Grid fin translation mechanism is the key actuator of trajectory and attitude control in reentry flight of the reusable launch vehicle. The kinetic characteristic of translation mechanism is investigated experimentally. An experimental device and experimental schemes comprise position test, transient state test and frequency test are set up. The linear displacement of servo piston rod and the angle displacement of rudder shaft are measured by the displacement sensors. Firstly, the cause of linear displacement abrupt change in position test and angle displacement vibration in transient state test is studied. Furthermore, small shaft turning angle frequency test in low, mid and high frequency are tested and the angle displacement signal delay are comparativly analyzed. The clearances in kinematic pairs are considered as the important affecting factor of kinetic characteristic of translation mechanism and its influencing mechanism is preliminarily proposed. The results provide research object and experimental fundament for farther dynamic analysis and optimal design of transmission mechanism.
An experimental apparatus was designed to test the pivoting friction moment of annular friction disc under either constant normal force and variable normal force. The experimental results demonstrated the applicability of the classical pivoting friction model under the continuous variable normal contact force, and showed that the rotary velocity affects the properties of the pivoting friction. By considering the Stribeck effect of the local friction at a contact point, a theoretical model was proposed for the pivoting friction. Good agreement between proposed theoretical and experimental results sheds light on the physical mechanism underlying the pivoting friction.
Aimed at providing efficient training data for neural translation quality estimation model, a pseudo data construction method for target dataset is proposed, the model is trained by two stage model training method: pre training based on pseudo data and fine tuning. The experimental design of different pseudo data scale is carried out. The experiment results show that the machine translation quality estimation model trained by the pseudo data has significantly improved in the correlation between the scores given by human and the artificial scores.
The oil geology feature of Vienna Basin was summarized and potential of exploration was discussed by analysising the strata of Vienna Basin and fracture development characteristics. Vienna Basin is a pull-apart basin located between the East Alps and West Carpathian. Its basement is composed of the Hercynian Bohemian Massif and Paleozoic and Mesozoic strata. The tectonic evolution can be divided into three stages, including Jurassic extensional rifting, Cretaceous-Early Miocene over-thrusting and Middle Miocene pull-parting stage. There are three structural lays from top to bottom, Jurassic-Cretaceous autochthonous, Permian-Paleogene allochthonous Alpine nappes and Neogene sediments. There are two sets of source rocks: the upper Jurassic marls and Paleogene shale, among which, the Upper Jurassic Kimmeridgian Malmian marls are considered to be the major source rocks. Reservoirs occur at various horizons from Triassic to Neogene Miocene strata, among which, the most important reservoirs are Miocene sandstones that deposit in shallow-water delta environment and contain 76% of all reserves, and the minor reservoirs are the Triassic dolosparite. Neogene shales provide the regional top-seal. After evaluation, it is considered that Mesozoic allochthonous napps (flysch turbidite and Triassic dolomite) and Mesozoic autochthonous succession (the second and the third structural layer) are the most prospective for exploration.
The Qingcaoshan granitic pluton, located in the Zhapu-Duobuza magmatic arc in southern Qiangtang, consists of granite porphyry and quartz monzonitic porphyry. However, the age and genesis are not studied due to absence of geochemical and geochronological data. The weighted average 206Pb/238U age of 122±1 Ma (MSWD=3.9) for quartz monzonitic porphyry and 114.6±1.2 Ma (MSWD=1.1) for granite porphyry is present by LA-ICPMS and SHRIMP zircon U-Pb dating. The intrusion have minor muscovite and cordierite, no hornblende. The granitic pluton is characterized by enriched Al (A12O3: 14.81%-15.86%), depleted Ca (CaO: 1.10%-2.44%), and high content of alkali (K2O+Na2O: 6.86%-8.80%). Father more, it is also characterized by ASI of 1.1 (A/CNK: 1.06-1.20), corundum (1.20%-2.86%) and absence of diopside showed through CIPW calculation, which are indicative of peraluminous sub-alkaline S-type graniten. The intrusive rock is relatively enriched in large ion lithophile elements (Rb, Th, U, K, La, Ce) and depleted in high field strength elements (Ta, Nb, P, Ti, Y), and exhibits LREE-enriched ((La/Yb)N: 3.24-16.20) with right-inclined REE distribution patterns. A synthesis of all these characteristics indicates that the Qingcaoshan granitic pluton was probably derived from partial melting of greywacke components in the upper crust as a result of norward subduction of the Bangong Co-Nujiang oceanic crust towards the Qiangtang block.
Based on the observational atmospheric turbulent data obtained from 255-m tower in Tianjin, the characteristics of different atmospheric variables and turbulent transfer during the fog periods were studied. The results show that before the fog, there exists high humidity, and the height of inversion reaches to 100 m. The inversion of radiation fog is stronger than that of the advection fog. During the fog, the inversion continues strengthening. With the lifting of inversion, the neutral and unstable stratification occurres which means the dissipation of fogs. Meanwhile, the development of inversion in the radiation fog is more obvious than that in advection fogs, the height of radiation fogs is lower than that of advection fogs, and the main reasons for the dissipation of radiation and advection fogs are temperature and wind speed, respectively. The stratification is changed by the fog period, resulting in an unstable nocturnal atmosphere. The vertical transfer is weak and the horizontal transfer strengthened in the later stage. The increasing in the ratio of mean kinetic energy to turbulent kinetic energy before the fog can be treated as the signal of the occurrence of fog and the decreasing marks the dissipation of fog.
A new numerical method based on LZB is proposed for nonsmooth dynamics on astronautics separation device in guided stage. Using Euler-Lagrange equations and the LZB method, the general calculating framework describing the whole dynamical motion including contact, collision with friction is established. Compared with FEM simulation time, numerical simulation implies that this method is valid.
