基于功能磁共振的情绪脑机制研究

为探讨不同效价情绪图片的加工特点,考察被试在对不同效价的情绪图片加工时脑半球上的差异,利用脑功能磁共振成像技术,对情绪加工实验的被试进行数据采集,并对采集的数据用统计参数映射技术进行处理分析。研究发现情绪刺激加工的过程中,脑激活区域明显和前额叶,顶叶相关,而且是情绪功能相关联的主要位置。这表明人类情绪的反应并不仅仅是由边缘系统控制,在情绪刺激作用下,整个丘脑系统,边缘系统都参与其中进而形成一本复杂的情绪中枢机制。     

自适应近邻的局部线性嵌入算法

在局部线性嵌入算法(LLE)中寻找最优近邻数常用试凑法进行搜索,需要大量的时间才能得到最优结果.为此提出基于自适应近邻的局部线性嵌入算法( ANLLE),算法首先给出一个相似性度量函数,然后据此为各个样本设定阈值,根据每个样本周围数据分布情况,为每个样本自动设置不同近邻数,最后在各个样本近邻数不相同情况下进行数据降维及待测样本的分类.在人脸数据库及手写数字数据库上的对比实验表明,ANLLE算法识别性能高于标准LLE算法及邻域线性嵌入算法(NLE).     

一维河流水团示踪试验数据的模糊线性回归

将模糊线性回归的概念引入分析河流水团示踪试验数据、确定河流水质参数的计算过程中,建立计算河流水质参数的模糊线性回归模型,利用该模型能计算出不同置信水平下水质参数的取值范围。算例验证结果表明,应用模糊线性回归模型可以有效地确定河流的水质参数,且计算过程具有一定的稳定性、可靠性和灵活性,模糊线性回归模型是分析河流水团示踪试验数据、确定河流水质参数的一种有效的途径。     

龙滩水电站励磁系统国产化改造及新技术应用

从巨型机组励磁系统设备维护的经济性、技术服务的快捷性、设备升级改造的方便性以及对核心控制技术的可控性等方面考虑,龙滩水电站机组励磁系统的国产化改造显得尤为迫切。对龙滩水电站700MW机组励磁系统进行了国产化改造,介绍了改造实现方法和相关新技术的应用。     

Fast linear systolic matrix vector multiplication

The systolic concept in the parallel architecture design proposed by the H. T. Kung [1,2] obtains high throughput and speedups. The linear array for the matrix vector multiplication executes the algorithm in 2n ? 1 time steps using 2n ? 1 processors. Although the speedup obtained is very high, the efficiency is very poor (typical values of 25% efficiency for problem size greater than 10). H. T. Kung proposed an idea for a linear systolic array using two data streams flowing in opposite directions. However, the processors in the array perform operations in every second time moment.

Attempts to improve this design have been made by many researchers. Nonlinear and folding transformations techniques [3,4,5] only decrease the number of processors used to half the size, but do not affect the time.

We propose the use of a fast linear systolic computation procedure to obtain a solution that uses 3n/2 processors and executes the algorithm in 3n/2 time steps for the same cells, the same communication and the same regular data flow as the H. T. Kung linear array. Only the algorithm is restructured and more efficiently organized. Now the processors are utilized in every time step and no idle steps are required.     

Parallelizable restarted iterative methods for nonsymmetric linear systems. part I: Theory

Large sparse nonsymmetric problems of the form A u = b are frequently solved using restarted conjugate gradient-type algorithms such as the popular GCR and GMRES algorithms. In this study we define a new class of algorithms which generate the same iterates as the standard GMRES algorithm but require as little as half of the computational expense. This performance improvement is obtained by using short economical three-term recurrences to replace the long recurrence used by GMRES. The new algorithms are shown to have good numerical properties in typical cases, and the new algorithms may be easily modified to be as numerically safe as standard GMRES. Numerical experiments with these algorithms are given in Part II, in which we demonstrate the improved performance of the new schemes on different computer architectures.     

Privacy in instant messaging: an impression management model

Instant messaging (IM) has evolved into an important tool for collaborative work. It supports informal near-synchronous communication and fosters awareness of the online presence of one's communication partners. Like all awareness systems, IM runs into concerns regarding privacy. Drawing upon prior literature and exploratory interviews, we postulate a model that posits impression management as an underlying cause for privacy desires of IM users. We verify our hypotheses using linear structural modelling on data from a large online survey of IM users across the US. The model establishes that the desire for privacy in IM arises due to the desire for impression management (both directly, as well as indirectly through the desire for visibility of one's impression to oneself). Based on this model, we suggest that IM systems could support privacy needs of users better by providing them with more knowledge and control over aspects that affect their IM-conveyed impression on others (i.e. by making impression management functionality available). Specifically, to help convey and sustain appropriate impressions on IM contacts, IM systems should allow for increased visibility of one's actions to oneself, facilitate easy comparison of one's practices with those of others, and allow one to view oneself from the perspective of others and to make finer-grained adjustments to IM settings than is possible today.