检索结果-南通市图书馆

Effect of the repeated melting of mother ingot on the stability of icosahedral phase precipitated from Zr-Al-Ni-Cu-Ag glass

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2003年第6期46卷 639-644页

作者：闫志杰李金富王鸿华何顺荣周尧和 State Key lab of Metal Matrix Composites Shanghai Jiao Tong University Shanghai 200030 China Taiyuan Heavy Machinery Institute Taiyuan 030024 China

Differential scanning calorimetry (DSC) shows that repeated melting of mother ingot improves the stability of icosahedral phase (I-phase) precipitated from Zr65Al7.5Ni10Cu12.5Ag5 glass. The Kissinger analysis of crystallization implies that the effective activation energies for the precipitation of I-phase and its decomposition considerably increases due to the repeated melting of mother ingot. Repeated melting of mother ingot refines ingot microstructure. Because of structure heredity, the size of the short-range orders (SROs) in the glassy alloy produced from the mother ingot with finer microstructure becomes smaller, which makes the rearrangement of atoms more clifficult, and the I-phase more stable.

关键词： metallic glass, icosahedral phase, decomposition, short-range order.

Effect of gate length on the parameter degradation relations of PMOSFET under NBTI stress

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第11期23卷 496-501页

作者：曹艳荣何文龙曹成杨毅郑雪峰马晓华郝跃 School of Mechano-electric Engineering Xidian University Key lab of Wide Band-Gap Semiconductor Materials and Devices School of Microelectronics Xidian University School of Technical Physics Xidian University

The influence of PMOSFET gate length on the parameter degradation relations under negative bias temperature insta- bility （NBTI） stress is studied. The threshold voltage degradation increases with reducing the gate length. By calculating the relations between the threshold voltage and the linear/saturation drain current, we obtain their correlation coefficients. Comparing the test result with the calculated linear/saturation current value, we obtain the ratio factors. The ratio factors decrease differently when the gate length diminishes. When the gate length reduces to some degree, the linear ratio factor decreases from greater than 1 to nearly 1, but the saturation factor decreases from greater than l to smaller than 1. This results from the influence of mobility and the velocity saturation effect. Moreover, due to the un-uniform distribution of potential damages along the channel, the descending slopes of the curve are different.

关键词： negative bias temperature instability (NBTI) gate length degradation

Study on thermal infrared remote sensing of Yarlung Zangbo River and Bangong Co-Nujiang River suture belt in Qinghai-Tibet Plateau

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2006年第z2期49卷 108-113页

作者： BI Siwen, YAN Hao & WANG Changyao State Key laboratory of Remote Sensing Sciences, Institute of Remote Sensing Application, Chinese Academy of Sciences, Beijing 100101, China Key laboratory of Three-Dimensional Information Acquisition and Application, Ministry of Education, Capital Normal University, Beijing 100037, China Chinese Acad Sci Inst Remote Sensing Applicat State Key Lab Remote Sensing Sci Beijing 100101 Peoples R China Capital Normal Univ Minist Educ Key Lab Dimens Informat Acquisit & Applicat Beijing 100037 Peoples R China

The area change of heat abnormity is not in accordance with conclusions of former thermal infrared remote sensing studies of the Qinghai-Tibet Plateau, which were that the temperature of Yarlung Zangbo River suture belt of the southern Plateau is high and the northern temperature is low. The study result in this paper shows that the highest temperature is found in the Bangong Co-Nujiang River suture belt, the Yarlung Zangbo River suture belt temperature is the second highest, and the northern Tibet temperature is the lowest. The study demonstration area was the suture belt areas of the Yarlung Zangbo River and the Bangong Co-Nujiang River in the Qinghai-Tibet Plateau, where the land temperature of the Qinghai-Tibet Plateau and the bore temperature of field land surface were measured and the emissivity of land surface was calculated. In addition, the authors explore the mechanism of the relationship between thermal infrared remote sensing and constructing thermodynamics and reach four new conclusions about the thermodynamics of the Tibet Plateau.

关键词： Qinghai-Tibet Plateau, Yarlung Zangbo River-Bangong Co-Nujiang River, suture belt, thermal infrared remote sensing, heat abnormity.

NR-PSS (Nonlinear Robust Power System Stabilizer) for large synchronous generators and its large disturbance experiments on real time digital simulator

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2008年第4期51卷 337-352页

作者： LU Qiang ZHENG ShaoMing MEI ShengWei WANG Gang HUANG QiLi State Key lab of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Northeast China Grid Company Shenyang 110006China

On the foundation of nonlinear robust control and exact generator model, this paper presents a design principle of NR-PSS (Nonlinear Robust Power System Stabilizer) for multi-machine power system, based on which an industrial NR-PSS equipment is developed. For popularizing it, the proposed parameter setting method of NR-PSS is completely the same as the widely used parameter adjustment rule of PSS. By virtue of real time digital simulator (RTDS), large disturbance experiments are carried out to compare the performances between generator excitation system equipped with NR-PSS and PSS in order to verify the correctness of design theory. The results show that compared with classical PSS, the proposed NR-PSS can dramatically improve the generator damping and attenuate the oscillation much faster, enhance the generator damping and raise both the small signal and large disturbance transient stability transmission power limit remarkably. The NR-PSS equipment with independent intellectual property right has been successfully put into operation on a 300 MW generator in Baishan Hydro Plant of Northeast China Grid more than 10 months.

关键词： nonlinear robust control power system stabilizer real time digital simulation system large disturbance experiments

An efficient 3D ordered mesoporous Cu sphere array electrocatalyst for carbon dioxide electrochemical reduction

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第20期52卷 95-106页

作者： Jun-Tao Luo Guo-Long Zang Chuang Hu Tianjin Key lab of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityNo.92 Weijin RoadNankai DistrictTianjin 300072China

The electrochemical reduction of CO2 is a promising solution for sustainable energy research and carbon ***,this solution has been challenged by the lack of active and selective ***,we report a two-step synthesis of 3D ordered mesoporous Cu sphere arrays,which is fabricated by a dual template method using a poly methyl methacrylate(PMMA) inverse opal and the nonionic surfactant Brij 58 to template the mesostructure within the regular voids of a colloidal *** re,the well-ordered 3D interconnected bi-continuous mesopore s structure has advantages of abundant exposed catalytically active sites,efficient mass transport,and high electrical conductivity,which result in excellent electrocatalytic CO2 RR perfo *** prepared 3D ordered mesoporous Cu sphere array(3 D-OMCuSA) exhibits a low onset potential of-0.4 V at a 1 mA cm^-2 electrode current density,a low Tafel slope of 109.6 mV per decade and a long-term durability in 0.1 M potassium *** distinct features of 3 D-OMCuSA render it a promising method for the further develo p ment of advanced electrocatalytic materials for CO2 reduction.

关键词： 3D ordered mesoporous Cu sphere array electrocatalyst Copper nanoparticles Dual-template method CO2 electrochemical reduction reaction

Analysis with binaural auditory model and experiment on the timbre of Ambisonics recording and reproduction

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Acoustics 2015年第4期34卷 337-356页

作者： LIU Yang XIE Bosun Acoustic lab. Physics Dept.South China University of Technology

A scheme for analyzing the timbre in spatial sound with binaural auditory model is proposed and the Ambisonics is taken as an example for analysis. Ambisonics is a spatial sound system based on physical sound field reconstruction. The errors and timbre colorations in the final reconstructed sound field depend on the spatial aliasing errors on both the recording and reproducing stages of Ambisonics. The binaural loudness level spectra in Ambisonics recon- struction is calculated by using Moore＇s revised loudness model and then compared with the result of real sound source, so as to evaluate the timbre coloration in Ambisonics quantitatively. The results indicate that, in the case of ideal ＇independent signals, the high-frequency limit and radius of region without perceived timbre coloration increase with the order of Ambisonics. On the other hand, in the case of recording by microphone array, once the high-frequency limit of microphone array exceeds that of sound field reconstruction, array recording influences little on the binaural loudness level spectra and thus timbre in final reconstruction up to the high- frequency limit of reproduction. Based on the binaural auditory model analysis, a scheme for optimizing design of Ambisonics recording and reproduction is also suggested. The subjective experiment yields consistent results with those of binaural model, thus verifies the effectiveness of the model analysis.

关键词： Analysis with binaural auditory model and experiment on the timbre of Ambisonics recording and reproduction

A NOTE ON CONSTRUCTION OF HIGHER-ORDERSYMPLECTIC SCHEMES FROM LOWER-ORDER ONE VIAFORMAL ENERGIES

在线全文

学校读者我要写书评

暂无评论

Journal of Computational mathematics 1999年第6期17卷 561-568页

作者： Yi-fa Tang(State Key laboratory of Scientific and Engineering Computing, Institute of Computationalmathematics and Scientific/Engineering Computing, Academy of mathematics and SystemsSciences, Academia Sinica, P.O. Box 2719, Beijing 100080, P.R. China) Acad Sinica State Key Lab Sci & Engn Comp Inst Computat Math & Sci Engn Comp Acad Math & Syst Sci Beijing 100080 Peoples R China

In this paper, we will prove by the help of formal energies only that one can improve the order of any symplectic scheme by modifying the Hamiltonian symbol H, and show through examples that this action exactly and directly simplifies Feng's way of construction of higher-order symplectic schemes by using higher-order terms of generating functions.

关键词： Hamiltonian system symplectic scheme revertible scheme generating function formal energy

Effect of heat treatment on cyclic deformation properties of Fe-26Mn-10AI-C steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2019年第2期26卷 200-210页

作者： He Li Jian-ping Zhao Zhan-yu Wang Li Ding School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816JiangsuChina Jiangsu Key lab of Design and Manufacture of Extreme Pressure Equipnient Nanjing 211816JiangsuChina

Fully reversed tensile-compression low-cycle fatigue tests were performed at room temperature under strain amplitude of 0.4%.The monotonic tensile results show that Fe-26Mn-10A1-C steels are fully austenite and(he optimal combination of ultimate tensile strength and total elongation was present at 950°C with 65 GPa%.The fatigue results show that the specimen at 1050°C has the maximum fatigue life of 162,000 cycles,which is much longer than twinning-induced plasticity(TWIP)steels of the same strain *** hot-forging specimen shows high similarity with TWIP steels with rapid initial cyclic hardening followed by cyclic softening and cyclic *** solution heat treatment,it is noteworthy that,after rapid initial cyclic softening,another rapid cyclic hardening and a following decrease with fluctuation were observed at 1000°*** is reas on able to believe that it is caused by K-carbides precipitated during cyclic *** interesting phenomenon is cyclic stress subsidence observed at 1050°C during its saturation stage at the last quarter of the fatigue life,and the span is about 12.5%of whole fatigue life.

关键词： Fe-Mn-AI-C steel Low-cycle fatigue Cyclic hardening Cyclic softening Cyclic stress subsidence

General approach for atomically dispersed precious metal catalysts toward hydrogen reaction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Carbon Energy 2023年第7期5卷 100-111页

作者： Ruisong Li Daoxiong Wu Peng Rao Peilin Deng Jing Li Junming Luo Wei Huang Qi Chen Zhenye Kang Yijun Shen Xinlong Tian State Key laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine ChemistrySchool of Chemical Engineering and TechnologyHainan UniversityHaikouChina

As a carbon-free energy carrier,hydrogen has become the pivot for future clean energy,while efficient hydrogen production and combustion still require precious metal-based ***-atom catalysts(SACs)with high atomic utilization open up a desirable perspective for the scale applications of precious metals,but the general and facile preparation of various precious metal-based SACs remains ***,a general movable printing method has been developed to synthesize various precious metal-based SACs,such as Pd,Pt,Rh,Ir,and Ru,and the features of highly dispersed single atoms with nitrogen coordination have been identified by comprehensive *** importantly,the synthesized Pt-and Ru-based SACs exhibit much higher activities than their corresponding nanoparticle counterparts for hydrogen oxidation reaction and hydrogen evolution reaction(HER).In addition,the Pd-based SAC delivers an excellent activity for photocatalytic hydrogen *** for the superior mass activity of Ru-based SACs toward HER,density functional theory calculations confirmed that the adsorption of the hydrogen atom has a significant effect on the spin state and electronic structure of the catalysts.

关键词： hydrogen evolution reaction hydrogen oxidation reaction photocatalytic hydrogen evolution reaction precious metals single-atom catalysts