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T5处理对高真空压铸Al-10Si-Cu-Mg-Mn合金组织影响

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特种铸造及有色合金 2024年第5期44卷 669-674页

作者：刘金辉赵海东高军民李史华侯小华华南理工大学国家金属材料近净成形工程技术研究中心广州510640 文灿集团股份有限公司广州523000

采用高真空压铸制备了不同Cu含量的AlSi10CuMgMn合金,采用光学显微镜(OM)、扫描电镜(SEM)和透射电镜(TEM)对铸态和T5态合金微观组织进行研究。结果表明,不同Cu含量下,铸态合金组织由α-Al、共晶Si和α-Fe、Q和θ相组成。随着Cu含量增加,... 详细信息

采用高真空压铸制备了不同Cu含量的AlSi10CuMgMn合金,采用光学显微镜(OM)、扫描电镜(SEM)和透射电镜(TEM)对铸态和T5态合金微观组织进行研究。结果表明,不同Cu含量下,铸态合金组织由α-Al、共晶Si和α-Fe、Q和θ相组成。随着Cu含量增加,Q相数量变化不大,形貌以层片状为主;θ相数量则逐渐增多,形貌由分散的粒状转变成聚集的块状。T5热处理不会改变相的类型和形貌,峰值时效时主要析出相为β"和θ’相,Cu含量较低时,析出相以β"相为主,Cu含量较高时,析出相以θ’相为主。

关键词： AlSi10CuMgMn合金高真空压铸 T5热处理微观组织

Measuring Thermal Conductivity of an Individual Carbon Nanotube Using Raman Spectroscopy

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Journal of Thermal Science 2022年第4期31卷 1016-1022页

作者： LI Pei FENG Daili FENG Yanhui liu Xiaofang XIONG Mengya ZHANG Xinxin liu jinhui School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry University of Science and Technology BeijingBeijing 100083China Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China

In this paper,a non-contact method based on Raman spectroscopy was used to measure the thermal conductivity of an individual single-walled carbon nanotube(SWCNT)and a multi-walled carbon nanotube(MWCNT).The effect of laser-induced heating on carbon nanotubes(CNTs)was *** local temperatures along the longitudinal direction of carbon nanotube were determined by Raman shift,combined with one-dimensional heat conduction model,and the thermal conductivity was finally *** thermal conductivity of the SWCNT with a length of 25μm and a diameter of 1.34 nm decreases as the temperature increases in the measuring temperature range(316 K–378 K).The corresponding thermal conductivities change from 1651 W/(m·K)to 2423 W/(m·K);the thermal conductivities of the MWCNT with 40μm length and 9.2 nm diameter are within 1109–1700 W/(m·K)at 316 K–445 *** further analyze the size effect on the thermal conductivity,molecular dynamics simulation has been carried *** result shows that the thermal conductivity of an individual carbon nanotube increases with increasing nanotube length and eventually *** work is expected to provide some reference data for the studies of thermal properties of individual CNTs.

关键词： carbon nanotube thermal conductivity Raman spectroscopy molecular dynamics

An investigation on micro pore structures and the vapor pressure mechanism of explosive spalling of RPC exposed to high temperature

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Science China(Technological Sciences) 2013年第2期56卷 458-470页

作者： JU Yang liu HongBin TIAN KaiPei liu jinhui WANG Li GE ZhiShun State Key Laboratory of Coal Resources and Safe Mining China University of Mining and Technology Beijing Key Laboratory of Fracture and Damage Mechanics of Rocks and Concrete China University of Mining and Technology School of Mechanics and Civil Engineering China University of Mining and Technology

Reactive powder concrete （RPC） is vulnerable to explosive spalling when exposed to high temperature. The characteristics of micro pore structure and vapor pressure of RPC are closely related to the thermal spalling. Applying mercury intrusion po- rosimetry （MIP） and scanning electron microscopy （SEM） techniques, the authors probed the characteristics of micro pore structures of plain RPC200 when heated from 20-350~C. The pore characteristics such as specific pore volume, threshold pore size and most probable pore size varying with temperatures were investigated. A vapor pressure kit was developed to measure the vapor pressure and its variation inside RPC200 at various temperatures. A thin-wall spherical pore model was proposed to ana- lyze the thermo-mechanical mechanism of spalling, by which the stresses varying with the vapor pressure q（T） and the character- istic size of wall （K） at any point of interest were determined. It is shown that the pore characteristics including specific pore volume, average pore size, threshold pore size and most probable pore size rise significantly with the increasing temperature. 200~C appears to be the threshold temperature above which the threshold pore size and the most probable pore size climb up dramatically. The increase in the specific pore volume results from the growth both in quantity and in volume of the transition pores and the capillary pores. The appearance of the explosive spalling in RPC200 is mainly attributed to being unable to form pathways in favor of releasing water steam in RPC and to thin-wall sphere domain where the vapor pressure governs the the rapid accumulation of high vapor pressures as well. The spalling is bounded through the pore model.

关键词： reactive powder concrete (RPC) high temperature spalling pore structure vapor pressure microstructures mercuryintrusion porosimetry (MIP)

新疆512矿床砂岩型铀矿孔隙特征及渗流模拟

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地质科技通报 2024年第4期43卷 205-218页

作者：刘亚玲黎广荣周义朋孙占学赵凯刘金辉徐玲玲东华理工大学核资源与环境国家重点实验室南昌330013 东华理工大学地球科学学院南昌330013

地浸采铀工艺是溶浸液在含矿含水层中与铀矿物发生反应,铀元素随溶浸液迁移至地表的一种提铀工艺,精确了解矿区岩石内部结构及金属矿物的分布,对地浸工艺应用具有重要的指导意义。为了解512矿床岩石内部结构及渗流路径,选取该矿床代表... 详细信息

地浸采铀工艺是溶浸液在含矿含水层中与铀矿物发生反应,铀元素随溶浸液迁移至地表的一种提铀工艺,精确了解矿区岩石内部结构及金属矿物的分布,对地浸工艺应用具有重要的指导意义。为了解512矿床岩石内部结构及渗流路径,选取该矿床代表性围岩和矿石岩心进行CT扫描,经过图像降噪滤波、图像分割提取孔隙、构建孔隙网络模型等处理与分析,获得各孔喉参数;通过Avizo软件模拟得到绝对渗透率、迂曲率和渗流速度变化。结果表明:围岩和矿石的孔隙度相近,分别为15.42%,15.18%;连通孔隙度分别是9.61%,13.82%。围岩中高密度物质为一些金属矿物,体积分数约为0.54%,矿石中高密度矿物多为次生铀矿物,体积分数为1.06%,其在浸出过程中可与溶浸液充分接触。孔隙内部具有强烈的非均质性,导致流速在流动路径中逐渐降低。围岩和矿石连通的大孔数量多于小孔,指示大孔是决定孔隙发育程度的主要因素。根据速度流线推断围岩和矿石中虽然存在堵塞区,但流通区域占主导地位。

关键词：砂岩型铀矿地浸采铀 CT扫描孔隙特征渗流模拟新疆512矿床

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A public key cryptosystem based on data complexity under quantum environment

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Science China(Information Sciences) 2015年第11期58卷 48-58页

作者： WU WanQing ZHANG HuanGuo WANG HouZhen MAO ShaoWu JIA JianWei liu jinhui Computer School Wuhan University

Since the Shor algorithm showed that a quantum algorithm can efficiently calculate discrete logarithms and factorize integers, it has been used to break the RSA, EIGamal, and ECC classical public key cryptosystems. This is therefore a significant issue in the context of ensuring communication security over insecure channels. In this paper, we prove that there are no polynomial-size quantum circuits that can compute all Boolean functions(of which there are 22ncases) in the standard quantum oracle model. Based on this,we propose the notion of data complexity under a quantum environment and suggest that it can be used as a condition for post-quantum computation. It is generally believed that NP-complete problems cannot be solved in polynomial time even with quantum computers. Therefore, a public key cryptosystem and signature scheme based on the difficulty of NP-complete problems and the notion of data complexity are presented here. Finally,we analyze the security of the proposed encryption and signature schemes.

关键词： public key cryptography information security NP-complete problem complexity theory quantum computation

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内蒙古芒来铀矿石酸法柱浸试验

东华理工大学学报（自然科学版） 2024年第2期47卷 185-192页

作者：刘金辉刘昕瑀阳奕汉邢拥国王如意梁大业闫学锐吴怡娴东华理工大学水资源与环境工程学院江西南昌330013 中核内蒙古矿业有限公司内蒙古呼和浩特014000 中国铀业有限公司北京100013

为获得溶浸液在不同硫酸质量浓度条件下的铀浸出特征及试验参数,探究内蒙古芒来铀矿床矿石酸法浸出的可行性,开展了不同硫酸质量浓度(5、10、15、20 g/L)的溶浸液下室内柱浸浸铀试验。试验结果表明,随着溶浸液硫酸质量浓度的增高,浸出... 详细信息

为获得溶浸液在不同硫酸质量浓度条件下的铀浸出特征及试验参数,探究内蒙古芒来铀矿床矿石酸法浸出的可行性,开展了不同硫酸质量浓度(5、10、15、20 g/L)的溶浸液下室内柱浸浸铀试验。试验结果表明,随着溶浸液硫酸质量浓度的增高,浸出液铀质量浓度及铀浸出率随之增高,浸出周期缩短,故酸法工艺适合该矿床铀浸出。试验后期浸出液流量降低与长石类矿物的黏土化蚀变有关。针对铀平均品位为8.8×10^(-5)的矿石,铀浸出率为49.80%~54.35%,从浸出率、防堵塞及浸铀成本等方面综合分析,认为质量浓度为10 g/L的硫酸溶浸液较适合该铀矿酸法地浸开采。

关键词：砂岩型铀矿床酸法浸出柱浸试验长石黏土化芒来

Cryptanalysis of an asymmetric cipher protocol using a matrix decomposition problem

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Science China(Information Sciences) 2016年第5期59卷 133-143页

作者： jinhui liu Huanguo ZHANG Jianwei JIA Houzhen WANG Shaowu MAO Wanqing WU Computer School of Wuhan University Key Laboratory of Aerospace Information security and trusted computing Ministry of Education

Advances in quantum computation threaten to break public key cryptosystems such as RSA, ECC,and El Gamal that are based on the difficulty of factorization or taking a discrete logarithm, although up to now,no quantum algorithms have been found to be able to solve certain mathematical problems on non-commutative algebraic structures. Against this background, Raulynaitis et al. have proposed a novel asymmetric cipher protocol using a matrix decomposition problem. Their proposed scheme is vulnerable to a linear algebra attack based on the probable occurrence of weak keys in the generation process. In this paper, we show that the asymmetric cipher of the non-commutative cryptography scheme is vulnerable to a linear algebra attack and that it only requires polynomial time to obtain the equivalent keys for some given public keys. We also propose an improvement to enhance the scheme of Raulynaitis et al.

关键词： cryptography post-quantum computational cryptography asymmetric cipher protocol cryptanalysis matrix decomposition

Cryptanalysis of Public Key Cryptosystems Based on Non-Abelian Factorization Problems

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Tsinghua Science and Technology 2016年第3期21卷 344-351页

作者： jinhui liu Aiwan Fan Jianwei Jia Huanguo Zhang Houzhen Wang Shaowu Mao Computer School of Wuhan University Wuhan 430072China Computer School of Pingdingshan University Pingdingshan 467001China

Advances in quantum computers threaten to break public-key cryptosystems （e.g., RSA, ECC, and EIGamal）, based on the hardness of factoring or taking a discrete logarithm. However, no quantum algorithms have yet been found for solving certain mathematical problems in non-commutative algebraic structures. Recently, two novel public-key encryption schemes, BKT-B cryptosystem and BKT-FO cryptosystem, based on factorization problems have been proposed at Security and Communication Networks in 2013. In this paper we show that these two schemes are vulnerable to structural attacks and linearization equations attacks, and that they only require polynomial time complexity to obtain messages from associated public keys. We conduct a detailed analysis of the two attack methods and show corresponding algorithmic descriptions and efficiency analyses. In addition, we provide some improvement suggestions for the two public-key encryption schemes.

关键词： cryptography post-quantum cryptography public key encryption cryptanalysis linear equations

Non-Fourier heat conduction study for steady states in metallic nanofilms

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Chinese Science Bulletin 2012年第24期57卷 3239-3243页

作者： WANG HaiDong liu jinhui GUO ZengYuan TAKAHASHI Koji Key Laboratory for Thermal Science and Power Engineering of Ministry of Education School of AerospaceTsinghua UniversityBeijing 100084China Graduate School of Engineering Kyushu UniversityFukuoka 819-0395Japan

As a fundamental theory of heat transfer, Fourier's law is valid for most traditional conditions. Research interest in non-Fourier heat conditions is mainly focused on heat wave phenomena in non-steady states. Recently, the thermomass theory posited that, for steady states, non-Fourier heat conduction behavior could also be observed under ultra-high heat flux conditions at low ambient temperatures. Significantly, this is due to thermomass inertia. We report on heat conduction in metallic nanofilms from large currents at low temperatures; heat fluxes of more than 1×1010 W m 2 were used. The measured average temperature of the nanofilm is larger than that based on Fourier's law, with temperature differences increasing as heat flux increased and ambient temperature decreased. Experimental results for different film samples at different ambient temperatures reveal that non-Fourier behavior exists in metallic nanofilms in agreement with predictions from thermomass theory.

关键词：非傅立叶热传导非稳定状态纳米薄膜金属低环境温度 Fourier 傅立叶定律高热通量