169 research outputs found
Short-Term Forecasting of Passenger Demand under On-Demand Ride Services: A Spatio-Temporal Deep Learning Approach
Short-term passenger demand forecasting is of great importance to the
on-demand ride service platform, which can incentivize vacant cars moving from
over-supply regions to over-demand regions. The spatial dependences, temporal
dependences, and exogenous dependences need to be considered simultaneously,
however, which makes short-term passenger demand forecasting challenging. We
propose a novel deep learning (DL) approach, named the fusion convolutional
long short-term memory network (FCL-Net), to address these three dependences
within one end-to-end learning architecture. The model is stacked and fused by
multiple convolutional long short-term memory (LSTM) layers, standard LSTM
layers, and convolutional layers. The fusion of convolutional techniques and
the LSTM network enables the proposed DL approach to better capture the
spatio-temporal characteristics and correlations of explanatory variables. A
tailored spatially aggregated random forest is employed to rank the importance
of the explanatory variables. The ranking is then used for feature selection.
The proposed DL approach is applied to the short-term forecasting of passenger
demand under an on-demand ride service platform in Hangzhou, China.
Experimental results, validated on real-world data provided by DiDi Chuxing,
show that the FCL-Net achieves better predictive performance than traditional
approaches including both classical time-series prediction models and neural
network based algorithms (e.g., artificial neural network and LSTM). This paper
is one of the first DL studies to forecast the short-term passenger demand of
an on-demand ride service platform by examining the spatio-temporal
correlations.Comment: 39 pages, 10 figure
Jamming Transition of Point-to-Point Traffic Through Cooperative Mechanisms
We study the jamming transition of two-dimensional point-to-point traffic
through cooperative mechanisms using computer simulation. We propose two
decentralized cooperative mechanisms which are incorporated into the
point-to-point traffic models: stepping aside (CM-SA) and choosing alternative
routes (CM-CAR). Incorporating CM-SA is to prevent a type of ping-pong jumps
from happening when two objects standing face-to-face want to move in opposite
directions. Incorporating CM-CAR is to handle the conflict when more than one
object competes for the same point in parallel update. We investigate and
compare four models mainly from fundamental diagrams, jam patterns and the
distribution of cooperation probability. It is found that although it decreases
the average velocity a little, the CM-SA increases the critical density and the
average flow. Despite increasing the average velocity, the CM-CAR decreases the
average flow by creating substantially vacant areas inside jam clusters. We
investigate the jam patterns of four models carefully and explain this result
qualitatively. In addition, we discuss the advantage and applicability of
decentralized cooperation modeling.Comment: 17 pages, 14 figure
Quantifying traffic emission reductions and traffic congestion alleviation from high-capacity ride-sharing
Despite the promising benefits that ride-sharing offers, there has been a
lack of research on the benefits of high-capacity ride-sharing services. Prior
research has also overlooked the relationship between traffic volume and the
degree of traffic congestion and emissions. To address these gaps, this study
develops an open-source agent-based simulation platform and a heuristic
algorithm to quantify the benefits of high-capacity ride-sharing with
significantly lower computational costs. The simulation platform integrates a
traffic emission model and a speed-density traffic flow model to characterize
the interactions between traffic congestion levels and emissions. The
experiment results demonstrate that ride-sharing with vehicle capacities of 2,
4, and 6 passengers can alleviate total traffic congestion by approximately 3%,
4%, and 5%, and reduce traffic emissions of a ride-sourcing system by
approximately 30%, 45%, and 50%, respectively. This study can guide
transportation network companies in designing and managing more efficient and
environment-friendly mobility systems
Subband image coding using filter banks with non-uniform passband distribution
In this paper, subband filter banks with non-uniform passband distribution in frequency domain are studied. Several design examples are presented and compared with conventional uniform bandwidth filter banks. Image coding results show that filter banks with non-uniform bandwidth outperform filter banks with uniform bandwidth, especially in low bit rate coding.published_or_final_versio
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Eradication of unresectable liver metastasis through induction of tumour specific energy depletion.
Treatment of liver metastasis experiences slow progress owing to the severe side effects. In this study, we demonstrate a strategy capable of eliminating metastatic cancer cells in a selective manner. Nucleus-targeting W18O49 nanoparticles (WONPs) are conjugated to mitochondria-selective mesoporous silica nanoparticles (MSNs) containing photosensitizer (Ce6) through a Cathepsin B-cleavable peptide. In hepatocytes, upon the laser irradiation, the generated singlet oxygen species are consumed by WONPs, in turn leading to the loss of their photothermally heating capacity, thereby sparing hepatocyte from thermal damage induced by the laser illumination. By contrast, in cancer cells, the cleaved peptide linker allows WONPs and MSNs to respectively target nucleus and mitochondria, where the therapeutic powers could be unleashed, both photodynamically and photothermally. This ensures the energy production of cancer cells can be abolished. We further assess the underlying molecular mechanism at both gene and protein levels to better understand the therapeutic outcome
Chemiluminescent Nanomicelles for Imaging Hydrogen Peroxide and Self-Therapy in Photodynamic Therapy
Hydrogen peroxide is a signal molecule of the tumor, and its overproduction makes a higher concentration in tumor tissue compared to normal tissue. Based on the fact that peroxalates can make chemiluminescence with a high efficiency in the presence of hydrogen peroxide, we developed nanomicelles composed of peroxalate ester oligomers and fluorescent dyes, called peroxalate nanomicelles (POMs), which could image hydrogen peroxide with high sensitivity and stability. The potential application of the POMs in photodynamic therapy (PDT) for cancer was also investigated. It was found that the PDT-drug-loaded POMs were sensitive to hydrogen peroxide, and the PDT drug could be stimulated by the chemiluminescence from the reaction between POMs and hydrogen peroxide, which carried on a self-therapy of the tumor without the additional laser light resource
Nuclei micro-array FISH, a desirable alternative for MCL diagnosis
Mantle cell lymphoma (MCL) is a rare, specific lymphoma subtype. Though the morphologic and immunophenotypic features of MCL have been well described in recent literatures, it is still a diagnostic dilemma because of its frequent confusion with other small B cell lymphomas (SBCLs). In the present study, we primarily focus on establishing a sensitive and specific method for the diagnosis of MCL, which is efficient to distinguish this disease from other SBCLs. We carried out our investigation for MCL and other SBCLs (including SLL, FL, MZL, and MALT) on their feature of morphology, immunophenotype, and t(11;14)(q13;q32) translocation analysis based on polymerase chain reaction (PCR) and interphase nuclei micro-array fluorescence in situ hybridization (FISH). The morphologic and immunologic analysis showed the positive rate of cyclin D1 was 76.47% in MCL, which was significantly higher than that in other SBCLs. The positive rate of t(11;14) translocation was 25.81% and 35.48%, respectively, tested by general and semi-nested PCR, while 93.10% positive rate was shown with low background and strong signals pattern when tested by Nuclei micro-array FISH. Our research shows that t(11;14) translocation is a special and useful diagnostic marker for MCL, and detection of the marker by nuclei micro-array FISH is convenient and economic, especially more sensitive and specific than other methods for the diagnosis of MCL
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