In this paper, the hybrid function projective synchronization (HFPS) of different chaotic systems with uncertain periodically time-varying parameters is carried out by Fourier series expansion and adaptive bounding te...In this paper, the hybrid function projective synchronization (HFPS) of different chaotic systems with uncertain periodically time-varying parameters is carried out by Fourier series expansion and adaptive bounding technique. Fourier series expansion is used to deal with uncertain periodically time-varying parameters. Adaptive bounding technique is used to compensate the bound of truncation errors. Using the Lyapunov stability theory, an adaptive control law and six parameter updating laws are constructed to make the states of two different chaotic systems asymptotically synchronized. The control strategy does not need to know the parameters thoroughly if the time-varying parameters are periodical functions. Finally, in order to verify the effectiveness of the proposed scheme, the HFPS between Lorenz system and Chen system is completed successfully by using this scheme.展开更多
The adaptively compressed exchange(ACE)operator is a low-rank representation of the Fock exchange,avoiding any loss of precision.We present an application of this method in the formalism of linearized augmented plane ...The adaptively compressed exchange(ACE)operator is a low-rank representation of the Fock exchange,avoiding any loss of precision.We present an application of this method in the formalism of linearized augmented plane waves(LAPW)to hybrid functionals with range separation.For this purpose,we extend the functionality of the LAPW-specific Poisson solver employing the pseudocharge method for the short-and long-range interaction kernels.To make these calculations more affordable,we revise the most expensive steps in the pseudocharge method and reduce their computational complexity.As a result,this implementation is a first step towards cubic-scaling hybrid calculations employing LAPW with respect to the number of atoms.We apply our code for assessing the numerical quality of band gaps computed with hybrid functionals in the literature,employing a test set consisting of 26 materials.展开更多
The electronic properties of zinc-blende BxGal-xN alloys are comparatively investigated by employ- ing both the Perdewe-Burkee-Ernzerhof generalized-gradient approximation （PBE-GGA） and the Heyd-Scuseria- Ernzerhof ...The electronic properties of zinc-blende BxGal-xN alloys are comparatively investigated by employ- ing both the Perdewe-Burkee-Ernzerhof generalized-gradient approximation （PBE-GGA） and the Heyd-Scuseria- Ernzerhof screened hybrid functional methods （HSE06）. HSE06 reproduced much closer ground-state properties to experiments. Large and composition-dependent bowing parameters br for the direct band gaps were obtained from both PBE and HSE06. The crossover composition where alloy switches from direct to indirect was predicted to occur at very similar x from PBE and HSE06. We can obtain direct gap BxGal-xN with a gap value much larger than that of GaN by alloying x 〈 0.557 boron into GaN.展开更多
Hybrid density functional theory is employed to systematically investigate the structural,magnetic,vibrational,thermodynamic properties of plutonium monocarbide（Pu C and Pu C0.75）.For comparison,the results obtained...Hybrid density functional theory is employed to systematically investigate the structural,magnetic,vibrational,thermodynamic properties of plutonium monocarbide（Pu C and Pu C0.75）.For comparison,the results obtained by DFT,DFT ＋ U are also given.For Pu C and Pu C0.75,Fock-0.25 hybrid functional gives the best lattice constants and predicts the correct ground states of antiferromagnetic（AFM） structure.The calculated phonon spectra suggest that Pu C and Pu C0.75 are dynamically stable.Values of the Helmholtz free energy ？F,internal energy ？E,entropy S,and constant-volume specific heat Cv of Pu C and Pu C0.75 are given.The results are in good agreement with available experimental or theoretical data.As for the chemical bonding nature,the difference charge densities,the partial densities of states and the Bader charge analysis suggest that the Pu–C bonds of Pu C and Pu C0.75 have a mixture of covalent character and ionic character.The effect of carbon vacancy on the chemical bonding is also discussed in detail.We expect that our study can provide some useful reference for further experimental research on the phonon density of states,thermodynamic properties of the plutonium monocarbide.展开更多
The electronic properties and stability of Li-doped ZnO with various defects have been stud- ied by calculating the electronic structures and defect formation energies via first-principles calculations using hybrid Ha...The electronic properties and stability of Li-doped ZnO with various defects have been stud- ied by calculating the electronic structures and defect formation energies via first-principles calculations using hybrid Hartree-Fock and density functional methods. The results from formation energy calculations show that Li pair complexes have the lowest formation energy in most circumstances and they consume most of the Li content in Li doped ZnO, which make the p-type conductance hard to obtain. The formation of Li pair complexes is the main obstacle to realize p-type conductance in Li doped ZnO. However, the formation energy of Lizn decreases as environment changes from Zn-rich to O-rich and becomes more stable than that of Li-pair complexes at highly O-rich environment. Therefore, p-type conductance can be obtained by Li doped ZnO grown or post annealed in oxygen rich atmosphere.展开更多
This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a f...This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, a hybrid graded element is formulated based on the obtained fundamental solution and a frame field. As a result, the graded properties of FGMs are naturally reflected by using the fundamental solution to interpolate the intra-element field. Further, Stefest＇s algorithm is employed to convert the results in Laplace space back into the time-space domain. Finally, the performance of the proposed method is assessed by several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.展开更多
A new type of hybrid finite element formulation with fundamental solutions as internal interpolation functions, named as HFS-FEM, is presented in this paper and used for solving two dimensional heat conduction problem...A new type of hybrid finite element formulation with fundamental solutions as internal interpolation functions, named as HFS-FEM, is presented in this paper and used for solving two dimensional heat conduction problems in single and multi-layer materials. In the proposed approach, a new variational functional is firstly constructed for the proposed HFS-FE model and the related existence of extremum is presented. Then, the assumed internal potential field constructed by the linear combination of fundamental solutions at points outside the elemental domain under consideration is used as the internal interpolation function, which analytically satisfies the governing equation within each element. As a result, the domain integrals in the variational functional formulation can be converted into the boundary integrals which can significantly simplify the calculation of the element stiffness matrix. The independent frame field is also introduced to guarantee the inter-element continuity and the stationary condition of the new variational functional is used to obtain the final stiffness equations. The proposed method inherits the advantages of the hybrid Trefftz finite element method （HT-FEM） over the conventional finite element method （FEM） and boundary element method （BEM）, and avoids the difficulty in selecting appropriate terms of T-complete functions used in HT-FEM, as the fundamental solutions contain usually one term only, rather than a series containing infinitely many terms. Further, the fundamental solutions of a problem are, in general, easier to derive than the T-complete functions of that problem. Finally, several examples are presented to assess the performance of the proposed method, and the obtained numerical results show good numerical accuracy and remarkable insensitivity to mesh distortion.展开更多
An unidirectional and bidirectional hybrid connective star network model with coupling time-delay is constructed in this paper. According to synchronization error systems, adaptive controllers for each node are struct...An unidirectional and bidirectional hybrid connective star network model with coupling time-delay is constructed in this paper. According to synchronization error systems, adaptive controllers for each node are structured by using the linear system stability method and the Lyapunov stability method. These adaptive controllers can realize the modified functional projective synchronization between each node of star network and an isolated node by argument and analysis. Finally, the corrective and effective of the adaptive controllers are illustrated by some numerical examples.展开更多
Fibers are low-cost substrates that are abundantly used in our daily lives. This review highlights recent advances in the fabrication and application of multifunctional fibers to achieve fibers with unique functions f...Fibers are low-cost substrates that are abundantly used in our daily lives. This review highlights recent advances in the fabrication and application of multifunctional fibers to achieve fibers with unique functions for specific applications ranging from textile electronics to biomedical applications. By incorporating various nanomaterials such as carbon nanomaterials, metallic nanomaterials, and hydrogel-based biomaterials, the functions of fibers can be precisely engineered. This review also highlights the performance of the functional fibers and electronic materials incorporated with textiles and demonstrates their practical application in pressure/tensile sensors,chemical/biosensors, and drug delivery. Textile technologies in which fibers containing biological factors and cells are formed and assembled into constructions with biomimetic properties have attracted substantial attention in the field of tissue engineering. We also discuss the current limitations of functional textile-based devices and their prospects for use in various future applications.展开更多
Ladder-like polysilsesquioxanes （LPSQs） with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst. The concentration and activity of amino groups were investigated by Fourier ...Ladder-like polysilsesquioxanes （LPSQs） with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst. The concentration and activity of amino groups were investigated by Fourier transform infrared spectroscopy. Polyimide （PI）/LPSQ hybrid films have been prepared by incorporating of the obtained LPSQs with different amino contents into PI matrix, respectively. The interfacial interactions between PI matrix and LPSQ were studied with scanning electron microscopy and X-ray photoelectron spectroscopy, meanwhile the thermal and mechanical properties of the hybrid films were studied using dynamic mechanical analysis and tensile tests. The results indicate that the functionality of LPSQ has great effects on the interfacial interactions and the properties of hybrid films. With the increase of amino content, both the interracial interactions and the cross-linking density of hybrids enhanced, which results in the decline of surface silicon concentration, increase of Young＇s modulus and drop of elongation at break. Excessive amino content makes the hybrid films brittle and leads to incomplete imidization.展开更多
Functionalized silica hybrid materials are extensively studied and applied materials in the field of science and technology. Functionalization is an approach, which allows for the application of organic components in ...Functionalized silica hybrid materials are extensively studied and applied materials in the field of science and technology. Functionalization is an approach, which allows for the application of organic components in the improvement of the design, properties and potential application of silicate materials. Silica hybrid materials, functionalized via incorporation of organic components (chitosan and methacrylic acid) were synthesized by the sol-gel method. The base silica structure of the hybrids was obtained via hydrolysis and condensation of the silicate precursor, tetraethyl orthosilicate. The investigations of synthesized hybrids are focused on the influence of the nature and quantity of functional organic components on their final structures and properties. The structural characteristics of obtained hybrid materials were investigated using XRD, FTIR, SEM and DTA/TG analysis. The obtained results presented the formation of amorphous porous structure and the organic components are evenly distributed into the silica network. The functional radicals of chitosan and methacrylic acid (amine, hydroxyl groups) exist in the hybrid structure as free reactive centers, as their quantity increases with increasing the organic amount. The swelling behavior in acidic and neutral solutions of the synthesized materials is investigated and the results presented, that the silicate materials exhibit hydrophilic character.展开更多
By the aid of the penalty function method, the equilibrium restriction conditions were introduced to the isoparametric hybrid finite element analysis, and the concrete application course of the penalty function method...By the aid of the penalty function method, the equilibrium restriction conditions were introduced to the isoparametric hybrid finite element analysis, and the concrete application course of the penalty function method in three-dimensional isoparametdc hybrid finite element was discussed. The separated penalty parameters method and the optimal hybrid element model with penalty balance were also presented. The penalty balance method can effectively refrain the parasitical stress on the premise of no additional degrees of freedom. The numeric experiment shows that the presented element not only is effective in improving greatly the numeric calculation precision of distorted grids but also has the universality.展开更多
The most commonly used and studied hybrid halide perovskite is ABX_3, where A usually stands for CH_3NH_3, B for Pb, and X for I. A lead-free perovskite with high stability and ideal electronic band structure would be...The most commonly used and studied hybrid halide perovskite is ABX_3, where A usually stands for CH_3NH_3, B for Pb, and X for I. A lead-free perovskite with high stability and ideal electronic band structure would be of essence, especially considering the toxicity of lead. In this work, we have considered 11 metal elements for the B site and three halide elements(Cl, Br, and I) including various combinations among the three halides for the X site. A total number of 99 hybrid perovskites are studied to understand how the crystal structure, band gap and stability can be tuned by the chemistry modification, i.e., the replacement of toxic element, Pb in the original MAPbX_3, with non-toxic metal elements. We find that the favorable substitutes for Pb in MAPbI_3 are Ge and Sn.展开更多
基金supported by National Natural Science Foundation of China (No.60974139)Fundamental Research Funds for the Central Universities (No.72103676)
文摘In this paper, the hybrid function projective synchronization (HFPS) of different chaotic systems with uncertain periodically time-varying parameters is carried out by Fourier series expansion and adaptive bounding technique. Fourier series expansion is used to deal with uncertain periodically time-varying parameters. Adaptive bounding technique is used to compensate the bound of truncation errors. Using the Lyapunov stability theory, an adaptive control law and six parameter updating laws are constructed to make the states of two different chaotic systems asymptotically synchronized. The control strategy does not need to know the parameters thoroughly if the time-varying parameters are periodical functions. Finally, in order to verify the effectiveness of the proposed scheme, the HFPS between Lorenz system and Chen system is completed successfully by using this scheme.
基金supported by the European Union's Horizon 2020 research and innovation program under the grant agreement No.951786(NOMAD CoE)the Latvian Quantum Initiative within European Union Recovery and Resilience Facility project No.2.3.1.1.i.0/1/22/I/CFLA/001.We also acknowledge the EuroHPC Joint Undertaking for awarding access to the EuroHPC supercomputer LUMI,hosted by CSC(Finland)and the LUMI consortium through a EuroHPC Development Access call.
文摘The adaptively compressed exchange(ACE)operator is a low-rank representation of the Fock exchange,avoiding any loss of precision.We present an application of this method in the formalism of linearized augmented plane waves(LAPW)to hybrid functionals with range separation.For this purpose,we extend the functionality of the LAPW-specific Poisson solver employing the pseudocharge method for the short-and long-range interaction kernels.To make these calculations more affordable,we revise the most expensive steps in the pseudocharge method and reduce their computational complexity.As a result,this implementation is a first step towards cubic-scaling hybrid calculations employing LAPW with respect to the number of atoms.We apply our code for assessing the numerical quality of band gaps computed with hybrid functionals in the literature,employing a test set consisting of 26 materials.
基金supported by the Fundamental Research Funds for the Central Universities(No.2010LKWL03)the Special Fund for Theoretical Physics(No.11047130)the National Natural Science Foundation of China(No.11104345)
文摘The electronic properties of zinc-blende BxGal-xN alloys are comparatively investigated by employ- ing both the Perdewe-Burkee-Ernzerhof generalized-gradient approximation （PBE-GGA） and the Heyd-Scuseria- Ernzerhof screened hybrid functional methods （HSE06）. HSE06 reproduced much closer ground-state properties to experiments. Large and composition-dependent bowing parameters br for the direct band gaps were obtained from both PBE and HSE06. The crossover composition where alloy switches from direct to indirect was predicted to occur at very similar x from PBE and HSE06. We can obtain direct gap BxGal-xN with a gap value much larger than that of GaN by alloying x 〈 0.557 boron into GaN.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21371160 and 21401173)
文摘Hybrid density functional theory is employed to systematically investigate the structural,magnetic,vibrational,thermodynamic properties of plutonium monocarbide（Pu C and Pu C0.75）.For comparison,the results obtained by DFT,DFT ＋ U are also given.For Pu C and Pu C0.75,Fock-0.25 hybrid functional gives the best lattice constants and predicts the correct ground states of antiferromagnetic（AFM） structure.The calculated phonon spectra suggest that Pu C and Pu C0.75 are dynamically stable.Values of the Helmholtz free energy ？F,internal energy ？E,entropy S,and constant-volume specific heat Cv of Pu C and Pu C0.75 are given.The results are in good agreement with available experimental or theoretical data.As for the chemical bonding nature,the difference charge densities,the partial densities of states and the Bader charge analysis suggest that the Pu–C bonds of Pu C and Pu C0.75 have a mixture of covalent character and ionic character.The effect of carbon vacancy on the chemical bonding is also discussed in detail.We expect that our study can provide some useful reference for further experimental research on the phonon density of states,thermodynamic properties of the plutonium monocarbide.
文摘The electronic properties and stability of Li-doped ZnO with various defects have been stud- ied by calculating the electronic structures and defect formation energies via first-principles calculations using hybrid Hartree-Fock and density functional methods. The results from formation energy calculations show that Li pair complexes have the lowest formation energy in most circumstances and they consume most of the Li content in Li doped ZnO, which make the p-type conductance hard to obtain. The formation of Li pair complexes is the main obstacle to realize p-type conductance in Li doped ZnO. However, the formation energy of Lizn decreases as environment changes from Zn-rich to O-rich and becomes more stable than that of Li-pair complexes at highly O-rich environment. Therefore, p-type conductance can be obtained by Li doped ZnO grown or post annealed in oxygen rich atmosphere.
文摘This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, a hybrid graded element is formulated based on the obtained fundamental solution and a frame field. As a result, the graded properties of FGMs are naturally reflected by using the fundamental solution to interpolate the intra-element field. Further, Stefest＇s algorithm is employed to convert the results in Laplace space back into the time-space domain. Finally, the performance of the proposed method is assessed by several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.
文摘A new type of hybrid finite element formulation with fundamental solutions as internal interpolation functions, named as HFS-FEM, is presented in this paper and used for solving two dimensional heat conduction problems in single and multi-layer materials. In the proposed approach, a new variational functional is firstly constructed for the proposed HFS-FE model and the related existence of extremum is presented. Then, the assumed internal potential field constructed by the linear combination of fundamental solutions at points outside the elemental domain under consideration is used as the internal interpolation function, which analytically satisfies the governing equation within each element. As a result, the domain integrals in the variational functional formulation can be converted into the boundary integrals which can significantly simplify the calculation of the element stiffness matrix. The independent frame field is also introduced to guarantee the inter-element continuity and the stationary condition of the new variational functional is used to obtain the final stiffness equations. The proposed method inherits the advantages of the hybrid Trefftz finite element method （HT-FEM） over the conventional finite element method （FEM） and boundary element method （BEM）, and avoids the difficulty in selecting appropriate terms of T-complete functions used in HT-FEM, as the fundamental solutions contain usually one term only, rather than a series containing infinitely many terms. Further, the fundamental solutions of a problem are, in general, easier to derive than the T-complete functions of that problem. Finally, several examples are presented to assess the performance of the proposed method, and the obtained numerical results show good numerical accuracy and remarkable insensitivity to mesh distortion.
基金Supported by the National Natural Science Foundation of China(11161027)Natural Science Foundation of Gansu Province(1610RJZA080)the Foundation of Gansu Education Bureau(2017A-155)
文摘An unidirectional and bidirectional hybrid connective star network model with coupling time-delay is constructed in this paper. According to synchronization error systems, adaptive controllers for each node are structured by using the linear system stability method and the Lyapunov stability method. These adaptive controllers can realize the modified functional projective synchronization between each node of star network and an isolated node by argument and analysis. Finally, the corrective and effective of the adaptive controllers are illustrated by some numerical examples.
基金supported by the Priority Research Centers Program(No.2012-0006689)through the National Research Foundation(NRF)of Korea funded by the Ministry of Education,Science and Technology(MEST)the R&D program of MOTIE/KEIT[10064081,Devclopment of fiber-based flexible multimodal pressure sensor and algorithm for gesture/posture-recognizable wearable devices]+3 种基金partial support from the National Research Foundation of Korea(No.NRF-2017K2A9A2A06013377,NRF-2017M3A7B4049466)the Yonsei University Future-leading Research Initiative and Implantable artificial electronic skin for an ubiquitous healthcare system of 2016-12-0050supported by KIST Project(Nos.2E26900,2E27630)supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2016R1A6A3A03006491)
文摘Fibers are low-cost substrates that are abundantly used in our daily lives. This review highlights recent advances in the fabrication and application of multifunctional fibers to achieve fibers with unique functions for specific applications ranging from textile electronics to biomedical applications. By incorporating various nanomaterials such as carbon nanomaterials, metallic nanomaterials, and hydrogel-based biomaterials, the functions of fibers can be precisely engineered. This review also highlights the performance of the functional fibers and electronic materials incorporated with textiles and demonstrates their practical application in pressure/tensile sensors,chemical/biosensors, and drug delivery. Textile technologies in which fibers containing biological factors and cells are formed and assembled into constructions with biomimetic properties have attracted substantial attention in the field of tissue engineering. We also discuss the current limitations of functional textile-based devices and their prospects for use in various future applications.
基金financially supported by the National Natural Science Foundation of China (No.51073020)
文摘Ladder-like polysilsesquioxanes （LPSQs） with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst. The concentration and activity of amino groups were investigated by Fourier transform infrared spectroscopy. Polyimide （PI）/LPSQ hybrid films have been prepared by incorporating of the obtained LPSQs with different amino contents into PI matrix, respectively. The interfacial interactions between PI matrix and LPSQ were studied with scanning electron microscopy and X-ray photoelectron spectroscopy, meanwhile the thermal and mechanical properties of the hybrid films were studied using dynamic mechanical analysis and tensile tests. The results indicate that the functionality of LPSQ has great effects on the interfacial interactions and the properties of hybrid films. With the increase of amino content, both the interracial interactions and the cross-linking density of hybrids enhanced, which results in the decline of surface silicon concentration, increase of Young＇s modulus and drop of elongation at break. Excessive amino content makes the hybrid films brittle and leads to incomplete imidization.
文摘Functionalized silica hybrid materials are extensively studied and applied materials in the field of science and technology. Functionalization is an approach, which allows for the application of organic components in the improvement of the design, properties and potential application of silicate materials. Silica hybrid materials, functionalized via incorporation of organic components (chitosan and methacrylic acid) were synthesized by the sol-gel method. The base silica structure of the hybrids was obtained via hydrolysis and condensation of the silicate precursor, tetraethyl orthosilicate. The investigations of synthesized hybrids are focused on the influence of the nature and quantity of functional organic components on their final structures and properties. The structural characteristics of obtained hybrid materials were investigated using XRD, FTIR, SEM and DTA/TG analysis. The obtained results presented the formation of amorphous porous structure and the organic components are evenly distributed into the silica network. The functional radicals of chitosan and methacrylic acid (amine, hydroxyl groups) exist in the hybrid structure as free reactive centers, as their quantity increases with increasing the organic amount. The swelling behavior in acidic and neutral solutions of the synthesized materials is investigated and the results presented, that the silicate materials exhibit hydrophilic character.
文摘By the aid of the penalty function method, the equilibrium restriction conditions were introduced to the isoparametric hybrid finite element analysis, and the concrete application course of the penalty function method in three-dimensional isoparametdc hybrid finite element was discussed. The separated penalty parameters method and the optimal hybrid element model with penalty balance were also presented. The penalty balance method can effectively refrain the parasitical stress on the premise of no additional degrees of freedom. The numeric experiment shows that the presented element not only is effective in improving greatly the numeric calculation precision of distorted grids but also has the universality.
基金the Shanghai Sailing(YANG FAN)Program(No.16YF1406000)the Startup Fund from Shanghai Jiao Tong University
文摘The most commonly used and studied hybrid halide perovskite is ABX_3, where A usually stands for CH_3NH_3, B for Pb, and X for I. A lead-free perovskite with high stability and ideal electronic band structure would be of essence, especially considering the toxicity of lead. In this work, we have considered 11 metal elements for the B site and three halide elements(Cl, Br, and I) including various combinations among the three halides for the X site. A total number of 99 hybrid perovskites are studied to understand how the crystal structure, band gap and stability can be tuned by the chemistry modification, i.e., the replacement of toxic element, Pb in the original MAPbX_3, with non-toxic metal elements. We find that the favorable substitutes for Pb in MAPbI_3 are Ge and Sn.
