中蒙口岸发展的影响因素与策略研究——以新疆老爷庙口岸为例

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Description
自2013年中国提出“一带一路”国家倡议以来,中蒙贸易发展呈现快速发展的上升趋势,截至到2020年,中国已经连续22年一直位居蒙古最大的国际贸易伙伴国。在两国贸易发展过程中,中蒙口岸发挥着重要作用:第一,能够促进两国加工业的发展,推动物流业、旅游业等现代服务业的发展;第二,能够很大程度上弥补我国经济快速发展所需的能源资源和战略物资的需要;第三,能够有效解决蒙古国靠近中国边境省份的居民生活物资产品的供应短缺问题。然而,中蒙边境口岸发展参差不齐,急需寻找口岸发展的规律和关键因素。本文以中蒙边境15个口岸作为研究对象,通过数据分析对每个口岸的发展现状和发展定位做诊断;其次,通过专家访谈等方法挖掘影响口岸发展的关键因素,并运用AHP层次分析法对影响因素重要性排序,找出口岸发展每个阶段的关键影响因素和优先顺序,同时,我们通过灰色关联法对口岸与所在载体城市经济社会发展进行关联度分析,找出口岸发展的相关规律;最后,对于发展较弱的中蒙新疆口岸,我们以新疆老爷庙口岸为例,对标学习其他发展较快的甘其毛道和策克口岸,提出老爷庙的发展定位和策略。
Date Created
2022
Agent

Reduced order modeling with variable spatial fidelity for the linear and nonlinear dynamics of multi-bay structures

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Description
This investigation develops small-size reduced order models (ROMs) that provide an accurate prediction of the response of only part of a structure, referred to as component-centric ROMs. Four strategies to construct such ROMs are presented, the first two of which

This investigation develops small-size reduced order models (ROMs) that provide an accurate prediction of the response of only part of a structure, referred to as component-centric ROMs. Four strategies to construct such ROMs are presented, the first two of which are based on the Craig-Bampton Method and start with a set of modes for the component of interest (the β component). The response in the rest of the structure (the α component) induced by these modes is then determined and optimally represented by applying a Proper Orthogonal Decomposition strategy using Singular Value Decomposition. These first two methods are effectively basis reductions techniques of the CB basis. An approach based on the “Global - Local” Method generates the “global” modes by “averaging” the mass property over α and β comp., respectively (to extract a “coarse” model of α and β) and the “local” modes orthogonal to the “global” modes to add back necessary “information” for β. The last approach adopts as basis for the entire structure its linear modes which are dominant in the β component response. Then, the contributions of other modes in this part of the structure are approximated in terms of those of the dominant modes with close natural frequencies and similar mode shapes in the β component. In this manner, the non-dominant modal contributions are “lumped” onto the dominant ones, to reduce the number of modes for a prescribed accuracy. The four approaches are critically assessed on the structural finite element model of a 9-bay panel with the modal lumping-based method leading to the smallest sized ROMs. Therefore, it is extended to the nonlinear geometric situation and first recast as a rotation of the modal basis to achieve unobservable modes. In the linear case, these modes completely disappear from the formulation owing to orthogonality. In the nonlinear case, however, the generalized coordinates of these modes are still present in the nonlinear terms of the observable modes. A closure-type algorithm is then proposed to eliminate the unobserved generalized coordinates. This approach, its accuracy and computational savings, was demonstrated on a simple beam model and the 9-bay panel model.
Date Created
2017
Agent

Closed-form inverse kinematic solution for anthropomorphic motion in redundant robot arms

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Description
As robots are increasingly migrating out of factories and research laboratories and into our everyday lives, they should move and act in environments designed for humans. For this reason, the need of anthropomorphic movements is of utmost importance. The objective

As robots are increasingly migrating out of factories and research laboratories and into our everyday lives, they should move and act in environments designed for humans. For this reason, the need of anthropomorphic movements is of utmost importance. The objective of this thesis is to solve the inverse kinematics problem of redundant robot arms that results to anthropomorphic configurations. The swivel angle of the elbow was used as a human arm motion parameter for the robot arm to mimic. The swivel angle is defined as the rotation angle of the plane defined by the upper and lower arm around a virtual axis that connects the shoulder and wrist joints. Using kinematic data recorded from human subjects during every-day life tasks, the linear sensorimotor transformation model was validated and used to estimate the swivel angle, given the desired end-effector position. Defining the desired swivel angle simplifies the kinematic redundancy of the robot arm. The proposed method was tested with an anthropomorphic redundant robot arm and the computed motion profiles were compared to the ones of the human subjects. This thesis shows that the method computes anthropomorphic configurations for the robot arm, even if the robot arm has different link lengths than the human arm and starts its motion at random configurations.
Date Created
2013
Agent