Thermal analysis for the large precision EDM machine tool considering the spark energy during long-time processing

Zhaoxi Zhao,Yukui Wang,Zhen-long Wang,Jianyong Liu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

Thermal error is a major factor influencing the accuracy of large precision electrical discharge machining (EDM) machine tools, especially when processing continuously for a long time. In this paper, a novel thermal analysis model was set up to identify the static and dynamic thermal behaviour of the large EDM machine tool. The thermal effect of multiple spark discharges is considered. An equivalent heat flux method was proposed to model the intermittent heat flux for the first time. Both the steady and transient analyses were applied to investigate the thermal equilibrium time of critical points. It is found that when the study point is far away from the heat source, the longer thermal equilibrium time is needed. And the thermal equilibrium time of the machine tool was also estimated. Verification experiment has been performed, indicating the simulation accuracy of 87 % on the temperature rise of the electrode. Moreover, on the displacement of the spindle, the simulated result matched with the experimental result in Z direction error of 7 %. Finally, suggestions for reducing the thermal deformation were proposed to further improve the machining accuracy of large EDM machine tools.

H₂O₂ Inhibits Proliferation and Mediates Suppression of Migration via DLC1/RhoA Signaling in Cancer Cells

Ma, Long,Zhu, Wen-Zhen,Liu, Ting-Ting,Fu, Hui-Ling,Liu, Zhao-Jun,Yang, Bing-Wu,Song, Tai-Yu,Li, Guo-Rong Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.4

Background: RhoGTPase-activating proteins (RhoGAPs) regulate RhoGTPases in cells, but whether individual reactive oxygen species (ROS) regulate RhoGAPs is unknown. Our previous published papers have shown that deleted in liver cancer 1 (DLC1) inhibits cancer cell migration by its RhoGAP activity. The present study was designed to explore the role of $H_2O_2$ in regulation of DLC1. Materials and Methods: We treated cells with $H_2O_2$ for 24h and phenotypic changes were analyzed by MTT, RT-PCR, Western blotting, immunofluorescence staining and wound healing assays. Results: $H_2O_2$ downregulated cyclin D1 and cyclin E to inhibit proliferation, and upregulated BAX to induce apoptosis in MCF-7 cells. Compared with non-tumorigenic cells, $H_2O_2$ increased expression of DLC1 and reduced activity of RhoA in cancer cells. Stress fiber production and migration were also suppressed by $H_2O_2$ in MDA-MB-231 cells. Conclusions: Our study suggests that $H_2O_2$ inhibits proliferation through modulation of cell cycle and apoptosis-related genes, and inhibits migration by decreasing stress fibers via DLC1/RhoA signaling.

Dynamic thermal behavior and thermal error prediction of spindle due to periodic jump motions in a large precision die-sinking EDM machine

Zhaoxi Zhao,Jia Zhang,Yukui Wang,Zhen-long Wang,Jianyong Liu,Chenghao Quan 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7

Thermal error which has been widely studied in cutting machine tools, was ignored in the EDM machines in most cases, since there is usually no high-speed rotation for spindles. However, for large die-sinking EDM machines, due to heavy load of drive system and long processing cycle of large aeronautical parts, thermal error induced by jump motion has seriously impaired the machining accuracy and gradually been recognized. In this paper, the dynamic thermal behavior of spindle induced by periodic jump motions in large precision die-sinking EDM machine was studied for the first time. Noted that the Z-axis base and column show obvious temperature rise and the thermal error in Y direction is the largest, which is about 6.5 and 5 times compared with that in X and Z directions. Based on this, an efficient thermal error prediction model was presented. Thermal sensitive points were picked out through fuzzy clustering and correlation theory, taken as inputs of radial basis function (RBF) neural network to guarantee the accuracy. As a result, the prediction accuracy in X, Y and Z directions are 95.2 %, 92.5 % and 94.4 %, respectively. Finally, the effect of jump period on spindle thermal behavior was investigated, and suggestions for optimizing jump motion parameters were proposed to further improve the machining accuracy of large EDM machines.

Overlapping Stents-Assisted Coiling for Vertebral Artery Dissecting Aneurysm : LVIS Stent within Neuroform EZ Stent

Liu, Xing-Long,Wang, Bin,Zhao, Lin-Bo,Jia, Zhen-Yu,Shi, Hai-Bin,Liu, Sheng The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.4

Objective : To evaluate the safety and efficacy of an overlapped stenting-assisted coiling technique in treating vertebral artery dissecting aneurysm (VADA) via Low-profile Visualized Intraluminal Support (LVIS) stent-within-Neuroform EZ stent. Methods : From January 2017 to June 2019, 18 consecutive patients with VADAs (ruptured : unruptured=5 : 13) were treated with the overlapping stents assisted-coiling technique in our center. The overlapping manner was a Neuroform EZ stent being deployed first, followed by LVIS stents placement using the 'shelf' technique. The patients' clinical characteristics, technical feasibility and safety, and immediate and follow-up angiographic results were retrospectively reviewed. Results : Seventeen (94.4%) procedures were technically successful with an exact deployment of the stents and patent parent or perforator arteries. The immediate angiographies after procedure confirmed Raymond class I, II, and III occlusion of VADAs were in 12 (66.7%), two (11.1%), and four cases (22.2%), respectively. Post-procedural complications developed in one patient (5.6%) with minor brainstem infarctions, which resulted from an in-stent thrombosis during the procedure. Angiographic follow-up at 5.7 months (range 3 to 9 months) demonstrated Raymond class I and II occlusion were in all cases (100%). The modified Rankin Scale scores at 21.3 months (range 15 to 42 months) 0-2 in 17 cases (94.4%) and three in one case (5.6%). Conclusion : Overlapping stents via LVIS stent-within-Neuroform EZ stent combined with coiling is safe and effective for patients with VADA in the midterm results.

Facile Fabrication of Quaternary Ammonium Salt Modified Cotton Linter by Radiation Grafting and its Effective Removal of Methyl Orange: Batch and Dynamic Flow Mode Studies

Jifu Du,Manman Zhang,Zhen Dong,Xin Yang,Houhua Xiong,Zhengkui Zeng,Zhiyuan Chen,Long Zhao 한국섬유공학회 2022 Fibers and polymers Vol.23 No.4

Methyl orange plays a vital role in various branches of the dyeing and textile industries and must be treated beforebeing discharged into the environment. In this study, methacryloxyethyltrimethyl ammonium chloride (DMC) functionalizedcotton linter (DMCCL) was prepared using a radiation technique. The prepared DMCCL was then characterized by IR, SEM,TG, and XPS analyses. The results showed that DMC was successfully grafted onto the surface of the cotton linter. Theadsorption performance toward methyl orange (MO) was investigated using batch and fix-bed column experiments. Adsorption kinetic and isotherm studies were well described by pseudo-second-order kinetic and Langmuir isotherm model,respectively. The maximum adsorption capacity for MO was 645.16 mg/g. The fixed-bed column experiment showed thatThomas and Yoon-Nelson models described the experimental data well. The column study showed the adsorption capacityreached 564.46 mg/g with a MO concentration of 25 mg/l and flow rate 1.5 ml/min. The saturated DMCCL column could beregenerated efficiently by eluting with 1 M HCl. Therefore, the DMCCL exhibited excellent adsorption performance, whichis suitable for MO removal from aqueous solution.

LCL Resonant Compensation of Movable ICPT Systems with a Multi-load

Jie Hua,Hui-Zhen Wang,Yao Zhao,Ai-Long Zou 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

Compared to LC resonance, LCL resonance has distinct advantages such as a large resonant capability, low voltage and current stresses of the power device, constant voltage or current output characteristics, and fault-tolerance capability. Thus, LCL resonant compensation is employed for a movable Inductive Contactless Power Transfer (ICPT) system with a multi-load in this paper, which achieves constant current output characteristics. Peculiarly, the primary side adopts a much larger compensation inductor than the primary leakage inductor to lower the reactive power, reduce the input current ripple, generate a large current in the primary side, and realize soft-switching. Furthermore, this paper proposes an approximate resonant point for large inductor-ratio LCL resonant compensation through fundamental wave analysis. In addition, the PWM control strategy is used for this system to achieve constant current output characteristics. Finally, an experimental platform is built, whose secondary E-Type coils can ride and move on a primary rail. Simulations and experiments are conducted to verify the effectiveness and accuracy of both the theory and the design method.

LCL Resonant Compensation of Movable ICPT Systems with a Multi-load

Hua, Jie,Wang, Hui-Zhen,Zhao, Yao,Zou, Ai-Long The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

Compared to LC resonance, LCL resonance has distinct advantages such as a large resonant capability, low voltage and current stresses of the power device, constant voltage or current output characteristics, and fault-tolerance capability. Thus, LCL resonant compensation is employed for a movable Inductive Contactless Power Transfer (ICPT) system with a multi-load in this paper, which achieves constant current output characteristics. Peculiarly, the primary side adopts a much larger compensation inductor than the primary leakage inductor to lower the reactive power, reduce the input current ripple, generate a large current in the primary side, and realize soft-switching. Furthermore, this paper proposes an approximate resonant point for large inductor-ratio LCL resonant compensation through fundamental wave analysis. In addition, the PWM control strategy is used for this system to achieve constant current output characteristics. Finally, an experimental platform is built, whose secondary E-Type coils can ride and move on a primary rail. Simulations and experiments are conducted to verify the effectiveness and accuracy of both the theory and the design method.

Clinical Study on Safety and Efficacy of Microwave Ablation for Primary Hyperparathyroidism

Ying Wei,Lili Peng,Yan Li,Zhen-long Zhao,Ming-an Yu 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.5

Objective: To evaluate the safety, feasibility, and efficacy of microwave ablation (MWA) for the treatment of primary hyperparathyroidism (PHPT). Materials and Methods: This study enrolled 67 PHPT patients (22 men, 45 women; mean age, 56.0 ± 16.3 years; range, 18– 83 years) from January 2015 to December 2018. The laboratory data, including the serum intact parathyroid hormone (iPTH), calcium, phosphorus, and alkaline phosphatase (ALP) levels, were evaluated before MWA and again 2 hours, 1 day, 7 days, 1 month, 3 months, 6 months, 12 months, 18 months, and 24 months after. Results: Complete ablation was achieved with all 72 hyperplastic parathyroid glands found on the 67 patients enrolled, 64 of whom were treated in one session and 3 were treated over two sessions. The technical success rate was 100%. The median follow-up time was 13.6 months (range, 10.0–31.1 months). The clinical success rate was 89.4%. The volume reduction rate was 79.4% at 6 months. Compared to pre-MWA, the serum iPTH, calcium, phosphorus, and ALP levels had significantly improved 6 months post-MWA (iPTH, 157.3 pg/mL vs. 39.2 pg/mL; calcium, 2.75 ± 0.25 mmol/L vs. 2.34 ± 0.15 mmol/L; phosphorus, 0.86 ± 0.20 mmol/L vs. 1.12 ± 0.22 mmol/L; ALP, 79 U/L vs. 54 U/L, respectively; all, p < 0.01). Hoarseness was a major complication in 4 patients (6.0%), but it improved spontaneously within 2–3 months. Conclusion: MWA is safe, feasible, and effective for the treatment of PHPT.