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The purpose of this paper is to propose a new aerodynamic parameter estimation methodology based on neural network and output error method, while the output error method is improved based on particle swarm algorithm.

Firstly, the algorithm approximates the dynamic characteristics of aircraft based on feedforward neural network. Neural network is trained by extreme learning machine, and the trained network can predict the aircraft response at (k + 1)th instant given the measured flight data at kth instant. Secondly, particle swarm optimization is used to enhance the convergence of Levenberg–Marquardt (LM) algorithm, and the improved LM method is used to substitute for the Gauss Newton algorithm in output error method. Finally, the trained neural network is combined with the improved output error method to estimate aerodynamic derivatives.

Neither depending on the initial guess of the parameters to be estimated nor requiring numerical integration of the aircraft motion equation, the proposed algorithm can be used for unstable aircraft and is successfully applied to extract aerodynamic derivatives from both simulated and real flight data.

The proposed method requires iterative calculation and can only identify parameters offline.

The proposed method is successfully applied to estimate aircraft aerodynamic parameters and can also be used as a new algorithm for other optimization problems.

In this study, the output error method is improved to reduce the dependence on the initial value of parameters and expand its application scope. It is applied in aircraft aerodynamic parameter identification together with neural network.

Although officially ended in July 2020, China’s dispute about its non-market economy (NME) status at the World Trade Organization (WTO) is far from being resolved. The NME status enables China’s counterparts to disregard Chinese prices in antidumping proceedings and instead use the so-called surrogate country methodology. This paper aims to structure and analyze the complex debate, which emerged with the disputes China has filed against the European Union and the USA at the WTO, and therefore provide a point of reference for future analysis of and debates about China’s NME status.

The analysis is based on the existing academic literature on the topic and on the legal WTO-related documents (e.g. multilateral agreements, China’s Accession Protocol, legal findings of the WTO dispute panels).

Four different interpretations of the respective legal documents about China’s NME status are discussed and strong and weak aspects of these interpretations are pointed out. Also, several misunderstandings and mistakes appearing in the debate are clarified.

As the question of China’s position at the WTO and its NME status has not been resolved yet and some authors believe that China will pursue its case again once the WTO Appellate Body revives its functionality, the analysis of the debate can serve as a point of reference for the academic debate and the future research on this topic. Moreover, it offers an introduction to China’s NME position at the WTO for the newcomers to this topic.

Although China’s NME status has been much discussed, there is no literature review that would structure the debate and point out some of the (dis)advantages of the respective arguments and interpretations. Rather than adding to the large corpus of literature about the NME status, this study takes this corpus as the object of its analysis.