任意结构阵列基于高阶累积量的信号频率和二维角联合估计算法

提出了一种基于高阶累积量的信号频率和二维角估计算法。假设阵列中存在3个特性完全一致的阵元,此时使用高阶累积量实现的阵列虚拟展宽相当于存在两个和实际阵列相同的虚拟平移阵列,因而在其它阵元位置和响应特性未知的情况下也能实现空间信号频率和二维角估计。推导了使用PRO-ESPRIT算法实现联合估计的过程,并给出了相应的信号配对方法,计算机模拟结果证实了该算法的有效性。     

项目投资时机及投资概率分析

针对实物期权理论中存在的不足,运用鞅理论分析研究了市场环境下的确定性和不确定性因素对实物资产项目投资决策的影响.首先,通过鞅方法建立了反映投资时机和投资回报临界值之间关系的投资时机模型;然后,使用测度变换评价了项目投资能够被实施的可能性.研究结果表明确定性因素对投资时机和投资回报临界值具有相反作用的影响,不确定性因素则均具有正向作用的影响,且在确定性因素取值较小情况下,不确定性对投资却具有促进作用.     

表征高温性能的沥青纯粘性稠度

利用自行研发的沥青稠度测试仪,对沥青高温流动和粘弹特性进行分析可知,粘性成分是沥青抵抗变形的关键.为此引入了0.1 s-1剪变率时的纯粘性稠度,并提出了计算方法.将高温时0.1 s-1纯粘性稠度与沥青常规高温指标和沥青混合料动稳定度进行了比较分析,结果表明:高温时0.1 s-1纯粘性稠度克服了常规指标不适宜评价改性沥青的缺点,适合作为沥青高温性能新指标.最后,分析并推荐了沥青高温0.1 s-1纯粘性稠度标准的建议值.     

从线粒体DNA控制区基因探讨红腹锦鸡和白腹锦鸡的分类关系

用聚合链式反应(PCR)和直接测序的方法测定红腹锦鸡(Chrysolophus pictus)和白腹锦鸡(C.amherstiae)各5个样本线粒体DNA控制区的468 bp的序列,共发现26个变异位点.红腹锦鸡的序列变异率为0.90%,白腹锦鸡的序列变异率是0.17%,两者差异极显著.红腹锦鸡和白腹锦鸡的3种碱基(A,T,C)含量差异显著.根据Kumar双参数法计算两种锦鸡的遗传距离为0.035±0.008,按线粒体DNA控制区的进化速率2%/Myr计算,它们的分歧进化的时间大约是(1.75±0.40)Myr,结果支持它们是两个独立的种.红腹锦鸡和白腹锦鸡可能分别起源于秦岭以南地区和横断山脉.     

An MPI+OpenACC-Based PRM Scalar Advection Scheme in the GRAPES Model over a Cluster with Multiple CPUs and GPUs

A moisture advection scheme is an essential module of a numerical weather/climate model representing the horizontal transport of water vapor. The Piecewise Rational Method(PRM) scalar advection scheme in the Global/Regional Assimilation and Prediction System(GRAPES) solves the moisture flux advection equation based on PRM. Computation of the scalar advection involves boundary exchange, and computation of higher bandwidth requirements is complicated and time-consuming in GRAPES. Recently, Graphic...     

A Novel Cross-Project Software Defect Prediction Algorithm Based on Transfer Learning

Software Defect Prediction(SDP) technology is an effective tool for improving software system quality that has attracted much attention in recent years. However, the prediction of cross-project data remains a challenge for the traditional SDP method due to the different distributions of the training and testing datasets. Another major difficulty is the class imbalance issue that must be addressed in Cross-Project Defect Prediction(CPDP). In this work,we propose a transfer-leaning algorithm(TSboo...     

RBC: A Memory Architecture for Improved Performance and Energy Efficiency

DRAM-based memory suffers from increasing row buffer conflicts, which causes significant performance degradation and power consumption. As memory capacity increases, the overheads of the row buffer conflict are increasingly worse as increasing bitline length, which results in high row activation and precharge latencies. In this work, we propose a practical approach called Row Buffer Cache(RBC) to mitigate row buffer conflict overheads efficiently. At the core of our proposed RBC architecture, the rows with good spatial locality are cached and protected,which are exempted from being interrupted by the accesses for rows with poor locality. Such an RBC architecture significantly reduces the overheads of performance and energy caused by row activation and precharge, and thus improves overall system performance and energy efficiency. We evaluate RBC architecture using SPEC CPU2006 on a DDR4 memory compared to a commodity baseline memory system. Results show that RBC improves the overall performance by up to 2:24(16:1% on average) and reduces the memory energy by up to 68:2%(23:6% on average) for single-core simulations. For multi-core simulations, RBC increases the overall performance by up to1:55(17% on average) and reduces memory energy consumption by up to 35:4%(21:3% on average).     

基于分子动力学模拟的天然橡胶黏弹性材料力学行为

以天然橡胶为例,采用分子动力学模拟方法,研究了单轴拉伸条件下材料分子链聚合度参数p、环境温度T和加载率R对黏弹性材料力学性能的影响.结果 表明,材料应力随分子链聚合度和加载率的增加而增加,随温度的升高而降低,低温高频下材料呈现出塑性特点.在R=108 s-1,T=250 K的条件下,p=20,40时,材料应力峰值分别为...     

Helmholtz Solving and Performance Optimization in Global/Regional Assimilation and Prediction System

Despite efficient parallelism in the solution of physical parameterization in the Global/Regional Assimilation and Prediction System(GRAPES), the Helmholtz equation in the dynamic core, with the increase of resolution, can hardly achieve sufficient parallelism in the solving process due to a large amount of communication and irregular access. In this paper, optimizing the Helmholtz equation solution for better performance and higher efficiency has been an urgent task. An optimization scheme for the parallel solution of the Helmholtz equation is proposed in this paper. Specifically, the geometrical multigrid optimization strategy is designed by taking advantage of the data anisotropy of grid points near the pole and the isotropy of those near memory equator in the Helmholtz equation,and the Incomplete LU(ILU) decomposition preconditioner is adopted to speed up the convergence of the improved Generalized Conjugate Residual(GCR), which effectively reduces the number of iterations and the computation time.The overall solving performance of the Helmholtz equation is improved by thread-level parallelism, vectorization, and reuse of data in the cache. The experimental results show that the proposed optimization scheme can effectively eliminate the bottleneck of the Helmholtz equation as regards the solving speed. Considering the test results on a 10-node two-way server, the solution of the Helmholtz equation, compared with the original serial version, is accelerated by 100, with one-third of iterations reduced.     

Connecting informal networks to management of tacit knowledge

The relationship between tacit knowledge and informal networks has not been fully explored.Tacit knowledge cannot be well managed directly,because it is deeply embedded in individual actions and experiences.This study proposes an approach to managing informal networks as a new middle way to facilitate the sharing and transferring of tacit knowledge,owing to the fact that tacit knowledge is mostly shared and transferred through informal networks.To support the idea of the approach,an empirical case study of applying the approach to management of a large scientific project is also included.Our findings suggest that informal networks play essential roles for management of tacit knowledge,and thus good management of informal networks can lead to efficient sharing and transferring of tacit knowledge.