Cutting parameters optimization for MRR under the constraints of surface roughness and cutter breakage in micro-milling process

Xiaohong Lu,Haixing Zhang,Zhen-yuan Jia,Yixuan Feng,Steven Y. Liang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7

Selection of cutting parameters in micro-milling operations is essential for improving machining efficiency and quality, and prolonging the micro-milling tool life. The increase of material removal rate (MRR) always means the increase of cutting parameters, which may lead to poor surface quality and micro-milling tool failure, even cutter breakage. An optimization approach based on genetic algorithm is used to achieve the maximum MRR under the constraints of surface roughness and cutter breakage. A theoretical model for predicting micro-milling cutter breakage is presented and micro-milling experiments were conducted to establish statistical models of cutter breakage and surface roughness. The optimized results were achieved under the constraints of the specified surface roughness and compared under the different surface roughness limitation. We find that the optimized results improve the machining efficiency and quality in micro-milling and is affected by constraint conditions complicatedly.

Prediction model of the surface roughness of micro-milling single crystal copper

Xiaohong Lu,Liang Xue,Feixiang Ruan,Kun Yang,Steven Y. Liang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11

Presently, the demand for single crystal copper micro-components is increasing in various fields because single crystal copper has good electrical conductivity. Micro-milling technology is an effective processing technology for small single crystal copper parts. Surface roughness is a key performance indicator for micro-milling single crystal copper. Establishing a surface roughness prediction model with high precision is useful to guarantee the processing quality by selecting the cutting parameters for micro-milling. Few studies have currently focused on micro-milling single crystal copper. In this study, the orthogonal experiments of micro-milling single crystal copper were conducted, and the influences of the spindle and feed speeds and axial depth of cut on the surface roughness of micro-milled single crystal copper with different orientations were analyzed by range analyses. The spindle rotation speed was the major affecting factor. The surface roughness of single crystal copper in different crystal orientations was predicted by using the SVM method. Experimental results showed that the average relative error of the surface roughness of <100>, <110>, and <111> crystal orientation single crystal copper was 2.7 %, 3.3 %, and 2.2 %, respectively, and that the maximum relative errors were 7.0 %. 10.1 %, and 3.1 %, respectively. The uncertainty analysis was conducted by using the Monte Carlo method to verify the reliability of the built surface roughness model.

Inverse Analysis of Inconel 718 Laser-Assisted Milling to Achieve Machined Surface Roughness

Yixuan Feng,Tsung-Pin Hung,Yu-Ting Lu,Yu-Fu Lin,Fu-Chuan Hsu,Chiu-Feng Lin,Ying-Cheng Lu,Xiaohong Lu,Steven Y. Liang 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.11

This manuscript proposes an inverse analysis method for the machined surface roughness in laser-assisted milling on Inconel 718. The method solves the forward problem considering the tool profile and the elastic recovery of machined surface and applies the variance-based recursive method to guide the updating mechanism of process parameters to match the measurements. Subsequently, the inverse analysis identifies four process parameters of feed per tooth, tool tip radius, minimum cutting thickness, and tool tip angle, and finds the optimal solution for target performance, the surface roughness. The measurements are collected under the single beam coaxial laser-assisted milling spindle. The proposed modified Kalman filter algorithm introduces the gain coefficient G when updating the process parameters to improve robustness and accuracy. The inverse analysis is conducted on all measurements, and the average error of target performance is 0.460% when the laser is on and 0.394% when the laser is off. The average difference of process parameters is less than 5%, and the selection process is done in 50 loops within a minute. Therefore, the proposed inverse analysis model is robust, adaptive to different initial guesses and measurements, highly accurate, and saves computation time.

Mechanical and antibacterial properties of resin co-filled with mesoporous silica and graphene quantum dots

Lu Shuxin,Zhang Hongyu,Chai Maozhou,Yao Xiaohong,Zhang Xiangyu,Yang Yongqiang 한국탄소학회 2023 Carbon Letters Vol.33 No.2

Poor mechanical properties and bacterial infection are the main problems faced by dental restorative resins in clinical use. In this study, graphene quantum dots (GQDs) grafted with imidazole groups and mesoporous silica (MSN) are co-filled in a dental resin to impart excellent antimicrobial activity and mechanical properties to the dental resin. The higher specific surface area of GQDs and MSN results in an increased contact area with the resin matrix, which enhances the strength of the dental composite resin. The introduction of GQDs significantly improves the antimicrobial activity of the resin. The inhibition efficiency of the composite resin against Streptococcus mutans reached 99.9% with the addition of GQDs at only 0.2 wt.%. When MSN and GQDs are co-filled, MSN interferes with the release of GQDs, thus reducing the antimicrobial activity of the dental resin but improving the cyto-compatibility. By reasonably adjusting the amount of GQDs and MSN, the dental composite resin can exhibit excellent antimicrobial properties, mechanical properties and cyto-compatibility at the same time.

Research on flexible job-shop scheduling problem based on a modified genetic algorithm

Wei Sun,Ying Pan,Xiaohong Lu,Qinyi Ma 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.10

Aiming at the existing problems with GA (genetic algorithm) for solving a flexible job-shop scheduling problem (FJSP), such as description model disunity, complicated coding and decoding methods, a FJSP solution method based on GA is proposed in this paper, and job-shop scheduling problem (JSP) with partial flexibility and JIT (just-in-time) request is transformed into a general FJSP. Moreover, a unified mathematical model is given. Through the improvement of coding rules, decoding algorithm, crossover and mutation operators,the modified GA’s convergence and search efficiency have been enhanced. The example analysis proves the proposed methods can make FJSP converge to the optimal solution steadily, exactly, and efficiently.

The anti-tumor efficacy of 20(S)-protopanaxadiol, an active metabolite of ginseng, according to fasting on hepatocellular carcinoma

Wenzhen Li,YifanWang,Xinbo Zhou,Xiaohong Pan,Junhong Lu,Hongliu Sun,Zeping Xie,Shayan Chen,Xue Gao 고려인삼학회 2022 Journal of Ginseng Research Vol.46 No.1

Background: 20(S)-protopanaxadiol (20(S)-PPD), one of the main active metabolites of ginseng, performs a broad spectrum of anti-tumor effects. Our aims are to search out new strategies to enhance anti-tumor effects of natural products, including 20(S)-PPD. In recent years, fasting has been shown to be multifunctional on tumor progression. Here, the effects of fasting combined with 20(S)-PPD on hepatocellular carcinoma growth, apoptosis, migration, invasion and cell cycle were explored. Methods: CCK-8 assay, trypan blue dye exclusion test, imagings photographed by HoloMonitorTM M4, transwell assay and flow cytometry assay were performed for functional analyses on cell proliferation, morphology, migration, invasion, apoptosis, necrosis and cell cycle. The expressions of genes on protein levels were tested by western blot. Tumor-bearing mice were used to evaluate the effects of intermittent fasting combined with 20(S)-PPD. Results: We firstly confirmed that fasting-mimicking increased the anti-proliferation effect of 20(S)-PPD in human HepG2 cells in vitro. In fasting-mimicking culturing medium, the apoptosis and necrosis induced by 20(S)-PPD increased and more cells were arrested at G0-G1 phase. Meanwhile, invasion and migration of cells were decreased by down-regulating the expressions of matrix metalloproteinase (MMP)-2 and MMP-9 in fasting-mimicking medium. Furthermore, the in vivo study confirmed that intermittent fasting enhanced the tumor growth inhibition of 20(S)-PPD in H22 tumor-bearing mice without obvious side effects. Conclusion: Fasting significantly sensitized HCC cells to 20(S)-PPD in vivo and in vitro. These data indicated that dietary restriction can be one of the potential strategies of chinese medicine or its active metabolites against hepatocellular carcinoma.

Facile Fabrication of Superhydrophobic Cellulose/Fe2O3-STA Film with Nanoflower Morphologies for Heavy Oil Removal

Chang-Lian Xu,Shiyi Wang,Lu Zhou,Yiwen Bi,Gang Yang,Jun Wu,Xiaohong Zhang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.10

Heavy oils induced water pollutions are difficult to be eliminated due to the oils located under water. Herein, wefabricated superhydrophobic cellulose film with nanoflower structures via a Facile method to eliminate heavy oil from water. Cellulose films were in-situ modified with Fe2O3 and stearic acid (STA) for superhydrophobic modification. Thecorresponding superhydrophobic cellulose/Fe2O3-STA film has water contact angle of 155.5 º and sliding angle of 5.5 º, andcan maintains its superhydrophobicity when it is immersed in water. The film exists excellent self-cleaning property, and thedusts on the film could be easily swept away by running water drops. The film was further applied to separate heavy oil/watermixture with separation efficiency of 99.37 %, and the separation efficiency was maintained after 20 separation cycles aswell. The film can also be utilized to absorb small heavy oil drops under water. Thus, we not only develop a simple way toproduce superhydrophobic cellulose based films, but also provide superhydrophobic materials to solve water pollutioncaused by heavy oil.

Comparison of leaf transcriptomes of cassava “Xinxuan 048” diploid and autotetraploid plants

Ling Yin,Junjie Qu,Huiwen Zhou,Xiaohong Shang,Hui Fang,Jiang Lu,Huabing Yan 한국유전학회 2018 Genes & Genomics Vol.40 No.9

Polyploidy breeding of cassava has been used to improve cassava traits over the past years. We previously reported in vitro induction of tetraploids in the cassava variety “Xinxuan 048” using colchicine. Significant differences in morphology and anatomy were found between the diploid and tetraploid plants. However, very little is known about the transcriptome difference between them. In this study, morphological and physiological characteristics including leaf thickness, plant height, internode length, chlorophyll content, and photosynthetic capacity were measured. Further, we investigated and validated the difference in gene expression patterns between cassava “Xinxuan 048” tetraploid genotype and its diploid plants using RNA sequencing (RNAseq) and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Significant differences in morphology and physiology were observed during tetraploidization. A comparison revealed that tetraploidy induced very limited changes in the leaf transcriptomes of cassava “Xinxuan 048” diploid and autotetraploid plants. However, the differentially expressed genes (DEGs) between 2× and 4× plants, especially those upregulated in 4× plants, were strongly associated with hormonal and stress responses. Large changes in morphology and physiology between the diploid cassava “Xinxuan 048” and its autotetraploid were not associated with large changes in their leaf transcriptomes. Moreover, the differently expressed genes related to the regulation of gibberellin and brassinosteroids potentially explained why the plant height and internode length of 4× plants became shorter. Collectively, our results suggest that 4× cassava is potentially valuable for breeding strains with improved stress resistance.

Glutamic-oxaloacetic transaminase 1 regulates adipocyte differentiation by altering nicotinamide adenine dinucleotide phosphate content

Yang Yang,Cheng Zhimin,Zhang Wanfeng,Hei Wei,Lu Chang,Cai Chunbo,Zhao Yan,Gao Pengfei,Guo Xiaohong,Cao Guoqing,Li Bugao 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.2

Objective: This study was performed to examine whether the porcine glutamic-oxaloacetic transaminase 1 (GOT1) gene has important functions in regulating adipocyte differentiation. Methods: Porcine GOT1 knockout and overexpression vectors were constructed and transfected into the mouse adipogenic 3T3-L1 cells. Lipid droplets levels were measured after 8 days of differentiation. The mechanisms through which GOT1 participated in lipid deposition were examined by measuring the expression of malate dehydrogenase 1 (MDH1) and malic enzyme (ME1) and the cellular nicotinamide adenine dinucleotide phosphate (NADPH) content. Results: GOT1 knockout significantly decreased lipid deposition in the 3T3-L1 cells (p< 0.01), whereas GOT1 overexpression significantly increased lipid accumulation (p<0.01). At the same time, GOT1 knockout significantly decreased the NADPH content and the expression of MDH1 and ME1 in the 3T3-L1 cells. Overexpression of GOT1 significantly increased the NADPH content and the expression of MDH1 and ME1, suggesting that GOT1 regulated adipocyte differentiation by altering the NADPH content. Conclusion: The results preliminarily revealed the effector mechanisms of GOT1 in regulating adipose differentiation. Thus, a theoretical basis is provided for improving the quality of pork and studies on diseases associated with lipid metabolism. Objective: This study was performed to examine whether the porcine glutamic-oxaloacetic transaminase 1 (GOT1) gene has important functions in regulating adipocyte differentiation.Methods: Porcine GOT1 knockout and overexpression vectors were constructed and transfected into the mouse adipogenic 3T3-L1 cells. Lipid droplets levels were measured after 8 days of differentiation. The mechanisms through which GOT1 participated in lipid deposition were examined by measuring the expression of malate dehydrogenase 1 (MDH1) and malic enzyme (ME1) and the cellular nicotinamide adenine dinucleotide phosphate (NADPH) content.Results: GOT1 knockout significantly decreased lipid deposition in the 3T3-L1 cells (p<0.01), whereas GOT1 overexpression significantly increased lipid accumulation (p<0.01). At the same time, GOT1 knockout significantly decreased the NADPH content and the expression of MDH1 and ME1 in the 3T3-L1 cells. Overexpression of GOT1 significantly increased the NADPH content and the expression of MDH1 and ME1, suggesting that GOT1 regulated adipocyte differentiation by altering the NADPH content.Conclusion: The results preliminarily revealed the effector mechanisms of GOT1 in regulating adipose differentiation. Thus, a theoretical basis is provided for improving the quality of pork and studies on diseases associated with lipid metabolism.

Modulating charge transport characteristics of bis-azaisoindigo-based D-A conjugated polymers through energy level regulation and side chain optimization

Huang, Kaiqiang,Zhao, Xue,Du, Yuchang,Kim, Sanghyo,Wang, Xiaohong,Lu, Hongbo,Cho, Kilwon,Zhang, Guobing,Qiu, Longzhen The Royal Society of Chemistry 2019 Journal of Materials Chemistry C Vol.7 No.25

<P>Six donor-acceptor (D-A) conjugated polymers, P1-P6, based on the novel electron acceptors bis-isoindigo (BIID) and bis-azaisoindigo (BAID), were designed and synthesized for solution-processed organic field-effect transistors with high-performance optical and electrical properties. Energy level regulation was achieved by incorporation of nitrogen and fluorine heteroatoms and side chain optimization to reduce side chain density and extend branching point positions. Both the hole (<I>μ</I>h) and electron mobilities (<I>μ</I>e) significantly increased from P1 to P6, and there was an obvious transition from hole-dominated ambipolar charge transport behavior to highly-balanced ambipolar behavior. Since aza-substitution strengthened the electron-deficient property of the acceptor units, the entire molecular skeleton of BAID-based polymers has a high electron affinity and a low-lying lowest unoccupied molecular orbital (LUMO) level according to ultraviolet photoelectron spectroscopy (UPS) and cyclic voltammetry (CV) measurements. The <I>μ</I>e of BAID-based polymers is an order of magnitude higher than that of BIID-based polymers. In addition, side chain optimization was shown to significantly influence intermolecular interactions and supramolecular self-assembly. The stepwise reduction of the π-π stacking distances of P1-P6 calculated by GIXRD curves supports this conclusion. Finally, in P6 (PBAID3-2FBT), a maximum absorption wavelength (<I>λ</I>max) was observed at 797 nm, a low optical band gap (<I>E</I>g) of 1.27 eV, a low LUMO level of −3.90 eV, and an average <I>μ</I>h and <I>μ</I>e of 1.31 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>. This paper offers an available molecular design strategy to achieve highly-balanced and high-performance ambipolar charge carrier transport D-A conjugated polymers.</P>