�۱�ҳ�ʵ��װ��STARDUSTʧ����¹ʵ���ֵģ��

建立了聚变灰尘实验装置STARDUST相应的数值计算模型,用数值模拟对失真空事故(LOVA)实验物理过程进行了重现。模拟计算了该实验装置在不同位置处的破口产生LOVA后的速度场发展过程。给出腔室内关键位置速度变化曲线,并与实验所测量到的相应点的速度变化曲线进行了比较。结果表明应用计算流体力学所进行的数值模拟计算达到了对实验重现的目的,其中RNG k-ε湍流模型能够对发生失真空事故下的气体流动状态进行较好的模拟,而且可以较好地预测失真空事故的风险。     

高压氢气输运装置物理爆炸状态场特征及灾害效应研究

 由于输运装置突然失效而引发的高压氢气喷射,能够在流场中造成超压和足以引发爆炸的扩散。运用数值计算方法,建立可用于计算的物理和数学模型对发生泄漏后有、无障碍物两种情况下的外部流场进行分析,可得到外部流场中的气体泄漏压力和浓度的分布等值线图。从计算结果可以得出氢气发生爆炸事故后的危险区域,障碍物对氢气的喷射泄漏以及爆炸所产生的影响,从而可为预防和处理氢气爆炸事故提供参考依据。     

ITER 失真空事故下铍灰尘分布的数值研究

采用计算流体动力学方法,通过对ITER 装置的设计结构进行合理简化,建立了ITER 装置的三维计算模型,研究了失真空事故下铍灰尘在ITER 装置内的迁移进程,得到了铍灰尘在ITER 装置内的分布情况。通过分析铍灰尘在不同截面高度、不同时刻的分布特性,得到以下结论：随着高度增加,截面位置上的铍灰尘体积分数呈下降趋势;随着时间推移,截面位置上的铍灰尘体积分数呈上升趋势。     

ITER ʧ����¹�����ҳ��ֲ�����ֵ�о�

采用计算流体动力学方法,通过对ITER装置的设计结构进行合理简化,建立了ITER装置的三维计算模型,研究了失真空事故下铍灰尘在 ITER 装置内的迁移进程,得到了铍灰尘在 ITER 装置内的分布情况。通过分析铍灰尘在不同截面高度、不同时刻的分布特性,得到以下结论：随着高度增加,截面位置上的铍灰尘体积分数呈下降趋势;随着时间推移,截面位置上的铍灰尘体积分数呈上升趋势。     

基于栅控横向PNP双极晶体管的氢氛围中辐照损伤机制

为了研究氢气与辐射感生产物之间的作用关系,以栅控横向PNP双极晶体管为研究对象,分别开展了氢气氛围中浸泡后的辐照实验和辐照后氢气氛围中退火实验,结果表明:氢气进入双极晶体管后会使其辐照损伤增强,并且未浸泡器件辐照后在氢气中退火也会使晶体管辐射损伤增强.基于栅扫描法分离的辐射感生产物结果表明,氢气进入晶体管会使得界面陷阱增多,氧化物陷阱电荷减少,主要原因是氢气进入氧化层会与辐射产生的氧化物陷阱电荷发生反应,产生氢离子,从而使界面陷阱增多.基于该反应机理,建立了包含氢气反应和氢离子产生机制的低剂量率辐照损伤增强效应数值模型,模型仿真得到的界面陷阱及氧化物陷阱电荷面密度数量级和变化趋势均与实验结果一致,进一步验证了氢气在双极器件中辐照反应机理的正确性,为双极器件辐照损伤机制研究和在氢氛围中浸泡作为低剂量率辐射损伤增强效应加速评估方法的建立提供了参考和理论支撑.     

HTc SQUID磁强计用无磁液氮玻璃钢杜瓦的真空性能研究

提出当对无磁液氮玻璃钢杜瓦抽真空时 ,向无磁液氮玻璃钢杜瓦的真空夹层充注微量的二氧化碳气体 ,所充入的二氧化碳气体就会和玻璃钢表面的氢气、一氧化碳、二氧化碳、甲烷等气体发生协同交换反应 ,使玻璃钢表面的氢气、一氧化碳、二氧化碳、甲烷等气体的脱附速度大大增加 ,减少了抽真空时间。由于无磁液氮玻璃钢杜瓦内使用的活性炭吸附剂对二氧化碳的吸附性能远远大于对玻璃钢材料所放出的氢气、一氧化碳和甲烷等主要气体的吸附性能 ,从而使得抽好真空的无磁液氮玻璃钢杜瓦的真空保持时间大大增加 ,延长了无磁液氮玻璃钢杜瓦的使用寿命     

生物油轻质馏分加氢试验研究

本文基于分子蒸馏设备对流化床快速热解试验装置所产生物油进行预分离,得到的轻质馏分在固定床加氢微反应装置上进行Ru/γ-Al2O3催化的加氢精制研究,分析了反应温度(60～140℃)、氢气压力(常压～3MPa)和进料速率(1.5～4.5ml/h)对反应产物组分分布的影响规律.研究结果表明,通过加氢精制后,生物油轻质馏分中不饱合化合物在大于120℃的反应条件下得到完全转化;醇类化合物的种类有所增多.     

基于声谐振驱动的氢气流量检测系统设计与实现

氢气在空气中的爆炸极限浓度较低,当前电化学传感器氢气检测中容易受到电磁干扰引起爆炸,安全系数低;设计并实现了一种基于声谐振频率驱动的氢气流量检测系统设计方法,通过检测不同浓度的氢气通过传感器后引起的传感器谐振频率的变化反应氢气的浓度变化,系统基于S3C2410模块设计,设计了外围的信号调理电路,对芯片进行了Linux系统移植,安全性和准确性都有很大提高;最后进行仿真实验,实验工具包括传感器与探头,芯片搭建的硬件电路,USB数据采集卡;型号分别为1%,2.54%,3.05%,4.1%的经过国家标准检验的氢气,型号为0.513%的一氧化碳,型号为100%的二氧化碳与氧气;实验结果表明,系统能在10 s内对超浓度的氢气流量监控报警,误差在小于0.015,不同的交叉气体下系统的氢气流量检测准确度高达98%,具有很强的实用性。     

氢化物发生原子吸收测定岩石中微量锡——几种氢化物发生方法的比较

氢化物发生原子吸收测定微量砷,锑、铋、硒、碲和锡的技术中,氢化物发生装置直接关系到被测元素的灵敏度和重现性,人们仍在继续探讨。人工注入硼氢化物电磁搅拌之后,相继出现了收集氢化物的装置,用反应中产生的氢气搅拌溶液的装置,以及自动化装置。     

4H-SiC同质外延生长Grove模型研究

本文通过对4H-SiC同质外延化学反应和生长条件的分析,建立了4H-SiC同质外延生长的Grove模型,并结合实验结果进行了分析和验证.通过理论分析和实验验证,得到了外延中氢气载气流量和生长温度对4H-SiC同质外延生长速率的影响.研究表明:外延生长速率在衬底直径上为碗型分布,中心的生长速率略低于边缘的生长速率;随着载气流量的增大,生长速率由输运控制转变为反应速率控制,生长速率先增大而后逐渐降低;载气流量的增加,会使高温区会发生漂移,生长速率的理论值和实验出现一定的偏移;随着外延生长温度的升高,化学反应速率和气相转移系数都会增大,提高了外延速率;温度对外延反应速率的影响远大于对生长质量输运的影响,当温度过分升高后,外延生长会进入质量控制区;但过高的生长温度导致源气体在生长区边缘发生反应,生成固体粒子,使实际参与外延生长的粒子数减少,降低了生长速率,且固体粒子会有一定的概率落在外延层上,严重影响外延层的质量.通过调节氢气流量,衬底旋转速度和生长温度,可以有效的控制外延的生长速度和厚度的均匀性.     

Maximal design basis accident of fusion neutron source DEMO-TIN

When analyzing the safety of nuclear (including fusion) facilities, the maximal design basis accident at which the largest release of activity is expected must certainly be considered. Such an accident is usually the failure of cooling systems of the most thermally stressed components of a reactor (for a fusion facility, it is the divertor or the first wall). The analysis of safety of the ITER reactor and fusion power facilities (including hybrid fission–fusion facilities) shows that the initial event of such a design basis accident is a large-scale break of a pipe in the cooling system of divertor or the first wall outside the vacuum vessel of the facility. The greatest concern is caused by the possibility of hydrogen formation and the inrush of air into the vacuum chamber (VC) with the formation of a detonating mixture and a subsequent detonation explosion. To prevent such an explosion, the emergency forced termination of the fusion reaction, the mounting of shutoff valves in the cooling systems of the divertor and the first wall or blanket for reducing to a minimum the amount of water and air rushing into the VC, the injection of nitrogen or inert gas into the VC for decreasing the hydrogen and oxygen concentration, and other measures are recommended. Owing to a continuous feed-out of the molten-salt fuel mixture from the DEMO-TIN blanket with the removal period of 10 days, the radioactivity release at the accident will mainly be determined by tritium (up to 360 PBq). The activity of fission products in the facility will be up to 50 PBq.     

Multiple component analysis of cigarette smoke using THz spectroscopy,comparison with standard chemical analytical methods

Terahertz time domain spectroscopy and photomixing have been used alongside one another for the detection and the quantification of small polar species in mainstream cigarette smoke. The broadband submillimeter source used in time domain spectroscopy allowed a rapid and simultaneous detection of several pure rotational transitions of hydrogen cyanide (HCN) and carbon monoxide (CO) in realistic conditions of pressure and temperature. The spectral purity of the continuous wave terahertz source produced by photomixing, permitted the concentrations of these molecules to be measured at pressures of tens of hPa. Moreover, at lower pressure, traces of formaldehyde (H₂CO) have been unambiguously identified at frequencies above 1 THz. A comparison with chemical analytical methods has been completed for each molecule highlighting the advantages of the direct measurement by THz spectroscopy. PACS 82.80.-d; 33.20.Bx; 39.30.+w     

超临界水冷堆中子能谱计算及安全性分析

超临界水堆是国际第Ⅳ代核能系统论坛推荐的六种第Ⅳ代核电反应堆堆型之一,与现有的轻水堆相比,具有热效率高、系统结构简单、造价低等优点。建立了MCNP程序下的超临界水堆堆芯物理计算模型,解决了燃料组件几何结构过于复杂精细难以建模的技术难题;考虑了堆芯轴向冷却剂密度的不均匀分布,计算并分析各区域的中子能谱分布;对失水事故下的超临界水冷堆安全性进行了分析,研究了不同区域冷却剂丢失程度对反应性及有效增殖系数的影响,表明所设计堆型具有较高的安全性;分析处理失水事故的应对措施,验证了使用注入硼水措施处理超临界水冷堆失水事故的可行性。     

自悬浮定向流技术中铜纳米微粒的粒度控制研究

 采用自悬浮定向流技术制备了金属铜纳米微粒，根据TEM的行貌像对样品平均粒度进行标定，并结合样品制备的条件对制备工艺进行了研究。结果表明，自悬浮定向流技术可以方便地制备出不同粒度的金属铜纳米微粒，微粒平均粒径随熔球温度的降低而减小，随冷却气体流速的增大而减小；在1 200℃下微粒平均粒径随惰性气体压强的增大而减小，而在1 300℃时惰性气体压强对微粒平均粒径的影响不再具有规律性。     

Surface structure and catalytic activity of rapidly quenched amorphous iron based alloys: I. Effect of the cooling rate

Fe₈₂B₁₈ amorphous ribbon prepared by the rapid quenching method at different cooling rates has been characterized by XPS, UPS, DSC, potentiodynamic method, contact angle measurements and hydrogen TPD. Simultaneously, its catalytic activity and selectivity have been tested in the CO + H₂ reaction. By measuring the depth profile it has been established that at low cooling rate the dull side of the ribbon is more porous and deeply oxidized as well as depleted in boron. On the other hand, the shiny side at low cooling rate is covered by a compact layer of segregated boron. The difference between the two sides largely diminished as the cooling rate increases. Owing to the porous iron oxide surface on the dull side at low cooling rate accessible metallic iron sites in a large amount are present which results in the high catalytic activity in the CO+H₂ reaction. This is supported by potentiodynamic measurements being characteristic of the metal sites. Since the nature of the iron atoms is the same as the cooling rate increases there is no change in the selectivity, only the rate decreases. The selectivity changes can be interpreted by the hydrogen available on the surface determined by hydrogen TPD measurements.     

液氢加注系统中过滤器漏热故障仿真与分析

液氢管道输送需要在极低温度下进行,需要较高的保温措施,而且出现漏热故障的时候将十分危险。发生漏热后的液氢会迅速产生气液两相流,其对加注系统中的器件造成很大的冲击与危害,造成加注系统损坏等事故。因此,对液氢加注系统进行仿真研究有着重要的作用。而过滤器漏热的影响大约是管道漏热的三倍,所以研究过滤器漏热更具有防范风险的指导意义。本文依据AMEsim工程仿真软件,对液氢加注系统进行建模与仿真,并置入过滤器故障仿真进行对比与分析。     

HL-1装置中的等离子体与器壁相互作用

本文对HL-1装置欧姆加热放电时,等离子体—器壁相互作用进行了实验研究。质谱分析定性地指出,主要气相杂质H_2O来自零级表面化学反应,CH_4来自多步骤合成表面化学反应,CO(CO_2)则来自碰撞表面化学反应。收集探针的表面分析显示出,Mo,Cr和Ni等为主要的重杂质;蒙特卡罗模拟分析给出了氢粒子注入硅探针的特征深度和其动力温度的拟合直线关系式。     

Hydrogen-induced low temperature CO displacement from the Pt(111) surface

A new low temperature displacement mechanism for CO on the Pt(111) surface has been observed in the presence of high pressures of hydrogen (0.001 to 0.1 Torr H₂). Temperature-programmed fluorescence yield near-edge spectroscopy (TP FYNES) was used to continuously monitor the CO coverage as a function of temperature both with and without hydrogen. For hydrogen pressures above 0.01 Torr, removal of CO begins at 130 K (E_d = 10.6 kcal/mol) instead of near the desorption temperature of 400 K (E_d = 26 kcal/mol). The large decrease in CO desorption energy appears to be caused by substantial repulsive interactions in the compressed monolayer induced by coadsorbed hydrogen. The new low temperature CO desorption channel appears to be caused by displacement of the compressed CO adlayer by coadsorbed hydrogen. In addition, the desorption activation energy for the main desorption channel of CO near 400 K is lowered by ~ 1 kcal/mol for hydrogen pressures in the 0.001 to 0.1 Torr range. These new results clearly emphasize the importance of in-situ methods capable of performing kinetic experiments at high pressures on well characterized adsorbed monolayers on single crystal surfaces. High coverages of coadsorbed hydrogen resulting from substantial overpressures may substantially modify desorption activation energies and thus coverages and kinetic pathways available even for strongly chemisorbed species. These phenomena may play an important role in surface reactions which occur at high pressure.     

Radioactive contamination of the atmosphere of Cairo,Egypt, from the Fukushima Dai-ichi nuclear plant accident

Radioactive contamination in air dust particles of Cairo atmosphere from the Fukushima accident was detected by the gamma-ray spectroscopy technique. Analysis of the spectra obtained by using an High-Purity Germanium detector showed that there were some traces of ¹³¹I and ^{134, 137}Cs. Estimate and study of concentration of those radionuclides were done over a period of about 5 months after the accident. Comparison with corresponding results in different countries all over the world has been performed.