The tribological characteristics of attapulgite powders with the different contents added to CD 15W/40 lubricant oil were researched through"plane-on-plane"configuration friction and wear tester,and the self-repairing performance of 45#steel worn surface was examined via ring-on-block configuration test.XRD,SEM,EDS,TEM were employed to analyze the surface morphologies and elementary composition of the samples'worn surface.Furthermore,wear self-repairing mechanism of attapulgite additive to lubricant oil was explored.The results showed that:the optimal content of attapulgite powders in oil CD 15W/40 was 0.5 wt%,and the stable friction coefficient can be reduced to 0.02,then the friction reduction performance can be enhanced by 82.5%;Smooth worn surface were formed of the chemical reaction film containing elements O,Si,Fe;Friction reduction and self-repairing mechanism had a relation with the crystal structure of attapulgite.展开更多
A novel Mg-Al LDH film was in-situ prepared hydrothermally in an alkaline aqueous solution on an Al-alloyed AZ31 substrate.The structural,chemical and functional characteristics of the film were explored by means of s...A novel Mg-Al LDH film was in-situ prepared hydrothermally in an alkaline aqueous solution on an Al-alloyed AZ31 substrate.The structural,chemical and functional characteristics of the film were explored by means of scanning electron microscope(SEM),X-ray diffraction(XRD),energy dispersive spectrometer(EDS),polarization curve,AC impedance and salt immersion tests,respectively.The anti-corrosion results indicated that the Mg-Al LDH film on the Al-alloyed AZ31 surface could effectively protect the AZ31 from corrosion attack even after 90 days of immersion in 3.5 wt.%NaCl solution.The protection performance is surprisingly better than most of the reported coatings on Mg alloys.More interestingly,when the Mg-Al LDH film was scratched,the exposed Al-alloyed surface might gradually release metal ions and re-generate dense LDH nano-sheets in the corrosive environment to inhibit the further corrosion there,exhibiting a self-repairing behavior.The combination of the benign long-term protection and desirable self-repairing performance in this new process of surface-alloying and LDH-formation may significantly extend the practical application of magnesium alloys.展开更多
A new robust fault-tolerant controller scheme integrating a main controller and a compensator for the self-repairing flight control system is discussed.The main controller is designed for high performance of the origi...A new robust fault-tolerant controller scheme integrating a main controller and a compensator for the self-repairing flight control system is discussed.The main controller is designed for high performance of the original faultless system.The compensating controller can be seen as a standalone loop added to the system to compensate the effects of fault guaranteeing the stability of the system.A design method is proposed using nonlinear dynamic inverse control as the main controller and nonlinear extended state observer-based compensator.The stability of the whole closed-loop system is analyzed.Feasibility and validity of the new controller is demonstrated with an aircraft simulation example.展开更多
There are some critical issues hindering the practical applications of aqueous zinc-ion batteries(zIBs),although they possess high safety and low cost as one of promising energy storge devices,such as the Zn dendrite ...There are some critical issues hindering the practical applications of aqueous zinc-ion batteries(zIBs),although they possess high safety and low cost as one of promising energy storge devices,such as the Zn dendrite growth and the by-product of Zn_(4)SO_(4)(OH)_(6)-xH_(2)O(ZHS)resulted from some side reactions in a mild electrolyte.Herein,a compact and self-repairing solid electrolyte interface(SEl)film,as labeled the PVDF-Zn(TFSI)_(2)-ZHS coating[The PVDF and Zn(TFSI)_(2)are polyvinylidene fluoride and zinc bis(trifluoromethanesulfonyl)imide,respectively],which turns the in-situ generated ZHS into a beneficial ingredient onto the pre-coated PVDF-based composite coating layer containing Zn(TFSI)_(2),was designed and fabricated by a simple doctor blade method.It is shown that the SEl layer can effectively isolate Zn from the electrolyte and homogenize the Zn^(2+)flux,and thus effectively suppress side reactions and dendrites growth.Benefiting from the hybrid SEl layer,a symmetric cell exhibits a high cycling stability over 750h at 2.0 mA/cm^(2)and 2.0 mAh/cm^(2),and meanwhile,a full-cell,coupled with K^(+) pre-intercalationα-MnO_(2)(KMO)cathode,displays excellent rate performance,stable coulombic efficiency and an acceptable cycle life.This work provides a feasible approach for simple and scalable modification of Zn anodes to achieve high performance.展开更多
The friction reducing properties of sulfonated graphene as a lubricating additive were investigated using a four-ball machine tester with high carbon chromium bearing steels GCr15（SAE52100） friction pairs. The micro...The friction reducing properties of sulfonated graphene as a lubricating additive were investigated using a four-ball machine tester with high carbon chromium bearing steels GCr15（SAE52100） friction pairs. The microscopic morphology, elemental composition, and self-repairing properties were observed and analyzed by using scanning electronic microscopy（SEM）, X-ray diffraction（XRD） and digital microscopy. The relationships among sulfonated graphene ethanol solution concentration, friction coefficient, and abrasion loss were revealed. It was found that the optimal concentration of ethanol solution with the addition of sulfonated graphene was 0.15g/m L and the coefficient of friction was only 0.105 under certain condition. Then the stable chemical properties and good anti-corrosion properties of the metal-graphene layer were further confirmed using salt spray corrosion test. In summary, sulfonated graphene can be used as a new kind of self repairing additive, and it has excellent wear-resistant and self-repairing performances.展开更多
A hybrid remotely operated underwater vehicle( HROV) capable of working to the full ocean depth has been developed. In order for the vehicle to achieve a certain survivability level,a self-repairing control system( SR...A hybrid remotely operated underwater vehicle( HROV) capable of working to the full ocean depth has been developed. In order for the vehicle to achieve a certain survivability level,a self-repairing control system( SRCS) has been designed. It consists of two basic technologies,fault diagnosis and isolation( FDI) and reconfigurable control. For FDI,a model-based hierarchical fault diagnosis system is designed for the HROV. Then,control strategies which reconfigure the control system at intervals according to information from the FDI system are presented. Combining the two technologies,it can obtain the fundamental frame of SRCS for the HROV. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes,an assessment of the HROV's survivability is vitally needed before it enters operational service. This paper presents a new definition of survivability for underwater vehicles and develops a simple survivability model for the SRCS. As a result of survivability assessment for the SRCS,we are able to figure out the survivability of SRCS and make further optimization about it. The methodology developed herein is also applicable to other types of underwater vehicles.展开更多
Self-repairing coatings hold promise for prolonging the lifespan of steel structures and reducing carbon dioxide emissions from metal corrosion.Reversible chemistry-based intrinsic self-repairing has emerged as a cutt...Self-repairing coatings hold promise for prolonging the lifespan of steel structures and reducing carbon dioxide emissions from metal corrosion.Reversible chemistry-based intrinsic self-repairing has emerged as a cutting-edge strategy for addressing material damage.However,achieving effective repair at damaged coating interfaces remains challenging due to adhesion limitations between the coating and substrate.In this study,we propose an innovative approach to efficiently repair coating damage using photothermal-induced confined solid-liquid transition.We developed a unique structured coating by incorporating ther-moplastic epoxy resin(EP)into a polyethersulfone(PES)network skeleton through controlled reaction-induced phase separation.Additionally,we synthesized visible-light transmittable copper sulfide(CuS)nanocrystals as photothermal fillers to impart PES/EP-CuS coating with colorability.Upon near-infrared(NIR)laser irradiation,the EP phase undergoes confined solid-liquid transition at the crack site,enabling it to flow through the PES skeleton and seal the crack.This process promotes contact between damaged interfaces and closes the crack through interfacial tension.The PES/EP-CuS coating exhibited exceptional anti-corrosion restoration during service,showcasing its robust self-repairing capability.展开更多
A new self-repairing membrane for inflatable light weight structures such as rubber boats or Tensairity constructions is presented. Inspired by rapid self-sealing processes in plants, a thin soft cellular polyurethane...A new self-repairing membrane for inflatable light weight structures such as rubber boats or Tensairity constructions is presented. Inspired by rapid self-sealing processes in plants, a thin soft cellular polyurethane foam coating is applied on the inside of a fabric substrate, which closes the fissure if the membrane is punctured with a spike. Experimental tests are carried out with a purpose built setup by measuring the air mass flow through a leak in a damaged membrane sample. It is shown that the weight per unit area of the self-repairing foam as well as the curing of the two component PU-foam under an overpressure influence the repair efficiency. Curing the foam under overpressure affects the relative density as well as the microstructure of the foam coatings. Maximal median repair efficiencies of 0.999 have been obtained with 0.16 g.cm 2 foam cured at 1 bar overpressure. These results suggest that the bio-inspired technique has the potential to extend the functional integrity of injured inflatable structures dramatically.展开更多
Grain boundary cracks in flexible perovskite films can be repaired by filling with self-repairing polymers during the preparation and wearable operation.However,the self-repairing polymers are commonly active through ...Grain boundary cracks in flexible perovskite films can be repaired by filling with self-repairing polymers during the preparation and wearable operation.However,the self-repairing polymers are commonly active through external heating or humidification treatments,which cannot match with the human body's temperature tolerance of wearable devices.Herein,a body temperature-responsive shape memory polyurethane(SMPU)is demonstrated to achieve the real-time mechanical self-repairing of grain boundary cracks(~37°C).Furthermore,the strong intermolecular interaction between SMPU and the uncoordinated Pb2+and I−,can reduce the trap density in perovskite films.The blade-coated device achieves a power conversion efficiency(PCE)of 21.33%,which is among the best reported flexible perovskite solar cells(PSCs;0.10 cm2).Importantly,the device with SMPU can recover more than 80%of the PCE after 6000 cycles(bending radius:8 mm).Finally,the flexible PSCs are used for wearable solar power supply of a smartphone,which show great potential for self-repairing wearable electronics.展开更多
This paper describes the method of built-in self-repairing of RAM on board, designs hardware circuit, and logic for the RAM's faults self-repairing system based on FPGA. The key technology is that it utilizes FPGA...This paper describes the method of built-in self-repairing of RAM on board, designs hardware circuit, and logic for the RAM's faults self-repairing system based on FPGA. The key technology is that it utilizes FPGA to test RAM according to some algorithm to find out failure memory units and replace the faulty units with FPGA. Then it can build a memory that has no fault concern to external controller, and realizes the logic binding between external controller and RAM. Micro Controller Unit (MCU) can operate external RAM correctly even if RAM has some fault address units. Conventional MCS-51 is used to simulate the operation of MCU operating external memory. Simulation shows FPGA can complete the faulty address units' mapping and MCU can normally read and write external RAM. This design realizes the RAM's built-in self-repairing on board.展开更多
Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features...Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features of plants (variable stiffness due to pressure changes in cellular structures and rapid self-repair functions) that may be used as models for biomimetic projects.展开更多
In the face of harsh natural environment applications such as earth-orbiting and deep space satellites, underwater sea vehicles, strong electromagnetic interference and temperature stress,the circuits faults appear ea...In the face of harsh natural environment applications such as earth-orbiting and deep space satellites, underwater sea vehicles, strong electromagnetic interference and temperature stress,the circuits faults appear easily. Circuit faults will inevitably lead to serious losses of availability or impeded mission success without self-repair over the mission duration. Traditional fault-repair methods based on redundant fault-tolerant technique are straightforward to implement, yet their area, power and weight cost can be excessive. Moreover they utilize all plug-in or component level circuits to realize redundant backup, such that their applicability is limited. Hence, a novel selfrepair technology based on evolvable hardware（EHW） and reparation balance technology（RBT） is proposed. Its cost is low, and fault self-repair of various circuits and devices can be realized through dynamic configuration. Making full use of the fault signals, correcting circuit can be found through EHW technique to realize the balance and compensation of the fault output-signals. In this paper, the self-repair model was analyzed which based on EHW and RBT technique, the specific self-repair strategy was studied, the corresponding self-repair circuit fault system was designed, and the typical faults were simulated and analyzed which combined with the actual electronic devices. Simulation results demonstrated that the proposed fault self-repair strategy was feasible. Compared to traditional techniques, fault self-repair based on EHW consumes fewer hardware resources, and the scope of fault self-repair was expanded significantly.展开更多
Since digital circuits have been widely and thoroughly applied in various fields, electronic systems are increasingly more complicated and require greater reliability. Faults may occur in electronic systems in complic...Since digital circuits have been widely and thoroughly applied in various fields, electronic systems are increasingly more complicated and require greater reliability. Faults may occur in electronic systems in complicated environments. If immediate field repairs are not made on the faults, electronic systems will not run normally, and this will lead to serious losses. The traditional method for improving system reliability based on redundant fault-tolerant technique has been unable to meet the requirements. Therefore, on the basis of(evolvable hardware)-based and(reparation balance technology)-based electronic circuit fault self-repair strategy proposed in our preliminary work, the optimal design of rectification circuits(RTCs) in electronic circuit fault self-repair based on global signal optimization is deeply researched in this paper. First of all, the basic theory of RTC optimal design based on global signal optimization is proposed. Secondly, relevant considerations and suitable ranges are analyzed. Then, the basic flow of RTC optimal design is researched. Eventually, a typical circuit is selected for simulation verification, and detailed simulated analysis is made on five circumstances that occur during RTC evolution. The simulation results prove that compared with the conventional design method based RTC, the global signal optimization design method based RTC is lower in hardware cost, faster in circuit evolution, higher in convergent precision, and higher in circuit evolution success rate. Therefore, the global signal optimization based RTC optimal design method applied in the electronic circuit fault self-repair technology is proven to be feasible, effective, and advantageous.展开更多
The existing self-repair methods,evolvable hardware and embryonic electronics( embryonics) are analyzed. Based on the advantages and disadvantages of the existing self-repair methods,a novel self-repair method named e...The existing self-repair methods,evolvable hardware and embryonic electronics( embryonics) are analyzed. Based on the advantages and disadvantages of the existing self-repair methods,a novel self-repair method named elimination-evolution self-repair method is proposed. The system can be repaired through elimination in real time and evolved to optimize the allocation of system resources with this method. The proposed self-repair method not only ensures the speed of the system's self-repair,but also makes full use of system resources to improve the system's self-repair capacity and provides a new self-repair approach for bio-inspired electronic system. In the end,the advantages of the proposed eliminationevolution self-repair method are verified through a simulation experiment.展开更多
The discipline of damage tolerance assessment has experienced significant advancements due to the emergence of smart materials and self-repairable structures.This review offers a comprehensive look into both tradition...The discipline of damage tolerance assessment has experienced significant advancements due to the emergence of smart materials and self-repairable structures.This review offers a comprehensive look into both traditional and innovative methodologies employed in damage tolerance assessment.After a detailed exploration of damage tolerance concepts and their historical progression,the review juxtaposes the proven techniques of damage assessment with the cutting-edge innovations brought about by smart materials and self-repairable structures.The subsequent sections delve into the synergistic integration of smart materials with self-repairable structures,marking a pivotal stride in damage tolerance by establishing an autonomous system for immediate damage identification and self-repair.This holistic approach broadens the applicability of these technologies across diverse sectors yet brings forth unique challenges demanding further innovation and research.Additionally,the review examines future prospects that combine advanced manufacturing processes with data-centric methodologies,amplifying the capabilities of these‘intelligent’structures.The review culminates by highlighting the transformative potential of this union between smart materials and self-repairable structures,promoting a sustainable and efficient engineering paradigm.展开更多
文摘The most prospective method for certain structural failures and damages that cannot employ redundancy is self-repairing techniques, to ensure especially the maximum flight safety. Based on the characters of self-repairing aircraft, this paper states some basic assumptions of the self-repairing aircraft, and puts forward some special new conceptions concerning the self-repairing aircraft: control input, operating input, command input, repair input and operating and control factor as well as their relationships. Thus it provides a simple and reliable mathematical model structure for the research on the self-repairing control of the aircraft.
基金Supported by the National Natural Science Foundation of China(61074080)the Innovation Foundation for Aeronautical Science and Technology(08C52001)~~
文摘A direct self-repairing control approach is proposed for helicopter via quantum control techniques and adaptive compensator when some complex faults occur. For a linear varying-parameter helicopter control system, the model reference adaptive control law is designed and an adaptive compensator is used for improving its self-re- pairing capability. To enhance anti-interference capability of helicopter, quantum control feedforward is added be- tween fault and disturbance. Simulation results illustrate the effectiveness and feasibility of the approach.
基金Projects(50735006,50904072) supported by the National Natural Science Foundation of ChinaProject(2007CB607601) supported by the National Basic Research Program of China
文摘Tribological characteristics and self-repairing effect of hydroxy-magnesium silicate (HMS) dispersed in lubricant oil on steel-to-steel friction pairs with various surface roughness were analyzed.The friction-reduction,anti-wear and self-repairing performance of various surface roughness friction pairs were examined by friction testing machine.An operation comparison was made between SJ10W-40 lubricant with and without HMS.The surface morphology and elementary composition of the grinding cracks were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The results show that the lubrication state changes from boundary lubrication into mixed lubrication after operation in lubricant with HMS.The friction-reduction,anti-wear and self-repairing performance of the friction pairs with various surface roughness are distinctly different.There is a repairing film whose material is different from substrate material on the grinding cracks.In addition,Si,Mg,O,Al and other elements are deposited on the repairing film which contains nanocrystals of these elements.And HMS self-repairing material possesses superior performance of friction-reduction,anti-wear and self-repairing effects.
基金Project(50538020) supported by the National Natural Science Foundation of ChinaProject(20070421050) supported by China Postdoctoral Science Foundation
文摘An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelastic effect of shape memory alloy(SMA) and the cohering characteristic of repairing adhesive. These SMA wires and brittle fibers containing adhesives were embedded into concrete beams during concrete casting to form smart reinforced concrete beams. The self-repairing capacity of smart concrete beams was investigated by three-point bending tests. The experimental results show that SMA wires add self-restoration capacity,the concrete beams recover almost completely after incurring an extremely large deflection and the cracks are closed almost completely by the recovery forces of SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by the superelasticity. The adhesives released from the broken-open fibers fill voids and cracks. The repaired damage enables continued function and prevents further degradation.
基金the financial support from the National Natural Science Foundation of China (Nos.52204389,U19A2084 and 52234009)the National Key Research and Development Program (No.2022YFE0122000)Program for the Central University Youth Innovation Team。
文摘Featuring low density and high specific strength, magnesium(Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properties make them susceptible to corrosion in humid, seawater, soil,and chemical medium. Various strategies have revealed certain merits of protecting Mg alloys. Therein, engineering self-repairing coatings is considered as an effective strategy, because they can enable the timely repair for damaged areas, which brings about long-term protection for Mg alloys. In this review, self-repairing coatings on Mg alloys are summarized from two aspects, namely shape restoring coatings and function restoring coatings. Shape restoring coatings benefit for swelling, shrinking, or reassociating reversible chemical bonds to return to the original state and morphology when coatings broken;function self-repairing coatings depend on the release of inhibitors to generate new passive layers on the damaged areas. With the advancement of coating research and to fulfill the demanding requirements of applications, it is an inevitable trend to develop coatings that can integrate multiple functions(such as stimulus response, self-repairing, corrosion warning,and so on). As a novel carrier and barrier, porous solids, especially covalent organic frameworks(COFs), have been respected as the future development of self-repairing coatings on Mg alloys, due to their unique, diverse structures and adjustable functions.
基金National Natural Science Foundations of China(50735006,50904072)"973"Project(2007CB607601)China Postdoctoral Science Foundation(20090461452)
文摘As a kind of natural nanometer materials,the attapulgite has been widely used in industry,agriculture,environment,food substance,medicament and many other fields.Few researches about attapulgite used in lubricant oil as additive were made,and those were only at a preliminary stage of exploration.The tribological characteristics of attapulgite powders with the different contents added to CD 15W/40 lubricant oil were researched through"plane-on-plane"configuration friction and wear tester,and the self-repairing performance of 45#steel worn surface was examined via ring-on-block configuration test.XRD,SEM,EDS,TEM were employed to analyze the surface morphologies and elementary composition of the samples'worn surface.Furthermore,wear self-repairing mechanism of attapulgite additive to lubricant oil was explored.The results showed that:the optimal content of attapulgite powders in oil CD 15W/40 was 0.5 wt%,and the stable friction coefficient can be reduced to 0.02,then the friction reduction performance can be enhanced by 82.5%;Smooth worn surface were formed of the chemical reaction film containing elements O,Si,Fe;Friction reduction and self-repairing mechanism had a relation with the crystal structure of attapulgite.
基金supported by the National Science Foundation of China(key project grant No.51731008 and general project grant No.51671163).
文摘A novel Mg-Al LDH film was in-situ prepared hydrothermally in an alkaline aqueous solution on an Al-alloyed AZ31 substrate.The structural,chemical and functional characteristics of the film were explored by means of scanning electron microscope(SEM),X-ray diffraction(XRD),energy dispersive spectrometer(EDS),polarization curve,AC impedance and salt immersion tests,respectively.The anti-corrosion results indicated that the Mg-Al LDH film on the Al-alloyed AZ31 surface could effectively protect the AZ31 from corrosion attack even after 90 days of immersion in 3.5 wt.%NaCl solution.The protection performance is surprisingly better than most of the reported coatings on Mg alloys.More interestingly,when the Mg-Al LDH film was scratched,the exposed Al-alloyed surface might gradually release metal ions and re-generate dense LDH nano-sheets in the corrosive environment to inhibit the further corrosion there,exhibiting a self-repairing behavior.The combination of the benign long-term protection and desirable self-repairing performance in this new process of surface-alloying and LDH-formation may significantly extend the practical application of magnesium alloys.
基金supported by the National Natural Science Foundation of China (60874117)the 111 Project (B07009)
文摘A new robust fault-tolerant controller scheme integrating a main controller and a compensator for the self-repairing flight control system is discussed.The main controller is designed for high performance of the original faultless system.The compensating controller can be seen as a standalone loop added to the system to compensate the effects of fault guaranteeing the stability of the system.A design method is proposed using nonlinear dynamic inverse control as the main controller and nonlinear extended state observer-based compensator.The stability of the whole closed-loop system is analyzed.Feasibility and validity of the new controller is demonstrated with an aircraft simulation example.
基金supported by the National Natural Science Foundation of Guangdong Province(No.2022A1515010173)the National Natural Science Foundation of China(No.22178125)and the 111 Project(No.B20003).
文摘There are some critical issues hindering the practical applications of aqueous zinc-ion batteries(zIBs),although they possess high safety and low cost as one of promising energy storge devices,such as the Zn dendrite growth and the by-product of Zn_(4)SO_(4)(OH)_(6)-xH_(2)O(ZHS)resulted from some side reactions in a mild electrolyte.Herein,a compact and self-repairing solid electrolyte interface(SEl)film,as labeled the PVDF-Zn(TFSI)_(2)-ZHS coating[The PVDF and Zn(TFSI)_(2)are polyvinylidene fluoride and zinc bis(trifluoromethanesulfonyl)imide,respectively],which turns the in-situ generated ZHS into a beneficial ingredient onto the pre-coated PVDF-based composite coating layer containing Zn(TFSI)_(2),was designed and fabricated by a simple doctor blade method.It is shown that the SEl layer can effectively isolate Zn from the electrolyte and homogenize the Zn^(2+)flux,and thus effectively suppress side reactions and dendrites growth.Benefiting from the hybrid SEl layer,a symmetric cell exhibits a high cycling stability over 750h at 2.0 mA/cm^(2)and 2.0 mAh/cm^(2),and meanwhile,a full-cell,coupled with K^(+) pre-intercalationα-MnO_(2)(KMO)cathode,displays excellent rate performance,stable coulombic efficiency and an acceptable cycle life.This work provides a feasible approach for simple and scalable modification of Zn anodes to achieve high performance.
基金Funded by the National Natural Science Foundation of China(Nos.51675230&51405195)
文摘The friction reducing properties of sulfonated graphene as a lubricating additive were investigated using a four-ball machine tester with high carbon chromium bearing steels GCr15（SAE52100） friction pairs. The microscopic morphology, elemental composition, and self-repairing properties were observed and analyzed by using scanning electronic microscopy（SEM）, X-ray diffraction（XRD） and digital microscopy. The relationships among sulfonated graphene ethanol solution concentration, friction coefficient, and abrasion loss were revealed. It was found that the optimal concentration of ethanol solution with the addition of sulfonated graphene was 0.15g/m L and the coefficient of friction was only 0.105 under certain condition. Then the stable chemical properties and good anti-corrosion properties of the metal-graphene layer were further confirmed using salt spray corrosion test. In summary, sulfonated graphene can be used as a new kind of self repairing additive, and it has excellent wear-resistant and self-repairing performances.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51109132)Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110073120015)
文摘A hybrid remotely operated underwater vehicle( HROV) capable of working to the full ocean depth has been developed. In order for the vehicle to achieve a certain survivability level,a self-repairing control system( SRCS) has been designed. It consists of two basic technologies,fault diagnosis and isolation( FDI) and reconfigurable control. For FDI,a model-based hierarchical fault diagnosis system is designed for the HROV. Then,control strategies which reconfigure the control system at intervals according to information from the FDI system are presented. Combining the two technologies,it can obtain the fundamental frame of SRCS for the HROV. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes,an assessment of the HROV's survivability is vitally needed before it enters operational service. This paper presents a new definition of survivability for underwater vehicles and develops a simple survivability model for the SRCS. As a result of survivability assessment for the SRCS,we are able to figure out the survivability of SRCS and make further optimization about it. The methodology developed herein is also applicable to other types of underwater vehicles.
基金the financial support through the National Natural Science Foundation of China(No.52271355)the Henan Provincial Science and Technology Research Joint Fund-Young Scientist Project(No.225200810108)+3 种基金the Basic Scientific Research Fund Project of Henan Academy of Sciences(No.230618023)the Research Startup Fund of Henan Academy of Sciences(Nos.231818027,232018001)the High-level Achievement Award and Cultivation Project of Henan Academy of Sciences(No.242218021)the Zhuhai City Industry-University-Research Cooperation Project(No.ZH22017001210148PWC).
文摘Self-repairing coatings hold promise for prolonging the lifespan of steel structures and reducing carbon dioxide emissions from metal corrosion.Reversible chemistry-based intrinsic self-repairing has emerged as a cutting-edge strategy for addressing material damage.However,achieving effective repair at damaged coating interfaces remains challenging due to adhesion limitations between the coating and substrate.In this study,we propose an innovative approach to efficiently repair coating damage using photothermal-induced confined solid-liquid transition.We developed a unique structured coating by incorporating ther-moplastic epoxy resin(EP)into a polyethersulfone(PES)network skeleton through controlled reaction-induced phase separation.Additionally,we synthesized visible-light transmittable copper sulfide(CuS)nanocrystals as photothermal fillers to impart PES/EP-CuS coating with colorability.Upon near-infrared(NIR)laser irradiation,the EP phase undergoes confined solid-liquid transition at the crack site,enabling it to flow through the PES skeleton and seal the crack.This process promotes contact between damaged interfaces and closes the crack through interfacial tension.The PES/EP-CuS coating exhibited exceptional anti-corrosion restoration during service,showcasing its robust self-repairing capability.
文摘A new self-repairing membrane for inflatable light weight structures such as rubber boats or Tensairity constructions is presented. Inspired by rapid self-sealing processes in plants, a thin soft cellular polyurethane foam coating is applied on the inside of a fabric substrate, which closes the fissure if the membrane is punctured with a spike. Experimental tests are carried out with a purpose built setup by measuring the air mass flow through a leak in a damaged membrane sample. It is shown that the weight per unit area of the self-repairing foam as well as the curing of the two component PU-foam under an overpressure influence the repair efficiency. Curing the foam under overpressure affects the relative density as well as the microstructure of the foam coatings. Maximal median repair efficiencies of 0.999 have been obtained with 0.16 g.cm 2 foam cured at 1 bar overpressure. These results suggest that the bio-inspired technique has the potential to extend the functional integrity of injured inflatable structures dramatically.
基金National Key R&D Program of China,Grant/Award Number:2018YFA0208501National Natural Science Foundation of China,Grant/Award Numbers:21401167,22005131,22075296,51803217,5210031012,52173169,91963212+5 种基金Beijing Nova Program from Beijing Municipal ScienceTechnology Commission,Grant/Award Number:Z201100006820037Beijing National Laboratory for Molecular Sciences,Grant/Award Number:BNLMSCXXM-202005Youth Innovation Promotion Association CAS,Grant/Award Number:2020032Key R&D and Promotion Project of Henan Province,Grant/Award Number:192102210032Outstanding Young Talent Research Fund of Zhengzhou University。
文摘Grain boundary cracks in flexible perovskite films can be repaired by filling with self-repairing polymers during the preparation and wearable operation.However,the self-repairing polymers are commonly active through external heating or humidification treatments,which cannot match with the human body's temperature tolerance of wearable devices.Herein,a body temperature-responsive shape memory polyurethane(SMPU)is demonstrated to achieve the real-time mechanical self-repairing of grain boundary cracks(~37°C).Furthermore,the strong intermolecular interaction between SMPU and the uncoordinated Pb2+and I−,can reduce the trap density in perovskite films.The blade-coated device achieves a power conversion efficiency(PCE)of 21.33%,which is among the best reported flexible perovskite solar cells(PSCs;0.10 cm2).Importantly,the device with SMPU can recover more than 80%of the PCE after 6000 cycles(bending radius:8 mm).Finally,the flexible PSCs are used for wearable solar power supply of a smartphone,which show great potential for self-repairing wearable electronics.
文摘This paper describes the method of built-in self-repairing of RAM on board, designs hardware circuit, and logic for the RAM's faults self-repairing system based on FPGA. The key technology is that it utilizes FPGA to test RAM according to some algorithm to find out failure memory units and replace the faulty units with FPGA. Then it can build a memory that has no fault concern to external controller, and realizes the logic binding between external controller and RAM. Micro Controller Unit (MCU) can operate external RAM correctly even if RAM has some fault address units. Conventional MCS-51 is used to simulate the operation of MCU operating external memory. Simulation shows FPGA can complete the faulty address units' mapping and MCU can normally read and write external RAM. This design realizes the RAM's built-in self-repairing on board.
文摘Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features of plants (variable stiffness due to pressure changes in cellular structures and rapid self-repair functions) that may be used as models for biomimetic projects.
基金supported by the National Natural Science Foundation of China (Nos. 61271153, 61372039)
文摘In the face of harsh natural environment applications such as earth-orbiting and deep space satellites, underwater sea vehicles, strong electromagnetic interference and temperature stress,the circuits faults appear easily. Circuit faults will inevitably lead to serious losses of availability or impeded mission success without self-repair over the mission duration. Traditional fault-repair methods based on redundant fault-tolerant technique are straightforward to implement, yet their area, power and weight cost can be excessive. Moreover they utilize all plug-in or component level circuits to realize redundant backup, such that their applicability is limited. Hence, a novel selfrepair technology based on evolvable hardware（EHW） and reparation balance technology（RBT） is proposed. Its cost is low, and fault self-repair of various circuits and devices can be realized through dynamic configuration. Making full use of the fault signals, correcting circuit can be found through EHW technique to realize the balance and compensation of the fault output-signals. In this paper, the self-repair model was analyzed which based on EHW and RBT technique, the specific self-repair strategy was studied, the corresponding self-repair circuit fault system was designed, and the typical faults were simulated and analyzed which combined with the actual electronic devices. Simulation results demonstrated that the proposed fault self-repair strategy was feasible. Compared to traditional techniques, fault self-repair based on EHW consumes fewer hardware resources, and the scope of fault self-repair was expanded significantly.
基金supported by the National Natural Science Foundation of China (Nos. 61271153, 61372039)
文摘Since digital circuits have been widely and thoroughly applied in various fields, electronic systems are increasingly more complicated and require greater reliability. Faults may occur in electronic systems in complicated environments. If immediate field repairs are not made on the faults, electronic systems will not run normally, and this will lead to serious losses. The traditional method for improving system reliability based on redundant fault-tolerant technique has been unable to meet the requirements. Therefore, on the basis of(evolvable hardware)-based and(reparation balance technology)-based electronic circuit fault self-repair strategy proposed in our preliminary work, the optimal design of rectification circuits(RTCs) in electronic circuit fault self-repair based on global signal optimization is deeply researched in this paper. First of all, the basic theory of RTC optimal design based on global signal optimization is proposed. Secondly, relevant considerations and suitable ranges are analyzed. Then, the basic flow of RTC optimal design is researched. Eventually, a typical circuit is selected for simulation verification, and detailed simulated analysis is made on five circumstances that occur during RTC evolution. The simulation results prove that compared with the conventional design method based RTC, the global signal optimization design method based RTC is lower in hardware cost, faster in circuit evolution, higher in convergent precision, and higher in circuit evolution success rate. Therefore, the global signal optimization based RTC optimal design method applied in the electronic circuit fault self-repair technology is proven to be feasible, effective, and advantageous.
基金National Natural Science Foundations of China(Nos.61372039,61271153)
文摘The existing self-repair methods,evolvable hardware and embryonic electronics( embryonics) are analyzed. Based on the advantages and disadvantages of the existing self-repair methods,a novel self-repair method named elimination-evolution self-repair method is proposed. The system can be repaired through elimination in real time and evolved to optimize the allocation of system resources with this method. The proposed self-repair method not only ensures the speed of the system's self-repair,but also makes full use of system resources to improve the system's self-repair capacity and provides a new self-repair approach for bio-inspired electronic system. In the end,the advantages of the proposed eliminationevolution self-repair method are verified through a simulation experiment.
文摘The discipline of damage tolerance assessment has experienced significant advancements due to the emergence of smart materials and self-repairable structures.This review offers a comprehensive look into both traditional and innovative methodologies employed in damage tolerance assessment.After a detailed exploration of damage tolerance concepts and their historical progression,the review juxtaposes the proven techniques of damage assessment with the cutting-edge innovations brought about by smart materials and self-repairable structures.The subsequent sections delve into the synergistic integration of smart materials with self-repairable structures,marking a pivotal stride in damage tolerance by establishing an autonomous system for immediate damage identification and self-repair.This holistic approach broadens the applicability of these technologies across diverse sectors yet brings forth unique challenges demanding further innovation and research.Additionally,the review examines future prospects that combine advanced manufacturing processes with data-centric methodologies,amplifying the capabilities of these‘intelligent’structures.The review culminates by highlighting the transformative potential of this union between smart materials and self-repairable structures,promoting a sustainable and efficient engineering paradigm.
