ABSTRACT
Steel cables used to raise sluices require a layer of corrosion-resistant grease, which must be periodically replaced. It is time-consuming and laborious, and conventional manual cleaning, mechanical cleaning, and chemical cleaning methods have many drawbacks. In this paper, a nanosecond pulsed fiber laser is used to clean hardened surface grease from such cables. An experimental system was designed to study the effects of parameters such as the laser power, scanning speed, cleaning frequency, and defocusing amount. Macroscopic and microstructural observations were conducted on the surfaces of steel cables before and after cleaning using cameras, optical microscopy, scanning electron microscopy, and energy dispersive spectrometry. With the optimal parameters, laser cleaning can effectively remove hardened grease from steel cable surfaces without damaging the galvanized layer and the steel wire matrix. Ablation, gasification, and evaporation are the main mechanisms by which grease and dirt are removed. This study lays a foundation for optimizing the laser cleaning of steel sluice cables at work sites.
ABSTRACT
Polycarboxylate superplasticizers (PCEs) are indispensable functional ingredients in modern construction, and their usage is extensive. Herein, a polyether macromonomer (VPEG) with high reactivity was used to prepare VAPCEs with different interfacial adsorption properties (acid-ether ratio) at low temperatures and reacted in 30 min. The effects of various VAPCEs on the fluidity, rheology, and strength of cement were investigated with a w/c (water/cement) ratio of 0.35. Results showed that VAPCE-3 (acid-ether ratio is 3) exhibited the best dispersion, and the fluidity of cement slurry with VAPCE-3 (280 mm) is 278.38% higher than that of the control sample (74 mm). The reason is summarized as VAPCE-3 having good adsorption performance on the surface of cement particles and having a large steric hindrance between particles. The compressive strength of cement with VAPCE-3 was enhanced by 8.29% compared with pure cement in 3 days of curing age due to its densification on microstructure and lowest R orientation index of calcium hydroxide. With the amount of acrylic acid in VAPCE increasing, the flexural strength enhanced because a more cross-linking network was formed with Ca2+ in cement with the increase of COO- content in VAPCEs.
ABSTRACT
To understand potential users' behavioral intention (BI) to adopt new energy vehicles (NEVs), a media-based perceptions and adoption model (MPAM) of NEVs geared toward potential NEV consumers was constructed based on social cognition theory, the technology acceptance model, the value acceptance model, perceived risk theory, and the MPAM of autonomous vehicles (AVs). A sample survey including 309 NEV potential users was conducted and the results were analyzed through SPSS 24.0 and SmartPLS 3.0 to test the model and verify the research hypotheses. The results show that mass media (MM) has a direct influence on users' social norms (SNs) and part of product perceptions, and an indirect influence on their BI to adopt NEVs; SNs have a direct influence on product perception, and also indirectly affect BI toward NEVs. Product perception directly and significantly affects BI; perceived usefulness (PU), perceived ease of use (PEOU), and perceived enjoyment (PE) have a positive and significant influence on BI, while both perceived cost (PC) and perceived risk (PR) have a negative and significant impact. This study is a theoretical extension of the technology acceptance model (TAM) to green product adoption scenarios, such as NEVs, in the face of the external stimuli from MM information; it proposes product perception variables and media information effects that are different from the MPAM of AVs. The results are expected to greatly promote NEV design and marketing.
