期刊文献+
共找到102,488篇文章
< 1 2 250 >
每页显示 20 50 100
Sustained release of vascular endothelial growth factor A and basic fibroblast growth factor from nanofiber membranes reduces oxygen/glucose deprivation-induced injury to neurovascular units 被引量:2
1
作者 Yifang Wu Jun Sun +2 位作者 Qi Lin Dapeng Wang Jian Hai 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第4期887-894,共8页
Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell... Upregulation of vascular endothelial growth factor A/basic fibroblast growth factor(VEGFA/b FGF)expression in the penumbra of cerebral ischemia can increase vascular volume,reduce lesion volume,and enhance neural cell proliferation and differentiation,thereby exerting neuroprotective effects.However,the beneficial effects of endogenous VEGFA/b FGF are limited as their expression is only transiently increased.In this study,we generated multilayered nanofiber membranes loaded with VEGFA/b FGF using layer-by-layer self-assembly and electrospinning techniques.We found that a membrane containing 10 layers had an ideal ultrastructure and could efficiently and stably release growth factors for more than 1 month.This 10-layered nanofiber membrane promoted brain microvascular endothelial cell tube formation and proliferation,inhibited neuronal apoptosis,upregulated the expression of tight junction proteins,and improved the viability of various cellular components of neurovascular units under conditions of oxygen/glucose deprivation.Furthermore,this nanofiber membrane decreased the expression of Janus kinase-2/signal transducer and activator of transcription-3(JAK2/STAT3),Bax/Bcl-2,and cleaved caspase-3.Therefore,this nanofiber membrane exhibits a neuroprotective effect on oxygen/glucose-deprived neurovascular units by inhibiting the JAK2/STAT3 pathway. 展开更多
关键词 brain ischemia brain microvascular endothelial cell nanofiber membrane neurovascular unit
下载PDF
Assessment of Wet Season Precipitation in the Central United States by the Regional Climate Simulation of the WRFG Member in NARCCAP and Its Relationship with Large-Scale Circulation Biases 被引量:1
2
作者 Yating ZHAO Ming XUE +2 位作者 Jing JIANG Xiao-Ming HU Anning HUANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第4期619-638,共20页
Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss pos... Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional climate.Here,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are available.The RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of precipitation.This dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the simulation.Inaccuracy in reproducing large-scale circulation and environmental conditions is another contributing factor.The too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great Plains.The simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as well.Therefore,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios. 展开更多
关键词 NARCCAP Central united States PRECIPITATION low-level jet large-scale environment diurnal variation
下载PDF
A gated recurrent unit model to predict Poisson’s ratio using deep learning 被引量:1
3
作者 Fahd Saeed Alakbari Mysara Eissa Mohyaldinn +4 位作者 Mohammed Abdalla Ayoub Ibnelwaleed A.Hussein Ali Samer Muhsan Syahrir Ridha Abdullah Abduljabbar Salih 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第1期123-135,共13页
Static Poisson’s ratio(vs)is crucial for determining geomechanical properties in petroleum applications,namely sand production.Some models have been used to predict vs;however,the published models were limited to spe... Static Poisson’s ratio(vs)is crucial for determining geomechanical properties in petroleum applications,namely sand production.Some models have been used to predict vs;however,the published models were limited to specific data ranges with an average absolute percentage relative error(AAPRE)of more than 10%.The published gated recurrent unit(GRU)models do not consider trend analysis to show physical behaviors.In this study,we aim to develop a GRU model using trend analysis and three inputs for predicting n s based on a broad range of data,n s(value of 0.1627-0.4492),bulk formation density(RHOB)(0.315-2.994 g/mL),compressional time(DTc)(44.43-186.9 μs/ft),and shear time(DTs)(72.9-341.2μ s/ft).The GRU model was evaluated using different approaches,including statistical error an-alyses.The GRU model showed the proper trends,and the model data ranges were wider than previous ones.The GRU model has the largest correlation coefficient(R)of 0.967 and the lowest AAPRE,average percent relative error(APRE),root mean square error(RMSE),and standard deviation(SD)of 3.228%,1.054%,4.389,and 0.013,respectively,compared to other models.The GRU model has a high accuracy for the different datasets:training,validation,testing,and the whole datasets with R and AAPRE values were 0.981 and 2.601%,0.966 and 3.274%,0.967 and 3.228%,and 0.977 and 2.861%,respectively.The group error analyses of all inputs show that the GRU model has less than 5% AAPRE for all input ranges,which is superior to other models that have different AAPRE values of more than 10% at various ranges of inputs. 展开更多
关键词 Static Poisson’s ratio Deep learning Gated recurrent unit(GRU) Sand control Trend analysis Geomechanical properties
下载PDF
基于Unity3D的油田抽油机三维可视化监控系统设计 被引量:2
4
作者 刘立强 孙文磊 +1 位作者 王一 王炳楷 《系统仿真学报》 CAS CSCD 北大核心 2024年第2期463-475,共13页
针对抽油机监测形式单一、三维可视化程度低和联动性差的缺陷,引入信息―物理实时映射思想,开发了油田抽油机三维可视化监控系统。设计了抽油机数字空间,搭建虚实交互层设计架构;搭建三维可视化系统数据组成及关系框架;结合逆运动学,构... 针对抽油机监测形式单一、三维可视化程度低和联动性差的缺陷,引入信息―物理实时映射思想,开发了油田抽油机三维可视化监控系统。设计了抽油机数字空间,搭建虚实交互层设计架构;搭建三维可视化系统数据组成及关系框架;结合逆运动学,构建数学模型,基于五维模型和Unity 3D平台设计抽油机三维可视化系统总体架构;以游梁式抽油机为对象进行实验验证,实现了实时动态监测、虚实混合控制、运动轨迹追踪和在线预警等服务功能。为三维可视化监控在石油机械领域的落地应用和数字孪生系统的开发提供借鉴。 展开更多
关键词 抽油机 三维可视化 实时动态监测 虚实混合控制 unitY3D
下载PDF
Uncertainties of landslide susceptibility prediction:influences of different study area scales and mapping unit scales
5
作者 Faming Huang Yu Cao +4 位作者 Wenbin Li Filippo Catani Guquan Song Jinsong Huang Changshi Yu 《International Journal of Coal Science & Technology》 EI CAS CSCD 2024年第2期143-172,共30页
This study aims to investigate the effects of different mapping unit scales and study area scales on the uncertainty rules of landslide susceptibility prediction(LSP).To illustrate various study area scales,Ganzhou Ci... This study aims to investigate the effects of different mapping unit scales and study area scales on the uncertainty rules of landslide susceptibility prediction(LSP).To illustrate various study area scales,Ganzhou City in China,its eastern region(Ganzhou East),and Ruijin County in Ganzhou East were chosen.Different mapping unit scales are represented by grid units with spatial resolution of 30 and 60 m,as well as slope units that were extracted by multi-scale segmentation method.The 3855 landslide locations and 21 typical environmental factors in Ganzhou City are first determined to create spatial datasets with input-outputs.Then,landslide susceptibility maps(LSMs)of Ganzhou City,Ganzhou East and Ruijin County are pro-duced using a support vector machine(SVM)and random forest(RF),respectively.The LSMs of the above three regions are then extracted by mask from the LSM of Ganzhou City,along with the LSMs of Ruijin County from Ganzhou East.Additionally,LSMs of Ruijin at various mapping unit scales are generated in accordance.Accuracy and landslide suscepti-bility indexes(LSIs)distribution are used to express LSP uncertainties.The LSP uncertainties under grid units significantly decrease as study area scales decrease from Ganzhou City,Ganzhou East to Ruijin County,whereas those under slope units are less affected by study area scales.Of course,attentions should also be paid to the broader representativeness of large study areas.The LSP accuracy of slope units increases by about 6%–10%compared with those under grid units with 30 m and 60 m resolution in the same study area's scale.The significance of environmental factors exhibits an averaging trend as study area scale increases from small to large.The importance of environmental factors varies greatly with the 60 m grid unit,but it tends to be consistent to some extent in the 30 m grid unit and the slope unit. 展开更多
关键词 Landslide susceptibility prediction Uncertainty analysis Study areas scales Mapping unit scales Slope units Random forest
下载PDF
The neurovascular unit-on-a-chip:modeling ischemic stroke to stem cell therapy
6
作者 Seonghun Kim Minjun Kim +1 位作者 Gerald A.Grant Wonjae Lee 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第7期1431-1432,共2页
The neurovascular unit and stem cell therapy in ischemic stroke:Ischemic stroke,accounts for approximately 85% of all stroke incidents and is a major global health burden.It is the leading cause of disability and deat... The neurovascular unit and stem cell therapy in ischemic stroke:Ischemic stroke,accounts for approximately 85% of all stroke incidents and is a major global health burden.It is the leading cause of disability and death worldwide,posing immense societal and economic challenges due to the long-term care required for stro ke survivors and the significant healthcare costs associated with its treatment and management(Amarenco et al.,2009). 展开更多
关键词 DEATH unit
下载PDF
Risk Factors for Mortality in Acute Kidney Injury in Intensive Care Units in Togo
7
作者 Eyram Makafui Yoan Yawo Amekoudi Kossi Akomola Sabi +3 位作者 Marcel David Keoula Badomta Dolaama Sarakawabalo Assenouwe Tabana Mouzou 《Open Journal of Nephrology》 2024年第1期37-47,共11页
Context: Acute kidney injury (AKI) in intensive care unit (ICU) is common and associated with very high mortality. In Togo, a tropical country with limited resources and only one nephrology department in the north, ac... Context: Acute kidney injury (AKI) in intensive care unit (ICU) is common and associated with very high mortality. In Togo, a tropical country with limited resources and only one nephrology department in the north, acute kidney injury seems to be a real tragedy with high mortality. Aims: to determine risk factors for mortality in acute kidney injury in the intensive care units. Methods and Material: We made a multicentric cross sectional study during 6 months in the four referral centers in northern Togo. Univariate and multivariate logistic regression was used to identify factors associated with mortality. Data were analyzed using RStudio 2023.04.1. Results: A total of 12.6% of patients admitted to intensive care had presented with AKI. The mean age was 49.6 ± 17.9. The sex ratio (M/F) was 2.1. Community-acquired AKI was in the majority (67.7%). Oligo anuria was the most frequent functional sign (38.4%). In our series, 81.6% of patients were in KDIGO stages 2 to 3. AKI was organic in 56.2% of cases. Mortality was 44.3%. In multivariate analysis, the main factors predictive of death were: respiratory distress (OR = 2.36;p Conclusions: Acute kidney injury in intensive care is common in northern Togo, and mortality is high. Identification of associated factors should help anticipate prognosis. 展开更多
关键词 AKI Intensive Care unit DIALYSIS EPIDEMIOLOGY TOGO
下载PDF
A Retrospective Analysis of Intoxicated Patients Admitted to the Intensive Care Unit: A Single-Institution Assessment in the Post-Pandemic Period
8
作者 Müge Arikan Abdullah Yeşilkaya +1 位作者 Büşra Nur Taşdelen İbrahim Özyiğit 《Journal of Biosciences and Medicines》 2024年第3期159-167,共9页
Background: The aim of this study was to evaluate the clinical and epidemiological characteristics of patients with acute intoxication admitted to the Intensive Care Unit (ICU). Material and Methods: An observational ... Background: The aim of this study was to evaluate the clinical and epidemiological characteristics of patients with acute intoxication admitted to the Intensive Care Unit (ICU). Material and Methods: An observational retrospective study was conducted on intoxicated patients who admitted to ICU between January 2022 and January 2024. Data were collected from the patients medical records. The demographic characteristics, causes of intoxications, clinical parameters, the mean stay in the ICU, treatment modalities and prognosis were recorded. Results: A total of 2875 critically ill patients were admitted during the study period, and 109 (3.79%) of them were acute intoxications. Their mean of ages was 38.09 ± 12.29. The female-to-male ratio was 1.37/1. Drugs were found to be the primary cause (62.39%) of intoxications, and analgesics, antidepressants, and antibiotics were the most frequent agents. Suicidal attempts were present in 66 patients, most of them were female (62.13%) and between 17 - 24 years (40.91%). The other common causes of intoxications were carbon monoxide (CO) (22.02%), methyl/ethyl alcohol (8.26%) and mushroom (5.50%). The mean stay in the ICU was 2.69 ± 0.89 days. Mechanical ventilation was applied to 10 of our patients. Renal replacement therapy was required in 6 patients. Despite all treatments, 6 of our patients died, and we found the mortality rate to be 5.50%. Conclusion: Intoxications were more frequent in young female patients and drugs were the most common cause with suicidal intent. Unfortunately, CO poisoning continues to be a very important problem in our city. These findings provided significant information about the characteristics of intoxications in Karabuk. 展开更多
关键词 INTOXICATION Intensive Care unit SUICIDAL MORTALITY
下载PDF
One memristor–one electrolyte-gated transistor-based high energy-efficient dropout neuronal units
9
作者 李亚霖 时凯璐 +4 位作者 朱一新 方晓 崔航源 万青 万昌锦 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第6期569-573,共5页
Artificial neural networks(ANN) have been extensively researched due to their significant energy-saving benefits.Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem. Th... Artificial neural networks(ANN) have been extensively researched due to their significant energy-saving benefits.Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem. This letter reports a dropout neuronal unit(1R1T-DNU) based on one memristor–one electrolyte-gated transistor with an ultralow energy consumption of 25 p J/spike. A dropout neural network is constructed based on such a device and has been verified by MNIST dataset, demonstrating high recognition accuracies(> 90%) within a large range of dropout probabilities up to40%. The running time can be reduced by increasing dropout probability without a significant loss in accuracy. Our results indicate the great potential of introducing such 1R1T-DNUs in full-hardware neural networks to enhance energy efficiency and to solve the overfitting problem. 展开更多
关键词 dropout neuronal unit synaptic transistors MEMRISTOR artificial neural network
下载PDF
Analysis of the Erosion-Corrosion Mechanism of the Air Cooler in a Hydrocracking Unit:A Numerical and Experimental Study
10
作者 Su Guoqing Li Yan +1 位作者 Guo Hongli Zhang Jianwen 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2024年第1期126-138,共13页
Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirm... Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirmed that the damage was caused by erosion-corrosion(E-C).Numerical and experimental methods were applied to investigate the E-C mechanism in the air cooler.Computational fluid dynamics(CFD)was used to calculate the hydrodynamic parameters of the air cooler.The results showed that there was a biased flow in the air cooler,which led to a significant increase in velocity,turbulent kinetic energy and wall shear within 0.2 m of the tube entrance.A visualization experiment was then performed to determine the principles of migration and transformation of multiphase flow in the air cooler tubes.Various flow patterns(pure droplet flow,mist flow,and annular flow)and their evolutionary processes were clearly depicted experimentally.The initiation mechanism and processes leading to the development of E-C in the air cooler were also determined.This study provided a comprehensive explanation for the E-C failures that occur in air coolers during operation. 展开更多
关键词 air cooler hydrocracking unit EROSION-CORROSION SIMULATION visualization experiment multiphase flow
下载PDF
The Regulatory Role and Mechanism of Circadian Rhythm in Hemoglobin Co-cultured Neurovascular Unit
11
作者 Fang Xue Wenchao Chen +4 位作者 Xia Lian Guanghui He Jingyuan Tian Yinghong Liu Gaiqing Wang 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2024年第7期726-738,共13页
Objective Intracranial hemorrhage(ICH),the second most common subtype of stroke,exacerbates the disruption of the blood-brain barrier(BBB),leading to vasogenic edema,plasma protein extravasation,and infiltration of ne... Objective Intracranial hemorrhage(ICH),the second most common subtype of stroke,exacerbates the disruption of the blood-brain barrier(BBB),leading to vasogenic edema,plasma protein extravasation,and infiltration of neurotoxic substances.The clearance capacity of the brain plays a crucial role in maintaining BBB homeostasis and facilitating patient recovery after hemorrhage.This study aimed to investigate the effect of circadian rhythms on BBB function,neuronal damage,and clearance capabilities.Methods The transwell model and hemoglobin were co-cultured to simulate the BBB environment after ICH.After intervention with different light groups,neuronal apoptosis was determined,glial phagocytosis was analyzed,the expression of endogenous clearing-related proteins aquaporin 4(AQP4)and low-density lipoprotein receptor-related protein 1(LRP1)was detected by western blotting and immunofluorescence dual standard method,and the expression of the tight junction protein occludin and melatonin receptor 1A(MTNR1A)was quantitatively analyzed.Results Circadian rhythms play a key role in maintaining the integrity of the BBB,reducing oxidative stress-induced neuronal damage,and improving microglial phagocytosis.Meanwhile,the expression of occludin and MTNR1A in neurovascular unit(NVU)co-cultured with hemoglobin improved the expression of AQP4 and LRP1,the key proteins in the NVU's endogenous brain clearance system.Conclusion Circadian rhythm(alternating black and white light)protects the NVU BBB function after ICH,promotes the expression of proteins related to the clearance of the hematoma,provides new evidence for the clinical treatment of patients recovering from ICH,and improves the circadian rhythm to promote brain metabolism and hematoma clearance. 展开更多
关键词 Blood-brain barrier Circadian rhythm Neurovascular unit Melatonin receptor 1A AQUAPORIN-4
下载PDF
Maternal Mortality Rates among Im/Migrant Populations in the United States
12
作者 Tessa Peredy Mary Greenwald +4 位作者 Katy Doughty Fachon Fiona Danaher Rashmi Jasrasaria Samantha Truong Annekathryn Goodman 《Open Journal of Obstetrics and Gynecology》 2024年第8期1161-1175,共15页
Introduction: Maternal mortality rates have more than doubled in the U.S over the last two decades, making it one of the few places in the world where maternal mortality is increasing. Differences in maternal mortalit... Introduction: Maternal mortality rates have more than doubled in the U.S over the last two decades, making it one of the few places in the world where maternal mortality is increasing. Differences in maternal mortality among certain races and ethnicities are known but few studies examine maternal mortality among immigrants. Since immigrants represent 13.7% of the U.S. population, it is essential to examine immigrant subsets to understand maternal mortality among this vulnerable population. Methods: A literature search identified 318 articles on maternal mortality and immigrants, with 12 articles from the U.S. The keywords included maternal mortality, United States, migrants, asylum seekers, immigrants, and disparities. Maternal mortality statistics were obtained from the World Health Organization and Center for Disease Control. Results: Studies analyzed in this review found an overall lower maternal mortality rate among immigrant women compared to U.S.-born women, except for Hispanic immigrant women. Black women had the highest maternal mortality rate, regardless of immigration status. Conclusion: Although the literature points to lower maternal mortality among immigrants, the data is still somewhat mixed, making it challenging to draw comprehensive conclusions. Additional research examining maternal mortality among Im/migrants in the U.S. is needed to guide future training among healthcare professionals and policymakers. 展开更多
关键词 Maternal Mortality Im/Migrant Reproductive Health united States
下载PDF
The Enforcement of Occupational Safety and Health Requirements in Public and Private Sectors in the Emirate of Abu Dhabi, the United Arab Emirates
13
作者 Alyazya Alhosani 《Occupational Diseases and Environmental Medicine》 2024年第2期78-114,共37页
Research Problem: In Abu Dhabi, limited implementation of OSH Regulations contributes to the general unawareness among employees and workers about occupational hazards and safety measures, resulting in slow responsive... Research Problem: In Abu Dhabi, limited implementation of OSH Regulations contributes to the general unawareness among employees and workers about occupational hazards and safety measures, resulting in slow responsiveness toward enforcement measures and a lack of self-regulatory approaches within companies. Purpose: The purpose of this study is to examine the implementation methods practised in Abu Dhabi with those in developed countries with established OSH regulatory bodies. Methodology: Qualitative and quantitative research methods were employed to gather primary research data. Workers from various industries in Abu Dhabi were sampled on purpose and asked to respond to questionnaires and interviews on OSH protocol awareness and implementation, and circumstances of workplace incidence. Results: The findings of this study showed that the enforcement of OSH requirements in UAE positively correlated to a reduction in the rate of work-related injury and improved business performance. The quantitative research data showed that the energy sector had the highest score (15) while the tourism sector had the lowest score (5.3) in occupational health systems and improvements in business efficiency and productivity. Implications: The outcomes of this study shed light on the importance of implementing OSH Guidelines for companies to empower their safety managers to fully enforce OSH requirements in their organisations. In conclusion, effective OSH enforcement requires cooperation between general workers and OSH managers and facilitation from business owners. 展开更多
关键词 Occupational Health and Safety Abu Dhabi The united Arab Emirates IMPLEMENTATION
下载PDF
Hounsfield units in assessing bone mineral density in ankylosing spondylitis patients with cervical fracture-dislocation
14
作者 Zhong-Ya Gao Wei-Lin Peng +1 位作者 Yang Li Xu-Hua Lu 《World Journal of Clinical Cases》 SCIE 2024年第23期5329-5337,共9页
BACKGROUND Cervical spine fracture-dislocations in patients with ankylosing spondylitis(AS)are mostly unstable and require surgery.However,osteoporosis,one of the comorbidities for AS,could lead to detrimental prognos... BACKGROUND Cervical spine fracture-dislocations in patients with ankylosing spondylitis(AS)are mostly unstable and require surgery.However,osteoporosis,one of the comorbidities for AS,could lead to detrimental prognoses.There are few accurate assessments of bone mineral density in AS patients.AIM To analyze Hounsfield units(HUs)for assessing bone mineral density in AS patients with cervical fracture-dislocation.METHODS The HUs from C2 to C7 of 51 patients obtained from computed tomography(CT)scans and three-dimensional reconstruction of the cervical spine were independently assessed by two trained spinal surgeons and statistically analyzed.Inter-reader reliability and agreement were assessed by interclass correlation coefficient.RESULTS The HUs decreased gradually from C2 to C7.The mean values of the left and right levels were significantly higher than those in the middle.Among the 51 patients,25 patients(49.02%)may be diagnosed with osteoporosis,and 16 patients(31.37%)may be diagnosed with osteopenia.CONCLUSION The HUs obtained by cervical spine CT are feasible for assessing bone mineral density with excellent agreement in AS patients with cervical fracture-dislocation. 展开更多
关键词 Hounsfield unit Ankylosing spondylitis FRACTURE-DISLOCATION Cervical spine OSTEOPOROSIS
下载PDF
Hydrodynamic Assessment of A New Nature-Based Armour Unit on Rubble Mound Breakwater for Coastal Protection
15
作者 Ehsan SAFA Alireza MOJTAHEDI +1 位作者 Abdolmajid MOHAMMADIAN Mohamad Ali Lotfollahi YAGHIN 《China Ocean Engineering》 SCIE EI CSCD 2024年第3期439-452,共14页
This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details... This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details, and porosity.Therefore, a detailed analysis is required to investigate the exact state of their hydraulic interactions and structuralresponses. In this regard, the performance results of several traditional armour units, including the Antifer cube,Tetrapod, X-block and natural stone, are considered for the first step of this study. Then, the related observed resultsare compared with those obtained for a newly designed (artificial coral) armour unit. The research methodology utilizesthe common wave flume test procedure. Furthermore, several verified numerical models in OpenFOAM code areused to gain the extra required data. The proposed armour is configured to provide an effective shore protection as anenvironmental-friendly coastal structure. Thus it is designed with a main trunk including deep grooves to imitate thetypical geometry of a coral type configuration, so as to attain desirable performance. The observed results and ananalytic hierarchy process (AHP) concept are used to compare the hydraulic performance of the studied traditionaland newly proposed (artificial coral) armour units. The results indicate that the artificial coral armour unit demonstratesacceptable performance. The widely used traditional armour units might be replaced by newer designs for betterwave energy dissipation, and more importantly, for fewer adverse effects on the marine environment. 展开更多
关键词 rubble mound breakwater hydraulic interaction armour unit analytic hierarchy process numerical model
下载PDF
Bionic lightweight design of limb leg units for hydraulic quadruped robots by additive manufacturing and topology optimization
16
作者 Huaizhi Zong Junhui Zhang +6 位作者 Lei Jiang Kun Zhang Jun Shen Zhenyu Lu Ke Wang Yanli Wang Bing Xu 《Bio-Design and Manufacturing》 SCIE EI CAS CSCD 2024年第1期1-13,共13页
Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadr... Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency. 展开更多
关键词 Additive manufacturing Bionic lightweight design Limb leg unit Quadruped robot Trajectory tracking
下载PDF
Travel-Limiting Disabilities in the United States: Why Accessibility Matters?
17
作者 Oluwaseun Ibukun Bhuiyan Alam 《Journal of Transportation Technologies》 2024年第3期336-357,共22页
This study evaluates the distribution of travel-limiting disabilities across genders and geographic locations in the United States. This study aims to describe and compare the socioeconomic and demographic variables o... This study evaluates the distribution of travel-limiting disabilities across genders and geographic locations in the United States. This study aims to describe and compare the socioeconomic and demographic variables of the people with and without travel-limiting disabilities across geographic locations and gender. The study further evaluates the trip purpose and impact of Covid-19 fourth wave pandemic on the use of public transit and travel to physical workplace for the people with and without travel-limiting disabilities across gender and geographic locations. The study uses the 2022 weighted National Household Travel Survey dataset and employs descriptive statistics. Results reaffirm the findings from previous literature that there are more people with travel-limiting disabilities in urban areas and among women. Over 50 percent of people aged 65 and above have a form of travel-limiting disabilities. The most trip for people with travel-limiting disabilities is made for shopping and medical purposes. Across all categories, rural areas, urban areas, male and female for the people without travel-limiting disabilities, COVID-19 fourth wave did not change the pattern of trips made to physical workplace as pre-COVID-19 era. This pattern is also observable for the people with travel-limiting disabilities in rural and urban areas. Females with travel-limiting disabilities reported making less trips to physical workplaces while male reported doing the same as before COVID-19 era. The study concludes that the quantification of travel-limiting disabilities across geographic location and gender is vital in disability study and could drive policy implementation for improved accessibility for the vulnerable population. 展开更多
关键词 National Household Travel Survey united States Travel-Limiting Disabilities Descriptive Statistics Covid-19 Disability Study
下载PDF
Risk factors for intensive-care-unit-acquired weakness
18
作者 Ming Liu Yu-Tong Chen +1 位作者 Guang-Liang Wang Xue-Mei Wu 《World Journal of Clinical Cases》 SCIE 2024年第21期4853-4855,共3页
Wang et al reported 1063 cases from the initial 14 d of intensive care unit(ICU)stay,and analyzed relevant data such as age,comorbidities,recent dosages,vapor pressure dosages,duration of mechanical ventilation,length... Wang et al reported 1063 cases from the initial 14 d of intensive care unit(ICU)stay,and analyzed relevant data such as age,comorbidities,recent dosages,vapor pressure dosages,duration of mechanical ventilation,length of ICU stay,and rehabilitation therapy,which are closely related to ICU-acquired weakness(ICUAW).It is suggested that the length of ICU stay and the duration of mechanical ventilation are the main factors.ICU-AW is the most common neuromuscular injury in the ICU,which affects clinical progression and outcomes of patients.This manuscript helps to improve the early recognition of ICU-AW,thereby reducing mortality and improving prognosis. 展开更多
关键词 Risk factors Intensive care unit Acquired weakness Prognosis Neuromuscular injury
下载PDF
Improved Unit Commitment with Accurate Dynamic Scenarios Clustering Based on Multi-Parametric Programming and Benders Decomposition
19
作者 Zhang Zhi Haiyu Huang +6 位作者 Wei Xiong Yijia Zhou Mingyu Yan Shaolian Xia Baofeng Jiang Renbin Su Xichen Tian 《Energy Engineering》 EI 2024年第6期1557-1576,共20页
Stochastic unit commitment is one of the most powerful methods to address uncertainty. However, the existingscenario clustering technique for stochastic unit commitment cannot accurately select representative scenario... Stochastic unit commitment is one of the most powerful methods to address uncertainty. However, the existingscenario clustering technique for stochastic unit commitment cannot accurately select representative scenarios,which threatens the robustness of stochastic unit commitment and hinders its application. This paper providesa stochastic unit commitment with dynamic scenario clustering based on multi-parametric programming andBenders decomposition. The stochastic unit commitment is solved via the Benders decomposition, which decouplesthe primal problem into the master problem and two types of subproblems. In the master problem, the committedgenerator is determined, while the feasibility and optimality of generator output are checked in these twosubproblems. Scenarios are dynamically clustered during the subproblem solution process through the multiparametric programming with respect to the solution of the master problem. In other words, multiple scenariosare clustered into several representative scenarios after the subproblem is solved, and the Benders cut obtainedby the representative scenario is generated for the master problem. Different from the conventional stochasticunit commitment, the proposed approach integrates scenario clustering into the Benders decomposition solutionprocess. Such a clustering approach could accurately cluster representative scenarios that have impacts on theunit commitment. The proposed method is tested on a 6-bus system and the modified IEEE 118-bus system.Numerical results illustrate the effectiveness of the proposed method in clustering scenarios. Compared withthe conventional clustering method, the proposed method can accurately select representative scenarios whilemitigating computational burden, thus guaranteeing the robustness of unit commitment. 展开更多
关键词 Stochastic programming unit commitment scenarios clustering Benders decomposition multi-parametric programming
下载PDF
Petrogenesis and Tectonic Implications of the Early Triassic Nianzi Adakitic Granite Unit in the Yanshan Fold and Thrust Belt:New Constraints from U-Pb Geochronology and Sr-Nd-Hf Isotopes
20
作者 ZHANG Huijun WU Chu +5 位作者 HE Fubing WANG Biren CUI Yubin LIU Zhenghua YOU Shina DONG Jing 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2024年第1期50-66,共17页
The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thru... The Nianzi granite unit,which includes the Nianzi,Xiaolianghou and Xiawopu granitic intrusions,is a significant component of the northern part of the North China Craton(NCC)and is situated in the Yanshan fold and thrust belt(YFTB).However,there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period,specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean.The Nianzi granite unit exhibits unique petrological,geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB.This study presents detailed petrology,whole-rock geochemistry,together with Sr-Nd isotopic,zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit.Our findings demonstrate that the granites primarily consist of subhedral K-feldspar,plagioclase,quartz,minor biotite and hornblende,with accessory titanite,apatite,magnetite and zircon.Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5±0.62 Ma.Additionally,the adakitic characteristics of the Nianzi,Xiawopu and Xiaolianghou granitic intrusions,such as high Sr and Ba contents and high ratios of Sr/Y and(La/Yb)N,combined with negative Sr-Nd and Lu-Hf isotopes(87Sr/86Sr)i=0.705681–0.7057433,εNd(t)=−21.98 to−20.97,zirconεHf(t)=−20.26 to−9.92,as well as the I-type granite features of high SiO_(2),Na_(2)O and K_(2)O/Na_(2)O ratios,enriched Rb,K,Sr and Ba,along with depleted Th,U,Nb,Ta,P and Ti,suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous,calc-alkaline to high-K calc-alkaline,mafic to intermediate metamorphic rocks.In light of these parameters,we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic. 展开更多
关键词 tectonic evolution zircon geochronology Sr-Nd-Hf isotopes Nianzi granite unit Yanshan fold and thrust belt
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部