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1.
与安全裕量有关的研究一直是反应堆安全设计与安全分析的重点和难点问题。本文针对池式示范快堆CFR600的设计特点,对主热传输系统中的重要现象进行了分析,并建立了最佳估算模型,基于Wilks方法对CFR600一回路主管道断裂事故进行了不确定性量化计算。最佳估算分析结果表明,CFR600在一回路主管道断裂事故下,包壳最高温度95%/95%上限为851?6 ℃,相较于保守分析结果具有约91?8 ℃裕量,低于包壳破损验收准则。  相似文献   
2.
Air pollution is one of the major concerns considering detriments to human health. This type of pollution leads to several health problems for humans, such as asthma, heart issues, skin diseases, bronchitis, lung cancer, and throat and eye infections. Air pollution also poses serious issues to the planet. Pollution from the vehicle industry is the cause of greenhouse effect and CO2 emissions. Thus, real-time monitoring of air pollution in these areas will help local authorities to analyze the current situation of the city and take necessary actions. The monitoring process has become efficient and dynamic with the advancement of the Internet of things and wireless sensor networks. Localization is the main issue in WSNs; if the sensor node location is unknown, then coverage and power and routing are not optimal. This study concentrates on localization-based air pollution prediction systems for real-time monitoring of smart cities. These systems comprise two phases considering the prediction as heavy or light traffic area using the Gaussian support vector machine algorithm based on the air pollutants, such as PM2.5 particulate matter, PM10, nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and sulfur dioxide (SO2). The sensor nodes are localized on the basis of the predicted area using the meta-heuristic algorithms called fast correlation-based elephant herding optimization. The dataset is divided into training and testing parts based on 10 cross-validations. The evaluation on predicting the air pollutant for localization is performed with the training dataset. Mean error prediction in localizing nodes is 9.83 which is lesser than existing solutions and accuracy is 95%.  相似文献   
3.
Segmentation of vessel in retinal fundus images is a primary step for the clinical identification for specific eye diseases. Effective diagnosis of vascular pathologies from angiographic images is thus a vital aspect and generally depends on segmentation of vascular structure. Although various approaches for retinal vessel segmentation are extensively utilized, however, the responses are lower at vessel's edges. The curvelet transform signifies edges better than wavelets, and hence convenient for multiscale edge enhancement. The bilateral filter is a nonlinear filter that is capable of providing effective smoothing while preserving strong edges. Fast bilateral filter is an advanced version of bilateral filter that regulates the contrast while preserving the edges. Therefore, in this paper a fusion algorithm is recommended by fusing fast bilateral filter that can effectively preserve the edge details and curvelet transform that has better capability to detect the edge direction feature and better investigation and tracking of significant characteristics of the image. Afterwards C mean thresholding is used for the extraction of vessel. The recommended fusion approach is assessed on DRIVE dataset. Experimental results illustrate that the fusion algorithm preserved the advantages of the both and provides better result. The results demonstrate that the recommended method outperforms the traditional approaches.  相似文献   
4.
The development of novel redox-active polymers for sustainable sodium ion batteries (SIBs) has captured growing attention, but battery performance has been significantly limited by poor reversible specific capacities, where the majority of aromatic C6-benzene linkages are redox inactive. Here, a simple, yet efficient approach to improve sodium (Na) storage on these C6-benzene rings within a porous polymeric framework by rationally regulating their steric hindrance is reported. Decreasing intrinsic hindrance affords a significant improvement in redox reaction kinetics within the porous architecture, thereby facilitating the acceptance of Na ions on these functionalized benzene rings and boosting the SIB performance. As a result, the modulate porous framework exhibits an exceptional battery capacity of 376 mAh g?1 after 1000 cycles at 1.0 A g?1, which is ≈1.5 times larger than that of the pristine framework. Furthermore, the performance can reach as high as 510 mAh g?1 at 0.1 A g?1, comparable to that of the best-performing polymeric electrodes. The simple modulation approach not only enables Na storage modulation on functionalized C6-benzene rings, but also simultaneously provides a means to extend the understanding of the structure-property relationship and facilitate new possibilities for organic SIBs.  相似文献   
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6.
材料是核聚变堆应用的瓶颈问题之一。本文根据核聚变堆领域的要求使用低活化材料以及考虑到未来工程应用需要降低成本,选用低活化、低成本的Fe、Cr、V元素,依据最小吉布斯自由能准则设计出非等原子比Fe36.41Cr28.06V35.53单相中熵合金。采用真空熔炼的方法制备出该合金,并对其进行适当的热机处理。发现非等比Fe36.41Cr28.06V35.53合金在不同热机处理过程中没有发生相变,均为单相bcc固溶体,说明该合金相结构非常稳定。同时也与依据最小吉布斯自由能准则设计的结果吻合得非常好。Fe36.41Cr28.06V35.53合金的硬度高于传统耐热合金,在不同热机加工状态下合金的压缩塑性均大于50%,实现了强度和塑性的良好配合。在压缩变形过程中,由于偏析元素与位错的相互作用,合金的压缩应力—应变曲线出现锯齿流变行为。对Fe36.41Cr28.06V35.53合金进行了详细的微观组织表征,解释了该合金性能优异的微观机制。  相似文献   
7.
The phase diagram of ZrO2–CaO–TiO2 system was essential for the development of photocatalytic materials and refractory materials. In this work, the ZrO2–CaO–TiO2 system was accessed by using the CALPHAD method. The substitutional solution models were used to describe liquid and solid solution phases, the sub-lattice models were used to describe ternary compounds, and then the thermodynamic parameters were obtained by the least square method combined with literature experiment results. The acquired thermodynamic parameters were used to calculate the isothermal sections of the ZrO2–CaO–TiO2 system at 1473 and 1673 K. There existed a good agreement between experimental and predicted phase relationships, the experimental points which were inconsistent with calculated results may be attributed to experimental errors and the sluggish kinetics of cations for ZrO2-based materials. In order to further verify the validity of the database, the thermodynamic parameters were also used to simulate the thermodynamic properties (specific heat capacity, enthalpy, and entropy) of CaZrTi2O7 within 5% errors. Good consistency demonstrated that the present thermodynamic database was self-consistent and credible.  相似文献   
8.
The hexagonal to orthorhombic (HO) transformation from β-Ni3Sn2 (hexagonal) phase to α’-Ni3Sn2 (orthorhombic) phase was confirmed in directionally solidified Sn–Ni peritectic alloys. It is shown that the remelting/resolidification process which is caused by both the temperature gradient zone melting (TGZM) and Gibbs?Thomson (G?T) effects can take place on secondary dendrites. Besides, the intersection angle between the primary dendrite stem and secondary branch (θ) is found to increase from π/3 to π/2 as the solidification proceeds. This is the morphological feature of the HO transformation, which can change the diffusion distance of the remelting/ resolidification process. Thus, a diffusion-based analytical model is established to describe this process through the specific surface area (SV) of dendrites. The theoretical prediction demonstrates that the remelting/resolidification process is restricted when the HO transformation occurs during peritectic solidification. In addition, the slope of the prediction curves is changed, indicating the variation of the local remelting/resolidification rates.  相似文献   
9.
电动出租车作为快速充电及路-电耦合网络的主要参与者,其连续行驶-充电行为严重影响了路-电耦合网络的运行状态,为此提出了基于路-电耦合网络的电动出租车快速充电引导及其定价策略。首先,提出了电动出租车在路-电耦合网络下交通流-能量流-信息流的交互框架;然后,提出了交通网的信息动态更新策略,建立了单辆电动出租车模型用于模拟电动出租车的连续行驶-充电状态切换行为;在此基础上,提出了路径规划与交通网信息更新同周期的动态导航及考虑下一寻客点的选站决策方法;最后,根据站内负荷和选站负荷进行虚拟负荷预测,提出了基于虚拟负荷和利用率均衡的充电站定价策略。算例仿真结果表明,所提方法能够均衡充电站负荷,缓解交通网的拥堵状况,提高电动出租车的运营收入。  相似文献   
10.
针对卷积神经网络应用于图像分类任务时需要大量有标签数据的问题,提出一种融合卷积神经网络和聚类分析的无监督分类模型,将无监督算法引入深度学习,并将该模型应用到图像分类领域,来弥补现有分类方式的不足。首先对经典卷积神经网络AlexNet从网络结构和模型训练两个方面进行优化;然后利用改进后的自适应快速峰值聚类算法指导聚类过程,该模型在学习整个网络参数的同时对卷积输出的特征进行聚类,这两个过程迭代进行,以达到对图像进行无监督分类的目的;为了验证所提出的无监督图像分类模型的可行性和有效性,选用了四个常用于图像分类领域的数据集分别进行了分类实验,并将结果与近年来在图像无监督分类任务上表现相对优越的几种算法进行了横向对比。结果表明提出的无监督分类模型在不同数据集上均较现有的几种无监督方法有着更出色的表现。  相似文献   
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