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- 저자 : J. Z. FENG (검색결과 29 건)
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R&D Status of High-current Accelerators at IFP
J. J. Deng,J. S. Shi,W. P. Xie,L. W. Zhang,K. Z. Zhang,S. P. Feng,J. Li,M. Wang,Y. He,L. S. Xia,Z. Y. Dai,H. T. Li,L. Wen,S. F. Chen,X. Li,Q. G. Lai,M. H. Xia,Y. C. Guan,S. Y. Song,L. Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Zpinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 × 60 ns) to be built will be presented briefly.
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재래 흑돼지와 중국 재래돈간의 Melanocortin Receptor 1(MC1R) 유전자의 유전자형 분석
이성수,양보석,정진관,고서봉,오성종,양영훈,김규일,이찬동,풍서당 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.1
PCR-RFLP analysis of Melanocortin receptor 1 (MC1R) gene was carried out to investigate the genotype distribution in Korean-Native and Chinese-Native pig breeds(Neijiang, Putian, Wannanhua and Jinhua). Allelic variants of MC1R in pigs were analyzed by digestion of BspH I , AccII and Hha I . Ncijiang. Wannanhua and Jinhua had only MC1R*2 allele which is considered to be typical genotype for Meishan and Large Black. Among 20 Korean-Native Pigs and 5 Putian pigs, 10 and 2 heads had the MC1R*3 allele (*2/3 or 3/3), respectively, which was detected in European pig breeds such as Hampshire, Large White, and Pietrain. The remaining animals possessed the genotype MC1R*2/2, probably reflecting the genetic introgression of MC1R*3 allele into Korean-Native and Putian pig breeds by the crossbreeding for improvement. The alleles MC1R*l and MC1R*4, which are considered to be typical allele for European Wild Boar with wild-type coat color and Duroc with red coat color, respectively, were not detected in pig breeds used in this experiment. These results indicate that the analysis of genotype frequencies of MC1R gene may be a useful tool for the conservation of Korean-Native and Chinese-Native pig breeds.
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GA-BASED PID AND FUZZY LOGIC CONTROL FOR ACTIVE VEHICLE SUSPENSION SYSTEM
J. Z. FENG,J. LI,F. YU 한국자동차공학회 2003 International journal of automotive technology Vol.4 No.4
Since the nonlinearity and uncertainties which inherently exist in vehicle system need to be considered in active suspension control law design, this paper proposes a new control strategy for active vehicle suspension systems by using a combined control scheme, i.e., respectively using a genetic algorithm (GA) based self-tuning PID controller and a fuzzy logic controller in two loops. In the control scheme, the PID controller is used to minimize vehicle body vertical acceleration, the fuzzy logic controller is to minimize pitch acceleration and meanwhile to attenuate vehicle body vertical acceleration further by tuning weighting factors. In order to improve the adaptability to the changes of plant parameters, based on the defined objectives, a genetic algorithm is introduced to tune the parameters of PID controller, the scaling factors, the gain values and the membership functions of fuzzy logic controller on-line. Taking a four degree-or-freedom nonlinear vehicle model as example, the proposed control scheme is applied and the simulations are carried out in different road disturbance input conditions. Simulation results show that the present control scheme is very effective in reducing peak values of vehicle body accelerations, especially within the most sensitive frequency range of human response, and in attenuating the excessive dynamic tire load to enhance road holding performance. The stability and adaptability are also showed even when the system is subject to severe road conditions, such as a pothole, an obstacle or a step input. Compared with conventional passive suspensions and the active vehicle suspension systems by using, e.g., linear fuzzy logic control, the combined PID and fuzzy control without parameters self-tuning, the new proposed control system with GA-based self-learning ability can improve vehicle ride comfort performance significantly and offer better system robustness.<br/>
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J.J. Wang,G.Z. Li,L.J. Feng,X.L. Chao,K. Zhao,Y.N. Feng 한국물리학회 2017 Current Applied Physics Vol.17 No.2
To clarify the influence of nano-graphite (NG) on the comprehensive performances of Nano-graphite/ PZT-PMN-PNN/RTV composites, composites with damping-absorption performances and storage-loss behaviors based on Room Temperature Vulcanizing silicone rubber (RTV), PZT matrix ceramics, NG as conductive agent were fabricated employing three steps methods of ball-milling, three-roller milling and pressing. The effects of NG on storage, loss and damping properties were investigated by the method of DMTA. Absorption and mechanical performances are measured by the method of standing wave tube and TG. The morphologies, chemical and phase structures of composites are characterized by SEM, XRD and IR. The research indicated that both doping of NG and the combination of PZT-PMN-PNN/RTV can be proposed to improve greatly the comprehensive performance of RTV matrixes. There would be more excellent comprehensive properties in NG/PZT-PMN-PNN/RTV composites as increasing rate of 65% in d33, storage modulus of 3010 MPa, loss modulus of 205 MPa, and damping coefficient tand of 0.26 and, absorption coefficients of 0.6e0.7 with the frequency of 400e1600 Hz. Also, the improvement in NG amounts for composites can lead to the enforcement of stress for NG/ZT-PMN-PNN/RTV composites, but it caused neither the preferential growth in any a single crystal surface, nor the appearance of solid solution.
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Feng, J.,Liu, X.,Wang, Y.Z.,Xu, Z.R. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.3
This experiment was conducted to determine the effect of dietary betaine (0, 0.125%) on performance, carcass composition, pork quality and hepatic betaine-homocysteine methyltransferase (BHMT) activity of crossbred finishing barrows. Three replicates of ten pigs were used for each treatment. The results showed that average daily gain, feed intake and feed conversion were not affected by betaine. Compared with the control group, pigs treated with betaine had a 8.17% (p<0.05) decrease in carcass fat percentage, and a 8.84% (p<0.05) reduction in 10th-rib backfat thickness, but dressing percentage, percentage lean, longissimus muscle area, and average backfat thickness were not affected. There were also no significant differences in muscle color score, marbling score, pork pH value and water loss rate between the control and betaine-treated groups. Hepatic betaine-homocysteine methyltransferase (BHMT) activity was significantly increased by 13.97% (p<0.05) when pigs were offered 0.125% betaine.
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GA-BASED PID AND FUZZY LOGIC CONTROL FOR ACTIVE VEHICLE SUSPENSION SYSTEM
Feng, J.-Z.,Li, J.,Yu, F. The Korean Society of Automotive Engineers 2003 International journal of automotive technology Vol.4 No.4
Since the nonlinearity and uncertainties which inherently exist in vehicle system need to be considered in active suspension control law design, this paper proposes a new control strategy for active vehicle suspension systems by using a combined control scheme, i.e., respectively using a genetic algorithm (GA) based self-tuning PID controller and a fuzzy logic controller in two loops. In the control scheme, the PID controller is used to minimize vehicle body vertical acceleration, the fuzzy logic controller is to minimize pitch acceleration and meanwhile to attenuate vehicle body vertical acceleration further by tuning weighting factors. In order to improve the adaptability to the changes of plant parameters, based on the defined objectives, a genetic algorithm is introduced to tune the parameters of PID controller, the scaling factors, the gain values and the membership functions of fuzzy logic controller on-line. Taking a four degree-of-freedom nonlinear vehicle model as example, the proposed control scheme is applied and the simulations are carried out in different road disturbance input conditions. Simulation results show that the present control scheme is very effective in reducing peak values of vehicle body accelerations, especially within the most sensitive frequency range of human response, and in attenuating the excessive dynamic tire load to enhance road holding performance. The stability and adaptability are also showed even when the system is subject to severe road conditions, such as a pothole, an obstacle or a step input. Compared with conventional passive suspensions and the active vehicle suspension systems by using, e.g., linear fuzzy logic control, the combined PID and fuzzy control without parameters self-tuning, the new proposed control system with GA-based self-learning ability can improve vehicle ride comfort performance significantly and offer better system robustness.
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S.-Z. Feng,L.-Y. Chen,J. Li,P.-H. Mao,R.-J. Zhang,X.-F. Li,Y.-X. Zheng 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.II
In this work, a series of SiO$_x$/SiO$_2$ superlattices were prepared, by using reactive evaporation, with different thicknesses of the SiO$_x$ layers. After being annealed at 1100 $^\circ$C, composite thin films with the nano-crystals of silicon (nc-Si) embedded in the SiO$_2$ layers were formed. The optical properties of the films were measured by using the spectroscopic ellipsometric (SE) method in the photon energy range from 1.5 to 4.5 eV at three different incidence angles of 65$^\circ$, 70$^\circ$ and 75$^\circ$. In terms of the ellipsometric data, the effective medium approximation (EMA) with the four-parameter Lorentz oscillator model was used to fit the spectra and to extract the optical dispersion of the nc-Si particles. We found that the dielectric functions of the composite films strongly depended on the volume fraction of nc-Si and the constant of the SiO$_2$ layers, which changed with the composition in the investigated spectrum range
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Development of the 3.7 GHz LHCD System on HL-2A
B. Lu,M. Huang,H. Zeng,X. Y. Bai,X. H. Mao,Z. H. Lu,J. Liang,Z. H. Kang,M. W. Wang,K. Feng,H. Wang,C. Wang,J. Q. Wang,S. Wei,T. Yao,Y. N. Bu,J. Feng,G. Y. Cheng,S. D. Song,D. H. Xia,J. Rao 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.8
A 2 MW-3.7 GHz lower hybrid current drive (LHCD) system is under development for physicsexperiments on the HL-2A device. The RF Power is generated by four TH2103A klystron amplifiersand propagates in the TE10 mode through WR284 waveguides. The transmission lines with a lengthof 20 m to 30 m are pressurized with 2 bars of nitrogen to decrease the possibility of arcing. Thelauncher, based on the passive-active multi-junction (PAM) concept, has been developed and iscurrently being realized. It was designed for a power spectrum peaked at Nk = 2.75 with goodcoupling properties over a wide range of plasma parameters. The four klystrons are fed by ahigh-voltage power supply (HVPS) based on the pulse step modulation (PSM) concept with a fastswitch-off time of less than ten μs. This system is expected to be in operation within 1 years and willexplore many international thermonuclear experimental reactor (ITER) related LH experiments inthe following years.
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Improvement of lower hybrid current drive systems for high-power and long-pulse operation on EAST
Wang M.,Liu L.,Zhao L.M.,Li M.H.,Ma W.D.,Hu H.C.,Wu Z.G.,Feng J.Q.,Yang Y.,Zhu L.,Chen M.,Zhou T.A.,Jia H.,Zhang J.,Cao L.,Zhang L.,Liang R.R.,Ding B.J.,Zhang X.J.,Shan J.F.,Liu F.K.,Ekedahl A.,Gonich 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11
Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m2 . Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 C, much below the permissible value of tungsten material (~1200 C). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-activemultijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5 toroidally from the 4.6 GHz LH system and is not magnetically connected
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