检索结果-南通市图书馆

Mechanism of plant-soil feedback in a degraded alpine grassland on the Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2024年第2期17卷 188-199页

作者： Tiancai Zhou jian sun Peili {2. Key Laboratory of Ecosystem Network Observation and Modelling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China State Key Laboratory of Tibetan Plateau Earth System Resources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Key Laboratory of Biodiversity and environment on the Qinghai-Tibet Plateau Ministry of EducationLhasa 850011China Tibet Research Academy of Eco-environmental Sciences Lhasa 850000China College of Resources and environment University of Chinese Academy of SciencesBeijing 100049China

Although biotic and abiotic factors have been confirmed to be critical factors that affect community dynamics,their interactive effects have yet to be fully considered in grassland ***,we tested how soil nutrients and microbes regulated plant-soil feedback(PSF)in a degraded alpine *** results indicated that soil total carbon(STC;from 17.66 to 12.55 g/kg)and total nitrogen(STN;from 3.16 to 2.74 g/kg)exhibited significant(P2.on monocots growth when the soil was sterilized,a high proportion of pathogens(36%)in ND non-sterilized soil resulted in a strong negative PSF on *** contrast,the higher phenotypic plasticity of dicots coupled with a higher abundance of mutualists and saprophytes(70%)strongly promoted their survival and growth in SD with infertile *** findings identified a novel mechanism that there was a functional group shift from monocots with higher vulnerability to soil pathogens in the ND fertile soil to dicots with higher dependence on nutritional mutualists in the degraded infertile *** emerging irreversible eco-evolutionary in PSF after degradation might cause a predicament for the restoration of degraded grassland.

关键词： plant-soil feedback plant function groups degradation alpine grassland Tibetan Plateau

Survey on performance of vertical slot and nature-like fishways at Angu hydropower station, Southwest china

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Water Science and Engineering 2024年第1期17卷 83-91页

作者： Jun-jian sun Jia-yue {2. Qi Zhang Xiao-tao {2. Jun-jun Tan Powerchina Huadong Engineering Corporation Limited Hangzhou 311122China Hubei International Science and Technology Cooperation Base of Fish Passage China Three Gorges UniversityYichang 443002China

To restore dam-blocked natural fish migratory passages,a growing number of artificial fishways have been built in water conservancy and hydropower projects in *** Angu hydropower station involved diverse important fish habitats in the lower reaches of the Daduhe River in Southwest ***,a vertical slot fishway(VSF)and a nature-like fishway(NLF)were built near the backwater area of the reservoir to connect the upstream and downstream *** and aquatic ecological surveys were conducted after the completion of the project to estimate the fish passing effect of the two *** results indicated that both fishways were in effective operation and could maintain the desired hydrodynamic conditions and be used by several local fish *** the survey,149 fish from 15 species and 111 fish from 17 species were captured by the traps in the VSF and NLF,respectively,while 12.3 fish from 2. species were found in the downstream *** species captured in the VSF were not found in the NLF,and vice versa,which implied the different preferences of ***,3789 signals including 2.99 upward ones and 1690 downward ones were monitored with an ultrasonic fish detector at the inlet of the *** findings revealed the characteristics of fish species observed in and near the fishways and provided valuable insights into the different fish passing capabilities of VSFandNLF.

关键词： Vertical slot fishway Nature-like fishway Aguatic ecological survey Fishwaymonitoring Statistical analysis

Direct numerical simulation of shock wave/boundary layer interaction controlled by steady microjet in a compression ramp

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第10期37卷 83-102页

作者： Ruoye XIAO Dong sun jian YU school of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China State Key Laboratory of Aerodynamics Mianyang 621000China

Shock wave/boundary layer interaction in a 2.°turning angle of the compression ramp at Mach number 2.9 controlled by steady microjet is investigated using direct numerical *** different jet spacings which are termed as sparse,moderate and dense are considered,and the induced vortex system and shock structures are compared.A moderate jet spacing configuration is found to generate counter-rotating vortex pairs that transport high-momentum fluid towards the vicinity of wall and strengthen the boundary layer to resist separation,reducing the separation *** dense jet spacing configuration creates a larger momentum deficit region,reducing the friction downstream of the *** of pressure and pressure gradient reveals that dense jet spacing configuration reduces the intensity of separation *** impact of varying jet spacings on the turbulent kinetic energy transport mechanism is also investigated by decomposing the budget terms in the transport ***,the spectral characteristics of the separation region are studied using power spectral density and dynamic mode decomposition methods,revealing that moderate jet spacing configuration suppresses low-frequency fluctuations in the separation region.

关键词： Shock wave/boundary layer interaction Compression ramp Steady microjet Different jet spacings Direct numerical simulation

Heat Recuperation for the Self-Condensing CO_(2.Transcritical Power Cycle

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第5期33卷 1630-1641页

作者： PAN Lisheng shi Weixiu sun Yin sun Yiwei WEI Xiaolin State Key Laboratory of High-temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China school of environment and {2. Engineering Beijing University of Civil Engineering and ArchitectureBeijing 100044China

The supercritical CO_(2.Brayton cycle has potential to be used in electricity generation occasions with its advantages of high efficiency and compact *** on a so-called self-condensing CO_(2.transcritical power cycle,a model was established and four different layouts of heat recuperation process were analyzed,a without-recuperation cycle,a post-recuperation cycle,a pre-recuperation cycle and a re-recuperation *** results showed that the internal normal cycle's share of the whole cycle increases with increasing the cooling pressure and decreasing the final cooled *** load in the supercritical heater decreases with increasing the cooling *** perspective of performance,the re-recuperation cycle and the pre-recuperation cycle have similar thermal efficiency which is much higher than other two *** thermal efficiency and net power output have a maximum value with the cooling pressure,except in the condition with the final cooled temperature of 31℃.Considering both the complexity and the economy,the pre-recuperation cycle is more applicable than the other *** 35℃of the final cooled temperature,the thermal efficiency of the pre-recuperation cycle reaches the peak 0.34 with the cooling pressure of 8.4 MPa and the maximum net power output is 2.55.2. kW at 8.2.MPa of the cooling pressure.

关键词： CO_(2.transcritical power cycle heat recuperation process self-condensing

Substrate screening for superclean graphene growth using firstprinciples calculations

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第4期17卷 2216-2222页

作者： Zhihao Li Xiucai sun Xiaoli sun Wan-{2. Yin Zhongfan Liu College of energy Soochow Institute for Energy and Materials InnovationS(SIEMIS)and Jiangsu Provincial Key Laboratory for Advanced Carbon Materials and Wearable Energy TechnologiesSoochow UniversitySuzhou 215006China Graphene Basic Science Research Center Beijing Graphene Institute(BGI)Beijing 100095China Center for Nanochemistry Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular ScienceCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

Suppressing the formation of amorphous surface carbon and contaminants during the preparation of graphene by chemical vapor deposition remains an ongoing ***,we analyzed how substrate characteristics affect graphene quality by simulating margin extension,the nucleation process,and defect pegging configurations on mono-crystalline oriented metal substrates with the aim of enhancing graphene *** formation energy and nucleation potential,which are indirect substrate–graphene interaction features,were found to appropriately evaluate graphene *** crystallographic orientation of the metal substrate was discovered to be critical for producing superclean graphene.A low graphene defect density and high nucleation rate on the Cu(100)facet guarantee growth of high-quality graphene,especially in terms of suppressing the formation of amorphous *** addition,rapid kink growth and self-healing on the Cu(100)facet facilitate rapid graphene synthesis,which is also promoted by rapid kink splicing and margin self-repair on this *** study provides theoretical insight useful for the synthesis of superclean graphene.

关键词： superclean graphene defects nucleation metal substrates density functional theory calculations

Resilient performance of self-centering hybrid rocking walls with curved interface under pseudo-static loading

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第1期23卷 65-85页

作者： Su Xing Yan shi sun Xianglei Wang Tao school of Civil Engineering Shenyang Jianzhu UniversityShenyang 110168China Petrochina East china Design Institute Co. Ltd.Qingdao 266000China Qingdao Country Garden Bolin Real Estate Co. Ltd.Qingdao 266100China

Frame and rocking wall(FRW)structures have excellent resilient performance during ***,the concrete at interfacial corners of rocking walls(RWs)is easily crushed due to local extreme compression during the rocking *** innovative RW with a curved interface is proposed to prevent interfacial corners from producing local damage,enhancing its earthquake resilient performance(ERP).The precast wall panel with a curved interface is assembled into an integral self-centering hybrid rocking wall(SCRW)by two post-tensioned unbonded prestressed ***,two ordinary energy dissipation steel rebars and two shear reinforcements are arranged to increase the energy dissipation capacity and lateral *** SCRW specimens and one monolithic reinforced concrete(RC)shear wall(SW)were tested under pseudo-static loading to compare the ERPs of the proposed SCRW and the SW,focusing on studying the effect of the curved interface on the *** key resilient performance of rocking effects,failure modes,and hysteretic properties of the SCRW were *** results show that nonlinear deformations of the SCRW are concentrated along the interface between the SCRW and the foundation,avoiding damage within the *** restoring force provided by the prestressed tendons can effectively realize self-centering capacity with small residual deformation,and the resilient performance of the SCRW is better than that of monolithic *** addition,the curved interface of the SCRW makes the rocking center change and move inward,partially relieving the stress concentration and crush of *** rocking range of the rocking center is about 41.4%of the width of the SCRW.

关键词： self-centering hybrid rocking wall(SCRW) monolithic shear wall(SW) earthquake resilient performance(ERP) curved interface rocking center

Wave propagation and energy dissipation in viscoelastic granular media

在线全文

学校读者我要写书评

暂无评论

Journal of Central South university 2001年第3期13卷 185-188页

作者： sun Ye-zhi 1, WU Ai-xiang 1, LI jian-hua 1,2.(1. College of Resources, {2. and Civil Engineering, Central South Unive rsity, Changsha 410083, {2. 2. The 5th Building Company in Guangdong Province, Shaoguan 512.2., {2.) 1. College of Resources Environment and Civil Engineering Central South University 410083 Changsha China 2. The 5th Building Company in Guangdong Province 512026 Shaoguan China

In terms of viscoelasticity, the relevant theory of wave i n granular media is analyzed in this paper. Under the conditions of slight deforma tion of granules, wave equation, complex number expressions of propagation vecto r and attenuation vector, attenuation coefficient expressions of longitudinal wa ve and transverse wave, etc, are analyzed and deduced. The expressions of attenu ation coefficients of viscoelastic longitudinal wave and transverse wave show th a t the attenuation of wave is related to frequency. The higher the frequency is, the more the attenuation is, which is tested by the laboratory experiment. In a ddi tion, the energy dissipation is related to the higher frequency wave that is abs orbed by granular media. The friction amongst granular media also increase the e nergy dissipation. During the flowing situation the expression of transmission f actor of energy shows that the granular density difference is the key factor whi ch leads to the attenuation of vibrating energy. This has been proved by the exp eriment results.

关键词： viscoelastic granular media wave motion energy dissipation flowing situation

Influence of sintering time on microstructure and properties of hot oscillatory pressing sintered W–Cu refractory alloys

在线全文

学校读者我要写书评

暂无评论

Tungsten 2024年第2期6卷 323-332页

作者： Zi-Qian Wu Wei Zhao Ka Gao shi-Hao Du Qing-Quan Kong De-jian {2. Yang Gao school of Materials Science and Engineering Zhengzhou University of AeronauticsZhengzhou 450015China school of Mechanical Engineering University of Shanghai for Science and TechnologyShanghai 200093China Department of General Medicine Changhai HospitalShanghai 200000China Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering Wuhan University of Science and TechnologyWuhan 430081China Sichuan Province Engineering Technology Research Center of Powder Metallurgy Chengdu UniversityChengdu 610106China

W–Cu refractory alloys are widely used in aerospace,aviation,electronics,power,and other fi ***,because of its large melting point diff erence between alloy elements,the conventional powder metallurgy method required a long time of high temperature sintering is very likely to cause low density and abnormal grain size ***,90W-10Cu refractory alloys were successfully prepared by hot oscillatory pressing(HOP)under diff erent sintering time in this *** the infl uence of sintering time on the microstructure,grain size,density,Vickers hardness,room-tensile property,and electrical conductivity of the W–Cu refractory alloy was systematically *** results showed that during the short sintering time(30–90 min),the density,Vickers hardness,tensile strength,and electrical conductivity of the W–Cu refractory alloy increased signifi cantly to 98.7%,163.2. HV 30,507.3 MPa,and 14.2.International Annealed Copper Standard with the sintering time increasing,respectively,while its grain size showed no obvious *** the sintering time further increased to 12. min,the density was basically consistent with the sintering time of 90 ***,the prolonged high temperature sintering resulted in the grain growth of the samples,which caused the deterioration of the Vickers hardness,room-tensile strength,and conductivity properties of the W–Cu refractory *** the same sintering time,the density,Vickers hardness,and electrical conductivity of the HOP sintered W–Cu refractory alloy were signifi cantly higher than those of the HP sintered *** was indicated that high density,fi ne-grain,and excellent properties W–Cu refractory alloys could be prepared by hot oscillatory pressing under appropriate sintering time.

关键词： W–Cu refractory alloy Hot oscillatory pressing Sintering time Microstructure Property

Weavable thermoelectrics: advances, controversies, and future developments

在线全文

学校读者我要写书评

暂无评论

Materials Futures 2024年第1期3卷 63-94页

作者： Xiao-Lei shi Shuai sun Ting Wu {2. Tu Zhiming Zhou Qingfeng Liu Zhi-Gang Chen school of Chemistry and Physics ARC Research Hub in Zero-emission Power Generation for Carbon Neutralityand Centre for Materials ScienceQueensland University of TechnologyBrisbaneQueensland4000Australia State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211800People’s Republic of China school of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054People’s Republic of China

Owing to the capability of the conversion between thermal energy and electrical energy and their advantages of light weight,compactness,noise-free operation,and precision reliability,wearable thermoelectrics show great potential for diverse *** them,weavable thermoelectrics,a subclass with inherent flexibility,wearability,and operability,find utility in harnessing waste heat from irregular heat *** the rapid advancements in this field,a timely review is essential to consolidate the progress and ***,we provide an overview of the state of weavable thermoelectric materials and devices in wearable smart textiles,encompassing mechanisms,materials,fabrications,device structures,and applications from recent advancements,challenges,and *** review can serve as a valuable reference for researchers in the field of flexible wearable thermoelectric materials and devices and their applications.

关键词： thermoelectric weaving materials structure device