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Electrophoretically deposited binder-free 3-D carbon/sulfur nanocomposite cathode for high-performance Li–S batteries

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Journal of Energy Chemistry 2020年第9期29卷 92-101,I0003页

作者： Sasan Ghashghaie Samson Ho-Sum Cheng Jie Fang Hafiz Khurram Shahzad Robin Lok-Wang Ma Chi-Yuen Chung department of Materials Science and engineering City University of Hong KongHong KongChina department of mechanical and Aerospace engineering The Hong Kong University of Science and TechnologyHong KongChina

In the present study,the electrophoretic deposition method was successfully applied as a binder-free and scalable approach to deposit carbonaceous nanomaterials on carbon fiber paper(CFP)for cathode applications in Li-S *** microstructural studies of the EPD-CNT film using scanning electron microscopy(SEM)revealed the formation of a crack-free and porous layer of CNTs being uniformly distributed on the CFP *** EPD:CFP/CNT/S cathode delivered a capacity around 2.2 times higher than that obtained in the absence of the EPD-CNT film(CFP/S cell)after 50 cycles and a capacity of935 mAh g^-1 after 100 cycles at 0.1 *** EPD method was then employed to fabricate layer-by-layer structures where the EPD-CNT film was decorated with carbon black *** initial capacity as well as the reversible capacity after 100 cycles was further increased by the EPD:CFP/CNT/KB/S layer-by-layer structure to 1473 and 1033 mAh g^-1,respectively,indicating effective suppression of the shuttle *** addition,the rate performance of CFP/S was improved by depositing the EPD-CNT and EPD-CNT/carbon black architectures on CFP surface,and even further enhanced through the co-deposition of CNT and Pt nanoparticles by EPD,delivering a specific capacity of around 730 mAh g^-1 at 1 ***,the cathodes fabricated by EPD were observed to outperform those made by the conventional casting method in terms of cycling performance,internal resistance,and *** difference was ascribed to the non-uniform microstructure of the Cast-CNT film,which resulted in poor interfacial connection between the CNT agglomerates,hindering uniform sulfide/sulfur deposition during *** obtained results suggested that the binder-free C/S nanocomposite cathode made by EPD is key to further enhance the specific capacity and energy density of Li-S batteries.

关键词： Electrophoretic deposition Lithium-sulfur batteries Carbon nanotubes C/S nanocomposite

Reliability-based design optimization for flexible mechanism with particle swarm optimization and advanced extremum response surface method

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Journal of Central South university 2016年第8期23卷 2001-2007页

作者：张春宜宋鲁凯费成巍郝广平刘令君 School of mechanical and Power engineering Harbin University of Science and Technology School of Computer Science and engineering Beihang University department of mechanical engineering The Hong Kong Polytechnic University

To improve the computational efficiency of the reliability-based design optimization(RBDO) of flexible mechanism, particle swarm optimization-advanced extremum response surface method(PSO-AERSM) was proposed by integrating particle swarm optimization(PSO) algorithm and advanced extremum response surface method(AERSM). Firstly, the AERSM was developed and its mathematical model was established based on artificial neural network, and the PSO algorithm was investigated. And then the RBDO model of flexible mechanism was presented based on AERSM and PSO. Finally, regarding cross-sectional area as design variable, the reliability optimization of flexible mechanism was implemented subject to reliability degree and uncertainties based on the proposed approach. The optimization results show that the cross-section sizes obviously reduce by 22.96 mm^2 while keeping reliability degree. Through the comparison of methods, it is demonstrated that the AERSM holds high computational efficiency while keeping computational precision for the RBDO of flexible mechanism, and PSO algorithm minimizes the response of the objective function. The efforts of this work provide a useful sight for the reliability optimization of flexible mechanism, and enrich and develop the reliability theory as well.

关键词： reliability-based design optimization flexible robot manipulator artificial neural network particle swarm optimization advanced extremum response surface method

Size effects on process performance and product quality in progressive microforming of shafted gears revealed by experiment and numerical modeling

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Advances in Manufacturing 2023年第1期11卷 1-20页

作者： Jun-Yuan Zheng Hui Liu Ming-Wang Fu department of mechanical engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China Research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHung HomKowloonHong KongPeople’s Republic of China

As one of the indispensable actuating components in micro-systems,the shafted microgear is in great production *** is a manufacturing process to produce microgears to meet the *** to the small geometrical size,there are uncertain process performance and product quality issues in this production *** this study,the shafted microgears were fabricated in two different scaling factors with four grain sizes using a progressively extrusion-blanking *** explore the unknown of the process,grain-based modeling was proposed and employed to simulate the entire forming *** results show that when the grains are large,the anisotropy of single grains has an obvious size effect on the forming behavior and process performance;and the produced geometries and surface quality are worsened;and the deformation load is *** deformation zones were identified in the microstructures with different hardness and distributions of stress and *** simulation by using the proposed model successfully predicted the formation of zones and revealed the inhomogeneous deformation in the forming *** undesirable geometries of microgears including material unfilling,burr and inclination were observed on the shaft and teeth of gear,and the inclination size is increased obviously with grain *** avoid the formation of inclination and material unfilling,the punch was redesigned,and a die insert was added to constraint the bottom surface of the gear *** new products had then the better forming quality.

关键词： Microforming Microprocess performance Microforming quality Size effect affected deformation behavior Die design optimization

Advanced multiple response surface method of sensitivity analysis for turbine blisk reliability with multi-physics coupling

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Chinese Journal of Aeronautics 2016年第4期29卷 962-971页

作者： Zhang Chunyi Song Lukai Fei Chengwei Lu Cheng Xie Yongmei School of mechanical and Power engineering Harbin University of Science and Technology School of Energy and Power engineering Beihang University department of mechanical engineering The Hong Kong Polytechnic University

To reasonably implement the reliability analysis and describe the significance of influencing parameters for the multi-failure modes of turbine blisk, advanced multiple response surface method (AMRSM) was proposed for multi-failure mode sensitivity analysis for reliability. The mathematical model of AMRSM was established and the basic principle of multi-failure mode sensitivity analysis for reliability with AMRSM was given. The important parameters of turbine blisk failures are obtained by the multi-failure mode sensitivity analysis of turbine blisk. Through the reliability sensitivity analyses of multiple failure modes (deformation, stress and strain) with the proposed method considering fluid-thermal-solid interaction, it is shown that the comprehensive reliability of turbine blisk is 0.9931 when the allowable deformation, stress and strain are 3.7 x 10(-3) m, 1.0023 x 10(9) Pa and 1.05 x 10(-2) m/m, respectively; the main impact factors of turbine blisk failure are gas velocity, gas temperature and rotational speed. As demonstrated in the comparison of methods (Monte Carlo (MC) method, traditional response surface method (RSM), multiple response surface method (MRSM) and AMRSM), the proposed AMRSM improves computational efficiency with acceptable computational accuracy. The efforts of this study provide the AMRSM with high precision and efficiency for multi-failure mode reliability analysis, and offer a useful insight for the reliability optimization design of multi-failure mode structure. (C) 2016 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

关键词： Advanced multiple response surface method Artificial neural network Intelligent algorithm Multi-failure mode Reliability analysis Turbine blisk

The X-structure/mechanism approach to beneficial nonlinear design in engineering

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Applied Mathematics and Mechanics(English Edition) 2022年第7期43卷 979-1000页

作者： Xingjian JING department of mechanical engineering City University of Hong KongKowloon TongHong KongChina

Nonlinearity can take an important and critical role in engineering systems,and thus cannot be simply ignored in structural design,dynamic response analysis,and parameter selection.A key issue is how to analyze and design potential nonlinearities introduced to or inherent in a system under *** is a must-do task in many practical applications involving vibration control,energy harvesting,sensor systems,robotic technology,*** paper presents an up-to-date review on a cutting-edge method for nonlinearity manipulation and employment developed in recent several years,named as the X-structure/mechanism *** method is inspired from animal leg/limb skeletons,and can provide passive low-cost high-efficiency adjustable and beneficial nonlinear stiffness(high static&ultra-low dynamic),nonlinear damping(dependent on resonant frequency and/or relative vibration displacement),and nonlinear inertia(low static&high dynamic)individually or *** X-structure/mechanism is a generic and basic structure/mechanism,representing a class of structures/mechanisms which can achieve beneficial geometric nonlinearity during structural deflection or mechanism motion,can be flexibly realized through commonly-used mechanical components,and have many different forms(with a basic unit taking a shape like X/K/Z/S/V,quadrilateral,diamond,polygon,etc.).Importantly,all variant structures/mechanisms may share similar geometric nonlinearities and thus exhibit similar nonlinear stiffness/damping properties in ***,they are generally flexible in design and easy to *** paper systematically reviews the research background,motivation,essential bio-inspired ideas,advantages of this novel method,the beneficial nonlinear properties in stiffness,damping,and inertia,and the potential applications,and ends with some remarks and conclusions.

关键词： nonlinear stiffness nonlinear damping nonlinear inertia vibration

Semi-global leader-following consensus-based formation flight of unmanned aerial vehicles

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Chinese Journal of Aeronautics 2022年第1期35卷 31-43页

作者： Panpan ZHOU Ben M.CHEN department of mechanical ami Automation engineering The Chinese University of Hong KongHong KongChina

In this paper,we investigate a formation control problem of multi-agent systems(specifically a group of unmanned aerial vehicles)based on a semi-global leader-following consensus approach with both the leader and the followers subject to input *** the low gain feedback design technique,a distributed static control protocol and a distributed adaptive control protocol are *** former solves the problem under an assumption that the communication network is undirected,and it depends on the global information of the *** the latter,we relax the undirected graph to directed ***,an adaptive updating gain is designed to avoid using the global information of the communication *** is shown that the consensus protocols can solve the semi-global leader-following consensus problem if the leader agent is globally *** results are verified successfully by both simulation and real flight tests.

关键词： Consensus Formation flying Input saturation Low gain feedback Multi-agent systems Unmanned aerial vehicles

New challenges for optimal design of nearly/net zero energy buildings under post-occupancy performance-based design standards and a risk-benefit based solution

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Building Simulation 2022年第5期15卷 685-698页

作者： Hangxin Li Shengwei Wang department of Building Environment and Energy engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina Research Institute for Smart Energy The Hong Kong Polytechnic UniversityKowloonHong KongChina

One of the challenges in construction of nearly and net ZEBs is how to truly achieve the nearly and net energy goals after building *** building design standards and practices are mostly based on design performance evaluation,but practices show that many designed nearly/net ZEBs failed to achieve the energy goals after building *** facilitate the practical achievement of nearly and net ZEBs,recently most of the newly-released ZEB design standards have turned to post-occupancy performance evaluation,posing great challenges to nearly and net ZEB ***,the detailed challenges have not be comprehensively investigated,and effective optimal design methods which can facilitate the achievement of nearly and net ZEBs under these standards are still *** this study,new challenges of nearly and net ZEB design under the post-occupancy performance-based design standards are fully investigated,and a risk-benefit based optimal design method is proposed to facilitate the achievement of nearly and net ZEBs under these *** newly-released ZEB standard in China is taken as an example to investigate the challenges and test the proposed *** show that nearly and net ZEBs designed using conventional design method have high risk in achieving energy goals under these standards due to high risk in satisfying the requirement regarding non-renewable primary energy consumption after building *** proposed design method is effective to facilitate achieving energy goals under these standards based on the risk that decision-makers would like to take.

关键词： zero energy building optimal design post-occupancy performance ZEB standard uncertainty analysis risk-benefit assessment

Machine learning for advanced energy materials

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Energy and AI 2021年第1期3卷 22-48页

作者： Yun Liu Oladapo Christopher Esan Zhefei Pan Liang An department of mechanical engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina

The screening of advanced materials coupled with the modeling of their quantitative structural-activity relation-ships has recently become one of the hot and trending topics in energy materials due to the diverse challenges,including low success probabilities,high time consumption,and high computational cost associated with the traditional methods of developing energy *** this,new research concepts and technologies to promote the research and development of energy materials become *** latest advancements in ar-tificial intelligence and machine learning have therefore increased the expectation that data-driven materials science would revolutionize scientific discoveries towards providing new paradigms for the development of en-ergy ***,the current advances in data-driven materials engineering also demonstrate that the application of machine learning technology would not only significantly facilitate the design and development of advanced energy materials but also enhance their discovery and *** this article,the importance and necessity of developing new energy materials towards contributing to the global carbon neutrality are presented.A comprehensive introduction to the fundamentals of machine learning is also provided,including open-source databases,feature engineering,machine learning algorithms,and analysis of machine learning ***,the latest progress in data-driven materials science and engineering,including alkaline ion battery materials,pho-tovoltaic materials,catalytic materials,and carbon dioxide capture materials,is ***,relevant clues to the successful applications of machine learning and the remaining challenges towards the development of advanced energy materials are highlighted.

关键词： Energy materials Artificial intelligence Machine learning Data-driven materials science and engineering Prediction of materials properties Design and discovery of energy materials

Modeling the collapse of the Plasco *** I:Reconstruction of fire

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Building Simulation 2022年第4期15卷 583-596页

作者： Aatif Ali Khan Ramakanth Veera Venkata Domada Xinyan Huang Mustesin Ali Khan Asif Usmani department of Building Services engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina Research Institute for Sustainable Urban Development The Hong Kong Polytechnic UniversityKowloonHong KongChina

In recent years,fires in tall buildings have become more frequent,which costs billions of dollars each year and the loss of many human *** facade fire in the Grenfell tower made the structure uninhabitable,and the collapse of the three World Trade Center(WTC)towers is the total structural failure caused by *** such events,no well-defined methodology exists to reconstruct both fire and structural behaviors and carrys out the forensic investigation of a building *** Part I paper collects the evidence of the Plasco Building fire and generates a coherent timeline to reconstruct the fire *** vertical and horizontal fire spread of the building is reconstructed using computational fluid dynamics(CFD)fire modeling and calibrated against the evidence *** spatio-temporal temperature history from the fire modeling provides realistic fire scenarios to simulate the structural *** fire simulation results are used as boundary conditions to be transferred to a finite element analysis tool for a detailed structural analysis to determine the likely collapse mechanism of the Plasco Building in Part *** methodology presented in this paper to reconstruct the fire can also guide the structural fire safety engineers to improve the building fire-safety and life-safety strategies.

关键词： building fire safety high-rise buildings fire investigation fire modeling structure failure