Summary Bio‐oil is a promising alternative energy source to crude oil for broad application prospects. Bio‐oil can help us avoid over‐reliance on petroleum resources and significantly reduce pollutants and greenhouse gas emissions, improve environment conditions, and protect ecological systems. However, bio‐oil applications have been impeded because of limited technologies, and poor bio‐oil quality has posed a great challenge. As such, considerable research efforts have been made for realizing its potential application value. Scientific and technical advancements on methods of bio‐oil quality improvement to date are reviewed, with an emphasis on advantages and disadvantages of each method. It also points out barriers and gives some recommendations to enhance bio‐oil combustion performance in the future. Copyright © 2017 John Wiley & Sons, Ltd.

The spatial pattern and evolution of urban system have been hot research issues in the field of urban research. In this paper, the network analysis method based on the gravity model and the related measurements were used to reveal the properties of the spatial pattern and evolution of the urban system in the HRB (Huaihe River Basin) of China. The findings of this study are as follows: During the period from 2006 to 2014, the economic contact between the HRB cities has been strengthened, but the differences between cities have been expanding. In general, the HRB cities have not yet formed a close network structure, and a trend of economic integration has not been found. This paper expresses the spatial pattern and evolution of urban system in an intuitive way and helps to explain the evolution mechanism of urban system. The method was confirmed by empirical research. Because of the operational and visual expression, this method has broad application prospects in the urban system research.

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A collision model has been developed for nonlinear dynamic finite element analysis on an LNG ship and a crushable ice using commercial code DYTRAN. In this modeling, a global LNG ship model has been employed as a deformable body which follows the elastic-plastic constitutive model, and an ice floe has been modeled as a crushable body including material failure. The deformation and failure of the ship structure and the ice as well as the contact force at the contact area between the ship and the ice have been determined from collision simulations. For most ship-ice interaction scenarios, the ice load applied to the ship can be considered as a quasi-static load. The loading capacity of LNG ship hull structure has been investigated applying static ice loads to a local model, which is a whole compartment of a cargo tank in the ship structure including five components such as the side shell plating, longitudinal stiffeners, stringers, web frames, and inner hull. For each ship and ice interaction scenario, loading cases at five varying locations in the local model have been investigated. Numerical results show that different loading location cases cause the structure failure at different components. FE results also indicate that large plastic deformation and buckling failure modes are found in different components of the hull structure. Finally, acceptance criteria and the complete procedure have been developed for the strength evaluation of hull structure in LNG carriers under ice loads.

Abstract:In this paper, an automatic sparse pruning endmember extraction algorithm with a combined minimum volume and deviation constraint (SPEEVD) is proposed. The proposed algorithm can adaptively determine the number of endmembers through a sparse pruning method and, at the same time, can weaken the noise interference by a minimum volume and deviation constraint. A non-negative matrix factorization solution based on the projection gradient is mathematically applied to solve the combined constrained optimization problem, which makes sure that the convergence is steady and robust. Experiments were carried out on both simulated data sets and real AVIRIS data sets. The experimental results indicate that the proposed method does not require a predetermined endmember number, but it still manifests an improvement in both the root-mean-square error (RMSE) and the endmember spectra, compared to the other state-of-the-art methods, most of which need an accurate pre-estimation of endmember number.

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