54 research outputs found

    Stochastic Asymptotic Stabilizers for Deterministic Input-Affine Systems based on Stochastic Control Lyapunov Functions

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    In this paper, a stochastic asymptotic stabilization method is proposed for deterministic input-affine control systems, which are randomized by including Gaussian white noises in control inputs. The sufficient condition is derived for the diffucion coefficients so that there exist stochastic control Lyapunov functions for the systems. To illustrate the usefulness of the sufficient condition, the authors propose the stochastic continuous feedback law, which makes the origin of the Brockett integrator become globally asymptotically stable in probability.Comment: A preliminary version of this paper appeared in the Proceedings of the 48th Annual IEEE Conference on Decision and Control [14

    A Variational Principle for Transport Phenomena : I―Formulation of Principle

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    A new variational principle was formulated to solve the first and second kind of boundary value problems in mometum transprot, heat and mass transfer process. The variational principle formulated in this paper is based on the concept of variational invariant and is applicable to the unsteady state. By deriving Euler's equation from the functional, the equivalence between the variational principle and the boundary value problem was verified. Then, the reciprocal principle was established by verifing that the functional should be a minimum and the reciprocal functional should be a maximum at the stationary point. Finally, the parameters included in the argument functions as the generalized coordinates were defined and Lagrange-Biot's equation which determined these paramtes was derived. Some applications of this principle to the problems of the transport phenomena will be discussed in the following paper

    A Variational Principle for Transport Phenomena : II Applications to Several Problems

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    The variational principle formulated in the previous paper was applied to several problems in transport phenomena. The problems of momentum, heat and mass transfer of which exact solutions have been well known were treated and the approximate solution was obtained in order to distinguish the characteristics of the variational principle. It was indicated that the approximate solutions by the variational principle agreed with the exact solutions for the quantities related to the average values in a space or the quantities connected with the functional (flow rate, Nusselt number, Sherwood number), even when the grade of approximation for the profiles of velocities, temperature and concentration was not so good. The method described in this paper could apply to more complex problems which could not be solved exactly

    Modified Particle Swarm Optimization using Nonlinear Decreased Inertia Weight

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    Particle Swarm Optimization (PSO) has demonstrated great performance in various optimization problems. However, PSO has weaknesses, namely premature convergence and easy to get stuck or fall into local optima for complex multimodal problems. One of the causes of these weaknesses is unbalance between exploration and exploitation ability in PSO. This paper proposes a Modified Particle Swarm Optimization (MPSO) using nonlinearly decreased inertia weight called MPSO-NDW to improve the balance. The key idea of the proposed method is to control the period and decreasing rate of exploration-exploitation ability. The investigation with three famous benchmark functions shows that the accuracy, success rate, and convergence speed of the proposed MPSO-NDW is better than the common used PSO with linearly decreased inertia weight or called PSO-LDWKeywords: particle swarm optimization (PSO), premature convergence, local optima, exploration ability, exploitation ability

    PID Controller Design of Nonlinear System using a New Modified Particle Swarm Optimization with Time-Varying Constriction Coefficient

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    The proportional integral derivative (PID) controllers have been widely used in most process control systems for a long time. However, it is a very important problem how to choose PID parameters, because these parameters give a great influence on the control performance. Especially, it is difficult to tune these parameters for nonlinear systems. In this paper, a new modified particle swarm optimization (PSO) is presented to search for optimal PID parameters for such system. The proposed algorithm is to modify constriction coefficient which is nonlinearly decreased time-varying for improving the final accuracy and the convergence speed of PSO. To validate the control performance of the proposed method, a typical nonlinear system control, a continuous stirred tank reactor (CSTR) process, is illustrated. The results testify that a new modified PSO algorithm can perform well in the nonlinear PID control system design in term of lesser overshoot, rise-time, settling-time, IAE and ISE.Keywords: PID controller, Particle Swarm Optimization (PSO),constriction factor, nonlinear system

    A Novel Strategy of Dual Inhibition of Distinct Metabolic Features in Osteosarcoma

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    Mitochondria are the places for the energy production of the cells, while reactive oxygen species (ROS) are also produced alongside. In recent years, it has been reported that cancer stem cells metabolize predominantly through oxidative phosphorylation (OXPHOS) rather than glycolysis. Targeting OXPHOS achieved by suppression of ATP synthesis through mitochondrial ATP synthase could be a potential therapeutic option against cancer stem cells. Since c-Myc inhibition is considered to lead a metabolic flux to OXPHOS from glycolysis, the combinatory inhibition of both OXPHOS and glycolysis could be a strong candidate for the treatment of malignant tumors. In this chapter, we will discuss about the mitochondria metabolism as the potential therapeutic target in osteosarcoma stem cells, and the synergistic effects of combination of OXPHOS inhibitor with c-Myc inhibitor, which target both OXPHOS-dominant cancer stem cells and glycolysis-dominant non-cancer stem cells, will be discussed

    低濃度アレンドロネートはコネキシン43 活性を介して造骨系肉腫細胞株の局所浸潤能を増加させる

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    Bisphosphonates (BPs) are agents used for treating disorders of excessive bone resorption. In addition, due to their cell-killing activity, BPs were potent candidates for adjuvant cancer therapy. On the other hand, low-concentrations of BPs have been reported to increase cellular viability in several types of tumor cells. Therefore, we focused on the effect of BPs on cellular aggressiveness of malignant bone tumors at low concentrations. MTS assay was performed using osteosarcoma cell lines MG63 and HOS, fibrosarcoma cell line HT1080, and prostate cancer cell line PC3. All the cell lines showed toxicity at high concentrations. On the other hand, at lower concentrations, the cellular viabilities of HOS and MG63 were rather higher than those of untreated controls. Since this tendency was most evident, HOS was used for further assays, including cellular motility, bone resorption activity, and cathepsin K activity. The low-concentration of alendronate enhanced cellular viability and motility, which correlated with the expression of connexin 43 at the mRNA and protein levels. Interestingly, oleamide, a potent connexin 43 inhibitor, had an inhibitory effect on the enhanced proliferation. Our data suggest that alendronate may enhance the proliferation of osteoblastic cell line through connexin 43 activation.博士(医学)・乙第1296号・平成24年5月28日Copyright © 2011 Elsevier GmbH. All rights reserved

    Variable Gain Type PID Control Using PSO for Ultrasonic Motor

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    Ultrasonic motor exhibits non-linearity that relates the input (Phase difference) and output (Velocity). It also causes serious characteristic changes during operation. PID control has been widely used as the design scheme for USM. However, it is difficult for the conventional PID control to compensate such characteristic changes of the plant and non-linearity. To overcome this problem, we propose a variable gain type PID control in which PID gains are optimized using a particle swarm optimization (PSO)

    ユビキリン2は低酸素ストレスに耐性を示すことで骨肉腫の増殖を促進させる

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    Ubiquilin 2 (UBQLN2), a member of the ubiquitin-like protein family (ubiquilins), maintains protein homeostasis. Although UBQLN2 has been implicated in the pathogenesis of neurodegenerative diseases, it is also associated with mali­gnant tumors. Therefore, we examined whether UBQLN2 plays a role in human osteosarcoma. The human osteosarcoma cell line MG63 was transfected with UBQLN2 siRNA and cultured under hypoxic conditions. The rat osteosarcoma cell line COS1NR was inoculated into Fischer 344 rats, followed by injection of UBQLN2 siRNA with atelocollagen. An immunohistochemical analysis of UBQLN2 was performed using 34 cases of human high-grade osteosarcomas, and metastasis-free survival was estimated by the Kaplan-Meier method. Silencing of UBQLN2 by siRNA transfection under hypoxia led to activation of JNK and p38, resulting in induction of apoptosis in the osteosarcoma cell line MG63. Injection of UBQLN2 siRNA suppressed tumor growth in the rat osteosarcoma model, followed by apoptosis induction. The immunohistochemical examination revealed that high UBQLN2 expression was significantly associated with the unfavorable metastasis-free survival of osteosarcoma patients. UBQLN2 plays an important role in resistance to hypoxic stress and enhances tumor progression in osteosarcoma. UBQLN2 may be a new molecular target for chemotherapeutics and a useful clinicopathological marker in human osteosarcoma.博士(医学)・甲第637号・平成27年5月28日Copyright © Spandidos Publications 2015本文のリンク:http://dx.doi.org/10.3892/or.2015.378

    Synthesis of Nonlinear Model Matching Flight Control System for Tilt Rotor Aircraft

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    Abstract: In this study, we suggest a tilt rotor aircraft and attempt to apply a nonlinear model matching control method for its maneuver. The proposed method is very simple and useful to construct the control law for the complicated nonlinear system such as aircraft motion
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