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Keywords = double total domination number

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42 pages, 9592 KiB  
Article
Air Route Network Planning Method of Urban Low-Altitude Logistics UAV with Double-Layer Structure
by Zhuolun Li, Shan Li, Jian Lu and Sixi Wang
Drones 2025, 9(3), 193; https://doi.org/10.3390/drones9030193 - 6 Mar 2025
Cited by 1 | Viewed by 1747
Abstract
With the rapid development of e-commerce, logistics UAVs (unmanned aerial vehicles) have shown great potential in the field of urban logistics. However, the large-scale operation of logistics UAVs has brought challenges to air traffic management, and the competitiveness of UAV logistics is still [...] Read more.
With the rapid development of e-commerce, logistics UAVs (unmanned aerial vehicles) have shown great potential in the field of urban logistics. However, the large-scale operation of logistics UAVs has brought challenges to air traffic management, and the competitiveness of UAV logistics is still weak compared with traditional ground logistics. Therefore, this paper constructs a double-layer route network structure that separates logistics transshipment from terminal delivery. In the delivery layer, a door-to-door distribution mode is adopted, and the transshipment node service location model is constructed, so as to obtain the location of the transshipment node and the service relationship. In the transshipment layer, the index of the route betweenness standard deviation (BSD) is introduced to construct the route network planning model. In order to solve the above model, a double-layer algorithm was designed. In the upper layer, the multi-objective simulated annealing algorithm (MOSA) is used to solve the transshipment node service location issue, and in the lower layer, the multi-objective non-dominated sorting genetic algorithm II (NSGA-II) is adopted to solve the network planning model. Based on real obstacle data and the demand situation, the double-layer network was constructed through simulation experiments. To verify the network rationality, actual flights were carried out on some routes, and it was found that the gap between the UAV’s autonomous flight route time and the theoretical calculations was relatively small. The simulation results show that compared with the single-layer network, the total distance with the double-layer network was reduced by 62.5% and the structural intersection was reduced by 96.9%. Compared with the minimum spanning tree (MST) algorithm, the total task flight distance obtained with the NSGA-II was reduced by 42.4%. The BSD factors can mitigate potential congestion risks. The route network proposed in this paper can effectively reduce the number of intersections and make the UAV passing volume more balanced. Full article
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10 pages, 663 KiB  
Article
Total and Double Total Domination on Octagonal Grid
by Antoaneta Klobučar and Ana Klobučar Barišić
Axioms 2024, 13(11), 792; https://doi.org/10.3390/axioms13110792 - 16 Nov 2024
Cited by 1 | Viewed by 1304
Abstract
A k-total dominating set is a set of vertices such that all vertices in the graph, including the vertices in the dominating set themselves, have at least k neighbors in the dominating set. The k-total domination number [...] Read more.
A k-total dominating set is a set of vertices such that all vertices in the graph, including the vertices in the dominating set themselves, have at least k neighbors in the dominating set. The k-total domination number γkt(G) is the cardinality of the smallest k-total dominating set. For k=1,2, the k-total dominating number is called the total and the double total dominating number, respectively. In this paper, we determine the exact values for the total domination number on a linear and on a double octagonal chain and an upper bound for the total domination number on a triple octagonal chain. Furthermore, we determine the exact values for the double total domination number on a linear and on a double octagonal chain and an upper bound for the double total domination number on a triple octagonal chain and on an octagonal grid Om,n,m3,n3. As each vertex in the octagonal system is either of degree two or of degree three, there is no k-total domination for k3. Full article
(This article belongs to the Special Issue Recent Developments in Graph Theory)
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15 pages, 1606 KiB  
Article
Health Care Utilization for Common Shoulder Disorders: Analysis of the 2010–2019 National Patient Sample Data from the Health Insurance Review and Assessment Service in Korea
by Jin-Young Kang, Doori Kim, Huijun Kim, In-Hyuk Ha and Yoon Jae Lee
Medicina 2024, 60(5), 744; https://doi.org/10.3390/medicina60050744 - 29 Apr 2024
Cited by 4 | Viewed by 1732
Abstract
Background and Objective: The aim of this study was to analyze trends in surgical and non-surgical service utilization for common shoulder disorders in Korea from 2010 to 2019. Methods and Materials: This retrospective, cross-sectional, descriptive study utilized National Patient Sample data from the [...] Read more.
Background and Objective: The aim of this study was to analyze trends in surgical and non-surgical service utilization for common shoulder disorders in Korea from 2010 to 2019. Methods and Materials: This retrospective, cross-sectional, descriptive study utilized National Patient Sample data from the Health Insurance and Review Assessment Service (HIRA) of Korea. These data constitute a 2% sample out of the entire Korean population and include data for a variety of parameters instrumental for health care research. Patients with at least one medical service use for rotator cuff syndrome or tear, impingement syndrome, or adhesive capsulitis between January 2010 and December 2019 were included. Trends in healthcare utilization by disorder type, patient demographics, seasonal service use, and treatment details were examined. Results: There was an upward trend in the total number of patients and costs for shoulder disorders, from 35,798 patients and USD 5,485,196 in 2010 to 42,558 and USD 11,522,543 in 2019, respectively. The number of patients aged ≥60 and hospital visits increased. March had the highest number of claims. Physical therapy was the most common non-surgical procedure, while nerve block claims more than doubled. Opioid prescription rates also tripled. Surgical treatments were dominated by shoulder rotator cuff repair and acromioplasty. Conclusions: There was a significant increase in healthcare utilization for shoulder disorders, marked by rising costs and patient numbers. The use of nerve blocks and opioids notably increased. These data are valuable for clinicians, researchers, and policymakers. Full article
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18 pages, 6748 KiB  
Article
Study on the Influence of Adjacent Double Deep Foundation Pit Excavation Sequence on Existing Tunnel Deformation Based on HSS Constitutive Model
by Sijun Wang, Wenting Wang, Huan Yang, Debin Zhao and Yang Liu
Appl. Sci. 2024, 14(9), 3626; https://doi.org/10.3390/app14093626 - 25 Apr 2024
Cited by 3 | Viewed by 1202
Abstract
With the increase in the number of buildings along the subway, the impact of building construction on the adjacent subway tunnels has gradually come to the forefront and become an important problem to be solved in the engineering field. In particular, the excavation [...] Read more.
With the increase in the number of buildings along the subway, the impact of building construction on the adjacent subway tunnels has gradually come to the forefront and become an important problem to be solved in the engineering field. In particular, the excavation and unloading process of deep foundation pits will trigger an additional deformation of the subway structure, which may pose a serious threat to the safety and stability of subway tunnels. This article is based on a foundation pit project in the sub-center of Beijing, focusing on the form of a connected double foundation pit. Using the HSS constitutive model for soil materials, this study simulates the deformation response of adjacent existing subway tunnels under three excavation sequences: sequential excavation, simultaneous excavation, and the comprehensive excavation of the connected double foundation pits. The study shows that, from the point of view of the total displacement of the whole construction process, the impact of a synchronized excavation of double pits on the existing tunnel line is relatively large in the process, and the impact of sequential excavation is relatively small in the construction cycle. The result of the similarity of the excavation sequence is the similarity of the impact trend. The volume of excavated earth determines the value of displacement change for each excavation scenario in each working condition and is also responsible for the convergence of changes. The trend of total tunnel displacement is more consistent with that of vertical displacement, which is dominated by vertical displacement, with horizontal displacement having a relatively small influence. The maximum value of the total tunnel displacement occurs at the side of the tunnel near the excavation area, and the direction is inclined to the excavation area. The application of supporting structures, especially the center plate and the bottom plate, can suppress the vertical deformation of the tunnel bulge. Full article
(This article belongs to the Special Issue Structural Health Monitoring of Tunnel and Underground Engineering)
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10 pages, 229 KiB  
Article
New Bounds for Three Outer-Independent Domination-Related Parameters in Cactus Graphs
by Abel Cabrera-Martínez, Juan Manuel Rueda-Vázquez and Jaime Segarra
Axioms 2024, 13(3), 177; https://doi.org/10.3390/axioms13030177 - 7 Mar 2024
Viewed by 1166
Abstract
Let G be a nontrivial connected graph. For a set DV(G), we define D¯=V(G)D. The set D is a total outer-independent dominating set of G if [...] Read more.
Let G be a nontrivial connected graph. For a set DV(G), we define D¯=V(G)D. The set D is a total outer-independent dominating set of G if |N(v)D|1 for every vertex vV(G) and D¯ is an independent set of G. Moreover, D is a double outer-independent dominating set of G if |N[v]D|2 for every vertex vV(G) and D¯ is an independent set of G. In addition, D is a 2-outer-independent dominating set of G if |N(v)D|2 for every vertex vD¯ and D¯ is an independent set of G. The total, double or 2-outer-independent domination number of G, denoted by γtoi(G), γ×2oi(G) or γ2oi(G), is the minimum cardinality among all total, double or 2-outer-independent dominating sets of G, respectively. In this paper, we first show that for any cactus graph G of order n(G)4 with k(G) cycles, γ2oi(G)n(G)+l(G)2+k(G), γtoi(G)2n(G)l(G)+s(G)3+k(G) and γ×2oi(G)2n(G)+l(G)+s(G)3+k(G), where l(G) and s(G) represent the number of leaves and the number of support vertices of G, respectively. These previous bounds extend three known results given for trees. In addition, we characterize the trees T with γ×2oi(T)=γtoi(T). Moreover, we show that γ2oi(T)n(T)+l(T)s(T)+12 for any tree T with n(T)3. Finally, we give a constructive characterization of the trees T that satisfy the equality above. Full article
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14 pages, 7647 KiB  
Article
Effects of Diesel Emissions on Black Carbon and Particle Number Concentrations in the Eastern U.S.
by Laura N. Posner and Spyros N. Pandis
Atmosphere 2024, 15(2), 199; https://doi.org/10.3390/atmos15020199 - 5 Feb 2024
Viewed by 1558
Abstract
The effects of emissions of diesel engines on black carbon and particle number concentrations, as well as climate-relevant aerosol properties, are explored for a summertime period in the Eastern U.S. using the chemical transport model PMCAMx-UF. A 50% reduction in diesel particulate emissions [...] Read more.
The effects of emissions of diesel engines on black carbon and particle number concentrations, as well as climate-relevant aerosol properties, are explored for a summertime period in the Eastern U.S. using the chemical transport model PMCAMx-UF. A 50% reduction in diesel particulate emissions results in lower (23%) black carbon mass concentrations, as expected, and similar changes both in magnitude (27–30%) and spatial pattern for the absorption coefficient. However, an average 2% increase in the total particle number concentrations is predicted due to a decrease in the coagulation and condensation sinks and, at the same time, a 2% decrease in N100 (particles larger than 100 nm) concentrations. The diesel reduction results suggest that mitigation of large diesel particles and/or particle mass emissions can reduce climate-relevant properties related to the absorption of black carbon and provide health benefits; however, the changes could also have the unintended effect of increased ultrafine particle number concentrations. Changes in cloud condensation nuclei are predicted to be significantly less than expected, assuming a proportional reduction during this photochemically active period. Doubling the diesel emissions results in a domain-averaged 3% decrease in total particle number concentrations and a 3% increase in N100 concentrations. PM2.5 BC concentrations increase on average by 46%, and similar changes (52–60%) are predicted for the absorption coefficient. Extinction coefficients for both perturbation simulations changed by only a few percent due to the dominance of scattering aerosols in the Eastern U.S. during this period characterized by high photochemical activity. Full article
(This article belongs to the Special Issue Urban Air Quality Modelling)
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18 pages, 4672 KiB  
Article
Mammal Roadkills in Lithuanian Urban Areas: A 15-Year Study
by Linas Balčiauskas, Andrius Kučas and Laima Balčiauskienė
Animals 2023, 13(20), 3272; https://doi.org/10.3390/ani13203272 - 19 Oct 2023
Cited by 8 | Viewed by 1896
Abstract
We investigated roadkills in urban areas in Lithuania from 2007 to 2022, including two periods with COVID-19 restrictions on people’s movement. We analyzed the proportions of wild and domestic animals in roadkill, annual trends, the predominant species involved, and monthly changes during the [...] Read more.
We investigated roadkills in urban areas in Lithuania from 2007 to 2022, including two periods with COVID-19 restrictions on people’s movement. We analyzed the proportions of wild and domestic animals in roadkill, annual trends, the predominant species involved, and monthly changes during the restrictions. Urban roads were characterized by a low species diversity of roadkilled mammals, with roe deer (Capreolus capreolus) dominating. Total numbers increased exponentially during the study period. The proportion of domestic animals, 12.2%, significantly exceeded that on non-urban roads in the country. The proportion of domestic animals decreased from over 40% in 2007–2009 to 3.7–5.4% in 2020–2022, while the proportion of wild mammals increased from 36.1–39.6% to 89.9–90.6%, respectively. During the periods of COVID-19 restrictions, the number of roadkills in urban areas was significantly higher than expected based on long-term trends. Compared to 2019, the number of roadkilled roe deer in 2020–2021 almost doubled from 700 to 1281–1325 individuals. These anthropause effects were, however, temporary. The imbalance between the roadkill number and transport intensity might require new mitigation strategies to sustain mammal populations in urban areas, at least through improving driver awareness on the issue. Full article
(This article belongs to the Section Mammals)
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14 pages, 3183 KiB  
Article
Analyzing the Land Use and Cover Change Inside and Outside China’s Ecological Function Area
by Yajuan Wang, Yongheng Rao and Hongbo Zhu
Land 2023, 12(7), 1447; https://doi.org/10.3390/land12071447 - 20 Jul 2023
Cited by 4 | Viewed by 2502
Abstract
The establishment of nature reserves and ecological function areas is crucial for preserving the natural environment and the invaluable services provided by ecosystems. In our study, we conducted a comprehensive analysis using the 2011–2020 Chinese land cover dataset to examine the impact of [...] Read more.
The establishment of nature reserves and ecological function areas is crucial for preserving the natural environment and the invaluable services provided by ecosystems. In our study, we conducted a comprehensive analysis using the 2011–2020 Chinese land cover dataset to examine the impact of ecological function areas on regional land use and cover change. This analysis allowed us to quantify and visualize the intensity, aggregation effects, and transformation paths of land cover change while considering China’s ecological function areas. Our findings highlight notable disparities in land cover types between the ecological function area and its surroundings. Within the ecological function area, forest and grassland dominate, constituting 67% of the total land cover. In contrast, outside the ecological function area, there is a greater presence of wasteland, in addition to forest and grassland. Moreover, the abundance of impervious surfaces, which are closely linked to human activities, is significantly higher outside the ecological function area, almost double the amount found inside. By examining specific land cover types, we observed that forests exhibit the least change within the ecological function area, whereas croplands experience the least change outside. Throughout the study period, approximately 8.1% of land cover pixels underwent changes, with some areas displaying a frequency of change reaching up to 2. Interestingly, the number of high-frequency land use and cover change pixels inside the ecological function area is only half of the outside. Notably, a higher percentage of impervious surfaces within the ecological function area (0.13%) were converted into cropland compared to the outside (0.07%). Understanding the dynamics of land cover change within China’s ecological function areas provides valuable insights for effective land resource management and planning. It enables us to make informed decisions to ensure the sustainable development and conservation of these areas. Full article
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25 pages, 4804 KiB  
Article
The Changes in Dominant Driving Factors in the Evolution Process of Wetland in the Yellow River Delta during 2015–2022
by Cuixia Wei, Bing Guo, Miao Lu, Wenqian Zang, Fei Yang, Chuan Liu, Baoyu Wang, Xiangzhi Huang, Yifeng Liu, Yang Yu, Jialin Li and Mei Xu
Remote Sens. 2023, 15(11), 2858; https://doi.org/10.3390/rs15112858 - 31 May 2023
Cited by 5 | Viewed by 2284
Abstract
Most of the previous studies exploring the changing patterns of wetland in the Yellow River Delta (YRD) were conducted based on sparse time-series images, which ignored its severe environmental gradient and rapid evolution process of the wetland. The changes in the dominant factors [...] Read more.
Most of the previous studies exploring the changing patterns of wetland in the Yellow River Delta (YRD) were conducted based on sparse time-series images, which ignored its severe environmental gradient and rapid evolution process of the wetland. The changes in the dominant factors in the evolution of the wetland in the YRD are not clear. This study used the dense time-series Sentinel-2 images to establish a wetland database of the YRD, and then analyzed the spatial distribution characteristics of, and temporal changes in, the wetland during 2015–2022. Finally, the dominant factors of the spatio-temporal evolutions of the wetland were explored and revealed. The results showed the following. (1) During 2015–2022, the wetland in the YRD was dominated by artificial wetland, accounting for 54.02% of the total wetland area in the study area. In 2015–2022, the total wetland area increased by 309.90 km2, including an increase of 222.63 km2 in natural wetlands and 87.27 km2 in artificial wetlands. In the conversion between wetland types, 218.73 km2 of artificial wetlands were converted into natural wetlands, and 75.18 km2 of natural wetlands were converted into artificial wetlands. The patch density of rivers, swamps, and salt pans increased, showing a trend of fragmentation. However, the overall degree of landscape fragmentation in wetlands weakened. The trend of changes in the number of patches and landscape shape index was the same, while the trend of changes in Shannon’s diversity index and Contagion index was completely opposite. (2) Natural factors, such as precipitation (0.51, 2015; 0.65, 2016), DEM (0.57, 2017; 0.47, 2018; 0.49, 2020; 0.46, 2021), vegetation coverage (0.59, 2019), and temperature (0.48, 2022), were the dominant influencing factors of wetland changes in the YRD. The dominant single factor causing the changes in artificial wetlands was vegetation coverage, while socio-economic factors had lower explanatory power, with the average q value of 0.18. (3) During 2015–2022, the interactions between the natural and artificial factors of the wetland changes were mostly nonlinear and showed double-factor enhancement. The interactions between temperature and sunshine hours had the largest explanatory power for natural wetland change, while interactions between precipitation and vegetation coverage, and between temperature and vegetation coverage, had large contribution rates for artificial wetland change. The interactions among natural factors had the greatest impacts on wetland change, followed by interactions between natural factors and socio-economic factors, while interactions among socio-economic factors had more slight impacts on wetland change. The results can provide a scientific basis for regional wetland protection and management. Full article
(This article belongs to the Special Issue Recent Progress of Change Detection Based on Remote Sensing)
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20 pages, 1983 KiB  
Article
Approaches and Reforms in Undergraduate Education for Integration of Major and General Education: A Comparative Study among Teaching, Teaching—Research, and Research Universities in China
by Changfeng Xue, Tianping Yang and Muhammad Umair
Sustainability 2023, 15(2), 1251; https://doi.org/10.3390/su15021251 - 9 Jan 2023
Cited by 3 | Viewed by 2709
Abstract
With the major education model as the dominant model, general education is squeezed in quality and quantity, and implementing the concept of general education is challenging. There are several problems in undergraduate education with “strong majors and weak general education” that need to [...] Read more.
With the major education model as the dominant model, general education is squeezed in quality and quantity, and implementing the concept of general education is challenging. There are several problems in undergraduate education with “strong majors and weak general education” that need to be addressed in order to integrate major education with general education. Therefore, we selected three levels of universities: nine first-class research universities, seven key provincial teaching–research universities, and seven teaching universities from China. One-way ANOVA, principal component analysis (PCA), and cluster analysis were used to analyze the differences in three kinds of universities based on the total undergrad credits and “big category” majors. One-way ANOVA results showed that “total undergrad credits” and “big category” majors are significantly different between research universities, teaching–research universities, and teaching universities, but there are no significant differences in minor course credits, general course credits, disciplinary and major basic course credits, and elective course credits. Based on cluster analysis, the first cluster G1 showed that all the research universities had similarities in the total undergrad credits, minor course credits, general course credits, disciplinary and major basic course credits, elective course credits, and “big category” majors. PCA results confirmed that research universities are significantly separated from teaching universities and teaching–research universities at the PC1 axis, which has a higher number of “big category” majors. There are three key issues with strong majors and weak general education: (1) the difficulties in popularizing the progressive minor training model; (2) the low percentage of elective courses, general elective courses, and individualized courses; and (3) major transfer system restrictions. Based on their own student characteristics and school resources, teaching universities, research universities, and teaching–research universities are encouraged to enhance the cultivation of students’ compound knowledge and skills at the three levels of micro-major, double degree (minor degree), and minor-major (double majors or second majors), respectively. The universities should adhere to the diversified combination of general and major education, the integration-oriented undergraduate education, the reform concept of reducing burden and improving quality, appropriately increase students’ freedom of choice in undergraduate instructional management for an effective combination of “general education and major education”, and then bring the undergraduate education to a characteristic and high level. Full article
(This article belongs to the Special Issue Approach and Policy in Higher Education for Sustainability)
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16 pages, 2545 KiB  
Article
Increased Gene Targeting in Hyper-Recombinogenic LymphoBlastoid Cell Lines Leaves Unchanged DSB Processing by Homologous Recombination
by Emil Mladenov, Katja Paul-Konietzko, Veronika Mladenova, Martin Stuschke and George Iliakis
Int. J. Mol. Sci. 2022, 23(16), 9180; https://doi.org/10.3390/ijms23169180 - 16 Aug 2022
Cited by 4 | Viewed by 2758
Abstract
In the cells of higher eukaryotes, sophisticated mechanisms have evolved to repair DNA double-strand breaks (DSBs). Classical nonhomologous end joining (c-NHEJ), homologous recombination (HR), alternative end joining (alt-EJ) and single-strand annealing (SSA) exploit distinct principles to repair DSBs throughout the cell cycle, resulting [...] Read more.
In the cells of higher eukaryotes, sophisticated mechanisms have evolved to repair DNA double-strand breaks (DSBs). Classical nonhomologous end joining (c-NHEJ), homologous recombination (HR), alternative end joining (alt-EJ) and single-strand annealing (SSA) exploit distinct principles to repair DSBs throughout the cell cycle, resulting in repair outcomes of different fidelity. In addition to their functions in DSB repair, the same repair pathways determine how cells integrate foreign DNA or rearrange their genetic information. As a consequence, random integration of DNA fragments is dominant in somatic cells of higher eukaryotes and suppresses integration events at homologous genomic locations, leading to very low gene-targeting efficiencies. However, this response is not universal, and embryonic stem cells display increased targeting efficiency. Additionally, lymphoblastic chicken and human cell lines DT40 and NALM6 show up to a 1000-fold increased gene-targeting efficiency that is successfully harnessed to generate knockouts for a large number of genes. We inquired whether the increased gene-targeting efficiency of DT40 and NALM6 cells is linked to increased rates of HR-mediated DSB repair after exposure to ionizing radiation (IR). We analyzed IR-induced γ-H2AX foci as a marker for the total number of DSBs induced in a cell and RAD51 foci as a marker for the fraction of those DSBs undergoing repair by HR. We also evaluated RPA accretion on chromatin as evidence for ongoing DNA end resection, an important initial step for all pathways of DSB repair except c-NHEJ. We finally employed the DR-GFP reporter assay to evaluate DSB repair by HR in DT40 cells. Collectively, the results obtained, unexpectedly show that DT40 and NALM6 cells utilized HR for DSB repair at levels very similar to those of other somatic cells. These observations uncouple gene-targeting efficiency from HR contribution to DSB repair and suggest the function of additional mechanisms increasing gene-targeting efficiency. Indeed, our results show that analysis of the contribution of HR to DSB repair may not be used as a proxy for gene-targeting efficiency. Full article
(This article belongs to the Special Issue Advances and Challenges in Biomolecular Radiation Research 2.0)
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24 pages, 18073 KiB  
Article
Spatiotemporal Evolution Pattern and Driving Mechanisms of Landslides in the Wenchuan Earthquake-Affected Region: A Case Study in the Bailong River Basin, China
by Linxin Lin, Guan Chen, Wei Shi, Jiacheng Jin, Jie Wu, Fengchun Huang, Yan Chong, Yang Meng, Yajun Li and Yi Zhang
Remote Sens. 2022, 14(10), 2339; https://doi.org/10.3390/rs14102339 - 12 May 2022
Cited by 10 | Viewed by 3539
Abstract
Understanding the spatiotemporal evolution and driving mechanisms of landslides following a mega-earthquake at the catchment scale can lead to improved landslide hazard assessment and reduced related risk. However, little effort has been made to undertake such research in the Wenchuan earthquake-affected region, outside [...] Read more.
Understanding the spatiotemporal evolution and driving mechanisms of landslides following a mega-earthquake at the catchment scale can lead to improved landslide hazard assessment and reduced related risk. However, little effort has been made to undertake such research in the Wenchuan earthquake-affected region, outside Sichuan Province, China. In this study, we used the Goulinping valley in the Bailong River basin in southern Gansu Province, China, as an example. By examining the multitemporal inventory, we revealed various characteristics of the spatiotemporal evolution of landslides over the past 13 years (2007–2020). We evaluated the activity of landslides using multisource remote-sensing technology, analyzed the driving mechanisms of landslides, and further quantified the contribution of landslide evolution to debris flow in the catchment. Our results indicate that the number of landslides increased by nearly six times from 2007 to 2020, and the total volume of landslides approximately doubled. The evolution of landslides in the catchment can be divided into three stages: the earthquake driving stage (2008), the coupled driving stage of earthquake and rainfall (2008–2017), and the rainfall driving stage (2017–present). Landslides in the upstream limestone area were responsive to earthquakes, while the middle–lower loess–phyllite-dominated reaches were mainly controlled by rainfall. Thus, the current landslides in the upstream region remain stable, and those in the mid-downstream are vigorous. Small landslides and mid-downstream slope erosion can rapidly provide abundant debris flow and reduce its threshold, leading to an increase in the frequency and scale of debris flow. This study lays the foundation for studying landslide mechanisms in the Bailong River basin or similar regions. It also aids in engineering management and landslide risk mitigation under seismic activity and climate change conditions. Full article
(This article belongs to the Special Issue Remote Sensing Analysis of Geologic Hazards)
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20 pages, 1776 KiB  
Article
Optimal Allocation of a Hybrid Photovoltaic Biogas Energy System Using Multi-Objective Feasibility Enhanced Particle Swarm Algorithm
by Hussein M. K. Al-Masri, Abed A. Al-Sharqi, Sharaf K. Magableh, Ali Q. Al-Shetwi, Maher G. M. Abdolrasol and Taha Selim Ustun
Sustainability 2022, 14(2), 685; https://doi.org/10.3390/su14020685 - 9 Jan 2022
Cited by 15 | Viewed by 3035
Abstract
This paper aims to investigate a hybrid photovoltaic (PV) biogas on-grid energy system in Al-Ghabawi territory, Amman, Jordan. The system is accomplished by assessing the system’s reliability and economic viability. Realistic hourly measurements of solar irradiance, ambient temperature, municipal solid waste, and load [...] Read more.
This paper aims to investigate a hybrid photovoltaic (PV) biogas on-grid energy system in Al-Ghabawi territory, Amman, Jordan. The system is accomplished by assessing the system’s reliability and economic viability. Realistic hourly measurements of solar irradiance, ambient temperature, municipal solid waste, and load demand in 2020 were obtained from Jordanian governmental entities. This helps in investigating the proposed system on a real megawatt-scale retrofitting power system. Three case scenarios were performed: loss of power supply probability (LPSP) with total net present cost (TNPC), LPSP with an annualized cost of the system (ACS), and TNPC with the index of reliability (IR). Pareto frontiers were obtained using multi-objective feasibility enhanced particle swarm optimization (MOFEPSO) algorithm. The system’s decision variables were the number of PV panels (Npv) and the number of biogas plant working hours per day (tbiogas). Moreover, three non-dominant Pareto frontier solutions are discussed, including reliable, affordable, and best solutions obtained by fuzzy logic. Double-diode (DD) solar PV model was implemented to obtain an accurate sizing of the proposed system. For instance, the best solution of the third case is held at TNPC of 64.504 million USD/yr and IR of 96.048%. These findings were revealed at 33,459 panels and 12.498 h/day. Further, system emissions for each scenario have been tested. Finally, decision makers are invited to adopt to the findings and energy management strategy of this paper to find reliable and cost-effective best solutions. Full article
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17 pages, 3754 KiB  
Article
Forest Regeneration Patterns Differ Considerably between Sites with and without Windthrow Wood Logging in the High Tatra Mountains
by Bohdan Konôpka, Vladimír Šebeň and Katarína Merganičová
Forests 2021, 12(10), 1349; https://doi.org/10.3390/f12101349 - 2 Oct 2021
Cited by 10 | Viewed by 2591
Abstract
Our research focused on the impact of post-disturbance management on the subsequent forest stands in the territory of the High Tatra Mts. situated in the northern part of Slovakia. The field work was carried out within the post-disturbance area in 2019, i.e., 15 [...] Read more.
Our research focused on the impact of post-disturbance management on the subsequent forest stands in the territory of the High Tatra Mts. situated in the northern part of Slovakia. The field work was carried out within the post-disturbance area in 2019, i.e., 15 years after the windstorm. In total, we used data from 80 monitoring plots (MP): 40 plots situated inside the managed part and 40 in the unmanaged areas. Post-disturbance management specifically consisted of logging of wind-thrown wood; therefore, the main difference between the two areas (salvaged versus unsalvaged) was the amount of coarse woody debris (CWD) left on site. We focused on the characteristics of newly regenerated forest stands: the number of trees and tree species per MP, tree height and browsing (mostly by red deer, Cervus elaphus) were recorded as was their growth substrate, i.e., soil or CWD. Higher tree densities, larger trees as well as higher tree species richness were found at salvaged plots. In addition, more evident dominance of Norway spruce (Picea abies (L) Karst.) was recorded at unsalvaged plots. Common rowans (Sorbus aucuparia L.) were frequent at both plot types. Birch trees (Betula sp.) were very frequent at salvaged plots, while only a few birch individuals were recorded at unsalvaged ones. The proportion of trees growing on CWD was 15% at unsalvaged and 3% at salvaged plots. Trees growing on the soil contained nearly double the aboveground biomass than those on CWD. Red deer browsing was approximately two times more frequent at salvaged than unsalvaged plots. While rowan was extremely prone to browsing, spruce was damaged negligibly. These main findings could have two contradictory conclusions, the positive one being that differentiated post-disturbance management within a certain area can combine both forestry and nature conservation interests. Moreover, it can generate parallel forests with different properties that might positively influence the future stability of forest ecosystems as a whole. The negative side might be that contrasting post-disturbance management can cause an uneven distribution of red deer population and intensive browsing in areas favourable for game. Full article
(This article belongs to the Section Forest Ecology and Management)
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20 pages, 5980 KiB  
Article
Numerical Investigation of Latent Thermal Storage in a Compact Heat Exchanger Using Mini-Channels
by Amir Abdi, Justin Ningwei Chiu and Viktoria Martin
Appl. Sci. 2021, 11(13), 5985; https://doi.org/10.3390/app11135985 - 27 Jun 2021
Cited by 2 | Viewed by 1883
Abstract
This paper aims to numerically investigate the thermal enhancement of a latent thermal energy storage component with mini-channels as air passages. The investigated channels in two sizes of internal air passages (channel-1 with dh = 1.6 mm and channel-2 with dh [...] Read more.
This paper aims to numerically investigate the thermal enhancement of a latent thermal energy storage component with mini-channels as air passages. The investigated channels in two sizes of internal air passages (channel-1 with dh = 1.6 mm and channel-2 with dh = 2.3 mm) are oriented vertically in a cuboid of 0.15 × 0.15 × 0.1 m3 with RT22 as the PCM located in the shell. The phase change is simulated with a fixed inlet temperature of air, using ANSYS Fluent 19.5, with a varying number of channels and a ranging air flow rate entering the component. The results show that the phase change power of the LTES improves with by increasing the number of channels at the cost of a decrease in the storage capacity. Given a constant air flow rate, the increase in the heat transfer surface area of the increased number of channels dominates the heat transfer coefficient, thus increasing the mean heat transfer rate (UA). A comparison of the channels shows that the thermal performance depends largely on the area to volume ratio of the channels. The channel type two (channel-2) with a slightly higher area to volume ratio has a slightly higher charging/discharging power, as compared to channel type one (channel-1), at a similar PCM packing factor. Adding fins to channel-2, doubling the surface area, improves the mean UA values by 15–31% for the studied cases. The variation in the total air flow rate from 7 to 24 L/s is found to have a considerable influence, reducing the melting time by 41–53% and increasing the mean UA values within melting by 19–52% for a packing factor range of 77.4–86.8%. With the increase in the air flow rate, channel type two is found to have considerably lower pressure drops than channel type one, which can be attributed to its higher internal hydraulic diameter, making it superior in terms of achieving a relatively similar charging/discharging power in exchange for significantly lower fan power. Such designs can further be optimized in terms of pressure drop in future work, which should also include an experimental evaluation. Full article
(This article belongs to the Special Issue Phase Change Materials: Design and Applications)
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