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Materials creation adds new dimensions to 3D printing

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Science Bulletin 2016年第22期61卷 1718-1722页

作者： Dongdong gu College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Institute of Additive Manufacturing (3D Printing) Nanjing University of Aeronautics and Astronautics

Additive manufacturing(AM),interchangeably termed as3D printing(3DP),has been defined as one of the key technologies in the national development strategies of a number of countries around the *** Makes,as the National Additive Manufacturing Innovation Institute,is the nation’s leading and collaborative partner in AM/3DP technology research,discovery,creation,and innovation,working efficiently to innovate and accelerate AM/3DP to increase America’s global manufacturing competitiveness(https://***).German

关键词： AM Materials creation adds new dimensions to 3D printing DMLS high SLA LMD

Feedback control for a class of second order hyperbolic distributed parameter systems

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Science China(Information Sciences) 2016年第9期59卷 156-164页

作者： Qin FU Weiguo gu Panpan gu Jianrong WU School of Mathematics and Physics Suzhou University of Science and Technology

This paper deals with the problem of state feedback control for a class of the distributed parameter systems with the disturbance term. And the considered distributed parameter systems are composed of the second order hyperbolic partial differential equations. Two different classes of restrictions on the disturbance term are given, one is that the disturbance term satisfies the linear growth constraint condition to the state variables of the system, and the other is that the disturbance term obeys the bound constraint under the significance of L2. Based on a variable structure method, the state feedback controllers are obtained by means of constructing appropriate Lyapunov functional. The closed-loop systems are globally asymptotically stable on W1,2（0, 1） × L2（0, 1） space under the effect of the state feedback control laws. Simulation results illustrate the effectiveness of the proposed method.

关键词： state feedback globally asymptotically stable second order hyperbolic distributed parameter sys tems variable structure method Lyapunov functional

Development and validation of abiotic ligand model for nickel toxicity to wheat(Triticum aestivum)

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Journal of Environmental Sciences 2017年第12期29卷 22-30页

作者： Yang Jiang Xueyuan gu Bojing Zhu Cheng gu State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China.

A terrestrial biotic ligand model（t-BLM） was developed to predict nickel toxicity to wheat（Triticum aestivum） root elongation in hydroponic solutions. The competitive effects of five major cations（Ca^（2＋）, Mg^（2＋）, Na~＋, K~＋and H~＋） on Ni toxicity were investigated and Mg^（2＋）was found to be a strong competitor, while H＋showed less competing effect. Besides free Ni^（2＋）,the toxicity induced by the species NiHCO_3~＋ was non-neglect able at pH 〉 7 because NiHCO_3~＋ occupied a significant fraction of total Ni under such condition. Thus, a t-BLM including Ni^（2＋）, NiHCO_3~＋, Mg^（2＋）, and H＋could successfully predict the nickel toxicity to wheat root elongation and it performed better prediction than the conventional free ion activity *** addition, the model was examined with two sets of independent experiments, which contained multiple cations and low-molecular-weight organic acids to mimic the rhizosphere condition. The developed t-BLM well predicted nickel toxicity in both experiments since it can account in both complexation and competition effects, suggesting its potential to be used in a complicated matrix like soil solution. This study provides direct evidence that the t-BLM is a reliable method for the risk assessment of nickel in terrestrial system.

关键词： Model Nickel Wheat Toxicity Risk assessment

Quasi-degenerate dark matter for DAMPE excess and 3.5 ke V line

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Science China(Physics,Mechanics & Astronomy) 2018年第10期61卷 30-35页

作者： Pei-Hong gu School of Physics and Astronomy Shanghai Jiao Tong University

We propose a quasi-degenerate dark matter scenario to simultaneously explain the 1.4 TeV peak in the high-energy cosmic-ray electron-positron spectrum reported by the DAMPE collaboration very recently and the 3.5 keV X-ray line observed in galaxies clusters and from the Galactic centre and confirmed by the Chandra and NuSTAR satellites. We consider a dark S U（2）′× U（1）′ gauge symmetry under which the dark matter is a Dirac fermion doublet composed of two S U（2）′ doublets with non-trivial U（1 ）′ charges. At the one-loop level the two dark fermion components can have a mass split as a result of the dark gauge symmetry breaking. Through the exchange of a mediator scalar doublet the two quasi-degenerate dark fermdons can mostly annihilate into the electron-positron pairs at the tree level for explaining the 1.4 TeV positron anomaly, meanwhile, the heavy dark fermion can very slowly decay into the light dark fermion with a photon at the one-loop level for explaining the 3.5 keV X-ray line. Our dark fermions can be also verified in the direct detection experiments.

关键词： dark matter DAMPE excess 3.5 ke V line

Breaking Through Bottlenecks for Thermally Conductive Polymer Composites:A Perspective for Intrinsic Thermal Conductivity,Interfacial Thermal Resistance and Theoretics

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Nano-Micro Letters 2021年第7期13卷 118-126页

作者： Junwei gu Kunpeng Ruan MOE Key Laboratory of Material Physics and Chemistry Under Extraordinary Conditions Shaanxi Key Laboratory of Macromolecular Science and TechnologySchool of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’anShaanxi 710072P.R.China

Rapid development of energy,electrical and electronic technologies has put forward higher requirements for the thermal conductivities of polymers and their ***,the thermal conductivity coefficient(λ)values of prepared thermally conductive polymer composites are still difficult to achieve expectations,which has become the bottleneck in the fields of thermally conductive polymer *** at that,based on the accumulation of the previous research works by related researchers and our research group,this paper proposes three possible directions for breaking through the bottlenecks:(1)preparing and synthesizing intrinsically thermally conductive polymers,(2)reducing the interfacial thermal resistance in thermally conductive polymer composites,and(3)establishing suitable thermal conduction models and studying inner thermal conduction mechanism to guide experimental ***,the future development trends of the three above-mentioned directions are foreseen,hoping to provide certain basis and guidance for the preparation,researches and development of thermally conductive polymers and their composites.

关键词： Thermally conductive polymer composites Intrinsic thermal conductivity Interfacial thermal resistance Thermal conduction models Thermal conduction mechanisms

A single image dehazing method based on decomposition strategy

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Journal of Systems Engineering and Electronics 2022年第2期33卷 279-293页

作者： QIN Chaoxuan gu Xiaohui School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China Southwest Technology and Engineering Research Institute Chongqing 400039China

Outdoor haze has adverse impact on outdoor image quality,including contrast loss and poor *** this paper,a novel dehazing algorithm based on the decomposition strategy is *** combines the advantages of the two-dimensional variational mode decomposition(2DVMD)algorithm and dark channel *** original hazy image is adaptively decom-posed into low-frequency and high-frequency images according to the image frequency band by using the 2DVMD *** low-frequency image is dehazed by using the improved dark channel prior,and then fused with the high-frequency ***,we optimize the atmospheric light and transmit-tance estimation method to obtain a defogging effect with richer details and stronger *** proposed algorithm is com-pared with the existing advanced *** results show that the proposed algorithm has better performance in comparison with the state-of-the-art algorithms.

关键词： single image dehazing decomposition strategy image processing global atmospheric light

An Improved Method of Ambiguity Resolution in GNSS Positioning

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Chinese Journal of Electronics 2019年第1期28卷 215-222页

作者： gu Xiaoying ZHU Bocheng School of Electronics Engineering and Computer Science Peking University

High precision navigation with positioning accuracy of decimeter or even centimeter is becoming more and more important in many fields. Accurate carrier phase observations are the prerequisites for this requirement. Because they have much lower measurement noises than the code observations which are primarily used nowadays. However, the existence of integer ambiguity when counting cycles of carrier phases prohibits the straightforward application of the measurements. Once the integer ambiguity has been resolved, the application of carrier phase measurement is almost equivalent to pseudorange however with much higher precision. Therefore ambiguity resolution is key for fast and high precision positioning. The success rate of ambiguity resolution is affected by the ionospheric delay and observation noise. In previous methods, ionospheric errors are simply ignored. To resolve ambiguity reliably and quickly, we propose a modified method for precise point *** analyze the characteristics of the dual-frequency combinations of original observations and the ones with longer wavelengths and lower noises are preferable. The wide-lane and sub-wide-lane combinations with higher success rates are chosen for ambiguity resolution. Extra pseudoranges are included to eliminate the ionospheric delay which hampers ambiguity resolution seriously. After the combined ambiguities have been resolved, the original ambiguities of each frequency can be calculated from the linearly independent equations. Based on real Global positioning system(GPS) navigation data, performances of the modified method are tested and compared with that of the traditional method. The results show that the modified method is less affected by ionospheric delay and can obtain more accurate ambiguity resolution.

关键词： Global navigation satellite system Integer ambiguity resolution Precise point positioning High precision positioning

Semi-clathrate hydrate based carbon dioxide capture and separation techniques

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Frontiers of Environmental Science & Engineering 2023年第12期17卷 1-29页

作者： Lijuan gu Hailong Lu Beijing International Center for Gas Hydrate School of Earth and Space SciencesPeking UniversityBeijing 100871China National Engineering Research Center for Gas Hydrate Exploration and Development Guangzhou 511466China

CO_(2)is considered as the main contributor to global warming,and hydrate enclathration is an efficient way for carbon capture and separation(CCS).Semi-clathrate hydrate(SCH)is a type of clathrate hydrate capable of encaging CO_(2)molecules under mild temperature and pressure *** has numerous unique advantages,including high thermal stability,selective absorption of gas molecules with proper size and recyclable,making it a promising candidate for *** SCH based CCS technology is in the developing stage and great efforts have to be conducted to improve the performance that is determined by their thermodynamical and structural *** review summarizes and compares the thermodynamic and structural properties of SCH and quaternary salt hydrates with gas mixtures to be captured and *** on the description of the physical properties of SCH and hydrate of quaternary salts with gas mixture,the CO_(2)capture and separation from fuel gas,flue gas and biogas with SCH are *** review focuses on the use of tetra-nbutyl ammonium halide and tetra-n-butyl phosphonium halide,which are the current application *** review aims to provide guidance for the future applications of SCH.

关键词： Semi-clathrate hydrate Tetra-n-butyl ammonium halide Tetra-n-butyl phosphonium halide Structure Thermodynamical properties CO_(2) capture and separation

A High-Order Fully Actuated System Approach for a Class of Nonlinear Systems

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Journal of Systems Science & Complexity 2022年第2期35卷 714-730页

作者： gu Dake WANG Shuo School of Automation Engineering Northeast Electric Power UniversityJilin 132012China

This paper utilizes the high-order fully actuated(HOFA)system approach to synthesize a class of nonlinear ***,the original nonlinear system can be rewritten in a quasi-linear form,which is more general than other nonlinear systems,such as strict-feedback *** on a rank condition,the quasi-linear system can be transformed into a canonical ***,a simple transformation is adopted to convert the above canonical form into the HOFA *** an HOFA model is derived,the authors design a controller to make the closed-loop system a constant linear system with the desired ***,a numerical example illustrates the fitness and effectiveness of the proposed approach.

关键词： Canonical form closed-loop eigenstructure full-actuation high-order systems quasilinear systems