182,835 research outputs found
Algorithms for Learning Sparse Additive Models with Interactions in High Dimensions
A function is a Sparse Additive
Model (SPAM), if it is of the form where , . Assuming 's, to be unknown, there exists extensive work
for estimating from its samples. In this work, we consider a generalized
version of SPAMs, that also allows for the presence of a sparse number of
second order interaction terms. For some , with , the function is now assumed to be of the form:
. Assuming we have the
freedom to query anywhere in its domain, we derive efficient algorithms
that provably recover with finite sample bounds.
Our analysis covers the noiseless setting where exact samples of are
obtained, and also extends to the noisy setting where the queries are corrupted
with noise. For the noisy setting in particular, we consider two noise models
namely: i.i.d Gaussian noise and arbitrary but bounded noise. Our main methods
for identification of essentially rely on estimation of sparse
Hessian matrices, for which we provide two novel compressed sensing based
schemes. Once are known, we show how the
individual components , can be estimated via
additional queries of , with uniform error bounds. Lastly, we provide
simulation results on synthetic data that validate our theoretical findings.Comment: To appear in Information and Inference: A Journal of the IMA. Made
following changes after review process: (a) Corrected typos throughout the
text. (b) Corrected choice of sampling distribution in Section 5, see eqs.
(5.2), (5.3). (c) More detailed comparison with existing work in Section 8.
(d) Added Section B in appendix on roots of cubic equatio
Fast design optimization of UWB antenna with WLAN Band-Notch
In this paper, a methodology for rapid design optimization of an ultra-wideband ( UWB) monopole antenna with a lower WLAN band-notch is presented. The band-notch is realized using an open loop resonator implemented in the radiation patch of the antenna. Design optimization is a two stage process, with the first stage focused on the design of the antenna itself, and the second stage aiming at identification of the appropriate dimensions of the resonator with the purpose of allocating the band-notch in the desired frequency range. Both optimization stages are realized using surrogate-based optimization involving variable-fidelity electromagnetic ( EM) simulation models as well as an additive response correction ( first stage), and sequential approximate optimization ( second stage). The final antenna design is obtained at the CPU cost corresponding to only 23 high-fidelity EM antenna simulations
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