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Tungsten is an irreplaceable primary material and strategic resource for national economic development and modern national defense security. The endowment of tungsten ore resources in various countries is different; we should not only focus on the availability of tungsten ore itself but also the sustainability of its entire process from upstream supply to downstream industry demand. Analyzing the evolution of the supply and demand patterns of tungsten ore trade from the perspective of the industrial chain, identifying the key supply and demand subjects, and exploring the influencing factors of trade has become an important research topic. Therefore, we construct global tungsten trade networks based on the industrial chain, analyze its overall characteristics, explore critical trade supply and demand entities, and identify China's trade position. We got some meaningful results: (1) The global tungsten trade networks have prominent power-law distribution characteristics. The trend of trade globalization is evident, but the dominance is still in the hands of a few developed countries or developing countries with developed manufacturing industries. (2) In different parts of the tungsten industry chain, the impact of resource endowment, industrial technology level, and geographical location on the country's trade role is different. (3) China's position in the global tungsten resource industry chain and value chain is constantly improving, but there is still a risk of high-end technology being "stuck." This provides some suggestions for the systematic understanding of the evolution of the trade pattern of the tungsten industry chain and how countries occupy a dominant position in the game of tungsten resources. [ABSTRACT FROM AUTHOR]

Mineral resources are the basic materials for global economic development. Assessing mineral resource supply chain resilience is an important pillar of mineral resource supply chain stability management. The globality, heterogeneity and complexity of supply chain bring challenges to the resilience assessment of global mineral resource supply chain. To solve this problem, a method based on multi-region input-output model, network percolation model and econometric model is proposed, which is able to measure the resilience of global mineral resource supply chain and its influencing factors from the perspective of the whole system. The percolation phase transition is introduced to measure the critical state of global mineral resource supply chain system collapse facing external disruption. Using the proposed method, this paper conducts an empirical study on the evolution of global mineral resource supply chain resilience from 2005 to 2014. The results show that the resilience of global mineral resource supply chain declined by 39.6% in 2005-2014. Most of the critical links that caused the collapse of the global mineral resource supply chain network are the manufacturing sector and its upstream and downstream sectors. The structure of supply chain network plays a key role in network resilience. Increasing the number of linkages in upstream and downstream could improve network resilience, but the increase of linkage strength would deteriorate network resilience. [ABSTRACT FROM AUTHOR]

The lifetime data collected from the field are usually heavily censored, in which case, getting an accurate reliability evaluation based on heavily censored data is challenging. For heavily Type‐II censored data, the parameters estimation bias of traditional methods (i.e., maximum likelihood estimation (MLE) and least squares estimation (LSE)) are still large, and Bayesian methods are hard to specify the priors in practice. Therefore, considering the existing range of shape parameter for Weibull distribution, this study proposes two novel parameter estimation methods, the three‐step MLE method and the hybrid estimation method. For the three‐step MLE method, the initial estimates of shape and scale parameters are first respectively derived using MLE, then are updated by the single parameter MLE method with the range constraint of shape parameter. For the hybrid estimation method, the shape parameter is estimated by the LSE method with the existing range constraint of shape parameter, then the scale parameter estimate can be obtained by MLE. On this basis, two numerical examples are performed to demonstrate the consistency and effectiveness of the proposed methods. Finally, a case study on turbine engines is given to verify the effectiveness and applicability of the proposed methods. [ABSTRACT FROM AUTHOR]