Experimental assessment of textured tools with nano-lubricants in orthogonal cutting of titanium alloy

Gaofeng Zhang,Bingxing Chen,Gaocan Wu,Guoguang Xie,Hui Xie 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

In this study, we investigated the effects of composite nano-Cu/WS 2 lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool’s rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS 2 lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS 2 lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions.

Monitoring for Damage in Two-Dimensional Pre-Stress Scratching of SiC Ceramics

Gaofeng Zhang,Yijiang Zeng,Wenbo Zhang,Houming Zhou,Zhangya Wen,Yuan Yao 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.11

This paper reports an approach to use the acoustic emission (AE) technology for monitoring the surface/subsurface damage in twodimensional pre-stress scratching of SiC ceramics, in which the two-dimensional pre-stress is used to decrease the scratch-induced damage. Experiments in this study were conducted on a UMT-2 machine (CETR USA) utilizing a designed pre-stressing device under pressures of 0 MPa, 300 MPa and 500 MPa. The experimental results demonstrate that average frequency and magnitude of AE signals have a good correlation with the scratching tangential force and the scratch-induced surface /subsurface damage of materials. For a given normal load, the average frequency and magnitude of AE signals are observed to decrease with the increase in pre-stress, which indicates that surface/subsurface damage of SiC ceramics induced by two-dimensional pre-stress scratching is less than that induced by conventional scratching. The findings provide fundamental information for developing a practical on-line AE monitoring system that is effective in detecting surface/subsurface damage in scratching or grinding of ceramics. These results also demonstrate that two-dimensional pre-stress method contributes to decreasing the machining damage of brittle materials.

Single-Point Grinding of Alumina and Zirconia Ceramics Under Two-Dimensional Compressive Prestress

Gaofeng Zhang,Zhigang Wang,Wenxin Chen,Jingtao Li,Hao Sun,Kui Zhang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.1

In this study, single-point grinding experiments were performed on alumina and zirconia ceramics to investigate the grinding processes under two-dimensional compressive prestress (TCP). Grinding forces and grooves were measured under different values of TCP to evaluate the grinding defects. The material removal rate and actual grinding depth were exploited to investigate the grinding-induced damage and material

Security Performance Analysis of DF Cooperative Relay Networks over Nakagami-m Fading Channels

( Huan Zhang ),( Hongjiang Lei ),( Imran Shafique Ansari ),( Gaofeng Pan ),( Khalid A. Qaraqe ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.5

In this paper, we investigate the security performance for cooperative networks over Nakagami-m fading channels. Based on whether the channel state information (CSI) of wiretap link is available or not, optimal relay selection (ORS) and suboptimal relay selection (SRS) schemes are considered. Also, multiple relays combining (MRC) scheme is considered for comparison purpose. The exact and asymptotic closed-form expressions for secrecy outage probability (SOP) are derived and simulations are presented to validate the accuracy of our proposed analytical results. The numerical results illustrate that the ORS is the best scheme and SRS scheme is better than MRC scheme in some special scenarios such as when the destination is far away from the relays. Furthermore, through asymptotic analysis, we obtain the closed-form expressions for the secrecy diversity order and secrecy array gain for the three different selection schemes. The secrecy diversity order is closely related to the number of relays and fading parameter between relay and destination.

Recycling of Sintered Nd-Fe-B Magnets Doped with PrNd Nanoparticles

Xuefeng Zhang,Fei Liu,Yanli Liu,Qiang Ma,Yongfeng Li,Qian Zhao,Gaofeng Wang,Zhubai Li 한국자기학회 2015 Journal of Magnetics Vol.20 No.2

The waste of sintered Nd-Fe-B magnets was recycled using the method of dopingPrNd nanoparticles. The effect of PrNd nanoparticle doping on the magnetic properties of the regenerated magnets has been studied. As the content of the PrNd nanoparticles increases, the coercivity increases monotonically, whereas both the remanence and the maximum energy products reach the maximum values for 4 wt% PrNd doping. Microstructural observation reveals that the appropriate addition of PrNd nanoparticles improves the magnetic properties and refines the grain. Domain investigation shows that the self-pinning effect of the rare earth (Re)-rich phase is enhanced by PrNd nano-particle doping. Compared to the magnet with 4 wt% PrNd alloy prepared using the dual-alloy method, the regenerated magnet doped with the same number of PrNd nanoparticles exhibits better magnetic properties and a more homogeneous microstructure. Therefore, it is concluded that PrNd nanoparticle doping is an efficient method for recycling the leftover scraps of Nd-Fe-B magnets.

Abnormalities in Inflammatory Cytokines Confer Susceptible to Chronic Neuropathic Pain-related Anhedonia in a Rat Model of Spared Nerve Injury

Xi Fang,Gaofeng Zhan,Jie Zhang,Hui Xu,Bin Zhu,Yimin Hu,Chun Yang,Ailin Luo 대한정신약물학회 2019 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.17 No.2

Objective: Patients with chronic neuropathic pain (CNP) have a higher incidence to develop depression. However, its pathogenesis has not yet been fully elucidated. Here we aimed to investigate the role of inflammatory cytokines in CNP-related anhedonia, which is a core symptom of depression, and to explore the effects of ketamine and parecoxib on pain and anhedonia. Methods: A rat model of spared nerve injury (SNI) was constructed to mimic CNP. Hierarchical cluster analysis of sucrose preference test (SPT) was applied to classify the SNI rats into anhedonia susceptible and unsusceptible. Inflammatory cytokines in medial prefrontal cortex (mPFC) of brain, serum and L2-5 spinal cord were measured. Moreover, effects of ketamine or parecoxib on mechanical withdrawal test (MWT) and SPT in anhedonia susceptible rats were detected. Results: Tumor necrosis factor (TNF)- was increased in mPFC, serum and and spinal cord of anhedonia susceptible rats. Furthermore, anhedonia susceptible and unsusceptible rats both increased the interleukin (IL)-1 level in mPFC, serum and spinal cord. IL-6 was altered in serum and spinal cord, but not in mPFC. IL-10 was significantly altered in mPFC and serum, but not in spinal cord. Additionally, ketamine treatment significantly attenuated the decreased results of MWT and SPT in anhedonia susceptible rats, and that parecoxib significantly improved the MWT score, but failed to alter the result of SPT. Conclusion: These findings suggest that abnormalities in inflammatory cytokines confer susceptible to anhedonia in a rat model of SNI. Ketamine, a fast-acting antidepressant, has pharmacological benefits to alleviate pain and anhedonia symptoms.

The Research of Digital Forensics Technologies under Cloud Computing Environment

Huan Ma,Gaofeng Shen,Ming Chen,Jianwei Zhang 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.3

As the time of cloud computing comes, Cloud computing is estimated to be one of the most transformative technologies in the history of computing. Cloud organizations, including the providers and customers of cloud services, have yet to establish a well-defined forensic capability. Computer cybercrime has become very prominent forms of crime, but the traditional forensic methods have not met the requirements of the new digital forensics environment. In this paper, upon the use of cloud computing resource sharing, storage distribution and other characteristics and based on the analysis of cloud computing environments difficulties on digital forensics, new digital forensics methods and new digital forensics architecture in the cloud-based platform are proposes to meet rapid forensics needs in the era of cloud computing and to deal with the effectiveness, usefulness, depth issues and real-time and reliability problems.

Enhanced bone regeneration using poly(trimethylene carbonate)/ vancomycin hydrochloride porous microsphere scaffolds in presence of the silane coupling agent modified hydroxyapatite nanoparticles

Jian He,Xulin Hu,Luyao Xing,Dongliang Chen,Lijun Peng,Gaofeng Liang,Chengdong Xiong,Xiangchun Zhang,Lifang Zhang 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.99 No.-

Tissue-engineered scaffolds acted as active natural extracellular matrices that allowed for cellattachment, migration, proliferation, and differentiation. To enhance the drug loading, degradationcontrol, and mechanical features of tissue-engineered scaffolds used in bone regeneration applications,we synthesized novel poly(trimethylene carbonate) (PTMC)/modified HA nanoparticles (KHA NPs,modified by silane coupling agent)/vancomycin hydrochloride (VH) porous microspheres scaffold. Thefabricated PTMC/KHA/VH scaffold has unique surface corrosion degradation, excellent surface properties,and high cytocompatibility. The novel PTMC/KHA/VH scaffold was characterized by 42% porosity,100 mmpore size, and 208.2 MPa compressive modulus. After the treatment of a rat femur defect for 4, 8, and 12weeks, the surface corrosion biodegraded of the PTMC/KHA/VH scaffold remarkably decreasedinflammation response and promoted bone regeneration, suggesting its use as a bioactive structurein bone tissue engineering.