In this paper we discuss a novel route to chaos in cam-follower systems, a class of mechanical devices of relevance in applications. We show that a sudden transition to chaos is observed when a complete chattering mot...
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The statistical mechanics of DNA denaturation under fixed linking number is qualitatively different from that of unconstrained DNA. Quantitatively different melting scenarios are reached from two alternative assumptio...
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The statistical mechanics of DNA denaturation under fixed linking number is qualitatively different from that of unconstrained DNA. Quantitatively different melting scenarios are reached from two alternative assumptions, namely, that the denatured loops are formed at the expense of (i) overtwist or (ii) supercoils. Recent work has shown that the supercoiling mechanism results in a picture similar to Bose-Einstein condensation where a macroscopic loop appears at Tc and grows steadily with temperature, while the nature of the denatured phase for the overtwisting case has not been studied. By extending an earlier result, we show here that a macroscopic loop appears in the overtwisting scenario as well. We calculate its size as a function of temperature and show that the fraction of the total sum of microscopic loops decreases above Tc, with a cusp at the critical point.
The denaturation transition of circular DNA is studied within a Poland-Scheraga-type approach, generalized to account for the fact that the total linking number (LK), which measures the number of windings of one stran...
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The denaturation transition of circular DNA is studied within a Poland-Scheraga-type approach, generalized to account for the fact that the total linking number (LK), which measures the number of windings of one strand around the other, is conserved. In the model the LK conservation is maintained by invoking both overtwisting and writhing (supercoiling) mechanisms. This generalizes previous studies, which considered each mechanism separately. The phase diagram of the model is analyzed as a function of the temperature and the elastic constant κ associated with the overtwisting energy for any given loop entropy exponent c. As in the case where the two mechanisms apply separately, the model exhibits no denaturation transition for c≤2. For c>2 and κ=0 we find that the model exhibits a first-order transition. The transition becomes of higher order for any κ>0. We also calculate the contribution of the two mechanisms separately in maintaining the conservation of the linking number and find that it is weakly dependent on the loop exponent c.
We consider the problem of minimizing ∫ 0 ℓ √(ξ 2 +K 2 (s)ds) for a planar curve having fixed initial and final positions and directions. The total length ℓ is free. Here s is the variable of arclength parametriza...
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ISBN:
(纸本)9781467320658
We consider the problem of minimizing ∫ 0 ℓ √(ξ 2 +K 2 (s)ds) for a planar curve having fixed initial and final positions and directions. The total length ℓ is free. Here s is the variable of arclength parametrization, K(s) is the curvature of the curve and ξ >; 0 a parameter. This problem comes from a model of geometry of vision due to Petitot, Citti and Sarti. We study existence of local and global minimizers for this problem. We prove that if for a certain choice of boundary conditions there is no global minimizer, then there is neither a local minimizer nor a stationary curve (geodesic). Our main tool is the construction of the optimal synthesis for the Reed and Shepp car with quadratic cost.
We developed UAVNet, a framework for the autonomous deployment of a flying Wireless Mesh Network using small quadrocopter-based Unmanned Aerial Vehicles (UAVs). The flying wireless mesh nodes are automatically interco...
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ISBN:
(纸本)9781467349420
We developed UAVNet, a framework for the autonomous deployment of a flying Wireless Mesh Network using small quadrocopter-based Unmanned Aerial Vehicles (UAVs). The flying wireless mesh nodes are automatically interconnected to each other and building an IEEE 802.11s wireless mesh network. The implemented UAVNet prototype is able to autonomously interconnect two end systems by setting up an airborne relay, consisting of one or several flying wireless mesh nodes. The developed software includes basic functionality to control the UAVs and to setup, deploy, manage, and monitor a Wireless mesh network. Our evaluations have shown that UAVNet can significantly improve network performance.
In this paper, the qualitative properties of general nonautonomous Lotka-Volterran-species competitive systems with impulsive e？ects are studied. Some new criteria on thepermanence, extinction and global attractivity...
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In this paper, the qualitative properties of general nonautonomous Lotka-Volterran-species competitive systems with impulsive e？ects are studied. Some new criteria on thepermanence, extinction and global attractivity of partial species are established by used themethods of inequalities estimate and Liapunov functions. As applications, nonautonomous twospecies Lotka-Volterra systems with impulses are discussed.
A port container terminal is generally exploited with three types of equipments: Quay Cranes (QCs), vehicles and Yard Cranes (YCs). In this paper, we present a particular type of vehicles which is used at terminal of ...
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In plants,the patterning of root meristem requires a gradient-guided auxin maximum that depends on the concerted action of polar auxin transport,auxin biosnythesis and intracellular auxin ***,mechanisms underlying thi...
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In plants,the patterning of root meristem requires a gradient-guided auxin maximum that depends on the concerted action of polar auxin transport,auxin biosnythesis and intracellular auxin ***,mechanisms underlying this auxin gradient dependent root patterning are not fully ***,we present unexpected evidence that the activity of WUSCHEL-RELATED HOMEOBOX 5(WOX5) transcription factor modulates free auxin production in the quiescent center(QC) of the root and thus assures the maintenance of auxin maximum in the root ***,WOX5 expression is inhibited in a feedback-dependent manner by canonical auxin signaling that involves indole-3-acetic acid 17(IAA17) auxin response ***,we used loss-of-function and gain-of-function mutant analysis complemented by computer simulation study to identify and test the novel feedback mechanism that links WOX5-dependent auxin production to IAA17-mediated cellular auxin *** findings demonstrate that this feedback circuit is essential for the maintenance of auxin gradient in the root tip and the auxin-mediated root distal stem cell(DSC) differentiation.
In this work, the first target is to model and effectively resolve the Arrival Sequencing and Scheduling problem (ASS). The problem is NP-hard and exists in the Air Traffic Control (ATC) for a long time. It has been t...
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