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1.
J. T. Sun W. Wang P. Zhang S. G. Zhao 《Journal of Macromolecular Science: Physics》2013,52(8):1658-1667
The hardness (H) and resilience (R) of rubber vulcanizates were combined together in this paper, named as hardness–resilience product (H4R), and its relationship with the Akron abrasion loss was investigated using various styrene-butadiene rubber (SBR) vulcanizates possessing specific hardness and resilience characteristics as samples. For the unfilled SBR vulcanizates with different chain microstructure, possessing high elastic resilience and low hardness, the results showed that their Akron abrasion loss had a good linear relationship with the log(H4100R). This linear relationship also occurred when these SBRs were filled with 50 phr carbon black. For two particular types of SBR, after being filled with different fractions of carbon black and aged for different times, all their Akron abrasion losses (including unaged, aged for 24 h, and aged for 48 h) also had a good linear relationship with the log(H4100R). However, this linear relationship weakened for one of the SBRs after being aged for 48 h. In the high H4R region (the carbon black fractions being 60 and 70 phr), the data obviously deviated from the fitting curve due to the high hardness of the aged vulcanizates. However, after being filled with 50 phr of various kinds of carbon blacks, the relationships between abrasion loss and log(H4100R) were also approximately linear, with the correlation coefficient of the fitting curves being 0.99966 and 0.99878, respectively, for the two types of SBR. 相似文献
2.
This paper proposes a dynamic cascade model to investigate the systemic risk posed by sector-level industries within the U.S. inter-industry network. We then use this model to study the effect of the disruptions presented by Covid-19 on the U.S. economy. We construct a weighted digraph G = (V,E,W) using the industry-by-industry total requirements table for 2018, provided by the Bureau of Economic Analysis (BEA). We impose an initial shock that disrupts the production capacity of one or more industries, and we calculate the propagation of production shortages with a modified Cobb–Douglas production function. For the Covid-19 case, we model the initial shock based on the loss of labor between March and April 2020 as reported by the Bureau of Labor Statistics (BLS). The industries within the network are assigned a resilience that determines the ability of an industry to absorb input losses, such that if the rate of input loss exceeds the resilience, the industry fails, and its outputs go to zero. We observed a critical resilience, such that, below this critical value, the network experienced a catastrophic cascade resulting in total network collapse. Lastly, we model the economic recovery from June 2020 through March 2021 using BLS data. 相似文献
3.
根据能量原理,引入大挠度Von-Karman方程,求解了应力不连续简支板的屈曲问题,得到了临界载荷和临界应力计算系数. 相似文献
4.
Vladimir I. Levenshtein 《Designs, Codes and Cryptography》1997,12(2):131-160
A system of (Boolean) functions in
variables is called randomized if the functions preserve the property of their variables to be independent and uniformly distributed random variables. Such a system is referred to as
-resilient if for any substitution of constants for any
variables, where 0 i t, the derived system of functions in
variables will be also randomized. We investigate the problem of finding the maximum number
of functions in
variables of which any
form a
-resilient system. This problem is reduced to the minimization of the size of certain combinatorial designs, which we call split orthogonal arrays. We extend some results of design and coding theory, in particular, a duality in bounding the optimal sizes of codes and designs, in order to obtain upper and lower bounds on
. In some cases, these bounds turn out to be very tight. In particular, for some infinite subsequences of integers
they allow us to prove that
,
,
,
,
. We also find a connection of the problem considered with the construction of unequal-error-protection codes and superimposed codes for multiple access in the Hamming channel. 相似文献
5.
本文利用统计计量学方法对山西省农民家庭消费水平和消费结构的变化及原因进行了实证分析。建立了山西省农民人均消费的消费函数和山西省农民总消费支出与食品、衣着、住房、日用品、燃料及文化生活服务支出的关系模型，并通过模型分析解释了农民的消费结构，也为决策者提供一些有效的参考资料。 相似文献
6.
针对作战系统网络单元的异质性以及各个单元之间的交互联系,本文建立了包含作战和保障单元的三层装备保障多层耦合网络,将作战系统体系结构分为打击敌方目标的作战子系统、对我方毁伤装备和机构进行维修的保障子系统、对我方装备和机构进行物资供应的保障子系统。同时给出了基于网络拓扑结构和节点间信息传递类型的重要度评估方法。其次,基于负载-容量模型研究网络的级联失效传递过程,通过节点重要度进行蓄意攻击,判断负载再分配后的网络是否失效。然后,为了增强多层耦合网络韧性,基于剩余杀伤链数量,提出剩余可分配任务量韧性策略,缓解级联失效对整个网络的影响。最后,通过对不同攻击方式下多层耦合网络韧性进行仿真,验证了基于重要度进行攻击的效果明显优于随机攻击;对实施与未实施剩余可分配任务量韧性策略时的多层耦合网络韧性进行仿真,结果表明该策略能大幅提升网络韧性,减少级联失效的影响,增加网络在失效过程中的平均性能。 相似文献
7.
Infrared spectroscopy measurements were performed on Lysozyme aqueous solutions also in the presence of PolyEthylene Glycol (PEG 400) as a function of an increasing temperature from T = 27 °C to 90 °C, and, successively in sequence, by decreasing temperatures from T = 90 °C to 27 °C. Data were analyzed by evaluating the spectral difference with respect to the initial spectrum collected at 27 °C. This procedure allows to quantitatively evaluate the thermal restraint related to the thermal scan from T = 27 °C to 90 °C, as well as to introduce a spectral resilience concerning the entire increasing and decreasing thermal paths which allow to highlight the bioprotectant effectiveness of low molecular weight PEG. In particular, the main purpose of the present work is to highlight the effects of a thermal treatment on a mixture of Lysozyme/water and of Lysozyme/water/PEG 400 during an increasing temperature scan, and then after a successive decreasing temperature scan, in order to highlight the bioprotectant role of PEG 400. On that score, an evaluation of the spectral distances of the registered spectra as a function of increasing and decreasing temperatures has been performed and analyzed. 相似文献
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9.
RAM RANJAN 《Natural Resource Modeling》2013,26(2):237-258
Abstract. Ensuring drought resilience for farmers is an important policy concern. Yet, a quantitative treatment of the concept of drought resilience has been lacking in the literature. This paper designs a mathematical model of drought resilience to assess farmers’ survival strategies when faced with the prospect of repeated droughts. A key distinction is being made here between consecutive droughts and one‐off droughts, as it is the former, which is of most concern to farmers as well as policy makers. The mathematical model is generalized to incorporate the possibility of more than one set of a certain number of consecutive droughts occurring in the future. Findings indicate varying implications for groundwater sustainability when resilience outcomes are directly linked to the length of a farmer's drought planning horizon as well as to the planned minimum consumption during drought years. 相似文献
10.