Wave Mode Control of Cantilever Slab Structure of T-Beam Bridge with Large Aspect Ratio

The cantilever plate structure in a T-beam bridge with a large aspect ratio will cause vibration under the influence of environmental disturbance and self-stress, resulting in fatigue damage of the plate structure. Wave control based on elastic wave theory is an effective method to suppress the vibration of the cantilever plate structure in a beam bridge. Based on the classical thin plate theory and the wave control method, the active vibration control of the T-shaped cantilever plate with a large aspect ratio in the beam bridge is studied in this paper. The wave mode control strategy of structural vibration is analyzed and studied, the controller is designed, the vibration mode function of the cantilever plate is established, and the control force/sensor feedback wave control is implemented for the structure. The dynamic response of the cantilever plate before and after applying wave control force is analyzed through numerical examples. The results show that the response of the structure is intense before control, but after wave control, the structure increases damping, absorbs the energy carried by the elastic wave in the structure, weakens the sharp response, and changes the natural frequency of the structure to a certain extent.

BSA-Coated Gold Nanorods for NIR-II Photothermal Therapy

The second near infrared window is considered to be the optimal optical window for medical imaging and therapy as its capability of deep tissue penetration. The preparation of the gold nanorods with long wavelength absorption and low cytotoxicity is still a challenge. A series gold nanorods with large aspect ratio have been synthesized. Strong plasma absorption in the second near infrared window from 1000 to 1300 nm could be observed. The biocompatibility of the synthesized gold nanorods is dramatically improved via coating by bovine serum albumin (BSA), while the optical properties of which remains. The breast cancer tumor-bearing mouse could be well treated by the prepared gold nanorods with the NIR-II light intensity as low as 0.75 W/cm2. In summary, these results demonstrate the feasibility of using low illumination dose to treat tumor in the NIR-II region via the large aspect ratio gould nanoparticles.

Analysis and Test of Conductive Shaft of Large Horizontal NC ECM Machine Tool

In order to solve the problems of serious heating and easy ablation of conductive shaft in electrochemical machining of special-shaped deep hole with large aspect ratio, the two schemes of single side copper bar and symmetrical copper bar of conductive shaft were studied by ANSYS software. And the conductive shaft scheme based on symmetrical copper bar scheme was determined. The thermoelectric coupling model of the conductive shaft was established to analyze the distribution law of temperature field and thermal deformation of conductive shaft under different working conditions. Through the machining test of special-shaped inner spiral deep hole parts with large aspect ratio, the results show that under the conditions of working current of 15 000 A, feed rate of 5 mm/min and continuous machining for 14 hours, the forming accuracy of the workpiece is ±0.15 mm and the surface roughness is better than Ra0.8 µm. The performance of the conductive shaft is stable and meets the actual processing requirements. The heat dissipation performance of the conductive shaft can be optimized by providing air flow on the upper surface and side at the same time.

Turbulent Flow Around Rectangular Cylinders with Different Streamwise Aspect Ratios

Turbulent flows around a square cylinder and a rectangular cylinder with a streamwise aspect ratio of 5 in a uniform flow were investigated using time-resolved particle image velocimetry. The Reynolds number based on the cylinder height and oncoming flow velocity was 16200. Similarities and differences in the flow dynamics over the cylinders and in the near wake region were examined in terms of the mean flow, Reynolds stresses and triple velocity correlations. The budget of turbulent kinetic energy as well as temporal and spectral analyses were also performed. The results show that the primary, secondary and wake vortexes are smaller for the square cylinder compared to the large aspect ratio cylinder. There are regions of elevated Reynolds stresses and triple velocity correlations along the mean separating streamlines, and the magnitudes of these statistics are an order of magnitude higher over the square cylinder compared to the large aspect ratio cylinder. The topology of the triple velocity correlations shows low-speed ejection and high-speed sweep events, respectively, transporting instantaneous Reynolds normal stresses away from the mean separating streamline into the free-stream and toward the cylinder surface, regardless of aspect ratio. Near the leading and trailing edges of both cylinders, regions of negative turbulence production are observed and the dominant components contributing to this occurrence are discussed. Temporal autocorrelation coefficients of the streamwise and vertical velocity fluctuations show a periodic trend, with a periodicity that is directly linked to the Kármán shedding frequency and its second harmonic.

Polymerization Shrinkage of Short Fiber Reinforced Dental Composite Using a Confocal Laser Analysis

The purpose of this study was to investigate the polymerization shrinkage of short fiber reinforced composite (SFRC) using a multicolor confocal displacement laser that can measure the polymerization shrinkage with high accuracy. The three types of SFRCs used in this study were XD (Ever X Flow Dentin), XB (Ever X Flow Bulk), and XP (EverX Posterior). In addition, CF (Clearfil majesty ES Flow) with hybrid type filler was used as a control. The measured values of the final polymerization shrinkage rate and amount of polymerization shrinkage rate when the polymerization shrinkage rate became constant (less than 0.1 µm/s) were approximated for all SFRCs. XP had a large aspect ratio of glass fiber filler and showed a significant difference from XD with a small aspect ratio (p < 0.05). There was no significant difference in the measured value of time when the polymerization contraction reached a constant speed (0.1 µm/s or less) for all SFRCs (p > 0.05). There was no significant difference in the measured values of polymerization shrinkage rate after the polymerization shrinkage reached a constant rate for all SFRCs (p > 0.05). These results show that glass fiber with large aspect ratio can alleviate polymerization shrinkage stress. The polymerization behavior of SFRC was found to be dependent on the amount of glass fiber filler, aspect ratio, and orientation.