Simulation study of stepwise relaxation in a spheromak plasma

The energy relaxation process of a spheromak plasma in a flux conserver is investigated by means of a three-dimensional magnetohydrodynamic simulation. The resistive decay of an initial force-free profile brings the spheromak plasma to an m=1/n=2 ideal kink unstable region. It is found that the energy relaxation takes place in two steps; namely, the relaxation consists of two physically distinguished phases, and there exists an intermediate phase in between, during which the relaxation becomes inactive temporarily. The first relaxation corresponds to the transition from an axially symmetric force-free state to a helically symmetric one with an n=2 crescent magnetic island structure via the helical kink instability. The n=2 helical structure is nonlinearly sustained in the intermediate phase. The helical twisting of the flux tube creates a reconnection current in the vicinity of the geometrical axis. The second relaxation is triggered by the rapid growth of the n=1 mode when the reconnection current exceeds a critical value. The helical twisting relaxes through magnetic reconnection toward an axially symmetric force-free state. It is also found that the poloidal flux reduces during the helical twisting in the first relaxation and the generation of the toroidal flux occurs through the magnetic reconnection process in the second relaxation

Design and implementation of hiding method for file manipulation of essential services by system call proxy using virtual machine monitor

Security or system management software is essential for keeping systems secure. To deter attacks on essential services, hiding information related to essential services is helpful. This paper describes the design, the implementation, and the evaluation of a method to make files invisible to all services except their corresponding essential services and provides access methods to those files in a virtual machine (VM). In the proposed method, the virtual machine monitor (VMM) monitors the system call, which invoked by an essential process to access essential files, and requests proxy execution to the proxy process on another VM. The VMM returns the result and skips the execution of the original system call on the protection target VM. Thus, access to essential files by the essential service is skipped on the protection target VM, but the essential service can access the file content

Memory Access Monitoring and Disguising of Process Information to Avoid Attacks to Essential Services

To prevent attacks on essential software and to mitigate damage, an attack avoiding method that complicates process identification from attackers is proposed. This method complicates the identification of essential services by replacing process information with dummy information. However, this method allows attackers to identify essential processes by detecting changes in process information. To address this problems and provide more complexity to process identification, this paper proposes a memory access monitoring by using a virtual machine monitor. By manipulating the page access permission, a virtual machine monitor detects page access, which includes process information, and replaces it with dummy information. This paper presents the design, implementation, and evaluation of the proposed method

A Classical Technique to Prove the h-Cobordism Theorem

Let W be a compact and smooth manifold, whose dimension greater than 5, with boundary components V and V\u27. Suppose that W, V, and V\u27 are all simply connected, and the homology group of the pair (W, V) is trivial. The h-Cobordism Theorem States that W is diffeomorphic to a product cobordism. In this paper we will follow a classical technique developed by John Milnor in his \u22Lectures on the h-Cobordism Theorems\u22 half a century ago

Evaluation and design of function for tracing diffusion of classified information for file operations with KVM

Cases of classified information leakage have become increasingly common. To address this problem, we have developed a function for tracing the diffusion of classified information within an operating system. However, this function suffers from the following two problems: first, in order to introduce the function, the operating system's source code must be modified. Second, there is a risk that the function will be disabled when the operating system is attacked. Thus, we have designed a function for tracing the diffusion of classified information in a guest operating system by using a virtual machine monitor. By using a virtual machine monitor, we can introduce the proposed function in various environments without modifying the operating system's source code. In addition, attacks aimed at the proposed function are made more difficult, because the virtual machine monitor is isolated from the operating system. In this paper, we describe the implementation of the proposed function for file operations and child process creation in the guest operating system with a kernel-based virtual machine. Further, we demonstrate the traceability of diffusing classified information by file operations and child process creation. We also report the logical lines of code required to introduce the proposed function and performance overheads