Objective:To observe the clinical efficacy of the method of softening the liver,harmonizing the spleen,and unblocking the orifices in the treatment of Xiaoke Neizhang with Qi and Yin deficiency type.Methods:Seventy-tw...Objective:To observe the clinical efficacy of the method of softening the liver,harmonizing the spleen,and unblocking the orifices in the treatment of Xiaoke Neizhang with Qi and Yin deficiency type.Methods:Seventy-two patients with Xiaoke Neizhang of qi and yin deficiency type were selected from March 2024 to May 2025 and divided into a treatment group and a control group with 36 cases each according to the random number table method.The treatment group was treated with the method of softening the liver,harmonizing the spleen,and unblocking the orifices,which included oral administration of Softening the Liver and Harmonizing the Spleen Pills combined with iontophoresis of Xuesaitong Injection.The control group was treated with oral administration of calcium dobesilate capsules.Both groups were treated for 2 courses,and multiple indicators such as visual acuity,fundus condition,and TCM syndrome scores were compared between the two groups.Results:The total effective rate of the treatment group was higher than that of the control group.There were significant differences in visual acuity,fundus condition,and TCM syndrome scores between and within the groups(P<0.05).Conclusion:The method of softening the liver,harmonizing the spleen,and unblocking the orifices has a definite clinical effect in the treatment of Xiaoke Neizhang with Qi and Yin deficiency type.It has a direct effect,is painless,easy for patients to accept,and has high clinical application value.展开更多
Geologic time is an essential dimension in geological research,acting as a pivotal attribute that integrates data across various subdisciplines.The Geologic Time Scale(GTS)provides a formal framework for interpreting ...Geologic time is an essential dimension in geological research,acting as a pivotal attribute that integrates data across various subdisciplines.The Geologic Time Scale(GTS)provides a formal framework for interpreting and communicating geologic time within the field of geological studies,such as macro-geological evolution and regional geologic surveys.展开更多
The spleen and stomach are the foundation of acquired constitution, and the source of qi and blood production. Therefore, harmonizing the spleen and stomach is of great importance in treatment of diseases. In this pap...The spleen and stomach are the foundation of acquired constitution, and the source of qi and blood production. Therefore, harmonizing the spleen and stomach is of great importance in treatment of diseases. In this paper, based on GAO＇s academic ideas of acupuncture and moxibustion, the different rules of harmonizing the spleen and stomach for internal miscellaneous diseases and carefully supplementing spleen and stomach for externally-contracted diseases were elaborated by starting with the acupoint selection prescriptions and harmonizing the spleen and stomach. In addition, time acupuncture and pattern differentiation moxibustion application and other treatment characteristics were put forward. The experience of professor GAO Yu-chun in acupuncture manipulation of ＂harmonizing the spleen and stomach＂ was summarized in detail from five aspects for learning and reference.展开更多
With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireles...With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireless networks,this article aims to unify the existing infrared,visible light,and ultraviolet subbands while also exploring the potential of the Petahertz(PHz)band to support extremely bandwidth-thirsfy telepresence style applications.Our focus is on the emerging Petahertz Communication(PetaCom)framework,scenario-dependent propagation channels,modulation schemes,system performance,multiple access techniques,and networking.We conclude with a range of PetaCom challenges and open research issues.展开更多
To summarize professor Pei9s experience in treating globus hystericus.Methods:Learn from your teacher.Results:Professor Pei had been suffering from the disease for more than 30 years and had her unique views on the tr...To summarize professor Pei9s experience in treating globus hystericus.Methods:Learn from your teacher.Results:Professor Pei had been suffering from the disease for more than 30 years and had her unique views on the treatment of globus hystericus,which are mostly for emotional dysfunction,liver Qi is not comfortable,functioning of Qi is not adjusted,Yin and Yang imbalance.The basic principle of treatment is to grasp the core pathogenesis,take harmony as the method and balance as the duration,harmonize Qi,regulate Yin and Yang,use drugs to disperse the liver and rectify Qi,as well as auxiliary treatment with products to promote blood circulation,remove blood stasis,dryness and dampness,and clear heat.展开更多
Minor Bupleurum Decoction is a common TCM compound and a classic prescription that can best reflect the"harmonizing method',of TCM.But there are many differences on the usage and dosage of Minor Bupleurum Dec...Minor Bupleurum Decoction is a common TCM compound and a classic prescription that can best reflect the"harmonizing method',of TCM.But there are many differences on the usage and dosage of Minor Bupleurum Decoction.Combined with the clinical treatment experience,this paper summarizes the experience of Minor Bupleurum Decoction in the clinical treatment of diseases.It is hoped that relevant suggestions can be provided for clinicians to improve the clinical therapeutic effect of Minor Bupleurum Decoction.展开更多
This paper approaches melody harmonization with piano accompaniment as a machine learning task, in a probabilistic framework. An existing Sample score set of Chinese folk song with piano accompaniment is used to build...This paper approaches melody harmonization with piano accompaniment as a machine learning task, in a probabilistic framework. An existing Sample score set of Chinese folk song with piano accompaniment is used to build a model of piano accomimniment process. The mcdel can then be used to harmonize new mclody with piano accompaniment.展开更多
The generation of optical vortices from nonlinear photonic crystals(NPCs)with spatially modulated second-order nonlinearity offers a promising approach to extend the working wavelength and topological charge of vortex...The generation of optical vortices from nonlinear photonic crystals(NPCs)with spatially modulated second-order nonlinearity offers a promising approach to extend the working wavelength and topological charge of vortex beams for various applications.In this work,the second harmonic(SH)optical vortex beams generated from nonlinear fork gratings under Gaussian beam illumination are numerically investigated.The far-field intensity and phase distributions,as well as the orbital angular momentum(OAM)spectra of the SH beams,are analyzed for different structural topological charges and diffraction orders.Results reveal that higher-order diffraction and larger structural topological charges lead to angular interference patterns and non-uniform intensity distributions,deviating from the standard vortex profile.To optimize the SH vortex quality,the effects of the fundamental wave beam waist,crystal thickness,and grating duty cycle are explored.It is shown that increasing the beam waist can effectively suppress diffraction order interference and improve the beam’s quality.This study provides theoretical guidance for enhancing the performance of nonlinear optical devices based on NPCs.展开更多
Spherical harmonic analysis(SHA)and synthesis(SHS)are widely used by researchers in various fields.Both numerical integration and least-squares methods can be employed for analysis and synthesis.However,these approach...Spherical harmonic analysis(SHA)and synthesis(SHS)are widely used by researchers in various fields.Both numerical integration and least-squares methods can be employed for analysis and synthesis.However,these approaches,when calculated via summation,are computationally intensive.Although the Fast Fourier Transform(FFT)algorithm is efficient,it is traditionally limited to processing global grid points starting from zero longitude.In this paper,we derive an improved FFT algorithm for spherical harmonic analysis and synthesis.The proposed algorithm eliminates the need for grid points to start at zero longitude,thereby expanding the applicability of FFT-based methods.Numerical experiments demonstrate that the new algorithm retains the computational efficiency of conventional FFT while achieving accuracy comparable to the summation method.Consequently,it enables direct harmonic coefficient calculation from global grid data without requiring interpolation to align with zero longitude.Additionally,the algrithm can generate grid points with equi-angular spacing using the improved FFT algorithm,starting from non-zero longitudes.To address the loss of orthogonality in latitude due to discrete spherical grids,a quadrature weight factor-dependent on grid type(e.g.,regular or Gauss grid)-is incorporated,as summarized in this study.展开更多
Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bu...Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bulkiness of the device.In this work,we present a comprehensive theoretical and numerical investigation of the simultaneous generation and competition between the second harmonic waves(SHW)and the third harmonic waves(THW)in a single nonlinear crystal.Through analyzing both small-signal and large-signal regimes,we reveal the complex coupling mechanisms between SHW and THW generation processes.Using periodically poled lithium niobate as an example,we demonstrate that the relative conversion efficiencies between SHW and THW can be freely adjusted by controlling the input fundamental wave power.This work provides new insights for designing efficient frequency converters capable of generating both SHW and THW outputs with controllable intensity ratios.展开更多
This study examines the high-order harmonic radiation behavior of MgO crystals driven by combined pulses based on the numerical solution of the semiconductor Bloch equation.We found that compared with the monochromati...This study examines the high-order harmonic radiation behavior of MgO crystals driven by combined pulses based on the numerical solution of the semiconductor Bloch equation.We found that compared with the monochromatic pulse,the MgO crystal can radiate a continuous harmonic spectrum with two platforms driven by the three-color combined pulse.The reason is that under the three-color combined pulse,the electron ionization and recombination can be effectively controlled within a half-optical cycle of the laser pulse.Using this continuous spectrum,we synthesized an isolated attosecond pulse with a duration of approximately 370 as.This study provides a new perspective on all-solid-state compact optical devices.展开更多
The integration of a large number of power electronic converters,such as railway power conditioner(RPC),introduces a series of problems,including harmonic interaction,stability issues,and wideband resonance,into the r...The integration of a large number of power electronic converters,such as railway power conditioner(RPC),introduces a series of problems,including harmonic interaction,stability issues,and wideband resonance,into the railway power supply system.To address these challenges,this paper proposes a novel harmonic resonance prevention measure for RPC-network-train interaction system.Firstly,a harmonic model,a parallel resonance impedance model,a series resonance admittance model,and a control stability model are each established for the RPC-network-train interaction system.Secondly,a comprehensive resonance impact factor(CRIF)is proposed to efficiently and accurately identify the key components affecting resonance,and to provide the selection results of optimization parameters for resonance prevention.Next,the initially selected parameters are constrained by the requirements of ripple current,reactive power and stability.Subsequently,the impedance parameters(control parameters and filter parameters)of the RPC are optimized with the objective of reshaping the parallel resonance impedance and series resonance admittance of the RPC-network-train interaction system,ensuring the output current har-monics of RPC meet standards to achieve resonance prevention,while ensuring the stable operation of the RPC.Finally,the proposed resonance prevention measure is verified under both light load and heavy load conditions using a simulation platform and a hardware-in-the-loop experimental platform.展开更多
This study systematically investigates the attractor characteristics of harmonic solitons in a passively modelocked fiber laser.Through comprehensive analysis in both time and frequency domains,we examine the evolutio...This study systematically investigates the attractor characteristics of harmonic solitons in a passively modelocked fiber laser.Through comprehensive analysis in both time and frequency domains,we examine the evolution of pulse width,spectral bandwidth,and energy across different harmonic orders.The results demonstrate typical soliton attractor behaviors,including attractiveness,dissipativity,and self-organization.In the transition regions between harmonic orders,breathing harmonic soliton states are captured using the time-stretched dispersive Fourier transform.By comparing the breathing dynamics with the stable states,the existence and self-organizing nature of soliton attractors are further confirmed.Finally,harmonic soliton attractors are employed as programmable light sources to achieve ternary optical coding.展开更多
This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common...This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common miniaturization technique to replace the conventional quarter-wavelength transmission line with an equivalent low-pass filter loaded with parallel coupled line and radial stubs. Since the latter leads to produce higher order harmonics, parasitic open-ended stubs are then properly introduced in the structure not only to overcome the issue but also to produce controllable transmission zeros. A versatile analytical model is also developed taking into account manufacturing restrictions, which makes it possible to extract the physical parameters of the coupler unit-cell for a given desired compactness percentage with respect to the conventional rat-race coupler. A prototype is fabricated and measured to validate the design,demonstrating the predicted behavior fairly achieved by numerical analysis. A significant size reduction of about 86.1% was achieved compared to the conventional design, while effectively suppressing higher order modes up to 23.4 GHz(including the 13th harmonic based on |S11|>-5 dB and |S21|<-17 dB)with high isolation level(|S41|<-17 dB) between the ports.展开更多
We theoretically investigate the elliptical high-order harmonic generation from H_(2)^(+)in two-color cross-linearlypolarized laser fields by numerically solving the two-dimensional time-dependent Schr¨odinger eq...We theoretically investigate the elliptical high-order harmonic generation from H_(2)^(+)in two-color cross-linearlypolarized laser fields by numerically solving the two-dimensional time-dependent Schr¨odinger equation.Numerical simulations show that the crossing-angle-dependent harmonic ellipticity exhibits a prominent antisymmetric structure,which tends to disappear as the internuclear distance increases.Furthermore,ground-state electrons experience resonant transitions to the first excited state at larger internuclear distances,where the disruption of symmetric electron motion suppresses the antisymmetric structure.Additionally,a near-circularly-polarized attosecond pulse can be obtained by modulating the crossing angle.展开更多
Molecular high-order harmonic spectroscopy is a significant advancement in ultrafast science, enabling the measurement of multielectron dynamics with attosecond temporal resolution. The fine structures observed in the...Molecular high-order harmonic spectroscopy is a significant advancement in ultrafast science, enabling the measurement of multielectron dynamics with attosecond temporal resolution. The fine structures observed in the molecular harmonic spectrum provide crucial insights into the structural or multielectron dynamical effects induced by intense laser fields. In this study, we measure the high-order harmonic spectrum of aligned CO_(2) molecules contributed from short trajectories. Two distinct groups of minima are identified in the plateau region. Our findings indicate that the deeper-lying molecular orbitals and two-center interference play significant roles in molecular harmonic generation. The results pave the way for advancing the understanding of multielectron dynamics in polyatomic molecules under intense laser fields.展开更多
Second harmonic generation(SHG),a fundamental and widely-studied phenomenon in nonlinear optics,has attracted significant attention for its ability to convert fundamental frequencies into their second harmonics.While ...Second harmonic generation(SHG),a fundamental and widely-studied phenomenon in nonlinear optics,has attracted significant attention for its ability to convert fundamental frequencies into their second harmonics.While the dominant SHG research has been focused on the optical and infrared regimes,its investigation in the microwave range presents challenges due to the requirements of materials with higher nonlinear coefficients and high-power microwave sources.Here,we provide an overview of methods together with underlying mechanisms for SHG in microwave frequencies,and discuss prospects and insights into the future developments of SHG-based technologies.The discussions on both numerical analyses and experimental studies will offer guidance for further SHG research and communication advancements in microwave regime.展开更多
This paper establishes an amplitude modulation heating model, simulating the far-field radiation of ELF/VLF signals generated by modulation heating, as well as the specific location and longitudinal extent of the radi...This paper establishes an amplitude modulation heating model, simulating the far-field radiation of ELF/VLF signals generated by modulation heating, as well as the specific location and longitudinal extent of the radiation source. We consider various modulation waveforms and find that square-wave modulation has the highest excitation efficiency for ELF/VLF signals, and that square-wave modulation with a smaller duty cycle(<50%) exhibits higher excitation efficiency for ELF/VLF signals, while the sin^(2)t waveform modulation yields the lowest proportion of harmonic energy in the generated signals. The amplitude of the second harmonic generated by the sin^(2)t waveform is less than one-tenth that of the fundamental frequency, and the energy of higher-frequency harmonics can be negligibly small compared with those of the fundamental wave. It is a challenging task to achieve a balance between enhancing the excitation efficiency of ELF/VLF signals and also suppressing harmonics generated by the modulated heating process. This is because the harmonics are correspondingly enhanced as the excitation efficiency of the signals is increased. However, we find that under conditions of varying effective radiant power and modulation frequency, as long as the modulation waveform is unchanged, the energy ratio between the fundamental frequency signal generated by modulated heating and each harmonic is relatively fixed, with changes only in signal intensity and the location of the radiation source zone. This implies that one can first select modulation waveforms that make the signal less prone to distortion, then increase the effective radiated power to enhance the signal strength, without concern for harmonic interference of the fundamental signal.展开更多
In this paper,a 12/14-pole permanent magnet in-wheel motor is studied for potential in-wheel application,and the torque and loss are improved simultaneously based on designing and optimizing the corresponding dominant...In this paper,a 12/14-pole permanent magnet in-wheel motor is studied for potential in-wheel application,and the torque and loss are improved simultaneously based on designing and optimizing the corresponding dominant harmonics.The key of this study is to evaluate the contributions of harmonics on torque and loss,and further determines the harmonics related to them.Based on this,the torque enhancement factor and loss suppression factor are defined based on the selected dominant harmonics.And,the two factors are set as the optimization objectives,aiming at improving the characteristics of torque and loss.At the same time,to achieve an efficient optimization,a layered optimization method is presented,which includes magnet source layer and permeance layer.Based on the optimization,the motor torque is improved effectively,while the rotor iron loss is also reduced significantly.Then,a prototype motor is manufactured for experimental test.Finally,the simulation analysis and test results verify the validation of the studied motor and the proposed optimization method based on dominant harmonics.展开更多
基金2024 Scientific Research Project of Jilin Provincial Administration of Traditional Chinese Medicine(Project No.:2024139)。
文摘Objective:To observe the clinical efficacy of the method of softening the liver,harmonizing the spleen,and unblocking the orifices in the treatment of Xiaoke Neizhang with Qi and Yin deficiency type.Methods:Seventy-two patients with Xiaoke Neizhang of qi and yin deficiency type were selected from March 2024 to May 2025 and divided into a treatment group and a control group with 36 cases each according to the random number table method.The treatment group was treated with the method of softening the liver,harmonizing the spleen,and unblocking the orifices,which included oral administration of Softening the Liver and Harmonizing the Spleen Pills combined with iontophoresis of Xuesaitong Injection.The control group was treated with oral administration of calcium dobesilate capsules.Both groups were treated for 2 courses,and multiple indicators such as visual acuity,fundus condition,and TCM syndrome scores were compared between the two groups.Results:The total effective rate of the treatment group was higher than that of the control group.There were significant differences in visual acuity,fundus condition,and TCM syndrome scores between and within the groups(P<0.05).Conclusion:The method of softening the liver,harmonizing the spleen,and unblocking the orifices has a definite clinical effect in the treatment of Xiaoke Neizhang with Qi and Yin deficiency type.It has a direct effect,is painless,easy for patients to accept,and has high clinical application value.
基金supported by the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project of China(Grant number:2024ZD1001105)National Natural Science Foundation of China(Grant number:42488201).
文摘Geologic time is an essential dimension in geological research,acting as a pivotal attribute that integrates data across various subdisciplines.The Geologic Time Scale(GTS)provides a formal framework for interpreting and communicating geologic time within the field of geological studies,such as macro-geological evolution and regional geologic surveys.
基金Supported by Project of Hebei Provincial Science and Technology Department:“Clinical study of the acupuncture manipulation of regulating governor vessel and unblocking brain in treatment of dominant diseases of acupuncture-moxibustion”:14277706D2014 project of scientific research on traditional Chinese medicine of Hebei Provincial Administration of Traditional Chinese Medicine“Study of GAO’s academic ideas of acupuncture and moxibustion”:2014038
文摘The spleen and stomach are the foundation of acquired constitution, and the source of qi and blood production. Therefore, harmonizing the spleen and stomach is of great importance in treatment of diseases. In this paper, based on GAO＇s academic ideas of acupuncture and moxibustion, the different rules of harmonizing the spleen and stomach for internal miscellaneous diseases and carefully supplementing spleen and stomach for externally-contracted diseases were elaborated by starting with the acupoint selection prescriptions and harmonizing the spleen and stomach. In addition, time acupuncture and pattern differentiation moxibustion application and other treatment characteristics were put forward. The experience of professor GAO Yu-chun in acupuncture manipulation of ＂harmonizing the spleen and stomach＂ was summarized in detail from five aspects for learning and reference.
基金supported by the Key Program of the National Natural Science Foundation of China(No.61631018),Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-JSC003)Strategic Priority Research Program of CAS(No.XDA22000000).L.Hanzo would like to acknowledge the financial support of the Engineering and Physical Sciences Research Council projects EP/P034284/1 and EP/P003990/1(COALESCE)as well as of the European Research Council’s Advanced Fellow Grant QuantCom(Grant No.789028).
文摘With the rapid deployment of Next-Generation Networks(NGN),the research community has initiated discussions on an entirely new suite of optical enabling techniques.To pave the way for the development of future wireless networks,this article aims to unify the existing infrared,visible light,and ultraviolet subbands while also exploring the potential of the Petahertz(PHz)band to support extremely bandwidth-thirsfy telepresence style applications.Our focus is on the emerging Petahertz Communication(PetaCom)framework,scenario-dependent propagation channels,modulation schemes,system performance,multiple access techniques,and networking.We conclude with a range of PetaCom challenges and open research issues.
文摘To summarize professor Pei9s experience in treating globus hystericus.Methods:Learn from your teacher.Results:Professor Pei had been suffering from the disease for more than 30 years and had her unique views on the treatment of globus hystericus,which are mostly for emotional dysfunction,liver Qi is not comfortable,functioning of Qi is not adjusted,Yin and Yang imbalance.The basic principle of treatment is to grasp the core pathogenesis,take harmony as the method and balance as the duration,harmonize Qi,regulate Yin and Yang,use drugs to disperse the liver and rectify Qi,as well as auxiliary treatment with products to promote blood circulation,remove blood stasis,dryness and dampness,and clear heat.
文摘Minor Bupleurum Decoction is a common TCM compound and a classic prescription that can best reflect the"harmonizing method',of TCM.But there are many differences on the usage and dosage of Minor Bupleurum Decoction.Combined with the clinical treatment experience,this paper summarizes the experience of Minor Bupleurum Decoction in the clinical treatment of diseases.It is hoped that relevant suggestions can be provided for clinicians to improve the clinical therapeutic effect of Minor Bupleurum Decoction.
基金National Natural Science Foundation of China (No.60975076)
文摘This paper approaches melody harmonization with piano accompaniment as a machine learning task, in a probabilistic framework. An existing Sample score set of Chinese folk song with piano accompaniment is used to build a model of piano accomimniment process. The mcdel can then be used to harmonize new mclody with piano accompaniment.
基金supported by the National Nat-ural Science Foundation of China(Nos.12192251,12174185,92163216,and 62288101).
文摘The generation of optical vortices from nonlinear photonic crystals(NPCs)with spatially modulated second-order nonlinearity offers a promising approach to extend the working wavelength and topological charge of vortex beams for various applications.In this work,the second harmonic(SH)optical vortex beams generated from nonlinear fork gratings under Gaussian beam illumination are numerically investigated.The far-field intensity and phase distributions,as well as the orbital angular momentum(OAM)spectra of the SH beams,are analyzed for different structural topological charges and diffraction orders.Results reveal that higher-order diffraction and larger structural topological charges lead to angular interference patterns and non-uniform intensity distributions,deviating from the standard vortex profile.To optimize the SH vortex quality,the effects of the fundamental wave beam waist,crystal thickness,and grating duty cycle are explored.It is shown that increasing the beam waist can effectively suppress diffraction order interference and improve the beam’s quality.This study provides theoretical guidance for enhancing the performance of nonlinear optical devices based on NPCs.
基金supported by The National Natural Science Foundation of China(42374004).
文摘Spherical harmonic analysis(SHA)and synthesis(SHS)are widely used by researchers in various fields.Both numerical integration and least-squares methods can be employed for analysis and synthesis.However,these approaches,when calculated via summation,are computationally intensive.Although the Fast Fourier Transform(FFT)algorithm is efficient,it is traditionally limited to processing global grid points starting from zero longitude.In this paper,we derive an improved FFT algorithm for spherical harmonic analysis and synthesis.The proposed algorithm eliminates the need for grid points to start at zero longitude,thereby expanding the applicability of FFT-based methods.Numerical experiments demonstrate that the new algorithm retains the computational efficiency of conventional FFT while achieving accuracy comparable to the summation method.Consequently,it enables direct harmonic coefficient calculation from global grid data without requiring interpolation to align with zero longitude.Additionally,the algrithm can generate grid points with equi-angular spacing using the improved FFT algorithm,starting from non-zero longitudes.To address the loss of orthogonality in latitude due to discrete spherical grids,a quadrature weight factor-dependent on grid type(e.g.,regular or Gauss grid)-is incorporated,as summarized in this study.
基金supported by the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)+1 种基金the National Key Research and Development Program of China(Grant No.2023YFA1406900)the Fund of the National Postdoctoral Researcher Program(Grant No.GZB20240785).
文摘Conventional approaches for obtaining the second and third harmonics typically employ several nonlinear crystals to generate them,which is restricted in application due to the complexity of the optical path and the bulkiness of the device.In this work,we present a comprehensive theoretical and numerical investigation of the simultaneous generation and competition between the second harmonic waves(SHW)and the third harmonic waves(THW)in a single nonlinear crystal.Through analyzing both small-signal and large-signal regimes,we reveal the complex coupling mechanisms between SHW and THW generation processes.Using periodically poled lithium niobate as an example,we demonstrate that the relative conversion efficiencies between SHW and THW can be freely adjusted by controlling the input fundamental wave power.This work provides new insights for designing efficient frequency converters capable of generating both SHW and THW outputs with controllable intensity ratios.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.Y23A040001)the National Natural Science Foundation of China(Grant Nos.12374029,12074145,and 11975012)+4 种基金the National Key Research and Development Program of China(Grant No.2019YFA0307700)the Research Foundation for Basic Research of Jilin ProvinceChina(Grant No.20220101003JC)the National College Students Innovation and Entrepreneurship Training Program(Grant No.202310350062)the Graduate Innovation Fund of Jilin University(Grant No.2024CX041)。
文摘This study examines the high-order harmonic radiation behavior of MgO crystals driven by combined pulses based on the numerical solution of the semiconductor Bloch equation.We found that compared with the monochromatic pulse,the MgO crystal can radiate a continuous harmonic spectrum with two platforms driven by the three-color combined pulse.The reason is that under the three-color combined pulse,the electron ionization and recombination can be effectively controlled within a half-optical cycle of the laser pulse.Using this continuous spectrum,we synthesized an isolated attosecond pulse with a duration of approximately 370 as.This study provides a new perspective on all-solid-state compact optical devices.
基金supported in part by the National Natural Science Foundation of China under Grant No.52277126.
文摘The integration of a large number of power electronic converters,such as railway power conditioner(RPC),introduces a series of problems,including harmonic interaction,stability issues,and wideband resonance,into the railway power supply system.To address these challenges,this paper proposes a novel harmonic resonance prevention measure for RPC-network-train interaction system.Firstly,a harmonic model,a parallel resonance impedance model,a series resonance admittance model,and a control stability model are each established for the RPC-network-train interaction system.Secondly,a comprehensive resonance impact factor(CRIF)is proposed to efficiently and accurately identify the key components affecting resonance,and to provide the selection results of optimization parameters for resonance prevention.Next,the initially selected parameters are constrained by the requirements of ripple current,reactive power and stability.Subsequently,the impedance parameters(control parameters and filter parameters)of the RPC are optimized with the objective of reshaping the parallel resonance impedance and series resonance admittance of the RPC-network-train interaction system,ensuring the output current har-monics of RPC meet standards to achieve resonance prevention,while ensuring the stable operation of the RPC.Finally,the proposed resonance prevention measure is verified under both light load and heavy load conditions using a simulation platform and a hardware-in-the-loop experimental platform.
基金supported by the National Natural Science Foundation of China(Grant No.12475008)the Scientific Research and Developed Fund of Zhejiang A&F University(Grant No.2021FR0009)。
文摘This study systematically investigates the attractor characteristics of harmonic solitons in a passively modelocked fiber laser.Through comprehensive analysis in both time and frequency domains,we examine the evolution of pulse width,spectral bandwidth,and energy across different harmonic orders.The results demonstrate typical soliton attractor behaviors,including attractiveness,dissipativity,and self-organization.In the transition regions between harmonic orders,breathing harmonic soliton states are captured using the time-stretched dispersive Fourier transform.By comparing the breathing dynamics with the stable states,the existence and self-organizing nature of soliton attractors are further confirmed.Finally,harmonic soliton attractors are employed as programmable light sources to achieve ternary optical coding.
文摘This paper presents a novel approach to design a compact circular rat-race coupler with an ultrawide stopband, with the aim to reduce its size while maintaining performance. The design methodology begins with a common miniaturization technique to replace the conventional quarter-wavelength transmission line with an equivalent low-pass filter loaded with parallel coupled line and radial stubs. Since the latter leads to produce higher order harmonics, parasitic open-ended stubs are then properly introduced in the structure not only to overcome the issue but also to produce controllable transmission zeros. A versatile analytical model is also developed taking into account manufacturing restrictions, which makes it possible to extract the physical parameters of the coupler unit-cell for a given desired compactness percentage with respect to the conventional rat-race coupler. A prototype is fabricated and measured to validate the design,demonstrating the predicted behavior fairly achieved by numerical analysis. A significant size reduction of about 86.1% was achieved compared to the conventional design, while effectively suppressing higher order modes up to 23.4 GHz(including the 13th harmonic based on |S11|>-5 dB and |S21|<-17 dB)with high isolation level(|S41|<-17 dB) between the ports.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974229,12204291,and 11404204)the Fund from Graduate Students of Shanxi Normal University,China(Grant No.2023XSY044).
文摘We theoretically investigate the elliptical high-order harmonic generation from H_(2)^(+)in two-color cross-linearlypolarized laser fields by numerically solving the two-dimensional time-dependent Schr¨odinger equation.Numerical simulations show that the crossing-angle-dependent harmonic ellipticity exhibits a prominent antisymmetric structure,which tends to disappear as the internuclear distance increases.Furthermore,ground-state electrons experience resonant transitions to the first excited state at larger internuclear distances,where the disruption of symmetric electron motion suppresses the antisymmetric structure.Additionally,a near-circularly-polarized attosecond pulse can be obtained by modulating the crossing angle.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92250306 and 12304302)the Natural Science Foundation of Jilin Province, China (Grant Nos. YDZJ202101ZYTS157 and YDZJ202201ZYTS314)the Scientific Research Foundation of Jilin Province Education Department, China (Grant No. JJKH20230283KJ)。
文摘Molecular high-order harmonic spectroscopy is a significant advancement in ultrafast science, enabling the measurement of multielectron dynamics with attosecond temporal resolution. The fine structures observed in the molecular harmonic spectrum provide crucial insights into the structural or multielectron dynamical effects induced by intense laser fields. In this study, we measure the high-order harmonic spectrum of aligned CO_(2) molecules contributed from short trajectories. Two distinct groups of minima are identified in the plateau region. Our findings indicate that the deeper-lying molecular orbitals and two-center interference play significant roles in molecular harmonic generation. The results pave the way for advancing the understanding of multielectron dynamics in polyatomic molecules under intense laser fields.
基金supported by the National Natural Science Foun-dation of China(No.12274339).
文摘Second harmonic generation(SHG),a fundamental and widely-studied phenomenon in nonlinear optics,has attracted significant attention for its ability to convert fundamental frequencies into their second harmonics.While the dominant SHG research has been focused on the optical and infrared regimes,its investigation in the microwave range presents challenges due to the requirements of materials with higher nonlinear coefficients and high-power microwave sources.Here,we provide an overview of methods together with underlying mechanisms for SHG in microwave frequencies,and discuss prospects and insights into the future developments of SHG-based technologies.The discussions on both numerical analyses and experimental studies will offer guidance for further SHG research and communication advancements in microwave regime.
基金supported by the National Key R&D Program of China (No. 2022YFE0204100)the National Natural Science Foundation of China (12205067 and 12375199)the Fundamental Research Funds for the Central Universities (Grant No. HIT.OCEF. 2022036)。
文摘This paper establishes an amplitude modulation heating model, simulating the far-field radiation of ELF/VLF signals generated by modulation heating, as well as the specific location and longitudinal extent of the radiation source. We consider various modulation waveforms and find that square-wave modulation has the highest excitation efficiency for ELF/VLF signals, and that square-wave modulation with a smaller duty cycle(<50%) exhibits higher excitation efficiency for ELF/VLF signals, while the sin^(2)t waveform modulation yields the lowest proportion of harmonic energy in the generated signals. The amplitude of the second harmonic generated by the sin^(2)t waveform is less than one-tenth that of the fundamental frequency, and the energy of higher-frequency harmonics can be negligibly small compared with those of the fundamental wave. It is a challenging task to achieve a balance between enhancing the excitation efficiency of ELF/VLF signals and also suppressing harmonics generated by the modulated heating process. This is because the harmonics are correspondingly enhanced as the excitation efficiency of the signals is increased. However, we find that under conditions of varying effective radiant power and modulation frequency, as long as the modulation waveform is unchanged, the energy ratio between the fundamental frequency signal generated by modulated heating and each harmonic is relatively fixed, with changes only in signal intensity and the location of the radiation source zone. This implies that one can first select modulation waveforms that make the signal less prone to distortion, then increase the effective radiated power to enhance the signal strength, without concern for harmonic interference of the fundamental signal.
文摘In this paper,a 12/14-pole permanent magnet in-wheel motor is studied for potential in-wheel application,and the torque and loss are improved simultaneously based on designing and optimizing the corresponding dominant harmonics.The key of this study is to evaluate the contributions of harmonics on torque and loss,and further determines the harmonics related to them.Based on this,the torque enhancement factor and loss suppression factor are defined based on the selected dominant harmonics.And,the two factors are set as the optimization objectives,aiming at improving the characteristics of torque and loss.At the same time,to achieve an efficient optimization,a layered optimization method is presented,which includes magnet source layer and permeance layer.Based on the optimization,the motor torque is improved effectively,while the rotor iron loss is also reduced significantly.Then,a prototype motor is manufactured for experimental test.Finally,the simulation analysis and test results verify the validation of the studied motor and the proposed optimization method based on dominant harmonics.
