We consider the stability of N-model systems that consist of two customer classes and two server pools. Servers in one of the pools can serve both classes, but those in the other pool can serve only one of the classes. The standard fluid models in general are not sufficient to establish the stability region of these systems under static priority policies. Therefore, we use a novel and a general...

Recently Ghosh (1998) reported a new regime of instability in Keplerian accretion disks which is caused by relativistic effects. This instability appears in the gas pressure dominated region when all relativistic corrections to the disk structure equations are taken into account. We show that he uses the stability criterion in completely wrong way leading to inappropriate conclusions. We perfor...

A toy model is analyzed in order to evaluate the linear stability of the gain region immediately behind a stalled accretion shock, after core bounce. This model demonstrates that a negative entropy gradient is not sufficient to warrant linear instability. The stability criterion is governed by the ratio χ of the advection time through the gain region divided by the local timescale of buoyancy. ...

We consider the problem of stability of slotted ALOHA for a system consisting of N users communicating with a common receiver, which employs spatial diversity to receive multiple transmissions simultaneously. We introduce a general packet reception model to incorporate multiple packet receptions since the collision channel model is no longer valid in such a scenario. We characterize the stabili...

Based on an extension of the Hermite-Biehler Theorem to the quasipolynomial stability problem, this paper studies the problem of stabilizing a second-order plant with dead time via a PID controller. The region in PID parameters space for the closed-loop stability is given. For a feasible proportional gain ( p k ), the region of all the admissible integral gains ( i k ) and derivative gains ( d ...

New constructive criteria of asymptotic stability of selector-linear differential inclusions are established. The wellknown absolute stability problem is also considered as a particular case of the above problem. Asymptotically stable inclusions are very similar in properties to linear stable time-invariant systems. This similarity concerns the wide range of dynamic properties. In particular, a...

We address the question of attaining stability guarantees through distributed scheduling in wireless networks. We consider a simple, local information based, distributed scheduling strategy, maximal scheduling, and prove that it attains a guaranteed fraction of the maximum stability region. By considering the notion of queue-length stability, we strengthen existing rate stability results for ma...

Various structural discontinuities, which form a discrete fracture network, play a significant role in the failure conditions and stability of the rock masses around underground excavations. Several continuum numerical methods have been used to study the stability of underground excavations in jointed rock masses but only few of them can take into account the influence of the pre-existing natur...

The Notch signalling pathway is fundamental to cell differentiation in developing and self-renewing tissues. Notch is activated upon ligand-induced conformational change of the Notch negative regulatory region (NRR), unmasking a key proteolytic site (S2) and facilitating downstream events. The favoured model requires endocytosis of a tightly bound ligand to transmit force to the NRR region, suf...

For many nonlinear control systems, the chosen equilibrium determines both the steady-state efficiency and the dynamic performance. This paper addresses the issue of obtaining an optimal equilibrium in terms of some steady-state operation criteria for a Lur’e-type system and such an equilibrium can also guarantee a sufficiently large stability region in the dynamic domain such that the system c...