149 research outputs found
A finite element method for time fractional partial differential equations
This is the authors' PDF version of an article published in Fractional calculus and applied analysis© 2011. The original publication is available at www.springerlink.comThis article considers the finite element method for time fractional differential equations
On the Feasibility of Social Network-based Pollution Sensing in ITSs
Intense vehicular traffic is recognized as a global societal problem, with a
multifaceted influence on the quality of life of a person. Intelligent
Transportation Systems (ITS) can play an important role in combating such
problem, decreasing pollution levels and, consequently, their negative effects.
One of the goals of ITSs, in fact, is that of controlling traffic flows,
measuring traffic states, providing vehicles with routes that globally pursue
low pollution conditions. How such systems measure and enforce given traffic
states has been at the center of multiple research efforts in the past few
years. Although many different solutions have been proposed, very limited
effort has been devoted to exploring the potential of social network analysis
in such context. Social networks, in general, provide direct feedback from
people and, as such, potentially very valuable information. A post that tells,
for example, how a person feels about pollution at a given time in a given
location, could be put to good use by an environment aware ITS aiming at
minimizing contaminant emissions in residential areas. This work verifies the
feasibility of using pollution related social network feeds into ITS
operations. In particular, it concentrates on understanding how reliable such
information is, producing an analysis that confronts over 1,500,000 posts and
pollution data obtained from on-the- field sensors over a one-year span.Comment: 10 pages, 15 figures, Transaction Forma
Curriculum Proximal Policy Optimization with Stage-Decaying Clipping for Self-Driving at Unsignalized Intersections
Unsignalized intersections are typically considered as one of the most
representative and challenging scenarios for self-driving vehicles. To tackle
autonomous driving problems in such scenarios, this paper proposes a curriculum
proximal policy optimization (CPPO) framework with stage-decaying clipping. By
adjusting the clipping parameter during different stages of training through
proximal policy optimization (PPO), the vehicle can first rapidly search for an
approximate optimal policy or its neighborhood with a large parameter, and then
converges to the optimal policy with a small one. Particularly, the stage-based
curriculum learning technology is incorporated into the proposed framework to
improve the generalization performance and further accelerate the training
process. Moreover, the reward function is specially designed in view of
different curriculum settings. A series of comparative experiments are
conducted in intersection-crossing scenarios with bi-lane carriageways to
verify the effectiveness of the proposed CPPO method. The results show that the
proposed approach demonstrates better adaptiveness to different dynamic and
complex environments, as well as faster training speed over baseline methods.Comment: 7 pages, 4 figure
Shape-Aware Fine-Grained Classification of Erythroid Cells
Fine-grained classification and counting of bone marrow erythroid cells are
vital for evaluating the health status and formulating therapeutic schedules
for leukemia or hematopathy. Due to the subtle visual differences between
different types of erythroid cells, it is challenging to apply existing
image-based deep learning models for fine-grained erythroid cell
classification. Moreover, there is no large open-source datasets on erythroid
cells to support the model training. In this paper, we introduce BMEC (Bone
Morrow Erythroid Cells), the first large fine-grained image dataset of
erythroid cells, to facilitate more deep learning research on erythroid cells.
BMEC contains 5,666 images of individual erythroid cells, each of which is
extracted from the bone marrow erythroid cell smears and professionally
annotated to one of the four types of erythroid cells. To distinguish the
erythroid cells, one key indicator is the cell shape which is closely related
to the cell growth and maturation. Therefore, we design a novel shape-aware
image classification network for fine-grained erythroid cell classification.
The shape feature is extracted from the shape mask image and aggregated to the
raw image feature with a shape attention module. With the shape-attended image
feature, our network achieved superior classification performance (81.12\%
top-1 accuracy) on the BMEC dataset comparing to the baseline methods. Ablation
studies also demonstrate the effectiveness of incorporating the shape
information for the fine-grained cell classification. To further verify the
generalizability of our method, we tested our network on two additional public
white blood cells (WBC) datasets and the results show our shape-aware method
can generally outperform recent state-of-the-art works on classifying the WBC.
The code and BMEC dataset can be found on https://github.com/wangye8899/BMEC
Stability of a numerical method for a fractional telegraph equation
In this paper, we introduce a numerical method for solving the time-space fractional telegraph equations. The numerical method is based on a quadrature formula approach and a stability condition for the numerical method is obtained. Two numerical examples are given and the stability regions are plotted
The Spatially Resolved Properties of the GW170817 Host Galaxy
GW170817 is the unique gravitational-wave (GW) event that is associated to
the electromagnetic (EM) counterpart GRB 170817A. NGC 4993 is identified as the
host galaxy of GW170817/GRB 170817A. In this paper, we particularly focus on
the spatially resolved properties of NGC 4993. We present the photometric
results from the comprehensive data analysis of the high spatial-resolution
images in the different optical bands. The morphological analysis reveals that
NGC 4993 is a typical early-type galaxy without significant remnants of major
galaxy merger. The spatially resolved stellar population properties of NGC 4993
suggest that the galaxy center has passive evolution with the outskirt formed
by gas accretion. We derive the merging rate of the compact object per galaxy
by a co-evolution scenario of supermassive black hole and its host galaxy. If
the galaxy formation is at redshift 1.0, the merging rate per galaxy is
to within the merging decay time from
1.0 to 5.0 Gyr. The results provide the vital information for the ongoing GW EM
counterpart detections. The HST data analysis presented in this paper can be
also applied for the Chinese Space Station Telescope (CSST) research in the
future.Comment: RAA accepte
Thermomechanical property of rice kernels studied by DMA
The thermomechanical property of the rice kernels was investigated using a dynamic mechanical analyzer (DMA). The length change of rice kernels with a loaded constant force along the major axis direction was detected during temperature scanning. The thermomechanical transition occurred in rice kernels when heated. The transition temperatures were determined as 47°C, 50°C and 56°C for the medium-grain rice with the moisture contents of 18.1%, 16.0% and 12.5% (wet basis), respectively. Length change of the rice kernels increased with the increase of the temperature and moisture content. Among the four rice varieties investigated, the results showed that the thermomechanical property was not significantly affected by variety
Numerical analysis of a two-parameter fractional telegraph equation
In this paper we consider the two-parameter fractional telegraph equation of the form
-\, ^CD_{t_0^+}^{\alpha+1} u(t,x) + \, ^CD_{x_0^+}^{\beta+1} u (t,x)- \, ^CD_{t_0^+}^{\alpha}u (t,x)-u(t,x)=0. Here
\, ^CD_{t_0^+}^{\alpha}, \, ^CD_{t_0^+}^{\alpha+1}, \, ^CD_{x_0^+}^{\beta+1} are
operators of the Caputo-type
fractional derivative, where and . The existence
and uniqueness of the equations are proved by using the Banach
fixed point theorem. A numerical method is introduced to solve this
fractional telegraph equation and stability conditions for the numerical
method are obtained. Numerical examples are given in the final section of the
paper
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