微波陶瓷介质谐振器优选组合检测法

微波介质陶瓷材料的介电性能主要由3个参数表示:介电常数、介质损耗和谐振频率温度系数.本文优选组合了3种检测介质谐振器方法:短路型介质谐振器轴向的短路界面测定方便准确,用于测量微波介质陶瓷材料的相对介电常数;开路型平行板与介质谐振器无直接接触,用于测量介质损耗系数;自行研制的旋转开放腔,可同时放置多个样品,加快温度系数的测量速度.3个参数采用3种不同测试法,充分应用了不同测试法各自的优势,满足微波介质陶瓷材料介电常数跨度大、介质损耗低、温度系数快速测量的需求,可得到精确、快速的测试效果.     

ADAPTIVE RIGID-PLASTIC MESHLESS GALERKIN METHOD AND ITS APPLICATION IN ANALYSIS OF EXTRUSION PROCESSES

Under the hypothesis of the rigid-plastic material,specific efforts are placed on the deve-lopments of the key simulation techniques of the meshless Galerkin method because of the complexity of the deformation process as well as the generality and atomization of the simulation procedures for non-steady state large deformation plastic processes,therefore,an adaptive rigid meshless Galerkin method is developed. The influence domain control method is used in the least square approximation by dynamic evaluation of the magnitude of the influence domain and the effective control of the amount and the positions of the points in the least square approximation in order to improve approxi-mation precision. The amount of the Gauss integration points in the discrete domain is maintained in a considerable magnitude in order to ensure the integration precision in the discrete domain. The length of the frictional boundary of the plastic deformation process may be getting longer when its deforma-tion is getting severe. Thus,the densities of the boundary points of some places get lower. The adap-tive boundary points setting method is employed to improve the approximation precision of the boundary points and enhance the constraint of the boundary condition by adaptive control of boun-dary point density. Some typical extrusion processes are analyzed,detail simulation results such as the deformation field,velocity field,effective strain field,effective strain rate field,the volume loss curve and load-stroke curve are obtained. The effectiveness of the method developed is demonstrated and the precision of the meshless simulation is proved by overall comparison with the results obtained by using the commercial software deform.     

新型尾缘涡冷-冲击结构流动换热特性分析研究

设计了一种新型尾缘结构。通过采用双重涡冷双重冲击的方法,最大限度地利用冷却气流,提高整个尾缘的换热能力。在优化圆形截面通道结构过程中,试着通过改变通道横截面积来减少压力损失,通过几种方案比较,认为只扩大出口面积效果最佳。     

基于混合FE-SEA法的镁质油底壳隔声数值优化

用混合FE-SEA法分析相同厚度的钢、铝合金和镁合金三种材质油底壳的隔声量,综合考虑轻量化和降噪的要求,提出降噪效率的概念,将其作为评价指标,结果显示镁质油底壳的综合性能最为优越。为了更进一步改善镁质油底壳的隔声效果,对隔声低谷处的模态贡献量进行分析,找出隔声低谷的关键参与模态。通过调取该频率处的速度振型,识别出油底壳上严重振动区域,在此区域内表面添加加强筋,有效地抑制了振动,同时低谷处的隔声也得到明显的改善。     

基于逆向工程技术的天然牙磨损量测量研究

由于天然牙牙冠磨损量微小且形貌复杂,传统的测量方法难以精确获得磨损量。提出采用基于逆向工程技术的天然牙磨损量测量方法。首先通过三维扫描仪获取磨损实验前后的天然牙点云数据,其次采用逆向工程软件Geomagic studio中的最近点迭代ICP(Iterative Closest Point)算法将磨损前后的天然牙点云数据对齐,在此基础上通过3D比较和体积计算,测算出磨损区域的最大磨损高度、平均磨损高度和磨损体积3个磨损特征量。结果表明,该方法能够较为准确地实现天然牙磨损量的测量,同时再现磨损区域的空间几何形状,实现磨损量测量过程的数字化、定量化和可视化。     

AltBOC navigation signal quality assessment and measurement

In order to ensure that Chinese BeiDou satellite navigation system runs smoothly,the assessment of signal quality has become a significant task.Alternative binary offset carrier （AltBOC） is BeiDou B2 frequency signal.The acquisition of BeiDou signal is processed in off-line mode and the evaluation is performed by taking signal power spectrum,eye diagram,constellation,correlation,loss and s-curve deviation on AltBOC as signal quality evaluation parameters.The results illustrate that the new system signal,namely AltBOC signal,has the best performance in code tracking precision,anti-jamming and anti-multipath.     

Two types of a passive safety containment for a near future BWR with active and passive safety systems

The paper presents two types of a passive safety containment for a near future BWR. They are named Mark S and Mark X containment. One of their common merits is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. The PCV pressure can be moderated within the design pressure. Another merit is the capability to submerge the PCV and the RPV above the core level. The third merit is robustness against external events such as a large commercial airplane crash. Both the containments have a passive cooling core catcher that has radial cooling channels. The Mark S containment is made of reinforced concrete and applicable to a large power BWR up to 1830 MWe. The Mark X containment has the steel secondary containment and can be cooled by natural circulation of outside air. It can accommodate a medium power BWR up to 1380 MWe. In both cases the plants have active and passive safety systems constituting in-depth hybrid safety (IDHS). The IDHS provides not only hardware diversity between active and passive safety systems but also more importantly diversity of the ultimate heat sinks between the atmosphere and the sea water. Although the plant concept discussed in the paper uses well-established technology, plant performance including economy is innovatively and evolutionally improved. Nothing is new in the hardware but everything is new in the performance.     

考虑弹体中涡流影响的引信感应装定能量和信息传输通道模型

针对引信电磁感应装定中能量和信息传输通道建模时,忽略弹体中涡流影响,模型不准确的问题,基于分离式变压器能量与信息同步传输理论和涡流理论,提出采用分离式变压器的互感模型耦合涡流回路,描述通道传输特性的方法.通过对传输通道等效电路分析,推导出系统最佳工作条件和涡流损耗功率,并探讨了漏感补偿问题.最后针对两种不同型号引信,实验对比弹体中有无涡流时次级回路输出电压的差异,结果表明该模型能较准确描述装定过程中能量和信息的传输特性.     

Venturi tube application in high power test of the SRF module

In the superconducting RF module, the dissipation power of the niobium cavity is an important parameter. In the Superconducting radio frequency (SRF) module’s acceptance test at Shanghai Synchrotron Radiation Facility (SSRF), the Venturi tube is used to measure the quality factor of SRF cavity at 4.2 K. During the test, the venturi tube is be calibrated by increasing heat load with internal heater. In this paper, the horizontal test principle and venturi effect are briefly introduced. The authors find out a...     

A feasibility assessment of the use of nanofluids to enhance the in-vessel retention capability in light-water reactors

Nanofluids, colloidal dispersions of nanoparticles, exhibit a substantially higher critical heat flux (CHF) compared to water. As such, they could be used to enhance the in-vessel retention (IVR) capability in the severe accident management strategy implemented by certain light-water reactors. It is envisioned that, at normal operating conditions, the nanofluid would be stored in dedicated storage tanks, which, upon actuation, would discharge into the reactor cavity through injection lines. The design of the injection system was explored with risk-informed analyses and computational fluid dynamics. It was determined that the system has a reasonably low failure probability, and that, once injected, the nanofluid would be delivered effectively to the reactor vessel surface within seconds. It was also shown analytically that the increase in decay power removal through the vessel using a nanofluid is about 40%, which could be exploited to provide a higher IVR safety margin or, for a given margin, to enable IVR at higher core power. Finally, the colloidal stability of a candidate alumina-based nanofluid in an IVR environment was experimentally investigated, and it was found that this nanofluid would be stable against dilution, exposure to gamma radiation, and mixing with boric acid and lithium hydroxide, but not tri-sodium phosphate.