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This paper aims to study frictional characteristics of thin-walled tubes in the liquid impact forming (LIF) process.

LIF experiments under various impacting velocities were performed on SUS304 stainless steel tubes with various guiding lengths on a custom-designed measurement system to investigate the effects of impacting velocity and guiding length on the coefficient of friction (COF) in the guiding zone.

The results indicate that the COF changes dynamically in the guiding zone and decreases with the deformation process. The reduction range of the COF is wider in LIF than in both the conventional and pulsating hydroforming (THF), which may be contributed to the impacting velocities in a short time. Moreover, the COF decreases faster in the first half of the LIF process than in the second half. Under different impacting velocities and guiding lengths, the decreasing rate of the COF in the first half is more sensitive and obvious than that in the second half.

A method for determining the COF in the guiding zone in LIF is proposed and the frictional characteristics in LIF are studied. Comparing the COF of tubes in conventional THF, pulsating THF and the LIF process is valuable for improving and predicting the tubular formability in various hydraulic environments for industrial production.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2019-0269

This paper aims to examine whether labour unions influence labour conflicts and this mechanism is different in China compared with other countries.

This paper uses the data from the China Employer–Employee Survey that interviewed 1,208 firms and 10,087 workers in 2016 as the measurement of variables, and it uses Logit regression model to do the empirical research.

Unions cannot significantly influence labour conflicts. More active unions and unions whose leaders are appointed by the firms’ management are associated with a higher incidence of labour conflicts.

This paper finds a new mechanism that explains the relationship between unions and labour conflicts. The existing literature states that unions may increase labour conflicts via “monopoly power” and may also mitigate labour conflicts via “voice mechanisms”. This paper’s findings show that the positive correlation between unions and labour conflicts may be explained by the lack of “voice mechanism” rather than “monopoly power”. The findings imply that labour unions should represent the interest of workers to mitigate the increasing labour conflicts.

The process of hydroforming is defined as the formation of parts into the internal mold design using internal pressure. This process can extensively reduce parts and secondary operations, and adoption to the loading path is one of its most essential points. The purpose of this paper is to address these issues.

A dynamic loading path was taken into account in the current study, and a drop hammer was employed for this purpose, decreasing the time and requiring less number of systems.

One of the main observations of this research is that selecting side punches with a smaller central hole radius is proportional to the kinetic energy and the amount of fluid. Moreover, it can be effective in achieving the optimal loading path.

In addition to experiments for numerical analyses, the finite element simulation model was provided via Abaqus software in which the Eulerian–Lagrangian coupling method was utilized for evaluating the tube forming process through repeating the fluid flow formation because of the effect. Moreover, the genetic programming model was efficient for determining the most suitable input parameters regarding prediction for the minimum thickness which examined the efficiency of the process and presented a mathematical relationship.

The purpose of this paper is to examine the changes in B‐share discounts across 76 Chinese stocks around an important regulatory event to understand the importance of political risk in pricing stocks in emerging markets.

On February 19, 2001, the Chinese Securities Regulatory Commission announced that Chinese residents would be allowed to own B‐share classes of stocks traded on both the Shanghai and Shenzhen stock markets. These share classes were previously restricted to foreign investors while domestic residents were only permitted to hold A‐share classes of stock and were typically priced at a significant discount. This regulatory change triggered a dramatic decline of prevailing B‐share discounts from 80 percent down to 40 percent.

The paper finds that the largest declines in the B‐share discounts around this regulatory event are concentrated in the firms with low government ownership stakes and are unrelated to the firms' risks, relative supplies of shares outstanding and liquidity attributes.

This surprising finding challenges the current wisdom about what influences the B‐share discount and particularly the role of political risk in explaining the discount puzzle.

The paper offers an alternative interpretation for the B‐share discount puzzle. The findings have important implications for China's future financial liberalization policies.