http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Dynamic model-based back-stepping control design for-trajectory tracking of seabed tracked vehicles
Hong Xiong,Yuxiang Chen,Yuxiao Li,Hong Zhu,Chunliang Yu,Jingguo Zhang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
Tracked vehicles are widely used as seabed production tools to ensure a stable motion on soft sediments. However, the slippage resulted from the complex nonlinear trackterrain interaction while trajectory tracking causes problems for precisely predicting the motion. Accordingly, a “proper” motion control method is necessitated. This work proposes a novel dynamic modeling approach and motion control method for seabed tracked vehicles under nonholonomic constraints, with the inclusion of the effects of the bulldozing resistance, compaction resistance, water resistance, and the direction and velocity of the current. The backstepping control based on a model-based proportional-integral-derivative three degrees-offreedom method is applied in the controller, and its stability is proven by Lyapunov theory. The effectiveness and accuracy of the method in controlling seabed tracked vehicles are validated by simulation examples.
Creep Properties of a Nickel-Based Single Crystal Superalloy with Low Density
Yuling Du,Zihao Tan,Yanhong Yang,Xinguang Wang,Yizhou Zhou,Jingguo Li,Xiaofeng Sun 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12
A novel nickel-based single crystal superalloy with low density had been designed and the creep deformation mechanismsof the experiment alloy under two conditions (1050 °C/200 MPa and 1100 °C/137 MPa) had been systematically discussed. The topological inversion had been observed after fracture under the above two conditions. The effects of temperature andstress on creep life of the experiment alloy had been found no significant difference under the two conditions. It was indicatedthat the small decrease in temperature exerted limited influence on the creep behaviors of single crystal superalloys in therange of high temperature.
Jing Guo,Zhiming Wang,Xuesheng Li,Chaoyang Sun,Erdong Gao,Hongbo Li 대한치과보철학회 2016 The Journal of Advanced Prosthodontics Vol.8 No.6
PURPOSE This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to 45° oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (α=.05). RESULTS The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.