DEM PARAMETERS CALIBRATION OF MIXED BIOMASS SAWDUST MODEL WITH MULTI-RESPONSE INDICATORS

Taking hybrid biomass sawdust as the material, carry out the simulation calibration experiment with JKR contact model based on DEM principle. The Plackett-Burman factorial experiment is carried out by Design-Expert for 10 related factors. Combined with the steepest climbing test scheme, according to the Box-Behnken experiment, the parameter calibration of the multi-response Indicators is completed. The results are as follows: the Poisson's ratio of hybrid sawdust is 0.30, the density is 399.22kg·m-3, the recovery coefficient between sawdust particles is 0.47, the rolling friction coefficient between sawdust particles is 0.39, and the parameter of surface energy density between sawdust particles (JKR) is 0.29J·m-2. Through the comparative verification experiment, it can be seen that the relative error of the repose angle is 3.41%, and the relative error of the stress-time response curve is less than 6.36%, which verifies the reliability of the calibration method, and provides a theoretical reference for the study of the constitutive characteristics of biomass materials and the densification mechanism.

Dynamic data processing method based on generalized least square method

In this paper, a time domain-processing method is introduced for the dynamic calibration based on Hopkinson bar and shock tube. With a group of accelerometer and pressure sensor data processed in our work, the algorithm for establishing dynamic mathematical model is described in detail. “Generalized least square method for special whitening filter” and the simulation results are given. It shows that this method has the characteristics of simplicity and accuracy, and is especially suitable for the establishment of difference equation model in the data processing of dynamic calibration experiment.

Ground performance tests and evaluation of RF ion microthrusters for Taiji-1 satellite

The “Taiji-1” satellite is a test satellite for the verification of those key technologies involved in the “Taiji Program in Space”, China’s space gravitational wave detection project; and the spacecraft drag-free control technology is one of its key technologies used to improve the microgravity level of spacecraft. Thus, a demand for a high-precision and continuously adjustable micronewton-level thrust has been proposed on the spacecraft micro-propulsion system. In allusion to such a task, a set of micronewton-level RF ion propulsion system was designed based on the principle of self-sustained discharge of RF plasma so as to conduct studies on the parameter optimization and engineering of RF ion thruster, and an engineering prototype of the micronewton-level continuously adjustable RF ion thruster was successfully developed to meet the design index requirements. The operating parameters have been solidified through further studies on the extreme operating conditions of the engineering prototype, and a series of ground simulation tests of space environment were successfully passed. The ground test and calibration experiment results of the micro-propulsion engineering prototype show that the engineering prototype has fully met the requirements of the Taiji-1 mission, thus having laid a solid foundation for the successful space verification of the key technologies for the “Taiji-1” satellite.

Research on Strain Transfer of Beam Sensor Based on Ansys Workbench

In this paper, the structural strain of the beam shear stress sensor is optimized, and the average strain of the strain sensor is simulated by Ansys Workbench. Firstly, the mathematic model of the beam sensor is established, and the stress and strain of the model are analyzed theoretically. Secondly, the finite element modeling of the sensor is carried out, and the finite element simulation of Ansys Workbench is carried out. The key dimensions of strain measurement are studied by parameter driven. Then the simulation results show that the effect of the production patch error on the output is quantitatively analyzed. Finally, the feasibility of mathematical model theory and finite element simulation is verified by calibration experiment.

Geodetic support for an absolute calibration experiment of a high-precision radio altimeter

Представлено геодезическое обеспечение экспериментального исследования по выполнению калибровки высокоточного радиовысотомера. Рассмотрены организационные и методические аспекты исследования, конструкция водомерного буя. Приводятся результаты вычислений высоты морской топографической поверхности и поправки за поперечный уклон геоида.

Structure Design and Calibration of INS for Distributed POS Technology

With the development of science and technology, position and orientation system (POS) technology has become an important tool for airborne earth observation system, and plays an important role in both military and civil fields. The calibration of the device directly affects the accuracy of inertial navigation. Therefore, the paper designs a compact dual mode navigation system with high and low precision, which can be used in distributed POS system. Firstly, the status of IMU calibration technology is introduced. Then it introduces the working principle, structure design and layout design of fiber optic gyroscope (FOG) combination. Finally, the calibration experiment verifies that the designed FOG combination system meets the performance index.

A Parameter Dimension Reduction-Based Estimation Approach to Enhance the Kinematic Accuracy of a Parallel Hardware-in-the-Loop Docking Simulator

SUMMARY The hardware-in-the-loop docking simulators are significant ground test equipment for aerospace projects. The fidelity of docking simulation highly depends on the accuracy performance. This paper investigates the kinematic accuracy for the developed docking simulator. A novel kinematic calibration method which can reduce the number of parameters for error modeling is presented. The principle of parameters separation is studied. A simplified error model is derived based on Taylor series. This method can contribute to the simplification of the error model, fewer measurements, and easier convergence during the parameters identification. The calibration experiment validates this method for further accuracy enhancement.