改进天牛须算法对滑翔炸弹控制器的优化设计

对于采用BT T控制策略的滑翔炸弹这一复杂非线性系统,经过线性化处理后运用分通道设计的思路,来分别对俯仰偏航双通道进行设计.首先描述了其动力学模型,在对该模型分析的基础上,提出了添加混沌扰动的改进天牛须搜索算法,在每次迭代过程中对步长进行了自适应的动态调整,从而设计了基于此算法优化的LQR控制器.经Simulink仿真后对结果进行分析,改进优化算法其优化结果可以更好的跳出局部最优点,且在不同马赫数下设计的控制器都可以较好的满足系统的输出要求,同时也克服了以往经验试凑参数的非通用弊端,从而更好的满足在线调节的要求.     

超临界水冷堆双排燃料组件子通道分析

研究基于Cobra-IV程序,开发了适用于超临界水冷堆燃料组件分析的子通道程序.针对超临界水冷堆慢谱双排组件,进行了稳态计算,获取了相关组件热工水力参数.在此基础上,针对单一通道进行了瞬态计算,分析了燃料棒线功率变化和冷却剂流量变化条件下,超临界水冷堆燃料组件的流动和传热的动态响应,为超临界水冷堆组件的优化设计提供了参考.     

均匀加热全长棒束过冷沸腾工况子通道参数场计算分析

采用壁面热分配模型对PSBT基准题中的5×5均匀加热全长棒束过冷沸腾传热进行了数值模拟研究，分析了均匀加热全长棒束通道中不同子通道和加热元件表面参数沿轴向的发展过程和径向的分布特性。研究发现，角通道和边通道是弱对流区域，其质量流速低于棒束平均值，但由于冷棒功率偏低，消除了流动不均衡性对传热效果的影响。在棒束径向方向，不同位置子通道间参数场存在差异，这是由于位于搅混格架横向导流对角方向的通道具有更有效的通道间对流效果，其传热效果更好。这种流动特性引起的参数差异在角通道中尤为显著。热棒表面过热度明显高于冷棒过热度，且位于非搅混格架横向导流方向的热棒具有更高的壁面过热度。     

CHF Experiments under Steady-State and Transient Conditions for Tight Lattice Core with Non-Uniform Axial Power Distribution

Abstract

Steady-state and transient critical heat flux (CHF) experiments were performed using triangular pitched 7-rod assemblies with non-uniform axial power distributions under the maximum pressure of 15.5 MPa. The onset of steady-state CHF was predicted within the uncertainty of 10% with the KfK correlation using the local flow conditions calculated by the subchannel analysis code COBRA-IV-T. On the other hand, various mechanistic CHF models did not agree with the steady-state CHF data. The transient CHFs under the conditions of flow reduction, power increase or flow and power simultaneous variation were predicted with the quasi-steady-state method within approximately the same uncertainty as the steady-state CHF experiments. The predictive capability did not depend on the transient speed within 30%/s of the flow reduction rate and within 120%/s of the power increase rate. It was also revealed that there exists large CHF margins under the thermal hydraulic conditions simulating the locked rotor accident and the control rod cluster ejection accident of the double-flat-core type high conversion pressurized water reactor (HCPWR).     

多子频带/子信道关联跳频扩频通信技术

技术的发展和个人通信量需求的增长,使得电磁频谱资源日益紧缺,成为当今无线通信技术发展的瓶颈。分析了在信道存在加性白噪声和多址干扰的条件下,频带细化对提高频谱利用率的作用。指出传统频分复用方式和扩频通信方式下频谱利用率不高的根本原因,提出了一种提高频谱利用率的多子频带/多子信道关联跳频通信技术。使用该技术可极大地提高通信频谱利用率,同时可提高通信的保密性。     

Interference management for rate-constrained moving relay node in a heterogeneous network

Cooperative communication via a moving relay node （MRN） helps resolve both the poor quality of service （QoS） and limited battery-capacity problems of cell-edge vehicle user equipment （VUE）. This paper investigates the performance of MRNs in a heterogeneous network （HetNet）. MRNs as well as other small cells are expected to coexist in a complex manner. In such a HetNet, the inter-cell interference may degrade the expected improvement of MRNs, especially at the cell-edge. In this paper, we investigate the impact of intercell interference on the performance of MRNs. To alleviate this impact, we first formulated a general optimization problem for which it is intractable to find a global optimal solution. To have a practical solution with low computational complexity, we used a practical interference management algorithm that aimed to ensure that every MRN achieved its required minimum-rate while maximizing total network throughput. In the simulations, the proposed algorithm was observed to improve both the QoS and fairness of MRNs. Numerical results demonstrate that the proposed algorithm can offer an efficient trade-off between the performance of both the victim MRNs and aggressing femtocells.     

Steady-state thermal-hydraulic analysis of SCWR assembly

Among the six gen-IV reactor concepts recommended by the gen-IV international forum (GIF), supercritical water-cooled reactor (SCWR), the only reactor with water as coolant, achieves a high thermal efficiency and, subsequently, has economic advantages over the existing reactors due to its high outlet temperature. A thermal-hydraulic analysis of the SCWR assembly is performed in this paper using the modified COBRA-IV code. Two approaches to reduce the hot channel factor are investigated: decreasing the moderator mass flow and increasing the thermal resistance between moderator channel and its adjacent sub-channels. It is shown that heat transfer deterioration cannot be avoided in SCWR fuel assembly. It is, therefore, highly required to calculate the cladding temperature accurately and to preserve the fuel rod cladding integrity under heat transfer deterioration conditions. __________ Translated from Nuclear Power Engineering, 2007, 28(5): 18–21, 58 [译自: 核动力工程]     

快堆全堆芯热工流体子通道并行模拟技术研究

采用简化堆芯模型的传统子通道模拟计算结果难以精确反映堆芯的真实运行状况,利用高性能计算技术进行全堆芯精确到每个真实流道的子通道模拟计算成为研究热点。本文抽象描述了快堆堆芯的基础几何结构,在此基础上提出了一种全堆芯子通道建模方法和一种自适应的并行任务划分方法。设计了广度优先划分算法和层次划分算法,实现了全堆芯子通道任意个数求解域的划分,自适应地映射到不同个数的计算核上,从而可利用PC、集群、超算等不同规模的计算资源开展全堆并行模拟。使用针对快堆模拟修改后的子通道模拟软件CTF进行验证,证明了建模方法对于快堆子通道模拟是有效的。基于本文方法在曙光先进计算服务平台上使用两种不同网格规模的算例进行了测试,两组测试最低并行效率在33.02%以上,证明了本文方法的有效性和可用性。