This article is an addendum to the 2001 paper [1] which investigated an approach to hierarchical clustering based on the level sets of a density function induced on data points in a d-dimensional feature space. We ref...This article is an addendum to the 2001 paper [1] which investigated an approach to hierarchical clustering based on the level sets of a density function induced on data points in a d-dimensional feature space. We refer to this as the “level-sets approach” to hierarchical clustering. The density functions considered in [1] were those formed as the sum of identical radial basis functions centered at the data points, each radial basis function assumed to be continuous, monotone decreasing, convex on every ray, and rising to positive infinity at its center point. Such a framework can be investigated with respect to both the Euclidean (L2) and Manhattan (L1) metrics. The addendum here puts forth some observations and questions about the level-sets approach that go beyond those in [1]. In particular, we detail and ask the following questions. How does the level-sets approach compare with other related approaches? How is the resulting hierarchical clustering affected by the choice of radial basis function? What are the structural properties of a function formed as the sum of radial basis functions? Can the levels-sets approach be theoretically validated? Is there an efficient algorithm to implement the level-sets approach?展开更多
The Server-Based Certificate Validation Protocol allows PKI clients to delegate to a server the construction or validation of certification paths. The protocol’s specification focuses on the communication between the...The Server-Based Certificate Validation Protocol allows PKI clients to delegate to a server the construction or validation of certification paths. The protocol’s specification focuses on the communication between the server and the client and its security. It does not discuss how the servers can efficiently locate the necessary PKI resources like certificate or certificate revocation lists. In this paper we concentrate on this topic. We present a simple and effective method to facilitate locating and using various PKI resources by the servers, without modifying the protocol. We use the extension mechanism of the protocol for notifying the servers about PKI repositories, certificates, and revocations. We specify the tasks of the servers and certificate issu-ers and define the messages that are exchanged between them. A proof of concept is given by implementing an SCVP server, a client, and the proposed method in Java.展开更多
This paper studies the transfer path planning problem for safe transfer of an aircraft on the aircraft carrier flight deck under a poor visibility condition or at night.First,we analyze the transfer path planning prob...This paper studies the transfer path planning problem for safe transfer of an aircraft on the aircraft carrier flight deck under a poor visibility condition or at night.First,we analyze the transfer path planning problem for carrier-based aircraft on the flight deck,and define the objective to be optimized and the constraints to be met.Second,to solve this problem,the mathematical support models for the flight deck,carrier aircraft entity,entity extension,entity posture,entity conflict detection,and path smoothing are established,as they provide the necessary basis for transfer path planning of the aircraft on the aircraft carrier.Third,to enable automatic transfer path planning,we design a multi-habitat parallel chaos algorithm(called KCMPSO),and use it as the optimization method for transfer path planning.Finally,we take the Kuznetsov aircraft carrier as a verification example,and conduct simulations.The simulation results show that compared with particle swarm optimization,this method can solve the transfer path planning problem for an aircraft on the aircraft carrier flight deck better.展开更多
文摘This article is an addendum to the 2001 paper [1] which investigated an approach to hierarchical clustering based on the level sets of a density function induced on data points in a d-dimensional feature space. We refer to this as the “level-sets approach” to hierarchical clustering. The density functions considered in [1] were those formed as the sum of identical radial basis functions centered at the data points, each radial basis function assumed to be continuous, monotone decreasing, convex on every ray, and rising to positive infinity at its center point. Such a framework can be investigated with respect to both the Euclidean (L2) and Manhattan (L1) metrics. The addendum here puts forth some observations and questions about the level-sets approach that go beyond those in [1]. In particular, we detail and ask the following questions. How does the level-sets approach compare with other related approaches? How is the resulting hierarchical clustering affected by the choice of radial basis function? What are the structural properties of a function formed as the sum of radial basis functions? Can the levels-sets approach be theoretically validated? Is there an efficient algorithm to implement the level-sets approach?
文摘The Server-Based Certificate Validation Protocol allows PKI clients to delegate to a server the construction or validation of certification paths. The protocol’s specification focuses on the communication between the server and the client and its security. It does not discuss how the servers can efficiently locate the necessary PKI resources like certificate or certificate revocation lists. In this paper we concentrate on this topic. We present a simple and effective method to facilitate locating and using various PKI resources by the servers, without modifying the protocol. We use the extension mechanism of the protocol for notifying the servers about PKI repositories, certificates, and revocations. We specify the tasks of the servers and certificate issu-ers and define the messages that are exchanged between them. A proof of concept is given by implementing an SCVP server, a client, and the proposed method in Java.
文摘This paper studies the transfer path planning problem for safe transfer of an aircraft on the aircraft carrier flight deck under a poor visibility condition or at night.First,we analyze the transfer path planning problem for carrier-based aircraft on the flight deck,and define the objective to be optimized and the constraints to be met.Second,to solve this problem,the mathematical support models for the flight deck,carrier aircraft entity,entity extension,entity posture,entity conflict detection,and path smoothing are established,as they provide the necessary basis for transfer path planning of the aircraft on the aircraft carrier.Third,to enable automatic transfer path planning,we design a multi-habitat parallel chaos algorithm(called KCMPSO),and use it as the optimization method for transfer path planning.Finally,we take the Kuznetsov aircraft carrier as a verification example,and conduct simulations.The simulation results show that compared with particle swarm optimization,this method can solve the transfer path planning problem for an aircraft on the aircraft carrier flight deck better.
