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基于湍流模型的飞行器温度场数值仿真研究
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作者 范福强 邢素霞 张俊举 《激光与红外》 CAS CSCD 北大核心 2024年第5期766-773,共8页
飞行器红外成像仿真需要不同飞行条件下的温度场分布。本文利用标准(Standard)k-ε模型、剪切应力传输(SST)k-ε模型和Spalart-Allmaras(S-A)模型分别进行数值模拟仿真计算,研究不同飞行速度和飞行高度下的飞行器温度场分布,并对不同模... 飞行器红外成像仿真需要不同飞行条件下的温度场分布。本文利用标准(Standard)k-ε模型、剪切应力传输(SST)k-ε模型和Spalart-Allmaras(S-A)模型分别进行数值模拟仿真计算,研究不同飞行速度和飞行高度下的飞行器温度场分布,并对不同模型的结果进行对比分析。首先,利用MultiGen Creator软件对飞行器进行三维建模;其次采用Hypemesh软件和Fluent meshing软件中进行面网格划分和体网格划分,最后采用Fluent 2022R1软件仿真飞行器静态温度场分布,通过改变湍流模型与边界条件设置,对不同飞行速度和不同高度下飞行器温度场进行数值模拟仿真,并与理论结果进行了对比分析。实验结果显示,3种湍流模型均能较好的模拟飞行器蒙皮与尾喷管内壁壁面温度值。飞行器蒙皮温度随着飞行马赫数的增加不断升高;随着飞行高度的升高而不断地降低,与理论结果变化规律一致。在尾喷管内壁面温度仿真中,3种湍流模型仿真的内壁面温度最高相差21 K,相对误差在1.8%左右,在红外仿真中近似忽略不计,故3种湍流模型均适合尾喷管内壁面温度场仿真。在蒙皮温度场仿真中,3种湍流模型仿真计算的蒙皮平均温度值与理论温度值的相对误差均在5%以内,均可满足红外成像仿真的温度差值要求,其中k-ε模型在蒙皮温度场模拟中与理论温度值最为接近,因此k-ε模型精度更高,更适合于飞行器的流场仿真,能更好地仿真出空气动力加热对飞行器温度场的影响。 展开更多
关键词 Standard k-ε模型 SST k-ε模型 S-A模型 飞行器 温度场模拟
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The impact of the Rural Minimum Living Standard Guarantee(Rural Dibao)Program on child nutrition outcomes 被引量:1
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作者 Dian Chen Xiangming Fang +3 位作者 Yu Chen Xiaodong Zheng Zhuo Chen Rodney B.W.Smith 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第2期444-456,共13页
The Rural Minimum Living Standard Guarantee(Rural Dibao)is an important unconditional cash transfer program to alleviate poverty in rural China.Despite the importance of children’s nutrition in breaking poverty cycle... The Rural Minimum Living Standard Guarantee(Rural Dibao)is an important unconditional cash transfer program to alleviate poverty in rural China.Despite the importance of children’s nutrition in breaking poverty cycles,little is known about the impact of Rural Dibao on child nutrition outcomes.Using China Family Panel Studies(CFPS),this paper examines the effects of Rural Dibao on child nutrition outcomes and investigates potential pathways and heterogeneous effects.We exploit propensity score matching and difference-in-differences techniques to evaluate the effects of the Rural Dibao program on child nutrition outcomes.Our results suggest that Rural Dibao significantly impacts the nutrition outcomes of children up to 15 years of age.Specifically,our results suggest that Rural Dibao improves child height-to-age z-scores by 1.05 standard deviations and lowers the probability of stunting by 11.9 percentage points.Additional analyses suggest that increased protein intake is the main pathway through which Rural Dibao participation contributes to better nutrition outcomes.We also find that the effect of the program is more pronounced among girls,children who are non-left-behind or live with highly educated mothers,and those from low-income families and poor areas.Our findings suggest that Rural Dibao participation helps improve child nutrition outcomes through improving diet quality. 展开更多
关键词 Rural Minimum Living Standard Guarantee NUTRITION height-to-age z-scores STUNTING rural China
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Development of a new cerebral ischemia reperfusion model of Mongolian gerbils and standardized evaluation system 被引量:1
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作者 Ying Wu Caijiao Hu +9 位作者 Zhihui Li Feiyang Li Jianyi Lv Meng Guo Xin Liu Changlong Li Xueyun Huo Zhenwen Chen Lifeng Yang Xiaoyan Du 《Animal Models and Experimental Medicine》 CAS CSCD 2024年第1期48-55,共8页
Background:The Mongolian gerbil is an excellent laboratory animal for preparing the cerebral ischemia model due to its inherent deficiency in the circle of Willis.However,the low incidence and unpredictability of symp... Background:The Mongolian gerbil is an excellent laboratory animal for preparing the cerebral ischemia model due to its inherent deficiency in the circle of Willis.However,the low incidence and unpredictability of symptoms are caused by numerous complex variant types of the circle.Additionally,the lack of an evaluation system for the cer-ebral ischemia/reperfusion(I/R)model of gerbils has shackled the application of this model.Methods:We created a symptom-oriented principle and detailed neurobehavioral scoring criteria.At different time points of reperfusion,we analyzed the alteration in locomotion by rotarod test and grip force score,infarct volume by triphenyltetrazo-lium chloride(TTC)staining,neuron loss using Nissl staining,and histological charac-teristics using hematoxylin-eosin(H&E)straining.Results:With a successful model rate of 56%,32 of the 57 gerbils operated by our method harbored typical features of cerebral I/R injury,and the mortality rate in the male gerbils was significantly higher than that in the female gerbils.The suc-cessfully prepared I/R gerbils demonstrated a significant reduction in motility and grip strength at 1 day after reperfusion;formed obvious infarction;exhibited typi-cal pathological features,such as tissue edema,neuronal atrophy and death,and vacuolated structures;and were partially recovered with the extension of reperfu-sion time.Conclusion:This study developed a new method for the unilateral common carotid artery ligation I/R model of gerbil and established a standardized evaluation system for this model,which could provide a new cerebral I/R model of gerbils with more practical applications. 展开更多
关键词 ISCHEMIA/REPERFUSION Mongolian gerbil standardized model system unilateral carotid occlusion
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2021-2022年蒙古标准化发展分析:基于获批标准涉及领域的统计 被引量:1
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作者 毕晓宇 李占元 +7 位作者 耿强 高飞 赵梦莎 邢都林 蒋柠 徐晓强 李彦男 李夏伟 《China Standardization》 2024年第2期68-72,共5页
Mongolia,a key partner in the Belt and Road Initiative,is fully dedicated to fostering regional cooperation and connectivity.Standardization has emerged as a vital field with far-reaching influence for regional trade ... Mongolia,a key partner in the Belt and Road Initiative,is fully dedicated to fostering regional cooperation and connectivity.Standardization has emerged as a vital field with far-reaching influence for regional trade cooperation.This paper makes an in-depth analysis of the standards approved in Mongolia in 2021 and 2022,offering a fresh perspective of the past two years’standardization development in the country.The primary objective is to present an updated account of Mongolia’s standardization efforts and to facilitate regional cooperation and exchange in standardization. 展开更多
关键词 Mongolia STANDARDIZATION standards development approved standards fields and quantities
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智慧城轨车地一体化机电系统标准体系构建研究 被引量:1
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作者 杨廷志 《China Standardization》 2024年第1期56-59,共4页
With the rapid development and application of emerging information technologies such as cloud computing,big data,artificial intelligence,5G,satellite communication,and blockchain in urban rail transit,China’s urban r... With the rapid development and application of emerging information technologies such as cloud computing,big data,artificial intelligence,5G,satellite communication,and blockchain in urban rail transit,China’s urban rail transit has entered an era of intelligent transformation and upgrading.The development of intelligent systems and the construction of smart urban rail transit have formed a consensus in the industry.The electromechanical system is an important component of urban rail transit engineering,covering power supply stations,vehicles,stations,and lines.The depot and control center are important support for promoting the development of urban rail transit towards informatization and intelligence.However,research on the technical standards for the smart urban rail vehicle-ground integrated electromechanical system has just begun,and a technical standards system has not yet been formed,which cannot better support the electromechanical system.Therefore,it is necessary to conduct research on the technical standards system,propose the common criteria structure and standards list of the standards system,which can provide reference and guidance for the planning and establishment of China’s smart urban rail standards system. 展开更多
关键词 smart urban rail vehicles vehicle-ground integration electromechanical system standards system standards list
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Spatiotemporal characteristics of cultivated land use eco-efficiency and its influencing factors in China from 2000 to 2020 被引量:1
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作者 LI Shaoting MU Na +1 位作者 REN Yanjun Thomas GLAUBEN 《Journal of Arid Land》 SCIE CSCD 2024年第3期396-414,共19页
Improving cultivated land use eco-efficiency(CLUE)can effectively promote agricultural sustainability,particularly in developing countries where CLUE is generally low.This study used provincial-level data from China t... Improving cultivated land use eco-efficiency(CLUE)can effectively promote agricultural sustainability,particularly in developing countries where CLUE is generally low.This study used provincial-level data from China to evaluate the spatiotemporal evolution of CLUE from 2000 to 2020 and identified the influencing factors of CLUE by using a panel Tobit model.In addition,given the undesirable outputs of agricultural production,we incorporated carbon emissions and nonpoint source pollution into the global benchmark-undesirable output-super efficiency-slacks-based measure(GB-US-SBM)model,which combines global benchmark technology,undesirable output,super efficiency,and slacks-based measure.The results indicated that there was an upward trend in CLUE in China from 2000 to 2020,with an increase rate of 2.62%.The temporal evolution of CLUE in China could be classified into three distinct stages:a period of fluctuating decrease(2000-2007),a phase of gradual increase(2008-2014),and a period of rapid growth(2015-2020).The major grain-producing areas(MPAs)had a lower CLUE than their counterparts,namely,non-major grain-production areas(non-MPAs).The spatial agglomeration effect followed a northeast-southwest strip distribution;and the movement path of barycentre revealed a"P"shape,with Luoyang City,Henan Province,as the centre.In terms of influencing factors of CLUE,investment in science and technology played the most vital role in improving CLUE,while irrigation index had the most negative effect.It should be noted that these two influencing factors had different impacts on MPAs and non-MPAs.Therefore,relevant departments should formulate policies to enhance the level of science and technology,improve irrigation condition,and promote sustainable utilization of cultivated land. 展开更多
关键词 cultivated land use eco-efficiency(CLUE) slacks-based measure(SBM)model barycentre model standard deviation ellipse(SDE) panel Tobit model carbon emissions nonpoint source pollution
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三段式嵌套顺序统计量的分布及应用
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作者 樊湉航 孙平 《许昌学院学报》 CAS 2024年第5期19-24,共6页
顺序统计量在非参数统计分析中有着广泛的应用,嵌套顺序统计量的分布则依赖于具体的嵌套结构以及随机变量的分布特性.在研究三段式嵌套顺序统计量的分布时,可以将问题转化为嵌套积分,通过对相应的嵌套单形进行多重积分得到三段式嵌套顺... 顺序统计量在非参数统计分析中有着广泛的应用,嵌套顺序统计量的分布则依赖于具体的嵌套结构以及随机变量的分布特性.在研究三段式嵌套顺序统计量的分布时,可以将问题转化为嵌套积分,通过对相应的嵌套单形进行多重积分得到三段式嵌套顺序统计量的分布.这种分析方法的应用十分广泛,由于Standard Young Tableaux (SYT)的每一行对应一组独立的顺序统计量,因此文章将其应用于SYT的计数问题.此外,文章还将三段式嵌套顺序统计量的分布应用于选票问题. 展开更多
关键词 顺序统计量 多重积分 Standard Young Tableaux
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Performance and Safety Improvement of Induction Motors based on Testing and Evaluation Standards
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作者 Nkosinathi S.Khumalo Ntombizotwa P.Memane Udochukwu B.Akuru 《CES Transactions on Electrical Machines and Systems》 EI CSCD 2024年第3期310-318,共9页
The induction motor,which converts electrical energy into mechanical energy,has been recognized as the cornerstone of industrialization.The rotor of an induction motor can be either a squirrel cage rotor or a wound-ty... The induction motor,which converts electrical energy into mechanical energy,has been recognized as the cornerstone of industrialization.The rotor of an induction motor can be either a squirrel cage rotor or a wound-type rotor,both existing as magnetless topologies.Three-phase squirrel cage induction motors are frequently utilized in industrial drives because they are dependable,have high starting torque,are selfstarting and affordable.Single-phase induction motors,on the other hand,are commonly used for small loads such as domestic appliances in form of modest fans,pumps and electric power tools.In South Africa,there have been reports of fires and explosions resulting in live and property loss because of induction motors that have not been thoroughly tested or are incorrectly labelled in terms of ratings,electrical safety and performance.The goal of this study is targeted at preventing end-user injuries and failures caused by non-compliant induction motors,by evaluating locally manufactured/imported induction motors based on tests and evaluation from standards(IEC and SANS).The study is conducted using experimental procedures at the Explosion Prevention Technology and Rotating Machines(EPT and RM)laboratory,South African Bureau of Standards(SABS),South Africa.The main finding from the study shows differences in the nameplate characteristics of various induction motors which could have detrimental effects such as production and operational downtime in their end-use industries,at later stages. 展开更多
关键词 COMPLIANCE Induction motors International Electro-Technical standards(IEC) NAMEPLATE Experimental tests South African National Standards(SANS)
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Standardized ileal digestibility of amino acids in soybean meal fed to non-pregnant and pregnant sows
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作者 Ke Wang Ya Wang +11 位作者 Lei Guo Yong Zhuo Lun Hua Lianqiang Che Shengyu Xu Ruinan Zhang Jian Li Bin Feng Zhengfeng Fang Xuemei Jiang Yan Lin De Wu 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2024年第1期362-373,共12页
Background Two studies were designed to determine standard ileal crude protein(CP)and amino acid(AA)digestibility of soybean meal(SBM)from different origins fed to non-pregnant and pregnant sows.Seven solvent-extracte... Background Two studies were designed to determine standard ileal crude protein(CP)and amino acid(AA)digestibility of soybean meal(SBM)from different origins fed to non-pregnant and pregnant sows.Seven solvent-extracted SBMs from soybeans produced in the USA,Brazil,and China were selected.In Exp.1,eight different diets were created:a nitrogen(N)-free diet and 7 experimental diets containing SBM from different origins as the only N source.Eight non-pregnant,multiparous sows were arranged in an 8×8 Latin square design(8 periods and 8 diets).In Exp.2,the diet formula was the same as in Exp.1.Eight gestating sows(parity 3)were assigned to 4 different diets in a replicated 4×3 Youden square design(three periods and four diets)in mid-gestation and again in late-gestation stages.Results When fed to non-pregnant and late-gestating sows,the standardized ileal digestibility(SID)of CP and most AAs from different SBM were not significantly different(P>0.05).When fed to mid-gestating sows,the SID values for Arg,His,Lys,Phe,Cys,Gly,Ser,and Tyr in SBM 1 were lower than in SBM 4 and 5(P<0.05),whereas SID for Leu from SBM 5 was higher than in SBM 1 and 4(P<0.05).SID values for Ile,Ala,and Asp from SBM 4 were lower than in SBM 1 and 5(P<0.05).Sows had significantly greater SID values for Lys,Ala,and Asp during mid-gestation when compared with late-gestation stages(P<0.05).Mid-gestating sows had greater SID value for Val and lower SID value for Tyr when compared with non-pregnant and late-gestating sows(P<0.01),whereas non-pregnant sows had significantly greater SID value for Met when compared with gestating sows(P<0.01).Conclusions When fed to mid-gestating sows,the SID values for most AAs varied among SBM samples.The SID values for Lys,Met,Val,Ala,Asp,and Tyr in SBM were affected by sow gestation stages.Our findings provide a cornerstone for accurate SBM use in sow diets. 展开更多
关键词 Amino acids SOWS Soybean meal Standardized ileal digestibility
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Research on batch multielement rapid quantitative analysis based on the standard curve-assisted calibration-free laserinduced breakdown spectroscopy method
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作者 Weiwei HAN Duixiong SUN +7 位作者 Guoding ZHANG Honglin WANG Kai GUO Yuzhuo ZHANG Haoliang WANG Denghong ZHANG Chenzhong DONG Maogen SU 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第9期156-164,共9页
This study proposes a batch rapid quantitative analysis method for multiple elements by combining the advantages of standard curve(SC)and calibration-free laser-induced breakdown spectroscopy(CF-LIBS)technology to ach... This study proposes a batch rapid quantitative analysis method for multiple elements by combining the advantages of standard curve(SC)and calibration-free laser-induced breakdown spectroscopy(CF-LIBS)technology to achieve synchronous,rapid,and accurate measurement of elements in a large number of samples,namely,SC-assisted CF-LIBS.Al alloy standard samples,divided into calibration and test samples,were applied to validate the proposed method.SC was built based on the characteristic line of Pb and Cr in the calibration sample,and the contents of Pb and Cr in the test sample were calculated with relative errors of 6%and 4%,respectively.SC built using Cr with multiple characteristic lines yielded better calculation results.The relative contents of ten elements in the test sample were calculated using CF-LIBS.Subsequently,the SC-assisted CF-LIBS was executed,with the majority of the calculation relative errors falling within the range of 2%-5%.Finally,the Al and Na contents of the Al alloy were predicted.The results demonstrate that it effectively enables the rapid and accurate quantitative analysis of multiple elements after a single-element SC analysis of the tested samples.Furthermore,this quantitative analysis method was successfully applied to soil and Astragalus samples,realizing an accurate calculation of the contents of multiple elements.Thus,it is important to advance the LIBS quantitative analysis and its related applications. 展开更多
关键词 laser-induced breakdown spectroscopy standard curve quantitative analysis multielement
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Spatiotemporal patterns and drivers of cultivated land conversion in Inner Mongolia Autonomous Region,northern China
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作者 Xijiri ZHOU Ruiping +1 位作者 BAO Baorong Burenjirigala 《Journal of Arid Land》 SCIE CSCD 2024年第9期1197-1213,共17页
Protection and optimization of cultivated land resources are of great significance to national food security.Cultivated land conversion in northern China has increased in recent years due to the industrialization and ... Protection and optimization of cultivated land resources are of great significance to national food security.Cultivated land conversion in northern China has increased in recent years due to the industrialization and urbanization of society.However,the assessment of cultivated land conversion in this area is insufficient,posing a potential risk to cultivated land resources.This study evaluated the evolution and spatiotemporal patterns of cultivated land conversion in Inner Mongolia Autonomous Region,China,and the driving factors to improve rational utilization and to protect cultivated land resources.The spatiotemporal patterns of cultivated land conversion in Inner Mongolia were analyzed using the cultivated land conversion index,kernel density analysis,a standard deviation ellipse model,and a geographic detector.Results showed that from 2000 to 2020,the trends in cultivated land conversion area and rate in Inner Mongolia exhibited fluctuating growth,with the total area of cultivated land conversion reaching 7307.59 km^(2) at a rate of 6.69%.Spatial distribution of cultivated land conversion was primarily concentrated in the Hetao Plain,Nengjiang Plain,Liaohe Plain,and the Hohhot-Baotou-Ordos urban agglomeration.Moreover,the standard deviational ellipse of cultivated land conversion in Inner Mongolia exhibited a directional southwest-northeast-southwest-northeast distribution,with the northeast-southwest direction identified as the main driving force of spatial change in cultivated land conversion.Meanwhile,cultivated land conversion exhibited an increase-decrease-increase change process,indicating that spatial distribution of cultivated land conversion in Inner Mongolia became gradually apparent within the study period.The geographic detector results further revealed that the main driving factors of cultivated land conversion in Inner Mongolia were the share of secondary and tertiary industries and per-unit area yield of grain,with explanatory rates of 57.00%,55.00%,and 51.00%,respectively.Additionally,improved agricultural production efficiency and the coordinated development of population urbanization and industry resulted in cultivated land conversion.Collectively,the findings of this study indicated that,from 2000 to 2020,the cultivated land conversion in Inner Mongolia was significant and fluctuated in time,and had strong spatial heterogeneity.The primary drivers of these events included the effects of agriculture,population,and social economy. 展开更多
关键词 cultivated land conversion spatiotemporal variation standard deviation elliptical models geographic detector northern China
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PDE Standardization Analysis and Solution of TypicalMechanics Problems
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作者 Ningjie Wang Yihao Wang +1 位作者 Yongle Pei Luxian Li 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第10期171-186,共16页
A numerical approach is an effective means of solving boundary value problems(BVPs).This study focuses on physical problems with general partial differential equations(PDEs).It investigates the solution approach throu... A numerical approach is an effective means of solving boundary value problems(BVPs).This study focuses on physical problems with general partial differential equations(PDEs).It investigates the solution approach through the standard forms of the PDE module in COMSOL.Two typical mechanics problems are exemplified:The deflection of a thin plate,which can be addressed with the dedicated finite element module,and the stress of a pure bending beamthat cannot be tackled.The procedure for the two problems regarding the three standard forms required by the PDE module is detailed.The results were in good agreement with the literature,indicating that the PDE module provides a promising means to solve complex PDEs,especially for those a dedicated finite element module has yet to be developed. 展开更多
关键词 Three standard forms expression input PDE module deflection solution stress solution
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Standardization of meibomian gland dysfunction in an Egyptian population sample using a non-contact meibography technique
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作者 Ahmed Mohamed Karara Zeinab El-Sanabary +2 位作者 Mostafa Ali El-Helw Tamer Ahmed Macky Mohamad Amr Salah Eddin Abdelhakim 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第1期61-65,共5页
AIM:To develop normative data for meibomian gland dysfunction(MGD)parameters,using non-contact meibography technique of Sirius Costruzione Strumenti Oftalmici(CSO)machine,in an Egyptian population sample.METHODS:Obser... AIM:To develop normative data for meibomian gland dysfunction(MGD)parameters,using non-contact meibography technique of Sirius Costruzione Strumenti Oftalmici(CSO)machine,in an Egyptian population sample.METHODS:Observational,cross-sectional,analytic study,in which 104 Egyptian volunteers were included.Both upper lids were examined,using“Sirius CSO”machine.Each eyelid was given a degree of meibomian gland loss(MGL),which was calculated by the software of the machine.RESULTS:Mean percentage MGL in right upper lid was of 30.9%±12.6%,and that of left upper lid was 32.6%±11.8%.Thirty-four volunteers(32.7%)had first-degree MGL in their right upper lid,and 67.3%had second-degree loss.One volunteer(1%)had zero-degree MGL in left upper lid,28(26.9%)had first-degree loss,and 75(72.1%)had second-degree loss.Degree of MGL in right upper eyelid was not related to age,but degree of MGL in left upper eyelid increased with age.There was statistically significant difference between both genders for degree of MGL in right eye(P=0.036)and in left eye(P=0.027).CONCLUSION:Noncontact meibography is a useful non-invasive tool for diagnosing MGL.MGL is diagnosed in 100%of apparently normal individuals;26.9%-32.7%of which have first-degree MGL,and 67.3%-72.1%have second-degree MGL. 展开更多
关键词 Egyptian population meibomian gland dysfunction non-contact meibography STANDARDIZATION upper lid
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Quality assessment of the Topo-Iberia CGPS stations and data quality's effects on postfit ionosphere-free phase residuals
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作者 Juan A.García-Armenteros 《Geodesy and Geodynamics》 EI CSCD 2024年第2期189-199,共11页
This paper analyzed GPS data from the Topo-Iberia network spanning almost 12 years(2008-2020).The data quality information for all 26 Topo-Iberia stations is provided for the first time,complementing the Spanish Geolo... This paper analyzed GPS data from the Topo-Iberia network spanning almost 12 years(2008-2020).The data quality information for all 26 Topo-Iberia stations is provided for the first time,complementing the Spanish Geological Survey’s storage work.Data analyses based on quality indicators obtained using TEQC have been carried out.The guidelines and data quality information from the IGS stations have been considered as the quality references,with the stations ALJI,EPCU,and TIOU standing out as the worst stations,while on the contrary,FUEN,PALM,PILA,and TRIA meet the quality requirements to become an IGS station.The relationship between the GPS data quality and their GAMIT-and Gipsy X-derived postfit ionosphere-free phase residuals has also been investigated,and the results reveal an inversely proportional relationship.It has been found that the stations showing an increase in elevation of the horizon line,also show an increase in cycle slips and multipath,are among the poorest quality stations,and among those with the highest postfit RMS of phase residuals.Moreover,the evolution of the vegetation around the antenna should be considered as it could cause a progressive loss of quality,which is not complying with the IGS standards.The quality assessment shows that the Topo-Iberia stations are appropriate for geodetic purposes,but permanent monitoring would be necessary to avoid the least possible loss of data and quality.In addition,a method to characterize the GNSS data quality is proposed. 展开更多
关键词 GPS dataquality's effects IGS quality standard Postfit LC phase residual Qualityassessment Topo-Iberia CGPS network
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A new calibration method for radon detector in seismic systems
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作者 Hongwei Ren Yaowei Liu 《Earthquake Science》 2024年第5期445-458,共14页
Radon observation is an important measurement item of seismic precursor network observation.The radon detector calibration is a key technical link for ensuring radon observation accuracy.At present,the radon detector ... Radon observation is an important measurement item of seismic precursor network observation.The radon detector calibration is a key technical link for ensuring radon observation accuracy.At present,the radon detector calibration in seismic systems in China is faced with a series of bottleneck problems,such as aging and scrap,acquisition difficulties,high supervision costs,and transportation limitations of radon sources.As a result,a large number of radon detectors cannot be accurately calibrated regularly,seriously affecting the accuracy and reliability of radon observation data in China.To solve this problem,a new calibration method for radon detectors was established.The advantage of this method is that the dangerous radioactive substance,i.e.,the radon source,can be avoided,but only“standard instruments”and water samples with certain dissolved radon concentrations can be used to realize radon detector calibration.This method avoids the risk of radioactive leakage and solves the current widespread difficulties and bottleneck of radon detector calibration in seismic systems in China.The comparison experiment with the traditional calibration method shows that the error of the calibration coefficient obtained by the new method is less than 5%compared with that by the traditional method,which meets the requirements of seismic observation systems,confirming the reliability of the new method.This new method can completely replace the traditional calibration method of using a radon source in seismic systems. 展开更多
关键词 radon detector CALIBRATION “standard instrument” scintillation chamber radon source
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Characteristics of laser-induced breakdown spectroscopy of liquid slag
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作者 董长言 于洪霞 +4 位作者 孙兰香 李洋 刘修业 周平 黄少文 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第2期86-93,共8页
Rapid online analysis of liquid slag is essential for optimizing the quality and energy efficiency of steel production. To investigate the key factors that affect the online measurement of refined slag using laser-ind... Rapid online analysis of liquid slag is essential for optimizing the quality and energy efficiency of steel production. To investigate the key factors that affect the online measurement of refined slag using laser-induced breakdown spectroscopy(LIBS), this study examined the effects of slag composition and temperature on the intensity and stability of the LIBS spectra. The experimental temperature was controlled at three levels: 1350℃, 1400℃, and 1450℃. The results showed that slag composition and temperature significantly affected the intensity and stability of the LIBS spectra. Increasing the Fe content and temperature in the slag reduces its viscosity, resulting in an enhanced intensity and stability of the LIBS spectra. Additionally, 42 refined slag samples were quantitatively analyzed for Fe, Si, Ca, Mg, Al, and Mn at 1350℃, 1400℃, and 1450℃.The normalized full spectrum combined with partial least squares(PLS) quantification modeling was used, using the Ca Ⅱ 317.91 nm spectral line as an internal standard. The results show that using the internal standard normalization method can significantly reduce the influence of spectral fluctuations. Meanwhile, a temperature of 1450℃ has been found to yield superior results compared to both 1350℃ and 1400℃, and it is advantageous to conduct a quantitative analysis of the slag when it is in a “water-like” state with low viscosity. 展开更多
关键词 laser-induced breakdown spectroscopy(LIBS) SLAG temperature COMPOSITION VISCOSITY internal standard normalization partial least squares(PLS)
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Effects of temperature and precipitation on drought trends in Xinjiang, China
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作者 YANG Jianhua LI Yaqian +3 位作者 ZHOU Lei ZHANG Zhenqing ZHOU Hongkui WU Jianjun 《Journal of Arid Land》 SCIE CSCD 2024年第8期1098-1117,共20页
The characteristics of drought in Xinjiang Uygur Autonomous Region(Xinjiang),China have changed due to changes in the spatiotemporal patterns of temperature and precipitation,however,the effects of temperature and pre... The characteristics of drought in Xinjiang Uygur Autonomous Region(Xinjiang),China have changed due to changes in the spatiotemporal patterns of temperature and precipitation,however,the effects of temperature and precipitation—the two most important factors influencing drought—have not yet been thoroughly explored in this region.In this study,we first calculated the standard precipitation evapotranspiration index(SPEI)in Xinjiang from 1980 to 2020 based on the monthly precipitation and monthly average temperature.Then the spatiotemporal characteristics of temperature,precipitation,and drought in Xinjiang from 1980 to 2020 were analyzed using the Theil-Sen median trend analysis method and Mann-Kendall test.A series of SPEI-based scenario-setting experiments by combining the observed and detrended climatic factors were utilized to quantify the effects of individual climatic factor(i.e.,temperature and precipitation).The results revealed that both temperature and precipitation had experienced increasing trends at most meteorological stations in Xinjiang from 1980 to 2020,especially the spring temperature and winter precipitation.Due to the influence of temperature,trends of intensifying drought have been observed at spring,summer,autumn,and annual scales.In addition,the drought trends in southern Xinjiang were more notable than those in northern Xinjiang.From 1980 to 2020,temperature trends exacerbated drought trends,but precipitation trends alleviated drought trends in Xinjiang.Most meteorological stations in Xinjiang exhibited temperature-dominated drought trend except in winter;in winter,most stations exhibited precipitation-dominated wetting trend.The findings of this study highlight the importance of the impact of temperature on drought in Xinjiang and deepen the understanding of the factors influencing drought. 展开更多
关键词 standardized precipitation evapotranspiration index(SPEI) climate change drought characteristics trend analysis arid area temperature trend contribution analysis
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A Dual Domain Robust Reversible Watermarking Algorithm for Frame Grouping Videos Using Scene Smoothness
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作者 Yucheng Liang Ke Niu +1 位作者 Yingnan Zhang Yifei Meng 《Computers, Materials & Continua》 SCIE EI 2024年第6期5143-5174,共32页
The proposed robust reversible watermarking algorithm addresses the compatibility challenges between robustness and reversibility in existing video watermarking techniques by leveraging scene smoothness for frame grou... The proposed robust reversible watermarking algorithm addresses the compatibility challenges between robustness and reversibility in existing video watermarking techniques by leveraging scene smoothness for frame grouping videos.Grounded in the H.264 video coding standard,the algorithm first employs traditional robust watermark stitching technology to embed watermark information in the low-frequency coefficient domain of the U channel.Subsequently,it utilizes histogram migration techniques in the high-frequency coefficient domain of the U channel to embed auxiliary information,enabling successful watermark extraction and lossless recovery of the original video content.Experimental results demonstrate the algorithm’s strong imperceptibility,with each embedded frame in the experimental videos achieving a mean peak signal-to-noise ratio of 49.3830 dB and a mean structural similarity of 0.9996.Compared with the three comparison algorithms,the performance of the two experimental indexes is improved by 7.59%and 0.4%on average.At the same time,the proposed algorithm has strong robustness to both offline and online attacks:In the face of offline attacks,the average normalized correlation coefficient between the extracted watermark and the original watermark is 0.9989,and the average bit error rate is 0.0089.In the face of online attacks,the normalized correlation coefficient between the extracted watermark and the original watermark is 0.8840,and the mean bit error rate is 0.2269.Compared with the three comparison algorithms,the performance of the two experimental indexes is improved by 1.27%and 18.16%on average,highlighting the algorithm’s robustness.Furthermore,the algorithm exhibits low computational complexity,with the mean encoding and the mean decoding time differentials during experimental video processing being 3.934 and 2.273 s,respectively,underscoring its practical utility. 展开更多
关键词 Robust reversible watermarking scene smoothness dual-domain U channel H.264 encoding standard
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The Making of a Health Profession:How Chinese Medicine Became a Nationally Registered Allied Health Profession in Australia
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作者 John L McDonald Judy B James 《Chinese Medicine and Culture》 2024年第1期51-62,共12页
In 2012, traditional Chinese medicine(TCM) practitioners in Australia became nationally-registered allied health professionals in three categories: acupuncturist, Chinese herbal medicine practitioner, and Chinese herb... In 2012, traditional Chinese medicine(TCM) practitioners in Australia became nationally-registered allied health professionals in three categories: acupuncturist, Chinese herbal medicine practitioner, and Chinese herbal medicine dispenser. Australia was the first Western country to introduce national registration for Chinese medicine, followed by Portugal and, recently, New Zealand. The practice of TCM in Australia can be traced back to the beginning of Chinese immigration to Australia during the Victorian Gold Rush which began in the 1850s. The process which led to national registration commenced in the early 1970s with the establishment of the first acupuncture courses. Decades of gradual development of courses from unaccredited part-time diplomas to accredited bachelor degrees, and the development, by the profession, of national consensus on educational standards were essential elements in the process which led to registration. Professional associations, such as the Australian Acupuncture and Chinese Medicine Association Ltd.(AACMA), also developed a framework of professional selfregulation, including Codes of Ethics, Codes of Conduct, ongoing professional development requirements and Infection Control Guidelines, and provided leadership in the development of the profession. After decades of tribalism and division within the TCM profession, the National Academic Standards Committee brought almost all stakeholders together to reach a consensus on the Australian Guidelines for Traditional Chinese Medicine Education which were published by AACMA in 2001. Professional associations also collaborated on joint submissions to the government in support of registration, which was introduced first in the state of Victoria in 2000, and subsequently became national in 2012. Despite national registration, some barriers still remain, and professional associations continue to lobby the federal government for inclusion in Medicare, chronic disease management scheme, and Veterans Affairs. 展开更多
关键词 ACUPUNCTURE Chinese medicine REGISTRATION Regulation Education Standards AUSTRALIA TCM
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Oils with different degree of saturation:effects on ileal digestibility of fat and corresponding additivity and bacterial community in growing pigs
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作者 Lu Wang Yifan Chen +2 位作者 Yuansen Yang Nuo Xiao Changhua Lai 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2024年第4期1657-1668,共12页
Background Oils are important sources of energy in pig diets.The combination of oils with different degree of saturation contributes to improve the utilization efficiency of the mixed oils and may reduce the cost of o... Background Oils are important sources of energy in pig diets.The combination of oils with different degree of saturation contributes to improve the utilization efficiency of the mixed oils and may reduce the cost of oil supplemented.An experiment was conducted to evaluate the effects of oils with different degree of saturation on the fat digestibility and corresponding additivity and bacterial community in growing pigs.Methods Eighteen crossbred(Duroc×Landrace×Yorkshire)barrows(initial body weight:29.3±2.8 kg)were surgically fitted with a T-cannula in the distal ileum.The experimental diets included a fat-free basal diet and 5 oil-added diets.The 5 oil-added diets were formulated by adding 6%oil with different ratio of unsaturated to saturated fatty acids(U:S)to the basal diet.The 5 oils were palm oil(U:S=1.2),canola oil(U:S=12.0),and palm oil and canola oil were mixed in different proportions to prepare a combination of U:S of 2.5,3.5 and 4.5,respectively.Results The apparent and standardized ileal digestibility(AID and SID)of fat and fatty acids increased linearly(P<0.05)as the U:S of dietary oils increased except for SID of fat and C18:2.The AID and SID of fat and fatty acids differed among the dietary treatments(P<0.05)except for SID of unsaturated fatty acids(UFA)and C18:2.Fitted one-slope broken-line analyses for the SID of fat,saturated fatty acids(SFA)and UFA indicated that the breakpoint for U:S of oil was 4.14(R^(2)=0.89,P<0.01),2.91(R^(2)=0.98,P<0.01)and 3.84(R^(2)=0.85,P<0.01),respectively.The determined SID of fat,C18:1,C18:2 and UFA in the mixtures was not different from the calculated SID of fat,C18:1,C18:2 and UFA.However,the determined SID of C16:0,C18:0 and SFA in the mixtures were greater than the calculated SID values(P<0.05).The abundance of Romboutsia and Turicibacter in pigs fed diet containing palm oil was greater than that in rapeseed oil treatment group,and the two bacteria were negatively correlated with SID of C16:0,C18:0 and SFA(P<0.05).Conclusions The optimal U:S for improving the utilization efficiency of mixed oil was 4.14.The SID of fat and UFA for palm oil and canola oil were additive in growing pigs,whereas the SID of SFA in the mixture of two oils was greater than the sum of the values of pure oils.Differences in fat digestibility caused by oils differing in degree of saturation has a significant impact on bacterial community in the foregut. 展开更多
关键词 ADDITIVITY Bacterial community Fat and fatty acids Growing pigs Ratio of unsaturated to saturated fatty acids Standardized ileal digestibility
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