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Science China Mathematics 2019年第5期62卷 891-900页

作者： Chao zhang Department of Mathematics Guizhou University

Bongartz(2013) and Ringel(2011) proved that there is no gaps in the sequence of lengths of indecomposable modules for the ?nite-dimensional algebras over algebraically closed ?elds. The present paper mainly studies this "no gaps" theorem as to cohomological length for the bounded derived category Db(A) of a gentle algebra A: if there is an indecomposable object in D^b(A) of cohomological length l > 1, then there exists an indecomposable with cohomological length l-1.

关键词： cohomological length generalized string(band) derived discrete algebras

Energy performance analysis of multi-chiller cooling systems for data centers concerning progressive loading throughout the lifecycle under typical climates

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Building Simulation 2024年第10期17卷 1693-1708页

作者： yingbo zhang Hangxin Li Shengwei Wang Department of Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityHong KongChina Research Institute for Smart Energy The Hong Kong Polytechnic UniversityHong KongChina

The increasing demand for cooling energy in data centers has become a global *** studies lack a comprehensive analysis of the energy performance of widely used multi-chiller cooling systems in air-cooled data centers throughout their lifecycle,especially concerning progressive *** bridge this gap,this study conducts a thorough assessment of the energy performance of multi-chiller cooling systems throughout the entire ***,the impact of climate conditions on the energy efficiency of the cooling systems is analyzed,considering design variations for typical ***-chiller cooling system models are developed using the test data of cooling equipment and typical control *** energy performance of the cooling system is thoroughly analyzed under full-range cooling loads and climate *** show that free cooling time could differ up to 1442 hours at different part load ratios in the same ***,the cooling system’s coefficient of performance(COP)varies significantly,by up to 6,at different part load ratios,corresponding to a difference in power usage effectiveness(PUE)up to ***,the average cooling system COP throughout the lifecycle loading is found to be only 11.7,2.9 lower than the design system COP.

关键词： data center cooling system energy performance life-cycle operation power usage effectiveness(PUE) coefficient of performance(COP)

On tame and wild bocses

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Science China Mathematics 2005年第4期48卷 456-468页

作者： zhang yingbo XU Yunge Department of Mathematics Beijing Normal UniversityBeijing100875China Department of Mathematics Beijing Normal UniversityBeijing100875China Faculty of Mathematics & Computer Sciences Hubei University Wuhan430062China

We first give an alternative proof of the well-known Drozd's wild Theorem,which lowers down the dimension 43 to 20. Then we list more minimally wild bocses and discuss the possible differentials of the first arrow of ... 详细信息

关键词： Bocs, tameness, wildness, differential.

Optimum Calculation of Coal Pillars in Inclined Weathered Oxidation Zone

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Energy Engineering 2021年第3期118卷 707-714页

作者： yingbo zhang Shi Chen College of Water Resources and Architectural Engineering Northwest A&F UniversityYangling712100China Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas Ministry of EducationNorthwest A&F UniversityYangling712100China

In the mining process of coal mine,waterproof coal pillars should be set between the weathered oxidation zone and the first mining *** order to determine the reasonable upper limit of the first mining face of Hongyi Coal Mine,the waterproof coal pillar needs to be wide enough to resist the lateral hydrostatic pressure of the oxidation zone,and to ensure that the top plate aquifer does not run through the water guide crack zone,while also liberating as much stagnant coal as *** this paper,the first coal mine face’s waterproof coal pillar was calculated using conventional and optimized calculation methods,taking into account the dip angle of the coal seam,the height of the water-guide crack zone,and the rock shift influence zone,and finally the upper limit of the first face of Hongyi Coal Mine was determined.

关键词： efflorescent oxygenized belts upper limit water flowing fractured zone waterproof pillar

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Unified tame theorem

Science China Mathematics 2009年第9期52卷 2036-2068页

作者： zhang yingbo XU YunGe School of Mathematical Sciences Beijing Normal UniversityBeijing 100875China School of Mathematics and Computer Science Hubei UniversityWuhan 430062China

The well-known tame theorem tells that for a given tame bocs and a positive integer n there exist finitely many minimal bocses, such that any representation of the original bocs of dimension at most n is isomorphic to the image of a representation of some minimal bocses under a certain reduction functor. In the present paper we will give an alternative statement of the tame theorem in terms of matrix problem, by constructing a unified minimal matrix problem whose indecomposable matrices cover all the canonical forms of the indecomposable representations of dimension at most n for each non-negative integer n.

关键词： matrix problem canonical form representation tame type indecomposable 15A21 16G20 16G60 16G70

高塑性纳米准晶Mg-1.92Zn-0.34Y合金的热变形行为

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稀有金属材料与工程 2025年第1期54卷 184-190页

作者：曾崎王少阳荣鹏朱凯张英波高川云胡云峰成都飞机工业(集团)有限责任公司四川成都610092 西南交通大学材料科学与工程学院四川成都610031

纳米准晶增强Mg-Zn-Y合金室温具有超高延伸率,具有较广阔的应用前景,需进一步研究其热变形行为,为后续加工提供理论和应用基础。本工作采用半固态+热挤压的复合工艺制备了含有纳米准晶颗粒的Mg-1.92Zn-0.34Y(质量分数,下同)合金,探究本... 详细信息

纳米准晶增强Mg-Zn-Y合金室温具有超高延伸率,具有较广阔的应用前景,需进一步研究其热变形行为,为后续加工提供理论和应用基础。本工作采用半固态+热挤压的复合工艺制备了含有纳米准晶颗粒的Mg-1.92Zn-0.34Y(质量分数,下同)合金,探究本合金在250、300和350℃温度和10^(-3)、10^(-2)和10^(-1)s^(-1)应变速率条件下的高温变形机制,着重研究微量纳米准晶颗粒对Mg-1.92Zn-0.34Y合金热变形行为的影响。结果表明:半固态+热挤压的复合工艺制备了高塑性纳米准晶Mg-1.92Zn-0.34Y合金,其室温下抗拉延伸率为44%±2.6%,抗拉强度为258±2.0 MPa,屈服强度为176±1.6 MPa。通过本构关系获得平均变形激活能达到271.7812 k J/mol,其应力指数为6.7838;Mg-1.92Zn-0.34Y合金具有较好的热塑性,在研究条件下无失稳现象,表明纳米准晶颗粒能够强化其变形能力;最佳热加工区域是:330~350℃,10^(-3)~10^(-2)s^(-1),即高温低应变速率区。

关键词： Mg-Zn-Y合金纳米准晶高温压缩本构方程高塑性

Representation type of local and two-vertex bocses

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Science China Mathematics 2009年第5期52卷 949-958页

作者： zhang XueYing zhang yingbo ZHAO ShuangMei School of Mathematical Sciences Beijing Normal UniversityBeijing 100875China

Let k be an algebraically closed field. It has been proved by zhang and Xu that if a bocs is of tame representation type, then the degree of the differential of the first solid arrow must be less than or equal to 3. We will prove in the present paper that: The bocs is still wild when the degree of the differential of the first arrow is equal to 3. Especially, the bocs with only one solid arrow is of tame type if and only if the degree of the differential of the arrow is less than or equal to 2. Moreover, we classify in this case the growth problems of the representation category of the bocs and layout the sufficient and necessary conditions when the bocs is of finite representation type, tame domestic and tame exponential growth respectively.

关键词： bocs reduction tame representation type wild representation type domestic 15A21 16G20 16G60 16G70

High-ductility fine-grained Mg-1.92Zn-0.34Y alloy fabricated by semisolid and then hot extrusion

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Journal of Magnesium and Alloys 2023年第2期11卷 533-542页

作者： Qi Zeng yingbo zhang Kangning Li Ye Zhuang Jiaheng Li Yong JYuan Dongdi Yin School of Materials Science and Engineering Southwest Jiaotong UniversityNo.111North 1st Section of SecChengduSichuan 610031China Weichai Power Co. Fushou East StreetHigh-Tech Development ZoneWeifang 261061China

The combination of semisolid and hot extrusion processing was applied to refine the icosahedral quasicrystalline phase(I-phase) in an extruded Mg-1.92Zn-0.34Y(wt.%) alloy for the first time. The semisolid isothermal heat treatment transformed the micron-sized I-phase particles into nano lamellar eutectic(α-Mg + I-phase) with a lamellar spacing of ?86 nm. After subsequent hot extrusion at 250 ℃, the nano lamellar eutectic phases were broken into uniformly dispersed nanoscale I-phase particles. What’s more, the matrix microstructure was significantly refined with an equiaxed average grain size of 2.59 ± 0.81 μm, and an unusual texture component(most of the grains’ c-axis is parallel to the extrusion direction) was observed. The processed alloy exhibited a high tensile elongation to failure(EL) of 44 ± 2.6%with an ultimate tensile strength(UTS) of 258 ± 2.0 MPa and a tensile yield strength(TYS) of 176 ± 1.6 MPa at room *** high ductility from the combined effects of the grain refinement, dispersion of nanoscale I-phase particles, and the unusual *** uniform dispersion of nanoscale I-phase particles could promote grain refinement by particle stimulated nucleation mechanism, and thus bring the unusual texture(where the c-axis is aligned parallel to the extrusion direction during dynamic recrystallization, which contributed to ductility).

关键词： High ductility Unusual texture Nanoscale I-phase particle Microstructure

External field assisted hydrogen evolution reaction

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Nano Research 2023年第7期16卷 8638-8654页

作者： Jingwen Li Weinan Yin Junan Pan yingbo zhang Fengshun Wang Longlu Wang Qiang Zhao College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology) Nanjing University of Posts&Telecommunications(NJUPT)Nanjing 210023China

As a clean,efficient,and sustainable energy,hydrogen is expected to replace traditional fossil energy.A series of studies focusing on morphology regulation,surface modification,and structural reconstruction have been devoted to improving the intrinsic catalytic activity of non-noble metal ***,complex system structure design and the mutual interference of various chemical components would hinder the further improvement of hydrogen evolution *** recent years,external field assisted hydrogen evolution reaction(HER)has become a new research ***,we systematically summarize the promoting effects of various external fields on catalytic hydrogen production from the aspects of system design and catalytic mechanism,including electric field,thermal field,optical field,magnetic field,and acoustic ***,we discuss the key challenges facing this external field regulation strategy and put forward the prospect of future research *** sincerely expect that this review could not only provide a new insight into the basic mechanism of external-assisted catalysis,but also promote further research on improving HER performance from a more diverse and comprehensive perspective.

关键词： hydrogen evolution electric field thermal field optical field magnetic field acoustic field

A novel porous channel to optimize the cooling performance of PV modules

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Energy and Built Environment 2022年第2期3卷 210-225页

作者： yingbo zhang Chao Shen Chunxiao zhang Jihong Pu Qianru Yang Cheng Sun School of Architecture Harbin Institute of TechnologyKey Laboratory of Cold Region Urban and Rural Human Settlement Environment Science and TechnologyMinistry of Industry and Information TechnologyHarbin 150090China

This paper dealt with a series of numerical investigations on a new porous cooling channel applied to PV/T systems in order to improve the insufficient heat transfer in the conventional *** proposed porous cooling channel based on field synergy theory had a higher overall heat transfer coefficient,which enhanced the total efficiency of the PV/T *** numerical model was validated with experimental *** results showed that holes distributed non-uniformly near the outlet of the cooling water led to a better cooling effect,and a hole diameter of 0.005 m led to an optimal *** total efficiency of the PV module with the new cooling channel was 4.17%higher than the conventional one at a solar irradiance of 1000 W/m^(2)and an inlet mass flow rate of 0.006 kg/*** addition,as the solar irradiance increased from 300 to 1200 W/m^(2),the total efficiency of the new PV/T system dropped by 5.07%,which included reductions in both the electrical and thermal *** total efficiency was improved by 18.04%as the inlet mass flow rate of cooling water increased from 0.002 to 0.02 kg/s.

关键词： PV modules Heat regulation Field synergy theory PV cell temperature