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Surface organic modification of Fe_3O_4 nanoparticles by silane-coupling agents

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Rare Metals 2006年第Z1期25卷 426-430页

作者： CUI Sheng SHEN xiaodong lin Benlan College of Material Science and Technology Nanjing University of Technology Nanjing 210009 China College of Material Science and Technology Nanjing University of Technology Nanjing 210009 China College of Material Science and Technology Nanjing University of Technology Nanjing 210009 China

Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in organic medium glycol were gained and the mean size of Fe3O4 nanopowders was 33.7 nm. So it can be concluded that magnetic micro-sphere is made of a few Fe3O4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe3O4 and the content of KH570. The modification of Fe3O4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe3O4 and KH570. When the content of Fe3O4 is known, there is a suitable content of KH570. Different content of Fe3O4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe3O4 surface or in the solution.

关键词： Fe3O4 nanoparticles organic modification silane-coupling agents

Multiphysics simulation method of Lamb wavepropagation with piezoelectric transducers under load condition

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Chinese Journal of Aeronautics 2019年第5期32卷 1071-1086页

作者： Lei QIU Xixi YAN xiaodong lin Shenfang YUAN Research Center of Structural Health Monitoring and Prognosis State Key Lab of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

Lamb Wave(LW) simulation under time-varying conditions is an effective and low cost way to study the problem of the low reliability of the structural health monitoring methods based on the LW and Piezoelectric Transducer(PT). In this paper, a multiphysics simulation method of the LW propagation with the PTs under load condition is proposed. With this method, two key mechanisms of the load influence on the LW propagation are considered and coupled with each other. The first mechanism is the acoustoelastic effect which is the main reason of the LW velocity change. The second key mechanism is the load influence on piezoelectric materials, which results in a change of the amplitude. Based on the computational platform of the COMSOL Multiphysics, a multiphysics simulation model of the LW propagation with the PTs under load condition is established. The simulation model includes two physical phenomena. The first one is called solid mechanics, which is used to simulate the acoustoelastic effect being combined with the hyperelastic material properties of the structure in which the LW propagates. The second one is called electromechanical coupling, which considers the simulation of the piezoelectric effect of the PTs for the LW excitation and sensing. To simulate the load influence on piezoelectric materials, a non-linear numerical model of the relationship between the load and the piezoelectric coefficient d31 is established based on an experiment of the load influence on the LW. The simulation results under uniaxial tensile load condition are obtained and are compared with the data obtained from the experiment. It shows that the variations of the phase velocity and amplitude of the LW obtained from the simulation model match the experimental results well.

关键词： Acoustoelastic effect Lamb wave Multiphysics simulation Piezoelectric coefficient Structural health monitoring Time-varying condition

Deformation and cracking behaviors of proton-irradiated 308L stainless steel weld metal strained in simulated PWR primary water

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Journal of Materials Science & Technology 2022年第25期120卷 36-52页

作者： xiaodong lin Qunjia Peng En-Hou Han Wei Ke Institute of Materials Shanghai UniversityShanghai 200072China Suzhou Nuclear Power Research Institute Suzhou 215004China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The proton-irradiated 308L stainless steel weld metal was strained by using constant extension rate tensile testing in simulated PWR primary water, and its deformation microstructures and irradiation assisted stress corrosion cracking(IASCC) behavior were investigated. The results suggest that the irradiation significantly increases the SCC susceptibility of 308L weld metal and causes various deformation microstructures including lathy faulted planes, dislocation channels and deformation twins in austenite and atomic plane rotation in δ-ferrite. The propagation of intergranular IASCC cracks is closely related to the location of the crack tip. For the crack tip in the specimen matrix interior, localized deformation is likely the key factor responsible for the crack growth. For the crack tip close to the specimen surface, however, localized corrosion along the grain boundary rather than the localized deformation appears to dominate the crack propagation. Unlike the intergranular cracks, the IASCC cracks along the δ-ferrite/austenite phase boundary can initiate either by crack initiation at the phase boundary or by crack propagation from the grain boundary. In both cases, the cracked phase boundaries contain a large number of carbides and are severely corroded, but no deformation microstructures are observed, which implies that the localized corrosion may play an important role in the IASCC along the phase boundary. In addition, δ-ferrite can retard the IASCC crack propagation along the grain boundary, which is probably related to the reduction of localized deformation by δ-ferrite.

关键词： Stainless steel weld metal Proton irradiation Deformation microstructures Irradiation assisted stress corrosion cracking Grain and phase boundaries

Effect of thermal ageing and dissolved gas on corrosion of 308L stainless steel weld metal in simulated PWR primary water

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Journal of Materials Science & Technology 2022年第1期96卷 308-324页

作者： xiaodong lin Qunjia Peng Yaolei Han En-Hou Han Wei Ke Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Suzhou Nuclear Power Research Institute Suzhou 215004China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Institute of Materials Shanghai UniversityShanghai 200072China

The corrosion of unaged and 7000-h thermally aged 308 L stainless steel weld metals in simulated PWR primary water under aerated and deaerated conditions was investigated,involving the corrosion of austenite,δ-ferrite andδ-ferrite/austenite phase *** results revealed that thermal ageing for 7000 h had a limited effect on the corrosion behavior of 308 L weld metal as it only increased the inner oxide thickness ofδ-ferrite slightly under the deaerated *** obvious corrosion enhancement of 308 L weld metal under the aerated condition was found compared to the deaerated condition regardless of the thermal ***,Cr-enrichment on the surface of oxide particles,dissolved regions at the metal/oxide interface and localized corrosion along theδ-ferrite/austenite phase boundary occurred under the aerated condition.

关键词： Stainless steel weld metal Thermal ageing Corrosion High temperature water TEM

Interactive effect of thermal aging and proton irradiation on microstructural evolution and hardening ofδ-ferrite in 308L stainless steel weld metal

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Journal of Materials Science & Technology 2024年第3期170卷 140-155页

作者： xiaodong Gao xiaodong lin Tao Guo lining Xu Yaolei Han Baolong Jiang Xingyuan Mei Qunjia Peng Lijie Qiao Beijing Advanced Innovation Center for Materials Genome Engineering Institute of Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China Institute of Materials Shanghai UniversityShanghai 200072China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Suzhou Nuclear Power Research Institute Suzhou 215004China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

In the harsh service environment of high temperature and intense neutron irradiation in water-cooled nuclear reactors,the austenitic stainless steel weld overlay cladding on the inner surface of the reactor pressure vessel suffers from thermal aging and irradiation damage simultaneously,which can induce microstructural evolution and hardening of the *** it is quite difficult to achieve this simul-taneous process out of the pile,two kinds of combined experiments,i.e.,post-irradiation thermal aging and post-aging irradiation were performed on 308 L stainless steel weld metals in this *** interactive effect of thermal aging and proton irradiation on microstructural evolution and hardening ofδ-ferrite in 308 L weld metal was investigated by combining atom probe tomography,transmission elec-tron microscopy and nanoindentation *** results revealed that thermal aging could eliminate the dislocation loops induced by irradiation and affect the phase transition process by accelerating spinodal decomposition and G-phase precipitation,thus enhancing hardening of irradiatedδ-*** the effect of irradiation on the microstructure and hardening of thermally agedδ-ferrite,however,intensive collision cascades can intensify G-phase precipitation and dislocation loop formation but decrease spinodal decomposition,leading to a limited effect on hardening of thermally agedδ-***,the interaction of thermal aging and irradiation can promote G-phase ***,the interaction can causeδ-ferrite hardening,which is mainly influenced by spinodal decomposition,followed by G-phase and dislocation loops,where spinodal decomposition and G-phase cause hardening by inducing strain fields.

关键词： Austenitic stainless steel weld metals Thermal aging Proton irradiation Interaction Microstructural evolution Hardening

Study of magneto-optical effects in γ-Fe_2O_3/ZnFe_2O_4 nanoparticle ferrofluids, using circularly polarized light

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Science China(Physics,Mechanics & Astronomy) 2012年第8期55卷 1404-1411页

作者： FU Jun LI Jian lin YueQiang LIU xiaodong MIAO Hua lin LiHua School of Physical Science & Technology MOE Key Laboratory on Luminescence and Real-Time Analysis Southwest University Chongqing 400715 China

When circularly polarized light travels through a ferrofluid film in the presence of an applied magnetic field, the transmitted light will behave as elliptically polarized light, because of magnetic birefringence and dichroism. The angular distribution of the relative intensity of the transmitted light can be obtained using a polarizer, so that the ratio of both the long and short ax- es-as well as the orientation angle of the ellipse, corresponding to the direction of the applied magnetic field--can be deter- mined, and whether the ferrofluids samples are stable during the measurement can be directly judged from the shape of the distribution curves. Thus, the ratio of the amplitudes Ax/Ay and the added phase difference A r can be resolved in the elliptically polarized light, and information on both the magnetic birefringence An and the dichroism Ak can be deduced for the ferrofluid sample. From the orientation angles of both right-handed and left-handed elliptically polarized transmitted light, the direction of the applied magnetic field can be accurately determined. Using circularly polarized light, the magnetic birefringence and dichroism of pure γ-Fe2O3 ferrofluids and γ--Fe2O3/ZnFe2O4 binary ferrofluids were studied. For the binary ferrofluids, a mod- ulating effect on the magnetic birefringence and dichroism was revealed.

关键词： ferrofluids polarization birefringence dichroism

XMAM:X-raying models with a matrix to reveal backdoor attacks for federated learning

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Digital Communications and Networks 2024年第4期10卷 1154-1167页

作者： Jianyi Zhang Fangjiao Zhang Qichao Jin Zhiqiang Wang xiaodong lin Xiali Hei Beijing Electronic Science and Technology Institute Beijing100070China University of Guelph OntarioN1G 2W1Canada University of Louisiana at Lafayette Louisiana70503USA

Federated Learning(FL),a burgeoning technology,has received increasing attention due to its privacy protection ***,the base algorithm FedAvg is vulnerable when it suffers from so-called backdoor *** researchers proposed several robust aggregation ***,due to the hidden characteristic of backdoor attacks,many of these aggregation methods are unable to defend against backdoor ***'s more,the attackers recently have proposed some hiding methods that further improve backdoor attacks'stealthiness,making all the existing robust aggregation methods *** tackle the threat of backdoor attacks,we propose a new aggregation method,X-raying Models with A Matrix(XMAM),to reveal the malicious local model updates submitted by the backdoor *** we observe that the output of the Softmax layer exhibits distinguishable patterns between malicious and benign updates,unlike the existing aggregation algorithms,we focus on the Softmax layer's output in which the backdoor attackers are difficult to hide their malicious ***,like medical X-ray examinations,we investigate the collected local model updates by using a matrix as an input to get their Softmax layer's ***,we preclude updates whose outputs are abnormal by *** any training dataset in the server,the extensive evaluations show that our XMAM can effectively distinguish malicious local model updates from benign *** instance,when other methods fail to defend against the backdoor attacks at no more than 20%malicious clients,our method can tolerate 45%malicious clients in the black-box mode and about 30%in Projected Gradient Descent(PGD)***,under adaptive attacks,the results demonstrate that XMAM can still complete the global model training task even when there are 40%malicious ***,we analyze our method's screening complexity and compare the real screening time with other *** results show that XMAM is a

关键词： Federated learning Backdoor attacks Aggregation methods

Modulation response performances of a Fabry-Perot semiconductor laser subjected to light injection from another Fabry-Perot semiconductor laser

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Chinese Science Bulletin 2009年第20期54卷 3643-3648页

作者： XIA GuangQiong WU ZhengMao YANG Qi lin xiaodong School of Physics Southwest University Chongqing 400715 China State Key Laboratory of Millimeter Waves Southeast University Nanjing 210096 China

The modulation response characteristics of a Fabry-Perot semiconductor laser(slave FP-LD) subjected to light injection from another Fabry-Perot semiconductor laser(master FP-LD) have been investigated *** results show that the modulation response performances of the slave FP-LD depend on the light injection strength,the central mode frequency detuning Δf and the mode spacing difference Δλ between the slave FP-LD and the master *** the increase of the light injection strength from the master FP-LD,the 3 dB modulation bandwidth of the slave FP-LD will be enhanced;however,if the injection strength is increased to certain degree,the front side of the relaxation oscillation peak will be reduced to below 3 dB,which results in the rapid decrease of the 3 dB modulation *** the increase of Δf,for a relatively small injection strength level,the 3 dB modulation bandwidth will behave a monotonous enlargement until the slave FP-LD operates in a period-one state(P1).For a relatively strong optical injection level,the slave FP-LD has a broad injection-locked frequency detuning *** the injection-locked area,with the increase of frequency detuning Δf,the 3dB modulation bandwidth increases at first and then decreases after experiencing a maximum *** given light injection strength and frequency detuning,the 3 dB modulation bandwidth of the slave FP-LD has two maximums and behaves a symmetrical distribution with the change of Δλ.By choosing reasonable parameters,the 3 dB modulation bandwidth can be significantly *** the parameter values selected in this paper,the 3 dB modulation bandwidth can increase 5.5 times compared with the case of free running.

关键词：半导体激光器注射曝光表演调制

Secure and Privacy-Preserving Decision Tree Classification with Lower Complexity

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Journal of Communications and Information Networks 2020年第1期5卷 16-25页

作者： Liang Xue Dongxiao Liu Cheng Huang xiaodong lin Xuemin(Sherman)Shen Department of Electrical and Computer Engineering University of WaterlooWaterloo N2L 3G1Canada School of Computer Science University of GuelphGuelph N1G 2W1Canada Department of Electrical and Computer EngineeringUniversity of WaterlooWaterloo N2L 3G1Canada

As a widely-used machine-learning classifier,a decision tree model can be trained and deployed at a service provider to provide classification services for clients,e.g.,remote *** address privacy concerns regarding the sensitive information in these services(i.e.,the clients’inputs,model parameters,and classification results),we propose a privacy-preserving decision tree classification scheme(PDTC)in this ***,we first tailor an additively homomorphic encryption primitive and a secret sharing technique to design a new secure two-party comparison protocol,where the numeric inputs of each party can be privately compared as a whole instead of doing that in a bit-by-bit ***,based on the comparison protocol,we exploit the structure of the decision tree to construct PDTC,where the input of a client and the model parameters of a service provider are concealed from the counterparty and the classification result is only revealed to the client.A formal simulation-based security model and the security proof demonstrate that PDTC achieves desirable security *** addition,performance evaluation shows that PDTC achieves a lower communication and computation overhead compared with existing schemes.

关键词： decision trees data privacy model privacy secure comparison machine-learning classification