The interdendritic segregation along the mushy zone of directionally solidified superalloy Inconel 718 has been measured by scanning electron microscope (SEM) and energy dispersion analysis spectrometry (EDAX) techniq...The interdendritic segregation along the mushy zone of directionally solidified superalloy Inconel 718 has been measured by scanning electron microscope (SEM) and energy dispersion analysis spectrometry (EDAX) techniques and the corresponding liquid composition profile was presented. The liquid density and Rayleigh number (Ra) pro files along the mushy zone were calculated as well. It was found that the liquid density difference increased from top to bottom in the mushy zone and there was no density inversion due to the segregation of Nb and Mo. However carbide formation in the freezing range and the preferred angle of the orientated dendrite array could prompt the fluid flow in the mushy zone although there was no liquid density inversion. The largest relative Rayleigh number appeared at 1,326 °C for Inconel 718 where the fluid flow most easily occurred.展开更多
Samples of surface chromising layer were prepared by the double glow plasma discharge technique. X-ray diffraction and X-ray photoelectron spectroscopy(XPS) analysis of dif-ferent elements confirmed the formation of c...Samples of surface chromising layer were prepared by the double glow plasma discharge technique. X-ray diffraction and X-ray photoelectron spectroscopy(XPS) analysis of dif-ferent elements confirmed the formation of chrome in the layer. Their tribological properties were investigated by pin-on-disk tribometer. Silicon nitride, GCr15, and nickel-based alloy were selected as counterface materials. Results indicated that the lowest friction coefficients and wear rate were ob-tained when substrate and chromising layer against nickel-based alloy, and tribological properties of chromising layer were better than those of substrate. The highest friction and wear rate were samples against silicon nitride alloys. In the case of three rubbing pairs, the unchangeable materials against different hardness counterfaces leaded to different wear mechanisms. Samples against silicon nitride exhibited abrasive mechanism, and when GCr15 and nickel-based alloy were used as counterface, transfer film and glaze layer formed on the contact surface, which played the main role in decreasing friction and wear.展开更多
Plasma tungstening followed by carburization(W-C duplex treatment)was performed on the Ti2AlNb-based(O phase) alloy by using the double glow plasma process to enhance its wear resistance.The microstructure and high-te...Plasma tungstening followed by carburization(W-C duplex treatment)was performed on the Ti2AlNb-based(O phase) alloy by using the double glow plasma process to enhance its wear resistance.The microstructure and high-temperature tribological behaviors of the un-treated and W-C duplex-treated samples were investigated.The results show that the duplex-treated layer is mainly composed of W2C or W6C2.54 phases and the contents of W and C elements in the alloyed layer change gradually along the depth by surface plasma duplex treatment.The diffusion depth of W is about 12μm,while the carbon atoms most exist in the depth more than 12μm.High temperature tribometer tests indicate that the friction coefficient of the W-C duplex-treated layer is approximately 1/6 that of substrate.The wear rate of the duplex-treated layer is about 28%that of the untreated one.So,plasma surface W-C duplex treatment can obviously improve the high-temperature tribological resistance of Ti2AlNb-based alloy.The tribological mechanism of the duplex-treated layer is discussed by dividing the friction process of the duplex-treated layer into three fluctuate stages.The first stage is the formation of oxide film between W-C duplex-treated layer and counterface.The second stage is the detachment of oxide film,acting as "the third body" .The last stage is the period that the friction and wear occur between the compact particle layer and counterface.展开更多
Ni-Cr alloyed layer was formed on surface of Q235 steel by double glow plasma surface metallurgy to improve the corrosion resistance of substrate. The composition and microstructure of alloyed layer was analyzed by SE...Ni-Cr alloyed layer was formed on surface of Q235 steel by double glow plasma surface metallurgy to improve the corrosion resistance of substrate. The composition and microstructure of alloyed layer was analyzed by SEM and XRD. Potentiodynamic polarization and electrochemical impedance spectroscopy was applied to evaluate the corrosion resistance of the alloyed layer. The results showed working pressure had a great effect on structure of Ni-Cr alloyed layer, and the dense and smooth alloyed layer was prepared at 50 Pa working pressure. Compared with substrate, Ni-Cr alloyed layer exhibited higher corrosion potential, lower corrosion current density and larger charge transfer resistance, which indicated that Ni-Cr alloyed layer significantly modified the corrosion resistance of Q235 steel.展开更多
The researches on the structure of water and its changes induced by solutes are of enduring interests.The changes of the local structure of liquid water induced by NaCl solute under ambient conditions are studied and ...The researches on the structure of water and its changes induced by solutes are of enduring interests.The changes of the local structure of liquid water induced by NaCl solute under ambient conditions are studied and presented quantitatively with some order parameters and visualized with 2-body and 3-body correlation functions.The results show that,after the NaCl are solvated,the translational order t of water is decreased for the suppression of the second hydration shells around H 2 O molecules;the tetrahedral order q of water is also decreased and its favorite distribution peak moves from 0.76 to 0.5.In addition,the orientational freedom k and the diffusion coefficient D of water molecules are reduced because of new formed hydrogen-bonding structures between water and solvated ions.展开更多
Based on the main physical processes,we deduce the relationships among the incident energy Wp0 of the primary electron,the number of released secondary electrons(i.e.δ_(PEθ))per primary electron entering the metal a...Based on the main physical processes,we deduce the relationships among the incident energy Wp0 of the primary electron,the number of released secondary electrons(i.e.δ_(PEθ))per primary electron entering the metal at incident angleθand the angleθitself.In addition,the relationship ofδPEθatθ=0°,i.e.δ_(PE0),with Wp0 is determined.From the experimental results,the relationship of the ratio atθ=0°,i.e.β_(0) which is the ratio of the average number of released secondary electrons generated by a single primary electron backscattered at the metal surface to that generated by a single primary electron entering the metal,with Wp0 is determined.Moreover,the relationships among the ratioβθ,Wp0 andθare obtained.Based on the relationships among the secondary electron yield atθ(i.e.δθ),the yield atθ=0°(i.e.δ_(0)),the backscattering coefficient atθ(i.e.η_(θ)),the coefficient atθ=0°(i.e.η0),δ_(PEθ)andδ_(PE0),we deduce the universal formula forδ_(θ),δ_(0),η_(θ),η_(0),and W_(p0) for the primary electrons at an incident energy of 2–10 keV.The secondary electron yields calculated from the universal formula and the experimental yields of some metals are compared,and the results suggest that the proposed formula is universal for estimation of secondary electron yields atθ=0°−80°.展开更多
We propose a bidirectional quantum secure direct communication(QSDC) network protocol with the hyperentanglment in both the spatial-mode ad the polarization degrees of freedom of photon pairs which can in principle be...We propose a bidirectional quantum secure direct communication(QSDC) network protocol with the hyperentanglment in both the spatial-mode ad the polarization degrees of freedom of photon pairs which can in principle be produced with a beta barium borate crystal.The secret message can be encoded on the photon pairs with unitary operations in these two degrees of freedom independently.Compared with other QSDC network protocols,our QSDC network protocol has a higher capacity as each photon pair can carry 4 bits of information.Also,we discuss the security of our QSDC network protocol and its feasibility with current techniques.展开更多
This paper presents a scheme for high-capacity three-party quantum secret sharing with quantum superdense coding,following some ideas in the work by Liu et al (2002 Phys.Rev.A 65 022304) and the quantum secret sharing...This paper presents a scheme for high-capacity three-party quantum secret sharing with quantum superdense coding,following some ideas in the work by Liu et al (2002 Phys.Rev.A 65 022304) and the quantum secret sharing scheme by Deng et al (2008 Phys.Lett.A 372 1957).Instead of using two sets of nonorthogonal states,the boss Alice needs only to prepare a sequence of Einstein–Podolsky–Rosen pairs in d-dimension.The two agents Bob and Charlie encode their information with dense coding unitary operations,and security is checked by inserting decoy photons.The scheme has a high capacity and intrinsic efficiency as each pair can carry 2lbd bits of information,and almost all the pairs can be used for carrying useful information.展开更多
We present a scheme for multiparty quantum remote secret conference (MQRSC) with pure entangled states, not maximally entangled multipartite quantum systems. The conferees first share a private quantum key,a sequence ...We present a scheme for multiparty quantum remote secret conference (MQRSC) with pure entangled states, not maximally entangled multipartite quantum systems. The conferees first share a private quantum key,a sequence of pure entangled states and then use them to encode and decode the secret messages. The conferees exploit the decoy-photon technique to ensure the security of the transmission of qubits. This MQRSC scheme is more feasible and effcient than others.展开更多
The glass-forming ability and the thermal stabilityof Cu45Zr45Al5Ni5 metallic glass were systematically investigated by the differential scanning calorimetry.The activation energies for the glass transition and the on...The glass-forming ability and the thermal stabilityof Cu45Zr45Al5Ni5 metallic glass were systematically investigated by the differential scanning calorimetry.The activation energies for the glass transition and the onset crystallization and the crystallization peak were calculated to be 255.1,308.7 and 311.5 kJ/mol,respectively,while the corresponding liquid fragility was determined to be 23.4.By controlling the casting process,Cu45Zr45Al5Ni5 bulk metallic glass composite with the presence of ductile B2 CuZr phase was fabricated.The composite shows a pronounced plastic strain of 6.8 0.05% with obvious work hardening,which results from the formation of multiple shear bands and the deformation-induced martensitic transformation.展开更多
The asymptotic behaviour of solutions for general partly dissipative reaction-diffusion systems in Rn is studied. The asymptotic compactness of the solutions and then the existence of the global attractor are proved i...The asymptotic behaviour of solutions for general partly dissipative reaction-diffusion systems in Rn is studied. The asymptotic compactness of the solutions and then the existence of the global attractor are proved in L2(Rn )× L2(Rn ) .展开更多
We present two deterministic secure quantum communication schemes over a collective-noise. One is used to complete the secure quantum communication against a collective-rotation noise and the other is used against a c...We present two deterministic secure quantum communication schemes over a collective-noise. One is used to complete the secure quantum communication against a collective-rotation noise and the other is used against a collective-dephasing noise. The two parties of quantum communication can exploit the correlation of their subsystems to check eavesdropping efficiently. Although the sender should prepare a sequence of three-photon entangled states for accomplishing secure communication against a collective noise,the two parties need only single-photon measurements,rather than Bell-state measurements,which will make our schemes convenient in practical application.展开更多
We present two robust quantum secure direct communication (QSDC) schemes with a quantum one-time pad over a collective-noise channel. Each logical qubit is made up of two physical qubits and it is invariant over a col...We present two robust quantum secure direct communication (QSDC) schemes with a quantum one-time pad over a collective-noise channel. Each logical qubit is made up of two physical qubits and it is invariant over a collective-noise channel. The two photons in each logical qubit can be produced with a practically entangled source, i.e., a parametric down-conversion source with a beta barium borate crystal and a pump pulse of ultraviolet light. The information is encoded on each logical qubit with two logical unitary operations, which will not destroy the antinoise feather of the quantum systems. The receiver Bob can read out the sender's message directly with two single-photon measurements on each logical qubit, instead of Bell-state measurements, which will make these protocols more convenient in a practical application. With current technology, our two robust QSDC schemes are feasible and may be optimal ones.展开更多
基金supported by the National Natural Science Foundation of China (No. 50371006)the school fund of Nanjing University of Information Science and Technology
文摘The interdendritic segregation along the mushy zone of directionally solidified superalloy Inconel 718 has been measured by scanning electron microscope (SEM) and energy dispersion analysis spectrometry (EDAX) techniques and the corresponding liquid composition profile was presented. The liquid density and Rayleigh number (Ra) pro files along the mushy zone were calculated as well. It was found that the liquid density difference increased from top to bottom in the mushy zone and there was no density inversion due to the segregation of Nb and Mo. However carbide formation in the freezing range and the preferred angle of the orientated dendrite array could prompt the fluid flow in the mushy zone although there was no liquid density inversion. The largest relative Rayleigh number appeared at 1,326 °C for Inconel 718 where the fluid flow most easily occurred.
基金Funded by the Natural Science Foundation of Jiangsu Province China(No.BK2005128)the Scientific Research Foundation of Nanjing University of Information and Technology
文摘Samples of surface chromising layer were prepared by the double glow plasma discharge technique. X-ray diffraction and X-ray photoelectron spectroscopy(XPS) analysis of dif-ferent elements confirmed the formation of chrome in the layer. Their tribological properties were investigated by pin-on-disk tribometer. Silicon nitride, GCr15, and nickel-based alloy were selected as counterface materials. Results indicated that the lowest friction coefficients and wear rate were ob-tained when substrate and chromising layer against nickel-based alloy, and tribological properties of chromising layer were better than those of substrate. The highest friction and wear rate were samples against silicon nitride alloys. In the case of three rubbing pairs, the unchangeable materials against different hardness counterfaces leaded to different wear mechanisms. Samples against silicon nitride exhibited abrasive mechanism, and when GCr15 and nickel-based alloy were used as counterface, transfer film and glaze layer formed on the contact surface, which played the main role in decreasing friction and wear.
基金Project supported by the Scientific Research Foundation of Nanjing University of Information and Technology,China
文摘Plasma tungstening followed by carburization(W-C duplex treatment)was performed on the Ti2AlNb-based(O phase) alloy by using the double glow plasma process to enhance its wear resistance.The microstructure and high-temperature tribological behaviors of the un-treated and W-C duplex-treated samples were investigated.The results show that the duplex-treated layer is mainly composed of W2C or W6C2.54 phases and the contents of W and C elements in the alloyed layer change gradually along the depth by surface plasma duplex treatment.The diffusion depth of W is about 12μm,while the carbon atoms most exist in the depth more than 12μm.High temperature tribometer tests indicate that the friction coefficient of the W-C duplex-treated layer is approximately 1/6 that of substrate.The wear rate of the duplex-treated layer is about 28%that of the untreated one.So,plasma surface W-C duplex treatment can obviously improve the high-temperature tribological resistance of Ti2AlNb-based alloy.The tribological mechanism of the duplex-treated layer is discussed by dividing the friction process of the duplex-treated layer into three fluctuate stages.The first stage is the formation of oxide film between W-C duplex-treated layer and counterface.The second stage is the detachment of oxide film,acting as "the third body" .The last stage is the period that the friction and wear occur between the compact particle layer and counterface.
基金the Jiangsu Province Technology Results Transformation Special Funds (No. BA2007036)
文摘Ni-Cr alloyed layer was formed on surface of Q235 steel by double glow plasma surface metallurgy to improve the corrosion resistance of substrate. The composition and microstructure of alloyed layer was analyzed by SEM and XRD. Potentiodynamic polarization and electrochemical impedance spectroscopy was applied to evaluate the corrosion resistance of the alloyed layer. The results showed working pressure had a great effect on structure of Ni-Cr alloyed layer, and the dense and smooth alloyed layer was prepared at 50 Pa working pressure. Compared with substrate, Ni-Cr alloyed layer exhibited higher corrosion potential, lower corrosion current density and larger charge transfer resistance, which indicated that Ni-Cr alloyed layer significantly modified the corrosion resistance of Q235 steel.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10847147)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 200800270017)the research foundation of NUIST (Grant No. 20080279)
文摘The researches on the structure of water and its changes induced by solutes are of enduring interests.The changes of the local structure of liquid water induced by NaCl solute under ambient conditions are studied and presented quantitatively with some order parameters and visualized with 2-body and 3-body correlation functions.The results show that,after the NaCl are solvated,the translational order t of water is decreased for the suppression of the second hydration shells around H 2 O molecules;the tetrahedral order q of water is also decreased and its favorite distribution peak moves from 0.76 to 0.5.In addition,the orientational freedom k and the diffusion coefficient D of water molecules are reduced because of new formed hydrogen-bonding structures between water and solvated ions.
基金by Scientific Research Fund of Nanjing University of Information Science and Technology(No S8108197001)the Natural Science Foundation of Jiangsu Provincial Universities(No 10KJB180004).
文摘Based on the main physical processes,we deduce the relationships among the incident energy Wp0 of the primary electron,the number of released secondary electrons(i.e.δ_(PEθ))per primary electron entering the metal at incident angleθand the angleθitself.In addition,the relationship ofδPEθatθ=0°,i.e.δ_(PE0),with Wp0 is determined.From the experimental results,the relationship of the ratio atθ=0°,i.e.β_(0) which is the ratio of the average number of released secondary electrons generated by a single primary electron backscattered at the metal surface to that generated by a single primary electron entering the metal,with Wp0 is determined.Moreover,the relationships among the ratioβθ,Wp0 andθare obtained.Based on the relationships among the secondary electron yield atθ(i.e.δθ),the yield atθ=0°(i.e.δ_(0)),the backscattering coefficient atθ(i.e.η_(θ)),the coefficient atθ=0°(i.e.η0),δ_(PEθ)andδ_(PE0),we deduce the universal formula forδ_(θ),δ_(0),η_(θ),η_(0),and W_(p0) for the primary electrons at an incident energy of 2–10 keV.The secondary electron yields calculated from the universal formula and the experimental yields of some metals are compared,and the results suggest that the proposed formula is universal for estimation of secondary electron yields atθ=0°−80°.
基金Supported by the Natural Science Foundation of Jiangsu Provincial Universities under Grant No.10KJB180004the National Natural Science Foundation of China under Grant No.11105075
文摘We propose a bidirectional quantum secure direct communication(QSDC) network protocol with the hyperentanglment in both the spatial-mode ad the polarization degrees of freedom of photon pairs which can in principle be produced with a beta barium borate crystal.The secret message can be encoded on the photon pairs with unitary operations in these two degrees of freedom independently.Compared with other QSDC network protocols,our QSDC network protocol has a higher capacity as each photon pair can carry 4 bits of information.Also,we discuss the security of our QSDC network protocol and its feasibility with current techniques.
基金Project supported by the National Natural Science Foundation (NSF) of China (Grant No 10847147)the NSF of Jiangsu Province, China (Grant No BK2008437)+1 种基金Jiangsu Provincial Universities (Grant No 07KJB510066)the Science Foundation of NUIST, China
文摘This paper presents a scheme for high-capacity three-party quantum secret sharing with quantum superdense coding,following some ideas in the work by Liu et al (2002 Phys.Rev.A 65 022304) and the quantum secret sharing scheme by Deng et al (2008 Phys.Lett.A 372 1957).Instead of using two sets of nonorthogonal states,the boss Alice needs only to prepare a sequence of Einstein–Podolsky–Rosen pairs in d-dimension.The two agents Bob and Charlie encode their information with dense coding unitary operations,and security is checked by inserting decoy photons.The scheme has a high capacity and intrinsic efficiency as each pair can carry 2lbd bits of information,and almost all the pairs can be used for carrying useful information.
基金Project supported by the National Natural Science Foundation of China (Grant No 10847147)the Natural Science Foundation of Jiangsu Province (Grant No BK2008437)+1 种基金Jiangsu Provincial Universities (Grant No 07KJB510066)the Science Foundation of Nanjing University of Information Science and Technology
文摘We present a scheme for multiparty quantum remote secret conference (MQRSC) with pure entangled states, not maximally entangled multipartite quantum systems. The conferees first share a private quantum key,a sequence of pure entangled states and then use them to encode and decode the secret messages. The conferees exploit the decoy-photon technique to ensure the security of the transmission of qubits. This MQRSC scheme is more feasible and effcient than others.
基金supported by the Chinese Scholarship Council (CSC)the Natural Science Foundation of Shandong Province (No. Z2008F08)+2 种基金the Excellent Youth Project of the Natural Science Foundation of Shandong Province (No. JQ201012)the National Basic Research Program of China (973 Program, No. 2007CB613901)the National Natural Science Foundation of China (Nos. 50631010 and 50831003)
文摘The glass-forming ability and the thermal stabilityof Cu45Zr45Al5Ni5 metallic glass were systematically investigated by the differential scanning calorimetry.The activation energies for the glass transition and the onset crystallization and the crystallization peak were calculated to be 255.1,308.7 and 311.5 kJ/mol,respectively,while the corresponding liquid fragility was determined to be 23.4.By controlling the casting process,Cu45Zr45Al5Ni5 bulk metallic glass composite with the presence of ductile B2 CuZr phase was fabricated.The composite shows a pronounced plastic strain of 6.8 0.05% with obvious work hardening,which results from the formation of multiple shear bands and the deformation-induced martensitic transformation.
文摘The asymptotic behaviour of solutions for general partly dissipative reaction-diffusion systems in Rn is studied. The asymptotic compactness of the solutions and then the existence of the global attractor are proved in L2(Rn )× L2(Rn ) .
基金supported by the National Key R&D Program of China(2020YFA0308800 and 2021YFA1400100)the National Natural Science Foundation of China(12074212)+7 种基金supported by the National Natural Science Foundation of China(12174214 and 92065205)the National Key R&D Program of China(2018YFA0306504)the Innovation Program for Quantum Science and Technology(2021ZD0302100)supported by the National Natural Science Foundation of China(12274252)the National Key R&D Program of China(2018YFA0307100)supported by the National Natural Science Foundation of China(21975140 and 51991343)Fundamental Research Funds for the Central Universities(Buctrc202212)supported by funds from the University of Toronto。
基金Supported by the National Natural Science Foundation of China (Grant No. 10847147)the Science Foundation of Nanjing University ofInformation Science & Technology (Grant No. 20080279)
文摘We present two deterministic secure quantum communication schemes over a collective-noise. One is used to complete the secure quantum communication against a collective-rotation noise and the other is used against a collective-dephasing noise. The two parties of quantum communication can exploit the correlation of their subsystems to check eavesdropping efficiently. Although the sender should prepare a sequence of three-photon entangled states for accomplishing secure communication against a collective noise,the two parties need only single-photon measurements,rather than Bell-state measurements,which will make our schemes convenient in practical application.
基金supported by the Natural Science Foundation of Jiangsu Provincial Universities (Grant No. 10KJB180004)the National Natural Science Foundation of China (Grant No. 10847147)
文摘We present two robust quantum secure direct communication (QSDC) schemes with a quantum one-time pad over a collective-noise channel. Each logical qubit is made up of two physical qubits and it is invariant over a collective-noise channel. The two photons in each logical qubit can be produced with a practically entangled source, i.e., a parametric down-conversion source with a beta barium borate crystal and a pump pulse of ultraviolet light. The information is encoded on each logical qubit with two logical unitary operations, which will not destroy the antinoise feather of the quantum systems. The receiver Bob can read out the sender's message directly with two single-photon measurements on each logical qubit, instead of Bell-state measurements, which will make these protocols more convenient in a practical application. With current technology, our two robust QSDC schemes are feasible and may be optimal ones.
