An investigation of dynamic instability of stiffened rectangular plates

Boundaries of regions of parametric instability of simply supported stiffened rectangular plat

An investigation of the parametric resonance of rectangular plates reinforced with closely spaced stiffeners

Parametric resonance and structural stability model of uniformly reinforced flat plate

Exponential Bounds for Queues with Markovian Arrivals

Exponential bounds P[queue ≥ b] ≤ φe^(-γb) are found for queues whose increments are described by Markovian Additive Processes. This is done application of maximal inequalities to exponential martingales for such processes. Through a thermodynamic approach the constant γ is shown to be the decay rate for an asymptotic lower bound for the queue length distribution. The class of arrival processes considered includes a wide variety of Markovian multiplexer models, and a general treatment of these is given, along with that of Markov modulated arrivals. Particular attention is paid to the calculation of the prefactor φ

Local Correlation Functions for Mean-field Dynamical Semigroups on C*algebras

This paper concerns the dynamics of local correlation functions in dissipative mean-field systems. We extend the abstract notion of a mean-field dynamical semigroup on a C*-algebra given in [1], from an evolution on site-averaged observables, to one on a class of local observables. Conditions are established under which this generalized mean-field dynamics factorises, in the thermodynamic limit, into contributions from disjoint regions. Correspondingly, the nested correlation functions factorise into contributions for single site observables in this limit. We demonstrate that these conditions are satisfied for a large class of model systems

Rigorous Bounds for Loss Probabilities in Multiplexers of Discrete Heterogenous Markovian Sources

Exponential upper bounds of the form P[queue ≥ b] ≤ φy^(-b) are obtained for the distribution of the queue length in a model of a multiplexer in which the input is a heterogeneous superposition of discrete Markovian on-off sources. These bounds are valid at all queue lengths, rather than just asymptotic in the limit b→∞. The decay constant y is found by numerical solution of a single transcendental equation which determines the effective bandwidths of the sources in the limit b→∞. The prefactor φ is given explicitly in terms of y. The bound provides a means to determine rigorous corrections to effective bandwidths for multiplexers with finite buffers

Factoring out the parallelism effect in ellipsis: An interactional approach?

Traditionally, there have been three standard assumptions made about the Parallelism Effect on VP-ellipsis, namely that the effect is categorical, that it applies asymmetrically and that it is uniquely due to syntactic factors. Based on the results of a series of experiments involving online and offline tasks, it will be argued that the Parallelism Effect is instead noncategorical and interactional. The factors investigated include construction type, conceptual and morpho-syntactic recoverability, finiteness and anaphor type (to test VP-anaphora). The results show that parallelism is gradient rather than categorical, effects both VP-ellipsis and anaphora, and is influenced by both structural and non-structural factors

ON THE STRUCTURE AND ACQUISITION OF TELICITY AND UNACCUSATIVITY IN VIETNAMESE

In this paper, we investigate Chinese L2 learners' knowledge of two grammatical constraints in Vietnamese: the first, a constraint on the aspectual interpretation of accomplishment predicates, the second pertaining to alternations in the position of embedded subjects in mono-clausal lam causatives. Whereas the former constraint is shared by Vietnamese and Chinese, the two languages differ with respect to the latter. The results of three judgment tasks provide statistically reliable support for the idea that L2 interlanguage grammars are not ultimately limited by Ll patterns; given the absence of explicit teaching and only limited exposure to relevant structures, it is suggested that learners' performance may be guided by UG information

Exponential Upper Bounds via Martingales for Multiplexers with Markovian Arrivals.

We obtain explicit upper bounds in closed form for the queue length in a slotted time FCFS queue in which the service requirement is a sum of independent Markov processes on the state space {O, 1}, with integral service rate. The bound is of the form P[queue length ≥ b] ≤ cy^(-b) for any b ≥ 1 where c 1 are given explicitly in terms of the parameters of the model. The model can be viewed as an approximation for the burst-level component of the queue in an ATM multiplexer. We obtain heavy traffic bounds for the mean queue length and show that for typical parameters this far exceeds the mean queue length for independent arrivals at the same load. We compare our results on the mean queue length with an analytic expression for the case of unit service rate, and compare our results on the full distribution with computer simulations

Large deviations and overflow probabilities for the general single-server queue, with applications

We consider from a thermodynamic viewpoint queueing systems where the workload process is assumed to have an associated large deviation principle with arbitrary scaling: there exist increasing scaling functions (a_t, v_t, t ϵ R_+) and a rate function I such that if (W_t, t ϵ R_+) denotes the workload process, then lim_(t→∞) (v_t)^(-1)logP(W_t/a_t > w) = -I(w) on the continuity set of I. In the case that a_t = v_t = t it has been argued heuristically, and recently proved in a fairly general context (for discrete time models) by Glynn and Whitt [8], that the queue-length distribution (that is, the distribution of supremum of the workload process Q = sup_(t≥0) W_t) decays exponentially: P(Q > b) ~ e^(-δb) and the decay rate δ is directly related to the rate function I. We establish conditions for a more general result to hold, where the scaling functions are not necessarily linear in t: we find that the queue-length distribution has an exponential tail only if lim_(t→∞) a_t/v_t is finite and strictly positive; otherwise, provided our conditions are satisfied, the tail probabilities decay like P(Q > b) ~ e^(-δv(a^(-1)(b))). We apply our results to a range of workload processes, including fractional Brownian motion (a model that has been proposed in the literature (see, for example, Leland et al [10] and Norros [13]) to account for self-similarity and long range dependence) and, more generally, Gaussian processes with stationary increments. We also show that the martingale upper bound estimates obtained by Daley and Duffield [5], when the workload is modelled as an Ornstein-Uhlenbeck position process, are asymptotically correct

Patient transfers in Australia: Implications for nursing workload and patient outcomes

Aim To discuss the impact of patient transfers on patient outcomes and nursing workload. Background Many patient transfers are essential and occur in response to patients' clinical changes. However, increasingly within Australia transfers are performed in response to reductions in bed numbers, resulting in 'bed block'. Evaluation A discussion of the literature related to inpatient transfers, nursing workload and patient safety. Key issues Measures to increase patient flow such as short-stay units may result in an increase in patient transfers and nursing workload. Frequent patient transfers may also increase the risk of medication incidents, health-care acquired infections and patient falls. Conclusions The continuing demand for health care has led to a reactionary bed management system that, in an attempt to accommodate patients, has resulted in increased transfers between wards. This can have a negative effect on nursing workload and affect patient outcomes. Implications for nursing management High nursing workload is cited as one reason for nurses leaving the profession. Reductions in non-essential transfers may reduce nurse workload, improve patient outcomes and enhance continuity of patient care. © 2011 Blackwell Publishing Ltd