No abstract

No abstract

Calibration of inertial measurement units (IMU) is carried out to estimate the coefficients which transform the raw outputs of inertial sensors to meaningful quantities of interest. Based on the fact that the norms of the measured outputs of the accelerometer and gyroscope cluster are equal to the magnitudes of specific force and rotational velocity inputs, respectively, an improved multi-position calibration approach is proposed. Specifically, two open but important issues are addressed for the multi-position calibration: (1) calibration of inter-triad misalignment between the gyroscope and accelerometer triads and (2) the optimal calibration scheme design. A new approach to calibrate the inter-triad misalignment is devised using the rotational axis direction measurements separately derived from the gyroscope and accelerometer triads. By maximizing the sensitivity of the norm of the IMU measurement with respect to the calibration parameters, we propose an approximately optimal calibration scheme. Simulations and real tests show that the improved multi-position approach outperforms the traditional laboratory calibration method, meanwhile relaxing the requirement of precise orientation control.

Summary: A new charring agent (CA), a derivative of triazines, was synthesized. The flame retardancy and thermal behavior of a new intumescent flame‐retardant (IFR) system for PE (PE‐IFR) were investigated by limited oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA), and FTIR spectroscopy. The TG curves shows that the amount of residue of IFR‐PE system are largely increased compared to those of PE at temperatures ranging from 350 to 700 °C. The new PE‐IFR system can apparently reduce the amount of decomposing products at higher temperatures and promotes the formation of carbonaceous charred layers. It showed a distinct synergistic flame retardant effect (SE) between nitrogen and phosphorus. The flame retardant PE composition was optimized to achieve a LOI value of 31.2 and UL‐94 V‐0 performance with the synthesized charring agent, ammonium polyphosphate (APP).TG curves of PE, APP, CA, and different PE/CA/APP systems.magnified imageTG curves of PE, APP, CA, and different PE/CA/APP systems.

ABSTRACT:The lowering of ignitability and flammability of polyethylene (PE) and the production of fire-retarding materials has become an urgent problem because of the demand of fire safety. In our article, a new charring agent (CA), a derivative of triazines, was synthesized by charging 2-amino-4,6-dichloro-s-triazines and diethylenetriamine into a reactor to conduct the solution polycondensation reaction, and the synthetic conditions of monomer and CA, such as temperature, time, etc., were investigated. Both the monomer and the resulting polymer were characterized by mass spectrum (MS), Fourier transform infrared (FTIR) spectroscopy, 1 H-NMR, and elemental analysis. The intrinsic viscosities and flame-retardancy property of CA were also studied. It was found that the incorporation of ammonium polyphosphate (APP) and CA into low-density polyethylene (LDPE) has a distinct effect on thermal and flame-retardancy behavior.