检索结果-南通市图书馆

Novel approach for determining the optimal axial preload of a simulating rotary table spindle system

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第5期8卷 812-817页

作者： shan Xiao-biao XIE Tao CHEN Wei-shan School of Mechatronics Engineering Harbin Institute of Technology Harbin 15001 China

This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.

关键词： Three-axis simulating rotary table Axial position preload Stiffness Experimental modal analysis Finite elementanalysis

Creep crack growth in a Cr-Mo-V type steel: experimental observation and prediction

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第2期24卷 81-91页

作者： shan-Tung TU Key Laboratory of Safety Science of Pressurized System Ministry of Education School of Mechanical and Power Engineering East China University of Science and Technology

In this study, the creep crack growth （CCG） properties and fracture mechanism of a Cr-Mo-V steel at 566 C in compact tension （CT） specimens were investigated, and the CCG rate was predicted by using the NSW model. The results show that the CCG rate measured by CT specimens is much lower than that predicted by the NSW model under plane-strain state. This means that the NSW model prediction for the CCG rate of the steel is over-conservative. In addition, the CCG rate da/dt versus C measured by the experiments shows the piecewise linear relation on log-log scale instead of a single linear relation predicted by the NSW model. The main reasons for these results are that the actual creep fracture mechanism of the steel and the actual creep crack tip stress field in the CT specimens have not been fully captured in the NSW model. The experimental observation shows that the creep crack propagates in a discontinuous way （step by step） at meso-scale, and the cracks at micro-scale are usually formed by the growth and coalescence of voids on grain boundaries. The NSW model based on the creep ductility exhaustion approach may not correctly describe this creep fracture process. In addition, the opening stress and triaxial stress ahead of crack tips calculated by three-dimensional finite element method is lower than those predicted by the HRR stress field which is used in the NSW model under plane-strain state. The use of the high HRR stress field will cause high CCG rates. The change in the creep fracture mechanism at micro-scale in different ranges of C may cause the piecewise linear relation between the da/dt and C . Therefore, it is necessary to study the actual CCG mechanism in a wide range of C and the actual creep crack tip stress field to establish accurate CCG prediction models.

关键词： Creep crack growth Prediction NSW model Fracture mechanism Finite element method

Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第3期24卷 183-189页

作者： shan-Tung TU Key Laboratory of Safety Science of Pressurized System Ministry of EducationEast China University of Science and Technology

The creep behavior of the plasma sprayed NiCr and NiCrA1 coating/Nickel alloy 690 substrate systems at 1033 K was investigated. Results showed that there was almost no difference in the creep lives between the NiCr and NiCrA1 coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrA1 powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton＇s power law, εmin=Aσ^n, with the values of A=2.66×10^-16 MPa^-n·h^-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

关键词： Creep Coating θ projection method Minimum creep strainrate

危险预知训练模式结合密室逃脱教学在儿科急诊护士培训中的应用

在线全文

学校读者我要写书评

暂无评论

卫生职业教育 2025年第1期43卷 143-145页

作者：王珍朱杉华中科技大学同济医学院附属同济医院湖北武汉430030

目的探讨在儿科急诊护士培训中,危险预知训练模式结合密室逃脱教学的实践效果。方法选取湖北省武汉市某三甲医院2023年1—12月儿科急诊护士46人作为研究对象,随机分为对照组与研究组,分别实施常规培训模式、危险预知训练模式结合密室逃... 详细信息

目的探讨在儿科急诊护士培训中,危险预知训练模式结合密室逃脱教学的实践效果。方法选取湖北省武汉市某三甲医院2023年1—12月儿科急诊护士46人作为研究对象,随机分为对照组与研究组,分别实施常规培训模式、危险预知训练模式结合密室逃脱教学模式,对比两组考核成绩、应急能力、评判性思维能力与风险识别能力。结果研究组理论和急救技能考核成绩及应急能力、评判性思维能力、护理风险识别能力均优于对照组,差异有统计学意义(P<0.05)。结论危险预知训练模式结合密室逃脱教学应用于儿科急诊护士培训中效果较好,能有效提升护士的理论和急救技能水平及综合能力,值得推广。

关键词：危险预知训练模式密室逃脱教学模式儿科急诊护士

维普期刊数据库博看期刊

Predictive Control with Velocity Observer for Cushion Robot Based on PSO for Path Planning

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2020年第4期33卷 988-1011页

作者： SUN Ping shan Rui School of Information Science and Engineering Shenyang University of TechnologyShenyang 110870China

This paper proposes a novel model predictive control method with velocity estimation simultaneously constraining trajectory and velocity tracking errors for a cushion robot. The authors investigated a path planning method using improved particle swarm optimization(PSO) combined with Dijkstra’s algorithm and obtained a real-time desired optimal motion path for obstacle *** authors designed a velocity observer to estimate the unmeasurable speed, while the asymptotic stability of the observer error system was established. A predictive controller with error-constrained performance was derived by solving a quadratic programming problem with incremental control. Simulation and experimental results confirm the effectiveness of the proposed method and verify that the error constraints adopted in the cushion robot provide safe motion while avoiding obstacles.

关键词： robot Robot Velocity

New Proposals for Application of Terahertz Imaging Technique in Chinese Medicine

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Integrative Medicine 2022年第4期28卷 366-373页

作者： BAI shan-shan YANG Hua-yuan School of Acupuncture Moxibustion and Tuina Shanghai University of Traditional Chinese MedicineShanghai201203China

The rapid development of terahertz technology promotes the realization of various terahertz imaging *** technology features terahertz waves as good non-invasive illumination sources due to their high spectral resolution,penetration and *** terahertz imaging technique(TIT)has gradually been extended from the biomedical field to the field of Chinese medicine(CM),and it has become a powerful tool for seeking scientific evidence for CM theories with the use of modern science and *** paper reviews the current application of TITs in the field of CM research,and most importantly offers novel proposals for the application of TITs in CM research from the perspective of CM syndrome objectification and acupuncture research and cites existing reports as reference to the feasibility of these new proposals.

关键词： terahertz Chinese medicine syndrome objectification meridians acupuncture moxibustion new proposals

State and fate of the remaining tropical mountain glaciers in Australasia using satellite imagery

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第3期15卷 495-503页

作者： Bijeesh Kozhikkodan VEETTIL WANG shan-shan Department for Management of Science and Technology Development Ton Duc Thang University Faculty of Environment and Labour Safety Ton Duc Thang University Key Laboratory of Arid Climate Change and Reducing Disaster of Gansu Province & Key Open Laboratory of Arid Climate Change and Disaster Reduction of CMA Institute of Arid Meteorology CMA

Tropical glaciers are extremely sensitive to a warming climate. In this paper, the evolution of the remaining tropical glaciers in Australasia(Irian Jaya, Indonesia) during the period 1988-2015 was quantified. Landsat series images, a digital elevation model from SRTM, and previously published data were used. Estimated total glacier area in 1988, 1993, 1997 and 2004 was 3.85 km2±0.13 km2, 3.01 km2±0.08 km2, 2.49 km2±0.07 km2 and 1.725 km2 ±0.042 km2, respectively. Only 0.58 km2±0.016 km2 glacierized area remained in 2015 in Puncak Jaya, which is about 84.9% loss in just 27 years. If this rate continued, the remaining tropical glaciers in Australasia would disappear in the 2020 s. Timeseries analysis of climate variables showed significant positive trends in air temperature(0.009°C per year) and relative humidity(0.43% per year) but no considerable tendency was observed for precipitation. Warming climate together with mining activities would accelerate loss of glacier coverage in this region.

关键词： Glacier shrinkage Puncak Jaya Tropical glaciers Climate change

Buckling morphology of glassy nematic films with staggered director field

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2023年第11期44卷 1841-1852页

作者： shan XIA Linghui HE College of Civil Engineering Anhui Jianzhu UniversityHefei 230601China Department of Modern Mechanics and State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China

The photo-induced buckling of axially periodic glassy nematic films with alternating stripped director domains is explored by the F¨oppl-von K′arm′an plate theory along with a modified kinetics *** effects of domain widths on the critical light intensity as well as the buckling morphology are examined *** is found that in most cases the buckled film forms regularly aligned dimples and protrusions,but shows large scale bending perpendicular to the periodic axis if the widths of the stripes are nearly the *** addition,change in light intensity is shown to alter the wavenumber of the buckling *** results are expected helpful to the design of shape-shifting structures with glassy nematic films.

关键词： glassy nematic flm buckling morphology staggered director field

Empirical Likelihood Inference for a Partially Linear Errors-in-variables Model with Covariate Data Missing at Random

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2016年第2期32卷 305-318页

作者： shan-shan WANG Heng-jian CUI School of Economics and Management Beihang UniversityBeijing 100191China Beijing Key Laboratory of Emergency Support Simulation Technologies for City Operations Beijing 100191China School of Mathematical Sciences&:BCMIIS Capital Normal UniversityBeijing 100048China

The authors study the empirical likelihood method for partially linear errors-in-variables model with covariate data missing at random. Empirical likelihood ratios for the regression coeffidents and the baseline function are investigated, and the corresponding empirical log-likelihood ratios are proved to be asymptotically standard chi-squared, which can be used to construct confidence regions. The finite sample behavior of the proposed methods is evaluated by a simulation study which indicates that the proposed methods are comparable in terms of coverage probabilities and average length of confidence intervals. Finally, the Earthquake Magnitude dataset is used to illustrate our proposed method.

关键词： chi-square distribution confidence region coverage probability empirical likelihood partiallylinear model