基于运动数据的仿生压曲模型设计方法

针对人工踩曲用工数量巨大、生产效率低下而单纯的机械式制曲方法不能保证曲块质量的问题,对制曲进行需求分析,研究了仿生压曲机构三维模型设计方法,提出了仿生压曲机构动作设计中人工踩曲运动数据的提取与分析。运用运动重定向技术得到人体三维简化模型的BVH格式数据。然后对数据进行运动学分析求解,生成人工踩曲运动轨迹,为仿生压曲机构的研发提供理论支撑。

Impact of nonlinear processes on formation of the Kuroshio large meander path in a barotropic inflow-outflow model

Based on a barotropic inflow-outflow model,we examine the formation of the Kuroshio large meander(LM) using conditional nonlinear optimal perturbation(CNOP) method.Both linear and nonlinear evolutions of such perturbations obtained by this method are investigated.The results show that the nonlinear evolution can result in the Kuroshio transition from a straight to LM path,whereas the linear evolution cannot.This implies that nonlinearity plays an important role in the formation of the Kuroshio LM path.The nonlinearity exists as advection in the evolution equations of the perturbation derived from the barotropic inflow-outflow model,namely the nonlinear advection of the perturbation by the perturbation(NAPP).By examining the role of this nonlinearity,we find that the NAPP tends to move the cyclonic eddy induced by the CNOP-type perturbation westward.Together with the beta effect,this offsets part of the eastward advection caused by the interaction between the perturbation and the background flow.Hence,the eastward movement of the cyclonic eddy is significantly weakened,effectively causing the eddy to develop.The sufficient evolution of this cyclonic eddy leads to the formation of the Kuroshio LM.

Rate decline analysis of multiple fractured horizontal well in shale reservoir with triple continuum

Multiple fractured horizontal well(MFHW) is widely applied in the development of shale gas. To investigate the gas flow characteristics in shale, based on a new dual mechanism triple continuum model, an analytical solution for MFHW surrounded by stimulated reservoir volume(SRV) was presented. Pressure and pressure derivative curves were used to identify the characteristics of flow regimes in shale. Blasingame type curves were established to evaluate the effects of sensitive parameters on rate decline curves, which indicates that the whole flow regimes could be divided into transient flow, feeding flow, and pseudo steady state flow. In feeding flow regime, the production of gas well is gradually fed by adsorbed gases in sub matrix, and free gases in matrix. The proportion of different gas sources to well production is determined by such parameters as storability ratios of triple continuum, transmissibility coefficients controlled by dual flow mechanism and fracture conductivity.

A 3D bounding surface model for rockfill materials

A 3D bounding surface model is established for rockfill materials,which can be applied to appropriately predict the deformation and the stabilization of rockfill dams.Firstly,an associated plastic flow rule for rockfill materials is investigated based on the elaborate data from the large-style triaxial compression tests and the true triaxial tests.Secondly,the constitutive equations of the 3D bounding surface model are established by several steps.These steps include the bounding surface incorporating the general nonlinear strength criterion,stress-dilatancy equations,the evolution of the bounding surface and the bounding surface plasticity.Finally,the 3D bounding surface model is used to predict the mechanical behaviors of rockfill materials from the large-style triaxial compression tests and the true triaxial tests.Consequently,the proposed 3D bounding surface model can well capture such behaviors of rockfill materials as the strain hardening,the post-peak strain softening,and the volumetric strain contraction and expansion in both two-and three-dimensional stress spaces.

A curved surface solar radiation pressure force model for solar sail deformation

A precise force model is of vital importance for dynamics and control of solar sails. Among various factors, deviations from the ideal flat sails, elastic deformations of the sails, are really important as most solar sails are large flexible membranes. In this study, the deformed sails are modeled as smooth curved surfaces and a general total force model (GTFM) for the deformed sails is proposed. Various simplified versions of this GTFM are also derived for the symmetric deformation cases. Furthermore, differences between the ideal force models and our precise GTFM are investigated. The numerical results demonstrate that both the previous ideal reflected model and flat optical model are not as satisfactory as claimed before, by contrast with the actual dynamics from the GTFM. Thus this work paves the way for sail craft's precise navigation where exact forces are needed.