1,485 research outputs found

    Driver distraction detection using experimental methods and machine learning algorithms.

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    Driver distraction causes numerous road accidents, which is approximately equal to 25% of the total crashes according to the reports by the National Highway Traffic Safety Administration. Warnings can be helpful to mitigate the risks caused by driver distraction. Previous studies on driver distraction detection have not sufficiently found relevant input features to filter insignificant information, thus limiting the improvement of efficiency. Moreover, the disadvantages of driving simulators and public roads pose a challenge in collecting suitable data for feature identification and comparisons of performance among driver distraction detection algorithms. While the previous research focuses on improving prediction accuracy, shortening the prediction time is critical in giving timely warnings to drivers. This thesis aims at detecting driver distraction, which could provide faster and accurate warnings to drivers. The developed method is implemented by cutting the redundancy and irrelevant information fed to the algorithms and instead selecting suitable algorithms that achieve the balance between the prediction accuracy and prediction time. Moreover, a closed testing field supplies an environment for collecting more accurate information to identify the relevant features and to determine suitable algorithms. In this study, open-source data and experimental data are used. The results show that a balance between the prediction accuracy and the prediction time is achieved by feeding the relevant features and using suitable machine learning algorithms (e.g. Decision Tree). Compared with existing state-of-the-art methods, the prediction accuracy of the method proposed in this study has reached approximately the same level. More importantly, the efficiency has improved, including reduced prediction time and fewer input features. Consequently, less computer storage is used.PhD in Transport System

    CORE: Cooperative Reconstruction for Multi-Agent Perception

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    This paper presents CORE, a conceptually simple, effective and communication-efficient model for multi-agent cooperative perception. It addresses the task from a novel perspective of cooperative reconstruction, based on two key insights: 1) cooperating agents together provide a more holistic observation of the environment, and 2) the holistic observation can serve as valuable supervision to explicitly guide the model learning how to reconstruct the ideal observation based on collaboration. CORE instantiates the idea with three major components: a compressor for each agent to create more compact feature representation for efficient broadcasting, a lightweight attentive collaboration component for cross-agent message aggregation, and a reconstruction module to reconstruct the observation based on aggregated feature representations. This learning-to-reconstruct idea is task-agnostic, and offers clear and reasonable supervision to inspire more effective collaboration, eventually promoting perception tasks. We validate CORE on OPV2V, a large-scale multi-agent percetion dataset, in two tasks, i.e., 3D object detection and semantic segmentation. Results demonstrate that the model achieves state-of-the-art performance on both tasks, and is more communication-efficient.Comment: Accepted to ICCV 2023; Code: https://github.com/zllxot/COR

    Stock Volatility Prediction Based on Transformer Model Using Mixed-Frequency Data

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    With the increasing volume of high-frequency data in the information age, both challenges and opportunities arise in the prediction of stock volatility. On one hand, the outcome of prediction using tradition method combining stock technical and macroeconomic indicators still leaves room for improvement; on the other hand, macroeconomic indicators and peoples' search record on those search engines affecting their interested topics will intuitively have an impact on the stock volatility. For the convenience of assessment of the influence of these indicators, macroeconomic indicators and stock technical indicators are then grouped into objective factors, while Baidu search indices implying people's interested topics are defined as subjective factors. To align different frequency data, we introduce GARCH-MIDAS model. After mixing all the above data, we then feed them into Transformer model as part of the training data. Our experiments show that this model outperforms the baselines in terms of mean square error. The adaption of both types of data under Transformer model significantly reduces the mean square error from 1.00 to 0.86.Comment: Accepted by the 7th APWeb-WAIM International Joint Conference on Web and Big Data. (APWeb 2023

    Urban consumer trust and food certifications in China

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    China has experienced frequent food safety incidents that have undermined consumer trust in the food supply chain. To overcome this problem, China requalified the legislative framework and adopted a comprehensive food certification system over the years. Here, we investigated the influences of food traceability and Chinese certifications (QS/SC—food quality safety market access/production system, hazard-free, green, and organic) on Chinese consumer trust of food safety for different types of products: fish, meat, milk, eggs, and rice. Data were collected through face-to-face surveys conducted in rural and urban Chinese areas. With a sample of 757 questionnaires, we ran a logit model. The results show consumers’ uncertainty and skepticism of certifications guaranteeing food safety attributes, especially for animal-based products. We found that price is used as a cue of safety by Chinese consumers. Individuals with higher education seem less influenced by certifications and other cues included in the analysis. The findings demonstrate that Chinese policy makers should implement new strategies to enhance consumer food safety trust, and design policies by considering different categories (e.g., vegetables, meat, fish, etc.) of food

    Addressing China's grand challenge of achieving food security while ensuring environmental sustainability

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    China’s increasingly urbanized and wealthy population is driving a growing and changing demand for food, which might not be met without significant increase in agricultural productivity and sustainable use of natural resources. Given the past relationship between lack of access to affordable food and political instability, food security has to be given a high priority on national political agendas in the context of globalization. The drive for increased food production has had a significant impact on the environment, and the deterioration in ecosystem quality due to historic and current levels of pollution will potentially compromise the food production system in China. We discuss the grand challenges of not only producing more food but also producing it sustainably and without environmental degradation. In addressing these challenges, food production should be considered as part of an environmental system (soil, air, water, and biodiversity) and not independent from it. It is imperative that new ways of meeting the demand for food are developed while safeguarding the natural resources upon which food production is based. We present a holistic approach to both science and policy to ensure future food security while embracing the ambition of achieving environmental sustainability in China. It is a unique opportunity for China to be a role model as a new global player, especially for other emerging economies

    Study on coal seam physical characteristics and influence on stimulation: A case study of coal seams in zhengzhuang block

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    Coalbed Methane (CBM) is an unconventional form of natural gas which is self-generated and self-stored in coal seams. In order to realize the effective exploitation of CBM in Zhengzhuang block, microstructure, wettability, permeability, rock mechanics and in-situ stress of coal were studied in this research. It is found that high rank anthracite characterized by high vitrinite content and low inorganic mineral content, is abundant in CBM. More than 96% of inorganic minerals are clays dominated by kaolinite and illite. Various types of pores are developed on the coal. The wettability of coal differs from high to low to surface water, active water, and foam fracturing fluid; and contact angles of coal with active water and foam fracturing fluid decrease with the increase of burial depth. Gradients of fracture pressure and closure pressure in No.3 coal seam are higher than that of No.15 coal seam. The elastic modulus of coal is lower than that of sandstone. The construction curve of hydraulic fracturing shows that, when the construction flow rate and sand quantity are similar, the construction pressure of prepad in No.3 coal seam is lower than the pumping pressure of No.15 coal seam, but the propagated pressure is higher than that of No.15 coal seam. The drainage effect of No.3 coal seam with large pore volume, shallow burial depth and obvious fracture pressure is better than that of No.15 coal seam. The comprehensive understanding of coal physical properties and engineering practice in the block provide certain guiding significance to the CBM exploitation in Qinshui Basin

    Effects of elevated ozone on physiological, anatomical and ultrastructural characteristics of four common urban tree species in China

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    Fast urbanization has led to ozone (O3) being the main pollutant in summer in most of China. To assess future ground-level O3 effects on the service of urban greening species and clarify the underlying mechanism of O3 damage, four common urban greening species, Ailanthus altissima (AA), Fraxinus chinensis(FC), Platanus orientalis (PO) and Robinia pseudoacacia (RP) were exposed to non-filtered air (NF) and to elevated O3 (E-O3) in open-top chambers. E-O3 induced visible injury in all species as well as microscopic alterations such as collapse of the palisade parenchyma cells, callose accumulation, or chloroplast and mitochondrial accelerated senescence. E-O3 significantly reduced light-saturated CO2 assimilation (Asat),the maximum activity of Rubisco (Vcmax), the maximum electron transport rate (Jmax), and fluorescence parameters such as the quantum yield of noncyclic electron transport (�PSII), and the quenching of photochemical efficiency of PSII (qP). It also increased total antioxidant capacity, phenolics and ascorbate contents. No significant interaction between O3and species was found in photosynthetic performance and antioxidant systems, suggesting that the four species selected were sensitive to O3. Of all four species,AA was the most sensitive species due to a combination of earlier injury onset, anatomical features, lower antioxidant responses and higher stomatal conductance. The sensitivity of tree species to O3 is a factor to be considered for urban greening. Ozone may affect important urban forest ecosystem services by reducing CO2 assimilationThis study has been funded by the Hundred Talents Program, Chinese Academy of Sciences and State Key Laboratory of Urban and Regional Ecology. Collaboration between RCEES and Fundacion CEAM has been possible thanks to project AMIS (Fate and Impact of Atmospheric Pollutants, PIRSES-GA-2011-295132), and by the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists (grant number: 2013T2Z0009). VC also acknowledges the support of PROMETEOII/2014/038 project (Generalitat Valenciana, G.V.), and FGB and JRA that of PROMETEOII2013/021 (G.V.), and CGL2012-40058-C02-01/02 (MINECO). We thank Mr. Yulong Zhang for the experimental management.Gao, F.; Calatayud Lorente, V.; García-Breijo, F.; Reig Armiñana, J.; Feng, Z. (2016). Effects of elevated ozone on physiological, anatomical and ultrastructural characteristics of four common urban tree species in China. Ecological Indicators. 67:367-379. https://doi.org/10.1016/j.ecolind.2016.03.012S3673796
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