Anthropogenic Activities Generate High-Refractory Black Carbon along the Yangtze River Continuum

12 pages, 7 figuresCombustion-driven particulate black carbon (PBC) is a crucial slow-cycling pool in the organic carbon flux from rivers to oceans. Since the refractoriness of PBC stems from the association of non-homologous char and soot, the composition and source of char and soot must be considered when investigating riverine PBC. Samples along the Yangtze River continuum during different hydrological periods were collected in this study to investigate the association and asynchronous combustion drive of char and soot in PBC. The results revealed that PBC in the Yangtze River, with higher refractory nature, accounts for 13.73 ± 6.89% of particulate organic carbon, and soot occupies 37.53 ± 11.00% of PBC. The preponderant contribution of fossil fuel combustion to soot (92.57 ± 3.20%) compared to char (27.55 ± 5.92%), suggested that fossil fuel combustion is a crucial driver for PBC with high soot percentage. Redundancy analysis and structural equation modeling confirmed that the fossil fuel energy used by anthropogenic activities promoting soot is the crucial reason for high-refractory PBC. We estimated that the Yangtze River transported 0.15–0.23 Tg of soot and 0.15–0.25 Tg of char to the ocean annually, and the export of large higher refractory PBC to the ocean can form a long-term sink and prolong the residence time of terrigenous carbonThis study was supported by grants from the National Natural Science Foundation of China (nos. 42277214, 42207256, and 41971286), major programs of the National Social Science Foundation of China (grant nos. 22&ZD136), the Special Science and Technology Innovation Program for Carbon Peak and Carbon Neutralization of Jiangsu Province (grant no. BE2022612)Peer reviewe

Surveying and Mapping Geographical Information from the Perspective of Geography

It briefly reviewed the history of geographic information content development since the existence of geographic information system. It pointed out that the current definition of geographic information is always the extension from the "spatial+ attributes" basic mapping framework of geographic information. It is increasingly difficult to adapt to the analysis and application of spatial-temporal big data. From the perspective of geography research subject and content, it summarized systematically that the content and extension of the "geographic information" that geography needs. It put forward that a six-element expression model of geographic information, including spatial location, semantic description, attribute characteristics, geometric form, evolution process, and objects relationship.Under the guidance of the laws of geography, for geographical phenomenon of spatial distribution, temporal pattern and evolution process, the interaction mechanism of the integrated expression, system analysis and efficient management, it designed that a unified GIS data model which is expressed by six basic elements, a new GIS data structure driven by geographical rules and interaction, and key technologies of unstructured spatio-temporal data organization and storage. It provided that a theoretical basis and technical support for the shift from the surveying and mapping geographic information to the scientific geographic information, and it can help improving the organization, management, analysis and expression ability of the GIS of the geographical laws such as geographical pattern, evolution process, and interaction between elements

Spatio-Temporal Constrained Human Trajectory Generation from the PIR Motion Detector Sensor Network Data: A Geometric Algebra Approach

Passive infrared (PIR) motion detectors, which can support long-term continuous observation, are widely used for human motion analysis. Extracting all possible trajectories from the PIR sensor networks is important. Because the PIR sensor does not log location and individual information, none of the existing methods can generate all possible human motion trajectories that satisfy various spatio-temporal constraints from the sensor activation log data. In this paper, a geometric algebra (GA)-based approach is developed to generate all possible human trajectories from the PIR sensor network data. Firstly, the representation of the geographical network, sensor activation response sequences and the human motion are represented as algebraic elements using GA. The human motion status of each sensor activation are labeled using the GA-based trajectory tracking. Then, a matrix multiplication approach is developed to dynamically generate the human trajectories according to the sensor activation log and the spatio-temporal constraints. The method is tested with the MERL motion database. Experiments show that our method can flexibly extract the major statistical pattern of the human motion. Compared with direct statistical analysis and tracklet graph method, our method can effectively extract all possible trajectories of the human motion, which makes it more accurate. Our method is also likely to provides a new way to filter other passive sensor log data in sensor networks

Barycenter reflected equatorial Pacific sea level structure evolution and its indication of ENSO events

Focused on the zonal and meridional response of sea level change to El Niño-Southern Oscillation (ENSO) events, this paper retrieves the overall average, positive anomaly and negative anomaly sea surface height (SSH) series of equatorial Pacific area (EPA) from satellite altimetry data from 1993 to 2013. The barycenter method is then applied to each of the three series to get the zonal and meridional barycenter coordinates. The barycenter coordinates are then compared with the Multivariate ENSO index (MEI) to reveal the zonal and meridional response of sea level change to ENSO. The meridional and zonal spatio-temporal evolutionary processes of sea level change in EPA during different ENSO events are reconstructed by the Principle Tensor Analysis of Rank 3 Method (PTA3). Comparative analysis shows that the meridional change of positive anomalies barycenter, rather than the mean series of sea level height anomaly in EPA, can well characterize the intensity and evolutionary process of ENSO events. Meanwhile, the zonal migration of barycenter may reflect the lag adjustment of the sea level to the ENSO signal. The analysis on the meridional and zonal evolution of the sea level change in different ENSO periods shows that the response of sea level change to the ENSO events can be mainly characterized by the position differences between positive and negative sea level anomaly barycenter, SSH gradient in the meridional direction and the inconsistency in the overall spatial structure and temporal evolution characteristics in the zonal direction

Impact of Cryogenic Treatment Process on the Performance of 51CrV4 Steel

The working load on automotive components is continuously rising, and the mechanical performance requirements for component materials are rising along with the growth trend toward light weight and high dependability in automobiles. In this study, the response characteristics of 51CrV4 spring steel were taken to be its hardness, wear resistance, tensile strength, and impact toughness. Prior to tempering, cryogenic treatment was introduced. Through the Taguchi method and gray relational analysis, the ideal process parameters were discovered. The ideal process variables were the following: a cooling rate of 1 °C/min, a cryogenic temperature of −196 °C, a holding time of 24 h, and a cycle number of three. An analysis of variance revealed that the holding time had the greatest effect on the material properties, with an effect of 49.01%. The yield limit of 51CrV4 was increased by 14.95% and the tensile strength was increased by 15.39% with this group of processes, and the wear mass loss was reduced by 43.32%. The mechanical qualities had a thorough upgrade. Microscopic analysis revealed that cryogenic treatment resulted in refinement of the martensite structure and significant differences in orientation. Additionally, bainite precipitation occurred, exhibiting a fine needle-like distribution, which positively influenced impact toughness. Analysis of the impact fracture surface showed that cryogenic treatment led to an increase in dimple diameter and depth. Further analysis of the elements revealed that calcium (Ca) weakened the negative effect of sulfur (S) on 51CrV4 spring steel. The overall improvement in material properties provides guidance for practical production applications

Optimal Route Searching with Multiple Dynamical Constraints—A Geometric Algebra Approach

The process of searching for a dynamic constrained optimal path has received increasing attention in traffic planning, evacuation, and personalized or collaborative traffic service. As most existing multiple constrained optimal path (MCOP) methods cannot search for a path given various types of constraints that dynamically change during the search, few approaches for dynamic multiple constrained optimal path (DMCOP) with type II dynamics are available for practical use. In this study, we develop a method to solve the DMCOP problem with type II dynamics based on the unification of various types of constraints under a geometric algebra (GA) framework. In our method, the network topology and three different types of constraints are represented by using algebraic base coding. With a parameterized optimization of the MCOP algorithm based on a greedy search strategy under the generation-refinement paradigm, this algorithm is found to accurately support the discovery of optimal paths as the constraints of numerical values, nodes, and route structure types are dynamically added to the network. The algorithm was tested with simulated cases of optimal tourism route searches in China’s road networks with various combinations of constraints. The case study indicates that our algorithm can not only solve the DMCOP with different types of constraints but also use constraints to speed up the route filtering

Geographic scenario: a possible foundation for further development of virtual geographic environments

It has been two decades since virtual geographic environments (VGEs) were initially proposed. While relevant theories and technologies are evolving, data organization models have always been the foundation of VGE development, and they require further exploration. Based on the comprehensive consideration of the characteristics of VGEs, geographic scene is proposed to organize geographic information and data. We empirically find that geographic scene provides a suitable organization schema to support geo-visualization, geo-simulation, and geo-collaboration. To systematically investigate the concept and method of geographic scene, Geographic Scenario is proposed as the theory on developing geographic scene, and corresponding key issues of the Geographic Scenario are illustrated in this article. Prospects of the proposed method are discussed with the hope of informing future studies of VGEs