Aircraft selection modeling: a multi-step heuristic to enumerate airlift alternatives

Annals of Operations Research - We consider the use of the new C-130J-30 aircraft for long distance (strategic) cargo movement. Currently, only large aircraft, the C-5 and the C-17, are identified...     

Compatible Poisson brackets for Lax equations and classical ζ -matrices

We construct a family of compatible linear Poisson brackets for Lax equations and equations of zero curvature with a spectral parameter.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 164, pp. 176–188, 1987.     

A network of priority queues in heavy traffic: One bottleneck station

In this paper we consider an open queueing network having multiple classes, priorities, and general service time distributions. In the case where there is a single bottleneck station we conjecture that normalized queue length and sojourn time processes converge, in the heavy traffic limit, to one-dimensional reflected Brownian motion, and present expressions for its drift and variance. The conjecture is motivated by known heavy traffic limit theorems for some special cases of the general model, and some conjectured “Heavy Traffic Principles” derived from them. Using the known stationary distribution of one-dimensional reflected Brownian motion, we present expressions for the heavy traffic limit of stationary queue length and sojourn time distributions and moments. For systems with Markov routing we are able to explicitly calculate the limits.     

Extensions of Gauge groups,related to quantum anomalies

An infinite-dimensional central extension of the group of currents is constructed, related to the anomaly in the Gauss law, discovered by L. D. Faddeev.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 146, pp. 102–118, 1985.     

A critically loaded multirate link with trunk reservation

We consider a loss system model of interest in telecommunications. There is a single service facility with N servers and no waiting room. There are K types of customers, with type ί customers requiring A _ί servers simultaneously. Arrival processes are Poisson and service times are exponential. An arriving type ί customer is accepted only if there are Rί(⩾A_ί ) idle servers. We examine the asymptotic behavior of the above system in the regime known as critical loading where both N and the offered load are large and almost equal. We also assume that R ₁,..., R _K-1 remain bounded, while R _K ^N ←∞ and R _K ^N /√N ← 0 as N ← ∞. Our main result is that the K dimensional “queue length” process converges, under the appropriate normalization, to a particular K dimensional diffusion. We show that a related system with preemption has the same limit process. For the associated optimization problem where accepted customers pay, we show that our trunk reservation policy is asymptotically optimal when the parameters satisfy a certain relation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Interplay of Antiferromagnetic Coupling and Spin Crossover in Dinuclear Iron(II) Complexes

This article reports on the study of the interplay between magnetic coupling and spin transition in 2,2′-bipyrimidine (bpym)-bridged iron(II) dinuclear compounds. Coexistence of both phenomena has been observed in [Fe(bpym)(NCS)₂]₂bpym, [Fe(bpym)(NCSe)₂]₂bpym and [Fe(bt)(NCS)₂]₂bpym (bpym = 2,2′-bipyrimidine, bt = 2,2′-bithiazoline) by the action of external physical factors namely pressure or electromagnetic radiation. Competition between magnetic exchange and spin crossover has been studied in [Fe(bpym)(NCS)₂]₂bpym at 6.3 kbar. LIESST experiments carried out in [Fe(bpym)(NCSe)₂]₂bpym and [Fe(bt)(NCS)₂]₂bpym at 4.2 K have shown that is possible to achieve dinuclear molecules with different spin states in this class of compounds. This revised version was published online in August 2006 with corrections to the Cover Date.