155 research outputs found
Bid Shading in The Brave New World of First-Price Auctions
Online auctions play a central role in online advertising, and are one of the
main reasons for the industry's scalability and growth. With great changes in
how auctions are being organized, such as changing the second- to first-price
auction type, advertisers and demand platforms are compelled to adapt to a new
volatile environment. Bid shading is a known technique for preventing
overpaying in auction systems that can help maintain the strategy equilibrium
in first-price auctions, tackling one of its greatest drawbacks. In this study,
we propose a machine learning approach of modeling optimal bid shading for
non-censored online first-price ad auctions. We clearly motivate the approach
and extensively evaluate it in both offline and online settings on a major
demand side platform. The results demonstrate the superiority and robustness of
the new approach as compared to the existing approaches across a range of
performance metrics.Comment: In Proceedings of the 29th ACM International Conference on
Information and Knowledge Management (CIKM'20), October 19-23, 2020, Virtual
Event, Irelan
AutoAttention: Automatic Field Pair Selection for Attention in User Behavior Modeling
In Click-through rate (CTR) prediction models, a user's interest is usually
represented as a fixed-length vector based on her history behaviors. Recently,
several methods are proposed to learn an attentive weight for each user
behavior and conduct weighted sum pooling. However, these methods only manually
select several fields from the target item side as the query to interact with
the behaviors, neglecting the other target item fields, as well as user and
context fields. Directly including all these fields in the attention may
introduce noise and deteriorate the performance. In this paper, we propose a
novel model named AutoAttention, which includes all item/user/context side
fields as the query, and assigns a learnable weight for each field pair between
behavior fields and query fields. Pruning on these field pairs via these
learnable weights lead to automatic field pair selection, so as to identify and
remove noisy field pairs. Though including more fields, the computation cost of
AutoAttention is still low due to using a simple attention function and field
pair selection. Extensive experiments on the public dataset and Tencent's
production dataset demonstrate the effectiveness of the proposed approach.Comment: Accepted by ICDM 202
SNR-based adaptive acquisition method for fast Fourier ptychographic microscopy
Fourier ptychographic microscopy (FPM) is a computational imaging technique
with both high resolution and large field-of-view. However, the effective
numerical aperture (NA) achievable with a typical LED panel is ambiguous and
usually relies on the repeated tests of different illumination NAs. The imaging
quality of each raw image usually depends on the visual assessments, which is
subjective and inaccurate especially for those dark field images. Moreover, the
acquisition process is really time-consuming.In this paper, we propose a
SNR-based adaptive acquisition method for quantitative evaluation and adaptive
collection of each raw image according to the signal-to-noise ration (SNR)
value, to improve the FPM's acquisition efficiency and automatically obtain the
maximum achievable NA, reducing the time of collection, storage and subsequent
calculation. The widely used EPRY-FPM algorithm is applied without adding any
algorithm complexity and computational burden. The performance has been
demonstrated in both USAF targets and biological samples with different imaging
sensors respectively, which have either Poisson or Gaussian noises model.
Further combined with the sparse LEDs strategy, the number of collection images
can be shorten to around 25 frames while the former needs 361 images, the
reduction ratio can reach over 90%. This method will make FPM more practical
and automatic, and can also be used in different configurations of FPM.Comment: 11 pages, 6 figure
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