256 research outputs found

    Interactive Behaviour Between the Dynamic Arrival Process of Complex Traffic Source and a Bottleneck Queue

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    This paper proposes a discrete-time heterogeneous model to represent the interaction between the dynamic arrival process of multiple TCP sources and a bottleneck queue. It utilises a novel time-variant calculation approach for transient queueing models, which modifies the conventional steady-state method by no longer requiring the equilibrium assumption. The main contributions are: (1) The limitation of the conventional queueing method is analysed and the benefits of the proposed modification is demonstrated; (2) The proposed dynamic arrival process of multiple sources is illustrated, which interacts with the queueing process and statistically responds to the positive and negative congestion feedback; (3) The fidelity of the proposed model is extensively validated by the closely matched results from MATLAB numerical solutions and NS-2 discrete-event simulation experiments

    The Fidelity Index provides a systematic quantitation of star activity of DNA restriction endonucleases

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    Restriction endonucleases are the basic tools of molecular biology. Many restriction endonucleases show relaxed sequence recognition, called star activity, as an inherent property under various digestion conditions including the optimal ones. To quantify this property we propose the concept of the Fidelity Index (FI), which is defined as the ratio of the maximum enzyme amount showing no star activity to the minimum amount needed for complete digestion at the cognate recognition site for any particular restriction endonuclease. Fidelity indices for a large number of restriction endonucleases are reported here. The effects of reaction vessel, reaction volume, incubation mode, substrate differences, reaction time, reaction temperature and additional glycerol, DMSO, ethanol and Mn2+ on the FI are also investigated. The FI provides a practical guideline for the use of restriction endonucleases and defines a fundamental property by which restriction endonucleases can be characterized

    An adaptive fuzzy control for human-in-the-loop operations with varying communication time delays

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    Time delay, especially varying time delay, is always an important factor affecting the stability to the human-in-the-loop system. Previous research usually focuses on the performance of the internal signal transmission part, but rarely considers the whole system with human and environmental factors comprehensively. For the problem, we investigate this issue by using an improved proportional-derivative-like plus damping (PD-like + d) control method, the derivative term of which is calculated based on the estimation of time delays. An embedded adaptive fuzzy logic systems (FLS)-based observer is developed to estimate and compensate for the errors caused by time delay estimations and uncertain force/ torque measuring errors. The advantages of the proposed control scheme are discussed by building an environmental input energy function and the effectiveness is also verified by the comparative simulations. The results show that under the same simulation conditions, the follower can track the leader's movements well, and the energy introduced into the environment is the same as that of the leader, which means the extra energy is dissipated to enable the object to be manipulated as desired by the leader side
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