Mn-based intermetallic compounds have attracted much attention due to their fascinating structural and physical properties,especially their interesting hard magnetic properties.In this paper,we have summarized the mag...Mn-based intermetallic compounds have attracted much attention due to their fascinating structural and physical properties,especially their interesting hard magnetic properties.In this paper,we have summarized the magnetic and structural properties of Mn-based intermetallic compounds(Mn X,where X=Al,Bi,and Ga).Various methods for synthesizing single phases of MnAl,MnBi,and Mnx Ga were developed in our lab.A very high saturation magnetization of 125 emu/g,coercivity of 5 kOe,and maximum energy product(BH)_(max)of 3.1 MG·Oe were achieved at room temperature for the pureτ-Mn–Al magnetic phase without carbon doping and the extrusion process.Low temperature phase(LTP)MnBi with a purity above 95 wt.%can be synthesized.An abnormal temperature coefficient of the coercivity was observed for the LTP MnBi magnet.Its coercivity increased with temperature from 100 K to 540 K,reached a maximum of 2.5 T at about540 K,and then decreased slowly to 1.8 T at 610 K.The positive temperature coefficient of the coercivity is related to the evolution of the structure and magnetocrystalline anisotropy field of the LTP MnBi phase with temperature.The LTP MnBi bonded magnets show maximum energy products(BH)_(max)of 8.9 MG·Oe(70 kJ/m^(3))and 5.0 MG·Oe(40 k J/m^(3))at room temperature and 400 K,respectively.Ferrimagnetic Mn_(x)Ga phases with L10 structures(x〈2.0)and D0_(22)structures(x〉2.0)were obtained.All of the above structures can be described by a D0_(22)supercell model in which 2 a-Ga and 2 b-Mn are simultaneously substituted.The tetragonal D0_(22)phases of the Mn_(x)Ga show high coercivities ranging from 7.2 kOe for low Mn content x=1.8 to 18.2 kOe for high Mn content x=3 at room temperature.The Mn_(1.2)Ga sample exhibits a room temperature magnetization value of 80 emu/g.The hard magnetic properties of coercivityiH_(c)=3.5 kOe,remanence M_(r)=43.6 emu/g,and(BH)_(max)=2.5 MG·Oe were obtained at room temperature.Based on the above studies,we believe that Mn-based magnetic materials could be promising candidates for rare earth free permanent magnets exhibiting a high Curie temperature,high magnetocrystalline anisotropy,and very high coercivity.展开更多
Multiparty private set intersection(PSI)allows several parties,each holding a set of elements,to jointly compute the intersection without leaking any additional information.With the development of cloud computing,PSI ...Multiparty private set intersection(PSI)allows several parties,each holding a set of elements,to jointly compute the intersection without leaking any additional information.With the development of cloud computing,PSI has a wide range of applications in privacy protection.However,it is complex to build an efficient and reliable scheme to protect user privacy.To address this issue,we propose EMPSI,an efficient PSI(with cardinality)protocol in a multiparty setting.EMPSI avoids using heavy cryptographic primitives(mainly rely on symmetric-key encryption)to achieve better performance.In addition,both PSI and PSI with the cardinality of EMPSI are secure against semi-honest adversaries and allow any number of colluding clients(at least one honest client).We also do experiments to compare EMPSI with some state-of-the-art works.The experimental results show that proposed EMPSI(-CA)has better performance and is scalable in the number of clients and the set size.展开更多
Oblivious Cross-Tags(OXT)[1]is the first efficient searchable encryption(SE)protocol for conjunctive queries in a single-writer single-reader framework.However,it also has a trade-off between security and efficiency b...Oblivious Cross-Tags(OXT)[1]is the first efficient searchable encryption(SE)protocol for conjunctive queries in a single-writer single-reader framework.However,it also has a trade-off between security and efficiency by leaking partial database information to the server.Recent attacks on these SE schemes show that the leakages from these SE schemes can be used to recover the content of queried keywords.To solve this problem,Lai et al.[2]propose Hidden Cross-Tags(HXT),which reduces the access pattern leakage from Keyword Pair Result Pattern(KPRP)to Whole Result Pattern(WRP).However,the WRP leakage can also be used to recover some additional contents of queried keywords.This paper proposes Improved Cross-Tags(IXT),an efficient searchable encryption protocol that achieves access and searches pattern hiding based on the labeled private set intersection.We also prove the proposed labeled private set intersection(PSI)protocol is secure against semi-honest adversaries,and IXT is-semi-honest secure(is leakage function).Finally,we do experiments to compare IXT with HXT.The experimental results show that the storage overhead and computation overhead of the search phase at the client-side in IXT is much lower than those in HXT.Meanwhile,the experimental results also show that IXT is scalable and can be applied to various sizes of datasets.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51731001,11805006,51371009,11504348,and 11675006)National Key Research and Development Program of China(Grant Nos.2016YFB0700901,2017YFA0401502,and 2017YFA0206303)
文摘Mn-based intermetallic compounds have attracted much attention due to their fascinating structural and physical properties,especially their interesting hard magnetic properties.In this paper,we have summarized the magnetic and structural properties of Mn-based intermetallic compounds(Mn X,where X=Al,Bi,and Ga).Various methods for synthesizing single phases of MnAl,MnBi,and Mnx Ga were developed in our lab.A very high saturation magnetization of 125 emu/g,coercivity of 5 kOe,and maximum energy product(BH)_(max)of 3.1 MG·Oe were achieved at room temperature for the pureτ-Mn–Al magnetic phase without carbon doping and the extrusion process.Low temperature phase(LTP)MnBi with a purity above 95 wt.%can be synthesized.An abnormal temperature coefficient of the coercivity was observed for the LTP MnBi magnet.Its coercivity increased with temperature from 100 K to 540 K,reached a maximum of 2.5 T at about540 K,and then decreased slowly to 1.8 T at 610 K.The positive temperature coefficient of the coercivity is related to the evolution of the structure and magnetocrystalline anisotropy field of the LTP MnBi phase with temperature.The LTP MnBi bonded magnets show maximum energy products(BH)_(max)of 8.9 MG·Oe(70 kJ/m^(3))and 5.0 MG·Oe(40 k J/m^(3))at room temperature and 400 K,respectively.Ferrimagnetic Mn_(x)Ga phases with L10 structures(x〈2.0)and D0_(22)structures(x〉2.0)were obtained.All of the above structures can be described by a D0_(22)supercell model in which 2 a-Ga and 2 b-Mn are simultaneously substituted.The tetragonal D0_(22)phases of the Mn_(x)Ga show high coercivities ranging from 7.2 kOe for low Mn content x=1.8 to 18.2 kOe for high Mn content x=3 at room temperature.The Mn_(1.2)Ga sample exhibits a room temperature magnetization value of 80 emu/g.The hard magnetic properties of coercivityiH_(c)=3.5 kOe,remanence M_(r)=43.6 emu/g,and(BH)_(max)=2.5 MG·Oe were obtained at room temperature.Based on the above studies,we believe that Mn-based magnetic materials could be promising candidates for rare earth free permanent magnets exhibiting a high Curie temperature,high magnetocrystalline anisotropy,and very high coercivity.
基金supported in part by the National Key Research and Development Program of China(2020YFA0712300)in part by the National Natural Science Foundation of China(Grant Nos.62172162,62132005)。
文摘Multiparty private set intersection(PSI)allows several parties,each holding a set of elements,to jointly compute the intersection without leaking any additional information.With the development of cloud computing,PSI has a wide range of applications in privacy protection.However,it is complex to build an efficient and reliable scheme to protect user privacy.To address this issue,we propose EMPSI,an efficient PSI(with cardinality)protocol in a multiparty setting.EMPSI avoids using heavy cryptographic primitives(mainly rely on symmetric-key encryption)to achieve better performance.In addition,both PSI and PSI with the cardinality of EMPSI are secure against semi-honest adversaries and allow any number of colluding clients(at least one honest client).We also do experiments to compare EMPSI with some state-of-the-art works.The experimental results show that proposed EMPSI(-CA)has better performance and is scalable in the number of clients and the set size.
基金supported in part by the National Key Research and Development Program of China(2020YFA0712300)in part by the National Natural Science Foundation of China(Grant Nos.62172162,62132005)in part by the Shanghai Trusted Industry Internet Software Collaborative Innovation Center.
文摘Oblivious Cross-Tags(OXT)[1]is the first efficient searchable encryption(SE)protocol for conjunctive queries in a single-writer single-reader framework.However,it also has a trade-off between security and efficiency by leaking partial database information to the server.Recent attacks on these SE schemes show that the leakages from these SE schemes can be used to recover the content of queried keywords.To solve this problem,Lai et al.[2]propose Hidden Cross-Tags(HXT),which reduces the access pattern leakage from Keyword Pair Result Pattern(KPRP)to Whole Result Pattern(WRP).However,the WRP leakage can also be used to recover some additional contents of queried keywords.This paper proposes Improved Cross-Tags(IXT),an efficient searchable encryption protocol that achieves access and searches pattern hiding based on the labeled private set intersection.We also prove the proposed labeled private set intersection(PSI)protocol is secure against semi-honest adversaries,and IXT is-semi-honest secure(is leakage function).Finally,we do experiments to compare IXT with HXT.The experimental results show that the storage overhead and computation overhead of the search phase at the client-side in IXT is much lower than those in HXT.Meanwhile,the experimental results also show that IXT is scalable and can be applied to various sizes of datasets.
