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A new family of differentially 4-uniform permutations over F_(2^(2k))for odd k

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Science China Mathematics 2016年第6期59卷 1221-1234页

作者： PENG Jie TAN ChikHow wang.qichun School of Mathematics and Statistics Central China Normal UniversityWuhan 430079China Shanghai Key Laboratory of Intelligent Information Processing Shanghai 200433China Temasek Laboratories National University of SingaporeSingapore 117411Singapore

We study the differential uniformity of a class of permutations over F2 n with n even. These permutations are different from the inverse function as the values x^(-1) are modified to be(γx)^(-1) on some cosets of a fixed subgroup γ of F_(2n)~*. We obtain some sufficient conditions for this kind of permutations to be differentially 4-uniform, which enable us to construct a new family of differentially 4-uniform permutations that contains many new Carlet-Charpin-Zinoviev equivalent(CCZ-equivalent) classes as checked by Magma for small numbers n. Moreover, all of the newly constructed functions are proved to possess optimal algebraic degree and relatively high nonlinearity.

关键词： differential uniformity permutation algebraic degree nonlinearity coset

Recent advances on electrochemical methods in fabricating two-dimensional organic-ligand-containing frameworks

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SmartMat 2021年第3期2卷 299-325页

作者： Xiang wang Pengfei She qichun Zhang Department of Materials Science and Engineering City University of Hong KongHong KongChina Center of Super-Diamond and Advanced Films(COSDAF) City University of Hong KongHong KongChina

Organic-ligand-containing frameworks have drawn considerable attention due to their multifunctional properties as well as tunable structures for broad *** numerous synthesis methods developed in the past two decades,electrochemical processing has been demonstrated as one of the most efficient,safe,and facile ways to realize the large-scale and highly controllable production of organic-ligand-containing *** this review,the progress of electrochemically induced crystallization and thin film fabrication of organic-ligand-containing frameworks is summarized in a well-rounded ***,the mechanism and processing parameters are also ***,the main challenges are also expounded for providing some guidance on the future development of organic-ligand-containing frameworks,especially for covalent-organic frameworks and hydrogen-bonded organic frameworks.

关键词： covalent organic frameworks electrophoretic deposition electrosynthesis films hydrogen-bonded organic frameworks metal-organic frameworks

Shooting flexible electronics

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Frontiers of physics 2021年第1期16卷 39-41页

作者： qichun Zhang Department of Materials Science and Engineering City University of Hong KongHong KongChina

The trends of the future electronic devices should be miniaturized,flexible,stable,portable,light,and highly *** flexible electronic products(i.e.,flexible display products^([1-3]),batteries^([4,5]),cell phones[6])have been commercially available recently,which represents the starting of a new era in electronics,these progresses are still in their infancy and more efforts are required to boom their multifunction and speed up their marketization from *** their low-cost and mass-productive synthesis technologies,rich species,high performances,and especially,the excellent flexibility and stability,organic materials(insulating,conductive and semiconducting)have triggered the tide of the development of"plastic electronics",especially in transistors,an indispensable logic device in these logic-control based devices(i.e.,intelligent electronics).

关键词： electronics starting portable

Experimental Testing of Greenhouse-Integrated Vanadium-Titanium Black Ceramic Solar Absorbers

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Journal of Thermal Science 2022年第6期31卷 1891-1902页

作者： DING Ding LIU Chunlu wang.qichun ZHAO Zhibin XU Jianhua CAO Shuliang School of Architecture and Civil Engineering Xihua UniversityChengdu 610039China School of Architecture and Built Environment Deakin UniversityGeelongVictoria 3220Australia Advanced Materials Institute Qilu University of Technology(Shandong Academy of Sciences)Ji'nan 250014China Shandong Lide Innovative Energy Technology Co. LtdJi'nan 251400China Shandong Tianhong Arc Board Co. LtdJi'nan 250014China

As a solution for solar heating, the low-cost and long-life vanadium-titanium black ceramic solar absorbers have been used in rural construction. However, in contrast to its high absorptance(0.93-0.97), ceramic also has high emissivity(approximately 90%) and low thermal conductivity(1.3 W/(m·K)). Without a glaze covering, ceramic absorbers cannot meet the industrial standard. This paper assumes that glaze covering can be substituted by insulation film in a solar greenhouse. To verify this assumption, field experiments were conducted. First, a traditional greenhouse in the Tacheng Basin, a severely cold area in China, was renovated to improve its passive thermal performance. Then, 90 m^(2) of ceramic absorbers and floor coils as well as a water tank were installed inside the greenhouse, which made the entire construction act as an integrated solar collector. This heat collection and release system moderately increased the indoor air temperature(0.9℃-22.4℃) and substantially increased the soil temperature(15.5℃-31.2℃). The average daily useful heat gain under a daily solar insolation value of 17 MJ/m^(2) was 13.8 MJ, and the mean value of the collection efficiency was 0.81. Furthermore, the payback time of the project(7 years) is short, which is principally due to the low cost of ceramic materials and the financial savings of the shared construction components(e.g., transparent cover, metal frame and extra insulation). In conclusion, the main contribution of this study is the verification that it is feasible to replace glaze covering with insulation film in a novel greenhouse-integrated vanadium-titanium black ceramic solar system.

关键词： greenhouse design solar absorber transparent film vanadium extraction ceramic coating

STUDY ON HIGH ACID LEACHING REACTIVE CALCINED KAOLIN

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Journal of Wuhan University of Technology(Materials Science) 1999年第1期14卷 19-24页

作者： Zhang, qichun Yi, Qiaoming Chengdu Inst Technol Dept Mat Sci & Engn Chengdu 610059 Peoples R China

Leaching experiments on metakaolin show that the final Al extraction ratio reached in a batch reaction is strikingly influenced by the inferior pore structure geometry of the metakaolin pellets. By calcining kaolin particles adhered in low humidity state, a variety of metakaolin pellet, inside which a large openings structure developed, has been prepared. The structure remarkably benefits leachant ion transference, so, the variety has high acid leaching reactivity, even coarse as the pellets are, its aluminum extracted ratio still has a linear relationship with leaching time, and the leaching kinetics is maintained zero order up to a significant conversion degree. A revised Pellet-Particle Model has been developed to interpret the structure influence on Al extraction ratio. (Author abstract) 4 Refs.

关键词： large openings structure aluminum extraction reactivity

Construction of a cement-rebar nanoarchitecture for a solution-processed and flexible film of a Bi_(2)Te_(3)/CNT hybrid toward low thermal conductivity and high thermoelectric performance

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Carbon Energy 2022年第1期4卷 115-128页

作者： Zhijun Chen Haicai Lv qichun Zhang Hanfu wang Guangming Chen College of Materials Science and Engineering Shenzhen UniversityShenzhenChina College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhenChina Department of Materials Science and Engineering City University of Hong KongHong KongChina Center of Super-Diamond and Advanced Films(COSDAF) City University of Hong KongHong KongChina National Center for Nanoscience and Technology BeijingChina

Solution processability and flexibility still remain major challenges for many thermoelectric(TE)materials,including bismuth telluride(Bi_(2)Te_(3)),a typical and commercially available TE ***,we report a new solutionprocessed method to prepare a flexible film of a Bi_(2)Te_(3)/single-walled carbon nanotube(SWCNT)hybrid,where the dissolved Bi_(2)Te_(3) ion precursors are mixed with dispersed SWCNTs in solution and recrystallized on the SWCNT surfaces to form a“cement-rebar”-like *** hybrid film shows an n-type characteristic,with a stable Seebeck coefficient of^(−1)00.00±1.69μVK^(−1) in ***,an extremely low in-plane thermal conductivity of∼0.33Wm^(−1) K^(−1) is achieved at 300 K,and the figure of merit(ZT)reaches 0.47±*** addition,the TE performance is independent of mechanical *** unique“cement-rebar”-like architecture is believed to be responsible for the excellent TE performances and the high *** results provide a new avenue for the fabrication of solution-processable and flexible TE hybrid films and will speed up the applications of flexible electronics and energy conversion.

关键词： Bi_(2)Te_(3) carbon nanotube hybrid solution-processed thermoelectrics

Covalent organic framework containing dual redox centers as an efficient anode in Li-ion batteries

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SmartMat 2022年第4期3卷 685-694页

作者： Yifan Tong Zhaopeng Sun Jiawen wang Weiwei Huang qichun Zhang School of Environmental and Chemical Engineering Yanshan UniversityQinhuangdaoChina Department of Materials Science and Engineering City University of Hong KongKowloonHong KongChina Center of Super-Diamond and Advanced Films(COSDAF) City University of Hong KongKowloonHong KongChina

Covalent organic frameworks(COFs)with periodic channels and tunable chemical structures have been widely considered as promising electrode materials in rechargeable ***,the design and construction of high-performance COFs-based electrodes still face some challenges in the introduction of multiple efficient redox centers as well as the reduction of dead *** address these issues,a unique COF containing double active centers(C═N and N═N)is developed as an anode in rechargeable lithium-ion batteries(LIBs).The as-prepared COF displays excellent electrochemical performance due to its remarkable structural stability and the existence of many active ***,its electrochemical performance is significantly better than that of the small molecule compound or the linear polymer with the same construction *** at a high current density of 5 A/g,the LIBs with COF electrodes remain at a high discharge capacity of 227 mAh/g after 2000 ***,the distinction in electrochemical performances of these three materials is further revealed by *** study illustrates the importance of molecular structure design for improving the performance of organic electrodes.

关键词： anodes covalent organic frameworks dual active sites molecular structure design

Manipulating asymmetric photon transport through electrical control： a new strategy to construct optical diodes or isolators

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Science China Chemistry 2018年第11期61卷 1351-1352页

作者： Yinjuan Huang qichun Zhang School of Materials Science and Engineering Nanvang Technological University Singapore 639798 Singapore Division of Chemistry and Biological Chemistry School of Physical and Mathematical Sciences Nanyang Technological University Singapore 639798 Singapore

Nowadays, the main barrier which restricts the applications of integrated photonics for construction of optical diodes or isolators in photonic integrated circuits is the effective asymmetric photon transport. Accordingly, a series of photonic schemes have been developed to break this conundrum [1,2]. On the other hand, exciton polariton （EP） formed through the strong coupling between photons and exitons can propagate along the waveguide, which can therefore provide schemes to manipulate photons at microscale [3].

关键词：光二极管控制操作不对称光子运输构造集成电路波导

Spatiotemporal patterns of snow cover retrieved from NOAA-AVHRR LTDR: a case study in the Tibetan Plateau, China

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International Journal of Digital Earth 2017年第5期10卷 504-521页

作者： Siyuan wang Hang Yin qichun Yang Hui Yin Xiaoyue wang Yaoyao Peng Ming Shen Key Laboratory of Digital Earth Science Institute of Remote Sensing and Digital EarthChinese Academy of ScienceBeijingPeople’s Republic of China Pacific Northwest National Laboratory RichlandWAUSA

Snow cover plays an important role in hydrological processes and seasonal water *** in the Tibetan Plateau(TP),snow cover is an important source of the Yangtze River,Yellow River and Lancang River(SRYYL),which greatly influences regional water *** this study,we quantified the temporal trend and spatial variation of snow cover across the TP by calibrating and developing the Advance Very High Resolution Radiometer(AVHRR)Long Term Data Record(LTDR)-derived snow cover products during *** also examined the relationship of snow cover with temperature and precipitation over the TP during 1982–*** results indicate that seasonal snow cover generally starts to accumulate from central plateau in October,while significant melting starts to occur from the southeastern plateau in May of following *** long-term variability of snow cover is characterized by the tendency for a slight decrease in the mean snow coverage during the period of hydrological year(HY)1982–1993 and a slight increase from HY2001 to 2011,but the total snow cover area remains relatively stable over the past 30 *** results also show that temperature plays a critical role in controlling the snow cover days.

关键词： Snow cover temporal-spatial variation NOAA-AVHRR LTDR Tibetan Plateau