1,588 research outputs found
Collaborative Feature Learning from Social Media
Image feature representation plays an essential role in image recognition and
related tasks. The current state-of-the-art feature learning paradigm is
supervised learning from labeled data. However, this paradigm requires
large-scale category labels, which limits its applicability to domains where
labels are hard to obtain. In this paper, we propose a new data-driven feature
learning paradigm which does not rely on category labels. Instead, we learn
from user behavior data collected on social media. Concretely, we use the image
relationship discovered in the latent space from the user behavior data to
guide the image feature learning. We collect a large-scale image and user
behavior dataset from Behance.net. The dataset consists of 1.9 million images
and over 300 million view records from 1.9 million users. We validate our
feature learning paradigm on this dataset and find that the learned feature
significantly outperforms the state-of-the-art image features in learning
better image similarities. We also show that the learned feature performs
competitively on various recognition benchmarks
Building a St\"uckelberg Portal
We construct explicit string theory models realizing the recently proposed
"St\"uckelberg Portal" scenario, a framework for building Z' mediation models
without the need to introduce unwanted exotic matter charged under the Standard
Model. This scenario can be viewed purely field-theoretically, although it is
particularly well motivated from string theory. By analyzing carefully the
St\"uckelberg couplings between the Abelian gauge bosons and the RR axions, we
construct the first global intersecting brane models which extend the Standard
Model with a genuine hidden sector, to which it is nonetheless connected via
U(1) mass mixings. Utilizing the explicit models we construct, we discuss some
broad phenomenological properties and experimental implications of this
scenario such as Z-Z' mixings, dark matter stability and relic density, and
supersymmetry mediation. With an appropriate confining hidden sector, our setup
also provides a minimal realization of the hidden valley scenario. We further
explore the possibility of obtaining small Z' masses from a large ensemble of
U(1) bosons. Related to the St\"uckelberg portal are two mechanisms that
connect the visible and the hidden sectors, namely mediation by
non-perturbative operators and the hidden photon scenario, on which we briefly
comment.Comment: 39 pages, 11 figure
Changer: Feature Interaction is What You Need for Change Detection
Change detection is an important tool for long-term earth observation
missions. It takes bi-temporal images as input and predicts "where" the change
has occurred. Different from other dense prediction tasks, a meaningful
consideration for change detection is the interaction between bi-temporal
features. With this motivation, in this paper we propose a novel general change
detection architecture, MetaChanger, which includes a series of alternative
interaction layers in the feature extractor. To verify the effectiveness of
MetaChanger, we propose two derived models, ChangerAD and ChangerEx with simple
interaction strategies: Aggregation-Distribution (AD) and "exchange". AD is
abstracted from some complex interaction methods, and "exchange" is a
completely parameter\&computation-free operation by exchanging bi-temporal
features. In addition, for better alignment of bi-temporal features, we propose
a flow dual-alignment fusion (FDAF) module which allows interactive alignment
and feature fusion. Crucially, we observe Changer series models achieve
competitive performance on different scale change detection datasets. Further,
our proposed ChangerAD and ChangerEx could serve as a starting baseline for
future MetaChanger design.Comment: 11 pages, 5 figure
Measurement and Analysis of Bilateral Costs between China and Trading Partners Based on the Revised Gravity Model
Abstract A revised gravity model has been adopted in the thesis to measure the changes of bilateral trade costs of China and other 28 countries during 1992~ 2007.The results are as follows: China’s trade costs take on a declining trendand the bilateral trade costs between China and developed countries is lower than that of developing countries. As the trade costs between China and major trading partners take on a declining trend, which even has room for further decline, the major policy significances in this thesis are that China shall continue to excavate the way to reduce the trade costs in order tofurther enhance the export competitiveness
Distributed Multi-authority Attribute-based Encryption Scheme for Friend Discovery in Mobile Social Networks
AbstractIn recent years, the rapid expansion of the capability of portable devices, cloud servers and cellular network technologies is the wind beneath the wing of mobile social networks. Compared to traditional web-based online social networks, the mobile social networks can assist users to easily discover and make new social interaction with others. A challenging task is to protect the privacy of the users’ profiles and communications. Existing works are mainly based on traditional cryptographic methods, such as homomorphic and group signatures, which are very computationally costly. In this paper, we propose a novel distributed multi-authority attribute-based encryption scheme to efficiently achieve privacy-preserving without additional special signatures. In addition, the proposed scheme can achieve fine-grained and flexible access control. Detailed analysis demonstrates the effectiveness and practicability of our scheme
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