4,273 research outputs found
Current rectification by asymmetric molecules: An ab initio study
We study current rectification effect in an asymmetric molecule
HOOC-CH-(CH) sandwiched between two Aluminum electrodes using
an {\sl ab initio} nonequilibrium Green function method. The conductance of the
system decreases exponentially with the increasing number of CH. The
phenomenon of current rectification is observed such that a very small current
appears at negative bias and a sharp negative differential resistance at a
critical positive bias when . The rectification effect arises from the
asymmetric structure of the molecule and the molecule-electrode couplings. A
significant rectification ratio of 38 can be achieved when .Comment: to appear in J. Chem. Phy
Steady State of Pedestrian Flow in Bottleneck Experiments
Experiments with pedestrians could depend strongly on initial conditions.
Comparisons of the results of such experiments require to distinguish carefully
between transient state and steady state. In this work, a feasible algorithm -
Cumulative Sum Control Chart - is proposed and improved to automatically detect
steady states from density and speed time series of bottleneck experiments. The
threshold of the detection parameter in the algorithm is calibrated using an
autoregressive model. Comparing the detected steady states with previous
manually selected ones, the modified algorithm gives more reproducible results.
For the applications, three groups of bottleneck experiments are analysed and
the steady states are detected. The study about pedestrian flow shows that the
difference between the flows in all states and in steady state mainly depends
on the ratio of pedestrian number to bottleneck width. When the ratio is higher
than a critical value (approximately 115 persons/m), the flow in all states is
almost identical with the flow in steady state. Thus we have more possibilities
to compare the flows from different experiments, especially when the detection
of steady states is difficult.Comment: 19 pages, 7 figure
Medical Image Contrast Enhancement via Wavelet Homomorphic Filtering Transform
A novel enhancement algorithm for magnetic resonance (MR) images based on spatial homomorphic filtering transform is proposed in this paper. By this method, the source image is decomposed into different sub-images by dyadic wavelet transform. Homomorphic filtering functions are applied in performing filtering of corresponding sub-band images to attenuate the low frequencies as well as amplify the high frequencies, and a linear adjustment is carried out on the low frequency of the highest level. Later, inverse dyadic wavelet transform is applied to reconstruct the object image. Experiment results on MR images illustrate that the proposed method can eliminate non-uniformity luminance distribution effectively, some subtle tissues can be improved effectually, and some weak sections have not been smoothed by the novel method.
Distinctive action sketch for human action recognition
Recent developments in the field of computer vision have led to a renewed interest in sketch correlated research. There have emerged considerable solid evidence which revealed the significance of sketch. However, there have been few profound discussions on sketch based action analysis so far. In this paper, we propose an approach to discover the most distinctive sketches for action recognition. The action sketches should satisfy two characteristics: sketchability and objectiveness. Primitive sketches are prepared according to the structured forests based fast edge detection. Meanwhile, we take advantage of Faster R-CNN to detect the persons in parallel. On completion of the two stages, the process of distinctive action sketch mining is carried out. After that, we present four kinds of sketch pooling methods to get a uniform representation for action videos. The experimental results show that the proposed method achieves impressive performance against several compared methods on two public datasets.The work was supported in part by the National Science Foundation of China (61472103, 61772158, 61702136, and 61701273) and Australian Research Council (ARC) grant (DP150104645)
Static and spherically symmetric black holes in gravity with a background Kalb-Ramond field
The Lorentz symmetry of gravity is spontaneously broken when the
non-minimally coupled Kalb-Ramond field acquires a nonzero vacuum expectation
value. In this work, we present exact solutions for static and spherically
symmetric black holes in the framework of this Lorentz-violating gravity
theory. In order to explore the physical implications of Lorentz violation, we
analyze the thermodynamic properties of the obtained solutions and evaluate its
impact on some classical gravitational experiments within the Solar System.
Furthermore, the Lorentz-violating parameter is constrained by using the
measured results of these experiments.Comment: 21 pages and 1 figur
Cirrhosis Classification Based on Texture Classification of Random Features
Accurate staging of hepatic cirrhosis is important in investigating the cause and slowing down the effects of cirrhosis. Computer-aided diagnosis (CAD) can provide doctors with an alternative second opinion and assist them to make a specific treatment with accurate cirrhosis stage. MRI has many advantages, including high resolution for soft tissue, no radiation, and multiparameters imaging modalities. So in this paper, multisequences MRIs, including T1-weighted, T2-weighted, arterial, portal venous, and equilibrium phase, are applied. However, CAD does not meet the clinical needs of cirrhosis and few researchers are concerned with it at present. Cirrhosis is characterized by the presence of widespread fibrosis and regenerative nodules in the hepatic, leading to different texture patterns of different stages. So, extracting texture feature is the primary task. Compared with typical gray level cooccurrence matrix (GLCM) features, texture classification from random features provides an effective way, and we adopt it and propose CCTCRF for triple classification (normal, early, and middle and advanced stage). CCTCRF does not need strong assumptions except the sparse character of image, contains sufficient texture information, includes concise and effective process, and makes case decision with high accuracy. Experimental results also illustrate the satisfying performance and they are also compared with typical NN with GLCM
Simulation and Experimental Analyses on Quasi-Static and Dynamic Performances of Four-Star Cellular Structure
A novel four-star cellular structure (FSCS) is proposed. Firstly, relative density of FSCS, regular octagons and regular hexagons are obtained accordingly. Then, their in-plane quasi-static and dynamic performances are conducted under the premise of equal number of cells, equal mass and equal relative density by adopting Hyperworks and Ls-Dyna software. Macroscopic deformation processes indicate that FSCS, regular octagons and regular hexagons are presented as "compression-shrinkage" negative Poisson\u27s ratio deformation mode, "V" deformation mode and "X" deformation mode, respectively. Subsequently, size effects of unit cell are carried out, and as the number of cell layers reaches no less than 9, platform stress of FSCS gradually tends to be stable. To verify the accuracy of finite element (FE) simulation models, quasi-static compression test is executed on three-dimensional FSCS. The results indicate that FE simulation results agree well with experimental predictions, and the proposed FSCS is equipped with superior energy absorption capability
PCDNF: Revisiting Learning-based Point Cloud Denoising via Joint Normal Filtering
Recovering high quality surfaces from noisy point clouds, known as point
cloud denoising, is a fundamental yet challenging problem in geometry
processing. Most of the existing methods either directly denoise the noisy
input or filter raw normals followed by updating point positions. Motivated by
the essential interplay between point cloud denoising and normal filtering, we
revisit point cloud denoising from a multitask perspective, and propose an
end-to-end network, named PCDNF, to denoise point clouds via joint normal
filtering. In particular, we introduce an auxiliary normal filtering task to
help the overall network remove noise more effectively while preserving
geometric features more accurately. In addition to the overall architecture,
our network has two novel modules. On one hand, to improve noise removal
performance, we design a shape-aware selector to construct the latent tangent
space representation of the specific point by comprehensively considering the
learned point and normal features and geometry priors. On the other hand, point
features are more suitable for describing geometric details, and normal
features are more conducive for representing geometric structures (e.g., sharp
edges and corners). Combining point and normal features allows us to overcome
their weaknesses. Thus, we design a feature refinement module to fuse point and
normal features for better recovering geometric information. Extensive
evaluations, comparisons, and ablation studies demonstrate that the proposed
method outperforms state-of-the-arts for both point cloud denoising and normal
filtering
Use acupuncture to relieve perimenopausal syndrome: study protocol of a randomized controlled trial
Law Number 11 / 2008 on Information and Electronic Transaction (UU ITE) is the regulation concerning on criminal law in addition to the Criminal Code (KUHP). UU ITE is commonly regarded additional regulation of the Criminal Code as a special law (lex specialis) in which Penal Code is deemed as lex generalis. It is based on the principle of lex specialis derogate legi generalis. This article uses legal research to review the decision of District Court in Bandung Number 1033/PID.B/2014/PN.BDG where it comprises legislation and cases. It concludes that the judge is not frugal in applying the principle lex specialis derogat legi generalis in the consideration. This is associated with the indictment of public prosecutor which only prejudges with article 303 paragraph (1) to 2. In contrast, the indictment which does not meet the requirement of a careful, clear, and complete description asserts to become void by law.
Keywords: Online Gambling, Criminal Principle, Indictmen
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