318 research outputs found
Study on the Application of Expressway Construction Based on Sponge City Concept
Currently, in the active trial stage, sponge city concept has been applied in many low-impact development facilities on expressways in China, but many applications are not widely used. From four angles of pavement, slope, interchange and service area of expressway, this paper explains the adverse effects brought by rainwater, and then gives, and it carries out scene analysis combined with actual engineering projects with some feasible application schemes. Finally, the concept of sponge city at present is summarized, and it is considered that the optimal planning and design can be made only after establishing a reliable mathematical model and carrying out quantitative analysis
Provably learning a multi-head attention layer
The multi-head attention layer is one of the key components of the
transformer architecture that sets it apart from traditional feed-forward
models. Given a sequence length , attention matrices
, and
projection matrices , the corresponding multi-head attention layer transforms length- sequences of -dimensional
tokens via .
In this work, we initiate the study of provably learning a multi-head attention
layer from random examples and give the first nontrivial upper and lower bounds
for this problem:
- Provided satisfy certain
non-degeneracy conditions, we give a -time algorithm that learns
to small error given random labeled examples drawn uniformly from .
- We prove computational lower bounds showing that in the worst case,
exponential dependence on is unavoidable.
We focus on Boolean to mimic the discrete nature of tokens in
large language models, though our techniques naturally extend to standard
continuous settings, e.g. Gaussian. Our algorithm, which is centered around
using examples to sculpt a convex body containing the unknown parameters, is a
significant departure from existing provable algorithms for learning
feedforward networks, which predominantly exploit algebraic and rotation
invariance properties of the Gaussian distribution. In contrast, our analysis
is more flexible as it primarily relies on various upper and lower tail bounds
for the input distribution and "slices" thereof.Comment: 105 pages, comments welcom
Efficient Architecture of Variable Size HEVC 2D-DCT for FPGA Platforms
This study presents a design of two-dimensional (2D) discrete cosine transform (DCT) hardware architecture dedicated for High Efficiency Video Coding (HEVC) in field programmable gate array (FPGA) platforms. The proposed methodology efficiently proceeds 2D-DCT computation to fit internal components and characteristics of FPGA resources. A four-stage circuit architecture is developed to implement the proposed methodology. This architecture supports variable size of DCT computation, including 4×4, 8×8, 16×16, and 32×32. The proposed architecture has been implemented in System Verilog and synthesized in various FPGA platforms. Compared with existing related works in literature, this proposed architecture demonstrates significant advantages in hardware cost and performance improvement. The proposed architecture is able to sustain 4K@30fps ultra high definition (UHD) TV real-time encoding applications with a reduction of 31-64% in hardware cost
A Theoretical Analysis of NDCG Type Ranking Measures
A central problem in ranking is to design a ranking measure for evaluation of
ranking functions. In this paper we study, from a theoretical perspective, the
widely used Normalized Discounted Cumulative Gain (NDCG)-type ranking measures.
Although there are extensive empirical studies of NDCG, little is known about
its theoretical properties. We first show that, whatever the ranking function
is, the standard NDCG which adopts a logarithmic discount, converges to 1 as
the number of items to rank goes to infinity. On the first sight, this result
is very surprising. It seems to imply that NDCG cannot differentiate good and
bad ranking functions, contradicting to the empirical success of NDCG in many
applications. In order to have a deeper understanding of ranking measures in
general, we propose a notion referred to as consistent distinguishability. This
notion captures the intuition that a ranking measure should have such a
property: For every pair of substantially different ranking functions, the
ranking measure can decide which one is better in a consistent manner on almost
all datasets. We show that NDCG with logarithmic discount has consistent
distinguishability although it converges to the same limit for all ranking
functions. We next characterize the set of all feasible discount functions for
NDCG according to the concept of consistent distinguishability. Specifically we
show that whether NDCG has consistent distinguishability depends on how fast
the discount decays, and 1/r is a critical point. We then turn to the cut-off
version of NDCG, i.e., NDCG@k. We analyze the distinguishability of NDCG@k for
various choices of k and the discount functions. Experimental results on real
Web search datasets agree well with the theory.Comment: COLT 201
Study on coalescence dynamics of unequal-sized microbubbles captive on solid substrate
The dynamics of bubble coalescence are of importance for a number of industrial processes, in which the size inequality of the parent bubbles plays a significant role in mass transport, topological change and overall motion. In this study, coalescence of unequal-sized microbubbles captive on a solid substrate was observed from cross-section view using synchrotron high-speed imaging technique and a microfluidic gas generation device. The bridging neck growth and surface wave propagation at the early stage of coalescence were investigated by experimental and numerical methods. The results show that theoretical half-power-law of neck growth rate is still valid when viscous effect is neglected. However, the inertial-capillary time scale is associated with the initial radius of the smaller parent microbubble. The surface wave propagation rate on the larger parent microbubble is proportional to the inertial-capillary time scale
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