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The relations between China and Singapore were once exampled as good bilateral relations in the region: stable and promising. Albeit gradually increasing competition, bilateral economic cooperation remains to be a stabilizer. However, the ambitious Belt and Road Initiative (BRI) and even more complicated Sino-US relations add up more uncertainties to bilateral relations. This paper aims to examine the fragility of bilateral relations against the overall backgrounds of the dynamic regional balance of power while analyzing the economic cooperation as the stabilizer and reviewing political mutual trust between China and Singapore.

This paper will apply historical and documentary review and qualitative analysis.

Led by its pragmatic foreign policy, Singapore hedges against China, even it seeks to deeply engaging China in all dimensions of bilateral ties, including economic, cultural and political. The grand strategy of the BRI signals the era of “keeping low profile”, leaving us far away. It will inevitably change the regional landscape geo-strategically. The USA clearly defines China as a strategic competitor, which represent Sino-US relations will not go back to the past. The traditional counterbalance strategy applied by Singapore works more difficultly when China intends to be stronger politically in the region. Economically and politically, there are no reasons for Singapore not to show positive support for the BRI. However, the BRI essentially provides a warning message that Singapore should explore a more practical and realistic strategy for not being constrained by China's geo-economic strategy. Singapore's picking side and its increasing military budget, China's assertiveness and the changing Sino-US relations imply the looming fragilities to bilateral relations.

The relations between China and Singapore were once exampled as good bilateral relations in the region: stable and promising. However, China and Singapore relations also ran into bumps from time to time over the years. We usually believe it is because of the peculiarity of Singapore's China policy. However, we should not neglect the dynamic regional balance of power and the changing Sino-US relations after the BRI was proposed. To fill this research gap, this paper will review the factors of stabilizers and the factors that bring fragility to bilateral relations between China and Singapore. The paper also argues that it is time for Beijing to make reflections on whether Beijing proposed BRI too early and whether Beijing over addressed on the magnificence and ambitions of the BRI.

This paper aims to analyze the dominant stray parameters of the DC bus bar and focus on weakening the influence of the stray parameters instead of reducing the value of the stray parameters in DC bus bar while switching. By finding the mechanisms to reduce the effects of stray parameters on switching transient, the simple and straightforward optimization methods could be given for the engineering designer.

The investigations are focused on the equivalent circuit by segmented impedance evaluation in the low-frequency band and the energy propagation by wave impedance evaluation in the high frequency band. This paper proposes an equivalent impedance calculation model to locate the dominant stray parameters in the DC bus bar and takes the energy propagation characteristics using wave impedance into consideration, which can simplify the optimization design of DC bus bar.

According to the equivalent circuit and electromagnetic field analysis, this paper proves the existence of the dominant stray parameters in DC bus bar that is widely used on high-power converters and certifies that not all the stray parameters in different areas of DC bus bar have the same effects on switching process, which can give a good guidance for the optimization design of DC bus bar.

The positions of DC-link capacitors, resulting in only part of stray parameters in DC bus bar has more impact during switching, are significant to the DC bus bar optimization design. These stray parameters named dominant stray parameters in this paper play a leading role in the switching transient process. The area of DC bus bar, which is close to IGBTs and far from DC-link capacitors, contains the dominant stray parameters in the switching transient process. Therefore, the distance between DC-link capacitors and IGBTs should be shortened as much as possible. Based on the results, the efficiency for the DC bus bar optimization design could be improved by weakening the influence of the stray parameters, such as reducing the dominant stray parameters only. Therefore, it can save the cost and time of DC bus bar optimization design.

This work aims to develop a new kind of semicrystalline polymer filament and optimize its printing parameters in the fused deposition modeling process. The purpose of this work also includes producing FDM parts with good ductility.

A new kind of semicrystalline filaments composed of long-chain polyamide (PA)1012 was prepared by controlling screw speed and pulling speed carefully. The optimal printing parameters for PA1012 filaments were explored through investigating dimensional accuracy and bonding strength of FDM parts. Furthermore, the mechanical properties of PA1012 specimens were also evaluated by varying nozzle temperatures and raster angles.

It is found that PA1012 filaments can accommodate for FDM process under suitable printing parameters. The print quality and mechanical properties of FDM parts highly depend on nozzle temperature and bed temperature. Even though higher temperatures facilitate stronger interlayer bonding, FDM parts with excellent tensile strength were obtained at a moderate nozzle temperature. Moreover, a bed temperature well above the glass transition temperature of PA1012 can eliminate shrinkage and distortion of FDM parts. As expected, FDM parts prepared with PA1012 filaments exhibit good ductility.

Results in this work demonstrate that the PA1012 filament allows the production of FDM parts with desired mechanical performance. This indicates the potential for overcoming the dependence on amorphous thermoplastics as a feedstock in the FDM technique. This work also provides insight into the effect of materials properties on the mechanical performance of FDM-printed parts.