期刊文献+
共找到5,162篇文章
< 1 2 250 >
每页显示 20 50 100
Analysis of rotor eddy current loss and thermal deformation of magnetic liquid double suspension bearing
1
作者 LIU Hongmei YANG Guang +3 位作者 SUN Yanan SUN Jian WANG Zhe ZHAO Jianhua 《High Technology Letters》 EI CAS 2024年第3期322-332,共11页
Magnetic-liquid double suspension bearing(MLDSB)is a new type of suspension bearing based on electromagnetic suspension and supplemented by hydrostatic supporting.Without affecting the electromagnetic suspension force... Magnetic-liquid double suspension bearing(MLDSB)is a new type of suspension bearing based on electromagnetic suspension and supplemented by hydrostatic supporting.Without affecting the electromagnetic suspension force,the hydrostatic supporting effect is increased,and the real-time coupling of magnetic and liquid supporting can be realized.However,due to the high rotation speed,the rotor part produces eddy current loss,resulting in a large temperature rise and large ther-mal deformation,which makes the oil film thickness deviate from the initial design.The support and bearing characteristics are seriously affected.Therefore,this paper intends to explore the internal effects of eddy current loss of the rotor on the temperature rise and thermal deformation of MLDSB.Firstly,the 2D magnetic flow coupling mathematical model of MLDSB is established,and the eddy current loss distribution characteristics of the rotor are numerically simulated by Maxwell software.Secondly,the internal influence of mapping relationship of structural operating parameters such as input current,coil turns and rotor speed on rotor eddy current loss is revealed,and the changing trend of rotor eddy current loss under different design parameters is explored.Thirdly,the eddy cur-rent loss is loaded into the heat transfer finite element calculation model as a heat source,and the temperature rise of the rotor and its thermal deformation are simulated and analyzed,and the influ-ence of eddy current loss on rotor temperature rise and thermal deformation is revealed.Finally,the pressure-flow curve and the distribution law of the internal flow field are tested by the particle image velocimetry(PIV)system.The results show that eddy current loss increases linearly with the in-crease of coil current,coil turns and rotor speed.The effect of rotational speed on eddy current loss is much higher than that of coil current and coil turns.The maximum temperature rise,minimum temperature rise and maximum thermal deformation of the rotor increase with the increase of eddy current loss.The test results of flow-pressure and internal trace curves are basically consistent with the theoretical simulation,which effectively verifies the correctness of the theoretical simulation.The research results can provide theoretical basis for the design and safe and stable operation of magnetic fluid double suspension bearings. 展开更多
关键词 magnetic-liquid double suspension bearing(MLDSB) oil film thickness cur-rent loss thermal deformation particle image velocimetry(PIV)test
下载PDF
Influence of layer thickness on formation quality,microstructure,mechanical properties,and corrosion resistance of WE43 magnesium alloy fabricated by laser powder bed fusion 被引量:2
2
作者 Bangzhao Yin Jinge Liu +7 位作者 Bo Peng Mengran Zhou Bingchuan Liu Xiaolin Ma Caimei Wang Peng Wen Yun Tian Yufeng Zheng 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第4期1367-1385,共19页
Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical parts.Layer thickness(LT)is of great significance to the L-PBF process but has not... Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical parts.Layer thickness(LT)is of great significance to the L-PBF process but has not been studied for Mg alloys.In this study,WE43 Mg alloy bulk cubes,porous scaffolds,and thin walls with layer thicknesses of 10,20,30,and 40μm were fabricated.The required laser energy input increased with increasing layer thickness and was different for the bulk cubes and porous scaffolds.Porosity tended to occur at the connection joints in porous scaffolds for LT40 and could be eliminated by reducing the laser energy input.For thin wall parts,a large overhang angle or a small wall thickness resulted in porosity when a large layer thicknesses was used,and the porosity disappeared by reducing the layer thickness or laser energy input.A deeper keyhole penetration was found in all occasions with porosity,explaining the influence of layer thickness,geometrical structure,and laser energy input on the porosity.All the samples achieved a high fusion quality with a relative density of over 99.5%using the optimized laser energy input.The increased layer thickness resulted to more precipitation phases,finer grain sizes and decreased grain texture.With the similar high fusion quality,the tensile strength and elongation of bulk samples were significantly improved from 257 MPa and 1.41%with the 10μm layer to 287 MPa and 15.12%with the 40μm layer,in accordance with the microstructural change.The effect of layer thickness on the compressive properties of porous scaffolds was limited.However,the corrosion rate of bulk samples accelerated with increasing the layer thickness,mainly attributed to the increased number of precipitation phases. 展开更多
关键词 Magnesium alloy WE43 Laser powder bed fusion layer thickness Process optimization
下载PDF
Variation in the permafrost active layer over the Tibetan Plateau during 1980–2020 被引量:1
3
作者 Jinglong Huang Chaofan Li +2 位作者 Binghao Jia Chujie Gao Ruichao Li 《Atmospheric and Oceanic Science Letters》 CSCD 2024年第5期34-39,共6页
The active layer,acting as an intermediary of water and heat exchange between permafrost and atmosphere,greatly influences biogeochemical cycles in permafrost areas and is notably sensitive to climate fluctuations.Uti... The active layer,acting as an intermediary of water and heat exchange between permafrost and atmosphere,greatly influences biogeochemical cycles in permafrost areas and is notably sensitive to climate fluctuations.Utilizing the Chinese Meteorological Forcing Dataset to drive the Community Land Model,version 5.0,this study simulates the spatial and temporal characteristics of active layer thickness(ALT)on the Tibetan Plateau(TP)from 1980 to 2020.Results show that the ALT,primarily observed in the central and western parts of the TP where there are insufficient station observations,exhibits significant interdecadal changes after 2000.The average thickness on the TP decreases from 2.54 m during 1980–1999 to 2.28 m during 2000–2020.This change is mainly observed in the western permafrost region,displaying a sharp regional inconsistency compared to the eastern region.A persistent increasing trend of ALT is found in the eastern permafrost region,rather than an interdecadal change.The aforementioned changes in ALT are closely tied to the variations in the surrounding atmospheric environment,particularly air temperature.Additionally,the area of the active layer on the TP displays a profound interdecadal change around 2000,arising from the permafrost thawing and forming.It consistently decreases before 2000 but barely changes after 2000.The regional variation in the permafrost active layer over the TP revealed in this study indicates a complex response of the contemporary climate under global warming. 展开更多
关键词 Active layer thickness PERMAFROST Tibetan plateau Climatological characteristics
下载PDF
Structure characterization of the oxide film on FGH96 superalloy powders with various oxidation degrees
4
作者 Yang Liu Yufeng Liu +6 位作者 Sha Zhang Lin Zhang Peng Zhang Shaorong Zhang Na Liu Zhou Li Xuanhui Qu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第9期2037-2047,共11页
The structure of the oxide film on FGH96 alloy powders significantly influences the mechanical properties of superalloys.In this study,FGH96 alloy powders with various oxygen contents were investigated using high-reso... The structure of the oxide film on FGH96 alloy powders significantly influences the mechanical properties of superalloys.In this study,FGH96 alloy powders with various oxygen contents were investigated using high-resolution transmission electron microscopy and atomic probe technology to elucidate the structure evolution of the oxide film.Energy dispersive spectrometer analysis revealed the presence of two distinct components in the oxide film of the alloy powders:amorphous oxide layer covering the γ matrix and amorphous oxide particles above the carbide.The alloying elements within the oxide layer showed a laminated distribution,with Ni,Co,Cr,and Al/Ti,which was attributed to the decreasing oxygen equilibrium pressure as oxygen diffused from the surface into the γ matrix.On the other hand,Ti enrichment was observed in the oxide particles caused by the oxidation and decomposition of the carbide phase.Comparative analysis of the oxide film with oxygen contents of 140,280,and 340 ppm showed similar element distributions,while the thickness of the oxide film varies approximately at 9,14,and 30 nm,respectively.These findings provide valuable insights into the structural analysis of the oxide film on FGH96 alloy powders. 展开更多
关键词 Ni-based superalloys surface structure oxide layer thickness oxidation behavior element distribution
下载PDF
Early diagnostic value of carotid artery ultrasound parameters combined with epicardial adipose layer thickness in coronary heart disease
5
作者 Min Xu Zhao-Yang Lu 《World Journal of Clinical Cases》 SCIE 2024年第17期3004-3011,共8页
BACKGROUND Coronary heart disease is associated with coronary atherosclerosis indicated by carotid intima-media thickness(CIMT)thickening and altered vascular elasticity.The epicardial adipose layer can secrete proinf... BACKGROUND Coronary heart disease is associated with coronary atherosclerosis indicated by carotid intima-media thickness(CIMT)thickening and altered vascular elasticity.The epicardial adipose layer can secrete proinflammatory factors that promote the formation of coronary atherosclerosis.Thus,the epicardial fat layer thickness(EAT)may also predict coronary heart disease.AIM To determine the role of common carotid artery ultrasound parameters and EAT in the early diagnosis of coronary artery disease.METHODS Based on coronary angiography,patients with newly suspected coronary heart disease were divided into case(n=107)and control(n=41)groups.The carotid ultrasound parameters,including vascular stiffness(β),elastic coefficient(EP),pulse wave conduction velocity(PWV-β),CIMT,and EAT were compared between the case and control groups and among patients with different lesion numbers in the case group.Pearson correlation was used to evaluate the early diagnostic value of EAT,common carotid artery elasticity,and CIMT for coronary heart disease.RESULTS EP,β,PWV-β,CIMT,and EAT were significantly higher in the case group compared with the levels in the control group(all P<0.001).In the case group,lesions were detected in one vessel in 34 patients,two vessels in 38 patients,and three vessels in 35 patients.Within the case group,β,EP,PWV-β,CIMT,and EAT levels significantly increased with an increased number of lesions(all P<0.001).EAT positively correlated withβ,EP,PWV-β,and CIMT(all P<0.01).The area under the curve for diagnosing coronary heart disease using EAT combined with CIMT and carotid elasticity was 0.893,and the sensitivity and specificity were 0.890 and 0.837.CONCLUSION EAT correlated well with changes in carotid artery elasticity and CIMT in patients with coronary heart disease.The combination of EAT,carotid artery elasticity,and CIMT facilitates the early diagnosis of coronary heart disease. 展开更多
关键词 Carotid artery ULTRASOUND Epicardial adipose layer thickness Coronary heart disease Early diagnosis
下载PDF
Ice thickness,internal layers,and surface and subglacial topography in the vicinity of Chinese Antarctic Taishan station in Princess Elizabeth Land,East Antarctica 被引量:1
6
作者 唐学远 郭井学 +2 位作者 孙波 王甜甜 崔祥斌 《Applied Geophysics》 SCIE CSCD 2016年第1期203-208,222,223,共8页
We present the results of two ground-based radio-echo-sounding(RES) and GPS surveys performed in the vicinity of new Chinese Taishan station,Princess Elizabeth Land,East Antarctica,obtained in two austral summers du... We present the results of two ground-based radio-echo-sounding(RES) and GPS surveys performed in the vicinity of new Chinese Taishan station,Princess Elizabeth Land,East Antarctica,obtained in two austral summers during CHINARE 21(2004/2005) and CHINARE 29(2012/2013).The radar surveys measured ice thickness and internal layers using 60- and 150-MHz radar systems,and GPS measurements showed smooth surface slopes around the station with altitudes of 2607-2636 m above sea level(a.s.l.).Radar profiles indicate an average ice thickness of 1900 m,with a maximum of 1949 m and a minimum of 1856 m,within a square area measuring approximately 2 km × 2 km in the vicinity of the station.The ice thickness beneath the station site is 1870 m.The subglacial landscape beneath the station is quiet sharp and ranges from 662 to 770 m a.s.l.,revealing part of a mountainous topography.The ice volume in the grid is estimated to be 7.6 km^3.Along a 60-MHz radar profile with a length of 17.6 km at the region covering the station site,some disturbed internal layers are identified and traced;the geometry of internal layers within the englacial stratigraphy may imply a complex depositional process in the area. 展开更多
关键词 East Antarctica Taishan station ice thickness internal layers ground-based radio echo sounding
下载PDF
Lipid layer thickness and tear meniscus height measurements for the differential diagnosis of evaporative dry eye subtypes 被引量:9
7
作者 Xuan Sang Yan Li +8 位作者 Liu Yang Jia-Hui Liu Xiao-Ran Wang Chao-Yang Li Ying Liu Chen-Jie Wang Xiong-Jun He Shou-Bi Wang Zhi-Chong Wang 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2018年第9期1496-1502,共7页
AIM: To explore a new diagnostic index for differentiating the evaporative dry eye(EDE) subtypes by analysis of their respective clinical characteristics. METHODS: A cross-sectional study of 139 patients(139 eyes... AIM: To explore a new diagnostic index for differentiating the evaporative dry eye(EDE) subtypes by analysis of their respective clinical characteristics. METHODS: A cross-sectional study of 139 patients(139 eyes) with EDE who were enrolled and classified as obstructive meibomian gland dysfunction(MGD)(n=81) and non-obstructive MGD(n=58) EDE. All patients completed a Standard Patient Evaluation of Eye Dryness(SPEED) questionnaire and were evaluated for average lipid layer thickness(LLT), tear meniscus height measurements(TMH), tear break-up time(TBUT), ocular surface staining score, Schirmer I test(SIT), lid margin abnormalities, and meibomian gland function and morphology. RESULTS: Age, average LLT, TMH, scores of lid margin abnormalities, meibum quality, meibomian gland loss(MGL)(all P≤0.001), and TBUT(P=0.03) were all significantly different between obstructive MGD EDE patients and nonobstructive MGD EDE patients. Average LLT in obstructive MGD EDE was correlated with meibomian expressibility(r=-0.541, P≤0.001), lid margin abnormalities were marginally not significant(r=0.197, P=0.077), and TMH was correlated with MGL(total MGL: r=0.552, P≤0.001; upper MGL: r=0.438, P≤0.001; lower MGL: r=0.407, P≤0.001). Average LLT in non-obstructive MGD EDE, was correlated with meibomian expressibility and Oxford staining(r=-0.396, P=0.002; r=-0.461, P≤0.001). The efficiency of combining average LLT and TMH was optimal, with a sensitivity of 80.2% and a specificity of 74.1%. Obstructive MGD EDE patients had an average LLT≥69 nm and TMH≥0.25 mm, while non-obstructive MGD EDE patients had an average LLT〈69 nm and TMH〈0.25 mm.CONCLUSION: Obstructive MGD EDE and nonobstructive MGD EDE have significantly different clinical characteristics. Combining average LLT and TMH measurements enhanced their reliability for differentiating these two subtypes and provided guidance for offering more precise treatments for EDE subtypes. 展开更多
关键词 evaporative dry eye lipid layer thickness tear meniscus height
下载PDF
Low concentration of sodium hyaluronate temporarily elevates the tear film lipid layer thickness in dry eye patients with lipid deficiency 被引量:6
8
作者 Yan Li Xuan Sang +6 位作者 Liu Yang Xiao-Ran Wang Jia-Hui Liu Xiong-Jun He Ying Liu Xiao-He Lu Zhi-Chong Wang 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2018年第3期389-394,共6页
AIM: To investigate the effects of different concentrations of artificial tears on lipid layer thickness (LLT) and blink rate (BR) in dry eye patients. METHODS: This study included 106 eyes of 58 patients with ... AIM: To investigate the effects of different concentrations of artificial tears on lipid layer thickness (LLT) and blink rate (BR) in dry eye patients. METHODS: This study included 106 eyes of 58 patients with dry eye. The lipid deficiency type was defined as the LLT baseline 〈75 nm. The LLT and BR were measured at baseline and 1, 5 and 15min after the instillation of 0.1% or 0.3% sodium hyaluronate (SH) eye drops by using the LipiView ocular surface interferometer. RESULTS: In the lipid deficiency group, the LLT increased from baseline at 1rain post instillation. The LLT after the instillation of 0.1% SH was significantly higher than that after the instillation of 0.3% SH (P〈0.001). The LLT returned to baseline at 15min post instillation of 0.1% SH and at 5min post instillation of 0.3% SH. In the non-lipid deficiency group, the LLT decreased from baseline at lmin and returned to baseline at 5rain for both treatments. The BRs were not significantly different at different time points for both treatments. CONCLUSION: SH eye drops induce a short-term increase in LLT of patients with lipid deficiency. A low concentration of artificial tears have a stronger effect than a high concentration of artificial tears on the increase in LLT. in comparison, SH eye drops induce a transient and slight decrease in LLT of patients without lipid deficiency. A low concentration of artificial tears might be better for patients with lipid deficiency. 展开更多
关键词 tear film lipid layer thickness dry eye artificialtears ocular surface interferometer sodium hyaluronate
下载PDF
THE APPLICATION OF ARTIFICIAL NEURAL NETWORKS TO INVESTIGATION ON THE THICKNESS OF INTERMETALLIC LAYER UNDER SOLID-LIQUID PRESSURE BONDING OF STEEL AND ALUMINIUM 被引量:8
9
作者 P. Zhang J.Z. Cui Y.H. Du and Q.Z. Zhang(Department of Metal Forming, Northeastern University, Shenyang 110006, China)(Department of Mining, Northeastern University, Shenyang 110006, China) 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1997年第6期523-526,共4页
Artificial neural networks (ANN), being a sophisticated type of information processing system by imitating the neural system of human brain, can be used to investigate the effects of concentration of flux solution, te... Artificial neural networks (ANN), being a sophisticated type of information processing system by imitating the neural system of human brain, can be used to investigate the effects of concentration of flux solution, temperature of liquid aluminium, temperture of tools and pressure on thickness of the intermetallic layer at the interface between steel and aluminium under solid-liquid pressure bonding of steel and aluminium perfectly. The optimum thickness has been determined according to the value of the optimum shearing strength. 展开更多
关键词 artificial neural network thickness of the intermetallic layer solid-liquid pressure bonding
下载PDF
Effects of ultraviolet(UV) radiation and litter layer thickness on litter decomposition of two tree species in a semi-arid site of Northeast China 被引量:3
10
作者 MAO Bing ZHAO Lei +1 位作者 ZHAO Qiong ZENG Dehui 《Journal of Arid Land》 SCIE CSCD 2018年第3期416-428,共13页
Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet(UV) radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. H... Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet(UV) radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar(Populus × xiaozhuanica) and Mongolian pine(Pinus sylvestris var. mongolica) plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations. 展开更多
关键词 LIGNIN litter decomposition litter layer thickness nitrogen forest plantation PHOTODEGRADATION UV radiation
下载PDF
Fine-tuning the thicknesses of organic layers to realize high-efficiency and long-lifetime blue organic light-emitting diodes 被引量:1
11
作者 于建宁 张民艳 +4 位作者 李崇 尚玉柱 吕燕芳 魏斌 黄维 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第8期186-190,共5页
By using p-bis(p - N, N-diphenyl-aminostyryl)benzene doped 2-tert-butyl-9, 10-bis-β-naphthyl)-anthracene as an emitting layer, we fabricate a high-efficiency and long-lifetime blue organic light emitting diode wit... By using p-bis(p - N, N-diphenyl-aminostyryl)benzene doped 2-tert-butyl-9, 10-bis-β-naphthyl)-anthracene as an emitting layer, we fabricate a high-efficiency and long-lifetime blue organic light emitting diode with a maximum external quantum efficiency of 6.19% and a stable lifetime at a high initial current density of 0.0375 A/cm2. We demonstrate that the change in the thicknesses of organic layers affects the operating voltage and luminous efficiency greater than the lifetime. The lifetime being independent of thickness is beneficial in achieving high-quality full-colour display devices and white lighting sources with multi-emitters. 展开更多
关键词 organic light-emitting diode blue emission LIFETIME organic layers thickness
下载PDF
Forming mechanism of ink layer on the printing plate in inking process and influencing factors of its thickness
12
作者 初红艳 Xu Kangjian +1 位作者 Zhang Xiaolin Cai Ligang 《High Technology Letters》 EI CAS 2016年第3期297-304,共8页
Ink layer thickness on the printing plate greatly influences uniformity of ink transferred to the substrates,which is an important indicator of printing quality,so the study of ink layer and its thickness is important... Ink layer thickness on the printing plate greatly influences uniformity of ink transferred to the substrates,which is an important indicator of printing quality,so the study of ink layer and its thickness is important for improving the quality of printing products. Ansys CFX is used here to build a model of ink fluid adhering to lower vibrator roller,form inking roller,and printing plate for analyzing ink transferring in inking process. Ink layer thickness on each position of the model is acquired to analyze the forming mechanism of ink layer on printing plate,as well as the influence of oscillation speed of lower vibrator roller and dot area percentage of plate on ink layer thickness of printing plate. It can be concluded that,in the case of fixed ink supplying amount,ink layer thickness increases along with the increasing of oscillation speed,and decreases when the dot area percentage is getting larger and the minimum is got when the dot area percentage is 100%. At last,experiment of plate inking on print ability tester verifies the correctness of the simulation analysis. 展开更多
关键词 PRINTING OSCILLATION dot area percentage ink layer thickness
下载PDF
Effects of Layer Thickness and Edge Conditions to Thermoelastic Characteristics on Thermal Barrier Coatings
13
作者 Jaegwi Go Je-Hyun Lee 《Applied Mathematics》 2014年第16期2417-2425,共9页
The thermoelastic behaviors of such as temperature distribution, displacements, and stresses in thermal barrier coatings (TBC) are seriously influenced by top coat thickness and edge conditions. The top coat of TBC sp... The thermoelastic behaviors of such as temperature distribution, displacements, and stresses in thermal barrier coatings (TBC) are seriously influenced by top coat thickness and edge conditions. The top coat of TBC specimens prepared with TriplexPro?-200 system was controlled by changing the processing parameter and feedstock, showing the various thicknesses and microstructures. A couple of governing partial differential equations were derived based on the thermoelastic theory. Since the governing equations were too involved to solve analytically, a finite volume method was developed to obtain approximations. The thermoelastic behaviors of TBC specimens with the various thicknesses and microstructures were estimated through mathematical approaches with different edge conditions. The results demonstrated that the microstructure and thickness of the top coat, and the edge condition in theoretical analysis were crucial factors to be considered in controlling the thermoelastic characteristics of plasma-sprayed TBCs. 展开更多
关键词 thermal BARRIER Coatings Air Plasma SPRAY layer thickness theRMOELASTIC CHARACTERISTICS FINITE Volume Method
下载PDF
Simulated response of the active layer thickness of permafrost to climate change
14
作者 Ruichao Li Jinbo Xie +7 位作者 Zhenghui Xie Junqiang Gao Binghao Jia Peihua Qin Longhuan Wang Yan Wang Bin Liu Si Chen 《Atmospheric and Oceanic Science Letters》 CSCD 2021年第1期40-45,共6页
The active layer thickness(ALT)in permafrost regions,which affects water and energy exchange,is a key variable for assessing hydrological processes,cold-region engineering,and climate change.In this study,the authors ... The active layer thickness(ALT)in permafrost regions,which affects water and energy exchange,is a key variable for assessing hydrological processes,cold-region engineering,and climate change.In this study,the authors analyzed the variation trends and relative changes of simulated ALTs using the Chinese Academy of Sciences Land Surface Model(CAS-LSM)and the Chinese Academy of Sciences Flexible Global Ocean-Atmosphere-Land System Model,gridpoint version 3(CAS-FGOALS-g3).Firstly,the simulated ALTs produced by CAS-LSM were shown to be reasonable by comparing them with Circumpolar Active Layer Monitoring observations.Then,the authors simulated the ALTs from 1979 to 2014,and their relative changes across the entire Northern Hemisphere from 2015 to 2100.It is shown that the ALTs have an increasing trend.From 1979 to 2014,the average ALTs and their variation trends over all permafrost regions were 1.08 m and 0.33 cm yr-1,respectively.The relative changes of the ALTs ranged from 1%to 58%,and the average relative change was 10.9%.The variation trends of the ALTs were basically consistent with the variation trends of the 2-m air temperature.By 2100,the relative changes of ALTs are predicted to be 10.3%,14.6%,30.1%,and 51%,respectively,under the four considered hypothetical climate scenarios(SSP-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5).This study indicates that climate change has a substantial impact on ALTs,and our results can help in understanding the responses of the ALTs of permafrost due to climate change. 展开更多
关键词 Active layer thickness CAS-LSM Variation trends Relative changes Climate change
下载PDF
Effect of layer thickness and voxel size inversion on leaf area density based on the voxel-based canopy profiling method
15
作者 Yan Chen Jian Liu +5 位作者 Xiong Yao Yangbo Deng Zhenbang Hao Lingchen Lin Nankun Wu Kunyong Yu 《Journal of Forestry Research》 SCIE CAS CSCD 2022年第5期1545-1558,共14页
Voxel-based canopy profiling is commonly used to determine small-scale leaf area.Layer thickness and voxel size impact accuracy when using this method.Here,we determined the optimal combination of layer thickness and ... Voxel-based canopy profiling is commonly used to determine small-scale leaf area.Layer thickness and voxel size impact accuracy when using this method.Here,we determined the optimal combination of layer thickness and voxel size to estimate leaf area density accurately.Terrestrial LiDAR Stonex X300 was used to generate point cloud data for Masson pines(Pinus massoniana).The canopy layer was stratified into 0.10-1.00-m-thick layers,while voxel size was 0.01-0.10 m.The leaf area density of individual trees was estimated using leaf area indices for the upper,middle,and lower canopy and the overall canopy.The true leaf area index,obtained by layered harvesting,was used to verify the inversion results.Leaf area density was inverted by nine combinations of layer thickness and voxel size.The average relative accuracy and mean estimated accuracy of these combined inversion results exceeded 80%.When layer thickness was 1.00 m and voxel size 0.05 m,inversion was closest to the true value.The average relative accuracy was 92.58%,mean estimated accuracy 98.00%,and root mean square error 0.17.The combination of leaf area density and index was accurately retrieved.In conclusion,nondestructive voxel-based canopy profiling proved suitable for inverting the leaf area density of Masson pine in Hetian Town,Fujian Province. 展开更多
关键词 Terrestrial LiDAR Leaf area density Pinus massoniana Voxel-based canopy profiling method layer thickness Voxel size
下载PDF
Determination of the Thickness and Medium of Covering Soil for Land Reclamation 被引量:27
16
作者 冯全洲 徐恒力 《Agricultural Science & Technology》 CAS 2009年第4期183-188,共6页
Land reclamation is a process of ecosystem reconstruction, for which it is very important to keep co-adaptation between plants and the below ground habitat. In order to keep the co-adaptation among plant species, thic... Land reclamation is a process of ecosystem reconstruction, for which it is very important to keep co-adaptation between plants and the below ground habitat. In order to keep the co-adaptation among plant species, thickness of covering soil and medium of covering soil to establish a self-regulating ecosystem, the thickness of covering soil of land reclamation for plants in different living forms by synusia structure of plant below-ground habitat and medium of covering soil by ecological factors of plant below-ground habitat were studied. Synusia structure of plant below-ground habitat was recognized through investigation on structure and root of plant community, and ecological factors were determined through soil profile investigation. The thickness and medium of covering soil of land reclamation for the tree, the shrub and the herb were proposed. 展开更多
关键词 Land reclamation Plant below-ground habitat Circle layer of root mass thickness of covering soil
下载PDF
Methods for Estimating the Ultimate Bearing Capacity of Layered Foundations
17
作者 袁凡凡 闫澍旺 《Transactions of Tianjin University》 EI CAS 2003年第4期330-333,共4页
The Meyerhof and Hanna′s(M-H) method to estimate the ultimate bearing capacity of layered foundations was improved. The experimental results of the load tests in Tianjin New Harbor were compared with predictions with... The Meyerhof and Hanna′s(M-H) method to estimate the ultimate bearing capacity of layered foundations was improved. The experimental results of the load tests in Tianjin New Harbor were compared with predictions with the method recommended by the code for the foundations of harbor engineering, i.e. Hansen′s method and the improved M-H method. The results of the comparisons implied that the code and the improved M-H method could give a better prediction. 展开更多
关键词 ultimate bearing capacity layered foundations Meyerhof and Hanna′s method
下载PDF
Prediction of methane emissions during the extraction of close-to-roof layer of a seam of large thickness
18
作者 KRAUSE Eugeniusz QU Xian-chao 《Journal of Coal Science & Engineering(China)》 2012年第4期337-343,共7页
Prediction of methane emissions at the stage of longwall planning constitutes the basis for the determination of the appropriate method and parameters of ventilation and selection of prevention means including the met... Prediction of methane emissions at the stage of longwall planning constitutes the basis for the determination of the appropriate method and parameters of ventilation and selection of prevention means including the methane drainage technol- ogy. The growth of methane saturation of coal seams with the extraction depth, with simultaneously increasing output concen- tration, contributes to the increase of the quantity of methane emitted into longwall areas. The subject matter of the article has been directed at the predicted quantity of methane emissions into planned longwalls with roof caving in the layer of seams adjacent to the roof of large thickness. The performed prognostic calculations of methane emissions into the longwall working were referred to two sources, i.e. methane liberated during coal mining by means of a cutter-loader and methane originating from the degasification of the floor layer destressed by the longwall conducted in the close-to-roof layer. The calculations of predictions allow to refer to the planned longwall, on account of the emitting methane, with possible and safe output quantity. Planning of extraction in the close-to-roof layer of a seam of large thickness with roof caving is especially important in con- ditions of increasing methane saturation with the depth of deposition and should be preceded by a prognostic analysis for de- termining the extraction possibilities of the planned longwall. 展开更多
关键词 methane emission EXTRACTION close-to-roof layer coal seam large thickness LONGWALL PREDICTION
下载PDF
Regulation of the Reacted Layer Thickness in a Gas-Solid Reacting System
19
作者 Miguel A. Barron Dulce Y. Medina Gabriel Plascencia 《Intelligent Control and Automation》 2014年第3期91-96,共6页
A mathematical model for the analysis of a gas-solid reacting system is presented. This model is an alternative to the classical shrinking-core model. The model has a structure that can be easily transformed into a ca... A mathematical model for the analysis of a gas-solid reacting system is presented. This model is an alternative to the classical shrinking-core model. The model has a structure that can be easily transformed into a canonical control form, which is proper for controller synthesis. Analytical solution of the model to describe the open-loop behavior is expressed in terms of the Lambert function. The Lambert function is evaluated from aTaylorexpansion series. Besides, a controller is proposed to regulate the reacted layer thickness using initially the diffusion coefficient as control input. The control law is synthesized employing the feedback linearization technique. Main contributions of this work are the synthesis of the layer thickness controller, and the employment of the process temperature as substitute of the diffusion coefficient as the control input. 展开更多
关键词 Diffusion COEFFICIENT FEEDBACK LINEARIZATION GAS-SOLID SYSTEM Lambert Function Reacted layer thickness REGULATION
下载PDF
Anti-vascular endothelial growth factor drugs combined with laser photocoagulation maintain retinal ganglion cell integrity in patients with diabetic macular edema: study protocol for a prospective, non-randomized, controlled clinical trial
20
作者 Xiangjun Li Chunyan Li +5 位作者 Hai Huang Dan Bai Jingyi Wang Anqi Chen Yu Gong Ying Leng 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第4期923-928,共6页
The integrity of retinal ganglion cells is tightly associated with diabetic macular degeneration that leads to damage and death of retinal ganglion cells,affecting vision.The major clinical treatments for diabetic mac... The integrity of retinal ganglion cells is tightly associated with diabetic macular degeneration that leads to damage and death of retinal ganglion cells,affecting vision.The major clinical treatments for diabetic macular edema are anti-vascular endothelial growth factor drugs and laser photocoagulation.However,although the macular thickness can be normalized with each of these two therapies used alone,the vision does not improve in many patients.This might result from the incomplete recovery of retinal ganglion cell injury.Therefore,a prospective,non-randomized,controlled clinical trial was designed to investigate the effect of anti-vascular endothelial growth factor drugs combined with laser photocoagulation on the integrity of retinal ganglion cells in patients with diabetic macular edema and its relationship with vision recovery.In this trial,150 patients with diabetic macular edema will be equally divided into three groups according to therapeutic methods,followed by treatment with anti-vascular endothelial growth factor drugs,laser photocoagulation therapy,and their combination.All patients will be followed up for 12 months.The primary outcome measure is retinal ganglion cell-inner plexiform layer thickness at 12 months after treatment.The secondary outcome measures include retinal ganglion cell-inner plexiform layer thickness before and 1,3,6,and 9 months after treatment,retinal nerve fiber layer thickness,best-corrected visual acuity,macular area thickness,and choroidal thickness before and 1,3,6,9,and 12 months after treatment.Safety measure is the incidence of adverse events at 1,3,6,9,and 12 months after treatment.The study protocol hopes to validate the better efficacy and safety of the combined treatment in patients with diabetic macula compared with the other two monotherapies alone during the 12-month follow-up period.The trial is designed to focus on clarifying the time-effect relationship between imaging measures related to the integrity of retinal ganglion cells and best-corrected visual acuity.The trial protocol was approved by the Medical Ethics Committee of the Affiliated Hospital of Beihua University with approval No.(2023)(26)on April 25,2023,and was registered with the Chinese Clinical Trial Registry(registration number:ChiCTR2300072478,June 14,2023,protocol version:2.0). 展开更多
关键词 choroidal thickness diabetic macular edema laser photocoagulation retinal ganglion cell-inner plexiform layer thickness retinal ganglion cells retinal nerve fiber layer thickness thickness of the macular area vascular endothelial growth factor visual acuity
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部