714 research outputs found
Reverse-Safe Data Structures for Text Indexing
We introduce the notion of reverse-safe data structures. These are data structures that prevent the reconstruction of the data they encode (i.e., they cannot be easily reversed). A data structure D is called z-reverse-safe when there exist at least z datasets with the same set of answers as the ones stored by D. The main challenge is to ensure that D stores as many answers to useful queries as possible, is constructed efficiently, and has size close to the size of the original dataset it encodes. Given a text of length n and an integer z, we propose an algorithm which constructs a z-reverse-safe data structure that has size O(n) and answers pattern matching queries of length at most d optimally, where d is maximal for any such z-reverse-safe data structure. The construction algorithm takes O(n ω log d) time, where ω is the matrix multiplication exponent. We show that, despite the n ω factor, our engineered implementation takes only a few minutes to finish for million-letter texts. We further show that plugging our method in data analysis applications gives insignificant or no data utility loss. Finally, we show how our technique can be extended to support applications under a realistic adversary model
Recommended from our members
A China – US Bilateral Investment Treaty: A Template for a Multilateral Framework for Investment?
A bilateral investment treaty between China and the US would not only be of importance for the economic relations of the world's two largest economies, but could also become a template for a multilateral framework for investment. This Perspective looks at key outstanding issues in the China-US negotiations and identifies alternative compromises
Distributed Contingency Analysis over Wide Area Network among Dispatch Centers
Traditionally, a regional dispatch center uses the equivalent method to deal
with external grids, which fails to reflect the interactions among regions.
This paper proposes a distributed N-1 contingency analysis (DCA) solution,
where dispatch centers join a coordinated computation using their private data
and computing resources. A distributed screening method is presented to
determine the Critical Contingency Set (DCCS) in DCA. Then, the distributed
power flow is formulated as a set of boundary equations, which is solved by a
Jacobi-Free Newton-GMRES (JFNG) method. During solving the distributed power
flow, only boundary conditions are exchanged. Acceleration techniques are also
introduced, including reusing preconditioners and optimal resource scheduling
during parallel processing of multiple contingencies. The proposed method is
implemented on a real EMS platform, where tests using the Southwest Regional
Grid of China are carried out to validate its feasibility.Comment: 5 pages, 6 figures, 2017 IEEE PES General Meetin
Attention Loss Adjusted Prioritized Experience Replay
Prioritized Experience Replay (PER) is a technical means of deep
reinforcement learning by selecting experience samples with more knowledge
quantity to improve the training rate of neural network. However, the
non-uniform sampling used in PER inevitably shifts the state-action space
distribution and brings the estimation error of Q-value function. In this
paper, an Attention Loss Adjusted Prioritized (ALAP) Experience Replay
algorithm is proposed, which integrates the improved Self-Attention network
with Double-Sampling mechanism to fit the hyperparameter that can regulate the
importance sampling weights to eliminate the estimation error caused by PER. In
order to verify the effectiveness and generality of the algorithm, the ALAP is
tested with value-function based, policy-gradient based and multi-agent
reinforcement learning algorithms in OPENAI gym, and comparison studies verify
the advantage and efficiency of the proposed training framework
Investigation on the static fatigue mechanism and effect of specimen thickness on the static fatigue lifetime in WC–Co cemented carbides
The static fatigue mechanism and effect of specimen thickness on static fatigue lifetime for four WC–Co cemented carbides were studied with different binder contents and carbide grain sizes. Static fatigue tests under three-point bend loading were conducted on different sized specimens. The fracture surfaces of rupture specimens were examined by scanning electron microscopy to investigate the static fatigue micromechanisms.Досліджено механізм статичної втоми і вплив товщини зразка на термін служби при статичній втомі для чотирьох твердих сплавів WC–Co з різним вмістом зв’язки і розміром зерен. Випробування на статичну втому при навантаженні за схемою триточкового вигину було проведено на зразках різних розмірів. Поверхні зламів зруйнованих зразків було вивчено c допомогою скануючої електронної мікроскопії з метою дослідження мікромеханізму статичної втоми.Исследованы механизм статической усталости и влияние толщины образца на срок службы при статической усталости для четырех твердых сплавов WC–Co с различным содержанием связующего и размером зерен. Испытания на статическую усталость при нагрузке по схеме трехточечного изгиба были проведены на образцах различных размеров. Поверхности изломов разрушенных образцов были изучены c помощью сканирующей электронной микроскопии с целью исследования микромеханизмов статической усталости
On a problem of Henning and Yeo about the transversal number of uniform linear systems whose 2-packing number is fixed
For , let be an -uniform linear system. The
transversal number of is the minimum
number of points that intersect every line of . The 2-packing
number of is the maximum number of
lines such that the intersection of any three of them is empty. In [Discrete
Math. 313 (2013), 959--966] Henning and Yeo posed the following question: Is it
true that if is a -uniform linear system then
holds for
all ?. In this paper, some results about of -uniform linear systems
whose 2-packing number is fixed which satisfies the inequality are given
MicroRNA-451 suppresses tumor cell growth by down-regulating IL6R gene expression
The miR-451 was found to be frequently down-regulated in tumors, indicating that miR-451 could play an important role in carcinogenesis. This study uncovered the mechanism by which the miR-451 functions as a tumor suppressor. The target genes of miR-451 were determined using target gene prediction softwares. Then the miR-451 mimics were introduced into RKO and Hela cells respectively. The proliferation and invasion of cells were monitored by MTT, cell cycle and in vitro extracellular matrix invasion assays. Also the angiogenesis of HUVEC cells transfected with miR-451 mimics was examined. Subsequently, IL6R, a predicted target gene of miR-451, was studied by real time PCR, Western blotting, and siRNA technologies. The mRNA and protein levels of IL6R gene were found to be down-regulated in the RKO and Hela cells transfected with miR-451 mimics. Consequently, the cell proliferation was inhibited. Also, the invasion of RKO cells was suppressed. Furthermore, the angiogenesis of HUVEC cells transfected with miR-451 mimics was assayed and the decreased angiogenic ability was detected compared to the controls. All these results were validated by IL6R siRNA experiments. The IL6R gene is a target gene of miR-451. The miR-451 behaves as a tumor suppressor, probably by targeting the IL6R pathway.This project was supported by the Huazhong University of Science and Technology (2010MS034 and HF-09-37-2011-510).Ritrýnt tímaritPeer Reviewe
- …