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The purpose of this paper is to reveal a symbol – “however” that authors are very interested in, but few research studies pay attention to the existing literature. The authors aim to further insight its function.

In this research, the authors selected 3,329 valid comments on articles published in the British Medical Journal (BMJ) from 2015 to 2020 as the research objects. The authors showed the length distribution of reviewers' comments. In what follows, the authors analyzed the general distribution of words in comments and reviewer comments’ position to understand reviewers' comments qualitatively in word dimension. Specially, the authors analyzed functions of “however” and “but”, words that authors are most concerned with. In addition, the authors also discussed some factors, which may be related to “however,” that reflect reviewers' praise through regression analysis.

The authors found that there are marked differences in the length of reviewers' comments under different review rounds. By mapping the reviewers' comments to different sections, the authors found that reviewers are deeply concerned to methods section. Adjectives and adverbs in comments written in different sections of the manuscripts also have different characteristics. The authors tried to interpret the turning function of “however” in scientific communication. Its frequency of use is related to reviewers' identities, specifically academic status. More precisely, junior researchers use “however” in praise more frequently than senior researchers do.

The linguistic feature and function of “however” and “but” in the reviewers' comments of the rejected manuscripts may be different from accepted papers and also worth exploring. Regrettably, the authors cannot obtain the peer review comments of rejected manuscripts. This point may limit the conclusion of the investigation of this article.

Overall, the survey results revealed some language features of reviewers' comments, which could provide a basis of future endeavors for many reviewers in open peer review (OPR) field. Specially, the authors also put forward an interesting symbol to examine the review comments, “however”, for the first time.

In pure material design, the previous research has indicated that lots of optimization factors such as used algorithm and parameters have influence on the optimal solution. In other words, there are multiple local minima for the topological design of materials for extreme properties. Therefore, the purpose of this study is to attempt different or more concise algorithms to find much wider possible solutions to material design. As for the design of material microstructures for macro-structural performance, the previous studies test algorithms on 2D porous or composite materials only, it should be demonstrated for 3D problems to reveal numerical and computational performance of the used algorithm.

The presented paper is an attempt to use the strain energy method and the bi-directional evolutionary structural optimization (BESO) algorithm to tailor material microstructures so as to find the optimal topology with the selected objective functions. The adoption of the strain energy-based approach instead of the homogenization method significantly simplifies the numerical implementation. The BESO approach is well suited to the optimal design of porous materials, and the generated topology structures are described clearly which makes manufacturing easy.

As a result, the presented method shows high stability during the optimization process and requires little iterations for convergence. A number of interesting and valid material microstructures are obtained which verify the effectiveness of the proposed optimization algorithm. The numerical examples adequately consider effects of initial guesses of the representative unit cell (RUC) and of the volume constraints of solid materials on the final design. The presented paper also reveals that the optimized microstructure obtained from pure material design is not the optimal solution any more when considering the specific macro-structural performance. The optimal result depends on various effects such as the initial guess of RUC and the size dimension of the macrostructure itself.

This paper presents a new topology optimization method for the optimal design of 2D and 3D porous materials for extreme elastic properties and macro-structural performance. Unlike previous studies, the presented paper tests the proposed optimization algorithm for not only 2D porous material design but also 3D topology optimization to reveal numerical and computational performance of the used algorithm. In addition, some new and interesting material microstructural topologies have been obtained to provide wider possible solutions to the material design.

In this work, an SFEM is proposed for solving acoustic problems by redistributing the entries in the mass matrix to “tune” the balance between “stiffness” and “mass” of discrete equation systems, aiming to minimize the dispersion error. The paper aims to discuss this issue.

This is done by simply shifting the four integration points’ locations when computing the entries of the mass matrix in the scheme of SFEM, while ensuring the mass conservation. The proposed method is devised for bilinear quadratic elements.

The balance between “stiffness” and “mass” of discrete equation systems is critically important in simulating wave propagation problems such as acoustics. A formula is also derived for possibly the best mass redistribution in terms of minimizing dispersion error reduction. Both theoretical and numerical examples demonstrate that the present method possesses distinct advantages compared with the conventional SFEM using the same quadrilateral mesh.

After introducing the mass-redistribution technique, the magnitude of the leading relative dispersion error (the quadratic term) of MR-SFEM is bounded by (5/8), which is much smaller than that of original SFEM models with traditional mass matrix (13/4) and consistence mass matrix (2). Owing to properly turning the balancing between stiffness and mass, the MR-SFEM achieves higher accuracy and much better natural eigenfrequencies prediction than the original SFEM does.

The optimal material microstructures in pure material design are no longer efficient or optimal when accounting macroscopic structure performance with specific boundary conditions. Therefore, it is important to provide a novel multiscale topology optimization framework to tailor the topology of structure and the material to achieve specific applications. In comparison with porous materials, composites consisting of two or more phase materials are more attractive and advantageous from the perspective of engineering application. This paper aims to provide a novel concurrent topological design of structures and microscopic materials for thermal conductivity involving multi-material topology optimization (material distribution) at the lower scale.

In this work, the effective thermal conductivity properties of microscopic three or more phase materials are obtained via homogenization theory, which serves as a bridge of the macrostructure and the periodic material microstructures. The optimization problem, including the topological design of macrostructures and inverse homogenization of microscopic materials, are solved by bi-directional evolutionary structure optimization method.

As a result, the presented framework shows high stability during the optimization process and requires little iterations for convergence. A number of interesting and valid macrostructures and material microstructures are obtained in terms of optimal thermal conductive path, which verify the effectiveness of the proposed mutliscale topology optimization method. Numerical examples adequately consider effects of initial guesses of the representative unit cell and of the volume constraints of adopted base materials at the microscopic scale on the final design. The resultant structures at both the scales with clear and distinctive boundary between different phases, making the manufacturing straightforward.

This paper presents a novel multiscale concurrent topology optimization method for structures and the underlying multi-phase materials for thermal conductivity. The authors have carried out the concurrent multi-phase topology optimization for both 2D and 3D cases, which makes this work distinguished from existing references. In addition, some interesting and efficient multi-phase material microstructures and macrostructures have been obtained in terms of optimal thermal conductive path.

To treat water pollution, especially the contamination resulted from organic dyes has aroused significant attention around the world, this study aims to prepare the metal organic framework (MOF) materials hybridizing with poly(p-phenylene terephthalamide) (PPTA) by means of a facile refluxing method and to systematically investigate adsorption performance for anionic dye Congo red as target molecule from aqueous solution.

The MOF materials hybridized by PPTA were fabricated by virtue of a facile refluxing method, characterized by thermogravimetric analysis, X-ray powder diffraction, Fourier transform infrared and pore structure.

The results showed that pseudo-second-order kinetic model could better describe the adsorption process for all the four materials, whereas Elovich model also fitted the process for the hybrid materials with PPTA. Adsorption isotherm analyses indicated that Langmuir isotherm could be used to describe the adsorption process. Introduction of appropriate amount of PPTA could enhance the adsorption affinity of the MOF materials for Congo red, and the maximum adsorption capacity could reach as high as 1,053.41 mg/g while that of the MOF material without PPTA was 666.67 mg/g, indicating introduction of PPTA could change the microenvironment of the MOF materials and increase the adsorption sites, leading to high adsorption efficiency.

The microstructure of MOF hybridized materials in detail is the further and future investigation.

This study will provide a method to prepare MOF materials with high efficiency to treat anionic dyes like Congo red from aqueous solution.

Owing to the special characteristics of PPTA and similar to carbon tube, PPTA was introduced into MOF material to increased corresponding water stability. Because of aromatic ring and amide group on the surface of PPTA, the adsorption efficiency of the hybridized MOF material with appropriate amount of PPTA was greatly enhanced.

Traditional adaptive analysis based on a coarse mesh, using finite element method (FEM) analysis, produces the original solution. Then post-processing the result and figuring out the regions should be refined and these regions refined once. Finally, this new mesh is used to get the solution of first refinement. After several iterations of above procedures, we can achieve the last result that is closer to the true solution, which takes time, making adaptive scheme inpractical to engineering application. The paper aims to discuss these issues.

This paper based on FEM proposes a multi-level refinement strategy with a refinement strategy and an indicator. The proposed indicator uses value of the maximum difference of strain energy density among the elements that associated with one node, and divides all nodes into several categories based on the value. A multi-level refinement strategy is proposed according to which category the node belongs to refine different elements to different times rather than whether refine or not.

Multi-level refinement strategy takes full use of the numerical calculation, resulting in the whole adaptive analysis that only need to iterate twice while other schemes must iterate more times. Using much less times of numerical calculation and approaches, more accurate solution, making adaptive analysis more practical to engineering.

Multi-level refinement strategy takes full use of the numerical calculation, resulting in the whole adaptive analysis only need iterate twice while other schemes must iterate more times. using much less times of numerical calculation and approaches more accurate solution, making adaptive analysis more practical to engineering.

This study aims to explore the relationship among five types of power (expert, referent, legitimate, reward and coercive power), two dimensions of cooperative behavior (specific investments and communication) and three types of alliance performance (alliance stability, income increase and cost decrease) in contract farming. By investigating the dyadic perspectives of companies and contract farmers, the authors examine how power use influences cooperative behavior, which further enhances alliance performance.

The authors construct a theoretical model grounded on resource dependence theory (RDT). Data from 202 companies and 462 farmers in China are used to test the proposed hypotheses using structural equation modeling.

The authors' results show that the five types of power play different roles in cooperative behavior. On the one hand, farmers' expert, reward and coercive power enhance the company's specific investments; farmers' expert power enhances the company's communication but farmers' coercive power harms the company's communication. Also the company's specific investments enhance communication that is positively related to alliance ability, income increase and cost decrease. On the other hand, the company's expert, referent and legitimate power enhance farmers' communication, while the company's coercive power harms farmers' communication; the company's reward and coercive power enhance farmers' specific investments. Moreover, farmers' communication is positively related to alliance ability, income increase and cost decrease, but farmers' specific investments do not significantly influence such.

This study contributes to the literature on contract farming supply chain management by examining the relationships among power use, cooperative behavior and alliance performance from the dyadic perspective of companies and farmers. These findings have practical implications for agricultural companies and farmers promoting cooperative behavior and alliance performance through appropriate power use in contract farming supply chains.

For moderate pressure and high pressure gear pumps, the temperature failure problem of bearings is now of considerable concern because of their heavy loads. However, the compact structure and the efficiency consideration make it extremely difficult to improve the bearing cooling. A self-circulating oil bearing system is developed for gear pumps with self-lubricating bearings to solve this problem. The oil is aspirated in from the low pressure chamber of the gear pump and discharged to the same chamber by using the pressure difference in the journal bearing, thus achieving the self-circulation.

An experiment test rig has been built for the feasibility study. The oil flow rate under different speeds has been recorded. Furthermore, the temperatures of the bearings with or without the oil circulation have been compared. Additionally, the oil flow in the test rig has been simulated using computational fluid dynamics codes.

The experimental and numerical results agree well. The experimental results indicate that the oil flow rate increases approximately linearly with the speed and the bearing temperature can be lowered successfully. The calculation results indicate that the bearing load capacity is nearly the same. Both the experimental and numerical studies establish that the self-circulating oil bearing system works successfully.

As far as the authors know, it is the first time to find that the self-circulation can be built using the pressure difference in the bearing oil film, and this principle can be applied in the cooling and lubrication of the gear pumps to solve the temperature failure problem.

This paper aims to propose a gradient-based shape optimization framework in which traditional time-consuming conversions between computer-aided design and computer-aided engineering and the mesh update procedure are avoided/eliminated. The scheme is general so that it can be used in all cases as a black box, no matter what the objective and/or design variables are, whilst the efficiency and accuracy are guaranteed.

The authors integrated CAD and CAE by using isogeometric analysis (IGA), enabling the present methodology to be robust and accurate. To overcome the difficulty in evaluating the sensitivities of objective and/or constraint functions by analytic method in some cases, the authors adopt the finite difference method to calculate these sensitivities, thereby providing a universal approach. Moreover, to further eliminate the inefficiency caused by the finite difference method, the authors advance the exact reanalysis method, the indirect factorization updating (IFU), to exactly and efficiently calculate functions and their sensitivities, which guarantees its generality and efficiency at the same time.

The proposed isogeometric gradient-based shape optimization using our IFU approach is reliable and accurate, as well as general and efficient.

The authors proposed a gradient-based shape optimization framework in which they first integrate IGA and the proposed exact reanalysis method for applicability to structural response and sensitivity analysis.

The purpose of this paper is to enhance the feasibility of the edge-based smoothed triangular (EST) element, some modifications are made in this study.

First, an efficient strategy based on graph theory is proposed to construct the edge system. Second, the stress is smoothed in global coordinate system based on edge instead of strain, which makes the theory of EST more rigorous and can be easily extended to the situation of multi elements sharing the same edge. Third, the singular degree of freedoms (DOFs) of the nodes linked by edges are restrained in edge local coordinate system, which makes the global stiffness matrix non-singular and can be decomposed successfully.

First, an efficient edge constructing strategy can make EST element more standout. Second, some modifications should be made to EST element to extend it to the situation with multi elements sharing the same edge, so that EST element can deal with the geometrical models with this kind of features. Third, the way to restrain the singular DOFs of EST element must be different from normal isoparametric triangle element, because the stiffness matrix of the smoothing domain is not computed in local coordinate system.

The modified EST element performs stably in engineering analysis including large scale problems and the situation with multi elements sharing the same edge, and the efficiency of edge system constructing is no longer the bottleneck.