An acyclic edge coloring of a graph G is a proper edge coloring such that there are no bichromatic cycles.The acyclic edge chromatic number of a graph G is the minimum number k such that there exists an acyclic edge c...An acyclic edge coloring of a graph G is a proper edge coloring such that there are no bichromatic cycles.The acyclic edge chromatic number of a graph G is the minimum number k such that there exists an acyclic edge coloring using k colors and is denoted by χ’ a（G）.In this paper we prove that χ ’ a（G） ≤（G） ＋ 5 for planar graphs G without adjacent triangles.展开更多
A new acyclic peroxide derivative asperoxide A(1),along with 13 known compounds,namely,microperfuranone(2),9-hydroxymicroperfuranone(3),gibellulin A(4),lecanoric acid(5),terrequinone A(6),sterigmatocystin(7),isosecost...A new acyclic peroxide derivative asperoxide A(1),along with 13 known compounds,namely,microperfuranone(2),9-hydroxymicroperfuranone(3),gibellulin A(4),lecanoric acid(5),terrequinone A(6),sterigmatocystin(7),isosecosterigmatocystin(8),arugosin C(9),curvularin(10),3,3'-diindolylmethane(11),austinol(12),austin(13),and dehydroaustin(14),were isolated and identified from the culture extract of Aspergillus nidulans SD-531,a fungus obtained from the deep-sea sediment of cold spring in the South China Sea.Their structures were determined based on detailed interpretation of nuclear magnetic resonance(NMR)spectroscopic and mass spectrometry data analysis.All the isolated compounds were evaluated for antimicrobial activities against human and aquatic bacteria as well as plant pathogenic fungi.Compounds 1–8,10,and 11 exhibited antimicrobial activities against some of the tested strains with minimum inhibitory concentration(MIC)values ranging from^2 to 64μg/mL.Compounds 4 and 6 displayed strongest activities among the tested samples and might be used as promising molecules for the development of natural antimicrobial agents.展开更多
A proper edge coloring of a graph G is called adjacent vertex-distinguishing acyclic edge coloring if there is no 2-colored cycle in G and the coloring set of edges incident with u is not equal to the coloring set of ...A proper edge coloring of a graph G is called adjacent vertex-distinguishing acyclic edge coloring if there is no 2-colored cycle in G and the coloring set of edges incident with u is not equal to the coloring set of edges incident with v, where uv∈ E（G）. The adjacent vertex distinguishing acyclic edge chromatic number of G, denoted by X＇Aa（G）, is the minimal number of colors in an adjacent vertex distinguishing acyclic edge coloring of G. If a graph G has an adjacent vertex distinguishing acyclic edge coloring, then G is called adjacent vertex distinguishing acyclic. In this paper, we obtain adjacent vertex-distinguishing acyclic edge coloring of some graphs and put forward some conjectures.展开更多
Some new coincidence theorems involving a new class of set-valued mappingscontaining composites of acyclic mappings defined on a contractible space are proved.As applications, some existence theorems of maximal elemen...Some new coincidence theorems involving a new class of set-valued mappingscontaining composites of acyclic mappings defined on a contractible space are proved.As applications, some existence theorems of maximal elements and solutions of abstract variational inequalities, and best approximation theorems are proved. These theorems improve and generalize a number of known results in recent literature.展开更多
A series of novel mono（2,2,2-trifluoroethyl） esters,mono L-amino acid ester prodrugs of acyclic nucleoside phosphonates was synthesized and their in vitro anti-HBVactivity was evaluated in HepG 2 2.2.15 cells.Compou...A series of novel mono（2,2,2-trifluoroethyl） esters,mono L-amino acid ester prodrugs of acyclic nucleoside phosphonates was synthesized and their in vitro anti-HBVactivity was evaluated in HepG 2 2.2.15 cells.Compound 1d exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil and alamifovir（MCC-478） with EC_（50） and CC_（50） values of 0.01μmol/L and 8000μmol/L respectively.展开更多
Herein we reported that ferrocene-containing polymers could be synthesized via acyclic diene metathesis （ADMET） polymerization of ferrocene-containing bis-styryl monomers. The all-trans-configured vinylene bonds of ...Herein we reported that ferrocene-containing polymers could be synthesized via acyclic diene metathesis （ADMET） polymerization of ferrocene-containing bis-styryl monomers. The all-trans-configured vinylene bonds of stilbene segment were proven by means of ^13C-NMR, ^1H-NMR, MALDI-TOF mass spectrometry and FTIR. Poly（1） showed maxima for absorption at 320 nm and emission at 430 nm which are structurally very similar to trans-stilbene, but 24 and 16 nm red shifted respectively. CIE chromaticity diagram shows that emission color could be adjusted by controlling the molecular weight. The polymer showed excellent solubility in common organic solvents and good thermal stability evidenced by TGA and DSC. The results of CV suggested the polymer possessed noninteracting metal centers which was confirmed by a reversible one-electron redox wave observed for the polymer.展开更多
Eight novel heterobinuclear complexes of Ln3+ and Zn2+ with salicylidene diethylene glycol diamine(SALDA) Schiff base (NO3)22H2O(Ln=Pr, Nd, Sm, Gd, Tb, Er, Yb, Y) were synthesized and characterized on the basis of IR...Eight novel heterobinuclear complexes of Ln3+ and Zn2+ with salicylidene diethylene glycol diamine(SALDA) Schiff base (NO3)22H2O(Ln=Pr, Nd, Sm, Gd, Tb, Er, Yb, Y) were synthesized and characterized on the basis of IR and UV, particularly by1H and13C NMR spectra. It is confirmed that the azomethine nitrogen, ethereal oxygen and a part of phenolic oxygen atoms coordinate to the central ions.展开更多
A series of novel L-amino acid esters prodrugs of acyclic nucleoside phosphonates was synthesized and their anti-HBV activity was evaluated in HepG2 2.2.15 cells. Compound 1d exhibited more potent anti-HBV activity an...A series of novel L-amino acid esters prodrugs of acyclic nucleoside phosphonates was synthesized and their anti-HBV activity was evaluated in HepG2 2.2.15 cells. Compound 1d exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil with EC50 and CC50 values of 0.207 μmol/L and 2530 μmol/L, respectively.展开更多
Based on the framework of support vector machines （SVM） using one-against-one （OAO） strategy, a new multi-class kernel method based on directed aeyclie graph （DAG） and probabilistic distance is proposed to raise...Based on the framework of support vector machines （SVM） using one-against-one （OAO） strategy, a new multi-class kernel method based on directed aeyclie graph （DAG） and probabilistic distance is proposed to raise the multi-class classification accuracies. The topology structure of DAG is constructed by rearranging the nodes＇ sequence in the graph. DAG is equivalent to guided operating SVM on a list, and the classification performance depends on the nodes＇ sequence in the graph. Jeffries-Matusita distance （JMD） is introduced to estimate the separability of each class, and the implementation list is initialized with all classes organized according to certain sequence in the list. To testify the effectiveness of the proposed method, numerical analysis is conducted on UCI data and hyperspectral data. Meanwhile, comparative studies using standard OAO and DAG classification methods are also conducted and the results illustrate better performance and higher accuracy of the orooosed JMD-DAG method.展开更多
A proper edge colouring f of a graph G is called acyclic if there are no bichromatic cycles in the graph. The acyclic edge chromatic number or acyclic chromatic index, denoted by , is the minimum number of colours in ...A proper edge colouring f of a graph G is called acyclic if there are no bichromatic cycles in the graph. The acyclic edge chromatic number or acyclic chromatic index, denoted by , is the minimum number of colours in an acyclic edge colouring of G. In this paper, we discuss the acyclic edge colouring of middle, central, total and line graphs of prime related star graph families. Also exact values of acyclic chromatic indices of such graphs are derived and some of their structural properties are discussed.展开更多
A nickel(Ⅱ)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions generated in situ from corresponding acetals with carboxylic acid derivatives to prepareβ-alkoxyl carbonyl moieties with diverseα-substituent...A nickel(Ⅱ)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions generated in situ from corresponding acetals with carboxylic acid derivatives to prepareβ-alkoxyl carbonyl moieties with diverseα-substituents has been disclosed.The method exhibited broad scope of acetals and carboxylic acid derivatives with excellent enantioselectivity and good functional group compatibility,and can be conducted in a gram-scale without obvious loss of efficiency.展开更多
Aphamines A-C(1-3),three pairs of acyclic diterpene dimer enantiomers with an unprecedent ploymerization pattern,were discovered from Aphanamixis polystachya by NMR-guided isolation and chiral resolution.The elucidati...Aphamines A-C(1-3),three pairs of acyclic diterpene dimer enantiomers with an unprecedent ploymerization pattern,were discovered from Aphanamixis polystachya by NMR-guided isolation and chiral resolution.The elucidation of their novel carbon skeletons was achieved based on spectroscopic analysis,exciton chirality,and calculated electronic circular dichroism(ECD).Plausible Claisen rearrangement,5-exo-trig cyclization,and reduction reactions may play important roles in the polymeric biosynthesis pathway.Compounds 1 and 3 showed inhibitory effects on nitric oxide(NO)production(IC_(50):6.71-15.36 μmol/L) and reduced the expression of iNOS in LPS-induced RAW 264.7 macrophages.展开更多
Introduces the concepts of strict conflict free and extended strict conflict free,proves decomposition satisfies lossless join,keep dependency, β acyclic and 4NF if and only if Γ is extended strict conflict free in ...Introduces the concepts of strict conflict free and extended strict conflict free,proves decomposition satisfies lossless join,keep dependency, β acyclic and 4NF if and only if Γ is extended strict conflict free in the mixed environment,proposes the algorithm of getting degenerated MVDS sets,judging conflict free,judging stric conflict free and β acyclic decomposition in mixed environment,and illustrates with an example that the complexity of algorithm is linear.展开更多
Some new coincidence theorem s involving a new class of set_valued mappings containing composites of acyclic mappings defined in a contractible space are proved. For applications, some best approximation theorems an...Some new coincidence theorem s involving a new class of set_valued mappings containing composites of acyclic mappings defined in a contractible space are proved. For applications, some best approximation theorems and coincidence theorems for set-valued mappings are als o given. A number of known results in recent literature are improved and general ized by the theorems in this paper.展开更多
We present a method of test generation for acyclic sequential circuits with hold registers. A complete (100% fault efficiency) test sequence for an acyclic sequential circuit can be obtained by applying a combinationa...We present a method of test generation for acyclic sequential circuits with hold registers. A complete (100% fault efficiency) test sequence for an acyclic sequential circuit can be obtained by applying a combinational test generator to all the maximal time-expansion models (TEMs) of the circuit. We propose a class of acyclic sequential circuits for which the number of maximal TEMs is one, i.e, the maximum TEM exists. For a circuit in the class, test generation can be performed by using only the maximum TEM. The proposed class of sequential circuits with the maximum TEM properly includes several known classes of acyclic sequential circuits such as balanced structures and acyclic sequential circuits without hold registers for which test generation can be also performed by using a combinational test generator. Therefore, in general, the hardware overhead for partial scan based on the proposed structure is smaller than that based on balanced or acyclic sequential structure without hold registers.展开更多
Peer-to-peer(P2P)spectrum sharing and energy trading are promising solutions to locally satisfy spectrum and energy demands in power Internet of Things(IoT).However,implementation of largescale P2P spectrum sharing an...Peer-to-peer(P2P)spectrum sharing and energy trading are promising solutions to locally satisfy spectrum and energy demands in power Internet of Things(IoT).However,implementation of largescale P2P spectrum sharing and energy trading confronts security and privacy challenges.In this paper,we exploit consortium blockchain and Directed Acyclic Graph(DAG)to propose a new secure and distributed spectrum sharing and energy trading framework in power IoT,named spectrum-energy chain,where a set of local aggregators(LAGs)cooperatively confirm the identity of the power devices by utilizing consortium blockchain,so as to form a main chain.Then,the local power devices verify spectrum and energy micro-transactions simultaneously but asynchronously to form local spectrum tangle and local energy tangle,respectively.Moreover,an iterative double auction based micro transactions scheme is designed to solve the spectrum and energy pricing and the amount of shared spectrum and energy among power devices.Security analysis and numerical results illustrate that the developed spectrum-energy chain and the designed iterative double auction based microtransactions scheme are secure and efficient for spectrum sharing and energy trading in power IoT.展开更多
In this paper, we investigated the selective cleavage of acyclic acetals with the reagent system, ZrCl_4-LiAlH_4. The results indicate that this system is very useful for the cleavage of acyclic acetals to the corresp...In this paper, we investigated the selective cleavage of acyclic acetals with the reagent system, ZrCl_4-LiAlH_4. The results indicate that this system is very useful for the cleavage of acyclic acetals to the corresponding asymmetric ethers.展开更多
The wide application of intelligent terminals in microgrids has fueled the surge of data amount in recent years.In real-world scenarios,microgrids must store large amounts of data efficiently while also being able to ...The wide application of intelligent terminals in microgrids has fueled the surge of data amount in recent years.In real-world scenarios,microgrids must store large amounts of data efficiently while also being able to withstand malicious cyberattacks.To meet the high hardware resource requirements,address the vulnerability to network attacks and poor reliability in the tradi-tional centralized data storage schemes,this paper proposes a secure storage management method for microgrid data that considers node trust and directed acyclic graph(DAG)consensus mechanism.Firstly,the microgrid data storage model is designed based on the edge computing technology.The blockchain,deployed on the edge computing server and combined with cloud storage,ensures reliable data storage in the microgrid.Secondly,a blockchain consen-sus algorithm based on directed acyclic graph data structure is then proposed to effectively improve the data storage timeliness and avoid disadvantages in traditional blockchain topology such as long chain construction time and low consensus efficiency.Finally,considering the tolerance differences among the candidate chain-building nodes to network attacks,a hash value update mechanism of blockchain header with node trust identification to ensure data storage security is proposed.Experimental results from the microgrid data storage platform show that the proposed method can achieve a private key update time of less than 5 milliseconds.When the number of blockchain nodes is less than 25,the blockchain construction takes no more than 80 mins,and the data throughput is close to 300 kbps.Compared with the traditional chain-topology-based consensus methods that do not consider node trust,the proposed method has higher efficiency in data storage and better resistance to network attacks.展开更多
Two new acyclic diterpene-g-lactones named hanliuine III (1) and hanliuine IV (2) were isolated from leaves of Salix matsudana (Chinese name 揾anliu?. Their structures were deduced from spectral data.
文摘An acyclic edge coloring of a graph G is a proper edge coloring such that there are no bichromatic cycles.The acyclic edge chromatic number of a graph G is the minimum number k such that there exists an acyclic edge coloring using k colors and is denoted by χ’ a（G）.In this paper we prove that χ ’ a（G） ≤（G） ＋ 5 for planar graphs G without adjacent triangles.
基金the National Key R&D Program of China(No.2018YFC0310800)。
文摘A new acyclic peroxide derivative asperoxide A(1),along with 13 known compounds,namely,microperfuranone(2),9-hydroxymicroperfuranone(3),gibellulin A(4),lecanoric acid(5),terrequinone A(6),sterigmatocystin(7),isosecosterigmatocystin(8),arugosin C(9),curvularin(10),3,3'-diindolylmethane(11),austinol(12),austin(13),and dehydroaustin(14),were isolated and identified from the culture extract of Aspergillus nidulans SD-531,a fungus obtained from the deep-sea sediment of cold spring in the South China Sea.Their structures were determined based on detailed interpretation of nuclear magnetic resonance(NMR)spectroscopic and mass spectrometry data analysis.All the isolated compounds were evaluated for antimicrobial activities against human and aquatic bacteria as well as plant pathogenic fungi.Compounds 1–8,10,and 11 exhibited antimicrobial activities against some of the tested strains with minimum inhibitory concentration(MIC)values ranging from^2 to 64μg/mL.Compounds 4 and 6 displayed strongest activities among the tested samples and might be used as promising molecules for the development of natural antimicrobial agents.
基金supported by NSFC of China (No. 19871036 and No. 40301037)Faculty Research Grant,Hong Kong Baptist University
文摘A proper edge coloring of a graph G is called adjacent vertex-distinguishing acyclic edge coloring if there is no 2-colored cycle in G and the coloring set of edges incident with u is not equal to the coloring set of edges incident with v, where uv∈ E（G）. The adjacent vertex distinguishing acyclic edge chromatic number of G, denoted by X＇Aa（G）, is the minimal number of colors in an adjacent vertex distinguishing acyclic edge coloring of G. If a graph G has an adjacent vertex distinguishing acyclic edge coloring, then G is called adjacent vertex distinguishing acyclic. In this paper, we obtain adjacent vertex-distinguishing acyclic edge coloring of some graphs and put forward some conjectures.
文摘Some new coincidence theorems involving a new class of set-valued mappingscontaining composites of acyclic mappings defined on a contractible space are proved.As applications, some existence theorems of maximal elements and solutions of abstract variational inequalities, and best approximation theorems are proved. These theorems improve and generalize a number of known results in recent literature.
基金supported by the grants from the National Natural Science Foundation of China(No.20962004)the Provincial Social Development Foundation of Guizhou,China(No.QKHSYZ[2009]3081)+1 种基金Provincial Special Assistant Foundation for High-level Talents of Guizhou,China(No.TZJF-2009-36)Science and Technology Foundation of Guizhou Province,China(No.QKHJZ[2008]2140)
文摘A series of novel mono（2,2,2-trifluoroethyl） esters,mono L-amino acid ester prodrugs of acyclic nucleoside phosphonates was synthesized and their in vitro anti-HBVactivity was evaluated in HepG 2 2.2.15 cells.Compound 1d exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil and alamifovir（MCC-478） with EC_（50） and CC_（50） values of 0.01μmol/L and 8000μmol/L respectively.
基金financially supported by the National Natural Science Foundation of China(No.21364005)Startup Foundation for Outstanding Young Scientists of Inner Mongolia University(Z20080213No.115110)
文摘Herein we reported that ferrocene-containing polymers could be synthesized via acyclic diene metathesis （ADMET） polymerization of ferrocene-containing bis-styryl monomers. The all-trans-configured vinylene bonds of stilbene segment were proven by means of ^13C-NMR, ^1H-NMR, MALDI-TOF mass spectrometry and FTIR. Poly（1） showed maxima for absorption at 320 nm and emission at 430 nm which are structurally very similar to trans-stilbene, but 24 and 16 nm red shifted respectively. CIE chromaticity diagram shows that emission color could be adjusted by controlling the molecular weight. The polymer showed excellent solubility in common organic solvents and good thermal stability evidenced by TGA and DSC. The results of CV suggested the polymer possessed noninteracting metal centers which was confirmed by a reversible one-electron redox wave observed for the polymer.
文摘Eight novel heterobinuclear complexes of Ln3+ and Zn2+ with salicylidene diethylene glycol diamine(SALDA) Schiff base (NO3)22H2O(Ln=Pr, Nd, Sm, Gd, Tb, Er, Yb, Y) were synthesized and characterized on the basis of IR and UV, particularly by1H and13C NMR spectra. It is confirmed that the azomethine nitrogen, ethereal oxygen and a part of phenolic oxygen atoms coordinate to the central ions.
文摘A series of novel L-amino acid esters prodrugs of acyclic nucleoside phosphonates was synthesized and their anti-HBV activity was evaluated in HepG2 2.2.15 cells. Compound 1d exhibited more potent anti-HBV activity and lower cytotoxicity than those of adefovir dipivoxil with EC50 and CC50 values of 0.207 μmol/L and 2530 μmol/L, respectively.
基金Sponsored by the National Natural Science Foundation of China(Grant No.61201310)the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.201160)the China Postdoctoral Science Foundation(Grant No.20110491067)
文摘Based on the framework of support vector machines （SVM） using one-against-one （OAO） strategy, a new multi-class kernel method based on directed aeyclie graph （DAG） and probabilistic distance is proposed to raise the multi-class classification accuracies. The topology structure of DAG is constructed by rearranging the nodes＇ sequence in the graph. DAG is equivalent to guided operating SVM on a list, and the classification performance depends on the nodes＇ sequence in the graph. Jeffries-Matusita distance （JMD） is introduced to estimate the separability of each class, and the implementation list is initialized with all classes organized according to certain sequence in the list. To testify the effectiveness of the proposed method, numerical analysis is conducted on UCI data and hyperspectral data. Meanwhile, comparative studies using standard OAO and DAG classification methods are also conducted and the results illustrate better performance and higher accuracy of the orooosed JMD-DAG method.
文摘A proper edge colouring f of a graph G is called acyclic if there are no bichromatic cycles in the graph. The acyclic edge chromatic number or acyclic chromatic index, denoted by , is the minimum number of colours in an acyclic edge colouring of G. In this paper, we discuss the acyclic edge colouring of middle, central, total and line graphs of prime related star graph families. Also exact values of acyclic chromatic indices of such graphs are derived and some of their structural properties are discussed.
基金financial supported by the Natural Science Foundation of China(Nos.21722204,21971148)Fok Ying Tung Education Foundation(No.151035)。
文摘A nickel(Ⅱ)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions generated in situ from corresponding acetals with carboxylic acid derivatives to prepareβ-alkoxyl carbonyl moieties with diverseα-substituents has been disclosed.The method exhibited broad scope of acetals and carboxylic acid derivatives with excellent enantioselectivity and good functional group compatibility,and can be conducted in a gram-scale without obvious loss of efficiency.
基金Financial support for this study is from the National Natural Science Foundation of China (No.31470416)the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT_15R63)+2 种基金the "Double First-Class" University Project,China (No.CPU2018GY08)the 111 Project from Ministry of Education ofChina and the State Administration of Foreign Export Affairs of China (No.B18056)the National New Drug Innovation Major Project (No.2018ZX09711-001-007)。
文摘Aphamines A-C(1-3),three pairs of acyclic diterpene dimer enantiomers with an unprecedent ploymerization pattern,were discovered from Aphanamixis polystachya by NMR-guided isolation and chiral resolution.The elucidation of their novel carbon skeletons was achieved based on spectroscopic analysis,exciton chirality,and calculated electronic circular dichroism(ECD).Plausible Claisen rearrangement,5-exo-trig cyclization,and reduction reactions may play important roles in the polymeric biosynthesis pathway.Compounds 1 and 3 showed inhibitory effects on nitric oxide(NO)production(IC_(50):6.71-15.36 μmol/L) and reduced the expression of iNOS in LPS-induced RAW 264.7 macrophages.
文摘Introduces the concepts of strict conflict free and extended strict conflict free,proves decomposition satisfies lossless join,keep dependency, β acyclic and 4NF if and only if Γ is extended strict conflict free in the mixed environment,proposes the algorithm of getting degenerated MVDS sets,judging conflict free,judging stric conflict free and β acyclic decomposition in mixed environment,and illustrates with an example that the complexity of algorithm is linear.
文摘Some new coincidence theorem s involving a new class of set_valued mappings containing composites of acyclic mappings defined in a contractible space are proved. For applications, some best approximation theorems and coincidence theorems for set-valued mappings are als o given. A number of known results in recent literature are improved and general ized by the theorems in this paper.
文摘We present a method of test generation for acyclic sequential circuits with hold registers. A complete (100% fault efficiency) test sequence for an acyclic sequential circuit can be obtained by applying a combinational test generator to all the maximal time-expansion models (TEMs) of the circuit. We propose a class of acyclic sequential circuits for which the number of maximal TEMs is one, i.e, the maximum TEM exists. For a circuit in the class, test generation can be performed by using only the maximum TEM. The proposed class of sequential circuits with the maximum TEM properly includes several known classes of acyclic sequential circuits such as balanced structures and acyclic sequential circuits without hold registers for which test generation can be also performed by using a combinational test generator. Therefore, in general, the hardware overhead for partial scan based on the proposed structure is smaller than that based on balanced or acyclic sequential structure without hold registers.
基金supported by the National Key R&D Program of China(2020YFB1807801,2020YFB1807800)in part by Project Supported by Engineering Research Center of Mobile Communications,Ministry of Education(cqupt-mct-202003)+2 种基金in part by Key Lab of Information Network Security,Ministry of Public Security under Grant C19603in part by National Natural Science Foundation of China(Grant No.61901067 and 61901013)in part by Chongqing Municipal Natural Science Foundation(Grant No.cstc2020jcyj-msxmX0339).
文摘Peer-to-peer(P2P)spectrum sharing and energy trading are promising solutions to locally satisfy spectrum and energy demands in power Internet of Things(IoT).However,implementation of largescale P2P spectrum sharing and energy trading confronts security and privacy challenges.In this paper,we exploit consortium blockchain and Directed Acyclic Graph(DAG)to propose a new secure and distributed spectrum sharing and energy trading framework in power IoT,named spectrum-energy chain,where a set of local aggregators(LAGs)cooperatively confirm the identity of the power devices by utilizing consortium blockchain,so as to form a main chain.Then,the local power devices verify spectrum and energy micro-transactions simultaneously but asynchronously to form local spectrum tangle and local energy tangle,respectively.Moreover,an iterative double auction based micro transactions scheme is designed to solve the spectrum and energy pricing and the amount of shared spectrum and energy among power devices.Security analysis and numerical results illustrate that the developed spectrum-energy chain and the designed iterative double auction based microtransactions scheme are secure and efficient for spectrum sharing and energy trading in power IoT.
文摘In this paper, we investigated the selective cleavage of acyclic acetals with the reagent system, ZrCl_4-LiAlH_4. The results indicate that this system is very useful for the cleavage of acyclic acetals to the corresponding asymmetric ethers.
文摘The wide application of intelligent terminals in microgrids has fueled the surge of data amount in recent years.In real-world scenarios,microgrids must store large amounts of data efficiently while also being able to withstand malicious cyberattacks.To meet the high hardware resource requirements,address the vulnerability to network attacks and poor reliability in the tradi-tional centralized data storage schemes,this paper proposes a secure storage management method for microgrid data that considers node trust and directed acyclic graph(DAG)consensus mechanism.Firstly,the microgrid data storage model is designed based on the edge computing technology.The blockchain,deployed on the edge computing server and combined with cloud storage,ensures reliable data storage in the microgrid.Secondly,a blockchain consen-sus algorithm based on directed acyclic graph data structure is then proposed to effectively improve the data storage timeliness and avoid disadvantages in traditional blockchain topology such as long chain construction time and low consensus efficiency.Finally,considering the tolerance differences among the candidate chain-building nodes to network attacks,a hash value update mechanism of blockchain header with node trust identification to ensure data storage security is proposed.Experimental results from the microgrid data storage platform show that the proposed method can achieve a private key update time of less than 5 milliseconds.When the number of blockchain nodes is less than 25,the blockchain construction takes no more than 80 mins,and the data throughput is close to 300 kbps.Compared with the traditional chain-topology-based consensus methods that do not consider node trust,the proposed method has higher efficiency in data storage and better resistance to network attacks.
文摘Two new acyclic diterpene-g-lactones named hanliuine III (1) and hanliuine IV (2) were isolated from leaves of Salix matsudana (Chinese name 揾anliu?. Their structures were deduced from spectral data.
