Yoshiharu Maeno

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Experts of chance discovery have recognized a new class of problems where the previous methods fail to visualize a latent structure behind observation. There are invisible events that play an important role in the dynamics of visible events. An invisible leader in a communication network is a typical example. Such an event is named a dark event. A novel(More)
Consolidated server systems using server virtualization involves serious risks of host server failures that induce unexpected downs of all hosted virtual machines and applications. To protect applications requiring high-availability from unpredictable host server failures, redundant configuration using virtual machines can be an effective countermeasure.(More)
This paper presents a high-availability solution to a virtualized data center which consists of a cluster of physical servers and hosted virtual machines (VMs). VMs are typically generated through software called virtual machine monitor (VMM) running on physical servers. Both VMs and VMMs face the risks of software aging which are caused by aging-related(More)
Fault tree analysis (FTA) is a traditional reliability analysis technique. In practice, the manual development of fault trees could be costly and error-prone, especially in the case of fault tolerant systems due to the inherent complexities such as various dependencies and interactions among components. Some dynamic fault tree gates, such as Functional(More)
In this paper, I present a method to solve a node discovery problem in a networked organization. Covert nodes refer to the nodes which are not observable directly. They affect social interactions, but do not appear in the surveillance logs which record the participants of the social interactions. Discovering the covert nodes is defined as identifying the(More)
Comprehensive analytic model for system availability analysis often confronts the largeness issue where a system designer cannot easily handle the model and the solution is not given in a feasible solution time. Hierarchical decomposition of a large state-space model gives a promising solution to the largeness issue when the model is decomposable. However,(More)
This paper addresses a method to analyze the covert social network foundation hidden behind the terrorism disaster. It is to solve a node discovery problem, which means to discover a node, which functions relevantly in a social network, but escaped from monitoring on the presence and mutual relationship of nodes. The method aims at integrating the expert(More)