Dynamic Response of a Casting Crane Rigid-Flexible Coupling System to High Temperature

To determine the influence of temperature on the mechanical properties of crane metal structures, three Q355 alloy steel samples were processed and their elastic moduli were tested at different temperatures using a metal tension test bed. The constitutive equation for the elastic modulus of Q355 alloy steel at different temperatures was predicted using test data and a neural network algorithm. Based on crane structural characteristics and the principle of system dynamics, a coupling vibration model was established that included the crane flexible girder, cabin, trolley, crane, and temperature. System motion equations were established according to the Lagrange equation, and the approximate solution of nonlinear system vibration was solved by the direct integration method (the Newmark method). The dynamic characteristics of the main beam and cabin were analyzed at different temperatures, as well as safety during service. The results show that, with increasing temperature, the maximum midspan displacement of the main beam increases gradually, by 14.3%, 21.4%, and 57.1% at temperatures of 300°C, 400°C, and 600°C, respectively. The cabin vibration displacement increases with temperature, by up to 32.5% at 600°C, but the influence of temperature on cabin vibration acceleration is not obvious. It was concluded that the influence of temperature on the dynamic characteristics of the main beam must be considered during the design stage of cranes. The proposed model and analysis method provide a theoretical basis for the design of casting cranes according to temperature

Phase-type Fresnel zone plate with multi-wavelength imaging embedded in fluoroaluminate glass fabricated via ultraviolet femtosecond laser lithography

Herein, we report a novel optical glass material, fluoroaluminate (AlF3) glass, with excellent optical transmittance from ultraviolet to infrared wavelength ranges, which provides more options for application in optical devices. Based on its performance, the phase-type Fresnel zone plate (FZP) by ultraviolet femtosecond (fs) laser-inscribed lithography is achieved, which induces the refractive index change by fs-laser tailoring. The realization of ultraviolet fs-laser fabrication inside glass can benefit from the excellent optical performance of the AlF3 glass. Compared with traditional surface-etching micro-optical elements, the phase-type FZP based on AlF3 glass exhibits a clear and well-defined geometry and presents perfect environmental suitability without surface roughness problems. Additionally, optical focusing and multi-wavelength imaging can be easily obtained. Phase-type FZP embedded in AlF3 glass has great potential applications in the imaging and focusing in glass-integrated photonics, especially for the ultraviolet wavelength range.Published versio

A Flexible Multifunctional PAN Piezoelectric Fiber with Hydrophobicity, Energy Storage, and Fluorescence

Lightweight, flexible, and hydrophobic multifunctional piezoelectric sensors have increasingly important research value in contemporary society. They can generate electrical signals under the action of pressure and can be applied in various complex scenarios. In this study, we prepared a polyacrylonitrile (PAN) composite fiber doped with imidazolium type ionic liquids (ILs) and europium nitrate hexahydrate (Eu (NO3)3·6H2O) by a facile method. The results show that the PAN composite fibers had excellent mechanical properties (the elongation at break was 114% and the elastic modulus was 2.98 MPa), hydrophobic self-cleaning ability (water contact angle reached 127.99°), and can also emit light under UV light irradiation red fluorescence. In addition, thanks to the induction of the piezoelectric phase of PAN by the dual fillers, the composite fibers exhibited efficient energy storage capacity and excellent sensitivity. The energy density of PAN@Eu-6ILs reached a maximum of 44.02 mJ/cm3 and had an energy storage efficiency of 80%. More importantly, under low pressure detection, the sensitivity of the composite fiber was 0.69 kPa−1. The research results show that this PAN composite fiber has the potential to act as wearable piezoelectric devices, energy storage devices, and other electronic devices

Tailoring Polyethylenes by Nickel Complexes Bearing Modified 1‑(2-Benzhydryl­naphthylimino)-2-phenylimino­acenaphthylene Derivatives

A series of 1-(2-benzhydryl­naphthylimino)-2-phenylimino­acenaphthylene derivatives (<b>L1</b>–<b>L5</b>) was synthesized, characterized, and then reacted with (DME)­NiBr₂ to form the corresponding [1-(2-benzhydryl­naphthylimino)-2-phenylimino­acenaphthyl]­nickel bromides (<b>C1</b>–<b>C5</b>). All nickel complexes were fully characterized by their FT-IR spectra and elemental analysis. The molecular structures of the representative complexes <b>C1</b> and <b>C4</b> were also determined by single-crystal X-ray diffraction. On activation with either methylaluminoxane (MAO) or diethylaluminum chloride (Et₂AlCl), all title nickel complexes showed high activities toward ethylene polymerization; the resulting polyethylenes showed molecular weights higher than those obtained by using the nickel analogues bearing (2-benzhydryl­naphthylimino)­pyridines and also had branches lower than those obtained by using other diiminoacenaphthylnickel analogues. Therefore, the modification of ligands could affect the catalytic behavior of their nickel complexes in order to tailor the molecular weights and branches of the resulting polyethylenes

Enhancing the Activity and Thermal Stability of Nickel Complex Precatalysts Using 1‑[2,6-Bis(bis(4-fluorophenyl)methyl)-4-methyl phenylimino]-2-aryliminoacenaphthylene Derivatives

The series of acenaphthylene-1-[2,6-bis­(bis­(4-fluorophenyl)­methyl)-4-methylphenylimino]-2-arylimine derivatives and their dichloronickel complexes were synthesized and fully characterized as well as the single-crystal X-ray diffraction of representative nickel complexes, revealing a distorted tetrahedral geometry. Upon activation with either MAO or Et₂AlCl, all nickel complexes showed high activities in ethylene polymerization; moreover, their catalytic systems showed better thermal stabilities on being manipulated at 80 °C as the industrial operating temperature