A general solution of the spherical thermo-acoustic (TA) radiation from any solid in gas is derived by using a fully thermally-mechanically coupled TA model. Therefore, the characteristics and regularities of spherical TA emission can be studied more completely. It is shown that flat amplitude-frequency response, the most important feature for planar TA emission from technical standpoint, still exists for spherical TA emission, and changes with the radius of a sphere, thickness of TA sample, and the distance from surface. This expression agrees well with experimental and theoretical results of planer TA emission for much larger sphere and lays the foundation to calculate complex TA emission problems

Late-transition-metal (LTM) catalysts are a family of very flexible ethylene polymerization catalysts because their catalytic performance can be easily adjusted by modifying the ligand structure. Their less oxyphilicity character, which may promote the production of copolymers from ethylene and polar comonomers, is another aspect that attracts much attention in both academic and industrial fields. The immobilization of LTM catalysts on spherical supports is a crucial step prior to their use in the industrial processes of gas-phase or slurry polymerizations. This paper reviews recent developments in supported LTM catalysts for olefin polymerization, and summarizes loading methods and mechanisms of the immobilization of LTM catalysts on inorganic, organic, and inorganic-organic materials, and the effects of immobilization on catalytic activity, polymerization mechanism, and polymer morphology. [22,23] are applied to olefin polymerization. The products obtained using such catalysts can be changed from polyethylene (PE) to oligomers by tuning the steric and electronic properties of the ligands [24]. Bulky complexes can produce high-molecular-weight branched PE, without the addition of α-olefin comonomers, in the presence of methylaluminoxane (MAO). Some bulky catalysts with special backbone such as camphyl and acenaphthyl show highly thermal stability and good control ability for olefin polymerization [25]. Late transition-metals are more suitable for the copolymerization of ethylene with commercial polar olefins because of their better tolerance of polar functional groups. Only amorphous polymers can be obtained if the polymerization is catalyzed by homogeneous catalysts, inevitably leading to reactor fouling in industrial units. To meet the requirements of continuous industrial gas-phase or slurry polymerization units, a crucial step for the industrialization of LMT catalysts is the immobilization of such catalysts on spherical supports to obtain morphologically uniform polymer particles. late-transition-metal complexes, diimine, immobilization, olefin polymerization

We propose and demonstrate a fiber optical trap based on the coexistence of LP01 and LP11 modes for the simultaneous trapping of both high refractive index particles and low refractive index particles. Since different mode beams have different propagation constants, they exhibit different focused light fields. We fabricated a tapered fiber probe using thermal fusion to converge the beam, which generates a strong gradient force field near the fiber tip, as well as a dark trap along the axial direction. High refractive index particles are attracted near the fiber tip by a strong gradient force, and low refractive index particles are trapped in the dark cage along the axial direction. The proposed optical trap, which can simultaneously trap particles with different refractive indices, makes it easier to manipulate cells or molecules with different properties and explore multi-molecule interactions, which can facilitate research related to biology and chemistry.

The rapid and accurate detection of partial discharges (PD) ensures the safe operation of the power grid. It is important to improve the reliability of power supply. When a partial discharge (PD) occurs, acoustic wave will be produced. Usually the partial discharge (PD) produces an acoustic wave frequency of about a few kHz in the gas. This article will use the acoustic simulation module in the Comsol Multiphysics software to simulate the propagation of ultrasonic waves inside and outside the switchgear. Since the transmission of ultrasonic waves is affected by many factors, the geometry of the switchgear is the main factor affecting the propagation of ultrasonic waves. Therefore, this paper will simulate the transmission process of ultrasonic waves under different conditions. Exploring the impact of different monitoring locations on monitoring results through simulation. Through the analysis of the simulation results of the ultrasonic propagation process, we got the following conclusions. As the thickness of the switchgear cabinet increases, it only affects the amplitude of the signal. Opening a hole in the cabinet of the switchgear makes it easier to detect ultrasonic signals outside the cabinet. As the number of openings in the cabinet of the switch cabinet increases, the amplitude of the signal monitored outside the cabinet increases. Four monitoring points are placed on the front, back, upper and lower sides of the switchgear cabinet. Through the simulation of the ultrasonic transmission process, it can optimize ultrasonic testing method and provide guidance for the detection method of ultrasonic waves in production activities.

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We propose a microsphere-assisted Fabry–Perot interferometry (MAFPI) for microstructure measurement. We stretch the single-mode fiber and combine it with microspheres of different sizes and refractive indices, which can form super-focused spots with different characteristics, that is, a photonic nanojet phenomenon. As a proof of principle, we performed scanning imaging of optical discs and holographic gratings by MAFPI. The optical disc image obtained by MAFPI is consistent with the result obtained by a scanning electron microscope, and the obtained grating image is consistent with the actual result.

The kinematics model was built based on the principle of ultrasonic deep rolling (UDR) with longitudinal-torsional vibration (LTV), and the trajectory equations of any particles on edge of the roller involved in the process were given; the influences of vibration parameters including phase angle, frequency of LTV, amplitude of longitudinal vibration, amplitude ratio and the rolling process parameters including roller radius, rolling depth, feed rate, the rotation frequency of roller on the trajectory, acoustic system design and processing quality were discussed. The results can provide theoretical basis for the design of acoustic system and optimization of process parameters.

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