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Irreversibility and transformation randomness of thermoelastic martensitic transformation in Ni–Ti alloys

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Rare Metals 2015年第12期34卷 833-837页

作者： Tian-Wei Liu Yan-jun zheng Li-Shan Cui Department of Materials Science and Engineering China University of Petroleum

In this work, the in situ optical observation was carried out in complete and incomplete transformation cycles of Ni–Ti alloys. In complete transformation cycles, initial martensite plates nucleate randomly in austenite. However, in a partial transformation cycle, the existing martensite plates have an influence on guiding the formation of subsequent martensite plates. And the randomness decreases with the decrease in transformation volume involved in the partial cycle. It is suggested that the randomness of transformations contributes to the introduction of defects, and the irreversibility associates with transformation randomness of martensite plates. For instance, a higher randomness in transformations could introduce more defects and more obvious irreversibility. On the other hand, defects generated in thermoelastic martensitic transformation are responsible for the hysteresis of transformations. Therefore, the randomness of transformations also contributes to the transformation hysteresis. These results could help further understanding on some martensitic transformation phenomena of shape memory alloys, such as the nonlinear and history-dependent characteristic.

关键词： Thermoelastic martensitic transformation Shape memory alloys Transformation sequence Hysteresis

Interface Electric Field Confinement Effect of High-Sensitivity Lateral Ge/Si Avalanche Photodiodes

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Tsinghua Science and Technology 2019年第1期24卷 1-8页

作者： Wenzhou Wu Zhi Liu jun zheng Yuhua Zuo Buwen Cheng the State Key Laboratory on Integrated Optoelectronics Institute of Semiconductor Chinese Academy of Sciences the College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences

A novel lateral Ge/Si avalanche photodiode without a charge region is investigated herein using device physical simulation. High field is provided by the band-gap barrier and build-in field at the Ge/Si interface in the vertical direction. Modulating the Si mesa thickness(0-0.4 μm) and impurity concentration of the intrinsic Si substrate(1×10^(16)-4×10^(16)cm^(-3)) strengthens the electric field confinement in the substrate region and provides a high avalanche multiplication in the Si region. When the Si mesa thickness is 0.3 μm, and the impurity concentration of the Si substrate is 2×10^(16) cm^(-3), the Lateral Avalanche PhotoDiode(LAPD) exhibits a peak gain of 246 under 1.55 μm incident light power of -22.2 dBm, which increases with decreasing light intensity.

关键词： avalanche photodiodes lateral structure electric field confinement high gain

Fretting Wear Behavior of Medium Carbon Steel Modified by Low Temperature Gas Multi-component Thermo-chemical Treatment

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Chinese Journal of Mechanical Engineering 2010年第3期23卷 288-296页

作者： LUO jun zheng Jianfeng PENG Jinfang HE Liping ZHU Minhao Traction Power State Key Laboratory Southwest Jiaotong University Chengdu 610031 China

The introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component （such as carbon, nitrogen, sulphur and oxygen, etc） thermo-chemical treatment（LTGMTT） can overcome the brittleness of nitriding process, and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly. However, there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now, which limits the applications of fretting. So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50 （0.48%C） steel prepared by low temperature gas multi-component thermo-chemical treatment （LTGMTT） technology. The fretting wear tests of the modified layer flat specimens and its substrate （LZ50 steel） against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2 μm to 40 μm. Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope（SEM）, optical microscope（OM）, X-ray diffraction（XRD） and surface profilometer. The experimental results showed that the modified layer with a total thickness of 60 μm was consisted of three parts, i.e., loose layer, compound layer and diffusion layer. Compared with the substrate, the range of the mixed fretting regime（MFR） of the LTGMTT modified layer diminished, and the slip regime（SR） of the modified layer shifted to the direction of smaller displacement amplitude. The coefficient of friction（COF） of the modified layer was lower than that of the substrate in the initial stage. For the modified layer, the damage in partial slip regime（PSR） was very slight. The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination. The modified layer presented better wear res

关键词： fretting wear fretting regimes low temperature gas multi-component thermo-chemical treatment(LTGMTT) modified layer medium carbon steel

AIM Study on the Reaction of CH2SH Radical with Fluorine Atom

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Chinese Journal of Chemical Physics 2008年第2期21卷 123-130页

作者： Cui-hong Suna Yan-li Zeng Ling-peng Meng Shi-jun zheng Institute of Computational Quantum Chemistry Hebei Normal University Shijiazhuan& 050016 China Chemistry and Chemical Engineering College Shijiazhuang University Shijiazhuang 050035 China

The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G（d,p） and MP2（Full）/6-311G（d,p）. The computational results show that the reaction has three channels and proceeds by the addition of fluorine atoms on carbon or sulfur sites of CH2SH, forming initial intermediates. The calculated results show that the channel, in which fluorine attaches to the carbon atom to form CH2S and HF, is the most likely reaction pathway. Topological analysis of electron density was carried out for the three channels. The change trends of the chemical bonds on the reaction paths were discussed. The energy transition states and the structure transition regions （states） of the three channels were found. The calculated results show that the structure transition regions are broad in unobvious exothermic reactions or unobvious endothermic reactions, and are narrow in obvious exothermic reactions or obvious endothermic reactions.

关键词： Radical reaction Energy transition state Structure transition state Structure transition region Topological analysis of electronic density

A catastrophic natural disaster chain of typhoon-rainstorm-landslide-barrier lake-flooding in Zhejiang Province, China

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Journal of Mountain Science 2021年第8期18卷 2108-2119页

作者： CUI Yu-long HU jun-hong XU Chong zheng jun WEI Jiang-bo School of Civil Engineering and Architecture Anhui University of Science and TechnologyHuainan232001China National Institute of Natural Hazards Ministry of Emergency Management of China(former Institute of Crustal DynamicsChina Earthquake Administration)Beijing100085China Department of Civil Engineering Zhejiang UniversityHangzhou310058China College of Geology and Environment Xi’an University of Science and TechnologyXi’an710054China

On August 10,2019,due to the effect of a rainstorm caused by Super Typhoon Lekima,a landslide occurred in Shanzao Village,*** blocked the Shanzao stream,forming a barrier lake,and then the barrier lake *** is a rare natural disaster chain of typhoon-rainstorm-landslide-barrier *** study was built on field surveys,satellite image interpretation,the digital elevation model(DEM),engineering geological analysis and empirical *** purpose was to reveal the characteristics and causes of the landslide,the features and formation process of the barrier lake and the dam break flooding *** results show that the volume of the landslide deposit is approximately 2.4×105 *** burst mode of the landslide dam is overtopping,which took only 22 minutes from the formation of the landslide dam to its *** dam-break peak flow was 1353 m3/s,and the average velocity was 2.8–3.0 m/*** study shows that the strongly weathered rock and soil slope has low strength and high permeability under the condition of heavy rainfall,which reminds us the high risk of landslides and the importance of accurate early warning of landslides under heavy rainfalls in densely populated areas of Southeast China,as well as the severity of the disaster chain of typhoon-rainstorm-landslide-barrier lake-flooding.

关键词： Natural disaster chain Landslide Barrier lake Dam break flood Typhoon Lekima

Array based HV/VH tree: an effective data structure for layout representation

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第3期13卷 232-237页

作者： Jie REN Wei-wei PAN Yong-jun zheng zheng SHI Xiao-lang YAN Institute of VLSI Design Zhejiang UniversityHangzhou 310027China

We present a new data structure for the representation of an integrated circuit layout. It is a modified HV/VH tree using arrays as the primary container in bisector lists and leaf nodes. By grouping and sorting objects within these arrays together with a customized binary search algorithm, our new data structure provides excellent performance in both memory usage and region query speed. Experimental results show that in comparison with the original HV/VH tree, which has been regarded as the best layout data structure to date, the new data structure uses much less memory and can become 30% faster on region query.

关键词： Very large scale integration (VLSI) Layout representation HV/VH trees Region query

Viability decision of linear discrete-time stochastic systems with probability criterion

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控制理论与应用（英文版） 2009年第3期7卷 297-300页

作者： Wansheng TANG jun zheng Jianxiong ZHANG Institute of Systems Engineering Tianjin University Tianjin 300072 China

In this paper, the optimal viability decision problem of linear discrete-time stochastic systems with probability criterion is investigated. Under the condition of sequence-reachable discrete-time dynamic systems, the existence theorem of optimal viability strategy is given and the solving procedure of the optimal strategy is provided based on dynamic programming. A numerical example shows the effectiveness of the proposed methods.

关键词： Stochastic systems Decision-making Probability criterion Dynamic programming

Hall Effect in Quasicrystals

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Wuhan University Journal of Natural Sciences 2005年第2期10卷 385-388页

作者： ZHOUXiang HUCheng-zheng GONGPing WANGAi-jun SchoolofPhysicsandTechnology WuhanUniversityWuhan430072HubeiChina

The relations between Hall effect and symmetry are discussed for all 2- and3-dimensional quasicrystals with crystallographically forbidden symmetries. The results show thatthe numbers of independent components of the Hall coefficient (R_H ) are onefor 3-dimensionalquasicrystals, two for those 2-dimensional quasicrystals whose symmetry group is non-Abclian, andthree for those 2-dimensional quasicrystals whose symmetry group is Abelian, respectively. Thequasicrystals with the same number of independent components have the same form of the components ofR_H.

关键词： quasicrystal Hall effect symmetry

Landslides triggered by the 1970 Ms 7.7 Tonghai earthquake in Yunnan,China: an inventory, distribution characteristics, and tectonic significance

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Journal of Mountain Science 2022年第6期19卷 1633-1649页

作者： CUI Yu-long HU jun-hong XU Chong MIAO Hai-bo zheng jun School of Civil Engineering and Architecture Anhui University of Science and TechnologyHuainan 232001China National Institute of Natural Hazards Ministry of Emergency Management of ChinaBeijing 100085China Department of Civil Engineering Zhejiang UniversityHangzhou 310058China

The 1970 Tonghai earthquake, which occurred on January 5, 1970, in Tonghai County, Yunnan Province, China, triggered a large number of landslides. Since the occurrence of the earthquake, there have been a huge number of research reports on the seismogenic structure and earthquake mechanism, but rare reports on the seismic landslides. As the largest earthquake recorded in the Qujiang fault zone, the study on the coseismic landslides triggered by this earthquake are of great significance to the prevention and mitigation of earthquake-induced landslides in this region. In this study, we established a coseismic landslide inventory for the VⅢ–X seismic intensity areas of the Ms 7.7 Tonghai earthquake, and conducted spatial analysis on the coseismic landslides, mainly having analyzed the effect of the topographic factors, geological factors, and seismic factors on the development of the coseismic landslides. To enhance the understanding of this earthquake, we converted the earthquake epicenter and magnitude with empirical formulas based on the distributions and areas of the coseismic landslides. Comparing with coseismic landslides in other earthquake-hit areas, we found the capability that this earthquake could induce landslides is low. This study provides a useful supplement to the global coseismic landslide inventories and could be the basic data for seismic landslide assessment in this earthquake-prone region.

关键词： 1970 Tonghai Ms 7.7 earthquake Coseismic landslides Landslide inventory Spatial analysis Tectonic significance