期刊文献+
共找到127,374篇文章
< 1 2 250 >
每页显示 20 50 100
LOCAL C-SEMIGROUPS AND LOCAL C-COSINE FUNCTIONS 被引量:1
1
作者 高明杵 《Acta Mathematica Scientia》 SCIE CSCD 1999年第2期201-213,共13页
This paper is concerned with the local C-semigroups and local C-cosine functions without the assumption that the image of C is dense in a Banach space X, First, the sufficient and necessary conditions for a local C-se... This paper is concerned with the local C-semigroups and local C-cosine functions without the assumption that the image of C is dense in a Banach space X, First, the sufficient and necessary conditions for a local C-semigroup and a C-cosine function to be the restriction of a global C-semigroup and a global C-cosine function to an interval are given, respectively, Secondly, it is characterized for a closed operator to be the generator of a local C-semigroup and a local C-cosine function, respectively. 展开更多
关键词 local c-semigroups local C-cosine functions asymptotic C-resolvent
在线阅读 下载PDF
ADDITIVE PERTURBATIONS OF LOCAL C-SEMIGROUPS 被引量:1
2
作者 Chung-Cheng KUO 《Acta Mathematica Scientia》 SCIE CSCD 2015年第6期1566-1576,共11页
In this paper, we apply the contraction mapping theorem to establish some bounded and unbounded additive perturbation theorems concerning local C-semigroups. Some growth conditions of perturbations of local C-semigrou... In this paper, we apply the contraction mapping theorem to establish some bounded and unbounded additive perturbation theorems concerning local C-semigroups. Some growth conditions of perturbations of local C-semigroups axe also established. 展开更多
关键词 local c-semigroup generator abstract Cauchy problem PERTURBATION
在线阅读 下载PDF
MULTIPLICATIVE PERTURBATIONS OF LOCAL α-TIMES INTEGRATED C-SEMIGROUPS 被引量:1
3
作者 Nai-Sher YEH Chung-Cheng KUO 《Acta Mathematica Scientia》 SCIE CSCD 2017年第3期877-888,共12页
We establish some left and right multiplicative perturbations of a local α-timesintegrated C-semigroup S(·) on a complex Banach space X with non-densely defined genera- tor, which can be applied to obtain some... We establish some left and right multiplicative perturbations of a local α-timesintegrated C-semigroup S(·) on a complex Banach space X with non-densely defined genera- tor, which can be applied to obtain some additive perturbation results concerning S(·). Some growth conditions of the perturbations of S(·) are also established. 展开更多
关键词 Integrated c-semigroup generator abstract Cauchy problem PERTURBATION
在线阅读 下载PDF
Navigating the pathways:TAR-DNA-binding-protein-43 aggregation,axonal transport,and local synthesis in amyotrophic lateral sclerosis pathology
4
作者 Ori Bar Avi Eran Perlson 《Neural Regeneration Research》 SCIE CAS 2025年第10期2921-2922,共2页
Neurons are highly polarized cells with axons reaching over a meter long in adult humans.To survive and maintain their proper function,neurons depend on specific mechanisms that regulate spatiotemporal signaling and m... Neurons are highly polarized cells with axons reaching over a meter long in adult humans.To survive and maintain their proper function,neurons depend on specific mechanisms that regulate spatiotemporal signaling and metabolic events,which need to be carried out at the right place,time,and intensity.Such mechanisms include axonal transport,local synthesis,and liquid-liquid phase separations.Alterations and malfunctions in these processes are correlated to neurodegenerative diseases such as amyotrophic lateral sclerosis(ALS). 展开更多
关键词 SYNTHESIS local AGGREGATION
在线阅读 下载PDF
LiDAR-Visual SLAM with Integrated Semantic and Texture Information for Enhanced Ecological Monitoring Vehicle Localization
5
作者 Yiqing Lu Liutao Zhao Qiankun Zhao 《Computers, Materials & Continua》 SCIE EI 2025年第1期1401-1416,共16页
Ecological monitoring vehicles are equipped with a range of sensors and monitoring devices designed to gather data on ecological and environmental factors.These vehicles are crucial in various fields,including environ... Ecological monitoring vehicles are equipped with a range of sensors and monitoring devices designed to gather data on ecological and environmental factors.These vehicles are crucial in various fields,including environmental science research,ecological and environmental monitoring projects,disaster response,and emergency management.A key method employed in these vehicles for achieving high-precision positioning is LiDAR(lightlaser detection and ranging)-Visual Simultaneous Localization and Mapping(SLAM).However,maintaining highprecision localization in complex scenarios,such as degraded environments or when dynamic objects are present,remains a significant challenge.To address this issue,we integrate both semantic and texture information from LiDAR and cameras to enhance the robustness and efficiency of data registration.Specifically,semantic information simplifies the modeling of scene elements,reducing the reliance on dense point clouds,which can be less efficient.Meanwhile,visual texture information complements LiDAR-Visual localization by providing additional contextual details.By incorporating semantic and texture details frompaired images and point clouds,we significantly improve the quality of data association,thereby increasing the success rate of localization.This approach not only enhances the operational capabilities of ecological monitoring vehicles in complex environments but also contributes to improving the overall efficiency and effectiveness of ecological monitoring and environmental protection efforts. 展开更多
关键词 LiDAR-Visual simultaneous localization and mapping integrated semantic texture information
在线阅读 下载PDF
Understanding the local structure and thermophysical behavior of Mg-La liquid alloys via machine learning potential
6
作者 Jia Zhao Taixi Feng Guimin Lu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS 2025年第2期439-449,共11页
The local structure and thermophysical behavior of Mg-La liquid alloys were in-depth understood using deep potential molecular dynamic(DPMD) simulation driven via machine learning to promote the development of Mg-La a... The local structure and thermophysical behavior of Mg-La liquid alloys were in-depth understood using deep potential molecular dynamic(DPMD) simulation driven via machine learning to promote the development of Mg-La alloys. The robustness of the trained deep potential(DP) model was thoroughly evaluated through several aspects, including root-mean-square errors(RMSEs), energy and force data, and structural information comparison results;the results indicate the carefully trained DP model is reliable. The component and temperature dependence of the local structure in the Mg-La liquid alloy was analyzed. The effect of Mg content in the system on the first coordination shell of the atomic pairs is the same as that of temperature. The pre-peak demonstrated in the structure factor indicates the presence of a medium-range ordered structure in the Mg-La liquid alloy, which is particularly pronounced in the 80at% Mg system and disappears at elevated temperatures. The density, self-diffusion coefficient, and shear viscosity for the Mg-La liquid alloy were predicted via DPMD simulation, the evolution patterns with Mg content and temperature were subsequently discussed, and a database was established accordingly. Finally, the mixing enthalpy and elemental activity of the Mg-La liquid alloy at 1200 K were reliably evaluated,which provides new guidance for related studies. 展开更多
关键词 magnesium-lanthanum liquid alloys local structure macroscopic properties thermodynamic behavior deep potential mo-lecular dynamic simulation
在线阅读 下载PDF
Morphological Characteristics of Local Chicken Populations (Gallus gallus domesticus) in Farmed Basins of the Far North Region, Cameroon
7
作者 Christophe Wang-baa Temoa Jean Massawa +2 位作者 Francis Dongmo Djiotsa Yakouba Manjely Felix Meutchieye 《Open Journal of Animal Sciences》 2025年第1期51-68,共18页
In order to contribute to a better understanding of the biodiversity of local chicken populations, this study focused on the description of the essential qualitative parameters in the phenotypic characterization of lo... In order to contribute to a better understanding of the biodiversity of local chicken populations, this study focused on the description of the essential qualitative parameters in the phenotypic characterization of local species. Conducted in 6 localities in the Far North Region of Cameroon (Doukoula, Yagoua, Guidiguis, Dziguilao, Maroua 3rd and Méri), a population of 240 local chickens, including 172 hens and 68 cocks were characterized in family farms. The choice of localities was made on the basis of their strong potential local chicken flocks in the region. To this end, each animal was the subject of a qualitative description based on the identification of the sex of the animal, the description of the colorations of the plumage and extremities, and the description of the types of format, plumage and crests. All observations were made with the naked eye and in daylight and then photographed. The main results show that the plumage colors are multiple and dominated by the White-Pied-Black (21.7%) and the Mille-fleur (20.8%);the wattles are dominated by the red (60%) and the pink (35.4%);the tarsi are dominated by the white (43.8%) and the black (32.08%);the white skin (92.5%) dominates over the pink skin (7.5%);the “Smooth-uniform” feather is dominant (97.08%), followed by the smooth-crested type (2.08%) and the fries type (0.82%);the medium size of the chickens is dominant (86.66%), followed by the dwarf size (9.58%) and the large size (3.75%). The results of this study demonstrate that there is a strong phenotypic diversity within the local chicken population. This diversity can serve as a basis for the development of selection, conservation and genetic potential improvement programs based on rational exploitation of the local chicken. 展开更多
关键词 Morphological Characteristics local Chicken Far North Cameroon
在线阅读 下载PDF
Assessment of Local Substrates from Burkina Faso for the Growth of Entomopathogenic Fungi Metarhizium pingshaense for Malaria Vector Control Perspectives
8
作者 Issiaka Sare Carine Letitia Traore +2 位作者 Armel Judicael Lingani Abdoulaye Diabate Etienne Bilgo 《Advances in Microbiology》 2025年第2期126-135,共10页
Malaria is a potentially lethal disease caused by parasites of the Plasmodium genus, transmitted to humans through the bite of infected female mosquitoes, primarily Anopheles. To control this disease, various strategi... Malaria is a potentially lethal disease caused by parasites of the Plasmodium genus, transmitted to humans through the bite of infected female mosquitoes, primarily Anopheles. To control this disease, various strategies are implemented, including biological control, which targets the vectors of the parasite. This approach uses biological agents such as entomopathogenic fungi, including Metarhizium pingshaense, a fungus capable of causing lethal infections in mosquitoes. The production of Metarhizium pingshaense is still limited in Burkina Faso, and local cultivation of this fungus could help fill this gap. A study was conducted to identify optimal local substrates that promote its growth. Indeed, after gathering information on the dietary habits of populations in Bobo-Dioulasso and Bama, three potential substrates were selected: rice, cornmeal dough (MFL), and beans. These substrates were inoculated with two strains of Metarhizium pingshaense (S10 and S26) to assess their ability to support fungal growth and their effectiveness. Experimental results showed that MFL and bean substrates favored optimal growth of Metarhizium pingshaense, with growths of 1.91 cm and 2.13 cm after 8 days, compared to 1.83 cm on a standard media (PDA). In terms of virulence, S26 strain caused 60% mosquito mortality on both the bean and PDA media, while S10 strain induced mortalities of 50% for bean and 62% for PDA. 展开更多
关键词 MALARIA ANOPHELES Biological Control Metarhizium pingshaense local Culture Media Burkina Faso
在线阅读 下载PDF
SNR and RSSI Based an Optimized Machine Learning Based Indoor Localization Approach:Multistory Round Building Scenario over LoRa Network 被引量:1
9
作者 Muhammad Ayoub Kamal Muhammad Mansoor Alam +1 位作者 Aznida Abu Bakar Sajak Mazliham Mohd Su’ud 《Computers, Materials & Continua》 SCIE EI 2024年第8期1927-1945,共19页
In situations when the precise position of a machine is unknown,localization becomes crucial.This research focuses on improving the position prediction accuracy over long-range(LoRa)network using an optimized machine ... In situations when the precise position of a machine is unknown,localization becomes crucial.This research focuses on improving the position prediction accuracy over long-range(LoRa)network using an optimized machine learning-based technique.In order to increase the prediction accuracy of the reference point position on the data collected using the fingerprinting method over LoRa technology,this study proposed an optimized machine learning(ML)based algorithm.Received signal strength indicator(RSSI)data from the sensors at different positions was first gathered via an experiment through the LoRa network in a multistory round layout building.The noise factor is also taken into account,and the signal-to-noise ratio(SNR)value is recorded for every RSSI measurement.This study concludes the examination of reference point accuracy with the modified KNN method(MKNN).MKNN was created to more precisely anticipate the position of the reference point.The findings showed that MKNN outperformed other algorithms in terms of accuracy and complexity. 展开更多
关键词 Indoor localization MKNN LoRa machine learning classification RSSI SNR localization
在线阅读 下载PDF
SUBGENERATORS OF C-SEMIGROUPS ON l^2
10
作者 Jine Shi Sufen Cai 《Analysis in Theory and Applications》 2009年第3期297-300,共4页
This paper gives some results about the subgenerators of special C-semigroups on l^2, partly answers the problem mentioned in [1].
关键词 c-semigroup GENERATOR subgenerator the smallest subgenerator
在线阅读 下载PDF
Approximation Theoretic Aspects of Probabilistic Representations for Bi-continuous C-semigroups
11
作者 Cang Ding-bang Chen Cang +1 位作者 Song Xiao-qiu Ji You-qing 《Communications in Mathematical Research》 CSCD 2014年第2期106-116,共11页
By means of Riemann-Stieltjes stochastic process, moment-generating functions and operator-valued mathematical expectation, the problem of probabilistic approximation for bi-continuous C-semigroups is studied and the ... By means of Riemann-Stieltjes stochastic process, moment-generating functions and operator-valued mathematical expectation, the problem of probabilistic approximation for bi-continuous C-semigroups is studied and the general probabilistic approximation of exponential formulas and the generation theorems are given. 展开更多
关键词 bi-continuous c-semigroup probabilistic approximation generationtheorem
在线阅读 下载PDF
A study of the effect of local scour on the flow field near the spur dike 被引量:2
12
作者 Yu-Tian Li Jie-Min Zhan Wing-Hong Onyx Wai 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2024年第2期98-105,共8页
The flow field near a spur dike such as down flow and horseshoe vortex system(HVS)are susceptible to the topographic changes in the local scouring process,resulting in variation of the sediment transport with time.In ... The flow field near a spur dike such as down flow and horseshoe vortex system(HVS)are susceptible to the topographic changes in the local scouring process,resulting in variation of the sediment transport with time.In this study,large eddy simulations with fixed-bed at different scouring stages were conducted to investigate the changes in flow field.The results imply that the bed deformation leads to an increase in flow rate per unit area,which represent the capability of sediment transportation by water,in the scour hole.Moreover,the intensity of turbulent kinetic energy and bimodal motion near the sand bed induced by the HVS were also varied.However,the peak moments between the two sediment transport mechanisms were different.Hence,understanding the complex feedback mechanism between topography and flow field is essential for the local scour problem. 展开更多
关键词 Spur dike local scour Large eddy simulation Down flow Horseshoe vortex system
在线阅读 下载PDF
THE EXPONENTIAL-TYPE REPRESENTATION FORMULAS FOR C-SEMIGROUPS
13
作者 Chen Wenzhoug(Xiamen University, China) 《Analysis in Theory and Applications》 1995年第1期43-53,共11页
Some exponential type representation formulas for C-semigroups are given in Banach space. Moreover, we obtain a corresponding Voronovskaja - type asymptotic formula.
关键词 LIM THE EXPONENTIAL-TYPE REPRESENTATION FORMULAS FOR c-semigroups
在线阅读 下载PDF
Genome-wide investigation to assess copy number variants in the Italian local chicken population 被引量:1
14
作者 Filippo Cendron Martino Cassandro Mauro Penasa 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2024年第2期563-577,共15页
Background Copy number variants(CNV)hold significant functional and evolutionary importance.Numerous ongoing CNV studies aim to elucidate the etiology of human diseases and gain insights into the population structure ... Background Copy number variants(CNV)hold significant functional and evolutionary importance.Numerous ongoing CNV studies aim to elucidate the etiology of human diseases and gain insights into the population structure of livestock.High-density chips have enabled the detection of CNV with increased resolution,leading to the identification of even small CNV.This study aimed to identify CNV in local Italian chicken breeds and investigate their distribution across the genome.Results Copy number variants were mainly distributed across the first six chromosomes and primarily associated with loss type CNV.The majority of CNV in the investigated breeds were of types 0 and 1,and the minimum length of CNV was significantly larger than that reported in previous studies.Interestingly,a high proportion of the length of chromosome 16 was covered by copy number variation regions(CNVR),with the major histocompatibility complex being the likely cause.Among the genes identified within CNVR,only those present in at least five animals across breeds(n=95)were discussed to reduce the focus on redundant CNV.Some of these genes have been associated to functional traits in chickens.Notably,several CNVR on different chromosomes harbor genes related to muscle development,tissue-specific biological processes,heat stress resistance,and immune response.Quantitative trait loci(QTL)were also analyzed to investigate potential overlapping with the identified CNVR:54 out of the 95 gene-containing regions overlapped with 428 QTL associated to body weight and size,carcass characteristics,egg production,egg components,fat deposition,and feed intake.Conclusions The genomic phenomena reported in this study that can cause changes in the distribution of CNV within the genome over time and the comparison of these differences in CNVR of the local chicken breeds could help in preserving these genetic resources. 展开更多
关键词 CHICKEN Copy number variant CONSERVATION local breed SNP
在线阅读 下载PDF
Present situation and prospect of immunotherapy for unresectable locally advanced esophageal cancer during peri-radiotherapy 被引量:1
15
作者 Feng-Mei Wang Peng Mo +2 位作者 Xue Yan Xin-Yue Lin Zhi-Chao Fu 《World Journal of Gastrointestinal Oncology》 SCIE 2024年第1期1-7,共7页
Four major studies(Checkmate577,Keynote-590,Checkmate649 and Attraction-4)of locally advanced esophageal cancer published in 2020 have established the importance of immunotherapy,represented by anti-programmed death p... Four major studies(Checkmate577,Keynote-590,Checkmate649 and Attraction-4)of locally advanced esophageal cancer published in 2020 have established the importance of immunotherapy,represented by anti-programmed death protein(PD)-1 in postoperative adjuvant treatment and advanced first-line treatment of locally advanced or advanced esophageal cancer and esophagogastric junction cancer,from the aspects of proof of concept,long-term survival,overall survival rate and progression-free survival.For unresectable or inoperable nonmetastatic esophageal cancer,concurrent radiotherapy and chemotherapy is the standard treatment recommended by various guidelines.Because its curative effect is still not ideal,it is necessary to explore radical radiotherapy and chemotherapy in the future,and it is considered to be promising to combine them with immunotherapeutic drugs such as anti-PD-1.This paper mainly discusses how to combine radical concurrent radiotherapy and chemotherapy with immunotherapy for unresectable local advanced esophageal cancer. 展开更多
关键词 Esophageal carcinoma locally advanced RADIOTHERAPY IMMUNOTHERAPY
在线阅读 下载PDF
Scheme Based on Multi-Level Patch Attention and Lesion Localization for Diabetic Retinopathy Grading 被引量:1
16
作者 Zhuoqun Xia Hangyu Hu +4 位作者 Wenjing Li Qisheng Jiang Lan Pu Yicong Shu Arun Kumar Sangaiah 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第7期409-430,共22页
Early screening of diabetes retinopathy(DR)plays an important role in preventing irreversible blindness.Existing research has failed to fully explore effective DR lesion information in fundus maps.Besides,traditional ... Early screening of diabetes retinopathy(DR)plays an important role in preventing irreversible blindness.Existing research has failed to fully explore effective DR lesion information in fundus maps.Besides,traditional attention schemes have not considered the impact of lesion type differences on grading,resulting in unreasonable extraction of important lesion features.Therefore,this paper proposes a DR diagnosis scheme that integrates a multi-level patch attention generator(MPAG)and a lesion localization module(LLM).Firstly,MPAGis used to predict patches of different sizes and generate a weighted attention map based on the prediction score and the types of lesions contained in the patches,fully considering the impact of lesion type differences on grading,solving the problem that the attention maps of lesions cannot be further refined and then adapted to the final DR diagnosis task.Secondly,the LLM generates a global attention map based on localization.Finally,the weighted attention map and global attention map are weighted with the fundus map to fully explore effective DR lesion information and increase the attention of the classification network to lesion details.This paper demonstrates the effectiveness of the proposed method through extensive experiments on the public DDR dataset,obtaining an accuracy of 0.8064. 展开更多
关键词 DDR dataset diabetic retinopathy lesion localization multi-level patch attention mechanism
在线阅读 下载PDF
Deep brain implantable microelectrode arrays for detection and functional localization of the subthalamic nucleus in rats with Parkinson’s disease 被引量:1
17
作者 Luyi Jing Zhaojie Xu +11 位作者 Penghui Fan Botao Lu Fan Mo Ruilin Hu Wei Xu Jin Shan Qianli Jia Yuxin Zhu Yiming Duan Mixia Wang Yirong Wu Xinxia Cai 《Bio-Design and Manufacturing》 SCIE EI CAS CSCD 2024年第4期439-452,共14页
The subthalamic nucleus(STN)is considered the best target for deep brain stimulation treatments of Parkinson’s disease(PD).It is difficult to localize the STN due to its small size and deep location.Multichannel micr... The subthalamic nucleus(STN)is considered the best target for deep brain stimulation treatments of Parkinson’s disease(PD).It is difficult to localize the STN due to its small size and deep location.Multichannel microelectrode arrays(MEAs)can rapidly and precisely locate the STN,which is important for precise stimulation.In this paper,16-channel MEAs modified with multiwalled carbon nanotube/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(MWCNT/PEDOT:PSS)nanocomposites were designed and fabricated,and the accurate and rapid identification of the STN in PD rats was performed using detection sites distributed at different brain depths.These results showed that nuclei in 6-hydroxydopamine hydrobromide(6-OHDA)-lesioned brains discharged more intensely than those in unlesioned brains.In addition,the MEA simultaneously acquired neural signals from both the STN and the upper or lower boundary nuclei of the STN.Moreover,higher values of spike firing rate,spike amplitude,local field potential(LFP)power,and beta oscillations were detected in the STN of the 6-OHDA-lesioned brain,and may therefore be biomarkers of STN localization.Compared with the STNs of unlesioned brains,the power spectral density of spikes and LFPs synchronously decreased in the delta band and increased in the beta band of 6-OHDA-lesioned brains.This may be a cause of sleep and motor disorders associated with PD.Overall,this work describes a new cellular-level localization and detection method and provides a tool for future studies of deep brain nuclei. 展开更多
关键词 Functional localization Implantable microelectrode arrays Parkinson’s disease Subthalamic nucleus
在线阅读 下载PDF
Cooperative Anti-Jamming and Interference Mitigation for UAV Networks: A Local Altruistic Game Approach 被引量:2
18
作者 Yueyue Su Nan Qi +2 位作者 Zanqi Huang Rugui Yao Luliang Jia 《China Communications》 SCIE CSCD 2024年第2期183-196,共14页
To improve the anti-jamming and interference mitigation ability of the UAV-aided communication systems, this paper investigates the channel selection optimization problem in face of both internal mutual interference a... To improve the anti-jamming and interference mitigation ability of the UAV-aided communication systems, this paper investigates the channel selection optimization problem in face of both internal mutual interference and external malicious jamming. A cooperative anti-jamming and interference mitigation method based on local altruistic is proposed to optimize UAVs’ channel selection. Specifically, a Stackelberg game is modeled to formulate the confrontation relationship between UAVs and the jammer. A local altruistic game is modeled with each UAV considering the utilities of both itself and other UAVs. A distributed cooperative anti-jamming and interference mitigation algorithm is proposed to obtain the Stackelberg equilibrium. Finally, the convergence of the proposed algorithm and the impact of the transmission power on the system loss value are analyzed, and the anti-jamming performance of the proposed algorithm can be improved by around 64% compared with the existing algorithms. 展开更多
关键词 channel selection cooperative antijamming and interference mitigation local altruistic game Stackelberg game unmanned aerial vehicle(UAV)
在线阅读 下载PDF
Numerical study on local scour characteristics around submarine pipelines in the Yellow River Delta silty sandy soil under waves and currents 被引量:1
19
作者 Peng Yu Ruigeng Hu +4 位作者 Jike Zhang Qi Yang Jieru Zhao Lei Cao Chenghao Zhu 《Deep Underground Science and Engineering》 2024年第2期182-196,共15页
Due to their high reliability and cost-efficiency,submarine pipelines are widely used in offshore oil and gas resource engineering.Due to the interaction of waves,currents,seabed,and pipeline structures,the soil aroun... Due to their high reliability and cost-efficiency,submarine pipelines are widely used in offshore oil and gas resource engineering.Due to the interaction of waves,currents,seabed,and pipeline structures,the soil around submarine pipelines is prone to local scour,severely affecting their operational safety.With the Yellow River Delta as the research area and based on the renormalized group(RNG)k-εturbulence model and Stokes fifth-order wave theory,this study solves the Navier-Stokes(N-S)equation using the finite difference method.The volume of fluid(VOF)method is used to describe the fluid-free surface,and a threedimensional numerical model of currents and waves-submarine pipeline-silty sandy seabed is established.The rationality of the numerical model is verified using a self-built waveflow flume.On this basis,in this study,the local scour development and characteristics of submarine pipelines in the Yellow River Delta silty sandy seabed in the prototype environment are explored and the influence of the presence of pipelines on hydrodynamic features such as surrounding flow field,shear stress,and turbulence intensity is analyzed.The results indicate that(1)local scour around submarine pipelines can be divided into three stages:rapid scour,slow scour,and stable scour.The maximum scour depth occurs directly below the pipeline,and the shape of the scour pits is asymmetric.(2)As the water depth decreases and the pipeline suspension height increases,the scour becomes more intense.(3)When currents go through a pipeline,a clear stagnation point is formed in front of the pipeline,and the flow velocity is positively correlated with the depth of scour.This study can provide a valuable reference for the protection of submarine pipelines in this area. 展开更多
关键词 local scour numerical simulation submarine pipelines Yellow River Delta
在线阅读 下载PDF
Life cycle assessment as a prospective tool for sustainable agriculture and food planning at a local level 被引量:1
20
作者 Andrea Lulovicova Stephane Bouissou 《Geography and Sustainability》 CSCD 2024年第2期251-264,共14页
Owing to the far-reaching environmental consequences of agriculture and food systems,such as their contribution to climate change,there is an urgent need to reduce their impact.International and national governments s... Owing to the far-reaching environmental consequences of agriculture and food systems,such as their contribution to climate change,there is an urgent need to reduce their impact.International and national governments set sustainability targets and implement corresponding measures.Nevertheless,critics of the globalized system claim that a territorial administrative scale is better suited to address sustainability issues.Yet,at the subnational level,local authorities rarely apply a systemic environmental assessment to enhance their action plans.This paper employs a territorial life cycle assessment methodology to improve local environmental agri-food planning.The objective is to identify significant direct and indirect environmental hotspots,their origins,and formulate effective mitigation strategies.The methodology is applied to the administrative department of Finistere,a strategic agricultural region in North-Western France.Multiple environmental criteria including climate change,fossil resource scarcity,toxicity,and land use are modeled.The findings reveal that the primary environmental hotspots of the studied local food system arise from indirect sources,such as livestock feed or diesel consumption.Livestock reduction and organic farming conversion emerge as the most environmentally efficient strategies,resulting in a 25%decrease in the climate change indicator.However,the overall modeled impact reduction is insufficient following national objectives and remains limited for the land use indicator.These results highlight the innovative application of life cycle assessment led at a local level,offering insights for the further advancement of systematic and prospective local agri-food assessment.Additionally,they provide guidance for local authorities to enhance the sustainability of planning strategies. 展开更多
关键词 Environmental analysis Territorial life cycle assessment Prospective scenario Agri-food planning local food system
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部