分类： 核科学技术 >> 核动力工程技术 提交时间： 2024-02-01
摘要： 贝塔辐射伏特核电池，利用放射性同位素所释放的贝塔粒子来实现电能转化，被广泛视为一项备受期待的替代能源技术。为满足微机电系统（MEMS）的功率需求，研究人员已提出采用三维（3D）结构作为一种潜在的解决方案。在此背景下，本研究引入了一种全新的3D电池设计，基于63Ni-SiC材料构建了一种P+PNN+多沟槽结构。这一结构的独特之处在于，无需在半导体器件的沟槽内表面外延PN结，以降低漏电流和功率损失。通过蒙特卡洛模拟方法，充分考虑了完全耦合的物理模型，我们成功将电子-空穴对产生率（G(x)）扩展到了3D结构中，使得高效设计和开发具有复杂3D结构的贝塔辐射伏特电池成为可能。研究结果表明，相较于传统的平面电池，我们提出的3D电池在最大输出功率密度方面表现卓越，达到了19.74 W/cm2，相应的短路电流、开路电压和转换效率分别为8.57 A/cm2、2.45 V和4.58%。此外，我们还利用COMSOL Multiphysics软件对载流子的传输和收集特性进行了深入分析，为电池输出功率提升机制提供了深刻见解，并对贝塔辐射伏特电池的理想性能与仿真性能之间的差异进行了阐释。本研究为高输出性能的贝塔辐射伏特核电池的设计与优化提供了前瞻性方法，同时也为未来电池器件制造提供了有价值的参考。
分类： 其他 >> 综合 提交时间： 2023-03-28 合作期刊: 《中国科学院院刊》
摘要： 海洋事关国家战略利益，事关全人类共同命运，急需发展全方位、多维度地观测、探测海洋的各类装备。文章简要介绍了核能应用于水下观探测装备供能的2种技术途径及各类热电转换技术，定性归纳了核供能对各类型装备的适用性，分析了其中的核安全相关问题，并建议重点支持放射性同位素制备与分离技术研究与平台建设、个性化特种反应堆研发与共性平台建设、热电转换技术研究及相关核安全问题研究。
分类： 其他 >> 综合 提交时间： 2023-03-19 合作期刊: 《中国科学院院刊》
摘要： 习近平强调，发展是第一要务，人才是第一资源，创新是第一动力。文章从科技发展的历史维度，阐述了创新是第一动力，人才是第一资源的深刻内涵和逻辑外延。深入理解和把握这一重要论断的精神实质，汲取科技发展的历史经验和智慧，对于指导科技创新实践，推进世界科技强国建设具有重要意义和价值。
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-11-29
摘要： 相位漂移现象是干涉测量中普遍存在的问题，对解调结果的准确度带来巨大影响。提出了一种光源混合频率调制的闭环工作点无源控制方法，通过直接高频调制光源的方式从单路干涉信号中提取出相位漂移信号，并利用低频控制信号对光源直接调制的方式予以补偿；通过高频、低频调制信号的配合，解决了单路干涉信号的工作点跟踪问题，以无源控制的方式保证干涉测量系统始终工作在最灵敏的线性区域。测试了光源在不同调制频率下的调制特性，比较了系统开、闭环状态下工作点的变化趋势，无源闭环工作点控制法与相位载波解调算法的对比解调结果表明两种方法解调结果相关度超过 ，证明该方法可行。
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-11-29
摘要： We present an improved digital phase generated carrier (PGC)algorithm based on the synchronous carrier restoration(SCR) method to mitigate the carrier phase delay effects. The most distinguishing feature of this method is that it picks up the carrier signal information (frequency and phase) from the interference signal directly and accomplishes the processing of carrier signal restoration synchronically. In comparison with the traditional one which adopts the initial carrier signal, the total-harmonic-distortions of the SCR method is only 0.091%, lower than the traditional one's 18.38%, and the signal-to-noise-ratio increases 29 dB. Further, we derive the analytic expression of distortion component and verify it by experiments. Thistechnique may be potentially applied in a long distance large-scale distributed fiber-optic interferometer sensors array.
分类： 物理学 >> 核物理学 提交时间： 2017-11-24
摘要： The high power ion source is the key parts of neutral beam injector. Generally speaking, the beam power should matching the extraction voltage for a given accelerator. In order to get higher beam power with lower beam extraction voltage, the beam optics of accelerator was analyzed based on the structure of EAST-NBI tetrode accelerator. The beam optics of a tetrode accelerator and a new designed three-electrode accelerator was analyzed with beam energy of 50 keV. The results shown that, the two types of accelerator can get high beam perveance (4.6μp) with lower beam divergence angle compare to the EAST-NBI accelerator (2.8μp). And the tetrode accelerator can gets lower beam divergence angle compare to the three-electrode accelerator, but the electric field between two electrode is much higher than three-electrode accelerator. The results can help for the ion source design of high power ion source.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-11-02
摘要： An improved algebraic reconstruction technique(ART) with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proved that reconstruction quality dramatically increases with increasing number of projection rays until they are more than 180 for 20×20 grid, and after that point, the number of projection rays has little impact on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration by traditional concentration calculation method, the study in this article also proposed an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly, the capability of this new method is evaluated by appropriate assessment parameters. By using this new approach, the concentration reconstruction accuracy is not only badly improved, but also a suitable parallel-beam arrangement is put forward for sake of high reconstruction accuracy and simplicity of experimental validation. At last, a bimodal structure of combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable for accurate temperature and concentration profiles detection, this feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices.
分类： 生物学 >> 生物工程 提交时间： 2017-09-20
摘要： 维生素K2是一种人体必需维生素，具有促进凝血酶原产生和骨钙素合成等作用，在损伤细胞修复方面也有明显效果。微生物发酵法制备维生素K2具有环境影响小、生物活性高、生产成本低等优点，是维生素K2规模化制备的发展趋势。利用超声波和表面活性剂提高微生物发酵过程中菌体细胞通透性是一种常见的细胞代谢人工调控方法。低功率超声波的空化作用可以在细胞表面瞬间造成微伤，使细胞膜局部破裂从而改变细胞膜的通透性，有利于胞内物质释放或胞外物质进入细胞内。表面活性剂有助于提高营养物质溶解性，降低培养基表面张力，减小菌体表面和培养基的界面阻力，从而促进营养物质和菌体代谢产物的跨膜传输。 本文对实验室保藏的一株产维生素K2黄杆菌（Flavobacterium.sp）Fla-M进行低功率超声波辐照和表面活性剂处理，考察二者在提高细胞渗漏发酵方面的协同作用。首先在500 mL摇瓶中对Fla-M进行表面活性剂（聚氧乙烯油醚POE）添加时间和添加浓度优化，发现在发酵起始阶段添加1%POE效果最佳，发酵结束时生物量为13.4 g/L，胞外维生素K2产量为36.3 mg/L，相比于未添加POE的对照组（生物量7.32 g/L，胞外维生素K2 0.85 mg/L）分别提高了83.5%和41倍，扫描电镜观察发现在添加POE发酵的菌体表面聚集了大量表面活性剂胶团，由于POE与细胞膜磷脂分子结构相似，二者可能相溶形成混合胶束改变了细胞膜结构，进而改善细胞膜的通透性。其次在500 mL摇瓶中对Fla-M进行了超声方式、超声时机、超声功率以及作用时间研究，发现在菌体生长稳定期（发酵第5 d）、120 W 20 KHz条件下，插入式超声98 S（每次3 S，间隔4 S）效果最佳，发酵结束时生物量为11.1 g/L，胞外维生素K2达到50.1 mg/L, 相比于未超声对照组（生物量7.32 g/L，胞外维生素K2 0.85 mg/L），分别提高了51.6%和58倍。透射电镜观察发现超声波处理后尽管细胞膜完整但磷脂双分子层界限模糊，且细胞膜表面有孔状破损结构，可见疑似内容物外渗现象。在上述最优条件下，在500 mL摇瓶中综合运用POE和超声的处理方法，生物量和胞外维生素K2产量在发酵6 d后达到最大值，分别为生物量11.5 g/L，胞外维生素K2 59.7 mg/L，较单独运用POE或超声的方法发酵周期缩短3 d、胞外维生素K2产量分别提高64.4%和19.1%。运用排斥性染料碘化丙啶(PI)对发酵后细胞进行流式细胞仪检测，设001号为阴性对照，即未加荧光载体的未处理菌体的荧光信号；002号为处理的菌体加荧光载体的荧光信号；003号为未处理菌体加荧光载体的荧光信号；004号为阳性对照，即死细胞加荧光载体的荧光信号，阴性对照的001号菌体自发荧光区域以外的面积M1占总面积的比例预设为0，结果显示004号的M1占总面积的比例17.21%>002号M1占总面积的比例8.89%>003号M1占总面积的比例1.21%，说明死菌体的细胞膜通透性>渗漏培养菌体的细胞膜通透性>无渗漏培养菌体的细胞膜通透性，验证了经超声和表面活性剂处理后，菌体细胞膜通透性大幅提高。本研究对发酵法制备维生素K2的产业化开发具有一定的借鉴意义。
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-08-23
摘要： We present systematic first-principles studies of occupancy, diffusion, and segregation of He atoms, as well as underlying evolution mechanism of He clusters in Ta, Re and Os precipitates to help to understand the effect of alloying solutes on He retention and bubble formation. It is found that single He atom prefers tetrahedral (T) site in Ta and basal octahedral (BO) site in Re and Os. Single He atom prefers the diffusion path from one T site to the closest T site in Ta, and the diffusion path from one BO site to the next BO site passing an octahedral site along $\langle$0001$\rangle$ direction in Re and Os. The diffusion of single He atom in Ta, Re and Os is relatively difficult than that in W. He atoms are energetically favorable to segregate at interstitial sites forming He$_{n}$ clusters in Ta, Re and Os, and form close-packed He monolayer structure between (110) planes in Ta. The binding strength of He$_{n}$ cluster in Ta, Re and Os is relatively small than that in W (W>Os>Re>Ta). Compared with interstitial sites, He atoms are more energetically favorable to aggregate in vacancy cluster forming VacmHen. The binding strength order of VacmHen cluster in the systems obeys W>Os>Re>Ta. We thus expect that the presence of Ta and Re may contribute to reduce He retention and bubble formation in W.
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