137 results on '"Mi Yan"'
Search Results
2. The Policy-Making of Evacuation Route Based on Neural Network for Cruise Ship
- Author
-
Siyuan Shen, Dun Meng, and Mi Yan
- Published
- 2021
3. Timing Strategy for Active Detection of APT Attack Based on FlipIt Model and Q-learning Method
- Author
-
Liu, Zhilin, primary, Zhang, Hengwei, additional, Sun, Pengyu, additional, Mi, Yan, additional, Zhang, Xiaoning, additional, and Wang, Jindong, additional
- Published
- 2021
- Full Text
- View/download PDF
4. A Selection Strategy for Network Security Defense Based on a Time Game Model
- Author
-
Sun, Pengyu, primary, Zhang, Hengwei, additional, Ma, Junqiang, additional, Li, Chenwei, additional, Mi, Yan, additional, and Wang, Jindong, additional
- Published
- 2021
- Full Text
- View/download PDF
5. Study on Combustion Flow-Field of Solid Ducted Rocket with Multiple Gas Nozzles
- Author
-
Xiang Tang, Bo Zhang, Mi Yan, Xiaotao Tian, Zhao Wang, Junyi Chen, and Meng Huang
- Subjects
Shock wave ,Materials science ,business.product_category ,Rocket ,Airflow ,Nozzle ,Combustor ,Oblique shock ,Supersonic speed ,Mechanics ,Combustion ,business - Abstract
In order to gain the combustion flow characteristics in the secondary combustor and direct-connect inlet of the solid ducted rocket with multiple gas nozzles, the flow field parameters distribution and combustion performance of the engine under cold flow and combustion conditions were studied by experimental and numerical simulation methods. The results show that under the cold flow state, the supersonic airflow enters the secondary combustor at the high subsonic state after compressing by the oblique shock, which enhances the mixing effect of the secondary combustor. After the fuel-rich gas enters the secondary combustor through the multi-nozzles, the flow field structure becomes extremely complex, and multiple vortex recirculation zones are formed in the head area of the combustor. The distribution of the fuel-rich gas in the secondary combustor is more uniform, and the residence time of the gas and air increases, which enhances the effect of mixing and combustion organization, and the engine has better combustion performance. With the increase of fuel-rich gas flow, the pressure of the secondary combustor rises, and the oblique shock waves of pre-combustion moves forward continuously. The experimental and simulation results accurately capture the forwarding process and stable position of the oblique shock waves, which provides guidance for the subsequent design optimization of the solid ducted rocket.
- Published
- 2021
6. Roles of Physiological and Nonphysiological Information in Sun-Induced Chlorophyll Fluorescence Variations for Detecting Cotton Verticillium Wilt
- Author
-
Junru Zhou, Changping Huang, Yaohui Gui, Mi Yang, Ze Zhang, Wenjiang Huang, Lifu Zhang, and Qingxi Tong
- Subjects
Cotton verticillium wilt (VW) ,nonphysiological ,photosynthesis ,sun-induced chlorophyll fluorescence (SIF) ,Ocean engineering ,TC1501-1800 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
Sun-induced chlorophyll fluorescence (SIF) has been a promising indicator of plants’ physiological status, but its response to physiological changes under the verticillium wilt (VW) stress of cotton plants is complicated by concurrent nonphysiological changes. The relative contributions of the above two components to SIF variations are unclear at different VW stress severities, hindering the accurate diagnosis of VW levels. Therefore, the objective of this study is to investigate the dynamic responses of SIF, physiological and nonphysiological factors, and to evaluate the contributions of the two factors to SIF variations under different VW stress degrees of cotton. We continuously observed the diurnal variation of the top-of-canopy reflectance and SIF on healthy and VW-infected cotton during the peak incidence period of VW disease. To accurately quantify the relative contribution of each component to SIF, we proposed a practical strategy to estimate unmeasurable parameter when using Lindeman, Merenda, and Gold method. The results demonstrated the dominant role of physiological factors in SIF with an arch diurnal change pattern at the early stages of VW development. As the VW severity increased, the contribution of physiological components declined, with the maximum contribution decreasing by 47.7%, and the diurnal pattern was disrupted, with the diurnal variation amplitude of the parameter declining by 63.4%, followed by a shift in the regulatory role toward nonphysiological factors. This study contributes to a further understanding of the roles of physiological and nonphysiological components in SIF variations of cotton under VW stress, thus advancing the accurate monitoring of VW stress severity.
- Published
- 2024
- Full Text
- View/download PDF
7. Risk Evaluation on Ship Navigation System Based on Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation Method
- Author
-
Huajun Zhang, Lishou Liu, and Mi Yan
- Subjects
Computer science ,Evaluation methods ,Navigation system ,Analytic hierarchy process ,Data mining ,computer.software_genre ,computer ,Fuzzy logic ,Risk evaluation - Published
- 2021
8. Decision-making optimization method for submarine attack conditions
- Author
-
Mi Yan, Yuanbao Chen, Huajun Zhang, and Shuang Huang
- Subjects
Mathematical optimization ,Index system ,Computer science ,Component (UML) ,Simulated annealing ,Effective method ,Submarine ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Fuzzy logic ,Membership function ,Optimal decision - Abstract
As a strategic weapon with strong attack and high concealment, submarine's optimal operational maneuver decision is very important. However, the attack condition model of submarine can not be expressed directly by mathematical formula. This paper presents a method based on fuzzy comprehensive evaluation and multi-objective optimization to obtain the optimal decision of submarine. Firstly, according to FCE, the fuzzy evaluation index system of submarine attack condition is established, and each influencing factor is given a reasonable weight. After the weight of target layer is calculated by membership function, the attack condition of submarine is scored. In addition, this paper also uses simulated annealing algorithm to get the optimal decision of submarine attack condition, so as to get the corresponding subsystem input instructions under the optimal decision. The final simulation results show that this method is an effective method to obtain the optimal decision of submarine attack condition.
- Published
- 2021
9. High-Frequency Bipolar Solid-State LTD Based on a Self-Triggering H-Bridge.
- Author
-
Mi, Yan, Xu, Ning, Chen, Jiacheng, and Li, Zhengmin
- Subjects
- *
MAGNETIC cores , *ELECTROMAGNETIC fields , *MODULAR design , *ELECTRIC fields , *PULSE generators , *CAPACITOR switching - Abstract
In pulsed electromagnetic field tumor ablation, a bipolar nanosecond pulsed electric field has obvious therapeutic advantages. This article proposes a bipolar linear transformer drive (LTD) source circuit topology with a self-triggering H-bridge for this application. In this topology, in the absence of a magnetic core reset circuit, high-frequency bipolar pulse output is realized by introducing an H-bridge while keeping the circuit structure simple. A self-triggered H-bridge is formed by cleverly introducing a self-triggered circuit in the H-bridge, which reduces the difficulty of circuit control. There are only two main control signals, and the sources of all the main control switches share the same ground. The self-triggered switches are self-triggered through the energy-taking capacitor, which improves the stability of the switch control. Theoretical analysis and simulation results demonstrated the theoretical feasibility of the above-mentioned topology; thus, an experimental prototype was built to test the key parameters. The entire prototype adopts a modular design, and each module consists of only four self-triggering H-bridges and one nanocrystalline magnetic core. The key parameters of the final designed prototype are as follows: voltage amplitude of ±4 kV, pulse width of 60–260 ns, pulse rising edge of approximately 11 ns, continuous operation at a maximum frequency of 10 kHz, and output of 500 kHz high-frequency nanosecond pulse. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
10. Boosting Black-box Adversarial Attack with a Better Convergence
- Author
-
Yin, Heng, primary, Wang, Jindong, additional, Mi, Yan, additional, and Zhang, Xiaoning, additional
- Published
- 2020
- Full Text
- View/download PDF
11. Enhanced coercivity of Nd-Ce-Y-Fe-B sintered magnets by adding (Pr, Nd)-H powders
- Author
-
Mi Yan, Yang Liu, Jiaying Jin, and Baixing Peng
- Subjects
Materials science ,Remanence ,Phase (matter) ,Magnet ,Analytical chemistry ,Sintering ,Grain boundary ,Coercivity ,Magnetocrystalline anisotropy ,Temperature coefficient - Abstract
Incorporating cheaper and more abundant rare earth (RE) elements Ce, La or Y into the Nd-Fe-B based magnets has stimulated considerable research efforts [1], [2]. Among them, one promising candidate is the Y/Ce co-substituted Nd-Ce-Y-Fe-B sintered magnet, for which the Y-rich 2:14:1 phase with positive temperature coefficient of magnetocrystalline anisotropy can improve the thermal stability of magnetic properties. However, the inferior anisotropic field $(H_{A})$ of Ce 2 Fe 14 B and Y 2 Fe 14 B to Nd 2 Fe 14 B leads to low coercivity of the Nd-Ce-Y-Fe-B magnets when Y/Ce substitution for Pr/Nd exceeds 25 wt%. To further enhance the coercivity, in this work, ($\Pr _{20}$ Nd 80 )- H x powders were introduced into the (Nd,$\Pr) _{22.8}(\mathrm {Y}$,Ce) 7.7 Fe $_{bal} \mathrm {B}_{1}$ sintered magnets. Fig. 1 shows the room temperature coercivity $H_{cj}$ and remanence $B_{r}$ for the starting Y/Ce co-substituted magnet and the magnets added with 1, 2 and 3 wt% (Pr, Nd)-H powders, respectively. The coercivity can be effectively enhanced with the increase of (Pr, Nd)-H powders amount, for example, $H_{cj}$ is 10.3 kOe when added with 3 wt% (Pr, Nd)-H, which is 10.8% higher than that for the starting magnet. The coercivity increment is accompanied with very slight reduction in $B_{r}$ and $(BH ) _{max}$. After (Pr, Nd)-H powders is added, the intergranular RE-rich phase becomes clearer and more continuous when compared to the starting magnet, isolating well the adjacent grains. As shown in Fig. 2, the grain boundary layer is $\sim 10$ nm, which may play an important role to decouple the adjacent 2:14:1 phase grains during magnetization reversal. Meanwhile, the dehydrogenation of (Pr, Nd)-H during sintering promotes the diffusion of Nd and Pr towards the 2:14:1 phase grains. The formation of (Nd, Pr)-rich shell with locally enhanced magnetocrystalline anisotropy also contributes to the coercivity enhancement.
- Published
- 2018
12. Electro-Thermal Aging Law of Epoxy Resin under Bipolar Exponential Decay Pulse Voltage
- Author
-
Mi, Yan, primary, Deng, Shengchu, additional, Gui, Lu, additional, Liu, Lulu, additional, and Ouyang, Wenmin, additional
- Published
- 2018
- Full Text
- View/download PDF
13. Development of bipolar nano/microsecond pulse generator
- Author
-
Ke, Qiang, primary, Li, Chengxiang, additional, Yao, Cheng, additional, Du, Jian, additional, Yao, Chenguo, additional, and Mi, Yan, additional
- Published
- 2018
- Full Text
- View/download PDF
14. Dose response of muscle contraction of rabbit in vivo induced by high frequency nanosecond pulse bursts
- Author
-
Xu, Jin, primary, Mi, Yan, additional, Tang, Xuefeng, additional, Yang, Qiyu, additional, Liu, Hongliang, additional, and Tang, Junying, additional
- Published
- 2017
- Full Text
- View/download PDF
15. Electrothermal aging characteristics of epoxy resin under bipolar exponential decay pulse voltage and its insulation life evaluation based on Cole-Cole model.
- Author
-
Mi, Yan, Liu, Lulu, Deng, Shengchu, Gui, Lu, and Ouyang, Wenmin
- Subjects
- *
EPOXY resins , *ELECTRIC potential , *DIELECTRIC relaxation , *HIGH voltages , *EXPONENTIAL functions , *DIELECTRIC properties - Abstract
The epoxy resin insulation in saturable reactors in a HVDC transmission converter valve is subjected to a bipolar exponential decay pulse voltages under normal operating conditions and its aging mechanism is still unclear. In this paper, an electrothermal aging experiment of epoxy resin was carried out under bipolar exponential decay pulse voltages at high temperature. The dielectric properties of epoxy resin before and after aging were measured using frequency-domain spectroscopy. To quantitatively study the aging characteristics, the double-relaxation Cole-Cole model was used to fit the dielectric spectra. As a result, an exponential function relationship between the relaxation time constant and the aging time of epoxy resin under various aging conditions was obtained. This relationship can be used as an empirical formula to evaluate the degree of aging. Furthermore, a comparison of the aging life characteristics of epoxy resin under pulse and sinusoidal voltages with the same peak value was performed. The results show that the electrothermal aging rate of epoxy resin under a pulse voltage is lower than under a sinusoidal voltage. The effect of the measurement temperature on the insulation life evaluation of epoxy resin was also analyzed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
16. Comparison of Bipolar and Unipolar Pulses in Cell Electrofusion: Simulation and Experimental Research.
- Author
-
Li, Chengxiang, Ke, Qiang, Yao, Cheng, Yao, Chenguo, Mi, Yan, Wu, Meng, and Ge, Liangpeng
- Subjects
ELECTROFUSION ,CELL fusion ,BIPOLAR cells ,BIOELECTROCHEMISTRY ,CELL death - Abstract
Objective: Unipolar pulses have been used in cell electrofusion over the last decades. However, the problem of high mortality with unipolar pulses has not been solved effectively. The cell fusion rate is restricted by cell mortality. By using the advantages of bipolar pulses which cause less cell damage, this paper attempts to use bipolar pulses to increase the cell fusion rate. Methods: the transmembrane voltage and pore density of cells subjected to unipolar/bipolar pulses were simulated in COMSOL software. In an experiment, two 40 μs unipolar and two 20–20 μs bipolar pulses with electric fields of 2, 2.5, and 3 kV/cm were applied to SP2/0 murine myeloma cells. To determine the cell fusion rate and cell mortality, cells were stained with Hoechst 33342 and propidium iodide. Results: the simulation in this paper showed that a high transmembrane voltage and a high pores density were concentrated only at the contact area of cells when bipolar pulses were used. The results of the cell staining experiment verified the simulation analysis. When bipolar pulses were applied, the cell mortality was significantly reduced. In addition, the cell fusion rate with bipolar pulses was almost two times higher than that with unipolar pulses. Conclusion: for cell electrofusion, compared with unipolar pulses, bipolar pulses can not only reduce the cell mortality remarkably but also improve the cell fusion rate obviously. Significance: this paper introduces a novel way to increase the fusion rate of cells. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
17. An MMC-based modular unipolar/bipolar high-voltage nanosecond pulse generator with adjustable rise/fall time.
- Author
-
Mi, Yan, Wan, Hui, Bian, Changhao, Peng, Wencheng, and Gui, Lu
- Subjects
- *
HIGH voltages , *PULSE generators , *CONVERTERS (Electronics) , *METAL oxide semiconductor field-effect transistors , *ELECTRIC switchgear , *ELECTRIC discharges - Abstract
The rise/fall time of a high-voltage nanosecond pulse affects the application effect of the pulse; therefore, it is of great significance to study the adjustment of the rise/fall time. In this paper, a new type of generator topology based on a half-bridge modular multilevel converter (HB-MMC) is proposed that uses MOSFETs as solid-state switches to produce a unipolar/bipolar high-voltage nanosecond pulse with an adjustable rise/fall time. The proposed topology consists of 2 arms, each of which contains several HB-MMC submodules. The capacitors of each arm are charged with a positive voltage and negative voltage in parallel. By controlling the discharging sequence of the two arms, a unipolar or bipolar pulse can be generated. For each arm, by setting the switching sequence of the MOSFETs, the number of capacitors inserted into the discharging circuit can be controlled to allow a multilevel pulse to be generated. The rise/fall time of the output pulse can be adjusted by changing the number of levels and the duration of each level. Detailed illustrations of the proposed configuration and its operational concept are presented. Experimental results for a scaled-down prototype are presented to validate the concept. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
18. Electroporation modeling of a single cell exposed to high-frequency nanosecond pulse bursts.
- Author
-
Mi, Yan, Xu, Jin, Yao, Chenguo, Li, Chengxiang, and Liu, Hongliang
- Subjects
- *
ELECTROPORATION , *ORGANELLES , *CELL membranes , *SIMULATION methods & models - Abstract
This paper considers the electroporation characteristics of a cell under high-frequency nanosecond pulse bursts. A typical two-dimensional cell system, including an organelle membrane, was discretized into nodes using MATLAB, and the mesh transport network method model was established after the bidirectional coupling properties of electrical transport and pore transport were assigned to the nodes within this model. The dynamic process in single-cell electroporation under the application of 10 unipolar high-frequency nanosecond pulse bursts at 1 Hz to the target system was simulated and analyzed. The electroporation characteristics of a single pulse burst and multiple pulse bursts were evaluated. Particularly, the effect of intra-burst frequency on the average pore radius was examined. For the plasma membrane, when multiple pulses were applied, the pore number remained unchanged while the pore radius at the transition region exhibited a more obvious cumulative effect at higher intra-burst frequencies. For the organelle membrane, the number of pores significantly increased when the intra-burst frequency was high (1 MHz). Repetitive pulse bursts expanded the pore radius but do not change the pore number. The results of the present study further enrich our understanding of the electroporation mechanism of a pulsed electric field acting on biological cells. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
19. Multiparametric Finite-Element Simulation and Experiment on Thermal Effects in Skin Tumor Exposed to High-Frequency Nanosecond Pulse Bursts.
- Author
-
Mi, Yan, Peng, Wencheng, Rui, Shaoqin, Bian, Changhao, Tang, Xuefeng, Xu, Jin, Kuang, Dongdong, and Luo, Qing
- Subjects
- *
ELECTRIC fields , *TUMOR treatment , *TISSUES , *MELANOMA , *SKIN tumors - Abstract
This paper introduces unipolar high-frequency nanosecond pulse bursts, which combine the advantages of microsecond pulsed electric fields and nanosecond pulsed electric fields, for the treatment of tumors. To take full advantage of this nonthermal pulsed electric field treatment, it is necessary to study the thermal effects of the high-electric-field nanosecond pulse bursts inside tumor tissue. A multiparametric analysis is performed based on a finite-element model of skin with a melanoma tumor that is nipped using the Tweezertrodes. The electric field ranges from 1 to 10 kV/cm, the pulsewidth ranges from 50 to 500 ns, and the frequency in the pulse bursts ranges between 100 kHz and 1 MHz. The total pulselength is $100~\mu \text{s}$ , and the frequency of the pulse bursts is 1 Hz. The Pennes bioheat transfer equation and the Arrhenius equation are used to calculate the temperature and the thermal damage. For pulse parameters of 5 kV/cm, 500 ns, and 1 MHz, the simulated temperature of the skin tumor is only 37.48 °C after 1 s, and the thermal damage is negligible. The temperature and thermal damage to the melanoma tumor in the skin are simulated and calculated for various electric fields, pulse widths, and frequencies. The relationship between the thermal effects on the tumor and the pulse parameters is researched, and pulse parameters for a tumor without thermal damage are ascertained. Temperature measurements of melanoma tumors in nude mice in vivo show that the change in experimental temperature in the tumors is consistent with the simulated average tumor temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
20. A Modular Generator of Nanosecond Pulses With Adjustable Polarity and High Repetition Rate.
- Author
-
Mi, Yan, Bian, Changhao, Li, Pan, Yao, Chenguo, and Li, Chengxiang
- Subjects
- *
ELECTRIC lines , *PULSE generators , *LASER pulses , *ELECTRIC transformers , *SUPERPOSITION principle (Physics) - Abstract
High-repetition-rate nanosecond pulses are used widely in many fields, and pulses of different polarities have different effects. A new pulse-generator structure is proposed based on an improved Blumlein pulse-forming line (BPFL) and a transmission-line transformer (TLT). The proposed structure generates pulses with polarity that can be adjusted among positive, negative, and bipolar. A modular design is used for the generator. In each module, three groups of solid-state switches are used to control the BPFL. By adjusting the timing of the control signal, the BPFL can generate high-repetition-rate nanosecond primary pulses with adjustable polarity. These primary pulses are then transmitted to the load through the TLT with amplification and superposition. The pulse-forming process is analyzed theoretically for matched impedance. The strategy for controlling the switches is also illustrated. In addition, the feasibility of the proposed generator is verified by simulations and experiments. Finally, a four-stage prototype is developed that can produce pulses with amplitudes of 0–10 kV, a width of 30 ns, repetition rates up to 200 kHz and adjustable polarity. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
21. Design and Development of a Compact All-Solid-State High-Frequency Picosecond-Pulse Generator.
- Author
-
Li, Chengxiang, Wang, Enzhao, Tan, Jianwen, Zhang, Ruizhe, Wang, Shuhui, Yao, Chenguo, and Mi, Yan
- Subjects
PULSE generators ,SEMICONDUCTOR devices ,PICOSECOND pulses ,TRANSISTORS ,ELECTRIC circuits - Abstract
The Marx circuit structure based on fast high-power semiconductor devices is the classical way of generating picosecond pulses. However, most reported studies suggest that as the number of stages in the Marx circuit increases, the output pulse amplitude tends to saturate. This has of late made high-voltage picosecond-pulse generation a challenge. In this paper, as the number of stages increases, the internal resistance of the avalanche transistor tends to decrease with increasing current flowing through the avalanche transistor. A step-by-step wiring and debugging of the avalanche transistor-based Marx circuit demonstrates this experimentally. That is, for a certain range in the number of stages, saturation of the output pulse amplitude for the Marx circuit of avalanche transistors is not apparent. Introducing a parallel structure for the transistors not only increases the current level of the entire circuit but also further reduces the equivalent resistance of the avalanche transistors, thereby improving the output efficiency. Drawing on microstrip transmission theory, and combining the Marx circuit and avalanche transistor parallel structure, component parameters and circuit topology of the picosecond-pulse generator were redesigned, and a 30-level Marx circuit with a parallel structure of two avalanche transistors was developed. The picosecond-pulse generator outputs a pulse with adjustable voltage amplitude of 0.9–3.1 kV, a 350-ps full-width at half-maximum, a 150-ps rise time, and an adjustable high-stability repetition rate of up to 10 kHz. The number of pulses is precisely controlled. The generator is an all-solid-state compact device with high frequency suitable for research needs. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
22. Study of cell viability and thermal effects under high-frequency composite pulses
- Author
-
Zhao, Yajun, primary, Yao, Chenguo, additional, Mi, Yan, additional, Li, Chengxiang, additional, Dong, Shoulong, additional, Lv, Yanpeng, additional, Liu, Hongmei, additional, Tang, Liling, additional, He, Lin, additional, Wang, Xiaoyu, additional, and Chen, Ying, additional
- Published
- 2016
- Full Text
- View/download PDF
23. Design of bipolar pulse generator topology based on Marx supplied by double power
- Author
-
Dong, Shoulong, primary, Yao, Chenguo, additional, Mi, Yan, additional, Li, Chengxiang, additional, Zhao, Yajun, additional, Lv, Yanpeng, additional, and Liu, Hongmei, additional
- Published
- 2016
- Full Text
- View/download PDF
24. Design and fabrication of an uniform electric field producing microfluidic electroporation chip based on MEMS technology
- Author
-
Gong, Lingyu, primary, Yao, Chenguo, additional, Lv, Yanpeng, additional, Mi, Yan, additional, and Li, Chengxiang, additional
- Published
- 2016
- Full Text
- View/download PDF
25. Multi-parameter analysis in single-cell electroporation based on the finite element model
- Author
-
Liu, Hongmei, primary, Yao, Chenguo, additional, Mi, Yan, additional, Li, Chengxiang, additional, Zhao, Yajun, additional, and Lv, Yanpeng, additional
- Published
- 2016
- Full Text
- View/download PDF
26. A high repetition-rate bipolar submicrosecond pulse generator based on magnetic pulse compression system
- Author
-
Mi, Yan, primary, Wan, Jialun, additional, Bian, Changhao, additional, Peng, Wencheng, additional, Yao, Chenguo, additional, and Li, Chengxiang, additional
- Published
- 2016
- Full Text
- View/download PDF
27. Effect of Low-Field High-Frequency nsPEFs on the Biological Behaviors of Human A375 Melanoma Cells.
- Author
-
Zhang, Bingyu, Kuang, Dongdong, Tang, Xuefeng, Mi, Yan, Luo, Qing, and Song, Guanbin
- Subjects
MELANOMA ,ELECTRIC field therapy ,CANCER cell analysis ,CANCER cell proliferation ,APOPTOSIS ,FLOW cytometry - Abstract
Objective: To evaluate the effect of low-field high-frequency nanosecond pulsed electric fields (nsPEFs) on multiple biological behaviors of human A375 melanoma cells and to optimize suitable parameters for further study and clinical use. Methods: An nsPEF generator was developed to generate appropriate pulses. Cell apoptosis and the cell cycle were evaluated by flow cytometry. The CCK-8 assay was performed to explore the effect of nsPEFs on the viability of A375 melanoma cells. Cell migration was assessed using a Transwell Boyden Chamber. The proliferation of A375 melanoma cells was determined by the cloning efficacy test. Furthermore, the nude mouse tumorigenicity assay was used to detect the effectiveness of nsPEFs in vivo. Results: The nsPEFs with our tested parameters failed to induce apoptosis of A375 melanoma cells, though nsPEFs with high pulse duration (500 ns) induced necrosis. However, the viability and migration of A375 melanoma cells were significantly inhibited by nsPEFs. nsPEFs also suppressed the proliferation of A375 melanoma cells by restricting cells in G0/G1 phase. Moreover, animal experiments demonstrated that nsPEFs inhibited the growth of melanoma in vivo. Conclusion: Low-field high-frequency nsPEFs failed to induce apoptosis but effectively inhibited the growth of melanoma via affecting other biological behaviors of melanoma cells, such as cell viability, proliferation, and migration. Significance: This study investigated the influence of low-field high-frequency nsPEFs on melanoma through evaluating their effects on multiple biological behaviors and is helpful in the treatment of melanoma and other tumors. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
28. Simulation Study of an Impulse Radiation Antenna Array.
- Author
-
Li, Chengxiang, Zhao, Yuying, Du, Jian, Zhang, Yuanyuan, Mi, Yan, and Yao, Chenguo
- Subjects
SIMULATION methods & models ,IMPULSE (Physics) ,ANTENNA arrays ,ULTRA-wideband antennas ,NONINVASIVE ventilation ,PICOSECOND pulses - Abstract
A picosecond-pulse electric field, matching ultra-wideband antenna, can be applied to biomedical noninvasive therapy. Its effect depends largely on the electric field intensity on the target. Because the amplitude enhancement of a picosecond-pulse source is restricted by many factors, ultra-wideband time-domain antenna research has become important. Here, the intensity of the electromagnetic radiation propagated by the antenna was greatly improved by arraying the antenna feed structure. For targeted focusing, an ellipsoidal reflective surface is commonly utilized, but this structure limits the formation feasibility of the feed structure. Here, the feed structure and the reflector were arrayed at the same time, while satisfying the time and spatial consistency of the electromagnetic waves at the target, the intensity of the electric field at the target was greatly improved, and the size of the focal spot was reduced simultaneously. A Gaussian pulse with a 1-V amplitude and a 200-ps width was used as the excitation source. Using this antenna array, a focal spot less than $1\times 1\times 1$ cm was formed at the target. Also, with the increased number of elements in the antenna array, the electric field intensity of the target increased. The relationship between the field intensity at the target and the number of combined antennas is discussed. The increased field strength eventually levels off, which is also consistent with the theory. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
29. A High-Repetition-Rate Bipolar Nanosecond Pulse Generator for Dielectric Barrier Discharge Based on a Magnetic Pulse Compression System.
- Author
-
Mi, Yan, Wan, Jialun, Bian, Changhao, Zhang, Yanyuan, Yao, Chenguo, and Li, Chengxiang
- Subjects
- *
PULSE compression (Signal processing) , *VERY high frequencies , *MAGNETIC control , *PULSE generators ,MAGNETIC properties of dielectrics - Abstract
Magnetic pulse compression (MPC) systems are suitable for generating dielectric barrier discharges (DBDs) owing to their capability of producing high-amplitude, short pulse voltage waves. This paper proposes a high-frequency, bipolar magnetic compression system to study DBD plasma characteristics. First, the principle of bipolar MPC is explained [a bipolar MPC system comprises a full bridge inverter circuit, pulse transformer (PT), and magnetic switch (MS)]. Additionally, the design of the PT and MS is described. Then, the waveform of the resistive load is tested and compared with PSpice simulation results. It was found that the nanosecond pulse generator produces a pulse on a resistor with an amplitude of 0–13 kV, a rise time of approximately 100 ns, and a repetition frequency of 0 to several kHz. Finally, this paper studies the plasma characteristics under the application of a high-frequency bipolar pulse, and the charge–voltage Lissajous figure of the discharge waveform is analyzed. Combining discharge photographs and theoretical calculation results yields the relationship between the discharge characteristics and the frequency, which enriches the theoretical study of high-frequency bipolar discharges. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
30. Electroporation simulation of a multicellular system exposed to high-frequency 500 ns pulsed electric fields.
- Author
-
Mi, Yan, Xu, Jin, Tang, Xuefeng, Yao, Chenguo, and Li, Chengxiang
- Subjects
- *
ELECTRIC fields , *TUMOR treatment , *BIOPHYSICS , *COAGULATION , *ELECTROPORATION - Abstract
Nanosecond pulsed electric fields (nsPEFs) with higher repetition frequency presents potential better clinic applicability for tumor treatment. However, the biophysical mechanisms of high-frequency multi-pulse protocols are currently unclear. In this study, a multicellular model with scale of 131 × 121 μm was used to evaluate the accumulation of pore number and pore radius with increasing numbers of pulses. This multicellular system was established based on the transport lattice model combined with the Smoluchowski equation (SE) electroporation model and solved using Pspice and Matlab. The transient and spatial responses of the system under 10 unipolar high-frequency 500 ns pulses with different field intensities (3 kV/cm, 5 kV/cm and 10 kV/cm) and different frequencies (100 kHz, 500 kHz and 1 MHz) were then analyzed. The results show that with increasing numbers of pulses, the pore number remained basically the same but its value was larger when a higher intensity field was applied. The pore evolutions were similar at different field intensities. However, pulse frequency had a significant influence on the changes of pore radius. Pore radius growth effects were more obvious with higher frequency because of its shorter pulse intervals. The results presented here provide theoretical support for mechanism of tumor treatment with high-frequency nanosecond pulses. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
31. Comparative Study of the Biological Responses to Conventional Pulse and High-Frequency Monopolar Pulse Bursts.
- Author
-
Yao, Chenguo, Zhao, Yajun, Mi, Yan, Dong, Shoulong, Lv, Yanpeng, Liu, Hongmei, Wang, Xiaoyu, and Tang, Liling
- Subjects
ELECTROPORATION ,THERMOLYSIS ,PHOSPHATIDYLSERINES ,CELL death ,ELECTRIC field effects ,PLASMA temperature - Abstract
Given its nonthermal property and other advantages, irreversible electroporation (IRE) has quickly translated into clinical applications. An increasing number of clinical cases using IRE have also revealed crucial issues. The uneven distribution of the electric field caused by the heterogeneity of biological tissues has not been completely and effectively addressed to date. The use of high-frequency monopolar pulse bursts (HFMPBs) is expected to solve this problem. The high-frequency content of the HFMPB is used to ensure the uniform distribution of the electric field in the tissue. A temperature increase similar to that of the conventional pulse method does not cause thermal damage and results in a killing effect similar to that of the conventional technique. Meanwhile, the subpulse has a pulse duration of 1– 100~\mu \texts , which remains unexplored and may induce new cell responses. This paper analyzes the HFMPB based on the frequency domain and infers that the cell death pathways under this pulse induce necrosis and other processes, such as apoptosis. The phosphatidylserine externalization rate had a peak value at a different inner frequency of HFMPB when the electric field was 1 kV/cm for melanoma cells. This new type of pulse is expected to solve the problem of the uneven distribution of the electric field without altering the cell killing effect. If this effect is also verified in tissue ablation, these new types of pulses will promote the clinical application of IRE. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
32. Performance evaluation of RSSI-based transmitter identification using USRP
- Author
-
Mi Yan, Shan Kang, Xiaoxiao Chen, and Naiwen Chen
- Subjects
Emulation ,Engineering ,business.industry ,Universal Software Radio Peripheral ,Reliability (computer networking) ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Transmitter ,Real-time computing ,Physical layer ,Identification (information) ,Cognitive radio ,Radio frequency ,business ,Computer network - Abstract
Primary User Emulation (PUE) attack is one of the most common attack in the physical layer of the Cognitive Radio Networks (CRN). In order to defense PUE attack, we propose a transmitter identified method based on RSSI of vary frequency to indentify transmitters located in different positions. We use Universal Software Radio Peripheral (USRP) as the transmitter and receiver to verify our method in an indoor environment. Experiment results show that our method can identify transmitters with different locations reliably.
- Published
- 2011
33. Performance analysis of Channel-based FingerPrint using NS2 simulator
- Author
-
Xiaoxiao Chen, Wenbin Lin, Lianfen Huang, Liang Xiao, and Mi Yan
- Subjects
Engineering ,Spoofing attack ,Wireless network ,Property (programming) ,business.industry ,Transmitter ,Data_CODINGANDINFORMATIONTHEORY ,Transmission (telecommunications) ,Fingerprint ,Electronic engineering ,business ,Decorrelation ,Computer Science::Information Theory ,Communication channel - Abstract
In this paper, we investigate the performance of a Channel-based FingerPrint (CFP) algorithm incorporated with the conventional higher-layer security mechanism to counteract spoofing in wireless networks. This algorithm utilizes the channel estimation results of the receiver to discriminate among different transmitters, based on the rapid decorrelation property of channel responses. Compared to the previous work, we consider multiple complicated communication scenarios, where the receiver applies CFP to discriminate among multiple transmitters in various transmission patterns in practical network settings. Simulation results provide the required signal-to-noise-ratio (SNR) by this algorithm and show the impact of the test threshold and the transmission pattern.
- Published
- 2011
34. Detecting identity-spoof attack based on BP network in cognitive radio network
- Author
-
Shan Kang, Xiaoxiao Chen, Mi Yan, and Naiwen Chen
- Subjects
Engineering ,Spoofing attack ,Exploit ,business.industry ,MAC address ,RSS ,Transmitter ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,computer.file_format ,Constant false alarm rate ,Cognitive radio ,business ,computer ,Radio broadcasting ,Computer network - Abstract
In the cognitive radio network (CRN), all the cognitive user opportunistic access the spectrum, so it can improve the spectrum utilization. As a smart spectrum sharing technology, cognitive radio can change its transmitter parameter based on interactive the environment where it operates. So the MAC address can be easy spoofed in the open air. An attacker can exploit this character to preempt spectrum resources and bring the negative impact to the network. In this paper, we propose a scheme of detecting identity-spoof attack based on Back Propagation (BP) network. The scheme extracts the fingerprint feature of cognitive user to get the received signal strength (RSS). The extracted Eigen values can be used as the input vectors of the BP neural network which are trained by the honest users' RSS. The honest users and the attackers can be divided into two categories by the trained BP network to detect an identity-spoof attack. Simulation result shows that our scheme can effectively detect identity-spoof attack with a low false alarm rate and miss alarm rate.
- Published
- 2011
35. Game-Theoretic Approach against Selfish Attacks in Cognitive Radio Networks
- Author
-
Jianbin Tang, Lianfen Huang, Liang Du, Liang Xiao, and Mi Yan
- Subjects
business.industry ,Network security ,Computer science ,TheoryofComputation_GENERAL ,Throughput ,Computer security ,computer.software_genre ,symbols.namesake ,Cognitive radio ,Nash equilibrium ,symbols ,Repeated game ,Network performance ,Communications protocol ,business ,Game theory ,computer ,Computer network - Abstract
Cognitive Radio (CR) networks are vulnerable to selfish attacks, where secondary users increase their accessing probability to enhance their own utilities, resulting in serious performance degradation in CR networks. Therefore, we formulate the secure access for CR networks into a static game called Back off Window Control Game (BWCG) and a repeated game with punishment mechanism based on the CSMA protocol. We have proven the existence of a Nash Equilibrium in the BWCG game and design a punishment mechanism to motivate selfish users not to perform selfish attacks in the repeated game. Simulation results show that the proposed scheme can improve the network performance and the punishment mechanism can efficiently prevent selfish attacks in CR networks.
- Published
- 2011
36. Electronics Properties of Single-Walled Twisted Carbon Nanotubes
- Author
-
Zhi-shun Chen, Li-guang Wang, Da-peng Hao, Qing-fang Fu, Terence K.S. W, Xiao-mi Yan, and Dao-wei He
- Subjects
Materials science ,Condensed matter physics ,Band gap ,Fermi level ,Non-equilibrium thermodynamics ,Electronic structure ,Carbon nanotube ,law.invention ,symbols.namesake ,Zigzag ,law ,symbols ,Density functional theory ,Electronic band structure - Abstract
Electronic properties are calculated and simulited by using density functional theory based on the nonequilibrium Green's function when a zigzag single-wall carbon nanotube (SCNTs) is twisted. We found that the twist of the single-wall carbon nanotube decreases their transmission function in certain energy ranges but some peaks are higher than unit despite twisting strongly affects the electronic structure of SCNT. The transmission peaks reduces gradually with twisting angle increasing. In addition, SCNT develops a Fermi-level which initially scales linearly with twisting angle and then reaches a constant value, the energy band gaps decrease with the twisting angles. All results indicate that SCNTs have lower electronic transport performance when the twisting angle increases, especially for large twisting angles.
- Published
- 2011
37. On Selfish Behavior in Wireless Sensor Networks: A Game Theoretic Case Study
- Author
-
Liang Xiao, Lianfen Huang, Liang Du, and Mi Yan
- Subjects
Optimization problem ,business.industry ,Computer science ,Distributed computing ,Throughput ,symbols.namesake ,Nash equilibrium ,Distributed algorithm ,Media access control ,symbols ,Repeated game ,business ,Game theory ,Wireless sensor network ,Computer network - Abstract
In this paper, we study the selfish behavior in wireless sensor networks and apply a game theory method to address this problem in a CSMA/CA protocol. More specifically, we formulate the Media Access Control (MAC) layer activity in sensor networks as an optimization problem in terms of the random accessing problem. Then we propose a distributed algorithm for the system to reach the Nash Equilibrium (NE). We have de-fined a Contention Window Select Game (CWSG) in which each sensor selects its own contention window to control the access probability. This approach can improve the average performance, compared to a random strategy with each sensor selecting its own window independently. We prove the unique existence of NE in the CWSG, and propose a penalizing mechan-ism based on repeated game to prevent the non-cooperative selfish behavior of decreasing the contention window without per-mission.
- Published
- 2011
38. Experimental study on the killing effect of the irreversible electroporation in different frequencies
- Author
-
Zhao, Yajun, primary, Yao, Chenguo, additional, Mi, Yan, additional, Dong, Shoulong, additional, and Liu, Hongmei, additional
- Published
- 2015
- Full Text
- View/download PDF
39. Study on temperature of liver and tumor under high frequency nanosecond pulsed field
- Author
-
Rui, Shaoqin, primary, Mi, Yan, additional, Liu, Lian, additional, Yao, Chenguo, additional, and Li, Chengxiang, additional
- Published
- 2015
- Full Text
- View/download PDF
40. Simulation studies on the impact of the firing of action potential of myocytes with bipolar pulses
- Author
-
Zhang, Ruizhe, primary, Li, Chengxiang, additional, Yao, Chenguo, additional, and Mi, Yan, additional
- Published
- 2015
- Full Text
- View/download PDF
41. The optimal Design of Electrod Array using Electroporation Based on the Finite Element
- Author
-
Li Chengxiang, Zhao Dong-yang, Yao Chenguo, and Mi Yan
- Subjects
Optimal design ,Materials science ,business.industry ,Electric field ,Electrode ,Electrode array ,Optoelectronics ,Distribution uniformity ,business ,Finite element method ,Voltage ,Biomedical engineering ,Power (physics) - Abstract
With the promotion of the electroporation therapy clinical application, how to design an electrode with a lower voltage level and distribution and high intensity electric field in order to achieve the optimal treatment of tumors. In this paper, FEMLAB finite element analysis software is used for the needle electrodes in biological tissue electroporation for electric field simulation, the simulation results show that: voltage amplitude, the distance between positive and negative electrode needle, needle electrodes and the number of needle electrodes, and other distribution methods will affect the effective electric field area of biological tissue. By comparing different needle electrodes corresponds to the structure of the electric field distribution uniformity, the effective electric field (Eeff) radius of coverage as well as the size of the rated output voltage power supply requirements, We has designed optimal structure of the needle electrodes (seven plum blossom-shaped electrodes acupuncture), which provide a theoretical basis for the production of needle electrodes.
- Published
- 2008
42. A Review on Molecular Dynamics Simulation for Biological Effects of Pulsed Electric Field
- Author
-
Wang Jianfei, Li Chengxiang, Mi Yan, and Yao Chenguo
- Subjects
Molecular dynamics ,Nanostructured materials ,Electric field ,Nanotechnology ,Electric pulse ,Nanosecond ,Biological effect ,Engineering physics - Abstract
In recent years, the electric field in the application of biological research has become a hot spot, However, the mechanism still lags behind the experimental study. Molecular dynamics simulation could not only get the atomic trajectory, but also get a variety of observation like to do the same experiment. Therefore we could choose molecular dynamics simulation to study the mechanism. This article discusses the basic principles of the molecular dynamics simulation; comprehensive analysis research status and recent applications of molecular dynamics simulation in electric field biological effect at home and abroad. In particular, we have a detailed description and analysis of the biological effects of pulsed electric field of molecular dynamics simulation results, such as nanopore formation at membranes in response to a high-intensity (~0.5 V/nm), nanosecond electric pulse. And On this basis, the development trends and application prospects of molecular dynamics simulation on pulsed electric field in the biological effects is put forward.
- Published
- 2008
43. Programmable voltage regulating method for high voltage DC power supply based on digital potentiometer and linear photoelectric coupling
- Author
-
Du Lin, Li Chengxiang, Yao Chenguo, Mi Yan, Chen Xin, and Wang Shi-shou
- Subjects
Engineering ,Low-dropout regulator ,Switched-mode power supply ,business.industry ,Voltage divider ,Electronic engineering ,Electrical engineering ,High voltage ,Voltage regulation ,Voltage optimisation ,Switched-mode power supply applications ,business ,Digital potentiometer - Abstract
In order to solve the disadvantages caused by mechanical slide rheostat that they were big errors and low precision, a novel voltage regulation method for high voltage DC power supply was introduced. The key of this method were digital potentiometer Maxim 5455 and linear photoelectric coupling LOC110, and application programs were compiled using Visual Basic which was graphical compiling language, furthermore the communication between exterior and computer was carried out by ICP7044D module, in consequence the output value of high voltage DC power supply could be regulated with computer. The measured results showed that this method could accurately, conveniently and rapidly regulate the output value of high voltage DC power supply.
- Published
- 2008
44. Simulation and Calculation of Electric Field Power on Plasma Membrane Exposed to Steep Pulsed Electric Field
- Author
-
Mi Yan, Li Chengxiang, Luo Xiao, and Yao Chenguo
- Subjects
Cell membrane ,Electromagnetic field ,Nuclear magnetic resonance ,medicine.anatomical_structure ,Membrane ,Materials science ,Electric field ,Traction (engineering) ,medicine ,Perpendicular ,Mechanics ,Dielectric ,Plasma - Abstract
The basic characteristic of the electric field is that it has a powerful function on the materials put in it. Under this power, both within and outside the cell membrane and its surface have a strong electric field distribution, at the same time, due to the difference among the dielectric constant of the cell membrane and the extracellular fluid and the cytoplasm, there must be a force acts on the cell surface depending on the electromagnetic field theory. In order to a further exposition of the irreversible breakdown mechanism on the steep pulsed electric field to the malignant cells, this article using the MATLAB takes the malignant tumor cells and the normal cells as the objects of study respectively, on the theory calculates and simulates the forces suffered by the cells separately under the steep pulsed electric field, and gives the results of a comparative analysis. This study finds that there is a cross traction along the membrane plane in addition to the compression strength perpendicular to the surface of it. The lateral force will reduce the tension of the film significantly, leading to electroporation and rupture on the cell membrane. The tensity changing quantity that the same electric field (6.7times107 V/m) produces in normal cells is 2 m Nm-1, while in tumour cells it is 10 m Nm-1. It can be seen that the strength towards the malignant tumor cells is 1 magnitude bigger than that towards the normal cells.
- Published
- 2008
45. Analysis on Mobile E-Commerce Value-Chain
- Author
-
Mi Yan
- Subjects
Software ,Risk analysis (engineering) ,business.industry ,Computer science ,Value (economics) ,Mobile computing ,Mobile business development ,E-commerce ,Construct (python library) ,Mobile telephony ,Marketing ,business ,SWOT analysis - Abstract
This paper introduces the content, characteristics and current situation of mobile e-commerce, and points out that building the mobile e-commerce value chain is a practical problem in the development of mobile e-commerce. Using Porterpsilas value-chain theory, it tries to construct a mobile e-commerce value-chain. Then through analyzing the value-chain by SWOT, we can find the strategy of mobile e-commercepsilas development, which would benefit the economic development greatly.
- Published
- 2008
46. ExactMP: An Efficient Parallel Exact Solver for Phylogenetic Tree Reconstruction Using Maximum Parsimony
- Author
-
Vaddadi P. Chandu, David A. Bader, and Mi Yan
- Subjects
Theoretical computer science ,Speedup ,Branch and bound ,Parallel processing (DSP implementation) ,Phylogenetic tree ,Heuristic (computer science) ,Heuristic ,Computer science ,Tree rearrangement ,Solver ,Genome ,Algorithm ,Maximum parsimony - Abstract
Constructing phylogenetic trees in the study of the evolutionary history of a group organisms is an extremely challenging problem in computational biology. The problem becomes intractable with growing number of organisms. In this paper, we design and implement an efficient parallel solver (ExactMP) using a parsimony based approach for solving this problem. We create a testbed consisting of eighteen datasets of varying size (up to 27 taxa) and difficulty level (easy to hard), containing real (Eukaryotes, Metazoan, and rbcL) and randomly-generated synthetic genome sequences. We demonstrate our ExactMP Solver against this testbed and achieve a parallel speedup of up to 7.26 with 8 processors using an 8-way symmetric multiprocessor. The main contributions of this work are: (1) an efficient parallel solver ExactMP for the problem of phylogenetic tree reconstruction using maximum parsimony, (2) a new upper bounding methodology for this problem using heuristic and randomization techniques, and (3) a highly optimized branch and bound algorithm for this problem.
- Published
- 2006
47. Ontology Modeling for Contract: Using OWL to Express Semantic Relations
- Author
-
Yalan Yan, Mi Yan, and Jinlong Zhang
- Subjects
Ontology Inference Layer ,Knowledge management ,Computer science ,computer.internet_protocol ,business.industry ,Process ontology ,Ontology-based data integration ,Suggested Upper Merged Ontology ,Ontology (information science) ,OWL-S ,World Wide Web ,Upper ontology ,business ,computer ,Ontology alignment - Abstract
There exist the generic concepts and semantic relationships in the description of procedural knowledge and strategic knowledge in contract management. In order that contract information could be understood and processed by machine automatically, more semantic descriptions are needed. Ontology has become a promising technology to express semantics. At present, Web ontology languages have been standardized. However, building domain ontology based on OWL (Ontology Web Language) just begins and has a long way to go. In building domain ontology, people should explore the rationality in expressing domain concepts and relations between the concepts, considering the capabilities of OWL (not the capability of natural languages). In this paper, we put forward a framework of contract ontology after considering capabilities to express semantic relations provided by OWL. Then we use Prot?g?-2000 to build OWL representations of the contract ontology and make some analyses. Our exploration might not standardize contract ontology. We explore with the intention to help people better understand the rationality in expressing concepts and relations between the concepts in contract management in order that OWL contract ontology and other domain ontology are improved and standardized as soon as possible.
- Published
- 2006
48. A modular solid-state nanosecond pulsed generator based on Blumlein-line and transmission line transformer with microstrip line.
- Author
-
Mi, Yan, Bian, Changhao, Wan, Jialun, Xu, Jin, Yao, Chenguo, and Li, Chengxiang
- Subjects
- *
PULSE frequency modulation , *PULSE circuits , *MICROSTRIP transmission lines , *ELECTRIC lines , *ELECTRIC impedance - Abstract
A high pulse repetition frequency (PRF) nanosecond pulse generator based on Blumlein pulse forming line (BPFL) and transmission line transformer (TLT) is proposed in this paper. The generator combines the BPFL characteristic, which is used to generate a narrow, high PRF pulse, with the excellent performance at high frequency of a transmission line transformer. A modular structure was adopted for this design. The primary pulse produced by the BPFL in each module will output to the load through the TLT amplifier; further, the output of multiple modules can be cascaded to improve the load voltage and output power. Moreover, this reduces the ratio of the output impedance and the input impedance of the TLT, making the generator more suitable for light loads. A microstrip line was used for the transmission line, which makes it possible to match random loads. Additionally, the size of generator was greatly reduced to realize a compact design. MOSFETs were used in the generator to facilitate the control of both the amplitude and PRF of the output. A two-stage laboratory prototype was fabricated to verify the performance of the proposed topology. As a result, the generator produced pulses for matched loads with amplitudes of 0?2.5 kV, pulse width of 20 ns, and repetition frequencies of 0?10 kHz. The generator can be used as a hardware foundation for research on the biomedical effects of exposure to high PRF nanosecond pulse electric fields. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
49. Compact solid-state Marx-bank sub-nanosecond pulse generator based on gradient transmission line theory.
- Author
-
Li, Chengxiang, Wang, Enzhao, Yao, Chenguo, Mi, Yan, Tan, Jianwen, and Zhang, Ruizhe
- Subjects
PULSE generators ,ELECTRIC lines ,ELECTRIC impedance ,IMPEDANCE matching ,TRANSISTORS - Abstract
For non-invasive treatments in the biomedical field, sub-nanosecond pulse electric field matching ultra-wideband antennas have aroused great interest for their excellent directivity and targeted treatment. Sub-nanosecond pulse generators have proved difficult to control in pulsed power technologies despite many studies of pulse generators based on avalanche transistor theory and the Marx circuit. However, no solution exists to the problems of non-ideal waveform of the output sub-nanosecond pulse and the relatively low effectiveness of the Marx circuit. To resolve these problems, the paper describes a sub-nanosecond pulse generator simulation model based on gradient transmission line theory in PSPICE simulation software and the development of a compact solid-state sub-nanosecond pulse generator (18 cm?18 cm?4 cm). From experimental tests, trigger signals of 5-V amplitude, 5-ns rise and fall times (pulse-width 10 ns-50 ns) were generated by Field-Programmable Gate Array (FPGA). A pulse with 1600-V voltage amplitude, 300-ps full width at half maximum, 150-ps rise time, and 10-kHz high-stability repetition rate was generated in an attenuator load with high-bandwidth (8 GHz, 50 ?). The effectiveness (Output pulse voltage amplitude / Charge voltage ? Stages) of this Marx circuit reached to 41.7%, improving considerably on previous efforts. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
50. Analysis of Dynamic Processes in Single-Cell Electroporation and Their Effects on Parameter Selection Based on the Finite-Element Model.
- Author
-
Yao, Chenguo, Liu, Hongmei, Zhao, Yajun, Mi, Yan, Dong, Shoulong, and Lv, Yanpeng
- Subjects
ELECTROPORATION ,FINITE element method ,ELECTRIC fields ,MEDICINE ,ELECTRIC conductivity - Abstract
Pulsed electric fields have recently been the focus of considerable attention because of their potential application in biomedicine. However, their practical clinical applications are limited by poor understanding of the interaction mechanism between pulsed electric fields and cells, particularly in the process of electroporation and its effect on parameter selection. This paper established a multishelled dielectric model based on finite elements to simulate and analyze the processes involved in electroporation. In particular, the processes include the dynamic development of the pore radius and electroporation region: the distribution of recoverable, nonrecoverable, and nonelectroporation areas on the cell; and the influence of pulse parameters on varying degrees of electroporation. Results showed that membrane conductivity, pore density, transmembrane potential, and distribution of pore radii are functions of time and position on the cell. The electroporation areas were divided into recoverable, nonrecoverable, and no-electroporation pores. For 10~\mu \texts , 1.5-kV/cm pulse was observed in the regions exposed to sufficiently high transmembrane voltage (1 V), electroporation occurred, membrane conductivity and pore density (up to 10^\mathrm 16/\textm^\mathrm 2) rapidly increased with time, and electroporation areas increased gradually and were mainly distributed in the range 0°–70° (recoverable pore [0°, 35°], nonrecoverable pore [35°, 70°], and no-electroporation pore [70°, 90°]). Electric field strength was the major factor that induced electroporation, particularly in the recoverable pore, but it had minimal effect on pore expansion. However, pulse duration affects the nonrecoverable pore, such that the high-intensity wide pulse is more useful in the field of irreversible electroporation. The high-intensity short pulse can increase permeability and maintain cell viability. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.