In this paper,we address the problem of constructing a Steiner tree in the Euclidean plane R^(2)using stock pieces of materials with fixed length,which is modelled as follows.Given a set X={r_(1),r_(2)…,r_(n)}of n te...In this paper,we address the problem of constructing a Steiner tree in the Euclidean plane R^(2)using stock pieces of materials with fixed length,which is modelled as follows.Given a set X={r_(1),r_(2)…,r_(n)}of n terminals in R^(2)and some stock pieces of materials with fixed length L,we are asked to construct a Steiner tree T interconnecting all terminals in X,and each edge in T must be constructed by a part of that stock piece of material.The objective is to minimize the cost of constructing such a Steiner tree T,where the cost includes three components,(1)The cost of Steiner points needed in T;(2)The construction cost of constructing all edges in T and(3)The cost of stock pieces of such materials used to construct all edges in T.We can obtain two main results.(1)Using techniques of constructing a Euclidean minimum spanning tree on the set X and a strategy of solving the bin-packing problem,we present a simple 4-approximation algorithm in time O(n log n)to solve this new problem;(2)Using techniques of computational geometry to solve two nonlinear mathematical programming to obtain a key Lemma 8 and using other strategy of solving the bin-packing problem,we design a 3-approximation algorithm in time O(n^(3))to resolve this new problem.展开更多
It is of great significance to improve the efficiency of railway production and operation by realizing the fault knowledge association through the efficient data mining algorithm.However,high utility quantitative freq...It is of great significance to improve the efficiency of railway production and operation by realizing the fault knowledge association through the efficient data mining algorithm.However,high utility quantitative frequent pattern mining algorithms in the field of data mining still suffer from the problems of low time-memory performance and are not easy to scale up.In the context of such needs,we propose a related degree-based frequent pattern mining algorithm,named Related High Utility Quantitative Item set Mining(RHUQI-Miner),to enable the effective mining of railway fault data.The algorithm constructs the item-related degree structure of fault data and gives a pruning optimization strategy to find frequent patterns with higher related degrees,reducing redundancy and invalid frequent patterns.Subsequently,it uses the fixed pattern length strategy to modify the utility information of the item in the mining process so that the algorithm can control the length of the output frequent pattern according to the actual data situation and further improve the performance and practicability of the algorithm.The experimental results on the real fault dataset show that RHUQI-Miner can effectively reduce the time and memory consumption in the mining process,thus providing data support for differentiated and precise maintenance strategies.展开更多
To provide a high-security guaran- tee to network coding and lower the comput- ing complexity induced by signature scheme, we take full advantage of homomorphic prop- erty to build lattice signature schemes and sec- u...To provide a high-security guaran- tee to network coding and lower the comput- ing complexity induced by signature scheme, we take full advantage of homomorphic prop- erty to build lattice signature schemes and sec- ure network coding algorithms. Firstly, by means of the distance between the message and its sig- nature in a lattice, we propose a Distance-bas- ed Secure Network Coding （DSNC） algorithm and stipulate its security to a new hard problem Fixed Length Vector Problem （FLVP）, which is harder than Shortest Vector Problem （SVP） on lattices. Secondly, considering the bound- ary on the distance between the message and its signature, we further propose an efficient Bo- undary-based Secure Network Coding （BSNC） algorithm to reduce the computing complexity induced by square calculation in DSNC. Sim- ulation results and security analysis show that the proposed signature schemes have stronger unforgeability due to the natural property of lattices than traditional Rivest-Shamir-Adleman （RSA）-based signature scheme. DSNC algo- rithm is more secure and BSNC algorithm greatly reduces the time cost on computation.展开更多
In order to study cavitation characteristics of a 2-D hydrofoil, the method that combines nonlinear cavitation model and mixed-iteration is used to predict and analyze the cavitation performance of hydrofoils. The cav...In order to study cavitation characteristics of a 2-D hydrofoil, the method that combines nonlinear cavitation model and mixed-iteration is used to predict and analyze the cavitation performance of hydrofoils. The cavitation elements are nonlinearly disposed based on the Green formula and perturbation potential panel method. At the same time, the method that combines cavity shape for fixed cavity length （CSCL） iteration and cavity shape for fixed cavitation number （CSCN） iteration is used to work out the thickness and length of hydrofoil cavitations. Through analysis of calculation results, it can be concluded that the jump of pressure and velocity potentially exist between cavitation end area and non-cavitations area on suction surface when cavitation occurs on hydrofoil. In certain angles of attack, the cavitation number has a negative impact on the length of cavitations. And under the same angle of attack and cavitation number, the bigger the thickness of the hydrofoil, the shorter the cavitations length.展开更多
In this paper, we propose a new OBS scheme, named Fixed Burst Length OBS. The FBL-OBS networks, combined with the extra-offset time scheme, can guarantee the QoS of OBS networks in a more efficient way.
基金supported by the National Natural Science Foundation of China(Nos.11861075 and 12101593)Project for Innovation Team(Cultivation)of Yunnan Province(No.202005AE160006)+1 种基金supported by Fundamental Research Funds for the Central Universities(No.buctrc202219)supported by Project of Yunling Scholars Training of Yunnan Province(No.K264202011820).
文摘In this paper,we address the problem of constructing a Steiner tree in the Euclidean plane R^(2)using stock pieces of materials with fixed length,which is modelled as follows.Given a set X={r_(1),r_(2)…,r_(n)}of n terminals in R^(2)and some stock pieces of materials with fixed length L,we are asked to construct a Steiner tree T interconnecting all terminals in X,and each edge in T must be constructed by a part of that stock piece of material.The objective is to minimize the cost of constructing such a Steiner tree T,where the cost includes three components,(1)The cost of Steiner points needed in T;(2)The construction cost of constructing all edges in T and(3)The cost of stock pieces of such materials used to construct all edges in T.We can obtain two main results.(1)Using techniques of constructing a Euclidean minimum spanning tree on the set X and a strategy of solving the bin-packing problem,we present a simple 4-approximation algorithm in time O(n log n)to solve this new problem;(2)Using techniques of computational geometry to solve two nonlinear mathematical programming to obtain a key Lemma 8 and using other strategy of solving the bin-packing problem,we design a 3-approximation algorithm in time O(n^(3))to resolve this new problem.
基金supported by the Research on Key Technologies and Typical Applications of Big Data in Railway Production and Operation(P2023S006)the Fundamental Research Funds for the Central Universities(2022JBZY023).
文摘It is of great significance to improve the efficiency of railway production and operation by realizing the fault knowledge association through the efficient data mining algorithm.However,high utility quantitative frequent pattern mining algorithms in the field of data mining still suffer from the problems of low time-memory performance and are not easy to scale up.In the context of such needs,we propose a related degree-based frequent pattern mining algorithm,named Related High Utility Quantitative Item set Mining(RHUQI-Miner),to enable the effective mining of railway fault data.The algorithm constructs the item-related degree structure of fault data and gives a pruning optimization strategy to find frequent patterns with higher related degrees,reducing redundancy and invalid frequent patterns.Subsequently,it uses the fixed pattern length strategy to modify the utility information of the item in the mining process so that the algorithm can control the length of the output frequent pattern according to the actual data situation and further improve the performance and practicability of the algorithm.The experimental results on the real fault dataset show that RHUQI-Miner can effectively reduce the time and memory consumption in the mining process,thus providing data support for differentiated and precise maintenance strategies.
基金ACKNOWLEDGEMENT This work was partially supported by the National Basic Research Program of China under Grant No. 2012CB315905 the National Natural Sci- ence Foundation of China under Grants No. 61272501, No. 61173154, No. 61370190 and the Beijing Natural Science Foundation under Grant No. 4132056.
文摘To provide a high-security guaran- tee to network coding and lower the comput- ing complexity induced by signature scheme, we take full advantage of homomorphic prop- erty to build lattice signature schemes and sec- ure network coding algorithms. Firstly, by means of the distance between the message and its sig- nature in a lattice, we propose a Distance-bas- ed Secure Network Coding （DSNC） algorithm and stipulate its security to a new hard problem Fixed Length Vector Problem （FLVP）, which is harder than Shortest Vector Problem （SVP） on lattices. Secondly, considering the bound- ary on the distance between the message and its signature, we further propose an efficient Bo- undary-based Secure Network Coding （BSNC） algorithm to reduce the computing complexity induced by square calculation in DSNC. Sim- ulation results and security analysis show that the proposed signature schemes have stronger unforgeability due to the natural property of lattices than traditional Rivest-Shamir-Adleman （RSA）-based signature scheme. DSNC algo- rithm is more secure and BSNC algorithm greatly reduces the time cost on computation.
基金Supported by the National Natural Science Foundation of China （Grant No. 41176074） China Postdoctoral Science Foundation （Grant No.2012M512133） Specialized Research Fund for the Doctoral Program of Higher Education （Grant No.20102304120026）
文摘In order to study cavitation characteristics of a 2-D hydrofoil, the method that combines nonlinear cavitation model and mixed-iteration is used to predict and analyze the cavitation performance of hydrofoils. The cavitation elements are nonlinearly disposed based on the Green formula and perturbation potential panel method. At the same time, the method that combines cavity shape for fixed cavity length （CSCL） iteration and cavity shape for fixed cavitation number （CSCN） iteration is used to work out the thickness and length of hydrofoil cavitations. Through analysis of calculation results, it can be concluded that the jump of pressure and velocity potentially exist between cavitation end area and non-cavitations area on suction surface when cavitation occurs on hydrofoil. In certain angles of attack, the cavitation number has a negative impact on the length of cavitations. And under the same angle of attack and cavitation number, the bigger the thickness of the hydrofoil, the shorter the cavitations length.
文摘In this paper, we propose a new OBS scheme, named Fixed Burst Length OBS. The FBL-OBS networks, combined with the extra-offset time scheme, can guarantee the QoS of OBS networks in a more efficient way.
