As a hydrogen storage material,both AlH_(3)and LiNH_(2)possess a high hydrogen capacity.However,the dehydrogenated AlH_(3)can hardly absorb hydrogen under normal conditions,while LiNH_(2)will generate NH_(3)rather tha...As a hydrogen storage material,both AlH_(3)and LiNH_(2)possess a high hydrogen capacity.However,the dehydrogenated AlH_(3)can hardly absorb hydrogen under normal conditions,while LiNH_(2)will generate NH_(3)rather than H_(2)upon decomposition.In this work,we report thatthe combination of AlH_(3)and LiNH_(2)through simple ball milling leads to partial reversibility of the AlH_(3)-LiNH_(2)system and the suppression of NH_(3)liberation.The negatively charged H^(δ-)in AlH_(3)will react with the positively charged H^(δ+)in LiNH_(2)through a redox reaction to form Li_(2)NH,AlN,and H_(2)at 120-170℃.After dehydrogenation at above 270℃,Li_(3)AlN_(2)is generated,which is crucial for the reversibility of this system.The more the Li3AlN2generated,the better the reversibility of this system.The dehydrogenation capacity of AlH_(3)+2LiNH_(2)at the third cycle(3.0 wt%)is higher than that of AlH_(3)+LiNH_(2)(1.2 wt%)due to the generation of more Li3AlN2.The role of AIH_(3)/Al in the AlH_(3)-LiNH_(2)system is to fix the nitrogen into the form of AIN and Li_(3)AlN_(2)and thus suppress the liberation of NH_(3).Therefore,the synergy of AlH_(3)and LiNH_(2)leads to the reversibility of the Li-Al-NH system and the suppression of NH_(3).展开更多
BACKGROUND Posterior reversible encephalopathy syndrome(PRES)is a complex neurological disorder characterized by symptoms such as headaches,seizures,confusion,and visual disturbances.The pathophysiology of PRES involv...BACKGROUND Posterior reversible encephalopathy syndrome(PRES)is a complex neurological disorder characterized by symptoms such as headaches,seizures,confusion,and visual disturbances.The pathophysiology of PRES involves endothelial dysfunction,disrupted cerebral autoregulation,and resulting vasogenic edema.Hypertension and other factors that alter cerebral autoregulation are critical in its development.Corticosteroids,widely used for their anti-inflammatory and immunosuppressive properties,play a controversial role in PRES.AIM To elucidate the dual role of corticosteroids in the context of PRES by critically evaluating the existing literature.Specifically,it seeks to assess the results of PRES induced by corticosteroid therapy and the efficacy and safety of corticosteroids in the treatment of PRES.By synthesizing case reports and series,this review aims to provide a comprehensive understanding of the mechanisms,clinical presentations,and management strategies associated with corticosteroid-related PRES.METHODS The review was carried out according to the PRISMA guidelines.The databases searched included Science Direct,PubMed,and Hinari.The search strategy encompassed terms related to corticosteroids and PRES.Studies were included if they were peer-reviewed articles examining corticosteroids in PRES,excluding non-English publications,reviews,and editorials.Data on patient demographics,clinical characteristics,imaging findings,corticosteroid regimens,and outcomes were extracted.The risk of bias was evaluated using the Joanna Briggs Institute tool for case reports.RESULTS A total of 56 cases of PRES(66.1%women,33.9%men)potentially induced by corticosteroids and 14 cases in which corticosteroids were used to treat PRES were identified.Cases of PRES reportedly caused by corticosteroids showed a mean age of approximately 25.2 years,with seizures,headaches,hypertension,and visual disturbances being common clinical sequelae.Magnetic resonance findings typically revealed vasogenic edema in the bilateral parieto-occipital lobes.High-dose or prolonged corticosteroid therapy was a significant risk factor.On the contrary,in the treatment cases,corticosteroids were associated with positive outcomes,including resolution of vasogenic edema and stabilization of symptoms,particularly in patients with underlying inflammatory or autoimmune diseases.CONCLUSION Corticosteroids have a dual role in PRES,capable of both inducing and treating the condition.The current body of literature suggests that corticosteroids may play a greater role as a precipitating agent of PRES rather than treating.Corticosteroids may induce PRES through hypertension and subsequent increased cerebral blood flow and loss of autoregulation.Corticosteroids may aid in the management of PRES:(1)Enhancing endothelial stability;(2)Antiinflammatory properties;and(3)Improving blood-brain barrier integrity.Mechanisms which may reduce or mitigate vasogenic edema formation.展开更多
In this paper,we investigate a class of reversible dynamical systems in four dimensions.The spectrums of their linear operators at the equilibria are assumed to have a pair of positive and negative real eigenvalues an...In this paper,we investigate a class of reversible dynamical systems in four dimensions.The spectrums of their linear operators at the equilibria are assumed to have a pair of positive and negative real eigenvalues and a pair of purely imaginary eigenvalues for the small parameterμ>0,where these two real eigenvalues bifurcate from a double eigenvalue 0 forμ=0.It has been shown that this class of systems owns a generalized homoclinic solution with one hump at the center(a homoclinic solution exponentially approaching a periodic solution with a small amplitude).This paper gives a rigorous existence proof of two-hump solutions.These two humps are far away and are glued by the small oscillations in the middle if some appropriate free constants are activated.The obtained results are also applied to some classical systems.The ideas here may be used to study the existence of 2^(k)-hump solutions.展开更多
The authors study the bifurcation of homoclinic orbits from a degenerate homoclinic orbit in reversible system. The unperturbed system is assumed to have saddle-center type equilibrium whose stable and unstable manifo...The authors study the bifurcation of homoclinic orbits from a degenerate homoclinic orbit in reversible system. The unperturbed system is assumed to have saddle-center type equilibrium whose stable and unstable manifolds intersect in two-dimensional manifolds. A perturbation technique for the detection of symmetric and nonsymmetric homoctinic orbits near the primary homoclinic orbits is developed. Some known results are extended.展开更多
In this paper, a result on the persistence of lower dimensional invariant tori in Cd reversible systems is obtained under some conditions. The theorem is proved for any d which is larger than some constants.
This paper is concerned with the boundedness of solutions for second order differential equations x + f(x, t)x + g(x, t) = 0, which are neither dissipative nor conservative, and where the functions f and g are odd in ...This paper is concerned with the boundedness of solutions for second order differential equations x + f(x, t)x + g(x, t) = 0, which are neither dissipative nor conservative, and where the functions f and g are odd in x and even in t, which are 1-periodic in t, and the function g satisfies g(x,t/x+, as|x| - +. Using the KAM theory for reversible systems, the author proves the existence of invariant tori and thus the boundedness of all the solutions and the existence of quasiperiodic solutions and subharmonic solutions.展开更多
By using the Picard-Fuchs equation and the property of the Chebyshev space to the discontinuous differential system, we obtain an upper bound of the number of limit cycles for the nongeneric quadratic reversible syste...By using the Picard-Fuchs equation and the property of the Chebyshev space to the discontinuous differential system, we obtain an upper bound of the number of limit cycles for the nongeneric quadratic reversible system when it is perturbed inside all discontinuous polynomials with degree n.展开更多
For reversible systems of infinite dimension we prove an infinitely dimensional KAM theorem with an application to the network of weakly coupled oscillators of friction. The KAM theorem shows that there are many invar...For reversible systems of infinite dimension we prove an infinitely dimensional KAM theorem with an application to the network of weakly coupled oscillators of friction. The KAM theorem shows that there are many invariant tori of infinite dimension, and thus many almost periodic solutions, for the reversible systems.展开更多
We are concerned with the boundedness of all the solutions for second order differential equation $$\ddot x + f\left( x \right)\dot x + g\left( x \right) = e\left( t \right),$$ , wheref(x) andg(x) are odd, e( t) is od...We are concerned with the boundedness of all the solutions for second order differential equation $$\ddot x + f\left( x \right)\dot x + g\left( x \right) = e\left( t \right),$$ , wheref(x) andg(x) are odd, e( t) is odd and 1-periodic, andg(x) satisfies $$Sign \left( x \right) \cdot g\left( x \right) \to + \infty ,\frac{{g\left( x \right)}}{x} \to 0,as\left| x \right| \to + \infty .$$展开更多
Reversible system following Hamiltonian system turns out to be another type of equation which has aroused wide interest in recent years. One open problem is whether the celebrated KAM theory and Nekhoroshev method can...Reversible system following Hamiltonian system turns out to be another type of equation which has aroused wide interest in recent years. One open problem is whether the celebrated KAM theory and Nekhoroshev method can be extended to reversible system. As showed in [5], there exist KAM tori in reversible system. In this paper, we give a preliminary discussion on whether there is Nekhoroshev type result in reversible system. In particular, we try to apply this method to the reducibility of a type of common reversible system.展开更多
To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invari...To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.展开更多
The rapid transmission of multimedia information has been achieved mainly by recent advancements in the Internet’s speed and information technology.In spite of this,advancements in technology have resulted in breache...The rapid transmission of multimedia information has been achieved mainly by recent advancements in the Internet’s speed and information technology.In spite of this,advancements in technology have resulted in breaches of privacy and data security.When it comes to protecting private information in today’s Internet era,digital steganography is vital.Many academics are interested in digital video because it has a great capability for concealing important data.There have been a vast number of video steganography solutions developed lately to guard against the theft of confidential data.The visual imperceptibility,robustness,and embedding capacity of these approaches are all challenges that must be addressed.In this paper,a novel solution to reversible video steganography based on Discrete Wavelet Transform(DWT)and Quick Response(QR)codes is proposed to address these concerns.In order to increase the security level of the suggested method,an enhanced ElGamal cryptosystem has also been proposed.Prior to the embedding stage,the suggested method uses the modified ElGamal algorithm to encrypt secret QR codes.Concurrently,it applies two-dimensional DWT on the Y-component of each video frame resulting in Approximation(LL),Horizontal(LH),Vertical(HL),and Diagonal(HH)sub-bands.Then,the encrypted Low(L),Medium(M),Quantile(Q),and High(H)QR codes are embedded into the HL sub-band,HHsub-band,U-component,and V-component of video frames,respectively,using the Least Significant Bit(LSB)technique.As a consequence of extensive testing of the approach,it was shown to be very secure and highly invisible,as well as highly resistant to attacks from Salt&Pepper,Gaussian,Poisson,and Speckle noises,which has an average Structural Similarity Index(SSIM)of more than 0.91.Aside from visual imperceptibility,the suggested method exceeds current methods in terms of Peak Signal-to-Noise Ratio(PSNR)average of 52.143 dB,and embedding capacity 1 bpp.展开更多
In this paper, using the KAM theorem of reversible systems, we obtain the boundednessof solutions, the existence of quasi-periodic solutions and subharmonic solutions for the non-linear differential equations of the s...In this paper, using the KAM theorem of reversible systems, we obtain the boundednessof solutions, the existence of quasi-periodic solutions and subharmonic solutions for the non-linear differential equations of the second order which is neither conservative nor dissipative.展开更多
A new type of diacetylene monomer which includes a biphenylcarboxylic acid group as its head group is synthesized.Polymerization was performed after monomer form spherical vesicle by self-assembly in the water.The pol...A new type of diacetylene monomer which includes a biphenylcarboxylic acid group as its head group is synthesized.Polymerization was performed after monomer form spherical vesicle by self-assembly in the water.The polydiacetylene displayed completely thermochromic color change in the range of 20-95℃ owing to the presence of strong π-π interaction caused by biphenyl group and hydrogen bonding between head group.展开更多
Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage p...Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.展开更多
Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells(R-SOCs).Herein,we re-port an A-site high-entropy engineered perovskite oxide,La_(0.2)Pr_(0.2)Nd_(0.2)Ba_(0.2)Sr_(...Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells(R-SOCs).Herein,we re-port an A-site high-entropy engineered perovskite oxide,La_(0.2)Pr_(0.2)Nd_(0.2)Ba_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF),and its electrocatalytic activity and stability property are systematically probed for tubular R-SOCs.The HE-LSCF air electrode exhibits excellent oxygen reduction reac-tion(ORR)activity with a low polarization resistance of 0.042Ω·cm^(2)at 700℃,which is much lower than that of La0.6Sr0.4Co_(0.8)Fe_(0.2)O_(3−δ)(LSCF),indicating the excellent catalytic activity of HE-LSCF.Meanwhile,the tubular R-SOCs with HE-LSCF shows a high peak power density of 1.18 W·cm^(−2)in the fuel cell mode and a promising electrolysis current density of−0.52 A·cm^(−2)at 1.5 V in the electrolysis mode with H_(2)(~10%H_(2)O)atmosphere at 700℃.More importantly,the tubular R-SOCs with HE-LSCF shows favorable stability under 180 h reversible cycling test.Our results show the high-entropy design can significantly enhance the activity and robustness of LSCF electrode for tubular R-SOCs.展开更多
Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots.Compared to active sensing devices,passive piezoelectric and triboelectric tactile sensors c...Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots.Compared to active sensing devices,passive piezoelectric and triboelectric tactile sensors consume less power,but lack the capability to resolve static stimuli.Here,we address this issue by utilizing the unique polarization chemistry of conjugated polymers for the first time and propose a new type of bioinspired,passive,and bio-friendly tactile sensors for resolving both static and dynamic stimuli.Specifically,to emulate the polarization process of natural sensory cells,conjugated polymers(including poly(3,4-ethylenedioxythiophen e):poly(styrenesulfonate),polyaniline,or polypyrrole)are controllably polarized into two opposite states to create artificial potential differences.The controllable and reversible polarization process of the conjugated polymers is fully in situ characterized.Then,a micro-structured ionic electrolyte is employed to imitate the natural ion channels and to encode external touch stimulations into the variation in potential difference outputs.Compared with the currently existing tactile sensing devices,the developed tactile sensors feature distinct characteristics including fully organic composition,high sensitivity(up to 773 mV N^(−1)),ultralow power consumption(nW),as well as superior bio-friendliness.As demonstrations,both single point tactile perception(surface texture perception and material property perception)and two-dimensional tactile recognitions(shape or profile perception)with high accuracy are successfully realized using self-defined machine learning algorithms.This tactile sensing concept innovation based on the polarization chemistry of conjugated polymers opens up a new path to create robotic tactile sensors and prosthetic electronic skins.展开更多
Electrochromic(EC)smart windows utilizing a reversible metal electrodeposition device(RMED)offer a compelling alternative for dynamically regulating transmissions of optical and thermal energy.An EC device(ECD)is cons...Electrochromic(EC)smart windows utilizing a reversible metal electrodeposition device(RMED)offer a compelling alternative for dynamically regulating transmissions of optical and thermal energy.An EC device(ECD)is constructed by reversible metal electrodeposition(RME)of Bi/Cu on WO_(3)·xH_(2)O film electrodeposited onto fluorine-doped tin oxide(FTO)transparent conductive glass.The electrolyte consists of CuCl_(2),BiCl_(3),KCl and HCl aqueous solution,supplying necessary components for both electrochemical and electrodeposition processes.The ECD shows ability to rapidly transition between colorless and black states,which achieves a large optical modulation of 77.0%at 570 nm.In the black state,the ECD exhibits a near-zero transmittance in the wavelength range of 400-1100 nm while maintaining 96.6%of its initial optical modulation after coloration/bleaching cycling of 60000 s,exhibiting good cyclic stability.This RMED has relatively high stability under open-circuit voltage and also possesses excellent heat insulation performance.The results offer a solution to overcome the poor cyclic stability of RMEDs and improve the optical modulation of ECDs.展开更多
With the rapid expansion of multimedia data,protecting digital information has become increasingly critical.Reversible data hiding offers an effective solution by allowing sensitive information to be embedded in multi...With the rapid expansion of multimedia data,protecting digital information has become increasingly critical.Reversible data hiding offers an effective solution by allowing sensitive information to be embedded in multimedia files while enabling full recovery of the original data after extraction.Audio,as a vital medium in communication,entertainment,and information sharing,demands the same level of security as images.However,embedding data in encrypted audio poses unique challenges due to the trade-offs between security,data integrity,and embedding capacity.This paper presents a novel interpolation-based reversible data hiding algorithm for encrypted audio that achieves scalable embedding capacity.By increasing sample density through interpolation,embedding opportunities are significantly enhanced while maintaining encryption throughout the process.The method further integrates multiple most significant bit(multi-MSB)prediction and Huffman coding to optimize compression and embedding efficiency.Experimental results on standard audio datasets demonstrate the proposed algorithm’s ability to embed up to 12.47 bits per sample with over 9.26 bits per sample available for pure embedding capacity,while preserving full reversibility.These results confirm the method’s suitability for secure applications that demand high embedding capacity and perfect reconstruction of original audio.This work advances reversible data hiding in encrypted audio by offering a secure,efficient,and fully reversible data hiding framework.展开更多
Purely organic room-temperature phosphorescence(RTP)is current hotspot in the research fields of chemistry,biology,materials etc.Herein,we report that photo-thermal double response reversible ultralong RTP flexible el...Purely organic room-temperature phosphorescence(RTP)is current hotspot in the research fields of chemistry,biology,materials etc.Herein,we report that photo-thermal double response reversible ultralong RTP flexible elastic material with multicolor delayed fluorescence,which is constructed by 4-biphenylboronic acid(BOH),polyethylene glycol,2,2-bis(hydroxymethyl)propionic acid,isophorone diamine and isophorone diisocyanate copolymer.Importantly,the supramolecular phosphorescent elastomer not only exhibits extending RTP emission with a lifetime up to 1.21 s,but also gives a visible afterglow of 20 s via encapsulation of BOH unities by the deep cavities of hydroxypropyl-β-cyclodextrin(β-CD-HP)and in situ polymerization.Especially,after doping organic dyes(Fluorescein isothiocyanate,Sulforhodamine 101,Rhodamine B),supramolecular phosphorescent elastomer achieves multicolor delayed fluorescence realized by RTP energy transfer from phosphorescent donor to dye acceptors,which possesses reversible photo-thermal responsiveness and maintains high efficiency in delayed emission even after dozens of cycles.Present research provides a new approach for constructing multicolor delayed fluorescent supramolecular elastomers.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.22379030,52001079,52261038)the Science and Technology Department of Guangxi Zhuang Autonomous(Nos.2024JJG160001,GuiKeAD21238022)the Innovation Project of Guangxi Graduate Education(No.YCBZ2023011)
文摘As a hydrogen storage material,both AlH_(3)and LiNH_(2)possess a high hydrogen capacity.However,the dehydrogenated AlH_(3)can hardly absorb hydrogen under normal conditions,while LiNH_(2)will generate NH_(3)rather than H_(2)upon decomposition.In this work,we report thatthe combination of AlH_(3)and LiNH_(2)through simple ball milling leads to partial reversibility of the AlH_(3)-LiNH_(2)system and the suppression of NH_(3)liberation.The negatively charged H^(δ-)in AlH_(3)will react with the positively charged H^(δ+)in LiNH_(2)through a redox reaction to form Li_(2)NH,AlN,and H_(2)at 120-170℃.After dehydrogenation at above 270℃,Li_(3)AlN_(2)is generated,which is crucial for the reversibility of this system.The more the Li3AlN2generated,the better the reversibility of this system.The dehydrogenation capacity of AlH_(3)+2LiNH_(2)at the third cycle(3.0 wt%)is higher than that of AlH_(3)+LiNH_(2)(1.2 wt%)due to the generation of more Li3AlN2.The role of AIH_(3)/Al in the AlH_(3)-LiNH_(2)system is to fix the nitrogen into the form of AIN and Li_(3)AlN_(2)and thus suppress the liberation of NH_(3).Therefore,the synergy of AlH_(3)and LiNH_(2)leads to the reversibility of the Li-Al-NH system and the suppression of NH_(3).
文摘BACKGROUND Posterior reversible encephalopathy syndrome(PRES)is a complex neurological disorder characterized by symptoms such as headaches,seizures,confusion,and visual disturbances.The pathophysiology of PRES involves endothelial dysfunction,disrupted cerebral autoregulation,and resulting vasogenic edema.Hypertension and other factors that alter cerebral autoregulation are critical in its development.Corticosteroids,widely used for their anti-inflammatory and immunosuppressive properties,play a controversial role in PRES.AIM To elucidate the dual role of corticosteroids in the context of PRES by critically evaluating the existing literature.Specifically,it seeks to assess the results of PRES induced by corticosteroid therapy and the efficacy and safety of corticosteroids in the treatment of PRES.By synthesizing case reports and series,this review aims to provide a comprehensive understanding of the mechanisms,clinical presentations,and management strategies associated with corticosteroid-related PRES.METHODS The review was carried out according to the PRISMA guidelines.The databases searched included Science Direct,PubMed,and Hinari.The search strategy encompassed terms related to corticosteroids and PRES.Studies were included if they were peer-reviewed articles examining corticosteroids in PRES,excluding non-English publications,reviews,and editorials.Data on patient demographics,clinical characteristics,imaging findings,corticosteroid regimens,and outcomes were extracted.The risk of bias was evaluated using the Joanna Briggs Institute tool for case reports.RESULTS A total of 56 cases of PRES(66.1%women,33.9%men)potentially induced by corticosteroids and 14 cases in which corticosteroids were used to treat PRES were identified.Cases of PRES reportedly caused by corticosteroids showed a mean age of approximately 25.2 years,with seizures,headaches,hypertension,and visual disturbances being common clinical sequelae.Magnetic resonance findings typically revealed vasogenic edema in the bilateral parieto-occipital lobes.High-dose or prolonged corticosteroid therapy was a significant risk factor.On the contrary,in the treatment cases,corticosteroids were associated with positive outcomes,including resolution of vasogenic edema and stabilization of symptoms,particularly in patients with underlying inflammatory or autoimmune diseases.CONCLUSION Corticosteroids have a dual role in PRES,capable of both inducing and treating the condition.The current body of literature suggests that corticosteroids may play a greater role as a precipitating agent of PRES rather than treating.Corticosteroids may induce PRES through hypertension and subsequent increased cerebral blood flow and loss of autoregulation.Corticosteroids may aid in the management of PRES:(1)Enhancing endothelial stability;(2)Antiinflammatory properties;and(3)Improving blood-brain barrier integrity.Mechanisms which may reduce or mitigate vasogenic edema formation.
基金supported by National Natural Science Foundation of China(Grant No.12171171)Natural Science Foundation of Fujian Province of China(Grant Nos.2022J01303 and 2023J01121)the Scientific Research Funds of Huaqiao University。
文摘In this paper,we investigate a class of reversible dynamical systems in four dimensions.The spectrums of their linear operators at the equilibria are assumed to have a pair of positive and negative real eigenvalues and a pair of purely imaginary eigenvalues for the small parameterμ>0,where these two real eigenvalues bifurcate from a double eigenvalue 0 forμ=0.It has been shown that this class of systems owns a generalized homoclinic solution with one hump at the center(a homoclinic solution exponentially approaching a periodic solution with a small amplitude).This paper gives a rigorous existence proof of two-hump solutions.These two humps are far away and are glued by the small oscillations in the middle if some appropriate free constants are activated.The obtained results are also applied to some classical systems.The ideas here may be used to study the existence of 2^(k)-hump solutions.
基金supported by the National Natural Science Foundation of China (No. 10671069)the ShanghaiLeading Academic Discipline Project (No. B407).
文摘The authors study the bifurcation of homoclinic orbits from a degenerate homoclinic orbit in reversible system. The unperturbed system is assumed to have saddle-center type equilibrium whose stable and unstable manifolds intersect in two-dimensional manifolds. A perturbation technique for the detection of symmetric and nonsymmetric homoctinic orbits near the primary homoclinic orbits is developed. Some known results are extended.
基金the National Natural Science Foundation of China (Nos. 10325103, 10531010)
文摘In this paper, a result on the persistence of lower dimensional invariant tori in Cd reversible systems is obtained under some conditions. The theorem is proved for any d which is larger than some constants.
文摘This paper is concerned with the boundedness of solutions for second order differential equations x + f(x, t)x + g(x, t) = 0, which are neither dissipative nor conservative, and where the functions f and g are odd in x and even in t, which are 1-periodic in t, and the function g satisfies g(x,t/x+, as|x| - +. Using the KAM theory for reversible systems, the author proves the existence of invariant tori and thus the boundedness of all the solutions and the existence of quasiperiodic solutions and subharmonic solutions.
基金supported by National Natural Science Foundation of China(Grant Nos.11701306,11671040 and 11601250)Higher Educational Science Program of Ningxia(Grant No.NGY201789)+1 种基金Construction of First-class Disciplines of Higher Education of Ningxia(pedagogy)(Grant No.NXYLXK2017B11)Key Program of Ningxia Normal University(Grant No.NXSFZD1708)。
文摘By using the Picard-Fuchs equation and the property of the Chebyshev space to the discontinuous differential system, we obtain an upper bound of the number of limit cycles for the nongeneric quadratic reversible system when it is perturbed inside all discontinuous polynomials with degree n.
基金Supported by NNSFC and NCET-04-0365in part by STCSM-06ZR14014
文摘For reversible systems of infinite dimension we prove an infinitely dimensional KAM theorem with an application to the network of weakly coupled oscillators of friction. The KAM theorem shows that there are many invariant tori of infinite dimension, and thus many almost periodic solutions, for the reversible systems.
基金The author is very grateful to Professors Ding Tongren and Liu Bin for their valuable suggestions for this paper.
文摘We are concerned with the boundedness of all the solutions for second order differential equation $$\ddot x + f\left( x \right)\dot x + g\left( x \right) = e\left( t \right),$$ , wheref(x) andg(x) are odd, e( t) is odd and 1-periodic, andg(x) satisfies $$Sign \left( x \right) \cdot g\left( x \right) \to + \infty ,\frac{{g\left( x \right)}}{x} \to 0,as\left| x \right| \to + \infty .$$
文摘Reversible system following Hamiltonian system turns out to be another type of equation which has aroused wide interest in recent years. One open problem is whether the celebrated KAM theory and Nekhoroshev method can be extended to reversible system. As showed in [5], there exist KAM tori in reversible system. In this paper, we give a preliminary discussion on whether there is Nekhoroshev type result in reversible system. In particular, we try to apply this method to the reducibility of a type of common reversible system.
基金Project(61074099)supported by the National Natural Science Foundation of ChinaProject(LJRC013)supported by Cultivation Program for Leading Talent of Innovation Team in Colleges and Universities of Hebei Province,ChinaProject(B705)supported by Doctor Foundation of Yanshan University,China
文摘To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control(CC) strategy based on invariance principle was proposed. Firstly, invariance principle was used to realize static decoupling between the speed and tension of reversible cold strip mill. Then, considering the influence caused by the time variation of steel coil radius and rotational inertia of the left and right coilers, as well as the uncertainties, a CC strategy that is composed of extended state observer(ESO) and global sliding mode control(GSMC) with backstepping adaptive was proposed,which further realized dynamic decoupling and coordination control for the speed and tension system. Theoretical analysis shows that the resulting closed-loop system is global bounded stable. Finally, the simulation was carried out on the speed and tension system of a 1422 mm reversible cold strip mill by using the actual data, and through the comparison of the other control strategies, validity of the proposed CC strategy was shown by the results.
文摘The rapid transmission of multimedia information has been achieved mainly by recent advancements in the Internet’s speed and information technology.In spite of this,advancements in technology have resulted in breaches of privacy and data security.When it comes to protecting private information in today’s Internet era,digital steganography is vital.Many academics are interested in digital video because it has a great capability for concealing important data.There have been a vast number of video steganography solutions developed lately to guard against the theft of confidential data.The visual imperceptibility,robustness,and embedding capacity of these approaches are all challenges that must be addressed.In this paper,a novel solution to reversible video steganography based on Discrete Wavelet Transform(DWT)and Quick Response(QR)codes is proposed to address these concerns.In order to increase the security level of the suggested method,an enhanced ElGamal cryptosystem has also been proposed.Prior to the embedding stage,the suggested method uses the modified ElGamal algorithm to encrypt secret QR codes.Concurrently,it applies two-dimensional DWT on the Y-component of each video frame resulting in Approximation(LL),Horizontal(LH),Vertical(HL),and Diagonal(HH)sub-bands.Then,the encrypted Low(L),Medium(M),Quantile(Q),and High(H)QR codes are embedded into the HL sub-band,HHsub-band,U-component,and V-component of video frames,respectively,using the Least Significant Bit(LSB)technique.As a consequence of extensive testing of the approach,it was shown to be very secure and highly invisible,as well as highly resistant to attacks from Salt&Pepper,Gaussian,Poisson,and Speckle noises,which has an average Structural Similarity Index(SSIM)of more than 0.91.Aside from visual imperceptibility,the suggested method exceeds current methods in terms of Peak Signal-to-Noise Ratio(PSNR)average of 52.143 dB,and embedding capacity 1 bpp.
文摘In this paper, using the KAM theorem of reversible systems, we obtain the boundednessof solutions, the existence of quasi-periodic solutions and subharmonic solutions for the non-linear differential equations of the second order which is neither conservative nor dissipative.
基金supported by National High Technology Research and Development Program of China(863 program)(No. 2009AA035002)the Fundamental Research Funds for the Central Universities(No.22A201514002)
文摘A new type of diacetylene monomer which includes a biphenylcarboxylic acid group as its head group is synthesized.Polymerization was performed after monomer form spherical vesicle by self-assembly in the water.The polydiacetylene displayed completely thermochromic color change in the range of 20-95℃ owing to the presence of strong π-π interaction caused by biphenyl group and hydrogen bonding between head group.
基金supported by Fundamental Research Funds for the Central Universities(2023KYJD1008)the Science Research Projects of the Anhui Higher Education Institutions of China(2022AH051582).
文摘Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.
基金support provided by the National Key R&D Program of China(No.2024YFE0101500)the National Natural Science Foundation of China(No.52272257)the Natural Science Foundation of Jiangsu Province(No.BK20240109).
文摘Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells(R-SOCs).Herein,we re-port an A-site high-entropy engineered perovskite oxide,La_(0.2)Pr_(0.2)Nd_(0.2)Ba_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF),and its electrocatalytic activity and stability property are systematically probed for tubular R-SOCs.The HE-LSCF air electrode exhibits excellent oxygen reduction reac-tion(ORR)activity with a low polarization resistance of 0.042Ω·cm^(2)at 700℃,which is much lower than that of La0.6Sr0.4Co_(0.8)Fe_(0.2)O_(3−δ)(LSCF),indicating the excellent catalytic activity of HE-LSCF.Meanwhile,the tubular R-SOCs with HE-LSCF shows a high peak power density of 1.18 W·cm^(−2)in the fuel cell mode and a promising electrolysis current density of−0.52 A·cm^(−2)at 1.5 V in the electrolysis mode with H_(2)(~10%H_(2)O)atmosphere at 700℃.More importantly,the tubular R-SOCs with HE-LSCF shows favorable stability under 180 h reversible cycling test.Our results show the high-entropy design can significantly enhance the activity and robustness of LSCF electrode for tubular R-SOCs.
基金financially supported by the Sichuan Science and Technology Program(2022YFS0025 and 2024YFFK0133)supported by the“Fundamental Research Funds for the Central Universities of China.”。
文摘Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots.Compared to active sensing devices,passive piezoelectric and triboelectric tactile sensors consume less power,but lack the capability to resolve static stimuli.Here,we address this issue by utilizing the unique polarization chemistry of conjugated polymers for the first time and propose a new type of bioinspired,passive,and bio-friendly tactile sensors for resolving both static and dynamic stimuli.Specifically,to emulate the polarization process of natural sensory cells,conjugated polymers(including poly(3,4-ethylenedioxythiophen e):poly(styrenesulfonate),polyaniline,or polypyrrole)are controllably polarized into two opposite states to create artificial potential differences.The controllable and reversible polarization process of the conjugated polymers is fully in situ characterized.Then,a micro-structured ionic electrolyte is employed to imitate the natural ion channels and to encode external touch stimulations into the variation in potential difference outputs.Compared with the currently existing tactile sensing devices,the developed tactile sensors feature distinct characteristics including fully organic composition,high sensitivity(up to 773 mV N^(−1)),ultralow power consumption(nW),as well as superior bio-friendliness.As demonstrations,both single point tactile perception(surface texture perception and material property perception)and two-dimensional tactile recognitions(shape or profile perception)with high accuracy are successfully realized using self-defined machine learning algorithms.This tactile sensing concept innovation based on the polarization chemistry of conjugated polymers opens up a new path to create robotic tactile sensors and prosthetic electronic skins.
文摘Electrochromic(EC)smart windows utilizing a reversible metal electrodeposition device(RMED)offer a compelling alternative for dynamically regulating transmissions of optical and thermal energy.An EC device(ECD)is constructed by reversible metal electrodeposition(RME)of Bi/Cu on WO_(3)·xH_(2)O film electrodeposited onto fluorine-doped tin oxide(FTO)transparent conductive glass.The electrolyte consists of CuCl_(2),BiCl_(3),KCl and HCl aqueous solution,supplying necessary components for both electrochemical and electrodeposition processes.The ECD shows ability to rapidly transition between colorless and black states,which achieves a large optical modulation of 77.0%at 570 nm.In the black state,the ECD exhibits a near-zero transmittance in the wavelength range of 400-1100 nm while maintaining 96.6%of its initial optical modulation after coloration/bleaching cycling of 60000 s,exhibiting good cyclic stability.This RMED has relatively high stability under open-circuit voltage and also possesses excellent heat insulation performance.The results offer a solution to overcome the poor cyclic stability of RMEDs and improve the optical modulation of ECDs.
基金funded by theNational Science and Technology Council of Taiwan under the grant number NSTC 113-2221-E-035-058.
文摘With the rapid expansion of multimedia data,protecting digital information has become increasingly critical.Reversible data hiding offers an effective solution by allowing sensitive information to be embedded in multimedia files while enabling full recovery of the original data after extraction.Audio,as a vital medium in communication,entertainment,and information sharing,demands the same level of security as images.However,embedding data in encrypted audio poses unique challenges due to the trade-offs between security,data integrity,and embedding capacity.This paper presents a novel interpolation-based reversible data hiding algorithm for encrypted audio that achieves scalable embedding capacity.By increasing sample density through interpolation,embedding opportunities are significantly enhanced while maintaining encryption throughout the process.The method further integrates multiple most significant bit(multi-MSB)prediction and Huffman coding to optimize compression and embedding efficiency.Experimental results on standard audio datasets demonstrate the proposed algorithm’s ability to embed up to 12.47 bits per sample with over 9.26 bits per sample available for pure embedding capacity,while preserving full reversibility.These results confirm the method’s suitability for secure applications that demand high embedding capacity and perfect reconstruction of original audio.This work advances reversible data hiding in encrypted audio by offering a secure,efficient,and fully reversible data hiding framework.
基金financially supported by the National Natural Science Foundation of China(No.22131008)。
文摘Purely organic room-temperature phosphorescence(RTP)is current hotspot in the research fields of chemistry,biology,materials etc.Herein,we report that photo-thermal double response reversible ultralong RTP flexible elastic material with multicolor delayed fluorescence,which is constructed by 4-biphenylboronic acid(BOH),polyethylene glycol,2,2-bis(hydroxymethyl)propionic acid,isophorone diamine and isophorone diisocyanate copolymer.Importantly,the supramolecular phosphorescent elastomer not only exhibits extending RTP emission with a lifetime up to 1.21 s,but also gives a visible afterglow of 20 s via encapsulation of BOH unities by the deep cavities of hydroxypropyl-β-cyclodextrin(β-CD-HP)and in situ polymerization.Especially,after doping organic dyes(Fluorescein isothiocyanate,Sulforhodamine 101,Rhodamine B),supramolecular phosphorescent elastomer achieves multicolor delayed fluorescence realized by RTP energy transfer from phosphorescent donor to dye acceptors,which possesses reversible photo-thermal responsiveness and maintains high efficiency in delayed emission even after dozens of cycles.Present research provides a new approach for constructing multicolor delayed fluorescent supramolecular elastomers.
