We study the temperature T and the phase of the Josephson critical current I（Ф） by taking into account the roughness scattering effect at inerface in an f-wave superconductor （S）/Insulator layer （I）/f-wave supe...We study the temperature T and the phase of the Josephson critical current I（Ф） by taking into account the roughness scattering effect at inerface in an f-wave superconductor （S）/Insulator layer （I）/f-wave superconductor （S） junction. It is found that the Josephson critical currents in f-wave Sir-wave S, the barrier strength and the roughness strength at inerface always suppress the Andreev reflection. When α=β, the phase dependence of the Josephson current I（Ф） between two f-wave S is predicted to be sin Ф; particularly, when a α≠ β, the phase dependence of the Josephson current I（Ф） between two f-wave superconductors is not predicted to be sin Ф and with the barrier strength increasing, the period of the I（Ф） turns decrease.展开更多
Within the Born-Oppenheimer(BO)approximation,nuclear motions of a molecule are often envisioned to occur on an adiabatic potential energy surface(PES).However,this single PES picture should be reconsidered if a conica...Within the Born-Oppenheimer(BO)approximation,nuclear motions of a molecule are often envisioned to occur on an adiabatic potential energy surface(PES).However,this single PES picture should be reconsidered if a conical intersection(CI)is present,although the energy is well below the CI.The presence of the CI results in two additional terms in the nuclear Hamiltonian in the adiabatic presentation,i.e.,the diagonal BO correction(DBOC)and the geometric phase(GP),which are divergent at the CI.At the same time,there are cusps in the adiabatic PESs.Thus usually it is regarded that there is numerical difficulty in a quantum dynamics calculation for treating CI in the adiabatic representation.A popular numerical method in nuclear quantum dynamics calculations is the Sinc discrete variable representation(DVR)method.We examine the numerical accuracy of the Sinc DVR method for solving the Schrodinger equation of a two dimensional model of two electronic states with a CI in both the adiabatic and diabatic representation.The results suggest that the Sinc DVR method is capable of giving reliable results in the adiabatic representation with usual density of the grid points,without special treatment of the divergence of the DBOC and the GP.The numerical uncertainty is not worse than that after the introduction of an arbitrary vector potential for accounting the GP,whose accurate form usually is not easy to obtain.展开更多
Absrtact: The principle of ZVS - PWM inverting circuit is first described by means of inverting welder supply. The contrastive study is made on switching characte -ristics and switching losses of IGBT between ZVS - PW...Absrtact: The principle of ZVS - PWM inverting circuit is first described by means of inverting welder supply. The contrastive study is made on switching characte -ristics and switching losses of IGBT between ZVS - PWM and hard - switching.展开更多
The nonadiabatic dynamics of methyl nitrate(CH_(3)ONO_(2))is studied with the on-the-fy trajectory surface hopping dynamics at the ADC(2)level.The results confirmed the existence of the ultrafast nonadiabatic decay to...The nonadiabatic dynamics of methyl nitrate(CH_(3)ONO_(2))is studied with the on-the-fy trajectory surface hopping dynamics at the ADC(2)level.The results confirmed the existence of the ultrafast nonadiabatic decay to the electronic ground state.When the dynamics starts from S_(1) and S_(2),the photoproducts are CH_(3)O+NO_(2),consistent with previous results obtained from the experimental studies and theoretical dynamics simulations at more accurate XMS-CASPT2 level.The photolysis products are CH_(3)O+NO_(2) at the ADC(2)level when the dynamics starts from S3,while different photolysis products were obtained in previous experimental and theoretical works.These results demonstrate that the ADC(2)method may still be useful for treating the photolysis mechanism of CH_(3)ONO_(2) at the long-wavelength UV excitation,while great caution should be paid due to its inaccurate performance in the description of the photolysis dynamics at the short-wavelength UV excitation.This gives valuable information to access the accuracy when other alkyl nitrates are treated at the ADC(2)level.展开更多
For converter transformer, AC-DC combined electric field can trigger space charge accumulation on oil-impregnated pressboard interface. The accumulation of space charge on oil-pressboard interface can result in electr...For converter transformer, AC-DC combined electric field can trigger space charge accumulation on oil-impregnated pressboard interface. The accumulation of space charge on oil-pressboard interface can result in electric field distortion, trend to trigger surface discharge of barriers. This paper studied the influence of surface charge on flashover voltage of oil-impregnated pressboard under AC-DC combined electric field. The study finds that the flashover voltage of oil-pressboard interface under negative polarity DC superimposed AC electric field is higher than that.of positive DC superimposed AC voltage to form composite electric field. It was found that homopolar surface charge has been accumulated on the interface of oil-pressboard with positive or negative DC voltage through measuring surface potential by the electrostatic capacitive probe. The surface charge produced electric field in the opposite direction, which weakening the synthetic electric field strength. What＇s more, under the same conditions, the negative surface charge density oil-pressboard is much larger than the positive.展开更多
The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant...The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant contributions from both the BornOppenheimer(BO)forbidden reaction F^(*)(^(2)P_(1/2))+HD→DF+H and the BO-allowed reaction F(^(2)P_(3/2))+HD→DF+H were observed.In the backward scattering direction,the contribution from the BO-forbidden reaction F^(*)(^(2)P_(1/2))+HD was found to be considerably greater than the BO-allowed reaction F(^(2)P_(3/2))+HD,indicating the non-adiabatic effects play an important role in the dynamics of the title reaction at low collision energies.Collision-energy dependence of differential cross sections(DCSs)in the backward scattering direction was found to be monotonously decreased as the collision energy decreases,which does not support the existence of resonance states in this energy range.DCSs of both BO-allowed and BO-forbidden reactions were measured at seven collision energies from 3.03 meV to 17.97 meV.It is quite unexpected that the angular distribution gradually shifts from backward to sideway as the collision energy decreases from 17.97 meV to 3.03 meV,suggesting some unknown mechanisms may exist at low collision energies.展开更多
A 15-stage axial-flow compressor utilized in steel industry was studied in this paper. All the stator's stagger angles of the compressor are variable to ensure the multistage compressor operate effectively within ...A 15-stage axial-flow compressor utilized in steel industry was studied in this paper. All the stator's stagger angles of the compressor are variable to ensure the multistage compressor operate effectively within a wide range of flow rate and meanwhile satisfy the demand for sufficient pressure ratio, adiabatic efficiency and stall margin. Three in all different base-settings of stator's stagger angles were presented and commercial CFD software was applied to obtain the overall performance characteristics. The results showed that both of the optimized base-settings improved the performances both in summer and winter conditions, although the adiabatic efficiency was somewhat decreased. Taking incidence angle and stage loading into consideration, differences among the three cases were analyzed in detail. On the basis of numerical computations, the performance could be effectively improved through adjusting the base-setting of stator's stagger angles.展开更多
In view of the high voltage, the strong magnetic field environment of the high-voltage switchgear, the system based on the optical wireless sensing technology, realizes the isolated contact temperature monitoring of t...In view of the high voltage, the strong magnetic field environment of the high-voltage switchgear, the system based on the optical wireless sensing technology, realizes the isolated contact temperature monitoring of the high-voltage switchgear. In this scheme, the good thermal conductivity and insulation ceramic materials were selected as the outer jacket material sensing probe, and the program had a good solution to the problem of high and low voltage isolation; The combination of the optical fiber composite insulators for wireless sensing, not only solves the problem of high voltage insulation, but also avoids the ＂creeping＂ phenomenon due to dust. The package of the structure and reasonable installation solves the cross sensitivity of strain. The application showed that the precision of temperature measurement of the system could reach ± 0.5 ℃ and could work in a variety of harsh environments. It could improve the reliability of the operation of the electrical equipment significantly and has considerable practical value for the whole power system.展开更多
Objective： To discuss the acupoints selection pattern in acupuncture-moxibustion treatment of perimenopausal syndrome（PMS） from 2007 to 2016. Methods： Clinical literatures related to PMS treated with acupuncture-m...Objective： To discuss the acupoints selection pattern in acupuncture-moxibustion treatment of perimenopausal syndrome（PMS） from 2007 to 2016. Methods： Clinical literatures related to PMS treated with acupuncture-moxibustion published from 2007 to 2016 were collected from Chinese Biomedical Literature Database（CBM）, Chongqing VIP Database（CQVIP）, China National Knowledge Infrastructure（CNKI）, and Wanfang Academic Journal Full-text Database（Wanfang）. The retrieved data underwent descriptive analysis, cluster analysis and association pattern analysis to determine the acupoints selection principle in acupuncture-moxibustion treatment of PMS. Results： The top five acupoints used in acupuncture-moxibustion treatment of PMS were Sanyinjiao（SP 6）, Shenshu（BL 23）, Guanyuan（CV 4）, Baihui（GV 20）, and Shenmen（HT 7）. The leading 4 meridians were Bladder Meridian, Conception Vessel, Spleen Meridian, and Governor Vessel. The clustering analysis showed that the 5 core acupoint groups were：（1） Sanyinjiao（SP 6）;（2） Shenshu（BL 23） and Guanyuan（CV 4）;（3） Baihui（GV 20）, Shenmen（HT 7）, Zusanli（ST 36）, Ganshu（BL 18） and Taichong（LR 3）;（4） Taixi（KI 3）, Pishu（BL 20）, Xinshu（BL 15）, Qihai（CV 6） and Neiguan（PC 6）;（5） Sishencong（EX-HN 1）, Zhongwan（CV 12）, Hegu（LI 4）, Yintang（GV 29）, Fengchi（GB 20）, Zhongji（CV 3） and Feishu（BL 13）. The three most significant acupoints were Sanyinjiao（SP 6）, Shenshu（BL 23） and Guanyuan（CV 4）. Acupoint groups based on syndrome differentiation included：（1） Hegu（LI 4）, Zhongwan（CV 12） and Sishencong（EX-HN 1）;（2） Feishu（BL 13）, Zhongji（CV 3）, Fengchi（GB 20） and Yintang（GV 29）;（3） Xinshu（BL 15）, Pishu（BL 20）, Qihai（CV 6）, Neiguan（PC 6） and Taixi（KI 3）;（4） Ganshu（BL 18）, Zusanli（ST 36）, Shenmen（HT 7）, Taichong（LR 3） and Baihui（GV 20）. The analysis of association pattern elaborated that Shenshu（BL 23） and Sanyinjiao（SP 6） won the highest support rate in the paired groups; Ganshu（BL 18）, Shenshu（BL 23） and Sanyinjiao（SP 6） had the highest support rate among the acupoint groups. Conclusion： The data mining results of acupuncture-moxibustion treatment of PMS substantially conform to the general principle in traditional acupuncture-moxibustion theories, able to reflect the acupoints selection and grouping pattern and provide references for acupuncture-moxibustion treatment of PMS.展开更多
Recent advances in non-radiative wireless power transfer(WPT)technique essentially relying on magnetic resonance and near-field coupling have successfully enabled a wide range of applications.However,WPT systems based...Recent advances in non-radiative wireless power transfer(WPT)technique essentially relying on magnetic resonance and near-field coupling have successfully enabled a wide range of applications.However,WPT systems based on double resonators are severely limited to short-or mid-range distance,due to the deteriorating efficiency and power with long transfer distance.WPT systems based on multi-relay resonators can overcome this problem,which,however,suffer from sensitivity to perturbations and fabrication imperfections.Here,we experimentally demonstrate a concept of topological wireless power transfer(TWPT),where energy is transferred efficiently via the near-field coupling between two topological edge states localized at the ends of a one-dimensional radiowave topological insulator.Such a TWPT system can be modelled as a parity-time-symmetric Su-Schrieffer-Heeger(SSH)chain with complex boundary potentials.Besides,the coil configurations are judiciously designed,which significantly suppress the unwanted cross-couplings between nonadjacent coils that could break the chiral symmetry of the SSH chain.By tuning the inter-and intra-cell coupling strengths,we theoretically and experimentally demonstrate high energy transfer efficiency near the exceptional point of the topological edge states,even in the presence of disorder.The combination of topological metamaterials,non-Hermitian physics,and WPT techniques could promise a variety of robust,efficient WPT applications over long distances in electronics,transportation,and industry.展开更多
基金Supported by the"333"Project Funds of Jiangsu Province of China,the National Natural Science Foundation of China under Grant No.20571029by the Program for Excellent Talents in Huangshi Institute of Technology
文摘We study the temperature T and the phase of the Josephson critical current I（Ф） by taking into account the roughness scattering effect at inerface in an f-wave superconductor （S）/Insulator layer （I）/f-wave superconductor （S） junction. It is found that the Josephson critical currents in f-wave Sir-wave S, the barrier strength and the roughness strength at inerface always suppress the Andreev reflection. When α=β, the phase dependence of the Josephson current I（Ф） between two f-wave S is predicted to be sin Ф; particularly, when a α≠ β, the phase dependence of the Josephson current I（Ф） between two f-wave superconductors is not predicted to be sin Ф and with the barrier strength increasing, the period of the I（Ф） turns decrease.
基金was supported by the National Natural Science Foundation of China(No.21733006 and No.21825303)NSFC Center for Chemical Dynamics(No.21688102)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB17000000)the Chinese Academy of Sciences,and the Key Research Program of the Chinese Academy of Sciences
文摘Within the Born-Oppenheimer(BO)approximation,nuclear motions of a molecule are often envisioned to occur on an adiabatic potential energy surface(PES).However,this single PES picture should be reconsidered if a conical intersection(CI)is present,although the energy is well below the CI.The presence of the CI results in two additional terms in the nuclear Hamiltonian in the adiabatic presentation,i.e.,the diagonal BO correction(DBOC)and the geometric phase(GP),which are divergent at the CI.At the same time,there are cusps in the adiabatic PESs.Thus usually it is regarded that there is numerical difficulty in a quantum dynamics calculation for treating CI in the adiabatic representation.A popular numerical method in nuclear quantum dynamics calculations is the Sinc discrete variable representation(DVR)method.We examine the numerical accuracy of the Sinc DVR method for solving the Schrodinger equation of a two dimensional model of two electronic states with a CI in both the adiabatic and diabatic representation.The results suggest that the Sinc DVR method is capable of giving reliable results in the adiabatic representation with usual density of the grid points,without special treatment of the divergence of the DBOC and the GP.The numerical uncertainty is not worse than that after the introduction of an arbitrary vector potential for accounting the GP,whose accurate form usually is not easy to obtain.
文摘Absrtact: The principle of ZVS - PWM inverting circuit is first described by means of inverting welder supply. The contrastive study is made on switching characte -ristics and switching losses of IGBT between ZVS - PWM and hard - switching.
基金supported by the National Natural Science Foundation of China(No.21933011,No.21873112)。
文摘The nonadiabatic dynamics of methyl nitrate(CH_(3)ONO_(2))is studied with the on-the-fy trajectory surface hopping dynamics at the ADC(2)level.The results confirmed the existence of the ultrafast nonadiabatic decay to the electronic ground state.When the dynamics starts from S_(1) and S_(2),the photoproducts are CH_(3)O+NO_(2),consistent with previous results obtained from the experimental studies and theoretical dynamics simulations at more accurate XMS-CASPT2 level.The photolysis products are CH_(3)O+NO_(2) at the ADC(2)level when the dynamics starts from S3,while different photolysis products were obtained in previous experimental and theoretical works.These results demonstrate that the ADC(2)method may still be useful for treating the photolysis mechanism of CH_(3)ONO_(2) at the long-wavelength UV excitation,while great caution should be paid due to its inaccurate performance in the description of the photolysis dynamics at the short-wavelength UV excitation.This gives valuable information to access the accuracy when other alkyl nitrates are treated at the ADC(2)level.
文摘For converter transformer, AC-DC combined electric field can trigger space charge accumulation on oil-impregnated pressboard interface. The accumulation of space charge on oil-pressboard interface can result in electric field distortion, trend to trigger surface discharge of barriers. This paper studied the influence of surface charge on flashover voltage of oil-impregnated pressboard under AC-DC combined electric field. The study finds that the flashover voltage of oil-pressboard interface under negative polarity DC superimposed AC electric field is higher than that.of positive DC superimposed AC voltage to form composite electric field. It was found that homopolar surface charge has been accumulated on the interface of oil-pressboard with positive or negative DC voltage through measuring surface potential by the electrostatic capacitive probe. The surface charge produced electric field in the opposite direction, which weakening the synthetic electric field strength. What＇s more, under the same conditions, the negative surface charge density oil-pressboard is much larger than the positive.
基金supported by the National Natural Science Foundation of China(No.21822305,No.21688102,No.22003067)the Chinese Academy of Sciences(No.XDB17000000)。
文摘The prototypical reaction of F+HD→DF+H was investigated at collision energies from 3.03 meV to 17.97 meV using a crossed molecular beam apparatus with multichannel Rydberg tagging time-of-flight detection.Significant contributions from both the BornOppenheimer(BO)forbidden reaction F^(*)(^(2)P_(1/2))+HD→DF+H and the BO-allowed reaction F(^(2)P_(3/2))+HD→DF+H were observed.In the backward scattering direction,the contribution from the BO-forbidden reaction F^(*)(^(2)P_(1/2))+HD was found to be considerably greater than the BO-allowed reaction F(^(2)P_(3/2))+HD,indicating the non-adiabatic effects play an important role in the dynamics of the title reaction at low collision energies.Collision-energy dependence of differential cross sections(DCSs)in the backward scattering direction was found to be monotonously decreased as the collision energy decreases,which does not support the existence of resonance states in this energy range.DCSs of both BO-allowed and BO-forbidden reactions were measured at seven collision energies from 3.03 meV to 17.97 meV.It is quite unexpected that the angular distribution gradually shifts from backward to sideway as the collision energy decreases from 17.97 meV to 3.03 meV,suggesting some unknown mechanisms may exist at low collision energies.
文摘A 15-stage axial-flow compressor utilized in steel industry was studied in this paper. All the stator's stagger angles of the compressor are variable to ensure the multistage compressor operate effectively within a wide range of flow rate and meanwhile satisfy the demand for sufficient pressure ratio, adiabatic efficiency and stall margin. Three in all different base-settings of stator's stagger angles were presented and commercial CFD software was applied to obtain the overall performance characteristics. The results showed that both of the optimized base-settings improved the performances both in summer and winter conditions, although the adiabatic efficiency was somewhat decreased. Taking incidence angle and stage loading into consideration, differences among the three cases were analyzed in detail. On the basis of numerical computations, the performance could be effectively improved through adjusting the base-setting of stator's stagger angles.
文摘In view of the high voltage, the strong magnetic field environment of the high-voltage switchgear, the system based on the optical wireless sensing technology, realizes the isolated contact temperature monitoring of the high-voltage switchgear. In this scheme, the good thermal conductivity and insulation ceramic materials were selected as the outer jacket material sensing probe, and the program had a good solution to the problem of high and low voltage isolation; The combination of the optical fiber composite insulators for wireless sensing, not only solves the problem of high voltage insulation, but also avoids the ＂creeping＂ phenomenon due to dust. The package of the structure and reasonable installation solves the cross sensitivity of strain. The application showed that the precision of temperature measurement of the system could reach ± 0.5 ℃ and could work in a variety of harsh environments. It could improve the reliability of the operation of the electrical equipment significantly and has considerable practical value for the whole power system.
基金supported by Scientific Research Project of Hebei Provincial Administration Bureau of Traditional Chinese Medicine,No.2015162Hebei Tangshan Science and Technology Project,No.14130264B+1 种基金Cultivation Fund of North China University of Science and Technology,No.GP201512Undergraduate Innovation and Entrepreneurship Training Programs of North China University of Science and Technology,No.X2015203,No.X2016281~~
文摘Objective： To discuss the acupoints selection pattern in acupuncture-moxibustion treatment of perimenopausal syndrome（PMS） from 2007 to 2016. Methods： Clinical literatures related to PMS treated with acupuncture-moxibustion published from 2007 to 2016 were collected from Chinese Biomedical Literature Database（CBM）, Chongqing VIP Database（CQVIP）, China National Knowledge Infrastructure（CNKI）, and Wanfang Academic Journal Full-text Database（Wanfang）. The retrieved data underwent descriptive analysis, cluster analysis and association pattern analysis to determine the acupoints selection principle in acupuncture-moxibustion treatment of PMS. Results： The top five acupoints used in acupuncture-moxibustion treatment of PMS were Sanyinjiao（SP 6）, Shenshu（BL 23）, Guanyuan（CV 4）, Baihui（GV 20）, and Shenmen（HT 7）. The leading 4 meridians were Bladder Meridian, Conception Vessel, Spleen Meridian, and Governor Vessel. The clustering analysis showed that the 5 core acupoint groups were：（1） Sanyinjiao（SP 6）;（2） Shenshu（BL 23） and Guanyuan（CV 4）;（3） Baihui（GV 20）, Shenmen（HT 7）, Zusanli（ST 36）, Ganshu（BL 18） and Taichong（LR 3）;（4） Taixi（KI 3）, Pishu（BL 20）, Xinshu（BL 15）, Qihai（CV 6） and Neiguan（PC 6）;（5） Sishencong（EX-HN 1）, Zhongwan（CV 12）, Hegu（LI 4）, Yintang（GV 29）, Fengchi（GB 20）, Zhongji（CV 3） and Feishu（BL 13）. The three most significant acupoints were Sanyinjiao（SP 6）, Shenshu（BL 23） and Guanyuan（CV 4）. Acupoint groups based on syndrome differentiation included：（1） Hegu（LI 4）, Zhongwan（CV 12） and Sishencong（EX-HN 1）;（2） Feishu（BL 13）, Zhongji（CV 3）, Fengchi（GB 20） and Yintang（GV 29）;（3） Xinshu（BL 15）, Pishu（BL 20）, Qihai（CV 6）, Neiguan（PC 6） and Taixi（KI 3）;（4） Ganshu（BL 18）, Zusanli（ST 36）, Shenmen（HT 7）, Taichong（LR 3） and Baihui（GV 20）. The analysis of association pattern elaborated that Shenshu（BL 23） and Sanyinjiao（SP 6） won the highest support rate in the paired groups; Ganshu（BL 18）, Shenshu（BL 23） and Sanyinjiao（SP 6） had the highest support rate among the acupoint groups. Conclusion： The data mining results of acupuncture-moxibustion treatment of PMS substantially conform to the general principle in traditional acupuncture-moxibustion theories, able to reflect the acupoints selection and grouping pattern and provide references for acupuncture-moxibustion treatment of PMS.
基金sponsored by the National Natural Science Foundation of China (61625502, 11961141010, 61975176, and U19A2054)the Top-Notch Young Talents Program of China+1 种基金the Fundamental Research Funds for the Central Universitiessponsored by Singapore Ministry of Education under Grant Nos. MOE2018-T2-1-022 (S), MOE2015-T2-1-070, MOE2016-T3-1-006, and Tier 1 RG174/16 (S)
文摘Recent advances in non-radiative wireless power transfer(WPT)technique essentially relying on magnetic resonance and near-field coupling have successfully enabled a wide range of applications.However,WPT systems based on double resonators are severely limited to short-or mid-range distance,due to the deteriorating efficiency and power with long transfer distance.WPT systems based on multi-relay resonators can overcome this problem,which,however,suffer from sensitivity to perturbations and fabrication imperfections.Here,we experimentally demonstrate a concept of topological wireless power transfer(TWPT),where energy is transferred efficiently via the near-field coupling between two topological edge states localized at the ends of a one-dimensional radiowave topological insulator.Such a TWPT system can be modelled as a parity-time-symmetric Su-Schrieffer-Heeger(SSH)chain with complex boundary potentials.Besides,the coil configurations are judiciously designed,which significantly suppress the unwanted cross-couplings between nonadjacent coils that could break the chiral symmetry of the SSH chain.By tuning the inter-and intra-cell coupling strengths,we theoretically and experimentally demonstrate high energy transfer efficiency near the exceptional point of the topological edge states,even in the presence of disorder.The combination of topological metamaterials,non-Hermitian physics,and WPT techniques could promise a variety of robust,efficient WPT applications over long distances in electronics,transportation,and industry.
