Research on Output Characteristics of Double-Ended Fixed Beam Piezoelectric Energy Harvester Under Random Excitation

Lian-min Cao,Yong Cai,Guotai Xu,Jiulong Cui 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.6

By use of the concept of impedance, this paper establishes a random energy harvester output model of double-ended fi xed beam piezoelectric energy harvester under random White Gaussian noise excitation, which is based on the discussion of the output characteristics infl uenced by changing vibration beam shape and piezoelectric sheet length under random excitation, while improving piezoelectric structure of double-ended fi xed beam piezoelectric energy harvester. It also deduces the output voltage, current and power of energy harvester with Fokker–Planck equation, which are verifi ed by Monte Carlo simulation and experimental testing. It can be found that improving vibration beam shape can reduce resonant frequency and increase average output power of the system. The optimal value of piezoelectric sheet length can be diff erent corresponding to diff erent structures, which proves that double-ended fi xed beam piezoelectric energy harvester under random White Gaussian noise excitation can achieve maximum output with optimal piezoelectric sheet length. In addition, in order to further improve the output performance of piezoelectric energy harvester under random excitation, it is necessary to increase the acceleration spectral density under random excitation and set an optimal value of the piezoelectric loading resistance, which is more suitable for energy harvester applied under random low-frequency environment.

A Study on the Simulation Model of the Surface Roughness for Turning Process

Min-Sung Hong(홍민성),Zhe-Man Lian(염철만),Jong-Min Kim(김종민) 한국생산제조학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.10

Design and Test of the MEMS Coupled Piezoelectric- Electromagnetic Energy Harvester

Lian-min Cao,Zhi-xu Li,Cheng Guo,Peng-peng Li,Xiang-qiang Meng,Ting-ming Wang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.4

This paper researches on the design and test of the output performance of double-end clamped MEMS coupled piezoelectric–electromagnetic energy harvester. It establishes the theoretical output model of the double-end clamped rectangular beam and trapezoidal beam piezoelectric–electromagnetic energy harvester, and optimizes the structure parameters of piezoelectric and electromagnetic unit with simulation analysis. It also respectively realizes the processing of piezoelectric and electromagnetic unit by MEMS and flexible PCB technology, and completes the performance test of structure prototype through the experimental system. The result showed that the capacity of MEMS coupled piezoelectric–electromagnetic energy harvester, which taked four coil piezoelectric with integrated electromagnetic in series, was 12.23 times higher than that of piezoelectric energy harvester. Also the output voltage and power of coupled trapezoidal beam energy harvester were respectively increased 18.89% and 2.26%, compared with coupled rectangular beam energy harvester.

Research on an Anchor Point Lever Beam Coupling Type Tuning Fork Micro-gyroscope

Lian-min Cao,Jian-wei Li,Xian-wen Liu,Feng-yao Sun 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.6

This paper has designed an anchor point lever beam coupled tuning fork micro-gyroscope and tested its output performance. The tuning fork micro-gyro is designed to eliminate the output error caused by orthogonal coupling and in-phase-inverting coupling by structural decoupling and electrical decoupling, and can improve the anti-vibration performance and the modal optimization ability. It has derived the dynamic response working model of the non-ideal tuning fork micro-gyroscope, and optimized the structural parameters of the micro-gyroscope by simulation analysis. The microstructure processing has been realized by the SOI-MEMS process, sealed the processed structural prototype, and tested the performance through the established experimental system. According to the test results, the designed micro-gyroscope driving direction has greatly reduced the in-phase-inverting coupling through the anchor coupling lever beam, and the detection direction eff ectively suppressed the in-phase-inverting coupling through the stiff ness matching electrode. While closed-loop detecting, the measured Aallan variance zero-bias stability is 1.779°/h, and the 1σ zero-bias stability is 8.3°/h. While applying a stiff ness matching voltage, the measured vibration sensitivity is 23.9°/h/g.

A Study on the Simulation Model of the Surface Roughness for Turning Process

Hong, Min-Sung,Lian, Zhe-Man,Kim, Jong-Min 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-

In this paper, a surface generation model is presented to simulate surface roughness profile in turning operation. The simulation model takes into account the effect of tool geometry, process parameters, rotational errors of spindle, and the relative vibration between the cutting tool and workpiece. The surface roughness profiles are simulated based on the surface-shaping system. The model has been verified by comparing the experimental values with the simulation values. It is shown that the surface simulation model can properly predict the surface roughness profile.

Two New Species of The Genus Tmarus(Araneae, Thomisidae) from China

Yin Chang Min, Peng Xian-Jin, Gong Lian Su, 김주필(Joo Pil Kim) 한국거미연구소 2004 한국거미 Vol.20 No.1

게거미과의 중국산 신종인 Tmarus yani와 Tmarus gongi을 보고하고자 한다. The present paper deals with two new species, Tmarus yani sp. novo and Tmarus gongi sp. nov., from China. Type specimens are deposited at College of Life Sciences, Hunan Normal University. Measurements are in millimeter.

Downregulation of LINC01508 contributes to cisplatin resistance in ovarian cancer via the regulation of the Hippo-YAP pathway

Lan Xiao,Xiao-Yan Shi,Ze-Lian Li,Min Li,Min-Min Zhang,Shi-Jie Yan,Zhao-Lian Wei 대한부인종양학회 2021 Journal of Gynecologic Oncology Vol.32 No.5

Background: Some long non-coding RNAs (lncRNAs) have been found to contribute to cisplatin resistance. Here, we identified a novel lncRNA that was downregulated in cisplatin- resistant to ovarian cancer (OC) cells and aimed to examine the contribution of LINC01508 to cisplatin resistance in OC cells. Methods: Differences in the lncRNA expression profile between OV2008 and C13K cells were assessed by lncRNA expression microarray. The expression of LINC01508 in ovarian epithelial cells, four OC cells, and OC, benign ovary tumor and normal ovary, cisplatin- resistant and non-resistant OC specimens were evaluated by quantitative real-time polymerase chain reaction (qPCR). The role of LINC01508 in OC cisplatin-resistant was evaluated by cell counting kit-8 (CCK-8), flow cytometry, colony formation, wound healing, Transwell, and tumor growth inhibition study in vivo. The clinical associations of LINC01508 in OC were evaluated using correlation analysis. The effects of verteporfin (VP) on cisplatin were explored to reveal the function of the hippo-YAP pathway on the cisplatin tolerance of C13K. Results: LINC01508 was downregulated in cisplatin-resistant OC cells and platinum- resistant OC tissue (p<0.01). LINC01508 downregulation was correlated with tumor size, residual tumor, and platinum resistance. The overexpression of LINC01508 improves in vitro and in vivo sensitivity to cisplatin while predicts the poor overall survival which need further follow-up research. The increased level of LINC01508 could suppress the cisplatin resistance of OC cells through the inhibition of the hippo-YAP pathway. Conclusions: The study proposes that dysregulation of LINC01508 expression results in resistance of OC to cisplatin through the inhibition of the hippo-YAP pathway.

Neural Stem Cells Modified by a Hypoxia-Inducible VEGF Gene Expression System Improve Cell Viability under Hypoxic Conditions and Spinal Cord Injury

Lian Jin, Hong,Pennant, William A.,Hyung Lee, Min,Su, Sung,Ah Kim, Hyun,Lu Liu, Meng,Soo Oh, Jin,Cho, Joon,Nyun Kim, Keung,Heum Yoon, Do,Ha, Yoon Lippincott Williams Wilkins, Inc. 2011 1528-1159) Vol.36 No.11

STUDY DESIGN.: An in vitro neural hypoxia model and rat spinal cord injury (SCI) model were used to assess the regulation of therapeutic vascular endothelial growth factor (VEGF) gene expression in mouse neural stem cells (mNSCs) by the EPO (erythropoietin) enhancer or RTP801 promoter. OBJECTIVE.: To increase VEGF gene expression in mNSCs under hypoxic conditions in SCI lesions but avoid unwanted overexpression of VEGF in normal sites, we developed a hypoxia-inducible gene expression system consisting of the EPO enhancer and RTP801 promoter fused to VEGF or the luciferase gene, then transfected into mNSCs. SUMMARY OF BACKGROUND DATA.: On the basis of the ischemic response in the injured area, poor cell survival at the transplantation site is a consistent problem with NSC transplantation after SCI. Although VEGF directly protects neurons and enhances neurite outgrowth, uncontrolled overexpression of VEGF in uninjured tissue may cause serious adverse effects. To effectively improve NSC survival in ischemic sites after transplantation, we evaluated mNSCs modified by a hypoxia-inducible VEGF gene expression system in an SCI model. METHODS.: Hypoxia-inducible luciferase or VEGF plasmids were constructed using the EPO enhancer or RTP801 promoter. The effect of these systems on targeted gene expression and cell viability was evaluated in mNSCs in both hypoxic in vitro injury and a rat SCI model in vivo. RESULTS.: The gene expression system containing the EPO enhancer or RTP801 promoter significantly increased the expression of the luciferase reporter gene and therapeutic VEGF gene under hypoxic conditions. The Epo-SV-VEGF plasmid transfection group had significantly fewer apoptotic cells in vitro. This system also augmented cell viability in the in vivo SCI model. CONCLUSION.: These results strongly suggest the potential utility of mNSCs modified by a hypoxia-inducible VEGF gene expression system in the development of effective stem cell transplantation protocols in SCI.

A numerical study on the correlation between the evolution of propeller trailing vortex wake and skew of propellers

Lian-Zhou Wang,Chun-Yu Guo,Yu-Min Su,Tie-Cheng Wu 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

The characteristics of the relationship between the evolution of propeller trailing vortex wake and skew angle are numerically examined based on four different five-blade David Taylor Model Basin (DTMB) model propellers with different skew angles. Numerical simulations are based on Reynolds-averaged NaviereStokes (RANS) equations combined with SST k u turbulence model. Results show that the contraction of propeller trailing vortex wake can be restrained by increasing skew angle and loading conditions, and root vortices fade away when the propeller skew angle increases. With the increase of the propeller's skew angle, the deformation of the hub vortex and destabilization of the tip vortices are weakening gradually because the blade-to-blade interaction becomes weaker. The transition trailing vortex wake from stability to instability is restrained when the skew increases. Furthermore, analyses of tip vortice trajectories show that the increasing skew can reduce the difference in trailing vortex wake contraction under different loading conditions.

선삭에서 공구열변형이 표면 형상에 미치는 영향에 관한 연구

염철만,신근하,홍민성 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.4

During the turning of the workpiece, cutting heat causes thermal deformation of the cutting tool which influence the surface characteristics of the machined part. This paper presents a study of thermal deformation of the cutting tool. For this purpose, cutting tool is modeled based on Pro/Engineering and the thermal deformation is simulated by means of the finite element method. The thermal effect on the surface roughness profile is simulated by using surface-shaping system. It has been shown that the results of simulation are similar to those of experiment.