Analysis Of Spatial Structure Research Articles

Solar radiation visibility testing algorithm for precise shadow distribution for spatial steel structural thermal analysis under sunlight

As a large-span spatial steel structure, the radio telescope, characterized by its extensive span and numerous structural components, is sensitive to temperature gradients and susceptible to localized deformations induced by non-uniform temperature filed under sunlight, thereby affecting the operational performance. In order to calculate the shadow distribution of the structure, this study proposes a solar radiation visibility testing algorithm based on the depth buffer. To validate the accuracy of the proposed algorithm, the shadow distribution of a shading device is calculated employing the new algorithm, theoretical methods, and Ladybug tools. The results show that the shadow distribution obtained by the three methods is consistent. The thermal numerical simulation of the grid structure using the direct solar radiation calculated by the proposed algorithm is compared with the experiment results, and the error is below 5 %. Taking a radio telescope as an engineering application, the temperature distribution and pointing accuracy under solar are calculated. 9:00 and 16:00 have the worst pointing accuracy, while 11:00–13:00 has the best pointing accuracy. This study can provide a reference for the calculation of temperature field of spatial steel structure which is sensitive to sunlight temperature.

Narrative and Space: Reconstruction of Heritage Network for South Guangdong Ancient Post Road

The ancient post road in Southern Guangdong is a channel of communication inside and outside Lingnan in different historical periods. It is also known as a corridor of population migration, a channel of commodity exchange and an ancient road of civilization and culture. In view of the limitations of focusing on space while ignoring narrative in the previous research of ancient post road, the analysis method of narrative spatial structure was introduced herein. Based on the four main functions of the ancient post road in Southern Guangdong, including postal exchange, military war, commerce and trade, and official travel, the holistic and systematic narrative space study of the ancient post road in Southern Guangdong was carried out in order to construct a relatively complete narrative space structure of the heritage corridor network. Research showed that the four functional narrative points all rely on corridors. Its spatial structure took Guangzhou as the main core, with Leizhou and Yangjiang in western Guangdong and Chaozhou in eastern Guangdong as the sub-core. A waterway-based land as the auxiliary network system was formed; The post road shifted from the original military function to the economic function, experienced the internal communication with the Central Plains to the coastal areas, and then to the world through the Maritime Silk Road. It became the epitome of the historical development process of Lingnan region. The narrative spatial structure analysis method can deeply explore the historical characteristics and cultural connotation of the heritage corridor, and promote the overall cognition of the post road. The analysis results have certain guiding significance for the construction and protection of the heritage corridor network of the ancient post road in Southern Guangdong. It can also provide a reference for other scholars to carry out the research on similar heritage corridors.

Material Selection for Restoration of Genetic Diversity of Abies koreana on Mt. Jirisan in South Korea

: A strategy is required for selecting appropriate materials for the restoration of Abies koreana on Mt. Jirisan, where the habitat of A. koreana is continuously shrinking. The current study aimed to analyze the genetic characteristics of A. koreana in three subpopulations (Banyabong, Byeoksoryeng, and Cheonwangbong) on Mt. Jirisan using 10 nuclear simple sequence repeat (nSSR) markers and calculate the sampling distance for each subpopulation for avoiding genetically similar samples. Based on the calculated sampling distance, we proposed the size of a sample containing more than 95% of the alleles at a frequency greater than 0.05. AMOVA showed that the difference in genetic variation across subpopulations of A. koreana on Mt. Jirisan was small, approximately 3% of the total. Spatial genetic structure analysis results suggested that it would be appropriate to collect samples of the Banyabong subpopulation at intervals of 10 m or more, when sampling A. koreana, whereas for the Byeoksoryeong and Cheonwangbong subpopulations, samples should be collected at intervals of 20 m or more. Results of random sampling of 5 to 30 individuals indicated that, by applying a 10 m distance within the Banyabong subpopulation, more than 95% of the total alleles with a frequency ≥ 0.05 were secured when more than 25 individuals were extracted. Therefore, as a restoration strategy for A. koreana on Mt. Jirisan, we proposed the collection of more than 25 samples, keeping 10 m distance within the Banyabong subpopulation, which has a relatively high genetic diversity.

Algorithm for Point Cloud Dust Filtering of LiDAR for Autonomous Vehicles in Mining Area

With the continuous development of the transformation of the “smart mine” in the mineral industry, the use of sensors in autonomous trucks has become very common. However, the driving of trucks causes the point cloud collected by through Light Detection and Ranging (LiDAR) to contain dust points, leading to a significant decline in its detection performance, which makes it easy for vehicles to have failures at the perceptual level. In order to solve this problem, this study proposes a LiDAR point cloud denoising method for the quantitative analysis of laser reflection intensity and spatial structure. This method uses laser reflectivity as the benchmark template, constructs the initial confidence level template and initially screens out the sparse dust point cloud. The results are analyzed through the Euclidean distance of adjacent points, and the confidence level in the corresponding template is reduced for rescreening. The experimental results show that our method can significantly filter dust point cloud particles while retaining the rich environmental information of data. The computational load caused by filtering is far lower than that of other methods, and the overall operation efficiency of the system has no significant delay.

Discovering invariant spatial features in electron energy loss spectroscopy images on the mesoscopic and atomic levels

Over the last two decades, Electron Energy Loss Spectroscopy (EELS) imaging with a scanning transmission electron microscope has emerged as a technique of choice for visualizing complex chemical, electronic, plasmonic, and phononic phenomena in complex materials and structures. The availability of the EELS data necessitates the development of methods to analyze multidimensional data sets with complex spatial and energy structures. Traditionally, the analysis of these data sets has been based on analysis of individual spectra, one at a time, whereas the spatial structure and correlations between individual spatial pixels containing the relevant information of the physics of underpinning processes have generally been ignored and analyzed only via the visualization as 2D maps. Here, we develop a machine learning-based approach and workflows for the analysis of spatial structures in 3D EELS data sets using a combination of dimensionality reduction and multichannel rotationally invariant variational autoencoders. This approach is illustrated for the analysis of both the plasmonic phenomena in a system of nanowires and in the core excitations in functional oxides using low loss and core-loss EELS, respectively. The code developed in this manuscript is open sourced and freely available and provided as a Jupyter notebook for the interested reader.

Lifetime seismic fragility analysis of long-span spatial structures considering the wind-induced fatigue effect

Long-span spatial structures are susceptible to cumulative fatigue damage over their lifespan due to prolonged exposure to wind loads. The degradation in material properties resulting from fatigue can impact the structure's performance to resist earthquakes. However, previous studies and current design specifications do not address the issue of wind-induced fatigue in long-span spatial structures, making it difficult to evaluate the multihazard risk of the facilities under the combined action of fatigue and earthquakes. In this study, an assessment framework for the lifetime multihazard fragility of long-span spatial structures subjected to fatigue and earthquakes is developed to address this issue. The innovation of the proposed wind-induced fatigue analysis is that the influence of wind direction can be considered. Multihazard fragility surfaces are established with a mixed exponential model to assess the seismic fragility of the structure with different service times. The proposed method is applied to the seismic analysis of a typical single-layer Kiewitt-8 reticulated dome (SK8RD) to verify its feasibility. The results demonstrate that after 47 years of service, the ultimate bearing capacity of SK8RD decreases by 45.5% due to the wind-induced fatigue, while its collapse probability increases by 25.3% under the seismic action. Neglecting wind direction randomness and focusing solely on a single direction can lead to an overestimation of wind fatigue damage by more than twofold. Utilizing the probabilistic multihazard demand model based on the mixed exponential function enhances the regression accuracy by 12.9%, facilitating a more precise assessment of multihazard fragility for the SK8RD subjected to seismic and long-term wind fatigue. The proposed framework offers a valuable tool for evaluating multihazard risk considering the wind-induced fatigue for in-service long-span spatial structures.

Simultaneous monitoring of the limited area ionosphere with the use of GPS and ionosonde

The importance of this study lies in its contribution to the field of ionospheric science, particularly in the monitoring and prediction of ionospheric parameters. This study focuses on comparing two techniques for spatio-temporal kriging of critical ionospheric parameters, namely the F2 layer critical frequency (foF2) and Total Electron Content (TEC), under both quiet and disturbed ionospheric conditions. The first technique, Ordinary Kriging (OK), relies solely on foF2 data, while the second technique, Kriging with External Drift (KED), incorporates the dynamic relationship between foF2 and TEC data to improve the interpolation process. This study demonstrates how KED, which utilizes dynamic secondary information, offers advantages over OK. By simultaneously monitoring the ionosphere from a single ionosonde station and collecting data from visible GPS satellites, KED enhances the accuracy of spatial structural analysis, enabling more precise estimations of ionospheric characteristics across interpolation grid nodes. The research highlights that the non-uniform distribution of ionosonde stations, especially in regions with limited foF2 data, can benefit from KED's incorporation of TEC data. Additionally, the study reveals the potential for improving TEC maps by assimilating foF2 data located at the periphery of the observation area. Furthermore, the paper discusses the determination of semivariogram structures for both foF2 and TEC data, emphasizing the spatial correlations between data points. These findings contribute to a better understanding of ionospheric behavior and the potential for enhanced ionospheric modeling.

Buckling and post buckling analysis of spatial thin film structures under shearing based on perturbation method

Spatial thin film structures exhibit high sensitivity to shear deformation, often exhibiting wrinkling phenomena under minimal shear loads. In this study, we used a combined experimental and theoretical approach to investigate the wrinkling and post-buckling behaviors of thin films subjected to shear forces. Initially, we designed and fabricated a high-precision experimental apparatus, which, in conjunction with the MTS Exceed 40 series universal testing machine, was a versatile experimental platform for evaluating the responses of thin films to shear. Subsequently, we extended the classical Föppl–von Kármán nonlinear plate model to capture the large deformation behaviors of thin films under shear. This development led to the formulation of governing equations that describe the shear-induced deformation of the films. We introduced two boundary conditions to characterize these deformations: one in which the non-loaded edge was free (unconstrained), and another in which the non-loaded edge was constrained (analogous to a frame constraining a painting). To solve the governing equations, we treated the incremental shear displacement angle of the thin film as a small parameter and devised a numerical method grounded in perturbation theory. We further formulated an implicit difference method of arbitrary order accuracy to enhance the precision and stability of the numerical solution. Our experimental and theoretical analyses revealed a comprehensive buckling pathway for thin films under shear, characterized by an initial wrinkling configuration (Config. 1), followed by a transition to a secondary wrinkling state (Config. 2), and culminating in a wrinkling splitting pattern (Config. 3). We also determined that by increasing the pre-stretching of thin films, their resistance to wrinkling along the entire buckling pathway could be significantly enhanced.

Spatial Structure Analysis in Regional Development Context at Samosir Regency

Regional inequality or disparity is a natural consequence of development and an unavoidable stage. This happens because of differences in population, natural resource potential and geographical conditions in each region. This research aims to analyze public service centers, inter-district interactions, and settlement patterns in the context of regional development in Samosir Regency. The study uses a descriptive method with a quantitative approach to analyze the centers of public services, inter-district interactions, and settlement patterns among districts in Samosir Regency using the tools of centrality index analysis, gravity model, and nearest neighbor analysis. The analysis results show that the public service facilities in Samosir Regency in 2021 include 517 units of educational facilities, 442 units of healthcare facilities, 561 units of religious facilities, and 2,418 units of economic facilities, with the service center located in Pangururan District with a total availability of 1,081 units, which has the highest centrality value of 966.63. The largest inter-district interactions occur in Palipi District with a total interaction of 11,671,532.31, while the smallest interaction occurs in Simanindo District with a total interaction of 749,250.15. The settlement pattern in Samosir Regency consists of 1 district with a random settlement pattern and 8 other districts with clustered settlement patterns. In the development of Samosir Regency, the influence of district interactions, service centers, and settlement patterns are important factors to be considered.Keywords: District, Service Center, Interaction, Settlement Pattern

Study of Biopharmaceutical Agricultural Development in Karanganyar Regency

Agriculture in Karanganyar Regency is not considered a primary sector in the Solo Raya area; however, it possesses untapped potential that needs to be developed. Medicinal plants, or bio-pharmaceutical commodities, are among the prominent potentials, with Karanganyar Regency ranking among the top 10 highest producers in Central Java Province and having seven sub-districts as centres for medicinal plant cultivation. Ginger, turmeric, and galangal are outstanding commodities in the Agricultural Region of Karanganyar, identified as potential and key commodities based on linkage system analysis, agropolitan subsystem analysis, spatial structure analysis, LQ and shiftshare analysis, policy analysis, and land carrying capacity analysis. The analysis reveals the presence of potential and challenges as driving and inhibiting factors. Nevertheless, the bio-pharmaceutical agriculture sector faces several issues, such as inadequate support in terms of facilities and infrastructure, as well as imbalances in inter-regional infrastructure conditions that impact marketing disparities. Additionally, monitoring and reporting of agricultural sector development programs are not yet optimal. Therefore, further analysis and studies are needed to develop the agricultural sector, particularly in the bio-pharmaceutical commodities domain.

Seismic Response Analysis of Dome-Shaped Large Spatial Structures According to TMD Installation

Seismic Response Analysis of Dome-Shaped Large Spatial Structures According to TMD Installation

Immersive Environment as a Tool for Changing Human-Centric Optic

The article is devoted to the scientific problem of theoretical elaboration and contextualization of an immersive environment implemented in the physical space of a gallery or museum, as well as a site-specific work, or in VR and AR, which work to change anthropocentric optics. The aim of the research is to identify the peculiarities of the formation of an immersive environment and the practice of creating VR and AR projects in Ukrainian contemporary art, to identify the work of Ukrainian artists, which takes place outside the country at the intersection of the latest ideas in European culture with a focus on the relationship between human and nature. The task is to study the theoretical foundations of the subjectivity of nature and the development of immersive environments, review and analysis of projects that use digital technologies to create immersion. The methodology of the study consists in theoretical and field researches at the intersection of eco-topics and immersive technologies and the development of author's experiments as part of the research "Analytical Instruments for Audio-Visual Translation of Metabolomics" merging genotype and environment regarding climate changes at Iméra — the Institute of Advanced Studies in Marseille. The main method is a comprehensive approach to highlight issues of the development of deep ecology, the theory of symbiosis, visual and photometric methods, analysis of concepts, spatial structure and artistic works. The peculiarities of creating an immersive environment in physical space were explored in the projects "Cosmogony", "Homage to Leonardo", "Garden of Divine Songs" after Hryhorii Skovoroda, "Homage to Matisse", "Gaia", "The Ocean", "Espace Ocean: Waters Come Into My Soul", "Ecocide", which analyzes the impact of the ongoing war on ecology, in order to be included into the national art discourse. The concept of "non-human agency" is concidered as an imperative of nature's subjectivity. The possibilities of molecular sonification in metabolomics were analyzed. A brief overview of the VR projects "Invasions 1.2.3", "Atmospheric Forest" and "First Day" and AR "Vegetable Kingdom, Vegetable Anarchy" is provided. Festivals OVNi in Nice, Scientifica #2 in Marseille, Ars Electronica in Linz, RIXC in Riga, UNESCO Media Art City in Karlsruhe and Venice Immersive are considered as platforms for the construction of "future civilization". The instrumentality of immersive environments for changing anthropocentric optics has been revealed.

Forest digital twin: A new tool for forest management practices based on Spatio-Temporal Data, 3D simulation Engine, and intelligent interactive environment

Existing forest digitization studies focus on one-way forest management practice visualization simulation, lacking decision-making feedback and virtual-real interaction synchronization. This paper presents the vision of the forest digital twin paradigm. We construct a forest digital twin to explore a new digital carrier of forest resources using remote sensing data, forest inventory data, the Cesium Digital Earth Engine, forest planning theory and parametric 3D modeling technology. The two-way interaction and thinning experiments showed that the forest digital twin could provide a novel pattern for in-depth analysis of forest spatial structure, individual tree dynamic growth and human-digital twin interaction effects. The successful recognition rate in matching the forest structure seen on real forest structure images with the forest digital scene was 91.3%, indicating that the forest digital twin can characterize the real forest structure significantly. The prediction accuracy of the multi-grade growth model integrating the Bayesian method for DBH, H was more than 90.4%. In addition, ASS-FDT interaction is superior to the assessors (ASS) and forest digital twin (FDT) for stand spatial structure overall optimization. The multi-dimensional stand spatial structure index (F-index) increased by 22.82%. The constructed forest digital twin model shows superior performance in optimizing the stand growth model and enhancing the overall stand spatial structure under the decision-making feedback and real-time interaction strategies. The automatic operation pattern provides a user-friendly forest management practice solution.

Multiscale spatial patterns and environmental drivers of seamount and island slope megafaunal assemblages along the Mozambique channel

Seamounts are vulnerable ecosystems targeted by fishing and potentially by future mineral exploitation. Their abundance, widespread distribution, and heterogeneity of faunal and abiotic components require integrated studies at multiscale to describe spatial patterns and identify environmental drivers needed by conservation plans. There is also a lack of knowledge on seamount benthic ecosystems in some regions, such as the Indian Ocean. These gaps, in the context of Marine Protected Areas establishment in the region, have motivated the present study focusing on the Mozambique Channel Eparses islands and flat top seamounts, along a 10-degree latitude gradient. These structures are characterized by complex volcanic and carbonate geomorphologies at multiscale and are distributed along a highly dynamic turbulent ocean circulation area with large anticyclonic eddies. For the first time, we analysed, from seabed image transects obtained by towed-camera on four seamounts, and two volcanic islands - Bassas da India and Mayotte - external slopes, and from multiscale environmental data, how benthic communities respond to this high habitat heterogeneity at regional, and local scales. This study reveals high discrepancies of benthic megafauna richness, density, and beta diversity among seamounts and among slopes of the same islands. Moreover, at similar latitude, seamounts display higher densities than island slopes. The highest densities found on a seamount of the Glorieuses archipelago are explained by strong currents and flat homogeneous geomorphology. Except on this seamount, the beta diversity is high, despite the quite limited depth range explored (84–734 m) and is the highest on island slopes and Hall Bank, driven by the diversity and hardness of the substrate. Beta diversity is mainly due to taxa turnover, with high contribution of the habitat-forming sponges and cnidarians, together with a few mobile taxa. We identified from biogeographic network analysis 12 dominant faunal assemblages, displaying a patchy distribution, with variability in composition both among and within sites. Currents and primary productivity explain ∼15% of the observed assemblage structure along the channel, while geomorphology (km scale), topography (60–500 m scale) and substrate (60-m units) explain together 24% of the faunal spatial patterns. Analysis of spatial structures along island slopes detected some small (100–200 m), medium (∼1 km) and large scale (∼2–6 km) megabenthic community structures, partly explained by topography, substrate, depth, and slope. Despite limited taxonomic identifications for this poorly sampled area, this study reveals an outstanding heterogeneity of megabenthic assemblages at multispatial scales in the Mozambique Channel seamounts and island slopes, in response to the complex hydrography and geology of the area. Further characterization of environmental drivers with greater focus at local scales including hydrographic variables are therefore needed to improve predictions of suitable habitats of vulnerable marine ecosystems.

Late Miocene mammalian burrows in the Camacho Formation of Uruguay reveal a complex community of ecosystem engineers

We report fossil mammal burrows from backshore beach facies in the Camacho Formation of southern Uruguay, of Late Miocene (Huayquerian SALMA) age. The presence of desiccation cracks and rhizoliths indicate the occurrence of relatively extended periods of subaerial exposure and the incipient development of vegetation. The analysis of the burrows' spatial extent, size, and structure reveals the existence of exceptionally well-preserved and intercrossing tunnel systems. We show the existence of different size classes of burrows, which indicate that at least four different taxa were responsible for their construction. Considering the inferred body masses of the trace makers obtained from allometric relationships and the body masses of taxa recovered for the Camacho Formation, the burrows may have been produced by a combination of the following mammals: one of several rodents, notoungulates, cingulates, folivorans, and a carnivoran. The fossil association represents an exceptional case of a community of ecosystem engineers in the Late Miocene of southeastern South America.

Dispersal capacities of pollen, seeds and spores: insights from comparative analyses of spatial genetic structures in bryophytes and spermatophytes.

The dramatic fluctuations of climate conditions since the late Tertiary era have resulted in major species range shifts. These movements were conditioned by geographic barriers and species dispersal capacities. In land plants, gene flow occurs through the movement of male gametes (sperm cells, pollen grains), which carry nDNA, and diaspores (spores, seeds), which carry both cpDNA and nDNA, making them an ideal model to compare the imprints of past climate change on the spatial genetic structures of different genomic compartments. Based on a meta-analysis of cpDNA and nDNA sequence data in western Europe, we test the hypotheses that nDNA genetic structures are similar in bryophytes and spermatophytes due to the similar size of spores and pollen grains, whereas genetic structures derived from the analysis of cpDNA are significantly stronger in spermatophytes than in bryophytes due to the substantially larger size of seeds as compared to spores. Sequence data at 1-4 loci were retrieved for 11 bryophyte and 17 spermatophyte species across their entire European range. Genetic structures between and within southern and northern populations were analyzed through F and N statistics and Mantel tests. Gst and Nst between southern and northern Europe derived from cpDNA were significantly higher, and the proportion of significant tests was higher in spermatophytes than in bryophytes. This suggests that in the latter, migrations across mountain ranges were sufficient to maintain a homogenous allelic structure across Europe, evidencing the minor role played by mountain ranges in bryophyte migrations. With nDNA, patterns of genetic structure did not significantly differ between bryophytes and spermatophytes, in line with the hypothesis that spores and pollen grains exhibit similar dispersal capacities due to their size similarity. Stronger levels of genetic differentiation between southern and northern Europe, and within southern Europe, in spermatophytes than in bryophytes, caused by higher long-distance dispersal capacities of spores as compared to seeds, may account for the strikingly higher levels of endemism in spermatophytes than in bryophytes in the Mediterranean biodiversity hotspot.

Landscape genetics identified conservation priority areas for blue sheep (Pseudois nayaur) in the Indian Trans-Himalayan Region

The trans-Himalayan region of India, although have xeric features, still supports a unique assemblage of biodiversity, including some of the charismatic and endemic species. In the present study, we studied blue sheep (Pseudois nayaur) across the distribution range in the Western trans Himalayas of India and found about 18,775 km2 area suitable for blue sheep. The explicit Bayesian based spatial and non-spatial population structure analysis assigned blue sheep into two genetic populations, i.e., Ladakh and Lahaul-Spiti. We found relatively high genetic divergence in blue sheep which is also supported by the low current flow in Circuitscape model. With the multiple evidences, we explain landscape resistance facilitated by the landscape heterogeneity, and large patches of unsuitable habitats forced population divergence and poor functional connectivity. We found that blue sheep population has been demographically stable in the past, but showed a slight decline within the last few decades. This study is the first range-wide attempt to exhibit landscape features in shaping the spatial distribution, genetic structure and demography patterns of blue sheep in Western Himalayas, and will be of use in the conservation and management planning of blue sheep.

Study on the Spatial Structure of the Complex Network of Population Migration in the Poyang Lake Urban Agglomeration

Population constitutes the foundational element of cities, and population migration drives the transfer of production factors among urban areas. The population migration network serves as an objective representation of intercity interactions, bearing great significance for the analysis of urban network spatial structure. This study focuses on the 10 core cities within the Poyang Lake urban agglomeration. It utilizes population migration data from Tencent’s location-based big data spanning from 2015 to 2018. Employing the point-axis theory from spatial network theory and the directed weighted network theory within the complex network, the study establishes a comprehensive set of network indices and a network model for spatial structure. It investigates the dynamics of population migration networks within the urban agglomeration and considers strategies for enhancing, regulating, or guiding urban agglomeration development to strengthen its overall vitality. The findings indicate that the urban agglomeration displays distinct characteristics of an urban hierarchical sequence and demonstrates gradual improvement in its spatial network development. While network density remains relatively stable across various threshold intervals over an extended period, network connectivity remains weak. Moreover, the urban agglomeration exhibits the lowest degree of centralization, the highest network structure entropy, and limited network connectivity. Migration along the primary power axis within the urban agglomeration remains relatively stable, while the internal network of the urban agglomeration is interconnected through a “core-non-core” network, reflecting near-geographical connection characteristics. Variations in spatial structure are observed, with the spatial network structure following two modes: “weak core city + edge city” and “node city + outer network city”. The trend in network connections diversifies, resulting in both “core-edge” connections and cross-regional connections. In conclusion, the network characteristics of the urban agglomeration surrounding Poyang Lake are consolidated to aid in formulating an optimization plan for the urban agglomeration’s spatial structure. Additionally, these findings serve as a reference for studying the evolution of spatial structures in the other two urban agglomerations within the city agglomeration in the middle reaches of the Yangtze River.

Analysis of spatial structure and filling mechanism of a paleokarst channel against a background of denudation: A case study in the Tahe Oilfield, Tarim basin

Accurate delineations of the formation chronology and sedimentary characteristics of underground rivers are crucial for prospecting karst reservoirs. Based on drilling records, core samples, seismic data, and thin-section microscopy, qualitative and quantitative analyses of the fillings within the S65 karst channel, located within the erosional zone of the Tahe Oilfield Conventional seismic data, acoustic impedance inversion seismic data, mud inversion seismic data, and well drilling data were used to elucidate the lateral variations and combinations of fillings. Key coring wells were selected, and cores were calibrated using logging data on acoustic time difference (AC), density (DEN), deep-shallow dual lateral resistivity (RD-RS), natural gamma ray (GR), and shale content (Vsh). A range of quantitative benchmarks were thus established to distinguish between various types of fillings. Discrimination between breakdown breccia and calcite fillings was achieved using AC-DEN crossplots. The former exhibited elevated DEN values (2.64–2.72) coupled with moderate AC values (>49.5). Conversely, the latter displayed higher DEN values (2.66–2.76) and lower AC values (<49.5). Mechanical components and unfilled or low-filled components were identified using GR-RS or △R-Vsh crossplots, where △R signified the absolute difference between deep and shallow resistivity measurements, with a GR value of 20 API and a Vsh value of 5% within these plots representing the boundary between the two. The filling characteristics of the underground river fillings, and the mechanisms underlying the formation of these fillings were explained. A comparative analysis of the channels during different geological epochs revealed the following: (i) Sandstone and sandstone-cemented breakdown breccia that were primarily filled with a combination of mechanical and collapse fillings developed in the doline. Mudstone and calcite developed in the corridor region, whereas breakdown breccia developed at the intersections of fault lines. Uncemented breakdown breccia was frequently encountered in the branches of the underground river, with calcite developed on the blind side. (ii) The top channel of the S65 underground river formed during a period of rising sea levels in the Carboniferous. The poor lateral reservoir connectivity resulted from the extensive infiltration of mud. In contrast, the bottom channel, primarily consisting of Silurian sandstone and sandstone-cemented breakdown breccia, formed during the denudation phase of the early Hercynian. This bottom channel played a significant role in the substantial oil and gas production within the underground river system.

Fine-scale genetic structure of co-occurring seagrass species highlights the importance of repeated seedling recruitment (Leyte Island, Philippines)

Seagrasses are recognized for their fundamental and ecological functions in coastal environments. Movement ecology and dispersal mechanism of organisms are hypothesized to have a profound significance for the dynamics and resilience of populations and ecosystems. We tested this hypothesis by comparing the genetic diversity and fine-scaled structure of co-occurring seagrass populations of Thalassia hemprichii and Cymodocea serrulata, which differ in their survival strategy and movement ecology. Two hundred eighty-four and two hundred sixty-three individuals of T. hemprichii and C. serrulata from 6 seagrass meadows along Leyte, Philippines were genotyped using 15 and 9 microsatellite markers, respectively. Thalassia hemprichii was observed to have higher genotypic diversity, while clonal elongation was more pronounced for C. serrulata. Repeated seedling recruitment followed by rhizome elongation was observed as an important strategy of resilience and indicated the complementary importance of both sexual and asexual reproduction of these species. Moreover, fine-scale spatial structure analysis revealed that repeated seed recruitment and pollen flow occurred locally, yielding higher kinship values at very close distances of < 5 m, indicating its importance for the maintenance of genetic diversity. An individual based STRUCTURE analysis showed three putative gene pools for both species. Overall, our findings have important implications for understanding the processes and dynamics of populations before conservation efforts. Depending on the strategy of the species, efforts should focus on preserving natural expansion of existing beds and enabling local seed recruitment for successful conservation.