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Layered niobium carbide enabling excellent kinetics and cycling stability of Li-Mg-B-H hydrogen storage material Layered niobium carbide enabling excellent kinetics

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Rare Metals 2024年第3期43卷 1153-1166页

作者： Li-Wen Lu Hui Luo Guang-Xu Li Yun Li Xin-Hua wang Cun-Ke Huang Zhi-QiangLan Wen-Zheng Zhou Jin Guo Mohammad ismail Hai-Zhen Liu Guangxi Novel Battery Materials Research Center of Engineering Technology Guangxi Colleges and Universities Key Laboratory of Blue Energy and Systems IntegrationSchool of Physical Science and TechnologyGuangxi UniversityNanning530004China State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures Nanning530004China School of Mechanical and Electrical Engineering Quzhou College of TechnologyQuzhou324000China Department of Materials Science and Engineering Zhejiang UniversityHangzhou310027China Faculty of Ocean Engineering Technology and informatics Universiti Malaysia Terengganu21030Kuala NerusTerengganuMalaysia Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjin300071China

The Li-Mg-B-H composite(2LiBH_(4)+MgH_(2))has a high capacity of 11.4 wt%as a hydrogen storage ***,the slow kinetics and poor cycling stability severely restrict its practical *** this work,a layered Nb_(2)C MXene was first synthesized and then introduced to tailor the kinetics and cycling stability of the Li-Mg-B-H *** milled 2lih+MgB_(2)composites were initially hydrogenated to obtain the 2LiBH_(4)+MgH_(2)*** 2LiBH_(4)+MgH_(2)+5wt%Nb_(2)C can release 9.0 wt%H_(2)in 30 min at 400℃,while it is only 2.7 wt%for the undoped 2LiBH_(4)+MgH_(2).The dehydrogenation activation energies of MgH_(2)and LiBH_(4)are 123 and 154 kJ·mol^(-1)respectively for the 5 wt%Nb_(2)C-doped composite,lower than the undoped composite(164 and 165 kJ·mol^(-1)).The 2LiBH_(4)+MgH_(2)+5 wt%Nb_(2)C possesses excellent cycling stability,with the reversible capacity only slightly reduced from 9.4 wt%for the 1st cycle to 9.3 wt%for the 20th ***_(2)C keeps stable in the composite and acts as an efficient catalyst for the Li-Mg-B-H *** is believed that both the layered structure and the active Nb element contribu te to the enhanced hydrogen storage performances of the Li-Mg-B-H *** work confirms that the Nb_(2)C MXene with layered stru cture has a significant enhancing impact on the Li-Mg-B-H hydrogen storage materials,which is different from the bulk NbC.

关键词： Hydrogen storage Lithium borohydride Magnesium hydride Nb_(2)C MXene

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A floating point conversion algorithm for mixed precision computations

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第9期13卷 711-718页

作者： Choon lih HOO Sallehuddin Mohamed HARiS Nik Abdullah Nik MOHAMED Department of Mechanical and Materials Engineering Universiti Kebangsaan MalaysiaUKM Bangi 43600Malaysia

The floating point number is the most commonly used real number representation for digital computations due to its high precision characteristics. it is used on computers and on single chip applications such as DSP chips. Double precision (64-bit) representations allow for a wider range of real numbers to be denoted. However, single precision (32-bit) operations are more efficient. Recently, there has been an increasing interest in mixed precision computations which take advantage of single precision efficiency on 64-bit numbers. This calls for the ability to interchange between the two formats. in this paper, an algorithm that converts floating point numbers from 64- to 32-bit representations is presented. The algorithm was implemented as a Verilog code and tested on field programmable gate array (FPGA) using the Quartus ii DE2 board and Agilent 16821A portable logic analyzer. Results indicate that the algorithm can perform the conversion reliably and accurately within a constant execution time of 25 ns with a 20 MHz clock frequency regardless of the number being converted.

关键词： Double precision Single precision FPGA Verilog HooHar algorithm

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Microcellular injection molding process for producing lightweight thermoplastic polyurethane with customizable properties

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Frontiers of Mechanical Engineering 2018年第1期13卷 96-106页

作者： Thomas ELLiNGHAM Hrishikesh KHARBAS Mihai MANiTiU Guenter SCHOLZ lih-Sheng TURNG Department of Mechanical Engineering University of Wisconsin-Madison Madison WI 53706 USA Wisconsin institute for Discovery University of Wiseonsin-MadisonMadison WI 53715 USA BASF Corporation Wyandotte MI 48192 USA

A three-stage molding process involving microcellular injection molding with core retraction and an ＂out-of-mold＂ expansion was developed to manufacture thermoplastic polyurethane into lightweight foams of varying local densities, microstructures, and mechanical properties in the same microcellular injection molded part. Two stages of cavity expansion through sequential core retractions and a third expansion in a separate mold at an elevated temperature were carried out. The densities varied from 0.25 to 0.42 g/cm3 （77% to 62% weight reduction）. The mechanical properties varied as well Cyclic com- pressive strengths and hysteresis loss ratios, together with the microstructures, were characterized and reported.

关键词： thermoplastic polyurethane microcellularinjection molding cavity expansion compressive strength,hysteresis loss ratio

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improving Polylactide Toughness by Plasticizing with Low Molecular Weight Polylactide-Poly(Butylene Succinate)Copolymer

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Journal of Renewable Materials 2021年第7期9卷 1267-1281页

作者： Yottha Srithep Onpreeya Veang-in Dutchanee Pholharn lih-Sheng Turng John Morris Manufacturing and Materials Research Unit Department of Manufacturing EngineeringFaculty of EngineeringMahasarakham UniversityMahasarakham44150Thailand Department of Chemistry Faculty of Science and TechnologyRajabhat Maha Sarakham UniversityMahasarakham44000Thailand Polymer Engineering Center Department of Mechanical EngineeringUniversity of Wisconsin-MadisonMadison53705USA King Mongkut institute of Technology Ladkrabang Bangkok10520Thailand

A low-molecular-weight polylactide-poly(butylene succinate)(PLA-PBS)copolymer was synthesized and incorporated into polylactide(PLA)as a novel toughening agent by solvent *** copolymer had the same chemical structure and function as PLA and it was used as a plasticizer to *** copolymer was blended with PLA at a weight ratio from 2 to 10 wt%.Phase separation between PLA and PLA-PBS was not observed from their scanning electron microscopy(SEM)images and the crystal structure of PLA almost remained unchanged based on the X-ray diffraction(XRD)*** melt flow index(MFi)of the blends was higher as the amount of PLA-PBS increased,indicating that the block copolymer did improve the mobility of the PLA ***,tensile tests revealed that PLA with greater PLA-PBS copolymer exhibited higher elongation at break and it reached the maximum at 8 wt%of PLA-PBS in PLA,which was around 6 times higher than that of pure ***,the glass transition temperature,measured by differential scanning calorimetry(DSC),markedly decreased with an increasing amount of the copolymer as it decreased from 61.2℃ for pure PLA to 41.3℃when it was blended with 10 wt%PLA-PBS ***,the PLA-PBS copolymer was shown to be a promising plasticizer for fully biobased and toughened PLA.

关键词： Polylactide poly(butylene succinate) low molecular weight copolymer biodegradability plasticizer

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Reinforcement learning for whole-building HVAC control and demand response

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能源与人工智能(英文) 2020年第2期2卷 15-32页

作者： Donald Azuatalam Wee-lih Lee Frits de Nijs Ariel Liebman Department of Data Science and Ai Faculty of ITMonash UniversityClaytonVIC 3168Australia Monash eResearch Centre Monash UniversityClaytonVIC 3168Australia Monash Energy institute Monash UniversityClaytonVIC 3168Australia

This paper proposes a novel reinforcement learning(RL)architecture for the efficient scheduling and control of the heating,ventilation and air conditioning(HVAC)system in a commercial building while harnessing its de-mand response(DR)*** advances in automated building management systems,this can be achieved seamlessly by a smart autonomous RL agent which takes the best action,for example,a change in HVAC temper-ature set point,necessary to change the electricity usage pattern of a building in response to demand response signals,and with minimal thermal comfort impact to *** research in this area has tackled only individual aspects of the problem using ***,due to the challenges in implementing demand response with whole-building models,simpler analytical models which poorly capture reality have been used *** where whole-building models are applied,RL is used for HVAC control mainly to achieve energy efficiency goals while demand response is ***,in this research,we implement a holistic framework by designing an efficient RL controller for a whole-building model which learns to optimise and control the HVAC system for improved energy efficiency and thermal comfort levels in addition to achieving demand response *** simulation results show that by applying reinforcement learning for normal HVAC operation,a maximum weekly energy reduction of up to 22%can be achieved compared to a handcrafted baseline ***,by employing a DR-aware RL controller during demand response periods,average power reductions or increases of up to 50%can be achieved on a weekly basis compared to the default RL controller,while keeping occupant thermal comfort levels within acceptable bounds.

关键词： Demand response Reinforcement learning Whole-building HVAC control Distributed energy resources Optimal HVAC energy scheduling

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Fabrication of Highly Porous interconnected Three-dimensional Scaffolds with Micro-channels

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Chinese Journal of Polymer Science 2014年第7期32卷 864-870页

作者： Zhi-xiang Cui Hai-bin Zhao Yi-yan Peng Yottha Srithep lih-Sheng Turng 申长雨 Fujian University of Technology Shandong University University of Wisconsin-Madison Zhengzhou University

A novel highly porous 3-D poly（e-caprolactone）（PCL） scaffold with micro-channels was fabricated by injection molding and diluent acetic acids leaching technologies. in this study, the chitosan fiber was employed to form the microchannel in PCL matrix. The morphology, porosity and mechanical properties of the scaffolds were studied and calculated. it was found that the larger the content of chitosan fiber is, the higher the porosity would be, due to the volumetric expansion of chitosan fiber in PCL matrix during it being leached. in addition, the less the content of chitosan fiber is, the higher the compressive modulus would be.

关键词： injection molding Micro-channel Chitosan fiber Poly(ε-caprolactone) scaffold.

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Experiment and simulation of foaming injection molding of polypropylene/nano-calcium carbonate composites by supercritical carbon dioxide

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Chinese Journal of Chemical Engineering 2016年第1期24卷 180-189页

作者： Zhenhao Xi Jie Chen Tao Liu Ling Zhao lih-Sheng Turng State Key Laboratory of Chemical Engineering East China University of Science and Technology Department of Mechanical Engineering University of Wisconsin–Madison

Microcellular injection molding of neat isotactic polypropylene(iPP) and isotactic polypropylene/nano-calcium carbonate composites(i PP/nano-CaCO_3) was performed using supercritical carbon dioxide as the physical blowing agent. The influences of filler content and operating conditions on microstructure morphology of i PP and i PP/nano-CaCO_3 microcellular samples were studied systematically. The results showed the bubble size of the microcellular samples could be effectively decreased while the cell density increased for i PP/nano-CaCO_3 composites, especially at high CO_2 concentration and back pressure, low mold temperature and injection speed, and high filler content. Then Moldex 3D was applied to simulate the microcellular injection molding process, with the application of the measured ScCO_2 solubility and diffusion data for i PP and i PP/nano-Ca CO_3 composites respectively. For neat i PP, the simulated bubble size and density distribution in the center section of tensile bars showed a good agreement with the experimental values. However, for i PP/nano-CaCO_3 composites, the correction factor for nucleation activation energy F and the pre-exponential factor of nucleation rate f_0 were obtained by nonlinear regression on the experimental bubble size and density distribution. The parameters F and f_0 can be used to predict the microcellular injection molding process for i PP/nano-CaCO_3 composites by Moldex 3D.

关键词： Microcellular injection molding isotactic polypropylene/nano-calcium carbonate Cell morphology Nucleation activation energy Numerical simulation

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Fabrication of scaffolds in tissue engineering： A review

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Frontiers of Mechanical Engineering 2018年第1期13卷 107-119页

作者： Peng ZHAO Haibing GU Haoyang Mi Chengchen RAO Jianzhong FU lih-sheng TURNG State Key Laboratory of Fluid Power arid Mechatronic Systems Zhejiang University Hangzhou 310027 China Key Laboratory of 3DPrinting Process and Equipment of Zhejiang Province ZhejiangUniversity Hangzhou 310027 China Wisconsin institute for Discovery University of Wisconsin-MadisonMadison WI 53715 USA

Tissue engineering （TE） is an integrated discipline that involves engineering and natural science in the development of biological materials to replace, repair, and improve the function of diseased or missing tissues. Traditional medical and surgical treatments have been reported to have side effects on patients caused by organ necrosis and tissue loss. However, engineered tissues and organs provide a new way to cure specific diseases. Scaffold fabrication is an important step in the TE process. This paper summarizes and reviews the widely used scaffold fabrication methods, including conventional methods, electrospinning, three-dimensional printing, and a combination of molding techniques. Furthermore, the differences among the properties of tissues, such as pore size and distribution, porosity, structure, and mechanical properties, are elucidated and critically reviewed. Some studies that combine two or more methods are also reviewed. Finally, this paper provides some guidance and suggestions for the future of scaffold fabrication.

关键词： tissue engineering scaffolds electrospinning,3D printing molding techniques conventional methods

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Single-period Multi-Phase-Shifted Fiber Bragg Grating as Dispersion Compensator

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光学学报 2003年第S1期23卷 215-216页

作者： lih-Gen Sheu Kai-Ping Chuang Yinchieh Lai Department of Electronic Engineering Van Nung Institute of Technology 1 Van Nung Road Chung-Li Tao-Yuan 320 TaiwanInstitute of Electro-Optical Engineering Chiao-Tung University 1001 Ta Hsueh Road Hsinchu 300 TaiwanInstitute of Electro-Optical Engineering Chiao-Tung University 1001 Ta Hsueh Road Hsinchu 300 Taiwan

We theoretically demonstrate that a properly designed single-period multi-phase-shifted fiber Bragg grating can be used as a dispersion compensator. An overlap-step-scan exposure method for this new device is investig... 详细信息

关键词： FBG MPS of Single-period Multi-Phase-Shifted Fiber Bragg Grating as Dispersion Compensator that SC have

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Topological superconducting phase in high-T_(c) superconductor MgB_(2) with Dirac-nodal-line fermions

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npj Computational Materials 2019年第1期5卷 663-669页

作者： Kyung-Hwan Jin Huaqing Huang Jia-Wei Mei Zheng Liu lih-King Lim Feng Liu Department of Materials Science and Engineering University of UtahSalt Lake CityUT 84112USA institute for Quantum Science and Engineering and Department of PhysicsSouthern University of Science and Technology518055 ShenzhenChina institute for Advanced Study Tsinghua University100084 BeijingChina Collaborative innovation Center of Quantum Matter 100084 BeijingChina

Topological superconductors are an intriguing and elusive quantum phase,characterized by topologically protected gapless surface/edge states residing in a bulk superconducting gap,which hosts Majorana ***,all currently known topological superconductors have a very low transition temperature,limiting experimental measurements of Majorana *** we discover the existence of a topological Dirac–nodal-line state in a well-known conventional high-temperature superconductor,MgB_(2).First-principles calculations show that the Dirac–nodal-line structure exhibits a unique one-dimensional dispersive Dirac–nodal line,protected by both spatial-inversion and time-reversal symmetry,which connects the electron and hole Dirac *** importantly,we show that the topological superconducting phase can be realized with a conventional s-wave superconducting gap,evidenced by the topological edge mode of the MgB_(2) thin films showing chiral edge *** discovery may enable the experimental measurement of Majorana fermions at high temperature.

关键词： temperature. topological Dirac

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