Geometric transmission error model analysis of high precision F2C-T drive
According to the structure of the newly high precision F2C-T pin-cycloid transmission, influence factors on the transmission error were analyzed, and the error synthesis model of the various driving factors and parts were established. Taking the F2C-T455 model as an example, the theory of transmission error were analyzed, comparing contribution rate by driving factors of each part, the main influence factors of transmission error of the system were obtained.
Numerical estimation of dynamic transmission error of gear by using quasi-flexible-body modeling method
When the power transmission systems are designed or improved, an understanding of gear dynamics is essential and very important. Gear systems are not easy to investigate because gear noise has to be carefully controlled. As a result, when designing and developing gear transmission systems, it is very important to grasp the noise and reduce it. Also, it is necessary to make a clear distinction between rattle noises and whine noises. The rattle noise occurs by mainly hitting the tooth, and whine noise occurs by mainly rubbing the tooth in meshing. Therefore, the whine noise is relatively related to high frequency characteristics. Our aim was to find a good way to evaluate whine noise with a numerical approach. When the gear dynamics are investigated to evaluate the whine noise, the dynamic transmission error (DTE) can be utilized. But, it is very difficult to obtain the DTE results by means of not only experimental ways but also numerical calculations. Although multi-body dynamics software has not been able to calculate the DTE practically yet, there is a possibility that the software can get the DTE results. Therefore, we propose a numerical modeling method to obtain the DTE results by using multi-body dynamics software (RecurDyn). To reduce the calculation time and represent flexibility, a rotational joint and force element with the bending stiffness are applied between gear teeth and trunk. Also the numerical results have been compared with the experimental data. The results show a good agreement with the experimental results.
Recent progress in engineering near-infrared persistent luminescence nanoprobes for time-resolved biosensing/bioimaging
Persistent luminescence nanoprobes (PLNPs) can remain luminescent after ceasing excitation. Due to the ultra-long decay time of persistent luminescence (PersL), autofluorescence interference can be efficiently eliminated by collecting PersL signal after autofluorescence decays completely, thus the imaging contrast and sensing sensitivity can be significantly improved. Since near-infrared (NIR) light shows reduced scattering and absorption coefficient in penetrating biological organs or tissues, near-infrared persistent luminescence nanoprobes (NIR PLNPs) possess deep tissue penetration and offer a bright prospect in the areas of in vivo biosensing/bioimaging. In this review, we firstly summarize the design of different types of NIR PLNPs for biosensing/bioimaging, such as transition metal ions-doped NIR PLNPs, lanthanide ions-doped NIR PLNPs, organic molecules-based NIR PLNPs, and semiconducting polymer self-assembled NIR PLNPs. Notably, organic molecules-based NIR PLNPs and semiconductor self-assembled NIR PLNPs, for the first time, were introduced to the review of PLNPs. Secondly, the effects of different types of charge carriers on NIR PersL and luminescence decay of NIR PLNPs are significantly emphasized so as to build up an in-depth understanding of their luminescence mechanism. It includes the regulation of valence band and conduction band of different host materials, alteration of defect types, depth and concentration changes caused by ion doping, effective radiation transitions and energy transfer generated by different luminescence centers. Given the design and potential of NIR PLNPs as long-lived luminescent materials, the current challenges and future perspective in this rapidly growing field are also discussed.