Preliminary electromagnetic analysis of the COOL blanket for CFETR

The supercritical CO_(2)cOoled Lithium-Lead(COOL)blanket has been designed as one advanced blanket candidate for the Chinese Fusion Engineering Test Reactor(CFETR).This work focuses on the electromagnetic(EM)loads(Maxwell force and Lorentz force)acting on the COOL blanket,which are important mechanical loads in further structural analysis of the COOL blanket.A 3D electromagnetic analysis is performed using the ANSYS finite element method to obtain EM loads on the COOL blanket in this study.At first,the magnetic scalar potential(MSP)method is used to obtain the magnetic field and the Maxwell force on the COOL blanket.Then,the magnetic vector potential(MVP)method is performed during a plasma disruption event to get the eddy current distribution.At last,a multi-step method is adopted for the calculation of the Lorentz force and the torque.The maximum Lorentz forces of inboard and outboard blanket structural components are 5624 kN and 2360 kN respectively.

A Constrained Local Neighborhood Approach for Efficient Markov Blanket Discovery in Undirected Independent Graphs

When learning the structure of a Bayesian network,the search space expands significantly as the network size and the number of nodes increase,leading to a noticeable decrease in algorithm efficiency.Traditional constraint-based methods typically rely on the results of conditional independence tests.However,excessive reliance on these test results can lead to a series of problems,including increased computational complexity and inaccurate results,especially when dealing with large-scale networks where performance bottlenecks are particularly evident.To overcome these challenges,we propose a Markov blanket discovery algorithm based on constrained local neighborhoods for constructing undirected independence graphs.This method uses the Markov blanket discovery algorithm to refine the constraints in the initial search space,sets an appropriate constraint radius,thereby reducing the initial computational cost of the algorithm and effectively narrowing the initial solution range.Specifically,the method first determines the local neighborhood space to limit the search range,thereby reducing the number of possible graph structures that need to be considered.This process not only improves the accuracy of the search space constraints but also significantly reduces the number of conditional independence tests.By performing conditional independence tests within the local neighborhood of each node,the method avoids comprehensive tests across the entire network,greatly reducing computational complexity.At the same time,the setting of the constraint radius further improves computational efficiency while ensuring accuracy.Compared to other algorithms,this method can quickly and efficiently construct undirected independence graphs while maintaining high accuracy.Experimental simulation results show that,this method has significant advantages in obtaining the structure of undirected independence graphs,not only maintaining an accuracy of over 96%but also reducing the number of conditional independence tests by at least 50%.This significant performance improvement is due to the effective constraint on the search space and the fine control of computational costs.

Neutronics analysis of a subcritical blanket system driven by a gas dynamic trap-based fusion neutron source for ^(99)Mo production

Gamma-emitting radionuclide ^(99m)Tc is globally used for the diagnosis of various pathological conditions owing to its ideal single-photon emission computed tomography (SPECT) characteristics.However,the short half-life of ^(99m)Tc (T_(1/2)=6 h)makes it difficult to store or transport.Thus,the production of ^(99m)Tc is tied to its parent radionuclide ^(99)Mo (T_(1/2)=66 h).The major production paths are based on accelerators and research reactors.The reactor process presents the potential for nuclear proliferation owing to its use of highly enriched uranium (HEU).Accelerator-based methods tend to use deuterium–tritium(D–T) neutron sources but are hindered by the high cost of tritium and its challenging operation.In this study,a new ^(99)Mo production design was developed based on a deuterium–deuterium (D–D) gas dynamic trap fusion neutron source (GDT-FNS) and a subcritical blanket system (SBS) assembly with a low-enriched uranium (LEU) solution.GDT-FNS can provide a relatively high-neutron intensity,which is one of the advantages of ^(99)Mo production.We provide a Monte Carlo-based neutronics analysis covering the calculation of the subcritical multiplication factor (k_(s)) of the SBS,optimization design for the reflector,shielding layer,and ^(99)Mo production capacity.Other calculations,including the neutron flux and nuclear heating distributions,are also provided for an overall evaluation of the production system.The results demonstrated that the SBS meets the nuclear critical safety design requirement (k_(s)<0.97) and maintained a high ^(99)Mo production capacity.The proposed system can generate approximately 157 Ci ^(99)Mo for a stable 24 h operation with a neutron intensity of 1×10^(14) n/s,which can meet 50%of China’s demand in 2025.

Joint target assignment and power allocation in the netted C-MIMO radar when tracking multi-targets in the presence of self-defense blanket jamming

The netted radar system(NRS)has been proved to possess unique advantages in anti-jamming and improving target tracking performance.Effective resource management can greatly ensure the combat capability of the NRS.In this paper,based on the netted collocated multiple input multiple output(CMIMO)radar,an effective joint target assignment and power allocation(JTAPA)strategy for tracking multi-targets under self-defense blanket jamming is proposed.An architecture based on the distributed fusion is used in the radar network to estimate target state parameters.By deriving the predicted conditional Cramer-Rao lower bound(PC-CRLB)based on the obtained state estimation information,the objective function is formulated.To maximize the worst case tracking accuracy,the proposed JTAPA strategy implements an online target assignment and power allocation of all active nodes,subject to some resource constraints.Since the formulated JTAPA is non-convex,we propose an efficient two-step solution strategy.In terms of the simulation results,the proposed algorithm can effectively improve tracking performance in the worst case.

一种近似Markov Blanket最优特征选择算法

特征选择可以有效改善分类效率和精度,传统方法通常只评价单个特征,较少评价特征子集.在研究特征相关性基础上,进一步划分特征为强相关、弱相关、无关和冗余四种特征,建立起Markov Blanket理论和特征相关性之间的联系,结合Chi-Square检验统计方法,提出了一种基于前向选择的近似Markov Blanket特征选择算法,获得近似最优的特征子集.实验结果证明文中方法选取的特征子集与原始特征子集相比,以远小于原始特征数的特征子集获得了高于或接近于原始特征集的分类结果.同时,在高维特征空间的文本分类领域,与其它的特征选择方法OCFS,DF,CHI,IG等方法的分类结果进行了比较,在20Newsgroup文本数据集上的分类实验结果表明文中提出的方法获得的特征子集在分类时优于其它方法.

基于Markov blanket和互信息的集成特征选择算法

针对大量无关和冗余特征的存在可能降低分类器性能的问题,提出一种基于近似Markov blanket和动态互信息的特征选择算法并将其应用于集成学习,进而得到一种集成特征选择算法。该集成特征选择算法运用Bagging方法结合提出的特征选择方法生成基分类器,并引入基分类器差异度进行选择性集成,最后用加权投票法融合所选基分类器的识别结果。通过仿真实验验证算法的有效性,以支持向量机(support vector machine,SVM)为分类器,在公共数据集UCI上进行试验,并与单SVM及经典的Bagging集成算法和特征Bagging集成算法进行对比。实验结果显示,该方法可获得较高的分类精度。

Effects of Seed Rate on Root Twining Power and Seedling Quality of Machine-transplanted Super Rice

In order to investigate the effects of seed rate on root twining power and seedling quality of machine-transplanted super rice cultivars, Yongyou 12 and Zhongzheyou No.l, total 6 seed rates were arranged, and the growth characteris- tics, quality and root twining power of machine-transplanted rice seedlings were studied. The results showed that seed rate had great effects on root twining power and qualityof rice seedlings; with the increase of seed rate, the root twining power of rice seedlings was increased, but the quality of rice seedlings was significantly reduced; under the condition of high seed rate, rice seedlings were weak with less accumulate dry matter and nonuniform growth, and the proportion of weak seedlings was higher. When the seed rate of both rice cultivars was reduced by 10 g/tray, the average seedling height was increased by 0.5 cm, leaf age was increased by 0.1, stem base diameter was increased by 0.1 cm, and root number per plant was increased by 0.3. When the seed rate was increased by 10 g/tray, the accumulated dry matter per plant was reduced by 5.1 mg. With the increase of seed rate, the seedling quality of Zhongzheyou No.1 was decreased rapidly, and the proportion of weak seedlings was increased rapidly. However, Yongyou 12 has a larger elasticity in seed rate. When the seed rate reached to 50 g/tray, blanket seedlings of Yongy- ou 12 were nursed with uniform growth and higher quality, but the shoots were sparse with lower leaf area index. However, when the seed rate was up to 50 g/tray, blanket seedlings of Zhongzheyou No.1 were nursed with uniform growth and higher quality, as well as higher-density shoots. From a comprehensive point of view, the optimum seed rates of Yongyou 12 and Zhongzheyou No.1 were 65 and 50 g/tray, respectively.

H_2S removal in landfill leachate treatment using UASB reactor

Leachate from a sanitary landfill site in Chengdu, China is treated using a hybrid-UASB reactor at pilot scale. H2S, resulting from the anaerobic bioconversion process of sulfate-reducing bacteria（SRB）, inhibits the growth and activity of methane-producing bacteria（MPB）and poses serious problems of pollution, so FeCl3is used for H2S removal. The results show that the system performs well in the treatment process. COD removal generally increases with the increase in the organic loading rate（OLR）, while the sulfate removal decreases slowly. As the OLR is higher than 7 kgCOD/（m3·d）, both COD and sulfate removal tend to be stable. When the reactor is operated at the design load of 9 kgCOD/（m3·d）, COD and sulfate removal remain about 79% and 91%, respectively. At the same time, the percentage of COD removed by SRB（CODSRB）also decreases from 8.9% to 4.0%. With FeCl3 addition, COD removal increases to 83%, while sulfate removal and CODSRBfurther decrease to 89% and 1.89%, respectively. According to the mass balance, nearly 82% of the sulfur is prevented from converting into H2S. Moreover, when the FeCl3 dosage is more than 1.6 g/L leachate, H2S can be removed totally from the biogas. Therefore, the application of FeCl3 for H2S removal in leachate treatment using the UASB reactor is very suitable and viable.

氟磺胺草醚生产中废水的处理

从试验、设计、调试等方面介绍了可生化性差、氯离子浓度高的氟磺胺草醚生产中废水的处理,该废水经“电解-UA SB-SBR”工艺处理后,出水水质符合《污水综合排放标准(GB 8978-1996)》中二级标准,每立方米废水的处理成本为4.10元.

改进Flower型超临界水冷快堆负空泡反应性初步分析设计

超临界水冷快堆结构简化,堆芯功率密度高并且不存在沸腾危机,是一种比较有前途的先进核能系统.但潜在的正空泡反应性系数是需要认真考虑的安全问题.本文建立了改进Flower型超临界水冷快堆堆芯模型,并通过对堆芯分区布置,冷却剂密度分层、MOX燃料合理设计、燃料富集度轴向分层布置,blanket组件盒厚度增加及内部通道采用贫铀冷却的方案,获得了负的空泡反应性系数,初步达到了堆芯的安全设计要求.

基于近似Markov Blanket和动态互信息的特征选择算法

针对大量无关和冗余特征的存在可能降低分类器性能的问题,提出了一种基于近似Markov Blanket和动态互信息的特征选择算法。该算法利用互信息作为特征相关性的度量准则,并在未识别的样本上对互信息进行动态估值,利用近似Markov Blanket原理准确地去除冗余特征,从而获得远小于原始特征规模的特征子集。通过仿真试验证明了该算法的有效性。以支持向量机为分类器,在公共数据集UCI上进行了试验,并与DMIFS和ReliefF算法进行了对比。试验结果证明,该算法选取的特征子集与原始特征子集相比,以远小于原始特征规模的特征子集获得了高于或接近于原始特征集合的分类结果。

莎士比亚与英语词汇(13)

25.birthplace(名词) 该词的意思是“诞生地,出生地”。英语的释义是site of origin;place where somebody is born。Coriolanus(《科里奥兰纳斯》)于大约1608 年完成,1623年用对开本印刷,按创作顺序排列, 大概是莎士比亚的最后一部悲剧。

Nitrogen removal via nitrite from municipal landfill leachate

A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB）, an anoxic/aerobic （A/O） reactor and a sequencing batch reactor （SBR）, was used to treat landfill leachate. During operation, denitrification and methanogenesis took place simultaneously in the first stage UASB, and the effluent chemical oxygen demand （COD） was further removed in the second stage UASB. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor, and ammonia was removed via nitrite in it. Last but not least, the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification. The results over 120 d （60 d for phase I and 60 d for phase II） were as follows： when the total nitrogen （TN） concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L, the shortcut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor. The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%, respectively. The residual ammonia, nitrite and nitrate produced during nitrification in the A/O reactor could be washed out almost completely in SBR. The TN and ammonia nitrogen concentrations of final effluent were about 39 mg/L and 12 mg/L, respectively.

Progress on design and related R&D activities for the water-cooled breeder blanket for CFETR

The water-cooled ceramic breeder (WCCB) blanket is one of the blanket candidates for Chinese fusion engineering testing reactor (CFETR) and is being developed at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). This paper reviews design and evolution of the WCCB blanket for CFETR, and presents a new WCCB blanket design according to the latest CFETR core parameters (major and minor radii are R = 7.2 m and a = 2.2 m, respectively) and missions. This new design is expected to satisfy multiple CFETR operation modes of 0.2, 0.5, 1.0, and 1.5 GW fusion power and achieve tritium self-sufficiency. The feasibility of the updated blanket design is evaluated from the aspects of neutronics and thermo-hydraulics. Furthermore, the research and development (R&D) activities supporting to the WCCB blanket for CFETR are reported, including the design code, the water loop experiments, the pebble bed modeling and experiments, and the components fabrication technology.

Effect of Sodium Ion Concentration on Hydrogen Production from Sucrose by Anaerobic Hydrogen-producing Granular Sludge

This work evaluated the effects of sodium ion concentration, ranging from 0 to 16000mg·L^-1（Na^＋）, on the conversion of sucrose to hydrogen by a high-activity anaerobic hydrogen-producing granular sludge. At the optimum sodium ion concentration [1000-2000mg·L^-1（Na^＋）] for hydrogen production at 37℃, the maximum sucrose degradation rate, the specific hydrogen production yield and the specific hydrogen production rate were 393.6-413.1mg·L^-1.h^-1, 28.04-28.97ml·g^-1, 7.52-7.83ml·g^-1.h^-1, respectively. The specific production yields of propionate, butyrate and valerate decreased with increasing sodium ion concentration, whereas the specific acetate production yield increased, meanwhile the specific production yields of ethanol and caproate were less than 55.3 and 12.6mg·g^-1, respectively. The hybrid fermentation composition gradually developed from acetate, propionate and butyrate to acetate with the increase in sodium ion concentration.

Existence detection of blanket jamming based on fractal characteristics in FRFT domain

This paper addresses the existence detection of blanket jamming based on fractal features in fractional Fourier transform （FRET） domain. Firstly, the existences of fractal features of three typical jamming signals are analyzed, and box dimension and information dimension are employed to describe fractal features quantitatively. Then the differences of fractal characteristics between blanket jamming and white Gaussian noise （WGN） in FRFT domain are described, and a detector to detect the jamming is proposed. At last, simulations are done to verify that the algorithm is effective preferable.

Core and blanket thermal-hydraulic analysis of a molten salt fast reactor based on coupling of OpenMC and OpenFOAM

In the core of a molten salt fast reactor(MSFR),heavy metal fuel and fission products can be dissolved in a molten fluoride salt to form a eutectic mixture that acts as both fuel and coolant.Fission energy is released from the fuel salt and transferred to the second loop by fuel salt circulation.Therefore,the MSFR is characterized by strong interaction between the neutronics and the thermal hydraulics.Moreover,recirculation flow occurs,and nuclear heat is accumulated near the fertile blanket,which significantly affects both the flow and the temperature fields in the core.In this work,to further optimize the conceptual geometric design of the MSFR,three geometries of the core and fertile blanket are proposed,and the thermal-hydraulic characteristics,including the three-dimensional flow and temperature fields of the fuel and fertile salts,are simulated and analyzed using a coupling scheme between the open source codes OpenMC and OpenFOAM.The numerical results indicate that a flatter core temperature distribution can be obtained and the hot spot and flow stagnation zones that appear in the upper and lower parts of the core center near the reflector can be eliminated by curving both the top and bottom walls of the core.Moreover,eight cooling loops with a total flow rate of0.0555 m3 s-1 ensur an acceptable temperature distribusure an acceptable temperature distribution in the fertile blanket.

Treating leachate mixture with anaerobic ammonium oxidation technology

Large amounts of ammonium and a low content of biodegradable chemical oxygen demand（COD） are contained in leachate from aged landfills, together with the effluent containing high concentration of nitric nitrogen after biochemical treatment. Treatment effect of anaerobic ammonium oxidation （anammox） process on the mixture of the leachate and its biochemical effluent was investigated. The results show that the average removal efficiencies of ammonium, nitric nitrogen and total nitrogen are 87.51%, 74.95% and 79.59%, respectively, corresponding to the average ratio of removed nitric nitrogen to ammonium, i.e. 1.14 during the steady phase of anammox activity. The mean removal efficiency of COD is only 24.01% during the experimental period. Thc,dcmand of total phosphorous for the anammox process is unobvious. Especially, the alkalinity and pH value of the effluent are close to those of the inftuent during the steady phase of anammox activity. In addition, it is demonstrated that the status of the anammox bioreactor can be indicated by the alkalinity and pH value during the course of the experiment. The anammox bioreactor has shown potential for nitrogen removal in the leachate mixture. However, COD and total phosphorous in the leachate mixture need further treatment for removal efficiencies of COD and total phosphorous are not good in the anammox bioreactor.

A Study on the Architectural Application of Aerogel

As the building energy saving is more and more important, high-performing insulation like aerogel will be required in buildings to improve their thermal environment and to save building energy. This study conducted the literature survey on the aerogel blanket and presents the architectural application considering its high-insulating property. If aerogel is applied to a building as an envelope insulation, its thickness could be reduced to as half as that of existing insulation such as polystyrene foam board or glassfiber. Currently, aerogel is largely used as a thermal breaker in thermal bridges in buildings. It is still too expensive to be used as a main insulation of whole building envelopes. Thanks to the advantages of aerogel blanket such as low thermal conductivity, broad temperature range for use, excellent water repellent property and fire resistance, easiness of moving and applying, it has much possibility in the respect of its building application.

Considering for the blanket structure scheme of HCCB DEMO

For the solid blanket concept of helium cooled ceramic breeder (HCCB) demonstration fusion power plant (DEMO), a feasible blanket structure with configuration 2×X is proposed as considering relatively low temperature limit of neutron multiplier beryllium pebbles. Based on that, preliminary design for the typical blanket module of HCCB DEMO has been carried out and verified by thermal-hydraulic analysis and structural analysis. Furthermore, the specific relationship of maximum temperature depended on the surface heating of blanket key part first wall (FW) is also analyzed.