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11.
许文 《新疆职业大学学报》2008,16(3):70-72
本文对卷取机恒张力控制的原理进行分析,利用磁粉离合器的激磁电流与转矩成线性关系这一特性,设计了一闭环张力控制系统。 相似文献
12.
王彤 《洛阳工业高等专科学校学报》2008,18(1)
采用人工裂纹试样的方法,模拟压力容器涂刷油漆防腐层的状况进行磁粉探伤,得出了油漆防腐层厚度与裂纹检出灵敏度的定量关系;结合CVDA<压力容器缺陷评定>规范,探讨了试验方法对一般在役压力容器带有油漆的情况下进行磁粉探伤检验的可行性.研究表明:采用交流磁化法进行探伤,当漆层厚度小于250 μm时灵敏度影响较小,同时亦表示不宜使用直流磁化方法.该结论对承受低应力工况条件下的压力容器安全质量检验和评估有重要参考价值. 相似文献
13.
INTRODUCTION Veselago (1968) showed that if both the permit- tivity ε and the magnetic permeability μ of a material are negative, the propagation direction of an elec- tromagnetic (EM) wave will be opposite to its energy flow direction. Such media are called left-handed materials (LHMs) since the electric field E, magnetic field H, and wave vector k in these media form a left-hand triplet of vectors, instead of a right-hand triplet observed in conventional materials. For a long time, … 相似文献
14.
介绍了漏磁检测的基本原理,分析了管道缺陷的漏磁信号与缺陷几何参数的关系.应用BP神经网络进行了管道缺陷参数的定量识别,识别结果的误差小于10%,完全满足实际检测的要求. 相似文献
15.
在大学物理电磁学的教学中，电场的旋度一向被关注较少．然而，要揭示电场和磁场的内在联系，必须对电场的旋度加以论述． 相似文献
16.
The phase transition characteristics of the prepared Ni46Mn35Ga19 single crystal have been systematically investigated by measuring resistance, strain, heat flow, and ac magnetic susceptibility. The experimental results indicate that both magnetic transition and martensitic transformation occurred simultaneously and the corresponding transition temperature was about 356 K. Meanwhile, the prepared single crystal also exhibited spontaneous and magnetic-field-enhanced two-way thermal shape memory effect with the strains up to -0.89% and -1.90% with and without a magnetic field of 1.6 T, respectively. The possible mechanism of the large spontaneous and magnetic enhanced deformation were analyzed based on the phase transition characteristics of Ni46Mn35Ga19 single crystal and the preferential orientation of martensitic variants. 相似文献
17.
Magnetic cell sorting and flow cytometry sorting methods for the isolation and function analysis of mouse CD4＋ CD25＋ Treg cells 总被引：5，自引：0，他引：5
Hang Yan Chen-guang Ding Pu-xun Tian Guan-qun Ge Zhan-kui Jin Li-ning Jia Xiao-ming Ding Xiao-ming Pan Wu-jun Xue 《Journal of Zhejiang University. Science. B》2009,10(12):928-932
Objective: In this paper we compared the two methods of cell sorting (magnetic cell sorting and flow cytometry sorting) for the isolation and function analysis of mouse CD4~+ CD25~+ regulatory T (Treg) cells, in order to inform further studies in Treg cell function. Methods: We separately used magnetic cell sorting and flow cytometry sorting to identify CD4~+ CD25~+ Treg cells. After magnetic cell separation, we further used flow cytometry to analyze the purity of CD4~+ CD25~+ Treg cells, trypan blue staining to detect cell viability, and propidium iodide (PI) staining to assess the cell viability. We detected the immune inhibition of CD4~+ CD25~+ Treg cells in the in vitro proliferation experiments. Results: The results showed that compared to flow cytometry sorting, magnetic cell sorting took more time and effort, but fewer live cells were obtained than with flow cytometry sorting. The CD4~+ CD25~+ Treg cells, however, obtained with both methods have similar immunosuppressive capacities. Conclusion: The result suggests that both methods can be used in isolating CD4~+ CD25~+ Treg cells, and one can select the best method according to specific needs and availability of the methodologies. 相似文献
18.
Thigh muscle volume is a useful determinant of functional fitness. However, anthropometric prediction of muscle content is influenced by the variability of adipose tissue accumulation. The aims of this study were to predict thigh muscle and adipose tissue volumes from anthropometry and to assess the validity of the method by examining the various components of the measurements and the assumptions involved. The 19 participants (9 men, 10 women; age 23-49 years) varied in adiposity. They all underwent magnetic resonance imaging (MRI) of the upper leg and the eight men and two women with the lowest adiposity underwent detailed anthropometry involving girths and skinfolds. Using MRI as the reference method, muscle volume was predicted from anthropometry using a circular concentric model, and the assumptions inherent in the method were tested further using the MRI data alone. Muscle volume was best predicted by anthropometry in the 10 leanest participants using a five-slice truncated cone model that overestimated the mean MRI value by 30% ( R 2 = 0.95; standard error of estimate = 288 cm 3 ; P ? 0.001). A single skinfold plus girth measurement at the mid-thigh almost matched its predictive ability, but with an increased bias. Measurements of leg circumference by means of the two techniques agreed well. The assumption of a circular cross-section was valid. In contrast, the agreement between skinfold thickness measured by caliper and superficial adipose tissue thickness by MRI was poor, contributing to the scatter of fat and lean area comparisons. An anterior skinfold thickness measurement underestimated the area of superficial adipose tissue at that level, particularly at the most proximal and distal sites. Although these limitations increase the uncertainties of muscle volume determination by anthropometry, they do not prevent its valid prediction in leaner individuals. The prediction of superficial adipose tissue was poorer. 相似文献
19.
R.J. Yquel L.M. Arsac E. Thiaudiere P. Canioni G. Manier 《Journal of sports sciences》2013,31(5):427-437
In this study, we examined the effect of creatine ingestion on muscle power output, muscle phosphocreatine resynthesis, inorganic phosphate and pH during repeated brief bouts of maximal exercise. Nine healthy males performed maximal plantar flexion before and after creatine ingestion (20 g ·day -1 for 6 days). The experimental protocol consisted of five 8 s bouts (bouts 1-5) interspersed with 30 s recovery, followed by bouts 6 (8 s) and 7 (16 s) separated by 1 and 2 min, respectively. Muscle phosphocreatine, inorganic phosphate and pH were estimated every 16 s by 31 P magnetic resonance spectroscopy. After creatine ingestion, muscle power output increased by ~5% ( P ? 0.05) from bouts 3 to 7 and muscle phosphocreatine resynthesis increased ( P ? 0.05) during 10 min recovery. The higher phosphocreatine concentration observed after only 30 s of recovery was accompanied by lower inorganic phosphate accumulation and higher pH. Strong correlations were found between exercise power restoration and the corresponding pre-exercise phosphocreatine and inorganic phosphate concentrations and muscle pH after creatine ingestion. The better maintenance of muscle power output observed after creatine ingestion was attributed to a higher rate of phosphocreatine resynthesis, lower accumulation of inorganic phosphate and higher pH. 相似文献
20.
Stephan Sorichter Johannes Mair Arnold Koller Erich Muller Christian Kremser Werner Judmaier 《Journal of sports sciences》2013,31(9):687-691
The aim of this study was to examine the relationship between myosin heavy chain (MHC) release as a specific marker of slow-twitch muscle fibre breakdown and magnetic resonance imaging (MRI) of skeletal muscle injury after eccentric exercise. The effects of a single series of 70 high-intensity eccentric contractions of the quadriceps femoris muscle group (single leg) on plasma concentrations of creatine kinase and MHC fragments were assessed in 10 young male sport education trainees before and 1 and 4 days after exercise. To visualize muscle injury, MRI of the loaded thigh was performed before and 4 days after the eccentric exercise. All participants recorded an increase ( P ? 0.05) in creatine kinase after exercise. In five participants, T2 signal intensity was unchanged post-exercise compared with pre-exercise and MHC plasma concentration was normal; however, they showed an increase ( P ? 0.05) in creatine kinase after exercise. For the remaining five participants, there was an increase in T2 signal intensity of the loaded vastus intermedius and vastus lateralis. These changes in MRI were accompanied by an increase in MHC plasma concentration ( P ? 0.01) as well as an increase in creatine kinase ( P ? 0.01). We suggest that changes in MRI T2 signal intensity after muscle damage induced by eccentric exercise are closely related to damage to structurally bound contractile filaments of some muscle fibres. Additionally, MHC plasma release indicates that this damage affects not only fast-twitch fibres but also some slow-twitch fibres. 相似文献