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21.
A new sensor for detecting ski bending and torsional deflection during an actual ski turn on the snow has been developed.
It consisted of bending and torsion sensors connected by light rigid beams. This structure was fixed to the upper surface
of a ski and passed through a tunnel in the central binding plate. The bending and torsion sensors were strain cells, designed
to reject strain orthogonal to the desired measurement direction. The calibration factor for each sensor was determined in
a jig, then the calibration of the overall sensor assembly was checked by static bending experiments and a free vibration
test. A data logger recorded the strain signals synchronously with other data such as the components of the earth’s magnetic
field measured by a sensor on the ski. The data set allowed reconstruction in software of the instantaneous shape, direction
and edge angle of the ski. The purpose of this paper is mainly to introduce the equipment used and methods developed. Tests
of the sensor performance are described. Results from a ski run on snow are presented to show how the various types of data
can be combined. A skilled ski athlete performed long turns with the ski at about 60 km/h on a groomed snow surface at Shiga
Kogen in Japan. The experiment on snow showed that the deformation of the ski was predominantly bending; torsional deflection,
although measurable, had only a small effect on the shape of the running edge. The ski edge adopted a symmetrical circular
bent shape with an unexpectedly small radius when on the outside, but was unconstrained, lightly loaded and nearly straight
when on the inside. 相似文献
22.
三田刚史 《徐州师范大学学报(哲学社会科学版)》2005,31(5):5-10
通过对自1922年9月至1925年11月在上海发行的《孤军》杂志上的论战,尤其是《经济政策讨论》的分析,可以看出留日中国学生如何看待马列主义和中国革命。该杂志的论者包括杜国庠、王学文、李希贤、史维焕、周佛海等,他们都师从东亚马克思主义先驱者河上肇教授。他们在讨论的过程中不一定接受共产国际对中国革命的见解与方针,而主张中国的社会主义革命为时尚早的论者占了论争的主导。但是,他们并不否定社会主义,反而将留日期间得到的知识加以消化,使它们成为分析中国现状的工具,用来探索走向社会主义的中国特有道路或中国独特的革命方略。 相似文献
23.
Background:The adhesion of monocytes to the endothelium following accumulation oflow-density lipoprotein(LDL) in subendothelial spaces is an important step in the development of intimal hyperplasia in arterially implanted vein grafts and atherosclerosis in both animals and humans.However.it iS not well known how serum factors affect the adhesion of monocytes.Methods:We have studied the efrect of fetal calf serum(FCS).which we considered a source of LDL.on the adhesion of monocytes to endothelial cells(Ecs)by using human monocytic THP-1 cells and both a monolayer of cultured bovine aortic endothelial cells(EC monoculture)and a co-culture with bovine aortic smooth muscle cells(EC-SMC co-culture).Results:It was found that the addition of FCS to the medium greatly affected the adhesion of THP-1 cells,and the higher the concentration of FCS in the medium,the greater the adhesion of THP-1 cells to endothelial cells.Adhesion of THP-1 cells to an EC-SMC co-culture Was approximately twofold greater than that to an EC monoculture,and after adhering to endothelial cells,many THP-1 cells transmigrated into the layer of smooth muscle cells.Conclusion:The results suggest that the elevation of the LDL(cholesterol)level in blood provides a favorable condition for the development of intimal hyperplasia and atherosclerosis by promoting the adhesion of monocytcs to the endothelium and their subsequent migration into subendothelial spaces. 相似文献
24.
While Honduras's post-1990s enrolment status has improved, no reports examine changes in status. We examined changes in enrolment patterns by analysing 1689 children's data using the true cohort method. We also analysed educational-development strategies/policies and project documentation. Grade-failure numbers did not improve over time because more children attended school, and no clear influence of strategies/policies and projects on educational quality was observed. Enrolment patterns were divided into graduation pattern with once-or-none repetition, and into dropout pattern after one-or-two years’ attendance. However, the more recent the school entrance year, the more often students continued attendance until graduation. Policy implications of these are discussed. 相似文献
25.
Mikio Miyazaki 《Educational Studies in Mathematics》2000,41(1):47-68
The purpose of this study is to establish levels from an inductive proof to an algebraic demonstration in lower secondary school mathematics. I propose that we can establish six levels of proof in lower secondary school mathematics as steps from an inductive proof to an algebraic demonstration on the basis of three axes (contents of proof, representation of proof, and students' thinking). To reach this conclusion, I firstly examine the meaning of demonstration in lower secondary school mathematics and proof in lower secondary school mathematics, and show the relationships between them. Secondly, I set out four basic levels of proof, as seen from two aspects (contents and representation of proof). Thirdly, I subdivide them into six levels from the third aspect of students' thinking. Finally, I illustrate my discussion with a 7th grader's activities.This revised version was published online in September 2005 with corrections to the Cover Date. 相似文献
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27.
Takeshi Miyakawa 《Educational Studies in Mathematics》2017,94(1):37-54
This paper reports the results of an international comparative study on the nature of proof to be taught in geometry. Proofs in French and Japanese lower secondary schools were explored by analyzing curricular documents: mathematics textbooks and national curricula. Analyses on the three aspects of proof—statement, proof, and theory—suggested by the notion of Mathematical Theorem showed differences in these aspects and also differences in the three functions of proof—justification, systematization, and communication—that are seemingly commonly performed in these countries. The results of analyses imply two major elements that form the nature of proof: (a) the nature of the geometrical theory that is chosen to teach and (b) the principal function of proof related to that theory. This paper suggests alternative approaches to teach proof and proving and shows that these approaches are deeply related to the way geometry is taught. 相似文献
28.
A featured microchip owning three big reservoirs and long turned geometry channel was designed to improve the detection limit of DNA fragments by using floating electrokinetic supercharging (FEKS) method. The novel design matches the FEKS preconcentration needs of a large sample volume introduction with electrokinetic injection (EKI), as well as long duration of isotachophoresis (ITP) process to enrich low concentration sample. In the curved channel [∼45.6 mm long between port 1 (P1) and the intersection point of two channels], EKI and ITP were performed while the side port 3 (P3) was electrically floated. The turn-induced band broadening with or without ITP process was investigated by a computer simulation (using CFD-ACE+ software) when the analytes traveling through the U-shaped geometry. It was found that the channel curvature determined the extent of band broadening, however, which could be effectively eliminated by the way of ITP. After the ITP-stacked zones passed the intersection point from P1, they were rapidly destacked for separation and detection from ITP to zone electrophoresis by using leading ions from P3. The FEKS carried on the novel chip successfully contributed to higher sensitivities of DNA fragments in comparison with our previous results realized on either a single channel or a cross microchip. The analysis of low concentration 50 bp DNA step ladders (0.23 μg∕ml after 1500-fold diluted) was achieved with normal UV detection at 260 nm. The obtained limit of detections (LODs) were on average 100 times better than using conventional pinched injection, down to several ng∕ml for individual DNA fragment. 相似文献
29.
Naoyuki Ebine Hoby Hasina Rafamantanantsoa Youichirou Nayuki Kunio Yamanaka Kouzou Tashima Takeshi Ono 《Journal of sports sciences》2013,31(5):391-397
To determine the daily energy requirements of professional soccer players during a competitive season, we measured total energy expenditure in seven players (age 22.1 - 1.9 years, height 1.75 - 0.05 m, mass 69.8 - 4.7 kg; mean - s ) using the doubly labelled water method. Energy intake was simultaneously estimated from 7 day self-report dietary records. Mean total energy expenditure and energy intake were 14.8 - 1.7 MJ · day -1 (3532 - 408 kcal· day -1 ) and 13.0 - 2.4 MJ · day -1 (3113 - 581 kcal· day -1 ), respectively. Although there was a significant difference between total energy expenditure and energy intake ( P ? 0.01), there was a strong relationship between the two ( r = 0.893, P ? 0.01). Basal metabolic rate and recommended energy allowance calculated from the Recommended Dietary Allowances for the Japanese were 7.0 - 0.3 MJ ·day -1 (1683 - 81 kcal· day -1 ) and 15.6 - 0.8 MJ · day -1 (3739 - 180 kcal· day -1 ), respectively. A physical activity level (total energy expenditure/ basal metabolic rate) of 2.11 - 0.30 indicated that, during the competitive season, professional soccer players undertake much routine physical activity, similar to that of competitive athletes during moderate training. Energy intake estimated using dietary records was under-reported, suggesting that its calculation from these data does not predict energy expenditure in soccer players. 相似文献
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