Terminal ballistic tests using 7.62 mm armor-piercing incendiary (API) projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr (Ti-55531) alloy. The dynamic properties were de...Terminal ballistic tests using 7.62 mm armor-piercing incendiary (API) projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr (Ti-55531) alloy. The dynamic properties were determined by a split Hopkinson pressure bar (SHPB) test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.展开更多
Partially-depleted silicon-on-insulator(PDSOI)floating-body(FB)nMOSFETs and H-gate type body-contacted(BC)nMOSFETs are fabricated with different back channel implantation dosages. The off-state breakdown charact...Partially-depleted silicon-on-insulator(PDSOI)floating-body(FB)nMOSFETs and H-gate type body-contacted(BC)nMOSFETs are fabricated with different back channel implantation dosages. The off-state breakdown characteristics of these devices are presented. The off-state breakdown voltages of the FB nMOSFETs increase from 5.2 to 6. 7V, and those of the H-gate type BC nMOSFETs decrease from 11.9 to 9V as the back channel implantation dosages increase from 1.0 ×10^13 to 1.3×10^13 cm^-2. By measuring the parasitic bipolar transistor static gain and the breakdown characteristics of the pn junction between the drain and the body, the differences between the breakdown mechanisms of the FB and H-gate type BC nMOSFETs are analyzed and explained qualitatively.展开更多
Preparation of a high flux of hydrogen molecules in a specific vibrationally excited state is the major prerequisite and challenge in scattering experiments that use vibrationally excited hydrogen molecules as the tar...Preparation of a high flux of hydrogen molecules in a specific vibrationally excited state is the major prerequisite and challenge in scattering experiments that use vibrationally excited hydrogen molecules as the target. The widely used scheme of stimulated Raman pumping suffers from coherent population return which severely limits the excitation efficiency. Re- cently we successfully transferred D2 molecules in the molecular beam from (v=0, J=0) to (v=1, J=0) level, with the scheme of Stark-induced adiabatic Raman passage. As high as 75% of the excitation efficiency was achieved. This excitation technique promise to be a unique tool for crossed beam and beam-surface scattering experiments which aim to reveal the role of vibrational excitation of hydrogen molecules in the chemical reaction.展开更多
The heat How generated from the infinite rock mass surrounding the underground tunnels is a major cause for the increasing cooling demands in deep mine tunnels.Insulation layers with lower thermal conductivities on tu...The heat How generated from the infinite rock mass surrounding the underground tunnels is a major cause for the increasing cooling demands in deep mine tunnels.Insulation layers with lower thermal conductivities on tunnel walls and roof ceilings are believed to supply a thermo-barrier for heat abatement.However,it is found that no systematic theoretical investigations were made to predict and confirm the effectiveness of underground thermal insulation.Specifically,investigations on the underground insulation problems involving heat flows through the semi-infinite hot rock mass and insulation layer were not sufficient.Thus,in this paper,the thermal characteristics,accompanied with heat flow through the semi-infinite rock mass and the insulation layer,were modeled by both analytical and numerical methods with focus on underground mine tunnels.The close agreements between models have indicated that the thermal insulation applied on tunnel surfaces is able to provide promising heat abatement effects.展开更多
We propose a scheme to produce quantum phase gates for trapped ions. Taking advantage of the adiabatic evolution, the operation is insensitive to small fluctuations of experimental parameters. Furthermore, the sponta...We propose a scheme to produce quantum phase gates for trapped ions. Taking advantage of the adiabatic evolution, the operation is insensitive to small fluctuations of experimental parameters. Furthermore, the spontaneous emission is suppressed since the ions have no probability of being populated in the electronic excited states.展开更多
A scheme is proposed to generate W state of N atoms trapped in a cavity,based on adiabatic passage alongdark state.Taking advantage of adiabatic passage,the atoms have no probability of being excited and thus the atom...A scheme is proposed to generate W state of N atoms trapped in a cavity,based on adiabatic passage alongdark state.Taking advantage of adiabatic passage,the atoms have no probability of being excited and thus the atomicspontaneous emission is suppressed.The scheme is simple.It does not need to adjust the interaction time accurately,anddoes not need to prepare the cavity field in one-photon state.Numerical simulation shows that the successful probabilityof the scheme increases with the increasing of the atom number.展开更多
Recently, Zhou et al. [Phys. Rev. A 79 (2009) 044304] proposed a scheme for transferring three-dimensional quantum states between remote atomic qubits confined in cavities connected by fibers through adiabatic passa...Recently, Zhou et al. [Phys. Rev. A 79 (2009) 044304] proposed a scheme for transferring three-dimensional quantum states between remote atomic qubits confined in cavities connected by fibers through adiabatic passage. In order to avoid the decoherence due to spontaneous emission, Zhou et al. utilized the large detuning atom-field interaction. In the present paper, we discuss the influence of dissipation on the scheme in both the resonant atom-field interaction case and the large detuning case. We numerically analyze the success probability and the transferring fidelity. It is shown that the resonant case is a preferable choice for the technique of the stimulated Raman adiabatic passage (STIRAP) due to the shorter operation time and the smaller probability of dissipation.展开更多
A scheme is proposed to generate W state with qubits of superconducting quantum interference devices (SQUIDs), based on adiabatic passage along dark state. Taking advantages of adiabatic passage, the scheme is very ...A scheme is proposed to generate W state with qubits of superconducting quantum interference devices (SQUIDs), based on adiabatic passage along dark state. Taking advantages of adiabatic passage, the scheme is very robust against decoherence, and it does not need to control the classical field and the interaction time accurately. Because of the achievable strong coupling between SQUID qubits and cavity, W state can be generated with high successful probability.展开更多
We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating thecluster states with rf superconducting quantum interference devices (SQUIDs)coupled to a microwave cavity throug...We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating thecluster states with rf superconducting quantum interference devices (SQUIDs)coupled to a microwave cavity throughadiabatic evolution of dark eigenstates.During the operation,the spontaneous emission is suppressed since the rf SQUIDsare always in the three lowest flux states.Considering the influence from the cavity decay with achievable experimentalparameters,we numerically analyze the success probability and the fidelity for generating the two-SQUID maximallyentangled state and the controlled phase-shift gate by adiabatic passage.展开更多
We propose a scheme for realizing a controlled geometric phase gate for two neutral atoms.We apply thestimulated Raman adiabatic passage to transfer atoms from their ground states into Rydberg excited states, and use ...We propose a scheme for realizing a controlled geometric phase gate for two neutral atoms.We apply thestimulated Raman adiabatic passage to transfer atoms from their ground states into Rydberg excited states, and use theRydberg interaction induced energy shifts to generate geometric phase and construct quantum gates.展开更多
We have studied the quasiparticle transport in quantum-wire /ferromagnetic-insulator/d wave super- conductor Junction (q/FI/d) in the framework of the Blonder-Tinkham-Klapwijk model. We calculate the tunneling condu...We have studied the quasiparticle transport in quantum-wire /ferromagnetic-insulator/d wave super- conductor Junction (q/FI/d) in the framework of the Blonder-Tinkham-Klapwijk model. We calculate the tunneling conductance in q/FI/d as a function of the bias voltage at zero temperature and finite temperature based on Bogoliubov- de Gennes equations. Different from the case in normal-metal/insulator/d wave superconductor Junctions, the zero-bias conductance peaks vanish for the single-mode case. The tunneling conductance spectra depend on the magnitude of the exchange interaction at the ferromagnetic-insulator.展开更多
We present a comprehensive view and details of calculations on Aharonov-Anandan phase for the charged particles in the external electric and magnetic fields for a nonadiabatic process.We derive,with consideration of a...We present a comprehensive view and details of calculations on Aharonov-Anandan phase for the charged particles in the external electric and magnetic fields for a nonadiabatic process.We derive,with consideration of a spin-orbit interaction and Zeemann Splitting,the persistent currents as a response to an Aharonov-Casher topological interference effect in one-dimensional mesoscopic ring.We also establish a connection to Berry adiabatic phase with deduced dynamical-nature dependence in the nonadiabatic process.The second quantization representation has also been employed in exhibition of persistent currents in the many-body case.展开更多
We investigated the vibration of a cleaning robot for hotline insulators, providing a flexible elevating link with a rigid moving link at the end. A Lagrange dynamic model is established based on the assumed mode meth...We investigated the vibration of a cleaning robot for hotline insulators, providing a flexible elevating link with a rigid moving link at the end. A Lagrange dynamic model is established based on the assumed mode method. An approach is proposed to reduce residual vibration of the flexible elevating link by optimizing acceleration of rigid link using the Pontryagin maximum principle (PMP). A numerical solution to the proposed optimization problem including a two-point boundary-value problem (2PBVP) is developed. Residual vibration of the flexible elevating link of the optimal acceleration profile is compared with that of the optimal trapezoid velocity profile. The result shows that the proposed trajectory optimization method can reduce the residual vibration more effectively.展开更多
We propose a deterministic quantum secure direct two check photon sequences are used to check the securities of the communication protocol by using dense coding. The channels between the message sender and the receive...We propose a deterministic quantum secure direct two check photon sequences are used to check the securities of the communication protocol by using dense coding. The channels between the message sender and the receiver. The continuous variable operations instead of the usual discrete unitary operations are performed on the travel photons so that the security of the present protocol can be enhanced. Therefore some specific attacks such as denial-of-service attack, intercept-measure-resend attack and invisible photon attack can be prevented in ideal quantum channel. In addition, the scheme is still secure in noise channel. Furthurmore, this protocol has the advantage of high capacity and can be realized in the experiment.展开更多
The Bogoliubov de Gennes equation is applied to the study of coherence effects in the ferromagnetic superconductor/insulator/normal metal/insulator/ferromagnetic/superconductor (FS/I/N/I/FS) junction. We calculated ...The Bogoliubov de Gennes equation is applied to the study of coherence effects in the ferromagnetic superconductor/insulator/normal metal/insulator/ferromagnetic/superconductor (FS/I/N/I/FS) junction. We calculated the Josephson current in FS/I/N/I/FS as a function of exchange field in ferromagnetic superconductor, temperature, and normal metal thickness. It is found that the Josephson critical current in FS/I/N/I/FS exhibits oscillations as a function of the length of normal metal. The exchange field always suppresses the Josephson critical current Ip for a parallel configuration of the magnetic moments of two ferromagnetic superconductor (FS) electrodes. In the antiparallel configuration, the Josephson critical current IAv at the minimum values of oscillation increases with the exchange field for strong barrier strength and at low temperatures.展开更多
The corrosion under insulation dominates metal loss in the case of API (American Petroleum Institute) 5L Grade B geothermal pipeline, whereas, the other possible corrosion causes, such as stress corrosion and therma...The corrosion under insulation dominates metal loss in the case of API (American Petroleum Institute) 5L Grade B geothermal pipeline, whereas, the other possible corrosion causes, such as stress corrosion and thermal cracking, did not serve a role as critical factors regarding to pipeline degradation during 26-years working operation. Actually, the header pipe diameter 32 inches and 40 inches require priority for inspection due to higher corrosion rate compared to smaller pipe diameters. By simulation method on similar heavy duty service condition in which the working pressure of 15 bars and temperature of 183 ℃, it was proved that corrosion rate will severely occur at corrosion rate more than 10 mpy in the pipe diameters of 20 inches, 32 inches and 40 inches. Further,condensation factor may contribute more significant in the case of corrosion under insulation. Practically, the metal loss at a half initial thickness requires priority for inspection, intensive maintenance or possible partial replacement.展开更多
基金Project(2012 DFG51540)supported by the Ministry of Science and Technology of China
文摘Terminal ballistic tests using 7.62 mm armor-piercing incendiary (API) projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr (Ti-55531) alloy. The dynamic properties were determined by a split Hopkinson pressure bar (SHPB) test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.
文摘Partially-depleted silicon-on-insulator(PDSOI)floating-body(FB)nMOSFETs and H-gate type body-contacted(BC)nMOSFETs are fabricated with different back channel implantation dosages. The off-state breakdown characteristics of these devices are presented. The off-state breakdown voltages of the FB nMOSFETs increase from 5.2 to 6. 7V, and those of the H-gate type BC nMOSFETs decrease from 11.9 to 9V as the back channel implantation dosages increase from 1.0 ×10^13 to 1.3×10^13 cm^-2. By measuring the parasitic bipolar transistor static gain and the breakdown characteristics of the pn junction between the drain and the body, the differences between the breakdown mechanisms of the FB and H-gate type BC nMOSFETs are analyzed and explained qualitatively.
文摘Preparation of a high flux of hydrogen molecules in a specific vibrationally excited state is the major prerequisite and challenge in scattering experiments that use vibrationally excited hydrogen molecules as the target. The widely used scheme of stimulated Raman pumping suffers from coherent population return which severely limits the excitation efficiency. Re- cently we successfully transferred D2 molecules in the molecular beam from (v=0, J=0) to (v=1, J=0) level, with the scheme of Stark-induced adiabatic Raman passage. As high as 75% of the excitation efficiency was achieved. This excitation technique promise to be a unique tool for crossed beam and beam-surface scattering experiments which aim to reveal the role of vibrational excitation of hydrogen molecules in the chemical reaction.
基金The financial support from an Engage Grant in the Natural Sciences and Engineering Research Council(NSERC),Canada,is gratefully acknowledged
文摘The heat How generated from the infinite rock mass surrounding the underground tunnels is a major cause for the increasing cooling demands in deep mine tunnels.Insulation layers with lower thermal conductivities on tunnel walls and roof ceilings are believed to supply a thermo-barrier for heat abatement.However,it is found that no systematic theoretical investigations were made to predict and confirm the effectiveness of underground thermal insulation.Specifically,investigations on the underground insulation problems involving heat flows through the semi-infinite hot rock mass and insulation layer were not sufficient.Thus,in this paper,the thermal characteristics,accompanied with heat flow through the semi-infinite rock mass and the insulation layer,were modeled by both analytical and numerical methods with focus on underground mine tunnels.The close agreements between models have indicated that the thermal insulation applied on tunnel surfaces is able to provide promising heat abatement effects.
基金The project supported by National Natural Science Foundation of China under Grant No. 10674025 and the Funds from Fuzhou University
文摘We propose a scheme to produce quantum phase gates for trapped ions. Taking advantage of the adiabatic evolution, the operation is insensitive to small fluctuations of experimental parameters. Furthermore, the spontaneous emission is suppressed since the ions have no probability of being populated in the electronic excited states.
基金Supported by the Science Foundation of Educational Committee of Fujian Province under Grant No.JB09011
文摘A scheme is proposed to generate W state of N atoms trapped in a cavity,based on adiabatic passage alongdark state.Taking advantage of adiabatic passage,the atoms have no probability of being excited and thus the atomicspontaneous emission is suppressed.The scheme is simple.It does not need to adjust the interaction time accurately,anddoes not need to prepare the cavity field in one-photon state.Numerical simulation shows that the successful probabilityof the scheme increases with the increasing of the atom number.
文摘Recently, Zhou et al. [Phys. Rev. A 79 (2009) 044304] proposed a scheme for transferring three-dimensional quantum states between remote atomic qubits confined in cavities connected by fibers through adiabatic passage. In order to avoid the decoherence due to spontaneous emission, Zhou et al. utilized the large detuning atom-field interaction. In the present paper, we discuss the influence of dissipation on the scheme in both the resonant atom-field interaction case and the large detuning case. We numerically analyze the success probability and the transferring fidelity. It is shown that the resonant case is a preferable choice for the technique of the stimulated Raman adiabatic passage (STIRAP) due to the shorter operation time and the smaller probability of dissipation.
基金Supported by the Foundation of Educational Committee of Fujian Province under Grant Nos.JB09012 and JB09013
文摘A scheme is proposed to generate W state with qubits of superconducting quantum interference devices (SQUIDs), based on adiabatic passage along dark state. Taking advantages of adiabatic passage, the scheme is very robust against decoherence, and it does not need to control the classical field and the interaction time accurately. Because of the achievable strong coupling between SQUID qubits and cavity, W state can be generated with high successful probability.
文摘We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating thecluster states with rf superconducting quantum interference devices (SQUIDs)coupled to a microwave cavity throughadiabatic evolution of dark eigenstates.During the operation,the spontaneous emission is suppressed since the rf SQUIDsare always in the three lowest flux states.Considering the influence from the cavity decay with achievable experimentalparameters,we numerically analyze the success probability and the fidelity for generating the two-SQUID maximallyentangled state and the controlled phase-shift gate by adiabatic passage.
基金Supported by the National Natural Science Foundation of China under Grant No.10974028 the Doctoral Foundation of the Ministry of Education of China under Grant No.20093514110009+1 种基金 the Natural Science Foundation of Fujian Province under Grant No.2009J06002Funds from the State Key Laboratory Breeding Base of Photocatalysis,Fuzhou University
文摘We propose a scheme for realizing a controlled geometric phase gate for two neutral atoms.We apply thestimulated Raman adiabatic passage to transfer atoms from their ground states into Rydberg excited states, and use theRydberg interaction induced energy shifts to generate geometric phase and construct quantum gates.
基金The project supported by the Natural Science Foundation of the Education Committee of Jiangsu Province of China under Grant No.06KJB140009
文摘We have studied the quasiparticle transport in quantum-wire /ferromagnetic-insulator/d wave super- conductor Junction (q/FI/d) in the framework of the Blonder-Tinkham-Klapwijk model. We calculate the tunneling conductance in q/FI/d as a function of the bias voltage at zero temperature and finite temperature based on Bogoliubov- de Gennes equations. Different from the case in normal-metal/insulator/d wave superconductor Junctions, the zero-bias conductance peaks vanish for the single-mode case. The tunneling conductance spectra depend on the magnitude of the exchange interaction at the ferromagnetic-insulator.
基金The project supported by National Natural Science Foundation of China under Grant Nos.90103077 and 10274069Natural Science Foundation of Guangdong Province of China under Grant No.011151
文摘We present a comprehensive view and details of calculations on Aharonov-Anandan phase for the charged particles in the external electric and magnetic fields for a nonadiabatic process.We derive,with consideration of a spin-orbit interaction and Zeemann Splitting,the persistent currents as a response to an Aharonov-Casher topological interference effect in one-dimensional mesoscopic ring.We also establish a connection to Berry adiabatic phase with deduced dynamical-nature dependence in the nonadiabatic process.The second quantization representation has also been employed in exhibition of persistent currents in the many-body case.
文摘We investigated the vibration of a cleaning robot for hotline insulators, providing a flexible elevating link with a rigid moving link at the end. A Lagrange dynamic model is established based on the assumed mode method. An approach is proposed to reduce residual vibration of the flexible elevating link by optimizing acceleration of rigid link using the Pontryagin maximum principle (PMP). A numerical solution to the proposed optimization problem including a two-point boundary-value problem (2PBVP) is developed. Residual vibration of the flexible elevating link of the optimal acceleration profile is compared with that of the optimal trapezoid velocity profile. The result shows that the proposed trajectory optimization method can reduce the residual vibration more effectively.
基金supported by the Natural Science Research Programme of the Education Department of Anhui Province under Grant No. KJ2009B039Zthe Municipal Level Research Project from Lu'an City directive entrusted to West Anhui University under Grant No. 2008lw004
文摘We propose a deterministic quantum secure direct two check photon sequences are used to check the securities of the communication protocol by using dense coding. The channels between the message sender and the receiver. The continuous variable operations instead of the usual discrete unitary operations are performed on the travel photons so that the security of the present protocol can be enhanced. Therefore some specific attacks such as denial-of-service attack, intercept-measure-resend attack and invisible photon attack can be prevented in ideal quantum channel. In addition, the scheme is still secure in noise channel. Furthurmore, this protocol has the advantage of high capacity and can be realized in the experiment.
基金Supported by the Natural Science Foundation of Jiangsu Higher Education Institutions of China under Grant No.06KJB140009
文摘The Bogoliubov de Gennes equation is applied to the study of coherence effects in the ferromagnetic superconductor/insulator/normal metal/insulator/ferromagnetic/superconductor (FS/I/N/I/FS) junction. We calculated the Josephson current in FS/I/N/I/FS as a function of exchange field in ferromagnetic superconductor, temperature, and normal metal thickness. It is found that the Josephson critical current in FS/I/N/I/FS exhibits oscillations as a function of the length of normal metal. The exchange field always suppresses the Josephson critical current Ip for a parallel configuration of the magnetic moments of two ferromagnetic superconductor (FS) electrodes. In the antiparallel configuration, the Josephson critical current IAv at the minimum values of oscillation increases with the exchange field for strong barrier strength and at low temperatures.
文摘The corrosion under insulation dominates metal loss in the case of API (American Petroleum Institute) 5L Grade B geothermal pipeline, whereas, the other possible corrosion causes, such as stress corrosion and thermal cracking, did not serve a role as critical factors regarding to pipeline degradation during 26-years working operation. Actually, the header pipe diameter 32 inches and 40 inches require priority for inspection due to higher corrosion rate compared to smaller pipe diameters. By simulation method on similar heavy duty service condition in which the working pressure of 15 bars and temperature of 183 ℃, it was proved that corrosion rate will severely occur at corrosion rate more than 10 mpy in the pipe diameters of 20 inches, 32 inches and 40 inches. Further,condensation factor may contribute more significant in the case of corrosion under insulation. Practically, the metal loss at a half initial thickness requires priority for inspection, intensive maintenance or possible partial replacement.