In this article, considering the characteristics of nonlinearity, time-variables, and disturbance in hydraulic roll-bending system, a generalized predictive control scheme based on time series prediction error compensation was proposed. A time series prediction model was used to compensate the future sequence error, which not only made the system have strong anti-interference and robustness, but also improved target tracking accuracy and stability of the system. The control algorithm was simplified by introducing control increment attenuation factors into the predictive control model, and thus, system response speed and real-time performance were improved obviously. The results obtained from simulation validated the feasibility and effectiveness of the algorithm.
The use of lightweight sheets such as carbon fiber reinforced composites (CFRP), magnesium alloys, and aluminum alloys is of great significance to realize the lightweight of automobiles. However, the differences between the sheets make the joining processes of dissimilar sheets a great challenge. A pre-holed screw-drilling riveting (PH-SDR) process is proposed based on a study of existing joining processes, the rivet with threads is riveted into the sheets by rotating, and the effective joining between the sheets is achieved by embedding the sheets into the rivet threads. The joint strength of the PH-SDR and self-piercing riveting (SPR) was compared through the lap-shear test. It was found that in the case of 1 mm Al6061-T6 + 2 mm AZ31B, the strength of the PH-SDR joint was 3.09 kN, which is 30.9% higher than the SPR of 2.36 kN. In the case of 2 mm CFRP + 2 mm Al6061-T6, when the spindle speed was 600 rpm, the strength of 5.43 kN and the energy absorption of 20.3 J were obtained for the PH-SDR joint, which is 51.2% and 89.7% higher than the optimal SPR joint. The results show that the proposed PH-SDR process provides a feasible solution for the joining of dissimilar lightweight sheets.
Height is an important indicator of rice growth condition and phenological period. The Polarimetric SAR Interferometry (PolInSAR) has proven a valuable technique for providing structural metrics of vegetation. Anechoic chamber experiments, allowing a high flexibility in the configuration of operating parameters, such as frequency and baseline, is the most convenient and feasible way to study the potential of PolInSAR in rice height retrieval. In this study, the first PolInSAR measurements of a recently built anechoic chamber, The Laboratory of Target Microwave Properties (LAMP), were presented and analyzed versus frequency and baseline, and rice height was retrieved using the measurement data. The results confirm that LAMP has the ability of PolInSAR, and the height of rice in milk stage is retrieved more precisely in the frequency range of 2.5 to 4.7GHz, when the baseline is 0.5°. The results are expected to contribute to studying and to defining the operation modes for future SAR missions.
Europe made the earliest contribution to modern civilisation and modernisation of Europe has long drawn attention from the academic world. This article conducts an investigation into the origin and historical process of modern Europe from a macroscopic perspective, in order to develop better understanding of the connection between European history and modern civilisation. It first illustrates the historical background against which modern Europe originated. Then it interprets the historical process of Europe’s modernisation with respect to economy, culture, politics, and technology. The outcomes and significance of Europe’s modernisation are discussed at the end. This study also reveals obvious continuity of European history and its impact on the modern world.
Europe made the earliest contribution to modern civilisation and modernisation of Europe has long drawn attention from the academic world. This article conducts an investigation into the origin and historical process of modern Europe from a macroscopic perspective, in order to develop better understanding of the connection between European history and modern civilisation. It first illustrates the historical background against which modern Europe originated. Then it interprets the historical process of Europe’s modernisation in respect to economy, culture, politics, and technology. The outcomes and significance of Europe’s modernisation are discussed at the end. This study also reveals obvious continuity of European history and its impact on the modern world.
Based on new high-resolution seismic profiles,a opposite thrust structural deformation features for late Cenozoic Wushi Sag of northwestern Tarim Basin,northwestern China is proposed in this paper.To the north of the sag is the Southern Tianshan thrust system,of which the faults thrust from the north to the south,the main thrust fault is Shenmuyuan fault,and the front thrust fault is Xiatagake fault;To the south of the sag is the Wensu uplift backthrust system,of which the faults thrust from the south to the north,and the main thrust fault is Gumubiezi fault.Moreover,there develops one detached fault along the gypsum layer on me bottom of Neogene or Paleogene because of the opposite thrust of basement.As a result,the Cenozoic in Wushi area fold a down.Thus,the Wushi sag is in fact a syncline,and the structural deformation is at all different below or on the detached fault above.The structural deformation,happened mainly in the sedimentary period of Kuche Formation of Neogene,and became stronger in the Quaternary,and is the result of collision between India and Asia continents,which has controlling influence on structural trap and petroleum migration of late Cenozoic.
Abstract Petroleum geologists have debated whether the hydrocarbons from Jurassic coal measures are derived from the coals, carbonaceous mudstones or coal‐measure mudstones in the Turpan Basin. Based on the geochemistry analysis of the 20 crude oils and 40 source rocks from the Turpan Basin, some data have been obtained as follows: carbon preference index and methylphenanthrene index of the Jurassic oils are 1.16–1.45 and 0.28–0.80, and the ααα C 29 sterane 20S/(20S+20R) and C 29 sterane ββ/(ββ+αα) are 0.44–0.51 and 0.4–0.54 respectively, which show the normal maturity of oils; the vitrinite reflectance of the source rocks from the Xishanyao to Badaowan Formations range from 0.47% to 0.97%, which indicate immature to mature thermal evolutionary stage and sufficient conditions for generating mass mature oil. The effect of hydrocarbon expulsion should be considered when studying the source of coal‐derived oil by using Biomarkers. Biomarkers in the Jurassic oils from the basin are similar to those in the coals and carbonaceous mudstones, with a strong predominant content of pristane, relatively high ratio of C 15 /C 16 sesquiterpenoids (>1), a relatively high content of low carbon number tricyclic terpanes and C 24 tetracyclic terpane, little gammacerane and C 29 Ts detected, an absolute predominant content of C 29 sterane and a relatively high content of diasterane. However, the opposite characteristics are shown in mudstones, with an approximately equal content of pristane and phytane, relatively low ratio of C 15 /C 16 sesquiterpenoids (<1), a relatively high content of high carbon number tricyclic terpanes and a low content of C 24 tetracyclic terpane, peaks of gammacerane and C 29 Ts detected obviously and an increasing C 27 sterane content All of these characteristics identify the coals and carbonaceous mudstones as the possible major oil source rocks in this area, and they were formed in the stronger oxidizing environment with shallower water than mudstones.
Abstract Tool parameters play a vital role in the mechanical interlock formation during the flat clinching process, to understand the influence of tool parameters on the interlock formation, the finite element software DEFORM-2D was used to build the numerical model of the flat clinching process, and the numerical model was verified by the experiment. The influences of the punch radius, punch fillet radius, and blank holder radius on the interlock formation of the clinched joint were investigated using the numerical model. Then, the relationship between the punch radius and blank holder radius was studied. The results showed that the interlock gradually increases with the increase of the blank holder radius, after that, the interlock begins to decrease. To maximize the interlock, the punch radius and the blank holder radius should be increased simultaneously. It can be concluded that the blank holder radius and the punch radius should keep in a linear relationship when designing the geometric dimensions of the flat clinch tools, which can promote the application of flat clinching process in car body manufacturing.
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