3,525,449 research outputs found

    Construction of Minimax Control for Almost Conservative Controlled Dynamic Systems with the Limited Perturbations

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    The problem is considered for constructing a minimax control for a linear stationary controlled dynamical almost conservative system (a conservative system with a weakly perturbed coefficient matrix) on which an unknown perturbation with bounded energy acts.To find the solution of the Riccati equation, an approach is proposed according to which the matrix-solution is represented as a series expansion in a small parameter and the unknown components of this matrix are determined from an infinite system of matrix equations.A necessary condition for the existence of a solution of the Riccati equation is formulated, as well as theorems on additive operations on definite parametric matrices. A condition is derived for estimating the parameter appearing in the Riccati equation.An example of a solution of the minimax control problem for a gyroscopic system is given. The system of differential equations, which describes the motion of a rotor rotating at a constant angular velocity, is chosen as the basis

    Engineering Heteromaterials to Control Lithium Ion Transport Pathways.

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    Safe and efficient operation of lithium ion batteries requires precisely directed flow of lithium ions and electrons to control the first directional volume changes in anode and cathode materials. Understanding and controlling the lithium ion transport in battery electrodes becomes crucial to the design of high performance and durable batteries. Recent work revealed that the chemical potential barriers encountered at the surfaces of heteromaterials play an important role in directing lithium ion transport at nanoscale. Here, we utilize in situ transmission electron microscopy to demonstrate that we can switch lithiation pathways from radial to axial to grain-by-grain lithiation through the systematic creation of heteromaterial combinations in the Si-Ge nanowire system. Our systematic studies show that engineered materials at nanoscale can overcome the intrinsic orientation-dependent lithiation, and open new pathways to aid in the development of compact, safe, and efficient batteries

    Ground-state Stabilization of Open Quantum Systems by Dissipation

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    Control by dissipation, or environment engineering, constitutes an important methodology within quantum coherent control which was proposed to improve the robustness and scalability of quantum control systems. The system-environment coupling, often considered to be detrimental to quantum coherence, also provides the means to steer the system to desired states. This paper aims to develop the theory for engineering of the dissipation, based on a ground-state Lyapunov stability analysis of open quantum systems via a Heisenberg-picture approach. Algebraic conditions concerning the ground-state stability and scalability of quantum systems are obtained. In particular, Lyapunov stability conditions expressed as operator inequalities allow a purely algebraic treatment of the environment engineering problem, which facilitates the integration of quantum components into a large-scale quantum system and draws an explicit connection to the classical theory of vector Lyapunov functions and decomposition-aggregation methods for control of complex systems. The implications of the results in relation to dissipative quantum computing and state engineering are also discussed in this paper.Comment: 18 pages, to appear in Automatic

    V-Model Role Engineering

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    The paper focuses on role engineering which is an important topic in the development of access control system, particularly when considering Role Based Access Control – RBAC models. Despite the wide use of RBAC in various applications, the role engineering process is not a standardized approach. The paper aims to define a methodology and a process model for role engineeringInformation security, access control systems, role based access control systems – RBAC, engineering methodologies, security policies, access control models

    A six degrees of freedom MEMS manipulator

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    This thesis reports about a six degrees of freedom (DOF) precision manipulator in MEMS, concerning concept generation for the manipulator followed by design and fabrication (of parts) of the proposed manipulation concept in MEMS. Researching the abilities of 6 DOF precision manipulation in MEMS is part of the Multi Axes Micro Stage (MAMS) project in which the disciplines of precision engineering, control engineering and micro mechanical engineering are represented
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