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Search Results (947)

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25 pages, 9415 KiB  
Article
Spatial and Seasonal Variation and the Driving Mechanism of the Thermal Effects of Urban Park Green Spaces in Zhengzhou, China
by Yuan Feng, Kaihua Zhang, Ang Li, Yangyang Zhang, Kun Wang, Nan Guo, Ho Yi Wan, Xiaoyang Tan, Nalin Dong, Xin Xu, Ruizhen He, Bing Wang, Long Fan, Shidong Ge and Peihao Song
Land 2024, 13(9), 1474; https://doi.org/10.3390/land13091474 (registering DOI) - 11 Sep 2024
Abstract
Greenscaping, a key sustainable practice, helps cities combat rising temperatures and climate change. Urban parks, a pivotal greenscaping element, mitigate the urban heat island (UHI) effect. In this study, we utilized high-resolution remote sensing imagery (GF-2 and Landsat 8, 9) and in situ [...] Read more.
Greenscaping, a key sustainable practice, helps cities combat rising temperatures and climate change. Urban parks, a pivotal greenscaping element, mitigate the urban heat island (UHI) effect. In this study, we utilized high-resolution remote sensing imagery (GF-2 and Landsat 8, 9) and in situ measurements to analyze the seasonal thermal regulation of different park types in Zhengzhou, China. We calculated vegetation characteristic indices (VCIs) and landscape patterns (LMs) and employed boosted regression tree models to explore their relative contributions to land surface temperature (LST) across different seasons. Our findings revealed that urban parks lowered temperatures by 0.65 °C, 1.41 °C, and 2.84 °C in spring, summer, and autumn, respectively, but raised them by 1.92 °C in winter. Amusement parks, comprehensive parks, large parks, and water-themed parks had significantly lower LSTs. The VCI significantly influenced LST in autumn, with trees having a stronger cooling effect than shrubs. LMs showed a more prominent effect than VCIs on LST during spring, summer, and winter. Parks with longer perimeters, larger and more dispersed green patches, higher plant species richness, higher vegetation heights, and larger canopies were associated with more efficient thermal reduction in an urban setting. The novelty of this study lies in its detailed analysis of the seasonal thermal regulation effects of different types of urban parks, providing new insights for more effective urban greenspace planning and management. Our findings assist urban managers in mitigating the urban surface heat effect through more effective urban greenspace planning, vegetation community design, and maintenance, thereby enhancing cities’ potential resilience to climate change. Full article
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<p>Location of Zhengzhou city, Henan, China. (<b>a</b>) Distribution of 123 selected parks in the study area versus 805 sampling points, (<b>b</b>–<b>f</b>) Distribution of sample sites in selected parks, (<b>b’</b>–<b>f’</b>) Selected parkland classification results.</p>
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<p>Flowchart of this study.</p>
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<p>(<b>a</b>–<b>d</b>) LST in different seasons (Units: °C); (<b>e</b>–<b>h</b>) Land surface temperature of parks in different seasons.</p>
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<p>Differences in LST categories among parks in different seasons. The letters a, b, and c denote significant disparities identified via Fisher’s least significant difference test (<span class="html-italic">p</span> &lt; 0.05) across various park types during different seasons. (<b>a</b>–<b>c</b>), (<b>d</b>–<b>f</b>), (<b>g</b>–<b>i</b>), and (<b>j</b>–<b>l</b>) represent the LST distribution of parks classified by different standards in spring, summer, autumn, and winter, respectively.</p>
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<p>Analysis of the differences in driving factors among different park types. The letters a, b, and c denote significant disparities identified via Fisher’s least significant difference test (<span class="html-italic">p</span> &lt; 0.05) among different park types. (<b>a</b>–<b>o</b>) are vegetation characteristic indices, and (<b>p</b>–<b>y</b>) are landscape pattern indices.</p>
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<p>Spearman correlation coefficients of influencing factors with LST across seasons. (**. Correlation is significant at the 0.01 level; *. Correlation is significant at the 0.05 level).</p>
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<p>Relative contribution of each influencing factor to surface temperature under different seasons.</p>
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<p>Relative importance of different park types for surface temperature in different seasons (%).</p>
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<p>Partial dependence plot of the driving factors’ impact on LST.</p>
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<p>The correlation between each driving factor and LST in different park types and seasons.</p>
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20 pages, 2679 KiB  
Article
Spatio-Temporal Analysis of Green Infrastructure along the Urban-Rural Gradient of the Cities of Bujumbura, Kinshasa and Lubumbashi
by Henri Kabanyegeye, Nadège Cizungu Cirezi, Héritier Khoji Muteya, Didier Mbarushimana, Léa Mukubu Pika, Waselin Salomon, Yannick Useni Sikuzani, Kouagou Raoul Sambieni, Tatien Masharabu and Jan Bogaert
Land 2024, 13(9), 1467; https://doi.org/10.3390/land13091467 - 10 Sep 2024
Viewed by 153
Abstract
This study analyses the dynamics of green infrastructure (GI) in the cities of Bujumbura, Kinshasa, and Lubumbashi. A remote sensing approach, combined with landscape ecology metrics, characterized this analysis, which was based on three Landsat images acquired in 2000, 2013, and 2022 for [...] Read more.
This study analyses the dynamics of green infrastructure (GI) in the cities of Bujumbura, Kinshasa, and Lubumbashi. A remote sensing approach, combined with landscape ecology metrics, characterized this analysis, which was based on three Landsat images acquired in 2000, 2013, and 2022 for each city. Spatial pattern indices reveal that GI was suppressed in Bujumbura and Kinshasa, in contrast to Lubumbashi, which exhibited fragmentation. Furthermore, the values of stability, aggregation, and fractal dimension metrics suggest that Bujumbura experienced rather intense dynamics and a reduction in the continuity of its GI, while Kinshasa showed weaker dynamics and tendencies towards patch aggregation during the study period. In contrast, Lubumbashi exhibited strong dynamics and aggregation of its GI within a context of significant anthropization. The evolution of the Normalized Difference Vegetation Index demonstrates a sawtooth pattern in the evolution of tall vegetation patches in Bujumbura, compared to a gradual decrease in Kinshasa and Lubumbashi. It is recommended that urban growth in these cities should be carefully planned to ensure the integration of sufficient GI. Full article
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<p>Bujumbura is located in Burundi and Kinshasa, and Lubumbashi is in the Democratic Republic of the Congo.</p>
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<p>Land use maps of Bujumbura (Burundi), Kinshasa, and Lubumbashi (DRC) from supervised classification of Landsat images from 2000, 2013, and 2022 based on the Random Forest algorithm.</p>
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<p>Trends in number of patches, total area, average patch area, and vegetation class dominance for the cities of Bujumbura (Burundi), Kinshasa, and Lubumbashi (DRC) for the years 2000, 2013, and 2022.</p>
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<p>Normalized difference vegetation maps of the cities of Bujumbura (Burundi) (<b>A</b>), Kinshasa (<b>B</b>), and Lubumbashi (DRC) (<b>C</b>) for the years 2020, 2013, and 2022.</p>
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<p>Proportions of GI areas over NDVI intervals were found for the cities of Bujumbura, Kinshasa, and Lubumbashi for the years 2000, 2013, and 2022.</p>
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17 pages, 4369 KiB  
Article
A Multi-Hazard Approach to Climate Migration: Testing the Intersection of Climate Hazards, Population Change, and Location Desirability from 2000 to 2020
by Zachary M. Hirsch, Jeremy R. Porter, Jasmina M. Buresch, Danielle N. Medgyesi, Evelyn G. Shu and Matthew E. Hauer
Climate 2024, 12(9), 140; https://doi.org/10.3390/cli12090140 - 7 Sep 2024
Viewed by 346
Abstract
Climate change intensifies the frequency and severity of extreme weather events, profoundly altering demographic landscapes globally and within the United States. This study investigates their impact on migration patterns, using propensity score matching and LASSO techniques within a larger regression modeling framework. Here, [...] Read more.
Climate change intensifies the frequency and severity of extreme weather events, profoundly altering demographic landscapes globally and within the United States. This study investigates their impact on migration patterns, using propensity score matching and LASSO techniques within a larger regression modeling framework. Here, we analyze historical population trends in relation to climate risk and exposure metrics for various hazards. Our findings reveal nuanced patterns of climate-induced population change, including “risky growth” areas where economic opportunities mitigate climate risks, sustaining growth in the face of observed exposure; “tipping point” areas where the amenities are slowly giving way to the disamenity of escalating hazards; and “Climate abandonment” areas experiencing exacerbated out-migration from climate risks, compounded by other out-migration market factors. Even within a single county, these patterns vary significantly, underscoring the importance of localized analyses. Projecting population impacts due to climate risk to 2055, flood risks are projected to impact the largest percentage of areas (82.6%), followed by heatwaves (47.4%), drought (46.6%), wildfires (32.7%), wildfire smoke (21.7%), and tropical cyclone winds (11.1%). The results underscore the importance of understanding hyperlocal patterns of risk and change in order to better forecast future patterns. Full article
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<p>Census block group relative population change from years 2000 to 2020 (%).</p>
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<p>County-level projected population change resulting from the combined climate effect over the next 30 years.</p>
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<p>County-level projected population change (%) resulting from the combined climate effect, socioeconomic impact under SSP2, and population redistribution due to climate migration over the next 30 years.</p>
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<p>Population projection trends in Miami-Dade County neighborhoods for areas of continual growth (blue), risky growth with tipping points (gray), and climate abandonment (red).</p>
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<p>Miami-Dade County block groups’ combined climate effect and projected population trend designation (risky growth, tipping point, or climate abandonment area).</p>
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18 pages, 4769 KiB  
Article
Use of Telemetry Data to Quantify Life History Diversity in Migrating Juvenile Chinook Salmon (Oncorhynchus tshawytscha)
by Pascale Ava Lake Goertler, Myfanwy Johnston, Cyril Joseph Michel, Tracy Grimes, Gabriel Singer, Jeremy Notch and Ted Sommer
Water 2024, 16(17), 2529; https://doi.org/10.3390/w16172529 - 6 Sep 2024
Viewed by 346
Abstract
Variations in species distribution, population structure, and behavior can provide a portfolio effect that buffers populations against rapid environmental change. Although diversity has been identified as a goal for effective resource management and genetic and demographic tools have been developed, life history remains [...] Read more.
Variations in species distribution, population structure, and behavior can provide a portfolio effect that buffers populations against rapid environmental change. Although diversity has been identified as a goal for effective resource management and genetic and demographic tools have been developed, life history remains challenging to quantify. In this study, we demonstrate a novel metric of life history diversity using telemetry data from migratory fish. Here, we examined diversity in the outmigration behavior of juvenile Chinook salmon (Oncorhynchus tshawytscha) released in the Sacramento River, California, between 2007 and 2017. In this synthesis, we examined a wide variety of landscape and demographic drivers at high resolution by incorporating many individual telemetry studies, with variability in release location by year, environmental conditions, and all runs of salmon that are present in the watershed. When years were grouped by shared hydrologic conditions, variation in travel time was significantly higher in wet years. Further, our model showed a negative effect of warm temperatures at low flows on the variation in migration movements. This suggests that enhanced hydrologic connectivity increases the variation in migration time, a representation of habitat complexity and biocomplexity, despite the degraded state of this watershed and the weakened state of these populations. Variation in migration behavior could buffer species from current and future environmental changes, such as climate effects on precipitation and temperature. Hence, behavioral metrics generated from telemetry studies can be used to understand life history diversity and the potential effects of environmental fluctuations. Full article
(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)
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<p>(<b>A</b>) Map of North America, with the location of California’s Central Valley. (<b>B</b>) Map of fish release and receiver locations for individual studies synthesized here (<a href="#app1-water-16-02529" class="html-app">Supplementary S2, Table S1</a>), colored by technology type, as well as release groups from Johnson et al. [<a href="#B42-water-16-02529" class="html-bibr">42</a>]. (<b>C</b>) Map of routes and locations used for the routing analysis denoted by color and labels, respectively. Labels for locations of data collection describing environmental conditions are marked by *.</p>
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<p>(<b>A</b>) Box plot of the standard deviation in travel time (days) to the estuary, grouped by the water year type in which juvenile Chinook salmon were released (Sacramento Valley water year index); and (<b>B</b>) the standard deviation in travel time (days) grouped by release year and location (the upper Sacramento River, the middle Sacramento River, and the Tidal Delta, from Johnson et al. [<a href="#B42-water-16-02529" class="html-bibr">42</a>] plotted against the number of routes used. The box plot displays the distribution of the data based on a five-number summary: the minimum (the lowest horizontal line), the first quartile (the bottom of gray box), the median (the thick line), the third quartile (the top of gray box), and the maximum (the highest horizontal line).</p>
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<p>(<b>A</b>) Mean daily Sacramento River outflow (cfs) and (<b>B</b>) water temperature between 2007 and 2017. Black symbols represent the conditions, when tagged fish were present.</p>
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<p>Data and partial residuals from the best hierarchical generalized additive model, which included release group (symbol), the mean in daily water temperature, and the mean in daily outflow of the Sacramento River between the release and the first detection in the estuary for each individual fish. The global smoother is shown here, while plots for each group-level smoother are in <a href="#app1-water-16-02529" class="html-app">Supplemental Materials (Supplementary S7; Figure S1)</a>. This plot shows the relationship between water temperature and the standard deviation in individual daily detection time series (spread in individual daily travel distances) while adjusting for the influence of outflow. Solid grey represents no data.</p>
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31 pages, 2905 KiB  
Article
Ranking of 10 Global One-Arc-Second DEMs Reveals Limitations in Terrain Morphology Representation
by Peter L. Guth, Sebastiano Trevisani, Carlos H. Grohmann, John Lindsay, Dean Gesch, Laurence Hawker and Conrad Bielski
Remote Sens. 2024, 16(17), 3273; https://doi.org/10.3390/rs16173273 - 3 Sep 2024
Viewed by 649
Abstract
At least 10 global digital elevation models (DEMs) at one-arc-second resolution now cover Earth. Comparing derived grids, like slope or curvature, preserves surface spatial relationships, and can be more important than just elevation values. Such comparisons provide more nuanced DEM rankings than just [...] Read more.
At least 10 global digital elevation models (DEMs) at one-arc-second resolution now cover Earth. Comparing derived grids, like slope or curvature, preserves surface spatial relationships, and can be more important than just elevation values. Such comparisons provide more nuanced DEM rankings than just elevation root mean square error (RMSE) for a small number of points. We present three new comparison categories: fraction of unexplained variance (FUV) for grids with continuous floating point values; accuracy metrics for integer code raster classifications; and comparison of stream channel vector networks. We compare six global DEMs that are digital surface models (DSMs), and four edited versions that use machine learning/artificial intelligence techniques to create a bare-earth digital terrain model (DTM) for different elevation ranges: full Earth elevations, under 120 m, under 80 m, and under 10 m. We find edited DTMs improve on elevation values, but because they do not incorporate other metrics in their training they do not improve overall on the source Copernicus DSM. We also rank 17 common geomorphic-derived grids for sensitivity to DEM quality, and document how landscape characteristics, especially slope, affect the results. None of the DEMs perform well in areas with low average slope compared to reference DTMs aggregated from 1 m airborne lidar data. This indicates that accurate work in low-relief areas grappling with global climate change should use airborne lidar or very high resolution image-derived DTMs. Full article
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<p>Test areas and the elevation ranges where they have data.</p>
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<p>Average ranks for the difference distribution and FUV criteria and evaluations of the FUV criteria for average slope, average roughness, percentage of tile barren, and percentage forested.</p>
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<p>CopDEM win/loss record for difference distribution criteria. Solid color wins, white ties, and cross-hatch losses. Criteria defined by [<a href="#B17-remotesensing-16-03273" class="html-bibr">17</a>].</p>
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<p>Best evaluation percentiles versus the FUV for all criteria used in the study, for all tiles and 5 filters. DEM performance increases to the right. The best/easiest criteria to match are listed in order from the top of the legend. Criteria names given in <a href="#remotesensing-16-03273-t004" class="html-table">Table 4</a>.</p>
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<p>FUV for three criteria, sorted by the best tile evaluations for four test DEMs; for all seven test DEMs see <a href="#app1-remotesensing-16-03273" class="html-app">Figure S8</a>.</p>
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<p>Effect of tile slope and percent barren on the best evaluation from the test DEMs on 3 FUV criteria. Number of tiles indicated for each category.</p>
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<p>CopDEM head-to-head comparison to other test DEMs for the FULL elevation range, FUV criteria. Solid color wins, white ties, and cross-hatch (which may appear just as a light color) losses. Criteria names given in <a href="#remotesensing-16-03273-t004" class="html-table">Table 4</a>.</p>
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<p>Average evaluations for the raster classification and channel mismatch criteria.</p>
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<p>Clusters for FULL-elevation-range FUV criteria, with the number of tiles in each cluster. Criteria names given in <a href="#remotesensing-16-03273-t004" class="html-table">Table 4</a>.</p>
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<p>Cluster characteristics for CopDEM, with single points showing outliers. Colors for the clusters are the same as in the previous section. The box extent includes the 25th to the 75th percentiles, the middle line shows the mean, the whiskers go from the 5th to the 95th percentiles, and the data points show outliers.</p>
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<p>Location of tiles in each of the cluster groups.</p>
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<p>Test DEM comparisons to CopDEM for all FUV criteria for the U10, U80, U120, and FULL elevation range. <a href="#app1-remotesensing-16-03273" class="html-app">Supplementary figures</a> use FABDEM (<a href="#app1-remotesensing-16-03273" class="html-app">Figure S9</a>) and CoastalDEM (<a href="#app1-remotesensing-16-03273" class="html-app">Figure S10</a>) as the base comparison. Solid color wins, white ties, and cross-hatch (which may appear just as a light color) losses. Criteria names given in <a href="#remotesensing-16-03273-t004" class="html-table">Table 4</a>.</p>
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<p>FUV criteria performance for all elevation ranges. Criteria names given in <a href="#remotesensing-16-03273-t004" class="html-table">Table 4</a>.</p>
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<p>FUV results for all elevation ranges.</p>
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<p>Average evaluations by slope category for the FULL elevation, U120, U80, and U10 data sets.</p>
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<p>Edited DTM changes to CopDEM on barren coast of southwest Africa, with the CopDEM hillshade and the GLCS LC100 land cover. Differences greater than 1 m highlighted.</p>
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<p>Slope for FUV for three representative criteria for four best test DEMs. Criteria names given in <a href="#remotesensing-16-03273-t004" class="html-table">Table 4</a>.</p>
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30 pages, 6660 KiB  
Article
Beyond Barriers: Constructing the Cloud Migration Complexity Index for China’s Digital Transformation
by Weiwei Wen, Chenglei Zhang and Qin Ye
J. Theor. Appl. Electron. Commer. Res. 2024, 19(3), 2239-2268; https://doi.org/10.3390/jtaer19030109 - 3 Sep 2024
Viewed by 311
Abstract
In the digital era, cloud computing stands as a pivotal tool in the transformative journey of enterprises, with China’s tech landscape serving as a prime exemplar. However, when enterprises embrace cloud computing, they face complex hurdles, mainly technical ones. To understand how the [...] Read more.
In the digital era, cloud computing stands as a pivotal tool in the transformative journey of enterprises, with China’s tech landscape serving as a prime exemplar. However, when enterprises embrace cloud computing, they face complex hurdles, mainly technical ones. To understand how the complexity of cloud migration affects their digital transformation, our research meticulously constructed business process models for business deployment in both non-cloud and cloud contexts, spanning the IaaS, PaaS, and SaaS levels. By harnessing China’s public cloud market data, we constructed the Cloud Migration Complexity Index, providing a tangible metric to gauge the intricacies of cloud migration and their implications on digital transformation. The findings illustrate that a decrease in cloud migration complexity significantly accelerates digital transformation, with the reduction in SaaS complexity having the most profound impact. Analyzing businesses of varying scales, the diminishing complexity of SaaS predominantly boosts digital transformation for non-SME enterprises, while reduced PaaS complexity is most beneficial for SMEs. This study advocates for the government to expand the PaaS market and suggest that cloud providers develop more PaaS-based products to optimize cloud migration both technically and economically. Full article
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<p>Cloud service model deployment level.</p>
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<p>Standard deployment model.</p>
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<p>BPMN for business deployment based on non-cloud.</p>
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<p>BPMN for business deployment based on IaaS.</p>
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<p>BPMN for business deployment based on PaaS.</p>
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<p>BPMN for business deployment based on SaaS.</p>
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<p>BPMN for business deployment based on non-cloud after splitting.</p>
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<p>BPMN for business deployment based on IaaS after splitting.</p>
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<p>BPMN for business deployment based on non-cloud after assignment. Each task is labeled with a task-id, with the criteria for its TW assignment detailed in <a href="#jtaer-19-00109-t0A1" class="html-table">Table A1</a> of <a href="#app1-jtaer-19-00109" class="html-app">Appendix A</a>.</p>
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<p>BPMN for business deployment based on IaaS after assignment. Each task is labeled with a task-id, with the criteria for its TW assignment detailed in <a href="#jtaer-19-00109-t0A2" class="html-table">Table A2</a> of <a href="#app1-jtaer-19-00109" class="html-app">Appendix A</a>.</p>
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<p>BPMN for business deployment based on PaaS after assignment. Each task is labeled with a task-id, with the criteria for its TW assignment detailed in <a href="#jtaer-19-00109-t0A3" class="html-table">Table A3</a> of <a href="#app1-jtaer-19-00109" class="html-app">Appendix A</a>.</p>
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<p>BPMN for business deployment based on SaaS after assignment. Each task is labeled with a task-id, with the criteria for its TW assignment detailed in <a href="#jtaer-19-00109-t0A4" class="html-table">Table A4</a> of <a href="#app1-jtaer-19-00109" class="html-app">Appendix A</a>.</p>
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<p>Conversion of tasks after assignment TW to general task.</p>
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<p>The market size of China’s public cloud. Data source: Cloud Computing White Paper 2016, Cloud Computing Development White Paper 2018, Cloud Computing White Paper 2022.</p>
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<p>The cloud migration complexity index measurement results.</p>
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11 pages, 1199 KiB  
Article
Dietary Shift in a Barn Owl (Tyto alba) Population Following Partial Abandonment of Cultivated Fields (Central Apennine Hills, Italy)
by Gabriele Achille, Dan Gafta, Csaba Szabó, Fadia Canzian and Nazzareno Polini
Animals 2024, 14(17), 2562; https://doi.org/10.3390/ani14172562 - 3 Sep 2024
Viewed by 252
Abstract
While most studies focused on the impact of intensive agriculture on the barn owl’s diet, little is known about the effect of cropland abandonment. We compared the taxon composition/evenness and feeding guild structure of small mammal prey identified in pellets collected before (2004) [...] Read more.
While most studies focused on the impact of intensive agriculture on the barn owl’s diet, little is known about the effect of cropland abandonment. We compared the taxon composition/evenness and feeding guild structure of small mammal prey identified in pellets collected before (2004) and after (2012) the abandonment of 9% of cultivated fields within a cultural landscape. Data on prey abundance per pellet were analysed through non-metric multidimensional scaling and permutational, paired tests. Prey taxon evenness in 2012 was significantly lower than in 2004. That induced a shift in prey taxon composition as indicated by the significantly lower dietary similarity compared with the random expectation. The increasing and declining abundance of Murinae and Crocidurinae, respectively, had the largest contribution to the differentiation of the diet spectrum. Insectivorous prey was significantly more abundant in 2004 compared to 2012, while the opposite was true for omnivorous prey. Our results suggest that even a small fraction of abandoned crops in the landscape might induce a detectable shift in the barn owl’s food niche. The dietary effects are similar to those observed after agricultural intensification, that is, an increase in the abundance of generalists to the detriment of specialist mammal prey. Full article
(This article belongs to the Section Ecology and Conservation)
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<p>Map of the study area (red quadrat) showing the cultivated fields in 2004 (purple polygons) and the subsequently abandoned fields in 2012 (yellow polygons). The location of the owls’ roost, where the pellets were collected, is marked by the red balloon sign.</p>
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<p>Ordination of prey taxa based on their abundance in pellets collected in 2004 and 2012 (NMDS final stress = 8.476 × 10<sup>−6</sup>).</p>
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<p>Abundance distribution of prey-feeding guilds in the years 2004 and 2012. Pairs of the same and different letters refer to non-significant and, respectively, significant differences between the two surveys.</p>
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46 pages, 3730 KiB  
Article
Performance Evaluation of CF-MMIMO Wireless Systems Using Dynamic Mode Decomposition
by Freddy Pesantez Diaz and Claudio Estevez
Telecom 2024, 5(3), 846-891; https://doi.org/10.3390/telecom5030043 - 2 Sep 2024
Viewed by 497
Abstract
Cell-Free Massive Multiple-Input–Multiple-Output (CF-MIMO) systems have transformed the landscape of wireless communication, offering unparalleled enhancements in Spectral Efficiency and interference mitigation. Nevertheless, the large-scale deployment of CF-MIMO presents significant challenges in processing signals in a scalable manner. This study introduces an innovative methodology [...] Read more.
Cell-Free Massive Multiple-Input–Multiple-Output (CF-MIMO) systems have transformed the landscape of wireless communication, offering unparalleled enhancements in Spectral Efficiency and interference mitigation. Nevertheless, the large-scale deployment of CF-MIMO presents significant challenges in processing signals in a scalable manner. This study introduces an innovative methodology that leverages the capabilities of Dynamic Mode Decomposition (DMD) to tackle the complexities of Channel Estimation in CF-MIMO wireless systems. By extracting dynamic modes from a vast array of received signal snapshots, DMD reveals the evolving characteristics of the wireless channel across both time and space, thereby promising substantial improvements in the accuracy and adaptability of channel state information (CSI). The efficacy of the proposed methodology is demonstrated through comprehensive simulations, which emphasize its superior performance in highly mobile environments. For performance evaluation, the most common techniques have been employed, comparing the proposed algorithms with traditional methods such as MMSE (Minimum Mean Squared Error), MRC (Maximum Ration Combining), and ZF (Zero Forcing). The evaluation metrics used are standard in the field, namely the Cumulative Distribution Function (CDF) and the average UL/DL Spectral Efficiency. Furthermore, the study investigates the impact of DMD-enabled Channel Estimation on system performance, including beamforming strategies, spatial multiplexing within realistic time- and delay-correlated channels, and overall system capacity. This work underscores the transformative potential of incorporating DMD into massive MIMO wireless systems, advancing communication reliability and capacity in increasingly dynamic and dense wireless environments. Full article
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<p>CF-MMIMO system [<a href="#B19-telecom-05-00043" class="html-bibr">19</a>]. Each color represents a dynamically formed user-centric cell.</p>
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<p>Communication blocks in the time–frequency plane. There appear uplink data pilots (<math display="inline"><semantics> <msub> <mi>τ</mi> <mi>p</mi> </msub> </semantics></math>) and uplink (<math display="inline"><semantics> <msub> <mi>τ</mi> <mi>u</mi> </msub> </semantics></math>) and downlink data.</p>
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<p>A random realization of the proposed scenarios. APs are located randomly within the circle of radius R, and the paths followed by each UE are shown with different colors.</p>
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<p>Propagation illustration and the multi-path sources.</p>
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<p>The formation of the <math display="inline"><semantics> <msub> <mo>Φ</mo> <mi>k</mi> </msub> </semantics></math> matrix involves <span class="html-italic">n</span> pilots and <span class="html-italic">k</span> consecutive samples. (<b>A</b>) Time–frequency snapshot Number 1. Pilots are show as red squares. (<b>B</b>) <span class="html-italic">k</span> time frequency snapshots. Each column of matrix <math display="inline"><semantics> <msub> <mo>Φ</mo> <mi>k</mi> </msub> </semantics></math> is formed by <span class="html-italic">k</span> consecutive pilot samples.</p>
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<p>Norm of the entries of matrix <span class="html-italic">R</span>.</p>
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<p>Normalized eigenvalue of the empirical matrix <span class="html-italic">R</span>. The red circle encloses a small group of eigenvalues that are significantly more representative in magnitude than the rest.</p>
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<p>Norm of entries of an empirical correlation matrix.</p>
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<p>Norm of entries ofthe empirical correlation matrix applied to DMD.</p>
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<p>PiDMD is used to obtain a Toeplitz matrix from empirical data.</p>
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<p>The matrix <math display="inline"><semantics> <mi mathvariant="bold">R</mi> </semantics></math> obtained from empirical data through the successive application of DMD and PiDMD.</p>
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<p>Structure of the R correlation matrix after sequentially applying DMD and mpeDMD to empirical data. mpeDMD is able to detect the Toeppliz form of the R matrix.</p>
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<p>The matrix <math display="inline"><semantics> <mi mathvariant="bold">R</mi> </semantics></math> matrix is presented with varying numbers of antennas to highlight its effect on the phenomenon known as <span class="html-italic">channel hardening</span>. PiDMD is used.</p>
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<p>The matrix <math display="inline"><semantics> <mi mathvariant="bold">R</mi> </semantics></math> is presented with varying numbers of pilots to highlight its effect on the phenomenon known as <span class="html-italic">favorable propagation</span>. mpeDMD is used.</p>
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<p>Downlink CDF of the per-user SE for non-coherent transmission with full power with <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>d</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>=</mo> <mn>0.0005</mn> </mrow> </semantics></math> (X-scale in the graphs are scaled by <math display="inline"><semantics> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics></math>).</p>
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<p>CDF of UL SE for <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>τ</mi> <mi>p</mi> </msub> <mo>=</mo> <mn>5</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mo>[</mo> <mn>10</mn> <mo>,</mo> <mn>40</mn> <mo>]</mo> </mrow> </semantics></math>. (<b>A</b>) MR, MR-mpeDMD, and MR-PiDMD is shown for <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>40</mn> </mrow> </semantics></math>. (<b>B</b>) MMSE, MMSE-mpeDMD, and MMSE-PiDMD is shown for <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>40</mn> </mrow> </semantics></math>. (<b>C</b>) ZF, ZF-mpeDMD, and ZF-PiDMD is shown for <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>40</mn> </mrow> </semantics></math>. (<b>D</b>) PZFZ, PZFZ-mpeDMD, and PFZF-PiDMD is shown for <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>40</mn> </mrow> </semantics></math>.</p>
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<p>The average uplink SE per UE as a function of pilot sequence length, <math display="inline"><semantics> <msub> <mi>τ</mi> <mi>p</mi> </msub> </semantics></math>, We consider <span class="html-italic">L</span> = 100, <span class="html-italic">N</span> = 4, <span class="html-italic">K</span> = 40, and spatially correlated Rayleigh fading with ASD <math display="inline"><semantics> <mrow> <msub> <mi>σ</mi> <mi>ϕ</mi> </msub> <mo>=</mo> <msub> <mi>σ</mi> <mi>θ</mi> </msub> <mo>=</mo> <mn>15</mn> <mi>°</mi> </mrow> </semantics></math>.</p>
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<p>The relative error of the average SE achieved by the asymptotic closed-form expression versus the number of UEs, with <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mi>K</mi> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>64</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>τ</mi> <mi>p</mi> </msub> <mo>=</mo> <mi>K</mi> <mo>/</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mn>50</mn> <mo>≤</mo> <mi>v</mi> <mo>≤</mo> <mn>150</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>p</mi> <mi>k</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math> mW for each UE.</p>
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<p>Channel prediction algorithm comparison: Machine Learning, Kalman Filter, mpeDMD, and PiDMD.</p>
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<p>The average uplink Spectral Efficiency (SE) per User Equipment (UE) as a function of the angular spread (ASD) for azimuth and elevation angles, where <math display="inline"><semantics> <mrow> <msub> <mi>σ</mi> <mi>ϕ</mi> </msub> <mo>=</mo> <msub> <mi>σ</mi> <mi>θ</mi> </msub> </mrow> </semantics></math>, is analyzed for different operations of CF-MMIMO and small-cell systems. We consider <math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>M</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>40</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <msub> <mi>τ</mi> <mi>p</mi> </msub> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math>. The results for uncorrelated Rayleigh fading are included as a reference.</p>
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<p>Varying data frame length and non-coherent transmission (<span class="html-italic">L</span> = 100, <span class="html-italic">K</span> = 20, <span class="html-italic">N</span> = 2, ASD = 30°).</p>
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<p>Average UL SE vs. number of <math display="inline"><semantics> <msub> <mi>τ</mi> <mi>p</mi> </msub> </semantics></math>, centralized LSFD (<span class="html-italic">L</span> = 100, <span class="html-italic">K</span> = 20, <span class="html-italic">N</span> = 2, ASD = 30°).</p>
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<p>CDF of median SE and 95% likely per-user uplink transmission with full power and <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>d</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>=</mo> <mrow> <mo>[</mo> <mn>0</mn> <mo>,</mo> <mn>0.002</mn> <mo>]</mo> </mrow> </mrow> </semantics></math> (X-scale in Graphs are scaled by <math display="inline"><semantics> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics></math>). (<b>A</b>) Uplink CDF of different Channel Estimation techniques (<math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, ASD = 30°, <math display="inline"><semantics> <mrow> <mn>50</mn> <mo>&lt;</mo> <mi>v</mi> <mo>&lt;</mo> <mn>150</mn> </mrow> </semantics></math>). (<b>B</b>) 95%-likely per-user uplink SE vs. <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>D</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> </mrow> </semantics></math> (<math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, ASD = 30°, <math display="inline"><semantics> <mrow> <mn>50</mn> <mo>&lt;</mo> <mi>v</mi> <mo>&lt;</mo> <mn>150</mn> </mrow> </semantics></math>). (X-axis scale multiplied by <math display="inline"><semantics> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics></math>).</p>
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<p>CDF of the per-user downlink SE for coherent and non-coherent transmission with full power with <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>d</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>d</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>=</mo> <mn>0.0005</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>d</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>=</mo> <mn>0.001</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>d</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>=</mo> <mn>0.0015</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mn>0.002</mn> </mrow> </semantics></math> (X-scale in the graphs are multiplied by <math display="inline"><semantics> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics></math>). (<b>A</b>) The 95%-likely per-user coherent downlink Spectral Efficiency (SE) against the value of <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>D</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> </mrow> </semantics></math> for coherent transmission (<math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>ASD</mi> <mo>=</mo> <msup> <mn>30</mn> <mo>∘</mo> </msup> </mrow> </semantics></math>). (<b>B</b>) The 95%-likely per-user non-coherent downlink Spectral Efficiency (SE) against the value of <math display="inline"><semantics> <mrow> <msub> <mi>f</mi> <mi>D</mi> </msub> <msub> <mi>T</mi> <mi>s</mi> </msub> </mrow> </semantics></math> for non-coherent transmission (<math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>20</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>2</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>ASD</mi> <mo>=</mo> <msup> <mn>30</mn> <mo>∘</mo> </msup> </mrow> </semantics></math>).</p>
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<p>Average SE per UE against L (number of APs), with <math display="inline"><semantics> <mrow> <msub> <mi>τ</mi> <mi>p</mi> </msub> <mo>=</mo> <mn>7</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>10</mn> </mrow> </semantics></math>, <span class="html-italic">N</span> = 8 and <math display="inline"><semantics> <msub> <mi>p</mi> <mi>k</mi> </msub> </semantics></math> = 100 mW for each UE.</p>
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<p>CDF of UL sum SE for <math display="inline"><semantics> <mrow> <mi>K</mi> <mo>=</mo> <mn>50</mn> </mrow> </semantics></math> as a function of the number of AP antennas for different channel estimators.</p>
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<p>Average UL SE[bits/s/Hz] vs. number of time–frequency snapshots <math display="inline"><semantics> <msub> <mi>τ</mi> <mi>p</mi> </msub> </semantics></math>.</p>
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17 pages, 2186 KiB  
Article
Spatial Modeling of Insect Pollination Services in Fragmented Landscapes
by Ehsan Rahimi and Chuleui Jung
Insects 2024, 15(9), 662; https://doi.org/10.3390/insects15090662 - 30 Aug 2024
Viewed by 495
Abstract
Pollination mapping and modeling have opened new avenues for comprehending the intricate interactions between pollinators, their habitats, and the plants they pollinate. While the Lonsdorf model has been extensively employed in pollination mapping within previous studies, its conceptualization of bee movement in agricultural [...] Read more.
Pollination mapping and modeling have opened new avenues for comprehending the intricate interactions between pollinators, their habitats, and the plants they pollinate. While the Lonsdorf model has been extensively employed in pollination mapping within previous studies, its conceptualization of bee movement in agricultural landscapes presents notable limitations. Consequently, a gap exists in exploring the effects of forest fragmentation on pollination once these constraints are addressed. In this study, our objective is to model pollination dynamics in fragmented forest landscapes using a modified version of the Lonsdorf model, which operates as a distance-based model. Initially, we generated several simulated agricultural landscapes, incorporating forested and agricultural habitats with varying forest proportions ranging from 10% to 50%, along with a range of fragmentation degrees from low to high. Subsequently, employing the modified Lonsdorf model, we evaluated the nesting suitability and consequent pollination supply capacity across these diverse scenarios. We found that as the degree of forest fragmentation increases, resulting in smaller and more isolated patches with less aggregation, the pollination services within landscapes tend to become enhanced. In conclusion, our research suggests that landscapes exhibiting fragmented forest patch patterns generally display greater nesting suitability due to increased floral resources in their vicinity. These findings highlight the importance of employing varied models for pollination mapping, as modifications to the Lonsdorf model yield distinct outcomes compared to studies using the original version. Full article
(This article belongs to the Special Issue Insect Pollinators and Pollination Service Provision)
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<p>Simulated landscapes in different forest proportions (black patches) and degree of fragmentation.</p>
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<p>Examples of simulated landscapes after assigning bees and flowers to cells. Cells with a value of 1 represent forested areas, depicted by the brown color. Conversely, cells designated as farm cells receive a random value between 0 and 0.9. A value of 0 indicates the absence of floral resources, whereas a value of 0.9 signifies the highest desirability of floral resources for bees.</p>
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<p>Predicted pollination outcomes utilizing the modified Lonsdorf model amidst diverse fragmentation and forest proportion patterns. In the first column (<b>A</b>), the original landscapes are depicted, where green patches represent forest patches. The subsequent column (<b>B</b>) illustrates the fitness of these patches based on surrounding floral resources. The third column (<b>C</b>) presents the final pollination maps, spanning the entire landscape and employing a 5 by 5 window. The rows in the figure illustrate variations in forest proportion and the degree of fragmentation. It is important to note that these landscapes were chosen merely as examples to demonstrate the concept.</p>
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<p>Sum of nesting suitability values for each landscape at different forest fragmentation and proportions.</p>
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<p>Sum of pollination service values for each landscape at different forest fragmentation and proportions.</p>
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<p>Behavior of the number of patches (NP) metric in different forest proportions and fragmentation.</p>
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<p>Behavior of aggregation (AI) metric in different forest proportions and fragmentation.</p>
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24 pages, 49494 KiB  
Article
Meta-Connectivity in Urban Morphology: A Deep Generative Approach for Integrating Human–Wildlife Landscape Connectivity in Urban Design
by Sheng-Yang Huang, Yuankai Wang, Enriqueta Llabres-Valls, Mochen Jiang and Fei Chen
Land 2024, 13(9), 1397; https://doi.org/10.3390/land13091397 - 30 Aug 2024
Viewed by 261
Abstract
Traditional urban design often overlooks the synchronisation of human and ecological connectivities, typically favouring corridors for ecological continuity. Our study challenges this convention by introducing a computational design approach, meta-connectivity, leveraging the deep generative models performing cross-domain translation to integrate human–wildlife landscape connectivity [...] Read more.
Traditional urban design often overlooks the synchronisation of human and ecological connectivities, typically favouring corridors for ecological continuity. Our study challenges this convention by introducing a computational design approach, meta-connectivity, leveraging the deep generative models performing cross-domain translation to integrate human–wildlife landscape connectivity in urban morphology amidst the planetary urbanisation. Utilising chained Pix2Pix models, our research illustrates a novel meta-connectivity design reasoning framework, combining landscape connectivity modelling with conditional reasoning based on deep generative models. This framework enables the adjustment of both human and wildlife landscape connectivities based on their correlative patterns in one single design process, guiding the rematerialisation of urban landscapes without the need for explicit prior ecological or urban data. Our empirical study in East London demonstrated the framework’s efficacy in suggesting wildlife connectivity adjustments based on human connectivity metrics. The results demonstrate the feasibility of creating an innovative urban form in which the land cover guided by the connectivity gradients replaces the corridors based on simple geometries. This research thus presents a methodology shift in urban design, proposing a symbiotic approach to integrating disparate yet interrelated landscape connectivities within urban contexts. Full article
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<p>An overview of the proposed design reasoning framework.</p>
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<p>A map of the study area illustrating the geospatial location and land use characteristics.</p>
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<p>(<b>a</b>) The current wildlife landscape connectivity (LCw) mapping and (<b>b</b>) the HOG analysis output of the current connectivity of the site (the coloured area) and the surrounding. A large number of linear features, particularly in the east–west orientation, were detected due to the extensive use of corridors in the area.</p>
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<p>(<b>a</b>) The overall connectivity (Cm) on wildlife (left half) and human connectivity (right half) datasets; (<b>b</b>) The kernel vitality (Vk) on the wildlife data within NBI and eBird datasets; (<b>c</b>) a box plot of NBI and eBird wildlife landscape connectivity (LCw) HOG variance.</p>
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<p>The presentation of NBI and eBird dataset.</p>
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<p>Architecture of the Pix2Pix model, illustrating the process of cross-domain translation.</p>
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<p>The two-phase progressive reasoning process that employs two concatenated Pix2Pix models.</p>
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<p>The suggested design scheme of the trained models and their correlation with surrounding areas: The <b>left column</b> (<b>L1</b>–<b>L3</b>) represents landscape connectivity for wildlife, while the <b>right column</b> (<b>R1</b>–<b>R3</b>) displays maps illustrating landscape materiality. Horizontally, from top to bottom, are the site’s current condition, outputs from the NBI dataset, and outputs from the eBird dataset.</p>
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<p>Measuring the distance between the suggested materiality and the actual materiality of the site.</p>
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<p>The linear regression for overall landscape connectivity Cm and HOG variance V is conducted using NBI (<b>top</b>) and eBird (<b>bottom</b>) data. The HOG sampling is performed on images with a resolution of 256 × 256 pixels.</p>
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<p>A listing of all the LCw’ candidates with corresponding Cm values for NBI (<b>upper row</b>) and eBird (<b>lower row</b>) groups. NBI_LCw’_0.png and eBird_LCw’_3.png are selected due to their proximity to their mappings within the ‘good ecological connected landscape’ model.</p>
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<p>The LCw’ candidates with corresponding V values for NBI (<b>upper row</b>) and eBird (<b>lower row</b>) groups.</p>
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<p>Joint latent space visualisation for NBI and eBird LCw data. Images with turquoise borders are from the NBI dataset, while gold-bordered ones are from the eBird dataset. The two images marked by red borders represent selected LCw’ maps from both datasets. Central cross-shaped icons denote the centroids of the NBI and eBird populations.</p>
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<p>A visualisation of the joint latent space of NBI and eBird landscape materiality data.</p>
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20 pages, 2929 KiB  
Article
Advancing Solar Power Forecasting: Integrating Boosting Cascade Forest and Multi-Class-Grained Scanning for Enhanced Precision
by Mohamed Khalifa Boutahir, Yousef Farhaoui, Mourade Azrour, Ahmed Sedik and Moustafa M. Nasralla
Sustainability 2024, 16(17), 7462; https://doi.org/10.3390/su16177462 - 29 Aug 2024
Viewed by 659
Abstract
Accurate solar power generation forecasting is paramount for optimizing renewable energy systems and ensuring sustainability in our evolving energy landscape. This study introduces a pioneering approach that synergistically integrates Boosting Cascade Forest and multi-class-grained scanning techniques to enhance the precision of solar farm [...] Read more.
Accurate solar power generation forecasting is paramount for optimizing renewable energy systems and ensuring sustainability in our evolving energy landscape. This study introduces a pioneering approach that synergistically integrates Boosting Cascade Forest and multi-class-grained scanning techniques to enhance the precision of solar farm power output predictions significantly. While Boosting Cascade Forest excels in capturing intricate, nonlinear variable interactions through ensemble decision tree learning, multi-class-grained scanning reveals fine-grained patterns within time-series data. Evaluation with real-world solar farm data demonstrates exceptional performance, reflected in low error metrics (mean absolute error, 0.0016; root mean square error 0.0036) and an impressive R-squared score of 99.6% on testing data. This research represents the inaugural application of these advanced techniques to solar generation forecasting, highlighting their potential to revolutionize renewable energy integration, streamline maintenance, and reduce costs. Opportunities for further refinement of ensemble models and exploration of probabilistic forecasting methods are also discussed, underscoring the significance of this work in advancing solar forecasting techniques for a sustainable energy future. Full article
(This article belongs to the Special Issue Solar Energy Utilization and Sustainable Development)
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<p>Solar power generation and distribution process.</p>
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<p>Solar power generation and grid decarbonization pathway.</p>
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<p>Solar irradiation by time: hourly, daily, weekly, and monthly.</p>
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<p>Daily solar energy yield over time.</p>
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<p>AC and DC power output over sample day.</p>
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<p>Illustration of a typical deep-boosting cascade forest.</p>
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<p>Scatter Plot (<b>a</b>) and Scale-location Plot (<b>b</b>) for the Actual vs. Predicted data values.</p>
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<p>QQ plot comparing observed and predicted solar energy generation.</p>
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10 pages, 4214 KiB  
Proceeding Paper
Color Images in Architecture for Stress-Relief
by Yung-Chia Chiu, Ming-Chyuan Ho, Jui-Che Tu and Zhi-Xuan Yang
Eng. Proc. 2024, 74(1), 18; https://doi.org/10.3390/engproc2024074018 - 28 Aug 2024
Viewed by 167
Abstract
The emotional responses and perceptual preferences of individuals for urban public spaces are shaped by their interactions with the physical environment. Emotions and perceptions are inextricably linked, forming the basis of people’s spatial experience. For instance, the presence of dense city buildings can [...] Read more.
The emotional responses and perceptual preferences of individuals for urban public spaces are shaped by their interactions with the physical environment. Emotions and perceptions are inextricably linked, forming the basis of people’s spatial experience. For instance, the presence of dense city buildings can result in feelings of crowding and friction. By improving the urban landscape, it is possible to reduce the stress experienced by citizens. In this study, architectural styles and building facade colors were examined to explore design approaches and features of stress-relieving building facades and identify metrics that measure participants’ stress-relief when viewing buildings. The color of 600 buildings in Japan and Taiwan was analyzed to understand stress-relief from architecture. Semi-structured interviews were conducted with 70 participants who viewed images of 30 buildings. The semantic differential method with a seven-point image scale was employed to assess the stress-relieving potential of different architectural styles and colors. The findings of this study indicated that participants perceived that architectural colors influenced feelings of relief. Additionally, they anticipated variations in architectural colors contingent on architectural usage patterns. To substantiate this observation, three principles—city image, identity, and spiritual atmosphere—were identified as fundamental elements in designing cities for livability. The three principles are illustrated by several case studies for a detailed understanding of their applicability in biodesign practices. Full article
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<p>Spirituality of a city.</p>
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<p>Framework of this research.</p>
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<p>Study procedure.</p>
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<p>Color comparison of public buildings in Japan and Taiwan.</p>
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<p>Color comparison of residential buildings in Japan and Taiwan.</p>
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<p>Color comparison of religious buildings in Japan and Taiwan.</p>
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<p>Public buildings.</p>
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<p>Residential buildings.</p>
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<p>Religious buildings.</p>
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<p>Seven-point scale of building ratings.</p>
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22 pages, 11157 KiB  
Article
Multi-Dimensional Landscape Connectivity Index for Prioritizing Forest Cover Change Scenarios: A Case Study of Southeast China
by Zhu He, Zhihui Lin, Qianle Xu, Shanshan Ding, Xiaochun Bao, Xuefei Li, Xisheng Hu and Jian Li
Forests 2024, 15(9), 1490; https://doi.org/10.3390/f15091490 - 25 Aug 2024
Viewed by 400
Abstract
Predicting forest cover change (FCC) and screening development scenarios are crucial for ecological resilience. However, quantitative evaluations of prioritizing forest change scenarios are limited. Here, we took five shared socio-economic pathways (SSPs) representing potential global changes, namely SSP1: sustainability, SSP2: middle of the [...] Read more.
Predicting forest cover change (FCC) and screening development scenarios are crucial for ecological resilience. However, quantitative evaluations of prioritizing forest change scenarios are limited. Here, we took five shared socio-economic pathways (SSPs) representing potential global changes, namely SSP1: sustainability, SSP2: middle of the road, SSP3: regional rivalry, SSP4: inequality, and SSP5: fossil-fueled development, which were constructed by integrated assessment and climate models. We modeled them with the patch-generating land use simulation (PLUS) and constructed a multi-dimensional landscape connectivity index (MLCI) employing forest landscape connectivity (FLC) indices to assess forest development in Fujian Province, Southeast China. The MLCI visualized by radar charts was based on five metrics, including forest patch size (class area (CA), number (patch density (PD), isolation (landscape division index (DIVISION), aggregation (mean nearest-neighbor index (ENN_MN), and connectance index, (CONNECT). The results indicate that FC will remain above 61.4% until 2030, with growth observed in SSP1 and SSP4. Particularly, FC in SSP4 substantially increased, converted from cropland (1140.809 km2) and grassland (645.741 km2). SSP4 has the largest MLCI values and demonstrates significant enhancements in forest landscape integrity, with CA, ENN_MN and CONNECT increasing greatly. Our study offers valuable approaches to and insights into forest protection and restoration. Full article
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<p>The geographical location and the Köppen-Geiger climate classification of Fujian Province in southeast China. (<b>a</b>) Location and administrative divisions of the Fujian Province in China. (<b>b</b>) Koppen-Geiger climate classification of Fujian Province. (<b>c</b>) Elevation, latitude and longitude of Fujian Province. Note: Cwa: temperate, dry winter, hot summer; Cfa: temperate, no dry season, hot summer; Cfb: temperate, no dry season, warm summer.</p>
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<p>Workflow of the study.</p>
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<p>Composition and structure of the multi-dimensional landscape connectivity indices (MLCIs). Note: <span class="html-italic">a</span>, <span class="html-italic">b</span>, <span class="html-italic">c</span>, <span class="html-italic">d</span>, and <span class="html-italic">e</span> stand for the FLC index values.</p>
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<p>Observed and simulated LUCs in 2020. (<b>a</b>) Observed LUC in 2020. (<b>b</b>) Simulated LUC in 2020. (<b>c</b>) Difference between observed and simulated LUCs in 2020. Note: A1 and A2: cases of observed LUC; B1 and B2: cases of simulated LUC; C1 and C2: cases of difference between observed and simulated LUCs; CL: cropland; F: forest; GL: grassland; WA: water area; BL: built-up land; UL: unused land.</p>
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<p>Spatial distribution and transfer of LUCs from 2000 to 2020.</p>
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<p>Predictions of spatial distribution and transfer of LUCs in multi-scenarios from 2020 to 2030, and dynamic degree of single land use (K) from 2000 to 2030. (<b>a</b>–<b>e</b>) are spatial distribution and transfer of LUCs in SSP1–SSP5, respectively. (<b>f</b>) describes the dynamic degree of single land use. Note: S2020 and S2030 stand for LUCs in 2020 and 2030 in multi−scenarios, respectively. The values of 00–10, 10–20, and 00–20 represent the periods of 2000–2010, 2010–2020, and 2000–2020, respectively.</p>
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<p>Changes in global FLC indices in multi-scenarios from 2000 to 2030. Note: CA: class area; PD: patch density; DIVISION: landscape division index; ENN_MN: mean nearest-neighbor index; CONNECT: connectance index. Non-predicted value: observed FLC indices for Fujian Province from 2000 to 2020.</p>
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<p>Comparison of global MLCIs in multi-scenarios in 2030. Radar chart for the CONNECT 90 m threshold (<b>a</b>), 300 m threshold (<b>b</b>), 600 m threshold (<b>c</b>), and 1200 m threshold (<b>d</b>). The bar chart represents the area of the radar graph for each scenario—MLCI values (<b>e</b>).</p>
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<p>Distribution of local FLC indices for SSP4 in 2030. Note: CA: class area; PD: patch density; DIVISION: landscape division index; ENN_MN: mean nearest-neighbor index; CONNECT: connectance index.</p>
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<p>Changes in local FLC indices in multi-scenarios in 2030. Note: CA: class area; PD: patch density; DIVISION: landscape division index; ENN_MN: mean nearest-neighbor index; CONNECT: connectance index.</p>
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<p>Comparison of local MLCIs in multi-scenarios in 2030. Radar charts for CONNECT 90 m threshold (<b>a</b>), 300 m threshold (<b>b</b>), 600 m threshold (<b>c</b>), and 1200 m threshold (<b>d</b>). Radar chart area in multi-scenarios (<b>e</b>). The bar chart represents the area of the radar graph under each scenario—MLCI values (<b>e</b>).</p>
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<p>The distribution of PD index changes under SSP4 from 2020 to 2030. PD: patch density.</p>
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30 pages, 8447 KiB  
Review
Aircraft Electrification: Insights from a Cross-Sectional Thematic and Bibliometric Analysis
by Raj Bridgelall
World Electr. Veh. J. 2024, 15(9), 384; https://doi.org/10.3390/wevj15090384 - 24 Aug 2024
Viewed by 437
Abstract
Electrifying aircraft, a crucial advancement in the aviation industry, aims to cut pollutive emissions and boost energy efficiency. Traditional aircraft depend on fossil fuels, which contribute significantly to greenhouse gas emissions and environmental pollution. Despite progress in electric propulsion and energy storage technologies, [...] Read more.
Electrifying aircraft, a crucial advancement in the aviation industry, aims to cut pollutive emissions and boost energy efficiency. Traditional aircraft depend on fossil fuels, which contribute significantly to greenhouse gas emissions and environmental pollution. Despite progress in electric propulsion and energy storage technologies, challenges such as low energy density and integration issues persist. This paper provides a comprehensive thematic and bibliometric analysis to map the research landscape in aircraft electrification, identifying key research themes, influential contributors, and emerging trends. This study applies natural language processing to unstructured bibliographic data and cross-sectional statistical methods to analyze publications, citations, and keyword distributions across various categories related to aircraft electrification. The findings reveal significant growth in research output, particularly in energy management and multidisciplinary design analysis. Collaborative networks highlight key international partnerships, with the United States and China being key research hubs, while citation metrics highlight the impact of leading researchers and institutions in these countries. This study provides valuable insights for researchers, policymakers, and industry stakeholders, guiding future research directions and collaborations. Full article
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<p>The analytical workflow developed in this study.</p>
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<p>Bigram word cloud within categories.</p>
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<p>Bigram word frequency within categories.</p>
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<p>Author keyword cloud within categories.</p>
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<p>Top five author keywords within categories.</p>
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<p>(<b>a</b>) Term co-occurrence and clusters, and (<b>b</b>) highlighted example of “composite material”.</p>
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<p>Number of terms as a function of their minimum number of occurrences in the corpus.</p>
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<p>Publications by (<b>a</b>) year, (<b>b</b>) category, (<b>c</b>) author count distribution, and (<b>d</b>) category.</p>
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<p>Publications by top 10 (<b>a</b>) lead authors, (<b>b</b>) countries, (<b>c</b>) affiliations, and (<b>d</b>) journals.</p>
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<p>Citations (<b>a</b>) of top 10 lead authors, (<b>b</b>) of the lead author in top 10 countries, (<b>c</b>) of the lead author in top 10 affiliations, and (<b>d</b>) in category by year.</p>
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<p>Authorship collaborations across countries.</p>
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<p>Citations (<b>a</b>) by year, (<b>b</b>) per publication by year, (<b>c</b>) per publication by country, and (<b>d</b>) per publication by affiliation.</p>
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<p>(<b>a</b>) Citations in category, (<b>b</b>) citations per publication in category, (<b>c</b>) citations per publication in category, and (<b>d</b>) publications in category by top 10 countries.</p>
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39 pages, 2593 KiB  
Review
From Near-Sensor to In-Sensor: A State-of-the-Art Review of Embedded AI Vision Systems
by William Fabre, Karim Haroun, Vincent Lorrain, Maria Lepecq and Gilles Sicard
Sensors 2024, 24(16), 5446; https://doi.org/10.3390/s24165446 - 22 Aug 2024
Viewed by 710
Abstract
In modern cyber-physical systems, the integration of AI into vision pipelines is now a standard practice for applications ranging from autonomous vehicles to mobile devices. Traditional AI integration often relies on cloud-based processing, which faces challenges such as data access bottlenecks, increased latency, [...] Read more.
In modern cyber-physical systems, the integration of AI into vision pipelines is now a standard practice for applications ranging from autonomous vehicles to mobile devices. Traditional AI integration often relies on cloud-based processing, which faces challenges such as data access bottlenecks, increased latency, and high power consumption. This article reviews embedded AI vision systems, examining the diverse landscape of near-sensor and in-sensor processing architectures that incorporate convolutional neural networks. We begin with a comprehensive analysis of the critical characteristics and metrics that define the performance of AI-integrated vision systems. These include sensor resolution, frame rate, data bandwidth, computational throughput, latency, power efficiency, and overall system scalability. Understanding these metrics provides a foundation for evaluating how different embedded processing architectures impact the entire vision pipeline, from image capture to AI inference. Our analysis delves into near-sensor systems that leverage dedicated hardware accelerators and commercially available components to efficiently process data close to their source, minimizing data transfer overhead and latency. These systems offer a balance between flexibility and performance, allowing for real-time processing in constrained environments. In addition, we explore in-sensor processing solutions that integrate computational capabilities directly into the sensor. This approach addresses the rigorous demand constraints of embedded applications by significantly reducing data movement and power consumption while also enabling in-sensor feature extraction, pre-processing, and CNN inference. By comparing these approaches, we identify trade-offs related to flexibility, power consumption, and computational performance. Ultimately, this article provides insights into the evolving landscape of embedded AI vision systems and suggests new research directions for the development of next-generation machine vision systems. Full article
(This article belongs to the Special Issue Sensor Technology for Intelligent Control and Computer Visions)
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<p>Functional view of an integrated vision system with AI processing such as [<a href="#B23-sensors-24-05446" class="html-bibr">23</a>,<a href="#B24-sensors-24-05446" class="html-bibr">24</a>,<a href="#B25-sensors-24-05446" class="html-bibr">25</a>].</p>
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<p>Design space for AI vision systems, highlighting the trade-off between flexibility and power consumption across processing configurations [<a href="#B23-sensors-24-05446" class="html-bibr">23</a>,<a href="#B29-sensors-24-05446" class="html-bibr">29</a>,<a href="#B31-sensors-24-05446" class="html-bibr">31</a>,<a href="#B32-sensors-24-05446" class="html-bibr">32</a>,<a href="#B33-sensors-24-05446" class="html-bibr">33</a>,<a href="#B34-sensors-24-05446" class="html-bibr">34</a>,<a href="#B35-sensors-24-05446" class="html-bibr">35</a>,<a href="#B36-sensors-24-05446" class="html-bibr">36</a>,<a href="#B37-sensors-24-05446" class="html-bibr">37</a>,<a href="#B38-sensors-24-05446" class="html-bibr">38</a>,<a href="#B39-sensors-24-05446" class="html-bibr">39</a>,<a href="#B40-sensors-24-05446" class="html-bibr">40</a>,<a href="#B41-sensors-24-05446" class="html-bibr">41</a>,<a href="#B42-sensors-24-05446" class="html-bibr">42</a>,<a href="#B43-sensors-24-05446" class="html-bibr">43</a>,<a href="#B44-sensors-24-05446" class="html-bibr">44</a>,<a href="#B45-sensors-24-05446" class="html-bibr">45</a>,<a href="#B46-sensors-24-05446" class="html-bibr">46</a>,<a href="#B47-sensors-24-05446" class="html-bibr">47</a>,<a href="#B48-sensors-24-05446" class="html-bibr">48</a>,<a href="#B49-sensors-24-05446" class="html-bibr">49</a>,<a href="#B50-sensors-24-05446" class="html-bibr">50</a>,<a href="#B51-sensors-24-05446" class="html-bibr">51</a>].</p>
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<p>A basic CNN architecture. (<b>a</b>) Shows the network’s structure from input to output, visualizing data processing for predictions. (<b>b</b>) Details the mathematical operations, including weights, biases, and activation functions, that map inputs into outputs.</p>
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<p>Representation of CNN models for embedded systems, showcasing memory requirements, computational demands, and accuracy [<a href="#B14-sensors-24-05446" class="html-bibr">14</a>,<a href="#B58-sensors-24-05446" class="html-bibr">58</a>,<a href="#B59-sensors-24-05446" class="html-bibr">59</a>,<a href="#B76-sensors-24-05446" class="html-bibr">76</a>,<a href="#B80-sensors-24-05446" class="html-bibr">80</a>,<a href="#B81-sensors-24-05446" class="html-bibr">81</a>,<a href="#B82-sensors-24-05446" class="html-bibr">82</a>,<a href="#B83-sensors-24-05446" class="html-bibr">83</a>,<a href="#B84-sensors-24-05446" class="html-bibr">84</a>,<a href="#B85-sensors-24-05446" class="html-bibr">85</a>,<a href="#B86-sensors-24-05446" class="html-bibr">86</a>] for classification tasks on ImageNet-1K [<a href="#B9-sensors-24-05446" class="html-bibr">9</a>]. Each bubble represents a model, with size indicating memory requirements and position reflecting ImageNet’s computational requirements and model accuracy (inspired by ([<a href="#B75-sensors-24-05446" class="html-bibr">75</a>]). Distinctive color patterns in <a href="#sensors-24-05446-f004" class="html-fig">Figure 4</a> categorize the models by their accuracy and implementation complexity, illustrating the trade-offs between accuracy, number of parameters, MAC requirements, and ease of layer implementation.</p>
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<p>Representation of uniform and non-uniform quantization (inspired by [<a href="#B111-sensors-24-05446" class="html-bibr">111</a>]). The process converts full-precision weights and activations to lower bit-width representations, reducing the model size and computational requirements while preserving accuracy.</p>
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<p>Representation of structured and unstructured pruning. Unstructured pruning removes individual weights across filters, allowing for fine-grained sparsity but potentially irregular computation patterns. Structured pruning removes entire channels or filters, resulting in a more regular pruned architecture that can be more efficiently implemented in hardware.</p>
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<p>Simplified architectural view of near-sensor AI vision systems.</p>
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<p>Simplified architectural view of in-sensor AI vision systems.</p>
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