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盾构隧道壁后注浆是控制隧道沉降与地表塌方的重要措施,在实际工程中,存在壁后注浆的实际效果难以控制等技术难题,缺乏切实可靠的检测手段,针对这一问题,本文自主创新开发了上海隧道壁后可视化雷达检测技术,适用于隧道壁后注浆质量检测控制.该方法使用方便,开发了集资料处理及成果智能解释于一体的专用雷达软件系统,可以有效进行壁后注浆风险控制. 相似文献
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本研究利用低温扫描隧道显微镜研究了吸附在超导体表面上的磁性杂质诱导的束缚态。通过提高扫描隧道谱的能量分辨率,可以观察到对应于不同角动量散射通道的多重束缚态。该工作提供了一种探测单个自旋态以及研究磁性与超导相互竞争等的灵敏实验手段。 相似文献
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2000年以来,罗马被誉为全世界最伟大的帝国之都,因为它的修建运用了天才的工程原理,而它在地质方面也得天独厚。目前,一支由岩洞科学家组成的团队,准备到罗马市地下的世界去探索一番。他们进入了一座有2000多年历史的巨大隧道迷宫,这些古代洞穴里藏着罗马工程师如何建造这座不朽城市的秘密。一位参与考察的岩洞科学家说:"这些是鹤嘴锄留下的痕迹,这里是罗马人挖隧道的地方,也是罗马人采石的地方。这种石头由火山灰构成,是一种很耐用的材料,很适合用来修建建筑物。这些火山灰来自罗马附近的火山。"罗马位于一条山谷里,紧挨着 相似文献
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科学理论如何能够被我们判定其真或伪,成真的概率有多大,是科学哲学认识论的基本问题之一。当代英国哲学家理查德·斯温伯恩对科学理论的成真概率进行了逻辑演绎。他提出,科学理论的成真概率包括两个方面,其一是经验成真概率;其二是先验成真概率。前者依靠科学理论的"解释力";后者则依靠科学理论预设条件的"简单性"。两者一并构成了我们判定科学理论成真概率的原理。斯温伯恩关于科学理论成真概率的原理不仅适用于非生命事件的解释领域,而且也适用于有生命的人格性事件的解释领域。 相似文献
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康德以其先验哲学的视角指出以“作用因”为其先验根据的牛顿力学原理在解释生命之独特性时是不充分的。在对传统目的论思想进行批判性改造的基础上,他提出了把目的论与机械论结合起来的生命科学方法论,由康德倡导的方法论对生命科学产生了深刻的影响。 相似文献
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最凉快的汽车,这辆颇具创意的甲壳虫不知是出自哪位能人之手,不用空调和天窗都绝对的盗塞丕婪,下雨时怎么开呢?一只手开车.一只手打伞?…… 相似文献
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HEMS深井降温系统研发及热害控制对策 总被引:2,自引:0,他引:2
深井高温热害是深部煤炭资源开采过程中的严重灾害,高温不仅影响了围岩的力学性质,而且严重影响矿井生产安全。本研究针对国内外矿井降温技术存在的问题,提出了以矿井涌水作为冷源的深井开采高温热害控制HEMS(High Temperature Exchange Machinery System)技术,利用提取出的冷量与工作面高温空气进行换热作用,降低工作面的环境温度及湿度。该技术结合夹河矿深井降温工程,建成了国内第一个控制深井热害的深部科学与工程实验室(DUSEL)。系统运行结果表明,工作面温度降低4-6℃,最高温度控制在28—290℃以内,相对湿度降低5%-10%,极大改善了井下工作环境,热害控制效果显著,具有广阔的推广应用前景。 相似文献
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技术创新的域、势、能 总被引:1,自引:0,他引:1
技术创新是特定域内的一种科学和技术的涌现,这种涌现取决于技术创新所在域内的势与能,域是创新的根基,具有边界有形性、区隔性和分层性等特征;势是域内创新的事物充满张力的局态,体现为吸附性和凝聚性;能则是域内创新的事物所具有的潜在能量与动力,体现为动力本源性和持续性。国家或地区的技术创新通过一定的域,形成一定的势,对外吸附外在资源,对内聚集资源,最终以持续的技术创新来促进国家或地区的经济、文化、政治的跨越性发展。 相似文献
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The objective of this paper is to develop the maximum likelihood approach
for analyzing a finite mixture of structural equation models with missing data that are
missing at random. A Monte Carlo EM algorithm is proposed for obtaining the maximum
likelihood estimates. A well-known statistic in model comparison, namely the Bayesian
Information Criterion (BIC), is used for model comparison. With the presence of missing
data, the computation of the observed-data likelihood function value involved in the BIC
is not straightforward. A procedure based on path sampling is developed to compute this
function value. It is shown by means of simulation studies that ignoring the incomplete
data with missing entries gives less accurate ML estimates. An illustrative real example is
also presented. 相似文献
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Clustering the rows and columns of a contingency table 总被引:3,自引:2,他引:1
Michael J. Greenacre 《Journal of Classification》1988,5(1):39-51
A number of ways of investigating heterogeneity in a two-way contingency table are reviewed. In particular, we consider chi-square decompositions of the Pearson chi-square statistic with respect to the nodes of a hierarchical clustering of the rows and/or the columns of the table. A cut-off point which indicates significant clustering may be defined on the binary trees associated with the respective row and column cluster analyses. This approach provides a simple graphical procedure which is useful in interpreting a significant chi-square statistic of a contingency table.The author gratefully acknowledges the constructive comments of the referees and the editor. 相似文献
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Vladimir G. Red'ko 《Foundations of Science》2000,5(3):323-338
The main problem discussed in this paper is: “Why and how did animal cognition abilities arise?” It is argued that investigations of the evolution of animal cognition abilities are very important from an epistemological point of view. A new direction for interdisciplinary researches – the creation and development of the theory of human logic origin – is proposed. The approaches to the origination of such a theory (mathematical models of ``intelligent invention'' of biological evolution, the cybernetic schemes of evolutionary progress and purposeful adaptive behavior) as well as potential interdisciplinary links of the theory are described and analyzed. 相似文献
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Single linkage clusters on a set of points are the maximal connected sets in a graph constructed by connecting all points
closer than a given threshold distance. The complete set of single linkage clusters is obtained from all the graphs constructed
using different threshold distances. The set of clusters forms a hierarchical tree, in which each non-singleton cluster divides
into two or more subclusters; the runt size for each single linkage cluster is the number of points in its smallest subcluster.
The maximum runt size over all single linkage clusters is our proposed test statistic for assessing multimodality. We give
significance levels of the test for two null hypotheses, and consider its power against some bimodal alternatives.
Research partially supported by NSF Grant No. DMS-8617919. 相似文献
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Sampo V. Paunonen 《Journal of Classification》1984,1(1):125-131
Analytic procedures for classifying objects are commonly based on the product-moment correlation as a measure of object similarity. This statistic, however, generally does not represent an invariant index of similarity between two objects if they are measured along different bipolar variables where the direction of measurement for each variable is arbitrary. A computer simulation study compared Cohen's (1969) proposed solution to the problem, the invariant similarity coefficientr
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, with the mean product-moment correlation based on all possible changes in the measurement direction of individual variables within a profile of scores. The empirical observation thatr
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approaches the mean product-moment correlation with increases in the number of scores in the profiles was interpreted as encouragement for the use ofr
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in classification research. Some cautions regarding its application were noted.This research was supported by the Social Sciences and Humanities Research Council of Canada, Grant no. 410-83-0633, and by the University of Toronto. 相似文献