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Targets capture by distributed active swarms via bio-inspired reinforcement learning

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 210-221页

作者： Kun Xu Yue Li Jun Sun Shuyuan Du Xinpeng Di Yuguang Yang Bo Li Institute of Biomechanics and Medical engineering Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua University Institute of nuclear and New Energy Technology Tsinghua University Shanghai Aerospace Control Technology Institute Shanghai Key Laboratory of Aerospace Intelligent Control Technology College of Automation engineering Nanjing University of Aeronautics and Astronautics

Natural swarms arranged from cells to herds are usually decentralized but display intriguing collective intelligence in coordinating individuals across large scales to efficiently achieve their common goals. Learning from nature may provide new strategies for controlling collective dynamics of synthetic swarms to accomplish specific functions. Here, we present a bioinspired computational framework that steers distributed active swarms to collectively capture and merge targets via reinforcement learning. We exploit collective milling structures of natural herds to cage the targets, and adopt a switching control policy inspired by sperms' chiral dynamics to optimize the trajectories of individuals, through which the active swarms can selforganize to enclose single or multiple distant targets in a dynamical, adaptive and scalable manner. There exists a critical swarm size, beyond which the excessive competition between agents would generate large mechanical forces, leading to capture instability but enabling the transition from short-distance to long-distance merging capture of multiple targets. This work provides physical insights into distributed active swarms and could offer a multilevel, decentralized strategy toward controlling swarm robotics in wide applications such as bio-medical devices, machine immunity, and target clearance.

关键词： swarm intelligence robotics multi-tasks artificial intelligence bionics

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Resistance and Reactance of Monopole Fields Induced by a Test Charge Drifting Off-Axis in a Cold and Collisional Cylindrical Plasma

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Chinese Physics Letters 2018年第8期35卷 49-53页

作者： M.S.Bawa'aneh A.M.Al-Khateeb Y.-c.Ghim department of Physics Yarmouk University department of nuclear and quantum engineering KAIST

We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the electromagnetic field components at all interfaces, the induced monopole electromagnetic fields in the plasma are obtained in the frequency domain. An expression for the plasma electric resistance and reactance is derived and analyzed numerically for some representative parameters. Near the plasma resonant frequency, the plasma resistance evolves with frequency like a parallel RLC resonator with peak resistance at the plasma frequency pe, while the plasma reactance can be capacitive or inductive in nature depending on the frequency under consideration.

关键词： In Resistance and Reactance of Monopole Fields Induced by a Test Charge Drifting Off-Axis in a Cold and Collisional Cylindrical Plasma

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An in-situ Raman spectroscopic study on potential-pO^(2-) phase diagram of lanthanum in LiCl-KCl eutectic melt

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Journal of Rare Earths 2020年第7期38卷 793-800,I0004页

作者： Seung Park Jong-IL Yun department of nuclear and quantum engineering.KAIST Yuseong-guDaejeon 34141Republic of Korea

The oxidative reaction between lanthanum trichloride and oxide ion was studied in the molten LiCl-KCl eutectic at 773 K by in-situ Raman spectroscopy using an yttria-stabilized zirconia electrode in conjunction with electrochemical *** formation of lanthanum oxychloride,LaOCl(s),was confirmed by studying the vibrational properties of crystalline LaOCl and X-ray diffraction *** solubility product of LaOCl in the LiCl-KCl molten eutectic at 773 K is found to be pKsp(LaOCl)=7.569±0.100,by combining the results of Raman spectroscopy and potentiometric titration with the addition of barium *** use of Raman spectroscopic quantitation of dissolved lanthanum ions in the system allows faster and more accurate determination of the stable phase of lanthanum as well as the solubility product of LaOCl compared with that measured by potentiometric titration *** on experimentally obtained pKsp and standard equilibrium potentials,the potentialpO2- phase diagram of lanthanum in the molten LiCl-KCl eutectic was reported.

关键词： Lanthanum Solubility product E-pO2-diagram Raman spectroscopy Chloride molten salt Rare earths

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Selective adsorption and stable solidification of radioactive cesium ions by porous silica gels loaded with insoluble ferrocyanides

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Science China Chemistry 2014年第11期57卷 1470-1476页

作者： YIN XiangBiao WU Yan MIMURA Hitoshi NIIBORI Yuichi WEI YueZhou department of quantum Science and Energy engineering Tohoku University School of nuclear Science and engineering Shanghai Jiao Tong University

Development of highly functional cesium selective adsorbents for the decontamination of high-activity-level water(HALW) from the Fukushima NPP-1 accident is very urgent. In order to selectively adsorb the radioactive cesium, three kinds of novel porous silica gels loaded with insoluble ferrocyanides(SLFC) were prepared using a successive impregnation/precipitation method. Based on the results of previous research, the SLFC composites have relatively large uptake ratio above 95%, distribution coefficients(Kd) above 103 cm3/g, and excellent adsorption kinetics even in seawater. The solidification results also indicate that zeolites have an excellent Cs immobilization characteristic, gas-trapping and self-sintering abilities, and low leachability. We chose three kinds of SLFC composites to achieve the optimization of solidification by mixing with nine kinds of additives at high temperatures(up to 1200 °C). The Cs contents in the three composites were estimated to be below 30% of the initial contents and decreased with the three stages at calcination temperatures ranging from 25 to 1200 °C. By contrast, the Cs immobilization ratio was markedly lowered by mixing with additives: of those, allophane had the best immobilization result. By increasing the additive ratio to 50 wt%, the Cs immobilization ratio became almost 100% and no volatilization of Cs was detected even after calcination at 1200 °C. This result indicates that calcination of the mixture of SLFC composites after adsorbing Cs+ ions and specific additives under appropriate ratio is effective for stable solidification.

关键词： Cs zeolites high-activity-level water(HALW) insoluble ferrocyanides stable solidification

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Mo and Ta addition in NbTiZr medium entropy alloy to overcome tensile yield strength-ductility trade-off

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Journal of Materials Science & Technology 2022年第14期109卷 176-185页

作者： Muhammad Akmal Hyun Woo Seong Ho Jin Ryu department of Materials Science and engineering KAISTDaejeonYuseong-gu 34141South Korea department of nuclear and quantum engineering KAISTDaejeonYuseong-gu 34141South Korea

In this study,single-phase NbTiZr and NbTiZr(MoTa)_(0.1) medium-entropy alloys(MEAs)were investigated for their use in biomedical *** alloys were prepared by arc melting,and were then cold-rolled,annealed,and characterized in terms of phase analysis,mechanical properties,fractography,and wear *** alloys showed a single body-centered cubic phase with superior mechanical,and tribological properties compared to commercially available biomedical *** and Ta-containing MEAs showed higher tensile yield strength(1060±18 MPa)and higher tensile ductility(~20%),thus overcoming the strength-ductility trade-off with no signs of transformation-induced plasticity,twinning,or *** generalized stacking fault energy(GSFE)calculations on the{112}slip system by the first-principles calculations based on density functional theory showed that the addition of less than0.2 molar fraction of Mo and Ta lowers the GSFE *** behavior posits the increase in ductility of the alloy by facilitating slips although strength is also increased by solid solution *** wear resistance of both alloys against hardened steel surfaces was superior to that of commercial biomedical ***,we concluded that NbTiZr(MoTa)_(0.1)MEA with good tensile ductility is a potential candidate for biomedical implants.

关键词： Medium-entropy alloys Wear-resistant Biomedical implants Solid solution hardening Staking fault energy

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Oxidation behavior of high-strength FeCrAl alloys in a high-temperature supercritical carbon dioxide environment

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Progress in Natural Science:Materials International 2018年第6期28卷 731-739页

作者： Hongsheng Chen Sung Hwan Kim Chongsheng Long Chaewon Kim Changheui Jang department of nuclear and quantum engineering Korea Advanced Institute of Science and Technology Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of China

The oxidation behavior of three high-strength FeCrAl alloys was investigated in supercritical carbon dioxide environment at 650 ℃. After exposure for 500 h, the weight gains of the FeCrAl alloys gradually decreased with increasing Al content. The oxide scales are primarily composed of α-Al;O;and spinel oxides. With increasing Al content, the amount of α-Al;O;increases and the C content decreased in the oxide scale and sub-scale ***, larger（Nb,Mo）C carbides formed in the sub-scale matrix and their number decreased with the increase of Al content.

关键词： High-strength FeCrAl alloy Supercritical carbon dioxide Oxidation α-Al2O3

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Empirical correlations for predicting the self-leveling behavior of debris bed

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nuclear Science and Techniques 2013年第1期24卷 43-52页

作者： CHENG Songbai YAMANO Hidemasa SUZUKI Tohru TOBITA Yoshiharu NAKAMURA Yuya ZHANG Bin MATSUMOTO Tatsuya MORITA Koji Advanced nuclear System R&D Directorate Japan Atomic Energy Agency (JAEA) department of Applied quantum Physics and nuclear engineering Kyushu University

Studies on the self-leveling behavior of debris bed are crucial for the assessment of core-disruptive accident (CDA) occurred in sodium-cooled fast reactors (SFR). To clarify this behavior over a comparatively wider range of gas velocities, a series of experiments were performed by injecting nitrogen gas uniformly from a pool bottom. Current experiments were conducted in a cylindrical tank, in which water, nitrogen gas and different kinds of solid particles, simulate the coolant, vapor (generated by coolant boiling) and fuel debris, respectively. Based on the quantitative data obtained (mainly the time variation of bed inclination angle), with the help of dimensional analysis technique, a set of empirical correlations to predict the self-leveling development depending on particle size, particle density and gas injection velocity was proposed and discussed. It was seen that good agreement could be obtained between the calculated and experimental values. Rationality of the correlations was further confirmed through detailed analyses of the effects of experimental parameters such as particle size, particle density, gas flow rate and boiling mode. In order to facilitate future analyses and simulations of CDAs in SFRs, the obtained results in this work will be utilized for the validations of an advanced fast reactor safety analysis code.

关键词：自流平行为模拟冷却水预测气体速度注入氮气粒子密度实验值

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Design Features and Commissioning of the Versatile Experiment Spherical Torus (VEST) at Seoul National University

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Plasma Science and Technology 2013年第3期15卷 244-251页

作者： K.J.CHUNG Y.H.AN B.K.JUNG H.Y.LEE C.SUNG Y.S.NA T.S.HAHM Y.S.HWANG department of nuclear engineering Seoul National University

A new spherical torus called VEST （Versatile Experiment Spherical Torus） is designed, constructed and successfully commissioned at Seoul National University. A unique design feature of the VEST is two partial solenoid coils installed at both vertical ends of a center stack, which can provide sufficient magnetic fluxes to initiate tokamak plasmas while keeping a low aspect ratio configuration in the central region. According to initial double null merging start-up scenario using the partial solenoid coils, apprdpriate p6wer supplies for driving a toroidal field coil, outer poloidal field coils, and the partial solenoid Coils are fabricated and successfully commissioned. For reliable start-up, a pre-ionization system with two cost-effective homemade magnetron power supplies is also prepared. In addition, magnetic and spectroscopic diagnostics with appropriate data acquisition and control systems are well prepared for initial operation of the device. The VEST is ready for tokamak plasma operation by completing and commissioning most of the designed components.

关键词： spherical torus partial solenoids double null merging start-up

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Improvements in methodology to determine feedback reactivity coefficients

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nuclear Science and Techniques 2019年第4期30卷 91-104页

作者： Faisal Qayyum Muhammad Rizwan Ali Awais Zahur R.Khan department of nuclear engineering Pakistan Institute of Engineering and Applied Sciences (PIEAS) department of nuclear engineering Pakistan Institute of Engineering and Applied Sciences(PIEAS)

The reactivity of a nuclear reactor is the most important safety and operating parameter. Due to short reactor period, the Light Water Reactor(LWR) designs require the compensations of rapid unfavorable reactivity increases. The increase in fuel or moderator temperature leads to compensate the reactivity jumps as inherent safety characteristics. The safe and reliable reactor operation requires the accurate assessment of these reactivity changes. This paper highlights the improvements in the methodology to determine the feedback reactivity changes in IAEA MTR benchmark. This method incorporates the reactivity effects of fuel temperature in moderator regions and vice versa. For this purpose, a detailed 3D model of the IAEA 10 MW MTR benchmark reactor is developed employing OpenMC computer code. OpenMC is a probabilistic computer code for neutronic calculations. This work uses temperature-dependent JEFF 3.2 cross-sectional library. The model is validated against the reference results of eigenvalues for control rods(inserted and in fully withdrawn position), control rod reactivity worth, averaged thermal flux in the central flux trap, and power fraction for each fuel element at beginning of life. The validated model is applied to simulate the feedback reactivity coefficients against the conventional reference results. In order to improve the methodology, the effect of the moderator temperature and void on fuel is incorporated to obtain a more realistic value of the fuel temperature ***, the moderator temperature coefficient and void coefficient are improved by incorporating the coupling effects of fuel temperature on moderator. This methodology can be applied to improve the LWR designs.

关键词： OpenMC MTR benchmark Reactivity feedback coefficients Fuel temperature coefficient Moderator temperature coefficient Void coefficient of reactivity

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Cluster size and substrate temperature affecting thin film formation during copper cluster deposition on a Si(001) surface

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Chinese Physics B 2012年第11期21卷 190-197页

作者：龚恒风吕炜王鲁闽李公平 School of nuclear Science and Technology Lanzhou University department of Mechanical engineering University of Michigan department of nuclear engineering and Radiological Science University of Michigan

The soft deposition of Cu clusters on a Si （001） surface was studied by molecular dynamics simulations. The embedded atom method, the Stillinger-Weber and the Lennar-Jones potentials were used to describe the interactions between the cluster atoms, between the substrate atoms, and between the cluster and the substrate atoms, respectively. The Cu13, Cu55, and Cu147 clusters were investigated at different substrate temperatures. We found that the substrate temperature had a significant effect on the Cn147 cluster. For smaller Cu13 and Cu55 clusters, the substrate temperature in the range of study appeared to have little effect on the mean center-of-mass height. The clusters showed better degrees of epitaxy at 800 K. With the same substrate temperature, the Cu55 cluster demonstrated the highest degree of epitaxy, followed by Cu147 and then Cu13 clusters. In addition, the Cu55 cluster showed the lowest mean center-of-mass height. These results suggested that the Cu55 cluster is a better choice for the thin-film formation among the clusters considered. Our studies may provide insight into the formation of desired Cu thin films on a Si substrate.

关键词： copper cluster deposition epitaxy diffusion

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