294 research outputs found
Low complexity hardware oriented H.264/AVC motion estimation algorithm and related low power and low cost architecture design
制度:新 ; 報告番号:甲2999号 ; 学位の種類:博士(工学) ; 授与年月日:2010/3/15 ; 早大学位記番号:新525
China’s E-commerce Development Path and Mode Innovation of Agricultural Product Based on Business Model Canvas Method
Rapid development of modern e-commerce technology has greatly improved the efficiency of China’s agricultural product supply chain operation , and the traditional e-commerce of agricultural products mode and path have been far from enough to solve new problems that modern economic development brought in China. This paper synthesizes the domestic and foreign development status of e-commerce of agricultural products, further establishes the analysis frame of e-commerce of agricultural products mode, first applies the business model canvas method to generalize China’s e-commerce mode of agricultural products from nine important dimensions of customer segmentation, key business, value proposition, core resources etc, aiming at the deficiencies of the present model,creatively put forward new mode, LBS O2O Community with WeChat, and explores development path of the community e-commerce of agricultural products, provides feasible suggestions to agricultural operators in the selection and optimization of electronic business mode
Numerical Methods for Pricing a Guaranteed Minimum Withdrawal Benefit (GMWB) as a Singular Control Problem
Guaranteed Minimum Withdrawal Benefits(GMWB) have become popular riders on variable annuities. The pricing of a GMWB contract was originally formulated as a singular stochastic control problem which results in a Hamilton Jacobi Bellman (HJB) Variational Inequality (VI). A penalty method method can then be used to solve the HJB VI. We present a rigorous proof of convergence of the penalty method to the viscosity solution of the HJB VI assuming the underlying asset follows a Geometric Brownian Motion. A direct control method is an alternative formulation for the HJB VI. We also extend the HJB VI to the case of where the underlying asset follows a Poisson jump diffusion.
The HJB VI is normally solved numerically by an implicit method, which gives rise to highly nonlinear discretized algebraic equations. The classic policy iteration approach works well for the Geometric Brownian Motion case. However it is not efficient in some circumstances such as when the underlying asset follows a Poisson jump diffusion process. We develop a combined fixed point policy iteration scheme which significantly increases the efficiency of solving the discretized equations. Sufficient conditions to ensure the convergence of the combined fixed point policy iteration scheme are derived both for the penalty method and direct control method.
The GMWB formulated as a singular control problem has a special structure which results in a block matrix fixed point policy iteration converging about one order of magnitude faster than a full matrix fixed point policy iteration. Sufficient conditions for convergence of the block matrix fixed point policy iteration are derived. Estimates for bounds on the penalty parameter (penalty method) and scaling parameter (direct control method) are obtained so that convergence of the iteration can be expected in the presence of round-off error
Excimer Laser and Femtosecond Laser in Ophthalmology
Laser technology is used in many basic and clinical disciplines and specialties, and it has played an important role in promoting the development of ophthalmology, especially corneal refractive surgery. We provide an overview of the evolution of laser technology for use in refractive and other ophthalmologic surgeries, mainly focusing on two types of lasers and their applications. First, we discuss the characteristics of the excimer laser and its application in corneal refractive surgery treating ametropia (e.g., photorefractive keratectomy (PRK), laser epithelial keratomileusis (LASEK), epipolis laser in situ keratomileusis (Epi-LASIK), and transepithelial photorefractive keratectomy (Trans-PRK) and presbyopia surgery). Second, we discuss the characteristics of the femtosecond laser and its application in corneal refractive surgery (e.g., femtosecond laser in situ keratomileusis (FS-LASIK), insertion of intracorneal ring segments, small-incision lenticule extraction (SMILE), and femtosecond lenticule extraction (FLEx)) and other ophthalmologic surgeries (e.g., penetrating keratoplasty (PKP), deep anterior lamellar keratoplasty, Descemet’s stripping endothelial keratoplasty (DSEK), and cataract surgery). The patients studied received many benefits from the excimer laser and femtosecond laser technologies and were satisfied with their clinical outcomes
Guiding Corpus-based Set Expansion by Auxiliary Sets Generation and Co-Expansion
Given a small set of seed entities (e.g., ``USA'', ``Russia''), corpus-based
set expansion is to induce an extensive set of entities which share the same
semantic class (Country in this example) from a given corpus. Set expansion
benefits a wide range of downstream applications in knowledge discovery, such
as web search, taxonomy construction, and query suggestion. Existing
corpus-based set expansion algorithms typically bootstrap the given seeds by
incorporating lexical patterns and distributional similarity. However, due to
no negative sets provided explicitly, these methods suffer from semantic drift
caused by expanding the seed set freely without guidance. We propose a new
framework, Set-CoExpan, that automatically generates auxiliary sets as negative
sets that are closely related to the target set of user's interest, and then
performs multiple sets co-expansion that extracts discriminative features by
comparing target set with auxiliary sets, to form multiple cohesive sets that
are distinctive from one another, thus resolving the semantic drift issue. In
this paper we demonstrate that by generating auxiliary sets, we can guide the
expansion process of target set to avoid touching those ambiguous areas around
the border with auxiliary sets, and we show that Set-CoExpan outperforms strong
baseline methods significantly.Comment: WWW 202
MoViT: Memorizing Vision Transformers for Medical Image Analysis
The synergy of long-range dependencies from transformers and local
representations of image content from convolutional neural networks (CNNs) has
led to advanced architectures and increased performance for various medical
image analysis tasks due to their complementary benefits. However, compared
with CNNs, transformers require considerably more training data, due to a
larger number of parameters and an absence of inductive bias. The need for
increasingly large datasets continues to be problematic, particularly in the
context of medical imaging, where both annotation efforts and data protection
result in limited data availability. In this work, inspired by the human
decision-making process of correlating new ``evidence'' with previously
memorized ``experience'', we propose a Memorizing Vision Transformer (MoViT) to
alleviate the need for large-scale datasets to successfully train and deploy
transformer-based architectures. MoViT leverages an external memory structure
to cache history attention snapshots during the training stage. To prevent
overfitting, we incorporate an innovative memory update scheme, attention
temporal moving average, to update the stored external memories with the
historical moving average. For inference speedup, we design a prototypical
attention learning method to distill the external memory into smaller
representative subsets. We evaluate our method on a public histology image
dataset and an in-house MRI dataset, demonstrating that MoViT applied to varied
medical image analysis tasks, can outperform vanilla transformer models across
varied data regimes, especially in cases where only a small amount of annotated
data is available. More importantly, MoViT can reach a competitive performance
of ViT with only 3.0% of the training data
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