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作者:Li, Feng;Cho, Richard W.;Buhl, Lauren Kaye;等   学位:

学位授予时间:2025

培养单位: 导师:

Li, Feng;Cho, Richard W.;Buhl, Lauren Kaye;等

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Synaptic plasticity is a fundamental feature of the nervous system that allows adaptation to changing behavioral environments. Most studies of synaptic plasticity have examined the regulated trafficking of postsynaptic glutamate receptors that generates alterations in synaptic transmission. Whether and how changes in the presynaptic release machinery contribute to neuronal plasticity is less clear. The SNARE complex mediates neurotransmitter release in response to presynaptic Ca[superscript 2+] entry. Here we show that the SNARE fusion clamp Complexin undergoes activity-dependent phosphorylation that alters the basic properties of neurotransmission in Drosophila. Retrograde signaling following stimulation activates PKA-dependent phosphorylation of the Complexin Cterminus that selectively and transiently enhances spontaneous release. Enhanced spontaneous release is required for activity-dependent synaptic growth. These data indicate that SNAREdependent fusion mechanisms can be regulated in an activity-dependent manner and highlight the key role of spontaneous neurotransmitter release as a mediator of functional and structural plasticity.

作者:Steele, Stephanie C., Triantafyllou, Michael S, Weymouth, Gabriel D   学位:

学位授予时间:2017

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Steele, Stephanie C., Triantafyllou, Michael S, Weymouth, Gabriel D

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Dynamic shape change of the octopus mantle during fast jet escape manoeuvres results in added mass energy recovery to the energetic advantage of the octopus, giving escape thrust and speed additional to that due to jetting alone. We show through numerical simulations and experimental validation of overall wake behaviour, that the success of the energy recovery is highly dependent on shrinking speed and Reynolds number, with secondary dependence on shape considerations and shrinking amplitude. The added mass energy recovery ratio η[subscript ma], which measures momentum recovery in relation to the maximum momentum recovery possible in an ideal flow, increases with increasing the non-dimensional shrinking parameter σ[superscript ∗]=ȧ[subscript max]/U√(Re[subscript 0]), where ȧ[subscript max] is the maximum shrinking speed, U is the characteristic flow velocity and √(Re0) is the Reynolds number at the beginning of the shrinking motion. An estimated threshold σ[superscript ∗]≈10 determines whether or not enough energy is recovered to the body to produce net thrust. Since there is a region of high transition for 10<σ[superscript ∗]<30 where the recovery performance varies widely and for σ[superscript ∗]>100 added mass energy is recovered at diminishing returns, we propose a design criterion for shrinking bodies to be in the range of 50<σ[superscript ∗]<100, resulting in 61–82 % energy recovery.

作者:Baros, Stefanos, Ilić, Marija D.   学位:

学位授予时间:2017

培养单位: 导师:

Baros, Stefanos, Ilić, Marija D.

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In this work, we propose a distributed control methodology that solves the problem of dispatching and regulating the power outputs of a group of deloaded wind Double- Fed Induction Generators (DFIGs) so that wind farm (WF) power output regulation is attained. Our control methodology guarantees additionally that fair load-sharing among the DFIGs is achieved. In our context, fair load-sharing means that, the ratio defined by the mechanical power over the maximum power from the wind i.e the utilization level, of all DFIGs, is the same in steady state. Dynamic, distributed dispatch and control of the power outputs of DFIGs refers to their ability to self-dispatch and regulate their power outputs under dynamical conditions and through peer-to-peer information exchange. Initially, we propose a leader-follower consensus protocol that DFIGs can adopt into their control system to attain: a) asymptotic consensus on their utilization levels (i.e fair load-sharing), b) total power output regulation. Then, we perform compositional stability analysis of the protocol and design a distributed Control Lyapunov Function (CLF) - based torque controller for the rotor-side converter (RSC) that realizes the protocol. Finally, the performance of our proposed distributed control methodology is evaluated through simulations on the modified IEEE 24-bus RT system.

作者:Baros, Stefanos, Ilić, Marija D.   学位:

学位授予时间:2017

培养单位: 导师:

Baros, Stefanos, Ilić, Marija D.

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Today the state-of-the-art (SoA) wind generators (WGs) are the double-fed induction (DFIGs) with integrated storage devices. In the future, these WGs are expected to be one of the largest producers of renewable energy worldwide. In this paper, we propose a distributed control methodology for solving the problem of coordinating and controlling a group of SoA WGs to attain fast wind farm (WF) power output regulation with each storage device providing the same amount of power, i.e with equal sharing among the storage devices. Our proposed methodology introduces a consensus protocol for coordinating the grid-side converters (GSCs), whose dynamical equations constitute their closed-loop dynamics, and a particular closed-loop form for the interfacing capacitor dynamics. We establish stability of these closed-loop dynamics by leveraging singular perturbation and Lyapunov theories, proving that with these closed-loop dynamics DFIGs accomplish their assigned control objectives. Finally, we analytically construct a distributed and a Control Lyapunov Function (CLF) -based control law for the GSC and the DCDC converter respectively, which jointly lead to the desired closed-loop dynamics. We demonstrate the effectiveness of our methodology through simulations on the IEEE 24-bus reliability test system (RTS).

5 Georama of Trash [学位论文]

作者:Ghosn, Rania, Jazairy, El Hadi   学位:

学位授予时间:2017

培养单位: 导师:

Ghosn, Rania, Jazairy, El Hadi

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In its material dimension, the land receives both the positive and negative externalities of human life. Trash, for instance, is a negative externality that also reaches the ground, but that is conveniently placed ;;out of sight’. This project by Design Earth, however, proposes an opposite strategy: in a society that only reacts to fetishistic spectacularization, perhaps it is not unreasonable to think of projects that transform the trash into an architectural spectacle.

作者:Meng, Zi Yang;Liu, Junwei;Qi, Yang;等   学位:

学位授予时间:2017

培养单位: 导师:

Meng, Zi Yang;Liu, Junwei;Qi, Yang;等

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Monte Carlo simulation is an unbiased numerical tool for studying classical and quantum many-body systems. One of its bottlenecks is the lack of a general and efficient update algorithm for large size systems close to the phase transition, for which local updates perform badly. In this Rapid Communication, we propose a general-purpose Monte Carlo method, dubbed self-learning Monte Carlo (SLMC), in which an efficient update algorithm is first learned from the training data generated in trial simulations and then used to speed up the actual simulation. We demonstrate the efficiency of SLMC in a spin model at the phase transition point, achieving a 10–20 times speedup.