Dalian University of Technology

About: Dalian University of Technology is a education organization based out in Dalian, China. It is known for research contribution in the topics: Catalysis & Finite element method. The organization has 60890 authors who have published 71921 publications receiving 1188356 citations. The organization is also known as: Dàlián Lǐgōng Dàxué.

Design of multimaterial compliant mechanisms using level-set methods

Abstract: A monolithic compliant mechanism transmits applied forces from specified input ports to output ports by elastic deformation of its comprising materials, fulfilling required functions analogous to a rigid-body mechanism. In this paper, we propose a level-set method for designing monolithic compliant mechanisms made of multiple materials as an optimization of continuum heterogeneous structures. Central to the method is a multiphase level-set model that precisely specifies the distinct material regions and their sharp interfaces as well as the geometric boundary of the structure. Combined with the classical shape derivatives, the level-set method yields an Eulerian computational system of geometric partial differential equations, capable of performing topological changes and capturing geometric evolutions at the interface and the boundary. The proposed method is demonstrated for single-input and single-output mechanisms and illustrated with several two-dimensional examples of synthetics of multimaterial mechanisms of force inverters and gripping and clamping devices. An analysis on the formation of de facto hinges is presented based on the shape gradient information. A scheme to ensure a well-connected topology of the mechanism during the process of optimization is also presented.

Drivers and barriers to circular economy implementation: an explorative study in Pakistan’s automobile industry

Abstract: Circular economy (CE) has gained considerable attention from researchers and practitioners over the past few years because of its potential social and environmental benefits. However, limited attention has been given in the literature to explore the drivers and barriers in CE implementation in emerging and developing countries besides China. Therefore, the purpose of this paper is to identify the drivers and barriers to implementing a CE in Pakistan’s automobile manufacturing industry.,This study adopts an explorative approach to understand the drivers and barriers at the micro-level CE implementation in Pakistan’s automobile industry. The research design includes both qualitative and quantitative methods using a survey instrument and interviews to gather data. The use of the two main sources of data provides the opportunity for triangulation of the data to improve the validity of the findings, and enables greater inferences from the results.,This study shows that “profitability/market share/benefit” (30 percent), “cost reduction” (22 percent) and “business principle/concern for environment/appreciation” (19 percent) are the top three drivers. Similarly, “unawareness” (22 percent), “cost and financial constraint” (20 percent) and “lack of expertise” (17 percent) are the top three barriers in implementing CE principles in Pakistan automobiles industry.,This study considers only Pakistan automobiles industry, and the practical implications potentially limit to emerging Asian economies.,This study is the first of its kind that has investigated the drivers and barriers of CE at the organizational level in the automobile industry of Pakistan. Thus, it helps to advance the understanding of the subject matter and enables the formulation of effective policies and business strategies by practitioners for upscaling CE and sustainability.

Trajectory planning and tracking control for autonomous lane change maneuver based on the cooperative vehicle infrastructure system

Abstract: Autonomous lane change maneuver was developed using cooperative strategy.Proposed system can be potential to prevent lane change crashes and thus reducing injuries and fatalities.A trajectory planning method based on polynomial was developed.A trajectory tracking controller with global convergence ability was designed.Simulations and experimental results were presented to validate the method. Lane change maneuver is one of the most conventional behaviors in driving. Unsafe lane change maneuvers are key factor for traffic accidents and traffic congestion. For drivers' safety, comfort and convenience, advanced driver assistance systems (ADAS) are presented. The main problem discussed in this paper is the development of an autonomous lane change system. The system can be extended applied in intelligent vehicles in future. It solves two crucial issues - trajectory planning and trajectory tracking. Polynomial method was adopted for describing the trajectory planning issue. Movement of a host vehicle was abstracted into time functions. Moreover, collision detection was mapped into a parameter space by adopting infinite dynamic circles. The second issue was described by backstepping principle. According to the Lyapunov function, a tracking controller with global convergence property was verified. Both the simulations and the experimental results demonstrate the feasibility and effectiveness of the designed method for autonomous lane change.

Selective electroreduction of CO 2 to acetone by single copper atoms anchored on N-doped porous carbon

Abstract: Efficient electroreduction of CO2 to multi-carbon products is a challenging reaction because of the high energy barriers for CO2 activation and C–C coupling, which can be tuned by designing the metal centers and coordination environments of catalysts. Here, we design single atom copper encapsulated on N-doped porous carbon (Cu-SA/NPC) catalysts for reducing CO2 to multi-carbon products. Acetone is identified as the major product with a Faradaic efficiency of 36.7% and a production rate of 336.1 μg h−1. Density functional theory (DFT) calculations reveal that the coordination of Cu with four pyrrole-N atoms is the main active site and reduces the reaction free energies required for CO2 activation and C–C coupling. The energetically favorable pathways for CH3COCH3 production from CO2 reduction are proposed and the origin of selective acetone formation on Cu-SA/NPC is clarified. This work provides insight into the rational design of efficient electrocatalysts for reducing CO2 to multi-carbon products. Efficient electroreduction of CO2 to multi-carbon products is challenging. Here, the single atom Cu encapsulated on N-doped porous carbon catalysts are designed for reducing CO2 to acetone at low overpotentials and the active sites are identified as Cu coordination with four pyrrole-N atoms.