Designing and preparing a compatible electromagnetic interference(EMI)shielding,radar and infrared stealth material exhibits significant prospect in the military field.Hence,a novel conductive/magnetic polyimide-based...Designing and preparing a compatible electromagnetic interference(EMI)shielding,radar and infrared stealth material exhibits significant prospect in the military field.Hence,a novel conductive/magnetic polyimide-based nonwoven fabric(PFN_y)is prepared by alkali treatment,Fe~(3+)ion exchange,thermal reduction,and electroless nickel(Ni)plating process.Its impedance/insulation characteristics can be easily adjusted by controlling the in situ growth of Fe_(3)O_(4) and electroless nickel plating.Subsequently,a new strategy of constructing hierarchical dual-gradient impedance/insulation structure is implemented to achieve EMI shielding,radar and infrared stealth via stacking PFN_y with gradually decreased impedance/insulation characteristics from top to bottom.The formation of impedance matching gradient structure promotes effective introduction and dissipation of electromagnetic waves,endowing the composite with outstanding EMI shielding and radar stealth performance.Meanwhile,the construction of thermal insulation gradient structure can effectively inhibit thermal radiation from target,bringing an excellent infrared stealth performance.Importantly,the strong interfacial interactions between Fe_(3)O_(4),Ni and polyimide fiber accelerate PFNy to resist the stresses originated from high-temperature heat source,achieving a compatible high-temperature resistant radar/infrared stealth performance.Such excellent comprehensive properties endow it with a great potential in high-temperature military camouflage applications against enemy radar and infrared detection.展开更多
Designing and manufacturing compatible multi-band stealth materials remains a great challenge. In this work, a silver-metalized polyimide photochromic composite foam is successfully fabricated by self-activating elect...Designing and manufacturing compatible multi-band stealth materials remains a great challenge. In this work, a silver-metalized polyimide photochromic composite foam is successfully fabricated by self-activating electroless silver-plating on the surface of the polyimide skeleton and followed by applying a photochromic coating on the upper surface. The effective loading of silver nanoparticles facilitates the rational construction of a conductive network in foam, improving the efficient dissipation of incident electromagnetic waves. In addition, the interconnected conductive network successfully endows it with an excellent Joule heating capability, which can be employed to effectively remove ice and/or mitigate the impact of water vapor on radar stealth performance in cold and wet weather. Besides, the low emissivity silver plating combined with superior thermal insulation of foam enables the material with excellent infrared stealth performance. Moreover, the modulation of self-adaptive photochromic coating brings a prominent visual stealth performance under different sunlight backgrounds. As a result, such excellent radar and infrared stealth performance combined with the adaptive color-switching capability provides the foam with great potential for preparing compatible multi-band materials.展开更多
Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening ...Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.展开更多
Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR clo...Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR cloaking mechanisms and functional integration limitations.Here,we propose a multiscale hierarchical structure design,integrating wrinkled MXene IR shielding layer and flexible Fe_(3)O_(4)@C/PDMS microwave absorption layer.The top wrinkled MXene layer induces the intensive diffuse reflection effect,shielding IR radiation signals while allowing microwave to pass through.Meanwhile,the permeable microwaves are assimilated into the bottom Fe_(3)O_(4)@C/PDMS layer via strong magneto-electric synergy.Through theoretical and experimental optimization,the assembled stealth devices realize a near-perfect stealth capability in both X-band(8–12 GHz)and long-wave infrared(8–14μm)wavelength ranges.Specifically,it delivers a radar cross-section reduction of−20 dB m^(2),a large apparent temperature modulation range(ΔT=70℃),and a low average IR emissivity of 0.35.Additionally,the optimal device demonstrates exceptional curved surface conformability,self-cleaning capability(contact angle≈129°),and abrasion resistance(recovery time≈5 s).This design strategy promotes the development of multispectral stealth technology and reinforces its applicability and durability in complex and hostile environments.展开更多
Multifunctional compatible stealth materials have emerged as the focal point of contemporary protection technology research and vanadium-based nanomaterials play a pivotal role in the development of advanced stealth m...Multifunctional compatible stealth materials have emerged as the focal point of contemporary protection technology research and vanadium-based nanomaterials play a pivotal role in the development of advanced stealth materials.Here,a compatible stealth aerogel is successfully synthesized by employing mixed-valence decavanadate as the vanadium oxide(VO_(x))molecular model.Ultralight{V^(Ⅳ)VV_(9)}/MXene aerogel(0.0429 g cm^(-3))exhibits exceptional radar stealth performance with a minimal reflection loss(RL_(min))of−57.74 dB(99.9998%EMW absorption)and a significantly superior radar cross section reduction value of 26.77 dB m2.The aerogel’s exceptional properties,including a low infrared(IR)emissivity(0.479)and a low thermal conductivity of(32.30 mW m^(-1)K^(-1)),are crucial for enabling compatibility with IR and thermal stealth technologies.The presence of a mixed-valence polyoxovanadate cluster leads to an increase in the Schottky barrier and enhances magnetic properties,consequently boosting interfacial polarization and contributing to magnetic losses during electromagnetic wave(EMW)absorption.Consequently,altering the number of valence electrons significantly enhances the compatible stealth capabilities.These findings contribute significantly to our comprehension of how microstructure impacts EMW absorption processes and provide a basis for further research into the development of VO_(x)-based compatible stealth materials.展开更多
As modern communication and detection technologies advance at a swift pace,multifunctional electromagnetic interference(EMI)shielding materials with active/positive infrared stealth,hydrophobicity,and electric-thermal...As modern communication and detection technologies advance at a swift pace,multifunctional electromagnetic interference(EMI)shielding materials with active/positive infrared stealth,hydrophobicity,and electric-thermal conversion ability have received extensive attention.Meeting the aforesaid requirements simultaneously remains a huge challenge.In this research,the melamine foam(MF)/polypyrrole(PPy)nanowire arrays(MF@PPy)were fabricated via one-step electrochemical polymerization.The hierarchical MF@PPy foam was composed of three-dimensional PPy micro-skeleton and ordered PPy nanowire arrays.Due to the upwardly grown PPy nanowire arrays,the MF@PPy foam possessed good hydrophobicity ability with a water contact angle of 142.00°and outstanding stability under various harsh environments.Meanwhile,the MF@PPy foam showed excellent thermal insulation property on account of the low thermal conductivity and elongated ligament characteristic of PPy nanowire arrays.Furthermore,taking advantage of the high conductivity(128.2 S m^(-1)),the MF@PPy foam exhibited rapid Joule heating under 3 V,resulting in dynamic infrared stealth and thermal camouflage effects.More importantly,the MF@PPy foam exhibited remarkable EMI shielding effectiveness values of 55.77 dB and 19,928.57 dB cm^(2)g^(-1).Strong EMI shielding was put down to the hierarchically porous PPy structure,which offered outstanding impedance matching,conduction loss,and multiple attenuations.This innovative approach provides significant insights to the development of advanced multifunctional EMI shielding foams by constructing PPy nanowire arrays,showing great applications in both military and civilian fields.展开更多
Gallium oxide(Ga_(2)O_(3))is an ultra-wide bandgap semiconductor with excellent potential for high-power and ultraviolet optoelectronic device applications.High-performance Ga_(2)O_(3)-based high-power devices rely he...Gallium oxide(Ga_(2)O_(3))is an ultra-wide bandgap semiconductor with excellent potential for high-power and ultraviolet optoelectronic device applications.High-performance Ga_(2)O_(3)-based high-power devices rely heavily on precise processing,especially in wafer dicing.Laser stealth dicing(LSD)is an innova-tive laser technology that utilizes a focused laser to create subsurface modifications in the wafer without surface damage.LSD has broad application prospects in the field of semiconductor precision processing.In this work,the idea of achieving high-quality dicing ofβ-Ga_(2)O_(3) wafers via LSD was proposed.A com-bination of atomistic simulations and experiments was used to understand the underlying mechanism of LSD ofβ-Ga_(2)O_(3) wafers.On the one hand,the laser loading and fracture process ofβ-Ga_(2)O_(3) wafers were simulated using molecular dynamics(MD)methods as well as a machine learning potential.The effects of single-pulse energy on LSD were analyzed through the lattice residual pressure,the final total energy of the system,the internal atomic strain,and the maximum stress value during uniaxial tension.On the other hand,based on the MD simulations,LSD was successfully performed onβ-Ga_(2)O_(3) wafers along three main crystal planes in the laboratory,resulting in good surface quality.This work not only provides profound optimization strategies for the LSD process ofβ-Ga_(2)O_(3),establishing the foundation for high-quality dicing ofβ-Ga_(2)O_(3) wafers,but also verifies the accuracy of MD simulations in predict-ing trends related to the LSD,offering a potential approach for high-quality dicing of other materials in future research.展开更多
Metasurfaces,which are two-dimensional arrays of subwavelength elements,enable versatile control of electromagnetic waves,thereby paving the way for advancements in electromagnetic stealth.Electromagnetic stealth aims...Metasurfaces,which are two-dimensional arrays of subwavelength elements,enable versatile control of electromagnetic waves,thereby paving the way for advancements in electromagnetic stealth.Electromagnetic stealth aims to diminish object visibility to radar or other sensors by minimizing their reflection,scattering,or emission of electromagnetic waves.This paper reviews the latest works in microwave electromagnetic stealth devices utilizing metasurfaces,including absorbing,scattering,cloaking and multifunctional stealth techniques.A comprehensive analysis and characterization of these stealth metasurface based devices are presented,focusing on their working principles,performance characteristics,and the associated challenges.Additionally,we explore prospects and opportunities for further research.This paper offers a thorough and upto-date survey of the current status and future directions of this emerging field.展开更多
The investigation of absorption-led shielding mechanisms has now made practical progress as a result of the concept of green EM shielding.The extant studies primarily concentrate on the introduction of mag-netic parti...The investigation of absorption-led shielding mechanisms has now made practical progress as a result of the concept of green EM shielding.The extant studies primarily concentrate on the introduction of mag-netic particles into the system,with the objective of enhancing the absorption rate(A)through dielectric-magnetic modulation for absorption-led electromagnetic shielding.In contrast,this paper presents a novel approach whereby PVA,glycerol,and MXene are combined into an organohydrogel(PMG)with oriented pores.This results in the creation of a non-magnetic medium that exhibits high absorption loss in mul-tiple bands,thereby establishing a novel shielding system.The PMG20-3 organohydrogel(0.78 wt%MX-ene)has a shielding performance in the X-band of 42.34 dB(A/R=1).In the terahertz band,the organic hydrogel gel exhibits an absorption rate of 99.9%,a performance that exceeds that of the majority of previously reported systems.The PMG gel displays remarkable flexibility and strength,with a hysteresis return line that remains stable under 1000 compression cycles.Additionally,it offers versatile sensing capabilities and infrared stealth.The findings of this study offer novel insights that may facilitate the accelerated utilization of innovative multifunctional and environmentally conscious electromagnetic in-terference(EMI)shielding materials.展开更多
Designing and fabricating a compatible low-reflectivity electromagnetic interference(EMI)shielding/high-temperature resistant infrared stealth material possesses a critical significance in the field of military.Hence,...Designing and fabricating a compatible low-reflectivity electromagnetic interference(EMI)shielding/high-temperature resistant infrared stealth material possesses a critical significance in the field of military.Hence,a hierarchical polyimide(PI)nonwoven fabric is fabricated by alkali treatment,in-situ growth of magnetic particles and"self-activated"electroless Ag plating process.Especially,the hierarchical impedance matching can be constructed by systematically assembling Fe_(3)O_(4)/Ag-loaded PI nonwoven fabric(PFA)and pure Ag-coated PI nonwoven fabric(PA),endowing it with an ultralowreflectivity EMI shielding performance.In addition,thermal insulation of fluffy three-dimensional(3D)space structure in PFA and low infrared emissivity of PA originated from Ag plating bring an excellent infrared stealth performance.More importantly,the strong bonding interaction between Fe_(3)O_(4),Ag,and PI fiber improves thermal stability in EMI shielding and high-temperature resistant infrared stealth performance.Such excellent comprehensive performance makes it promising for military tents to protect internal equipment from electromagnetic interference stemmed from adjacent equipment and/or enemy,and inhibit external infrared detection.展开更多
High-temperature stealth is vital for enhancing the concealment,survivability,and longevity of critical assets.However,achieving stealth across multiple infrared bands—particularly in the short-wave infrared(SWIR)ban...High-temperature stealth is vital for enhancing the concealment,survivability,and longevity of critical assets.However,achieving stealth across multiple infrared bands—particularly in the short-wave infrared(SWIR)band—along with microwave stealth and efficient thermal management at high temperatures,remains a significant challenge.Here,we propose a strategy that integrates an IR-selective emitter(Mo/Si multilayer films)and a microwave metasurface(TiB2–Al2O3–TiB2)to enable multi-infrared band stealth,encompassing mid-wave infrared(MWIR),long-wave infrared(LWIR),and SWIR bands,and microwave(X-band)stealth at 700℃,with simultaneous radiative cooling in non-atmospheric window(5–8μm).At 700℃,the device exhibits low emissivity of 0.38/0.44/0.60 in the MWIR/LWIR/SWIR bands,reflection loss below−3 dB in the X-band(9.6–12 GHz),and high emissivity of 0.82 in 5–8μm range—corresponding to a cooling power of 9.57 kW m^(−2).Moreover,under an input power of 17.3 kW m^(−2)—equivalent to the aerodynamic heating at Mach 2.2—the device demonstrates a temperature reduction of 72.4℃ compared to a conventional low-emissivity molybdenum surface at high temperatures.This work provides comprehensive guidance on high-temperature stealth design,with far-reaching implications for multispectral information processing and thermal management in extreme high-temperature environments.展开更多
The resource-intensive,high-fidelity infrared signature simulations and Radar CrossSection(RCS)calculations limit the integrated optimization of Unmanned Combat Aerial Vehicles(UCAVs)in response to escalating threats ...The resource-intensive,high-fidelity infrared signature simulations and Radar CrossSection(RCS)calculations limit the integrated optimization of Unmanned Combat Aerial Vehicles(UCAVs)in response to escalating threats from joint detection systems.To this end,we present a sample-efficient framework to advance the optimization efficiency of UCAV's exhaust system,focusing on both the stealth characteristics evaluation and the optimization process.A novel multi-fidelity stealth assessment method,powered by multi-fidelity neural network and local perceptive fields,has been developed to fuse different fidelity information from infrared radiation signature and RCS values,respectively.Results demonstrate that the method can achieve relatively high accuracy based on a small set of high-fidelity data.Furthermore,this data fusion method is integrated into a multi-objective Bayesian optimization framework.Employing a Gaussian process regression model and the EHVI acquisition function,the framework effectively explores the stealth objective space,achieving a 15.21%hypervolume indicator increase with fewer optimization iterations compared to NSGA-Ⅱ.Results show that the optimized nozzle significantly reduces both the infrared signature and RCS compared to the baseline configuration.The proposed framework offers a practical and efficient approach for optimizing the integrated stealth performance of UCAVs.展开更多
Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate...Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.展开更多
To address the severe electromagnetic(EM)pollution and thermal exhaustion issues in modern electronics,C@Mn_(x)O_(y) foams were first reported as an advanced multifunctional filler with superior microwave absorption,R...To address the severe electromagnetic(EM)pollution and thermal exhaustion issues in modern electronics,C@Mn_(x)O_(y) foams were first reported as an advanced multifunctional filler with superior microwave absorption,Radar wave stealth,and thermal dissipation.They were synthesized using a simple one-step annealing route,in which PVP and in-situ generated gas bubbles play a crucial role in the foam formation.Our results show that the C@Mn_(x)O_(y) foams possess excellent electrical insulation and a large thermal conductivity of 3.58 W(m K)^(–1) at a low load of 5 wt.%.Also,they exhibit prominent microwave absorption capabilities(MWACs)with a strong absorption(–46.03 dB)and a wide bandwidth(11.04 GHz)in a low load(30 wt.%).When they are then used as a patch,the wideband Radar cross-section can be effectively reduced by up to 41.34 dB m^(2).This performance outperforms most other heterostructures.Furthermore,the mechanism of dielectric loss and thermal transfer at the atomic level is revealed by the First-principle calculations of the density of states(DOS)and the phonon density of states(PDOS).The combination of C,MnO,and Mn_(3)O_(4) disrupts local microstructure symmetry and induces extra electrical dipoles at the heterointerfaces,benefiting the enhanced MWACs of C@Mn_(x)O_(y) foams along with defect polarization and multiple scattering.Their enhanced TC could be credited to the co-transmission of low phonon-boundary/phonon-defect scattering and multiple-frequency phonons from C,MnO,and Mn_(3)O_(4).Overall,the C@Mn_(x)O_(y) foams are highly promising for application in EM protection,absorption,and thermal management.What is more,this study provides a theoretical guide for designing heterostructures as effective microwave absorbing and thermally conductive materials used in modern electronics.展开更多
Manipulation of electromagnetic waves is essential to various microwave applications,and absorbing devices composed of low-pressure gas discharge tubes and radar-absorbing materials(RAM)can bring new solutions to broa...Manipulation of electromagnetic waves is essential to various microwave applications,and absorbing devices composed of low-pressure gas discharge tubes and radar-absorbing materials(RAM)can bring new solutions to broadband electromagnetic stealth.The microwave transmission method is used to measure the physical parameters of the plasma unit.The designed structure exhibits superior absorption performance and radar cross-section(RCS)reduction capability in the 2–18 GHz band,with unique absorption advantage in the S and C frequency bands.It is found that the combination of the plasma and the RAM can significantly broaden the absorption frequency band and improve the absorption performance with excellent synergistic stealth capability.Experimental and simulation results present that broadband,wide-angle,tunable electromagnetic wave absorption and RCS reduction can be achieved by adjusting the spatial layout of the combined plasma layer and the type of RAMs,which creates opportunities for microwave transmission and selective stealth of equipment.Therefore,the wave manipulation by combined plasma array and RAM provides a valuable reference for developing numerous applications,including radar antenna stealth,spatial filter,and high power microwave shielding.展开更多
This report studied on pharmaceutical characteristics of the stealth liposome containing dau-norubicin (DNR). The shape, size, entrapment efficiency and stability of the daunorubicin stealth liposomes (DNRSL) were exa...This report studied on pharmaceutical characteristics of the stealth liposome containing dau-norubicin (DNR). The shape, size, entrapment efficiency and stability of the daunorubicin stealth liposomes (DNRSL) were examined. Visible spectrophotometry and the HPLC method were established for determination of the DNR in the DNRSL. The release of DNR from DNRSL in HBS (pH 7.5) and rat serum at 37 oC were examined. The results showed that the DNRSL had high entrapment efficiency (>85%), small size and slow release.展开更多
Abstract Based on computational fluid dynamics （CFD） method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerody- namic/stealth has been estab...Abstract Based on computational fluid dynamics （CFD） method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerody- namic/stealth has been established for helicopter rotor. The developed integration design method is composed of three modules： integrated grids generation （the moving-embedded grids for CFD sol- ver and the blade grids for radar cross section （RCS） solver are generated by solving Poisson equa- tions and folding approach）, aerodynamic/stealth solver （the aerodynamic characteristics are simulated by CFD method based upon NavieStokes equations and Spalart-Allmaras （S-A） tur- bulence model）, and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics （PO）, equivalent currents （MEC） and quasi-stationary （MQS）, and integrated optimization analysis （based upon the surrogate model optimization technique with full factorial design （FFD） and radial basis function （RBF）, an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted. Firstly, the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out, then timfrequency domain grayscale with strong scattering regions of rotor have been given. Meanwhile, the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed. Furthermore, by choosing suitable object function and constraint condition, the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last.展开更多
基金the financial support from China Postdoctoral Science Foundation(2024M760348)National Natural Science Foundation of China(52373077)。
文摘Designing and preparing a compatible electromagnetic interference(EMI)shielding,radar and infrared stealth material exhibits significant prospect in the military field.Hence,a novel conductive/magnetic polyimide-based nonwoven fabric(PFN_y)is prepared by alkali treatment,Fe~(3+)ion exchange,thermal reduction,and electroless nickel(Ni)plating process.Its impedance/insulation characteristics can be easily adjusted by controlling the in situ growth of Fe_(3)O_(4) and electroless nickel plating.Subsequently,a new strategy of constructing hierarchical dual-gradient impedance/insulation structure is implemented to achieve EMI shielding,radar and infrared stealth via stacking PFN_y with gradually decreased impedance/insulation characteristics from top to bottom.The formation of impedance matching gradient structure promotes effective introduction and dissipation of electromagnetic waves,endowing the composite with outstanding EMI shielding and radar stealth performance.Meanwhile,the construction of thermal insulation gradient structure can effectively inhibit thermal radiation from target,bringing an excellent infrared stealth performance.Importantly,the strong interfacial interactions between Fe_(3)O_(4),Ni and polyimide fiber accelerate PFNy to resist the stresses originated from high-temperature heat source,achieving a compatible high-temperature resistant radar/infrared stealth performance.Such excellent comprehensive properties endow it with a great potential in high-temperature military camouflage applications against enemy radar and infrared detection.
基金supported by the National Natural Science Foundation of China(Nos.52373077,52003106,52233006,and 52161135302)the Research Foundation Flanders(No.G0F2322N)+1 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX23_1236)the Innovation Program of Shanghai Municipal Education Commission(No.2021-01-07-00-03-E00108).
文摘Designing and manufacturing compatible multi-band stealth materials remains a great challenge. In this work, a silver-metalized polyimide photochromic composite foam is successfully fabricated by self-activating electroless silver-plating on the surface of the polyimide skeleton and followed by applying a photochromic coating on the upper surface. The effective loading of silver nanoparticles facilitates the rational construction of a conductive network in foam, improving the efficient dissipation of incident electromagnetic waves. In addition, the interconnected conductive network successfully endows it with an excellent Joule heating capability, which can be employed to effectively remove ice and/or mitigate the impact of water vapor on radar stealth performance in cold and wet weather. Besides, the low emissivity silver plating combined with superior thermal insulation of foam enables the material with excellent infrared stealth performance. Moreover, the modulation of self-adaptive photochromic coating brings a prominent visual stealth performance under different sunlight backgrounds. As a result, such excellent radar and infrared stealth performance combined with the adaptive color-switching capability provides the foam with great potential for preparing compatible multi-band materials.
基金supported by the National Natural Science Foundation of China(Nos.52071053,U1704253,and 52103334).
文摘Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.
基金financial support from the National Nature Science Foundation of China(No.52273247)the National Science and Technology Major Project of China(J2019-VI-0017-0132).
文摘Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR cloaking mechanisms and functional integration limitations.Here,we propose a multiscale hierarchical structure design,integrating wrinkled MXene IR shielding layer and flexible Fe_(3)O_(4)@C/PDMS microwave absorption layer.The top wrinkled MXene layer induces the intensive diffuse reflection effect,shielding IR radiation signals while allowing microwave to pass through.Meanwhile,the permeable microwaves are assimilated into the bottom Fe_(3)O_(4)@C/PDMS layer via strong magneto-electric synergy.Through theoretical and experimental optimization,the assembled stealth devices realize a near-perfect stealth capability in both X-band(8–12 GHz)and long-wave infrared(8–14μm)wavelength ranges.Specifically,it delivers a radar cross-section reduction of−20 dB m^(2),a large apparent temperature modulation range(ΔT=70℃),and a low average IR emissivity of 0.35.Additionally,the optimal device demonstrates exceptional curved surface conformability,self-cleaning capability(contact angle≈129°),and abrasion resistance(recovery time≈5 s).This design strategy promotes the development of multispectral stealth technology and reinforces its applicability and durability in complex and hostile environments.
基金supported by the Natural Science Foundation of Hunan Province(No.2024JJ5419)the Hunan Provincial Key Research and Development Plan Project in 2024(No.2024JK2074)+1 种基金the Natural Science Foundation of Changsha(No.2023-197)the Open project of the Key Laboratory of digital flavor research of Hunan China Tobacco Industry Co.,Ltd(No.202143000834024).
文摘Multifunctional compatible stealth materials have emerged as the focal point of contemporary protection technology research and vanadium-based nanomaterials play a pivotal role in the development of advanced stealth materials.Here,a compatible stealth aerogel is successfully synthesized by employing mixed-valence decavanadate as the vanadium oxide(VO_(x))molecular model.Ultralight{V^(Ⅳ)VV_(9)}/MXene aerogel(0.0429 g cm^(-3))exhibits exceptional radar stealth performance with a minimal reflection loss(RL_(min))of−57.74 dB(99.9998%EMW absorption)and a significantly superior radar cross section reduction value of 26.77 dB m2.The aerogel’s exceptional properties,including a low infrared(IR)emissivity(0.479)and a low thermal conductivity of(32.30 mW m^(-1)K^(-1)),are crucial for enabling compatibility with IR and thermal stealth technologies.The presence of a mixed-valence polyoxovanadate cluster leads to an increase in the Schottky barrier and enhances magnetic properties,consequently boosting interfacial polarization and contributing to magnetic losses during electromagnetic wave(EMW)absorption.Consequently,altering the number of valence electrons significantly enhances the compatible stealth capabilities.These findings contribute significantly to our comprehension of how microstructure impacts EMW absorption processes and provide a basis for further research into the development of VO_(x)-based compatible stealth materials.
基金supported by the Key Research and Development Program of Sichuan Province(Grant No.2023ZHCG0050)the Fundamental Research Funds for the Central Universities of China(Grant No.2682024QZ006 and 2682024ZTPY042)the Analytic and Testing Center of Southwest Jiaotong University.
文摘As modern communication and detection technologies advance at a swift pace,multifunctional electromagnetic interference(EMI)shielding materials with active/positive infrared stealth,hydrophobicity,and electric-thermal conversion ability have received extensive attention.Meeting the aforesaid requirements simultaneously remains a huge challenge.In this research,the melamine foam(MF)/polypyrrole(PPy)nanowire arrays(MF@PPy)were fabricated via one-step electrochemical polymerization.The hierarchical MF@PPy foam was composed of three-dimensional PPy micro-skeleton and ordered PPy nanowire arrays.Due to the upwardly grown PPy nanowire arrays,the MF@PPy foam possessed good hydrophobicity ability with a water contact angle of 142.00°and outstanding stability under various harsh environments.Meanwhile,the MF@PPy foam showed excellent thermal insulation property on account of the low thermal conductivity and elongated ligament characteristic of PPy nanowire arrays.Furthermore,taking advantage of the high conductivity(128.2 S m^(-1)),the MF@PPy foam exhibited rapid Joule heating under 3 V,resulting in dynamic infrared stealth and thermal camouflage effects.More importantly,the MF@PPy foam exhibited remarkable EMI shielding effectiveness values of 55.77 dB and 19,928.57 dB cm^(2)g^(-1).Strong EMI shielding was put down to the hierarchically porous PPy structure,which offered outstanding impedance matching,conduction loss,and multiple attenuations.This innovative approach provides significant insights to the development of advanced multifunctional EMI shielding foams by constructing PPy nanowire arrays,showing great applications in both military and civilian fields.
基金financially supported by the National Nat-ural Science Foundation of China(Nos.92473102,62004141,and 52202045)the Knowledge Innovation Program of Wuhan-Shuguang(Nos.2023010201020243,and 2023010201020255)+4 种基金the Major Program(JD)of Hubei Province(No.2023BAA009)the Shenzhen Science and Technology Program(No.JCYJ20240813175906008)the Fundamental Research Funds for the Central Universities(Nos.2042023kf0112,and 2042022kf1028)the Open Fund of Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration(Wuhan University)(Nos.EMPI2024014,EMPI2024021,and EMPI2023027)the China Scholarship Council(No.202206275005).
文摘Gallium oxide(Ga_(2)O_(3))is an ultra-wide bandgap semiconductor with excellent potential for high-power and ultraviolet optoelectronic device applications.High-performance Ga_(2)O_(3)-based high-power devices rely heavily on precise processing,especially in wafer dicing.Laser stealth dicing(LSD)is an innova-tive laser technology that utilizes a focused laser to create subsurface modifications in the wafer without surface damage.LSD has broad application prospects in the field of semiconductor precision processing.In this work,the idea of achieving high-quality dicing ofβ-Ga_(2)O_(3) wafers via LSD was proposed.A com-bination of atomistic simulations and experiments was used to understand the underlying mechanism of LSD ofβ-Ga_(2)O_(3) wafers.On the one hand,the laser loading and fracture process ofβ-Ga_(2)O_(3) wafers were simulated using molecular dynamics(MD)methods as well as a machine learning potential.The effects of single-pulse energy on LSD were analyzed through the lattice residual pressure,the final total energy of the system,the internal atomic strain,and the maximum stress value during uniaxial tension.On the other hand,based on the MD simulations,LSD was successfully performed onβ-Ga_(2)O_(3) wafers along three main crystal planes in the laboratory,resulting in good surface quality.This work not only provides profound optimization strategies for the LSD process ofβ-Ga_(2)O_(3),establishing the foundation for high-quality dicing ofβ-Ga_(2)O_(3) wafers,but also verifies the accuracy of MD simulations in predict-ing trends related to the LSD,offering a potential approach for high-quality dicing of other materials in future research.
基金the funding provided by the National Natural Science Foundation of China(Nos.62205038,62031006,62425106)the Natural Science Foundation of Chongqing Municipality of China(Nos.CSTB2023NSCQ-MSX0028,CSTB2022NSCQ-LZX0015)the Opening Subject of State Key Laboratory of Millimeter Waves of China(No.K202419)。
文摘Metasurfaces,which are two-dimensional arrays of subwavelength elements,enable versatile control of electromagnetic waves,thereby paving the way for advancements in electromagnetic stealth.Electromagnetic stealth aims to diminish object visibility to radar or other sensors by minimizing their reflection,scattering,or emission of electromagnetic waves.This paper reviews the latest works in microwave electromagnetic stealth devices utilizing metasurfaces,including absorbing,scattering,cloaking and multifunctional stealth techniques.A comprehensive analysis and characterization of these stealth metasurface based devices are presented,focusing on their working principles,performance characteristics,and the associated challenges.Additionally,we explore prospects and opportunities for further research.This paper offers a thorough and upto-date survey of the current status and future directions of this emerging field.
基金the National Natural Science Foundation of China(Nos.52373073,52073091,52303083,22171086)the Shanghai Pujiang Program(No.22PJ1402500)the Fundamental Research Funds for the Central Universities(No.JKD01231701).
文摘The investigation of absorption-led shielding mechanisms has now made practical progress as a result of the concept of green EM shielding.The extant studies primarily concentrate on the introduction of mag-netic particles into the system,with the objective of enhancing the absorption rate(A)through dielectric-magnetic modulation for absorption-led electromagnetic shielding.In contrast,this paper presents a novel approach whereby PVA,glycerol,and MXene are combined into an organohydrogel(PMG)with oriented pores.This results in the creation of a non-magnetic medium that exhibits high absorption loss in mul-tiple bands,thereby establishing a novel shielding system.The PMG20-3 organohydrogel(0.78 wt%MX-ene)has a shielding performance in the X-band of 42.34 dB(A/R=1).In the terahertz band,the organic hydrogel gel exhibits an absorption rate of 99.9%,a performance that exceeds that of the majority of previously reported systems.The PMG gel displays remarkable flexibility and strength,with a hysteresis return line that remains stable under 1000 compression cycles.Additionally,it offers versatile sensing capabilities and infrared stealth.The findings of this study offer novel insights that may facilitate the accelerated utilization of innovative multifunctional and environmentally conscious electromagnetic in-terference(EMI)shielding materials.
基金support from the National Natural Science Foundation of China(52373077,52003106,52103074,52233006,52161135302)the Research Foundation Flanders(G0F2322N)Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-03-E00108).
文摘Designing and fabricating a compatible low-reflectivity electromagnetic interference(EMI)shielding/high-temperature resistant infrared stealth material possesses a critical significance in the field of military.Hence,a hierarchical polyimide(PI)nonwoven fabric is fabricated by alkali treatment,in-situ growth of magnetic particles and"self-activated"electroless Ag plating process.Especially,the hierarchical impedance matching can be constructed by systematically assembling Fe_(3)O_(4)/Ag-loaded PI nonwoven fabric(PFA)and pure Ag-coated PI nonwoven fabric(PA),endowing it with an ultralowreflectivity EMI shielding performance.In addition,thermal insulation of fluffy three-dimensional(3D)space structure in PFA and low infrared emissivity of PA originated from Ag plating bring an excellent infrared stealth performance.More importantly,the strong bonding interaction between Fe_(3)O_(4),Ag,and PI fiber improves thermal stability in EMI shielding and high-temperature resistant infrared stealth performance.Such excellent comprehensive performance makes it promising for military tents to protect internal equipment from electromagnetic interference stemmed from adjacent equipment and/or enemy,and inhibit external infrared detection.
基金supported by National Key Research and Development Program of China(Grant No.2024YFA1210500)National Natural Science Foundation of China(Grant Nos.U2341225 and 62375242)+1 种基金Sichuan Science and Technology Program(2025YFHZ0297)Postdoctoral Fellowship Program of CPSF(Grant No.GZB20240647).
文摘High-temperature stealth is vital for enhancing the concealment,survivability,and longevity of critical assets.However,achieving stealth across multiple infrared bands—particularly in the short-wave infrared(SWIR)band—along with microwave stealth and efficient thermal management at high temperatures,remains a significant challenge.Here,we propose a strategy that integrates an IR-selective emitter(Mo/Si multilayer films)and a microwave metasurface(TiB2–Al2O3–TiB2)to enable multi-infrared band stealth,encompassing mid-wave infrared(MWIR),long-wave infrared(LWIR),and SWIR bands,and microwave(X-band)stealth at 700℃,with simultaneous radiative cooling in non-atmospheric window(5–8μm).At 700℃,the device exhibits low emissivity of 0.38/0.44/0.60 in the MWIR/LWIR/SWIR bands,reflection loss below−3 dB in the X-band(9.6–12 GHz),and high emissivity of 0.82 in 5–8μm range—corresponding to a cooling power of 9.57 kW m^(−2).Moreover,under an input power of 17.3 kW m^(−2)—equivalent to the aerodynamic heating at Mach 2.2—the device demonstrates a temperature reduction of 72.4℃ compared to a conventional low-emissivity molybdenum surface at high temperatures.This work provides comprehensive guidance on high-temperature stealth design,with far-reaching implications for multispectral information processing and thermal management in extreme high-temperature environments.
基金supported by the National Natural Science Foundation of China(No.12102356)。
文摘The resource-intensive,high-fidelity infrared signature simulations and Radar CrossSection(RCS)calculations limit the integrated optimization of Unmanned Combat Aerial Vehicles(UCAVs)in response to escalating threats from joint detection systems.To this end,we present a sample-efficient framework to advance the optimization efficiency of UCAV's exhaust system,focusing on both the stealth characteristics evaluation and the optimization process.A novel multi-fidelity stealth assessment method,powered by multi-fidelity neural network and local perceptive fields,has been developed to fuse different fidelity information from infrared radiation signature and RCS values,respectively.Results demonstrate that the method can achieve relatively high accuracy based on a small set of high-fidelity data.Furthermore,this data fusion method is integrated into a multi-objective Bayesian optimization framework.Employing a Gaussian process regression model and the EHVI acquisition function,the framework effectively explores the stealth objective space,achieving a 15.21%hypervolume indicator increase with fewer optimization iterations compared to NSGA-Ⅱ.Results show that the optimized nozzle significantly reduces both the infrared signature and RCS compared to the baseline configuration.The proposed framework offers a practical and efficient approach for optimizing the integrated stealth performance of UCAVs.
基金supported by the National Natural Science Foundation of China(No.22265021)the Aeronautical Science Foundation of China(No.2020Z056056003)。
文摘Considering the challenges posed by severe electromagnetic wave pollution and escalating international tensions,there is a critical need to develop advanced electromagnetic wave absorbing(EMWA)materials that integrate radar stealth and thermal insulation capabilities.In this study,we have synthesized three-dimensional(3D)porous composites comprising V_(2)O_(3) nanoparticles embedded in Juncus effusus cellulose-derived carbon aerogels(VCA)using a self-templating method followed by high-temperature pyrolysis.The V_(2)O_(3) nanoparticles possess a 3D V-V framework and a relatively narrow bandgap,facilitating the Mott transition for enhanced conductivity.Furthermore,their uniform dispersion on hollow carbon tubes of Juncus effusus promotes efficient electron transfer and creates numerous heterogeneous interfaces.Consequently,VCA-2 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.92 dB at a matching thickness of 2.0mm and a maximum effective absorption bandwidth of 8.24 GHz at a thickness of 2.44mm,covering nearly half of the tested frequency range.Additionally,the radar cross-section reduction reaches a peak value of 29.40 dB m^(2),underscoring the excellent radar stealth capabilities of the material.In summary,VCA exhibits exceptional EMWA,radar stealth,and thermal insulation properties,highlighting its potential for multifunctional applications in EMWA material development.
基金financially supported by the National Natural Science Foundation of China(No.52073260)the Zhejiang Provincial Natural Science Foundation of China(Nos.LGG21E020002 and LZ24E020004)the Major industrial projects of Jinhua City(No.2024A11011).
文摘To address the severe electromagnetic(EM)pollution and thermal exhaustion issues in modern electronics,C@Mn_(x)O_(y) foams were first reported as an advanced multifunctional filler with superior microwave absorption,Radar wave stealth,and thermal dissipation.They were synthesized using a simple one-step annealing route,in which PVP and in-situ generated gas bubbles play a crucial role in the foam formation.Our results show that the C@Mn_(x)O_(y) foams possess excellent electrical insulation and a large thermal conductivity of 3.58 W(m K)^(–1) at a low load of 5 wt.%.Also,they exhibit prominent microwave absorption capabilities(MWACs)with a strong absorption(–46.03 dB)and a wide bandwidth(11.04 GHz)in a low load(30 wt.%).When they are then used as a patch,the wideband Radar cross-section can be effectively reduced by up to 41.34 dB m^(2).This performance outperforms most other heterostructures.Furthermore,the mechanism of dielectric loss and thermal transfer at the atomic level is revealed by the First-principle calculations of the density of states(DOS)and the phonon density of states(PDOS).The combination of C,MnO,and Mn_(3)O_(4) disrupts local microstructure symmetry and induces extra electrical dipoles at the heterointerfaces,benefiting the enhanced MWACs of C@Mn_(x)O_(y) foams along with defect polarization and multiple scattering.Their enhanced TC could be credited to the co-transmission of low phonon-boundary/phonon-defect scattering and multiple-frequency phonons from C,MnO,and Mn_(3)O_(4).Overall,the C@Mn_(x)O_(y) foams are highly promising for application in EM protection,absorption,and thermal management.What is more,this study provides a theoretical guide for designing heterostructures as effective microwave absorbing and thermally conductive materials used in modern electronics.
基金supported by National Natural Science Foundation of China(No.51907198)Natural Science Research Foundation of Anhui Province(No.1908085MF205)+1 种基金Director Fund of State Key Laboratory of Pulsed Power Laser Technology(Nos.SKL2021ZR07,SKL2021ZR06)China Postdoctoral Science Foundation(No.2021MD703944).
文摘Manipulation of electromagnetic waves is essential to various microwave applications,and absorbing devices composed of low-pressure gas discharge tubes and radar-absorbing materials(RAM)can bring new solutions to broadband electromagnetic stealth.The microwave transmission method is used to measure the physical parameters of the plasma unit.The designed structure exhibits superior absorption performance and radar cross-section(RCS)reduction capability in the 2–18 GHz band,with unique absorption advantage in the S and C frequency bands.It is found that the combination of the plasma and the RAM can significantly broaden the absorption frequency band and improve the absorption performance with excellent synergistic stealth capability.Experimental and simulation results present that broadband,wide-angle,tunable electromagnetic wave absorption and RCS reduction can be achieved by adjusting the spatial layout of the combined plasma layer and the type of RAMs,which creates opportunities for microwave transmission and selective stealth of equipment.Therefore,the wave manipulation by combined plasma array and RAM provides a valuable reference for developing numerous applications,including radar antenna stealth,spatial filter,and high power microwave shielding.
文摘This report studied on pharmaceutical characteristics of the stealth liposome containing dau-norubicin (DNR). The shape, size, entrapment efficiency and stability of the daunorubicin stealth liposomes (DNRSL) were examined. Visible spectrophotometry and the HPLC method were established for determination of the DNR in the DNRSL. The release of DNR from DNRSL in HBS (pH 7.5) and rat serum at 37 oC were examined. The results showed that the DNRSL had high entrapment efficiency (>85%), small size and slow release.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘Abstract Based on computational fluid dynamics （CFD） method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerody- namic/stealth has been established for helicopter rotor. The developed integration design method is composed of three modules： integrated grids generation （the moving-embedded grids for CFD sol- ver and the blade grids for radar cross section （RCS） solver are generated by solving Poisson equa- tions and folding approach）, aerodynamic/stealth solver （the aerodynamic characteristics are simulated by CFD method based upon NavieStokes equations and Spalart-Allmaras （S-A） tur- bulence model）, and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics （PO）, equivalent currents （MEC） and quasi-stationary （MQS）, and integrated optimization analysis （based upon the surrogate model optimization technique with full factorial design （FFD） and radial basis function （RBF）, an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted. Firstly, the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out, then timfrequency domain grayscale with strong scattering regions of rotor have been given. Meanwhile, the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed. Furthermore, by choosing suitable object function and constraint condition, the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last.
