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The symmetry error generated in the machining process of herringbone gears will destroy the stability of the transmission system. The purpose of this paper is to establish a symmetry error measurement model of herringbone gear based on spiral measurement method, and to evaluate the transmission accuracy of herringbone gear based on the measured symmetry error.

A symmetry error measurement model of herringbone gear based on spiral measurement method is proposed. The measurement method is verified by three coordinate measuring instrument. The transmission error analysis model of herringbone gear is established. The influence of speed and load on it is analyzed.

At the same speed, when the load increases from 100 N·m to 500 N·m, the transmission error increases and the transmission accuracy of the system decreases. Under the same load, the speed is increased from 100 rpm to 500 rpm, which has little effect on the transmission error.

The measurement method and analysis model used in this paper provide reference value and significance for the measurement and analysis of symmetry error.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2024-0350/

Adopting the context, input, process and product (CIPP) evaluation assessment model, this study aims to achieve three objectives: (1) to identify the characteristics of educational activities conducted by the International Table Tennis Federation (ITTF) museum; (2) to explore the key factors that promote and optimize the educational objectives of the ITTF museum and (3) to develop a framework that attempts to unpack the complex and dynamic processes of activities conducted by the ITTF museum.

A qualitative research using in-depth interviews was conducted to explore the functions and activities of the ITTF museum.

The path of educational activities carried out is expressed in four aspects: (1) educational background including philosophy and purpose, advantages possessed and the learning needs and readiness of the audience; (2) the resource input includes resource allocation, venue structure, funding channels and the basis of activity program design; (3) the educational activity process includes external cooperation and exchange, the specific content of the activity programs, the teaching strategies and methods during the activities and the response to the challenges of the epidemic and (4) the results of the activities include the number of audience and population distribution, evaluation and feedback of the activities, ways and means of promoting the activities and difficulties and challenges faced.

In the follow-up studies, quantitative research can be conducted by developing a questionnaire based on the current study’s findings. Evaluation scales can be set to continue to enrich and improve the uncovered research content, which is conducive to promoting the objectives of the ITTF museum and giving full play to the educational function, thus enriching the research of sports museums.

The contributions of this study are as follows. First, it enriches the application of the CIPP assessment model in the context of sports museums. It helps the ITTP museum better perform its educational function and provides a reference for future activities of sports museums.

This study aims to optimize the preparation conditions and modify the nanofiltration (NF) membranes to prepare high-performance polysulfone/sulfonated polysulfone composite nanofiltration (PSF/SPSF-NF) membranes through interfacial polymerization.

Investigating the impacts of anhydrous piperazine (PIP) concentration, trimesoyl chloride (TMC) concentration and basement membrane type on NF membrane performance, the optimal membrane was prepared. In addition, nano-SiO₂ was added to the active separation layer to modify the NF membranes.

The comprehensive performance of PSF/SPSF-NF membranes was optimized when the concentration of PIP was 0.75 Wt.% and the concentration of TMC was 0.15 Wt.%, at which time the water flux was 66.1 L·m⁻²·h⁻¹ and the retention rate of Na₂SO₄ was 98.1%. The comprehensive performance of polysulfone/sulfonated polysulfone-SiO₂ nanofiltration (PSF/SPSF-SiO₂-NF) membranes was optimized when the blending ratio of nano-SiO₂ to PIP was 2:3, with a pure water flux of 81.9 L·m⁻²·h⁻¹ and a Na₂SO₄ retention rate of 95.9%. Compared to polysulfone nanofiltration (PSF-NF) membranes and PSF/SPSF-NF membranes, NF membranes with nano-SiO₂ increased the flux recovery rate by 22.9% and 8.7%.

PSF/SPSF-SiO2-NF membrane exhibits excellent antifouling properties.

There is currently no literature available on the preparation of NF membranes using polysulfone/sulfonated polysulfone (PSF/SPFS) as a substrate. This provides a method for modifying NF membranes, starting with the modification of the basement membrane and then modifying the active separation layer.