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
Lysine-targeting reversible covalent inhibitors,particularly salicylaldehyde-based compounds such as the Food and Drug Administration(FDA)-approved drug Voxelotor,exhibit significant therapeutic potential but are limi...Lysine-targeting reversible covalent inhibitors,particularly salicylaldehyde-based compounds such as the Food and Drug Administration(FDA)-approved drug Voxelotor,exhibit significant therapeutic potential but are limited by challenges including instability and off-target effects.To overcome these limitations in kinase inhibitor A5,we devised a pH-responsive prodrug strategy by masking its reactive aldehyde group with an acid-labile hydrazone linkage and enhancing intracellular delivery through conjugation with FK506.The optimized prodrug demonstrated robust antitumor efficacy in K562 tumor-bearing mice.Furthermore,the incorporation of the photosensitizer chlorin e6(Ce6)led to the formation of self-assembled nanoparticles(AKNP),which not only improved physiological stability and prolonged tumor retention but also enabled light-triggered release of A5 in conjunction with photodynamic therapy(PDT).Our study thus presents a promising prodrug self-assembly strategy that combines the on-demand release of a novel lysine-targeting,reversible covalent kinase inhibitor with PDT in clinical cancer therapy.展开更多
Reversible data hiding(RDH)enables secret data embedding while preserving complete cover image recovery,making it crucial for applications requiring image integrity.The pixel value ordering(PVO)technique used in multi...Reversible data hiding(RDH)enables secret data embedding while preserving complete cover image recovery,making it crucial for applications requiring image integrity.The pixel value ordering(PVO)technique used in multi-stego images provides good image quality but often results in low embedding capability.To address these challenges,this paper proposes a high-capacity RDH scheme based on PVO that generates three stego images from a single cover image.The cover image is partitioned into non-overlapping blocks with pixels sorted in ascending order.Four secret bits are embedded into each block’s maximum pixel value,while three additional bits are embedded into the second-largest value when the pixel difference exceeds a predefined threshold.A similar embedding strategy is also applied to the minimum side of the block,including the second-smallest pixel value.This design enables each block to embed up to 14 bits of secret data.Experimental results demonstrate that the proposed method achieves significantly higher embedding capacity and improved visual quality compared to existing triple-stego RDH approaches,advancing the field of reversible steganography.展开更多
Thermally activated delayed fluorescence(TADF)exciplexes,constituted of donor-acceptor moieties,have garnered mounting interest because of their promising potential to obtain high-performance electroluminescent device...Thermally activated delayed fluorescence(TADF)exciplexes,constituted of donor-acceptor moieties,have garnered mounting interest because of their promising potential to obtain high-performance electroluminescent devices.However,the moderate reverse intersystem crossing(RISC)of current reported exciplex systems and the lack of clear molecular design concepts to improve this situation have distinctly hindered the further use of exciplexes in organic light-emitting diodes(OLEDs).Herein,we conduct an exploration of exciplex systems founded upon[2,2]paracyclophane(PCP)-containing donor molecules and a triazine acceptor,which exhibit very fast RISC processes with a rate constant(k_(RISC))up to 8.3×10^(6) s^(-1)benefiting from the efficient interactions between the donor and acceptor fragments induced by the peripheral spatial-blocking of PCP group.Utilizing these deep-blue exciplexes as hosts and a multiple resonance(MR)molecule as emitter,pure-blue narrowband OLEDs with CIE coordinates of(0.124,0.137),a full-width at half-maximum(FWHM)of 23 nm,and a high external quantum efficiency(EQE)of around 30%are accessed.This study paves the way for developing blue OLEDs using PCP-based exciplex materials with an enhanced RISC process.展开更多
To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hyb...To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hybrid modular multilevel converter–capacitor-commutated line-commutated converter(MMC-CLCC)HVDC transmission system and its corresponding control strategy.First,the system topology is constructed,and a submodule configuration method for the MMC—combining full-bridge submodules(FBSMs)and half-bridge submodules(HBSMs)—is proposed to enable direct power flow reversal.Second,a hierarchical control strategy is introduced,includingMMCvoltage control,CLCC current control,and a coordinationmechanism,along with the derivation of the hybrid system’s power flow reversal characteristics.Third,leveraging the CLCC’s fast current regulation and theMMC’s negative voltage control capability,a coordinated power flow reversal control strategy is developed.Finally,an 800 kV MMC-CLCC hybrid HVDC system is modeled in PSCAD/EMTDC to validate the power flow reversal performance under a high proportion of full-bridge submodule configuration.Results demonstrate that the proposed control strategy enables rapid(1-s transition)and smooth switching of bidirectional power flow without modifying the structure of primary equipment:the transient fluctuation ofDC voltage from the rated value(UdcN)to themaximumreverse voltage(-kUdcN)is less than 5%;the DC current strictly follows the preset characteristic curve with a deviation of≤3%;the active power reverses continuously,and the system maintains stable operation throughout the reversal process.展开更多
We deal with the stability of zero solutions of planar Hamiltonian and reversible systems which are quasi-periodic in the time variable.Under some reasonable assumptionswe prove the existence of quasi-periodic solutio...We deal with the stability of zero solutions of planar Hamiltonian and reversible systems which are quasi-periodic in the time variable.Under some reasonable assumptionswe prove the existence of quasi-periodic solutions in a small neighborhood of zero solutions and the stability of zero 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
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 grants from National Key R&D Program of China(No.2022YFA1104800)Shenzhen Science and Technology Program(No.JCYJ20210324124214038)+4 种基金National Natural Science Foundation of China(Nos.52072418,82300016)Natural Science Foundation of Guangdong Province(No.2023A1515140072)Shenzhen Key Laboratory of Neural Cell Reprogramming and Drug Research,Social Development Science and Technology Key Project of Dongguan(No.20231800940512)the National Medical Research Council(NMRC,No.23-0740-A0001)the Ministry of Education(MOE,No.T2EP10222-0002)of Singapore.
文摘Lysine-targeting reversible covalent inhibitors,particularly salicylaldehyde-based compounds such as the Food and Drug Administration(FDA)-approved drug Voxelotor,exhibit significant therapeutic potential but are limited by challenges including instability and off-target effects.To overcome these limitations in kinase inhibitor A5,we devised a pH-responsive prodrug strategy by masking its reactive aldehyde group with an acid-labile hydrazone linkage and enhancing intracellular delivery through conjugation with FK506.The optimized prodrug demonstrated robust antitumor efficacy in K562 tumor-bearing mice.Furthermore,the incorporation of the photosensitizer chlorin e6(Ce6)led to the formation of self-assembled nanoparticles(AKNP),which not only improved physiological stability and prolonged tumor retention but also enabled light-triggered release of A5 in conjunction with photodynamic therapy(PDT).Our study thus presents a promising prodrug self-assembly strategy that combines the on-demand release of a novel lysine-targeting,reversible covalent kinase inhibitor with PDT in clinical cancer therapy.
基金funded by University of Transport and Communications(UTC)under grant number T2025-CN-004.
文摘Reversible data hiding(RDH)enables secret data embedding while preserving complete cover image recovery,making it crucial for applications requiring image integrity.The pixel value ordering(PVO)technique used in multi-stego images provides good image quality but often results in low embedding capability.To address these challenges,this paper proposes a high-capacity RDH scheme based on PVO that generates three stego images from a single cover image.The cover image is partitioned into non-overlapping blocks with pixels sorted in ascending order.Four secret bits are embedded into each block’s maximum pixel value,while three additional bits are embedded into the second-largest value when the pixel difference exceeds a predefined threshold.A similar embedding strategy is also applied to the minimum side of the block,including the second-smallest pixel value.This design enables each block to embed up to 14 bits of secret data.Experimental results demonstrate that the proposed method achieves significantly higher embedding capacity and improved visual quality compared to existing triple-stego RDH approaches,advancing the field of reversible steganography.
基金supported by the National Key R&D Program of China(2022YFE0109000)the National Natural Science Foundation of China(21975152,92256304,U23A20593)+1 种基金the China Postdoctoral Science Foundation(2022M722028)the Deutsche Forschungsgemeinschaft(DFG)under Germany’s Excellence Strategy(3DMM2O-EXC-2082/1-390761711)。
文摘Thermally activated delayed fluorescence(TADF)exciplexes,constituted of donor-acceptor moieties,have garnered mounting interest because of their promising potential to obtain high-performance electroluminescent devices.However,the moderate reverse intersystem crossing(RISC)of current reported exciplex systems and the lack of clear molecular design concepts to improve this situation have distinctly hindered the further use of exciplexes in organic light-emitting diodes(OLEDs).Herein,we conduct an exploration of exciplex systems founded upon[2,2]paracyclophane(PCP)-containing donor molecules and a triazine acceptor,which exhibit very fast RISC processes with a rate constant(k_(RISC))up to 8.3×10^(6) s^(-1)benefiting from the efficient interactions between the donor and acceptor fragments induced by the peripheral spatial-blocking of PCP group.Utilizing these deep-blue exciplexes as hosts and a multiple resonance(MR)molecule as emitter,pure-blue narrowband OLEDs with CIE coordinates of(0.124,0.137),a full-width at half-maximum(FWHM)of 23 nm,and a high external quantum efficiency(EQE)of around 30%are accessed.This study paves the way for developing blue OLEDs using PCP-based exciplex materials with an enhanced RISC process.
基金supported by Science and Technology Project of the headquarters of the State Grid Corporation of China(No.5500-202324492A-3-2-ZN).
文摘To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hybrid modular multilevel converter–capacitor-commutated line-commutated converter(MMC-CLCC)HVDC transmission system and its corresponding control strategy.First,the system topology is constructed,and a submodule configuration method for the MMC—combining full-bridge submodules(FBSMs)and half-bridge submodules(HBSMs)—is proposed to enable direct power flow reversal.Second,a hierarchical control strategy is introduced,includingMMCvoltage control,CLCC current control,and a coordinationmechanism,along with the derivation of the hybrid system’s power flow reversal characteristics.Third,leveraging the CLCC’s fast current regulation and theMMC’s negative voltage control capability,a coordinated power flow reversal control strategy is developed.Finally,an 800 kV MMC-CLCC hybrid HVDC system is modeled in PSCAD/EMTDC to validate the power flow reversal performance under a high proportion of full-bridge submodule configuration.Results demonstrate that the proposed control strategy enables rapid(1-s transition)and smooth switching of bidirectional power flow without modifying the structure of primary equipment:the transient fluctuation ofDC voltage from the rated value(UdcN)to themaximumreverse voltage(-kUdcN)is less than 5%;the DC current strictly follows the preset characteristic curve with a deviation of≤3%;the active power reverses continuously,and the system maintains stable operation throughout the reversal process.
基金supported by National Natural Science Foundation of China(Grant No.10325103)Doctoral Fund of Ministry of Education of China(Grant No.20070001041)
文摘We deal with the stability of zero solutions of planar Hamiltonian and reversible systems which are quasi-periodic in the time variable.Under some reasonable assumptionswe prove the existence of quasi-periodic solutions in a small neighborhood of zero solutions and the stability of zero 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.
