IPOS three-state boost converter and its volt-second balance method based output voltage sharing control strategy for bipolar DC bus applications

Chen, Zhangyong,Feng, Chenchen,Chen, Gen,Chen, Yong,Zhu, Xintong The Korean Institute of Power Electronics 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.9

The bipolar DC bus configuration has been widely used in DC nano-grids due to its flexibility and stability. Input-parallel-output-series (IPOS) converters are utilized in bipolar DC bus and RES applications due to their simple structure. However, there is a big challenge with this structure. To ensure system safety and stability, the two output voltages of an IPOS converter need to be balanced. On this basis, an IPOS three-state boost converter with a balanced output voltage is proposed in this paper. At the same time, output voltage balance can be obtained by adjusting the duration of the three-state converter based on the volt-second balance method. In the proposed strategy, a switch series diode is added to the IPOS Boost converter topology, and the voltage across the main inductor can be changed through one degree of freedom, where the corresponding output voltage is regulated due to a change in inductor voltage. In addition, under different dead time conditions, adjusting the gate drive of the switch can be used to achieve voltage balance. Moreover, a comprehensive analysis and relative calculations are provided. Finally, a 20-200 V prototype is built to verify the analysis.

A GFP-labeled Human Colon Cancer Metastasis Model Featuring Surgical Orthotopic Implantation

Chen, Hong-Jin,Yang, Bo-Lin,Chen, Yu-Gen,Lin, Qiu,Zhang, Shu-Peng,Gu, Yun-Fei Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9

Colorectal cancer has become a major disease threatening human health. To establish animal models that exhibit the characteristics of human colorectal cancer will not only help to study the mechanisms underlying the genesis and development effectively, but also provide ideal carriers for the screening of medicines and examining their therapeutic effects. In this study, we established a stable, colon cancer nude mouse model highly expressing green fluorescent protein (GFP) for spontaneous metastasis after surgical orthotopic implantation (SOI). GFP-labeled colon cancer models for metastasis after SOI were successfully established in all of 15 nude mice and there were no surgery-related complications or deaths. In week 3, primary tumors expressing GFP were observed in all model animals under fluoroscopy and two metastatic tumors were monitored by fluorescent imaging at the same time. The tumor volumes progressively increased with time. Seven out of 15 tumor transplanted mice died and the major causes of death were intestinal obstruction and cachexia resulting from malignant tumor growth. Eight model animals survived at the end of the experiment, 6 of which had metastases (6 cases to mesenteric lymph nodes, 4 hepatic, 2 pancreatic and 1 mediastinal lymph node). Our results indicate that our GFP-labeled colon cancer orthotopic transplantation model is useful with a high success rate; the transplanted tumors exhibit similar biological properties to human colorectal cancer, and can be used for real-time, in vivo, non-invasive and dynamic observation and analysis of the growth and metastasis of tumor cells.

Improved hybrid fixed-frequency modulation strategy for series resonant converters for wide range applications

Zhu, Xintong,Chen, Zhangyong,Chen, Yong,Chen, Gen,Feng, Chenchen The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.9

In recent years, resonant converters have been widely used in the fields of electric vehicles and renewable energy systems due to their excellent characteristics in terms of high energy density, high energy efficiency, wide output range, and wide ZVS range. Conventional resonant converters generally adopt pulse frequency modulation (PFM) in a wide range of output applications. This means the frequency varies over a wide range, which results in problems such as high switch loss, large noise, and high EMI. To solve this problem, this paper proposes a hybrid fixed-frequency modulation strategy applied to a wide range of outputs based on the series resonant converter, where asymmetrical voltage-cancellation control (AVC control) and its improved strategy (IAVC control) are applied in the normalized gain ranges of [0.5, 1] and [0, 0.5]. The proposed modulation strategy achieves lower switching loss, higher efficiency, and better ZVS characteristics in wide voltage output and load ranges. Under the same output voltage and power, to realize ZVS, the proposed hybrid modulation has a smaller switching frequency and resonant current, which improves efficiency and reduce losses, especially in the case of low voltage gain and light load conditions. Finally, experimental data obtained from an 80 V input and a 800 W power max prototype circuit are included to verify the proposed hybrid modulation strategy.

Long Noncoding RNA Signature and Disease Outcome in Estrogen Receptor- Positive Breast Cancer Patients Treated with Tamoxifen

Gen Wang,Xiaosong Chen,Yue Liang,Wei Wang,Yan Fang,Kunwei Shen 한국유방암학회 2018 Journal of breast cancer Vol.21 No.3

Purpose: Recent data have shown that the expression levels of long noncoding RNAs (lncRNAs) are associated with tamoxifen sensitivity in estrogen receptor (ER)-positive breast cancer. Herein, we constructed an lncRNA-based model to predict disease outcomes of ER-positive breast cancer patients treated with tamoxifen. Methods: LncRNA expression information was acquired from Gene Expression Omnibus by re-mapping pre-existing microarrays of patients with ER-positive breast cancer treated with tamoxifen. The distant metastasis-free survival (DMFS) predictive signature was subsequently built based on a Cox proportional hazard regression model in discover cohort patients, which was further evaluated in another independent validation dataset. Results: Six lncRNAs were found to be associated with DMFS in the discover cohort, which were used to construct a tamoxifen efficacy-related lncRNA signature (TLS). There were 133 and 362 patients with TLS high- and low-risk signatures in the discover cohort. Both univariate and multivariate analysis demonstrated that TLS was associated with DMFS. TLS high-risk patients had worse outcomes than low-risk patients, with a hazard ratio of 4.04 (95% confidence interval, 2.83–5.77; p<0.001). Both subgroup analysis and receiver operating characteristic analysis indicated that TLS performed better in lymph node-negative, luminal B, 21-gene recurrence score high-risk, and 70-gene prognosis signature high-risk patients. Moreover, in a comparison of the 21-gene recurrence score and 70-gene prognosis signature, TLS showed a similar area under receiver operating characteristic curve in all patients. Gene Set Enrichment Analysis indicated that TLS high-risk patients showed different gene expression patterns related to the cell cycle and nucleotide metabolism from those of low-risk patients. Conclusion: This six-lncRNA signature was associated with disease outcome in ER-positive breast cancer patients treated with tamoxifen, which is comparable to previous messenger RNA signatures and requires further clinical evaluation.

Prospective Comparison of Redo Microvascular Decompression and Percutaneous Balloon Compression as Primary Surgery for Recurrent Trigeminal Neuralgia

Chen, Jing-nan,Yu, Wen-hua,Du, Hang-gen,Jiang, Li,Dong, Xiao-qiao,Cao, Jie The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.6

Objective : To prospectively compare facial pain outcomes for patients having either a repeat microvascular decompression (MVD) or percutaneous balloon compression (PBC) as their surgery for trigeminal neuralgia (TN) recurrence. Methods : Prospective cohort study of 110 patients with TN recurrence who had either redo MVD (n=68) or PBC (n=42) from July 2010 until September 2016. The mean follow-up was 45.6 months. Results : After redo MVD, 65 patients (95.6%) experienced immediate relief of pain. After PBC, 34 patients (81%) were immediately relieved of their neuralgia. After 1 month, the clinical effect of redo MVD was better than PBC (p<0.01). Patients who had redo MVD more commonly were pain free off medications (93.4% at 1 year, 78.2% at 4 years) compared with the PBC patients (85.1% at 1 year, 59.3% at 4 years). However, mean length of stay was longer (p>0.05). Patients after PBC who occurred developed herpes simplex (35.7%), facial numbness (76.2%), and annoying dysesthesia (21.4%) more frequently compared with patients after redo MVD who occurred developed herpes simplex (14.7%), facial numbness (8.8%), and hypoesthesia (5.9%) (p<0.05). The symptoms recurred respectively in 15 patients (22.1%) and 19 patients (45.2%) after redo MVD and PBC within the entire 6-year follow-up period. Conclusion : For the patients with TN recurrence, redo MVD was a more effective procedure than PBC. The cure rate and immediate relief of pain were better, and the incidence of complications was lower.

Formula for the Total Stopping Power from 2 keV to 10 keV for a Metal

Ai-Gen Xie,Min Lai,Chen-Yi Zhang 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.1

On the basis of the range-energy relationship, the relationships (L₂₋₁₀) among the total stopping power from 2 keV to 10 keV for a metal (S₂₋₁₀), the energy exponent (n₂₋₁₀), the primary energy at the surface (W_p0), and the parameter (A₂₋₁₀) were deduced. In addition, the relationships (L₁₀₋₃₀) among the total stopping power from 10 keV to 30 keV for a metal (S₁₀₋₃₀), the energy exponent (n₁₀₋₃₀), Wp0 and the parameter (A₁₀₋₃₀) were obtained. According to some relationships between the parameters of the secondary electron yield from 2 keV to 10 keV for a metal (δ₂₋₁₀), the composition of the secondary electron yield from 10 keV to 30 keV for a metal (δ₁₀₋₃₀), L₂₋₁₀, and L₁₀₋₃₀, the universal formula for expressing S₂₋₁₀ as a function of S₁₀₋₃₀, δ₂₋₁₀, δ₁₀₋₃₀, the backscattered coefficient (η) from 2 keV to 10 keV, η from 10 keV to 30 keV and Wp₀ was deduced. The S₂₋₁₀ calculated from this universal formula and the S₂₋₁₀ measured experimentally were compared, and we conclude that the formula presented in this paper is universal for S₂₋₁₀.

Safety Assessment of Ovarian Cryopreservation and Transplantation in Nude Mice Bearing Human Epithelial Ovarian Cancer

Zhu, Gen-Hai,Wang, Sheng-Tan,Yang, Zhao-Xin,Cai, Jun-Hong,Chen, Chun-Ying,Yao, Mao-Zhong,Hong, Lan,He, Guo-Li,Yang, Shu-Ying Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9

Objective: Nude mice with orthotopic transplantation of human ovarian epithelial cancer were used to investigate screening criteria for paraneoplastic normal ovarian tissue and the security of the freezing and thawing for ovarian tissue transplantation. Methods: Expression of CK-7, CA125, P53, survivin, MMP-2/TIMP-2 in paraneoplastic normal ovarian tissues were detected by RT-PCR as well as immunohistochemistry. The tissues of the groups with all negative indicators of RT-PCR, all negative indicators of immunohistochemistry, negative expression of CK-7, CA125 and survivin, positive expression of CK-7, CA125 and survivin, cancer tissues and normal ovarian tissues of nude mice were used for freezing and thawing transplantation, to analyze overt and occult carcinogenesis rates after transplantation. Results: When all indicators or the main indicators, CK-7, CA125 and survivin, were negative, tumorigenesis did not occur after transplantation. In addition the occult carcinogenesis rate was lower than in the group with positive expression of CK-7, CA125 and survivin (P<0.01). After subcutaneous and orthotopic transplantation of ovarian tissues, rates did not change (P>0.05). There was no statistical significance among rates after transplantation of ovarian tissues which were obtained under different severity conditions (P>0.05). Conclusion: Negative expression of CK-7, CA125 and survivin can be treated as screening criteria for security of ovarian tissues for transplantation. Immunohistochemical methods can be used as the primary detection approach. Both subcutaneous and orthotopic transplantation are safe. The initial severity does not affect the carcinogenesis rate after tissue transplantation. Freezing and thawing ovarian tissue transplantation in nude mice with human epithelial ovarian carcinoma is feasible and safe.

Feedback control of thermal frequency drift for a normal conducting cyclotron under CW operation

Chao Chujie,Chen Gen,Mao Yuzhou,Chen Yonghua,Zhang Xin 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.7

A normal conducting cyclotron is developed for medical purposes, which consists of the magnet, RF cavity, ion source, vacuum system, cooling system and control system. Especially, the RF cavity, which establishes an electric feld to accelerate charged particles, is one of the most critical and complex components in an cyclotron. During long-term continuous wave (CW) operation of the cavity, there will be a rise in temperature in the RF cavity due to its own thermal loss. This can lead to mechanical deformation and frequency deviation of the cavity, and thereby having a negative impact on its performance. That is, it will increase the refected power, lower the beam current, and cause instability in the cyclotron's operation. Therefore, based on the results of multi-physics analysis, which indicated that the frequency deviation is caused by thermal loss, an automatic frequency feedback control system was designed. In addition, a CW(25 kW) operation was tested, the results displayed that the maximum refected power decreased from 729 to 70 W, and the maximum detuning phase decreased from 12.26° to 1.9° by applying the feedback control system. The frequency of the cavity shifted approximately −22.8 kHz. The experimental results demonstrate that the frequency feedback control system is efective in compensating for frequency deviation caused by thermal loss.

Design and performance of the digital LLRF control system for isotope production cyclotron

Chao Chujie,Chen Gen,Mao Yuzhou,Chen Yonghua,Ding Kaizhong,Zhang Xin 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.2

The project of a 14 MeV cyclotron used for isotope production was developed by ASIPP (Hefei, China). To generate stable radionuclides by the cyclotron, the beam parameters should be stabilized rigorously. Therefore, a digital low-level RF system (LLRF) was designed and built to stabilize acceleration voltage and control the resonance of the cyclotron. The system can be confgured to use Non-IQ sampling techniques, resulting in a high performance RF control without the need of very high speed acquisition hardware. In this paper, the functional requirements of LLRF systems are analyzed, including the two feedback control loops, contain tuning loop, the amplitude loop, and the automatic conditioning process. Meanwhile, the hardware design of the FPGA-based core processing board is presented. In experiments, the automatic conditioning process was tested, which certifes the process can greatly shorten the conditioning time. The stability of the cavity voltage and control efect for the resonant frequency has also been measured, and the results show that the amplitude stability is better than 0.0092% under beam loading operation. Experimental results in diferent operating modes prove that the digital LLRF system can meet the demands of RF control systems for isotope production cyclotron.

A Study on Multi-Objective Fuzzy Optimum Design of Truss Structures

Mu, Zai-Gen,Ge, Xin,Yan, Mou,Chen, Yun-Zhou 한국공간구조학회 2003 한국공간구조학회지 Vol.3 No.2

This paper presents decision making method of structural multi-objective fuzzy optimum problem. The data and behavior of many engineering systems are not know precisely and the designer is required to design the system in the presence of fuzziness in the multi-goals, constraints and consequences of possible actions. In this paper, in order to find a satisfactory solution, the membership functions are constructed for the fuzzy objectives subject to the fuzzy constraints, and two approaches are presented by using the different types of fuzzy decision making. Thus, multi-objective fuzzy optimum problem can be converted into single objective non-fuzzy optimum problem and satisfactory solution of the multi-objective fuzzy optimum problem can be found with general optimum programming. Illustrative numerical example of the ten bar truss for minimum weight and minimum deflection is provided to demonstrate the process of finding the solution and the results are discussed.