72 research outputs found
Chlorine and Bromine Isotope Fractionation of Halogenated Organic Pollutants on Gas Chromatography Columns
Compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) has become a
useful approach for degradation pathway investigation and source appointment of
halogenated organic pollutants (HOPs). CSIA-Cl/Br is usually conducted by gas
chromatography-mass spectrometry (GC-MS), which could be negatively impacted by
chlorine and bromine isotope fractionation of HOPs on GC columns. In this
study, 31 organochlorines and 4 organobromines were systematically investigated
in terms of Cl/Br isotope fractionation on GC columns using GC-double focus
magnetic-sector high resolution MS (GC-DFS-HRMS). On-column chlorine/bromine
isotope fractionation behaviors of the HOPs were explored, presenting various
isotope fractionation modes and extents. Twenty-nine HOPs exhibited inverse
isotope fractionation, and only polychlorinated biphenyl-138 (PCB-138) and
PCB-153 presented normal isotope fractionation. And no observable isotope
fractionation was found for the rest four HOPs, i.e., PCB-101,
1,2,3,7,8-pentachlorodibenzofuran, PCB-180 and 2,3,7,8-tetrachlorodibenzofuran.
The isotope fractionation extents of different HOPs varied from below the
observable threshold (0.50%) to 7.31% (PCB-18). The mechanisms of the on-column
chlorine/bromine isotope fractionation were tentatively interpreted with the
Craig-Gordon model and a modified two-film model. Inverse isotope effects and
normal isotope effects might contribute to the total isotope effects together
and thus determine the isotope fractionation directions and extents. Proposals
derived from the main results of this study for CSIA-Cl/Br research were
provided for improving the precision and accuracy of CSIA-Cl/Br results. The
findings of this study will shed light on the development of CSIA-Cl/Br methods
using GC-MS techniques, and help to implement the research using CSIA-Cl/Br to
investigate the environmental behaviors and pollution sources of HOPs.Comment: 30 pages, 5 figure
CasFusionNet: A Cascaded Network for Point Cloud Semantic Scene Completion by Dense Feature Fusion
Semantic scene completion (SSC) aims to complete a partial 3D scene and
predict its semantics simultaneously. Most existing works adopt the voxel
representations, thus suffering from the growth of memory and computation cost
as the voxel resolution increases. Though a few works attempt to solve SSC from
the perspective of 3D point clouds, they have not fully exploited the
correlation and complementarity between the two tasks of scene completion and
semantic segmentation. In our work, we present CasFusionNet, a novel cascaded
network for point cloud semantic scene completion by dense feature fusion.
Specifically, we design (i) a global completion module (GCM) to produce an
upsampled and completed but coarse point set, (ii) a semantic segmentation
module (SSM) to predict the per-point semantic labels of the completed points
generated by GCM, and (iii) a local refinement module (LRM) to further refine
the coarse completed points and the associated labels from a local perspective.
We organize the above three modules via dense feature fusion in each level, and
cascade a total of four levels, where we also employ feature fusion between
each level for sufficient information usage. Both quantitative and qualitative
results on our compiled two point-based datasets validate the effectiveness and
superiority of our CasFusionNet compared to state-of-the-art methods in terms
of both scene completion and semantic segmentation. The codes and datasets are
available at: https://github.com/JinfengX/CasFusionNet
Integrated Control of Hydromechanical Variable Transmissions
A hydromechanical variable transmission (HMT) has advantages of continuous variation and high efficiency. So it is one of the ideal transmissions of heavy vehicles. The continuous speed varying process involves speed governing in range and range shift. Integrated control strategy of the HMT is proposed in this paper. The algorithm of the asymmetric saturated incremental proportional integral derivative (PID) speed control strategy in range and range shift conditions are derived. And this paper presents the range shift logic and range shift control strategies. A controller model is built in Matlab Simulink and cosimulated with the model of vehicle equipped with a two-range HMT. The HMT prototype hardware-in-the-loop simulation (HILS) platform of the integrated control strategy is built. The HILS results show that the range shift process is smooth and speed fluctuation does not happen. In the throttle stable stage, the engine speed is adjusted to the near optimal speed, and its change rules are in accordance with simulation results. The integrated control strategy is reasonable
Point-Bind & Point-LLM: Aligning Point Cloud with Multi-modality for 3D Understanding, Generation, and Instruction Following
We introduce Point-Bind, a 3D multi-modality model aligning point clouds with
2D image, language, audio, and video. Guided by ImageBind, we construct a joint
embedding space between 3D and multi-modalities, enabling many promising
applications, e.g., any-to-3D generation, 3D embedding arithmetic, and 3D
open-world understanding. On top of this, we further present Point-LLM, the
first 3D large language model (LLM) following 3D multi-modal instructions. By
parameter-efficient fine-tuning techniques, Point-LLM injects the semantics of
Point-Bind into pre-trained LLMs, e.g., LLaMA, which requires no 3D instruction
data, but exhibits superior 3D and multi-modal question-answering capacity. We
hope our work may cast a light on the community for extending 3D point clouds
to multi-modality applications. Code is available at
https://github.com/ZiyuGuo99/Point-Bind_Point-LLM.Comment: Work in progress. Code is available at
https://github.com/ZiyuGuo99/Point-Bind_Point-LL
Information Security Terminal Architecture of Power Transportation Mobile Internet of Things Based on Big Data Analysis
The progress of the social economy and the rapid development of the power field have created more favorable conditions for the construction of my country’s power grid. In this network age, how to further realize the connection between the power system and the Internet of Things is the key content of many scholars’ research. In the Internet of Things environment, there have been many excellent results in the collection, storage, and management of electric power big data, but the problem of information security has not been completely solved. Based on big data analysis and Internet of Things technology, this paper studies the architecture design of power information security terminals. In view of the diverse types of power grid mobile information and the large amount of data, this paper designs a power transportation mobile information security management system structure, which improves the effective management of power data by the system through big data, smart sensors, and wireless communication technology. According to the experiment, the power information security terminal constructed in this paper can effectively reduce communication resources and save communication costs in the process of aggregating multidimensional data. In the user satisfaction survey, residents’ satisfaction with the convenience and safety of the intelligent power system is also as high as 9.312 and 9.233. On the whole, the application of big data and Internet of Things technology to the construction of power information security terminals can indeed improve the service efficiency of power companies under the premise of ensuring safety and allow users to have a better experience
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