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891.

针对当前地下爆炸物理模型实验无法模拟大当量地下爆炸抛掷弹坑和疏松鼓包现象的难题,基于相似理论,采用地下爆炸效应真空室模型实验方法,研制了考虑重力影响的大当量地下爆炸效应模拟实验装置。整套装置由容器罐体、快开门密闭机构、爆源系统、真空泵组、量测控制系统等组成,提出的新型爆源模拟装置可以实现精确起爆控制。该装置可模拟0.1~100 kt TNT、埋深20~400 m范围内不同比尺的地下核爆炸成坑和隆起实验,同时也能够模拟不同装药配置方案、不同地质条件下的大当量地下浅埋化爆抛掷实验。典型的核爆抛掷成坑模型实验结果表明,装置实验参数精确可调,实验过程可控,实验结果可信,为钻地核武器地下爆炸毁伤效应分析和大型工程爆破效果预测预报提供了实验室模拟和科学研究设备,填补了爆炸离心机无法模拟大当量地下爆炸抛掷成坑效应的空白。

  相似文献   
892.
在长期的工程流体力学教学过程中,发现学生对这门课普遍存在畏难情绪,对复杂的理论知识掌握困难.考虑到工程流体力学的研究方法分为理论分析方法,实验方法和数值方法,而其中数值方法在传统教学中应用的较少,所以试图通过适当增加数值方法的应用来改善教学效果.随着本科生对计算机应用能力的增强以及知识面的逐渐扩展,本文提出增加结合专业背景,理论知识及软件应用的综合案例以满足当前课程及学生发展的需求.  相似文献   
893.
Economic growth and human activities challenge the regional harmony of the economy and environment. Based on an evaluation of ecological carrying capacity (ECC), we have constructed a three‐dimensional trade‐off model for socially harmonious development for the Sichuan and Yunnan regions in southwest China. The results demonstrate that there is a continuous increase in socioeconomic coordination (SEC; slope > 0.23) and a change in the ECC in the study area, characterized by subtle fluctuations from 2000 through 2008. This was primarily due to the loss of resource and environment carrying capacity wiping out the profits of SEC. Significant government aid during the postdisaster reconstruction and more attention being paid to the environment in policy resulted in a faster increase in ECC (slope > 0.38) from 2008 to 2016. Based on this trade‐off model, managers could deeply understand the relationship between resources, the economy, and ecology. Summary for Managers
  • Ecological environment protection is increasingly crucial in Sichuan and Yunnan regions as they feel the effects of climate change and human activities.
  • The three‐dimensional trade‐off model measuring socially coordinated development is a modified multiobjective, decision‐making model.
  • Based on this trade‐off model, managers could, understand the relationship between resources, the economy, and ecology.
  • It can help manage our environmental assets and plan ecological conservation, to ensure that the environment maintains its capacity to serve the societal development.
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894.
The methodological procedures employed both for serving investigations in the field of micellar enzymology and developed directly in micellar enzymology and being of general significance, such as an estimation of molecular masses and sizes of biocatalysts, titration of active sites of enzymes, chemical modification of proteins (enzymes), conjugation and nanogranulation, are reviewed. Potentialities of using and informativity of various techniques are analyzed.  相似文献   
895.
 The article analyses the scope and limitations of quality systems for research centres in the light of the problems involved, foreseen advantages, and growing need created in the context of the globalisation phenomenon. Some propositions are put forward concerning the development of possible quality assurance strategies for research activities. Received: 30 June 1999 / Accepted: 24 September 1999  相似文献   
896.
We describe the spectral properties of underdoped cuprates as resulting from a momentum-dependent pseudogap in the normal-state spectrum. Such a model accounts, within a BCS approach, for the doping dependence of the critical temperature and for the two-parameter leading-edge shift observed in the cuprates. By introducing a phenomenological temperature dependence of the pseudogap, which finds a natural interpretation within the stripe quantum-critical-point scenario for high- superconductors, we reproduce also the bifurcation near optimum doping. Finally, we briefly discuss the different role of the gap and the pseudogap in determining the spectral and thermodynamical properties of the model at low temperatures. Received 17 February 2000  相似文献   
897.
Using a unique data set containing about 15.06 million truck transportation records in five months, we investigate the highway freight transportation diversity of 338 Chinese cities based on the truck transportation probability pij from one city to another. The transportation probabilities are calculated from the radiation model based on the geographic distance and its cost-based version based on the driving distance as the proxy of cost. For each model, we consider both the population and the gross domestic product (GDP), and find quantitatively very similar results. We find that the transportation probabilities have nice power-law tails with the tail exponents close to 0.5 for all the models. The two transportation probabilities in each model fall around the diagonal pij=pji but are often not the same. In addition, the corresponding transportation probabilities calculated from the raw radiation model and the cost-based radiation model also fluctuate around the diagonal pijgeo=pijcost. We calculate four sets of highway truck transportation diversity according to the four sets of transportation probabilities that are found to be close to each other for each city pair. It is found that the population, the gross domestic product, the in-flux, and the out-flux scale as power laws with respect to the transportation diversity in the raw and cost-based radiation models. It implies that a more developed city usually has higher diversity in highway truck transportation, which reflects the fact that a more developed city usually has a more diverse economic structure.  相似文献   
898.
 The design and the specifications of a prototype instrument for the electron gas version of secondary neutral mass spectrometry SNMS which will optionally enable measurements with X-ray induced photoelectron spectroscopy XPS, too, are described. By operating the SNMS plasma inside an ultra high vacuum vessel interfering signals from residual gas species are reduced to the level of the mass independent background. The influence of varying angular distributions of sputter-ejected neutrals at low ion energies for sample bombardment can be widely reduced by an oblique take-off for the postionized particles. First examples of SNMS-studies with the new system reveal a detection power well below 1 ppm. Analytically difficult elements as C or O become quantitatively detectable down to a level of several 10 ppm.  相似文献   
899.
结合化学课程的历史和现实需求,从多角度阐述了化学课程的全面育人价值,分析了《义务教育化学课程标准(2022年版)》中核心素养凝练的思路;提出了核心素养各要素的内涵和外延,梳理了初、高中学段2个核心素养体系之间的关系;探讨了基于核心素养的化学课程目标及化学学业质量标准体系建构的特点及应用。  相似文献   
900.
王奇峰 《化学教育》2022,43(6):116-119
研究生教育是高等教育中的重要内容,其存在的矛盾问题不容小觑。总结了研究生教育和学习过程中存在的4类矛盾,揭示了矛盾存在的原因,并结合自身经验提出了解决矛盾的方法。  相似文献   
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