We characterize the distance-regular Ivanov–Ivanov–Faradjev graph from the spectrum, and construct cospectral graphs of the Johnson graphs, Doubled Odd graphs, Grassmann graphs, Doubled Grassmann graphs, antipodal covers of complete bipartite graphs, and many of the Taylor graphs. We survey the known results on cospectral graphs of the Hamming graphs, and of all distance-regular graphs on at mo...

There has been considerable discussion surrounding the barriers to spectrum sharing in the literature. Among those is the `trust gap' that exists, according to the PCAST report. Trust is a complex human construct that signi cantly includes risk. In this paper, we examine the risks faced by the di erent user classes proposed by the FCC for sharing in the 3.5 GHz band. We argue that the invisible...

We present a simple method to improve the performance of turbo codes. Distance spectrum analysis is used to identify information bit positions aaected by low-distance error events, which are few in number due to the sparseness of the spectrum. A modiied encoder inserts dummy bits in these positions, resulting in a lower and steeper error oor in the bit-error-rate (BER) performance curve. For su...

The notion of distance-regularity for undirected graphs can be extended for the directed case in two different ways. Damerell adopted the strongest definition of distanceregularity, which is equivalent to say that the corresponding set of distance matrices {Ai}i=0 constitutes a commutative association scheme. In particular, a (strongly) distance-regular digraph Γ is stable, which means that Ai ...

We theoretically and experimentally study the phenomena related to self-phase modulation of Airy pulses in fibers. During nonlinear evolution, most spectral components of the Airy pulses concentrate into one or two peaks for normal and anomalous dispersion, respectively. The resulting peaks self-shift along the propagation, effectively mapping the longitudinal coordinate into the frequency doma...

The multigrams allow us to split a string of symbols into a stream of variable length sequences. The direct application of this method to vector-quantized speech spectra fails, we develop an extension of the method called modiied multi-grams or multigrams with distance. The algorithm for mod-iied multigram dictionary training as well as experimental results are presented. We found a signiicant ...

Distance adaptive spectrum allocation exploits the tradeoff between spectrum width and reach to improve resource utilization by tailoring the modulation format to the level of impairments along the path. We first show that the the distanceadaptive routing and spectrum assignment (DA-RSA) problem in mesh networks is a special case of a multiprocessor scheduling problem. We then develop a suite o...

The effects of stimulus frequency and bandwidth on distance perception were examined for nearby sources in simulated reverberant space. Sources to the side [containing reverberation-related cues and interaural level difference (ILD) cues] and to the front (without ILDs) were simulated. Listeners judged the distance of noise bursts presented at a randomly roving level from simulated distances ra...

The Hawking effect can be rederived in terms of two-point functions and in such a way that it makes it possible to estimate, within the conventional semiclassical theory, the contribution of ultrashort distances to the Planckian spectrum. For Schwarzschild black holes of three solar masses the analysis shows that Hawking radiation is very robust up to frequencies of 96TH or 270TH for bosons and...