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Investigation of combined degrader for proton facility based on BDSIM/FLUKA Monte Carlo methods

Nuclear Science and Techniques 2022年第2期33卷 30-39页

作者： man-fen han Jin-Xing Zheng Xian-Hu Zeng Jun-Song Shen Hefei Institutes of Physical Science Chinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

The significant advantage of proton therapy over other particle-based techniques is in the unique physical characteristics of the Bragg *** can achieve a highly conformal dose distribution and maximize the probability of tumor control by varying the irradiation *** proton facilities use cyclotrons for fixed energy beam extraction and are equipped with degrader and collimator systems for energy modulation and emittance ***,interactions between charged particles and degrader materials inevitably cause beam loss and divergence and deteriorate beam performance,which present great challenges for downstream transport and clinical *** this work,we investigate a method of energy reduction by combining boron carbide and graphite in a degrader to obtain greater beam transmission at lower *** results demonstrate that the beam size and emittance at the exit of the combined degrader diverge less than those of multi-wedge one in the energy range of 70-160 ***,the transmission efficiency after the first dipole also shows improvements of 36.26%at 70 MeV and 70.55%at 110 *** a component with a high activity level,the degrader causes additional ambient radiation during *** induced radiation even remains several hours after system *** of material activation and induced radiation based on 1 h irradiation with a 400 nA beam current shows that the combined degrader has a definite advantage in shielding despite producing more secondary *** radioactivity and average ambient dose equivalent are reduced by 50%compared with the multiwedge degrader at the important cooling time of 1 *** 12 h and 24 h of cooling,the radiation levels of degraders decrease slightly due to the presence of long half-life residual *** average dose generated from the multi-wedge degrader is still 1.25 times higher than that of the combined one.

关键词： Proton therapy Degrader Boron carbide Transmission efficiency Radionuclide Ambient dose equivalent

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The medium-temperature dependence of jet transport coefficient in high-energy nucleus-nucleus collisions

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Nuclear Science and Techniques 2024年第7期35卷 173-191页

作者： man Xie Qing-Fei han En-Ke Wang Ben-Wei Zhang han-Zhong Zhang Key Laboratory of Atomic and Subatomic Structure and Quantum Control(MOE) Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of MatterInstitute of Quantum Matter South China Normal UniversityGuangzhou510006China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Guangdong Provincial Key Laboratory of Nuclear ScienceSouthern Nuclear Science Computing CenterSouth China Normal UniversityGuangzhou 510006China Key Laboratory of Quark and Lepton Physics(MOE)and Institute of Particle Physics Central China Normal UniversityWuhan430079China

The medium-temperature T dependence of the jet transport coefficient̂q was studied via the nuclear modification factor RAA(p_(T))and elliptical flow parameter v_(2)(p_(T))for large transverse momentum p_(T) hadrons in high-energy nucleus-nucleus *** a next-to-leading-order perturbative QCD parton model for hard scatterings with modified fragmentation functions due to jet quenching controlled by q,we check the suppression and azimuthal anisotropy for large p_(T) hadrons,and extract q by global fits to RAA(pT)and v_(2)(pT)data in A+A collisions at RHIC and LHC,*** numerical results from the best fits show that q∕T^(3) goes down with local medium-temperature T in the parton jet *** with the case of a constant q∕T^(3),the going-down T dependence of q∕T^(3) makes a hard parton jet to lose more energy near T_(c) and therefore strengthens the azimuthal anisotropy for large pT *** a result,v_(2)(p_(T))for large pT hadrons was enhanced by approximately 10%to better fit the data at RHIC/*** the first-order phase transition from QGP to the hadron phase and the additional energy loss in the hadron phase,v_(2)(p_(T))is again enhanced by 5-10%at RHIC/LHC.

关键词： Jet quenching Jet transport parameter Hadron suppression Elliptic flow coefficient Energy loss asymmetry

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Effect of initial ammonium concentration on a one-stage partial nitrification/anammox biofilm system:Nitrogen removal performance and the microbial community

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Journal of Environmental Sciences 2024年第9期143卷 176-188页

作者： Mengyu Zhou Yun han Yang Zhuo fen Yu Gaoyuan Hu Dangcong Peng School of Municipal and Environmental Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Shaanxi Key Laboratory of Environmental Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Key Laboratory of Northwest Water Resource Environment and EcologyMOEXi’an University of Architecture and TechnologyXi’an 710055China

One-stage partial nitrification coupled with anammox(PN/A)technology effectively reduces the energy consumption of a biological nitrogen removal *** nitrite-oxidizing bacteria(NOB)is essential for this technology to maintain efficient nitrogen removal *** ammonium concentration(IAC)affects the degree of inhibited *** this study,the effect of the IAC on a PN/A biofilm was investigated in a moving bed biofilm *** results showed that nitrogen removal efficiency decreased from 82.49%±1.90%to 64.57%±3.96%after the IAC was reduced from 60 to 20 mg N/L,while the nitrate production ratio increased from 13.87%±0.90%to 26.50%±3.76%.NOB activity increased to1,133.86 mg N/m^(2)/day after the IAC decreased,approximately 4-fold,indicating that the IAC plays an important inhibitory role in *** rate-limiting step in the mature biofilm of the PN/A system is the nitritation process and is not shifted by the *** analysis of the microbial community structure in the biofilm indicates that the IAC was the dominant factor in changes in community *** and *** were the main anammox bacteria,and Nitrosomonas and Nitrospira were the main AOB and NOB,*** did not affect the difference in growth between *** and ***,modulating the IAC promoted the PN/A process with efficient nitrogen removal performance at medium to low ammonium concentrations.

关键词： Biological nitrogen removal Partial nitrification Anammox Ammonium concentration Biofilm

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Laser welding study of vacuum sintered HUST-1 lunar regolith simulant

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Science China(Technological Sciences) 2024年第9期67卷 2905-2918页

作者： han WenBin DING LieYun ZHOU Cheng ZHOU Yan DANG fen National Center of Technology Innovation for Digital Construction Huazhong University of Science and TechnologyWuhan 430074China School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 730074China

Efforts are underway to establish a permanent lunar base on the Moon. In situ lunar regolith is anticipated to be useful as a building material after sintering. However, sintering lunar regolith into a large-scale structure presents challenges. Therefore, the key to lunar construction lies in assembling multiple small-sized sintered modules into a stable, large-sized structure. This study explored the feasibility of welding the sintered HUST-1 lunar regolith simulant(HLRS) using a laser device and conducted experiments using lasers of varying power. The microstructure, mineral composition, element distribution, and shear strength of the welded joint were investigated. A few low-melting minerals were fused and vaporized during welding, leading to the generation of thermal decomposition gas. Furthermore, the welded joint exhibited numerous micro-cracks, pores, and bubbles,resulting in reduced weld shear strength. Finally, the influence of laser power on weld shear strength was investigated, revealing that the highest shear strength(15.69 N/cm) was achieved at a laser power of 1000 W. This study demonstrates the feasibility of laser welding of sintered HLRS for the first time, with potential applications in lunar base construction.

关键词： lunar regolith vacuum sintering laser welding weld shear strength lunar base

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Robust reinforcement learning with UUB guarantee for safe motion control of autonomous robots

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Science China(Technological Sciences) 2024年第1期67卷 172-182页

作者： ZhanG RuiXian han YiNing SU man LIN Zefeng LI HaoWei ZhanG LiXian School of Astronautics Harbin Institute of TechnologyHarbin 150001China School of management Harbin Institute of TechnologyHarbin 150001China Beijing Institute of Tracking and Telecommunication Technology Beijing 100094China

This paper addresses the issue of safety in reinforcement learning(RL)with disturbances and its application in the safety-constrained motion control of autonomous *** tackle this problem,a robust Lyapunov value function(rLVF)is *** rLVF is obtained by introducing a data-based LVF under the worst-case disturbance of the observed *** the rLVF,a uniformly ultimate boundedness criterion is *** criterion is desired to ensure that the cost function,which serves as a safety criterion,ultimately converges to a range via the policy to be ***,to mitigate the drastic variation of the rLVF caused by differences in states,a smoothing regularization of the rLVF is *** train policies with safety guarantees under the worst disturbances of the observed states,an off-policy robust RL algorithm is *** proposed algorithm is applied to motion control tasks of an autonomous vehicle and a cartpole,which involve external disturbances and variations of the model parameters,*** experimental results demonstrate the effectiveness of the theoretical findings and the advantages of the proposed algorithm in terms of robustness and safety.

关键词： motion control reinforcement learning robustness stability

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Understanding the dehydrogenation properties of Mg(0001)/MgH_(2)(110)interface from first principles

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Materials Reports(Energy) 2024年第1期4卷 89-94页

作者： Jianchuan Wang Bo han Zhiquan Zeng Shiyi Wen fen Xu Yong Du State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083PR China Powder Metallurgy Research Institute Central South UniversityChangsha410083PR China Guangxi Key Laboratory of Information Materials Guilin University of Electronic TechnologyGuilin541004PR China

Magnesium hydride is one of the most promising solid-state hydrogen storage materials for on-board *** desorption from MgH_(2) is accompanied by the formation of the Mg/MgH_(2) interfaces,which may play a key role in the further dehydrogenation *** this work,first-principles calculations have been used to understand the dehydrogenation properties of the Mg(0001)/MgH_(2)(110) *** is found that the Mg(0001)/MgH_(2)(110) interface can weaken the Mg-H *** removal energies for hydrogen atoms in the interface zone are significantly lower compared to those of bulk MgH_(2).In terms of H mobility,hydrogen diffusion within the interface as well as into the Mg matrix is *** calculated energy barriers reveal that the migration of hydrogen atoms in the interface zone is easier than that in the bulk MgH_(2).Based on the hydrogen removal energies and diffusion barriers,we conclude that the formation of the Mg(0001)/MgH_(2)(110) interface facilitates the dehydrogenation process of magnesium hydride.

关键词： Magnesium hydrides First-principles calculation Hydrogen storage materials Interface Hydrogen desorption

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V0405 Dra:A New Deep and Low Mass Ratio Contact Binary with Extremely Fast Decrease in the Orbital Period

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Research in Astronomy and Astrophysics 2024年第6期24卷 287-293页

作者： Chao-Yue Li Lin-Qiao Jiang Jie Zheng Yi-man Liu Xiao-Yu Long Min Sun han-Lu Zhang Xiao-man Tian School of Science Leshan Normal UniversityLeshan 614000China Center for Applied Optics Research Leshan Normal UniversityLeshan 614000China Key Laboratory of Detection and Application of Space Effect in Southwest Sichuan Leshan 614000China CAS Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Aeronautics Shandong Jiaotong UniversityJinan 250000China

V0405 Dra is a W UMa-type binary *** on the TESS data,we have conducted an orbital period study and performed a light curve analysis for the *** orbital period study reveals that the O-C curve for V0405 Dra exhibits secular decrease at an extremely high rate of d P/dt=-2.71×10^(-6)day year^(-1),along with periodic variations characterized by an amplitude of A_(3)=0.0032 day and a period of P_(3)=1.413 *** orbital periodic change is possibly due to the light-travel time effect resulting from an additional third body in the system,for which we estimate a minimum mass of M_(3)=0.77M_(⊙).By employing the 2013 version of the Wilson-Devinney(W-D)method to synthesize a light curve,we derived photometric solutions indicating that V0405 Dra is a new deep(f=68.7%)and low-mass ratio(q=0.175)contact *** fast decrease in its orbital period is likely caused by mass transfer from the more massive primary star to the less massive secondary star,or due to angular momentum *** further mass transfer and loss of angular momentum,the binary will gradually evolve into a tighter contact configuration,eventually leading to a merger into a single star,following the evolutionary paths suggested for such deep and low mass ratio contact binaries.

关键词： (stars:)binaries(including multiple):close (stars:)binaries:eclipsing stars:individual(V0405 Dra)

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Higher-dimensional Chen-Lee-Liu equation and asymmetric peakon soliton

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Chinese Physics B 2024年第4期33卷 224-229页

作者：韩巧红贾曼 School of Physical Science and Technology Ningbo UniversityNingbo 315211China

Integrable systems play a crucial role in physics and *** particular,the traditional(1+1)-dimensional and(2+1)-dimensional integrable systems have received significant attention due to the rarity of integrable systems in higher *** studies have shown that abundant higher-dimensional integrable systems can be constructed from(1+1)-dimensional integrable systems by using a deformation *** we establish a new(2+1)-dimensional Chen-Lee-Liu(C-L-L)equation using the deformation algorithm from the(1+1)-dimensional C-L-L *** new system is integrable with its Lax pair obtained by applying the deformation algorithm to that of the(1+1)-*** is challenging to obtain the exact solutions for the new integrable system because the new system combines both the original C-L-L equation and its reciprocal *** traveling wave solutions are derived in implicit function expression,and some asymmetry peakon solutions are found.

关键词： higher dimensional Chen-Lee-Liu equation Lax integrable system deformation algorithm implicit traveling wave solutions

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AtRKD5 inhibits the parthenogenic potential mediated by AtBBM

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Journal of Integrative Plant Biology 2024年第7期66卷 1517-1531页

作者： Qiyan Liu Dongfen han Denghu Cheng Jinfan Chen Shujuan Tian Jiafa Wang man Liu Li Yuan State Key Laboratory of Crop Stress Resistance and High‐Efﬁciency Production College of HorticultureNorthwest A&F UniversityYangling 712100China

Parthenogenesis,the development of unfertilized egg cells into embryos,is a key component of ***(BABY BOOM),a crucial regulator of embryogenesis in Arabidopsis,possesses the capacity to shift nutritional growth toward reproductive ***,the mechanisms underlying AtBBM-induced parthenogenesis remain largely unexplored in dicot *** findings revealed that in order to uphold the order of sexual reproduction,the embryo-specific promoter activity of AtBBM as well as repressors that inhibit its expression in egg cells combine to limiting its ability to induce ***,AtRKD5,a RWPRK domain-containing(RKD)transcription factor,binds to the 3'end of AtBBM and is identified as one of the inhibitory factors for AtBBM expression in the egg *** the atrkd5 mutant,we successfully achieved enhanced ectopic expression of AtBBM in egg cells,resulting in the generation of haploid offspring via parthenogenesis at a rate of 0.28%.Furthermore,by introducing chimeric Arabidopsis and rice BBM genes into the egg cell,we achieved a significant 4.6-fold enhancement in haploid induction through the atdmp8/9 *** findings lay a strong foundation for further exploration of the BBM-mediated parthenogenesis mechanism and the improvement of haploid breeding efficiency mediated by the dmp8/9 mutant.

关键词： AtBBM atdmp AtRKD5 haploid induction parthenogenesis

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Experimental evaluation of factors affecting performance of concentrating photovoltaic/thermal system integrated with phase‐change materials(PV/T‐CPCM)

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Energy Storage and Saving 2024年第1期3卷 30-41页

作者： Zhaoyang Luan Lanlan Zhang Xiangfei Kong han Li man Fan School of Energy and Environmental Engineering Hebei University of TechnologyTianjin300401China School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China

The photovoltaic/thermal(PV/T)system is a promising option for countering energy *** improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly applied to construct a concentrating photovoltaic/thermal system integrated with phase-change materials(PV/T-CPCM).An open-air environment is used to analyze the effects of different parameters and the intermittent operation strategy on the system *** results indicate that the short-circuit current and open-circuit voltage are positively correlated with the solar irradiance,but the open-circuit voltage is negatively correlated with the temperature of the PV *** the solar irradiance is 500 W⋅m^(−2) and the temperature of the PV modules is 27.5℃,the short-circuit current and open-circuit voltage are 1.0 A and 44.5 V,*** solar irradiance results in higher thermal power,whereas the thermal efficiency is under lower solar irradiance(136.2-167.1 W⋅m^(−2) is twice under higher solar irradiance(272.3-455.7 W⋅m^(−2))).In addition,a higher mass flow rate corresponds to a better cooling effect and greater pump energy *** the mass flow rate increases from 0.01 to 0.02 kg⋅s^(-1),the temperature difference between the inlet and outlet decreases by 1.8℃,and the primary energy-saving efficiency decreases by 0.53%.The intermittent operation of a water pump can reduce the energy consumption of the system,and the combination of liquid cooling with PCMs provides better thermal regulation and energy-saving effects under various conditions.

关键词： Compound parabolic concentrator Factor analysis Open-air experiment Phase-change materials Photovoltaic/thermal system

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