基于一致性直方图的超声乳腺图片分割方法

为了在乳腺超声图像中准确的分割出病灶,提出了新的一致性定义,把纹理信息应用到计算一致性中.基于最大熵准则求一致性阈值,把超声图片分为两个子集,一致性区域和非一致性区域;对一致性区域采取求直方图谷值的方法分割,而用邻域信息处理非一致性区域,从而完成对图像的分割.实验结果表明:该分割过程既考虑了图像的局部信息,又考虑了全局信息,弥补了传统的直方图分割算法无法包含局部信息的缺陷.算法处理结果得到了超声医学专家的认可;通过采用差异实验方法评估,取得了理想的效果.     

用于实现(k,e)-匿名模型的MDAV算法

MDAV算法是一种高效的微聚集算法,但它未考虑等价类中敏感属性多样性问题,生成的匿名表不能抵制同质性攻击和背景知识攻击。针对该问题,提出一种能够实现(k,e)-匿名模型的MDAV算法,简称(k,e)-MDAV算法。该算法将距离类中心最近的至少k个不同敏感值的元组聚为一类,并要求每个类内敏感属性值最大差异至少为e。实验结果表明,该算法能够生成满足(k,e)-匿名模型的匿名表。     

面向同构型多处理机系统的动态负载平衡算法

为了解决同构型多处理机系统中的负载不平衡问题,提出一种分布式控制、发送者驱动的动态平衡算法,该算法利用CPU队列长度衡量处理机负载状态、利用进程执行时间选取适合被迁移的负载、利用较完备的消息机制传播处理机负载状态和负载平衡要求,适用于计算密集型任务.实验结果验证了该算法的有效性.     

超导核磁共振成像主磁体无源数值匀场技术的研究

本文提出了超导核磁共振成像主磁体无源数值匀场的概念,发展了一种优化无源数值匀场方法。将优化无源数值匀场方法应用于中国科健有限公司研制的国产第一台超导核磁共振成像主磁体,其结果令人满意。     

Comparison of selection procedures for the formation of homogeneous groups in clinical tests of dental care agents

Dental trials of new dental care formulations are studied with regard to specific quality characteristics such as inhibition of plaque formation and reduction of gingival bleeding, and require homogeneous panels of test persons in which both systematic and random sources of experimental error are excluded. The homogeneous panels must be formed from an available pool of test persons (global panel) so that each panel as a subset presents the same dental features on average and can be compared statistically one with another. This is a necessary condition for a valid scientific conclusion to be obtained from comparative dental studies. This type of homogeneous group division of a global panel can clearly be based on other medical features.
Four selection procedures for the formation of homogeneous panels from the global panel were compared quantitatively with regard to their efficiency and homogeneity of group division, namely:
— randomization method;
— block target method;
— median pair method;
— block median pair method.
With the exception of the randomization method, which can be applied more generally, the other selection methods require a preliminary study of the available test persons with regard to their medical features.
A comparison of the four selection procedures shows that the three other methods are more likely to provide more homogeneous panels than the randomization method.
Comparaison des procedures de selection concernant la formation de groupes homogènes dans les tests cliniques des agents de soins dentaires     

化学均匀性对PTCR陶瓷材料阻温系数α的影响

本文研究了两种不同化学组成均匀性的ＰＴＣＲ陶瓷材料晶相转变特性和电容－温度关系，初步探究了化学组成均匀性对于ＰＴＣＲ陶瓷材料阻温系数α的影响关系，结果表明；提高ＰＴＣＲ陶瓷材料的化学组成均匀性，可以使其晶相转变温区变窄以及电容随温度变化陡度增大，从面导致了ＰＴＣＲ陶瓷材料阻温系数的增大。     

Frequency analysis of upper cauvery flood data by L-moments

The objectives of the present study are to investigate the hydrological homogeneity of Upper Cauvery annual maximum flow data and to select a suitable distribution for the frequency analysis. The L-moments method is used in this analysis. The Upper Cauvery river basin is shown to be hydrologically heterogeneous. The 3 parameter log normal and the generalized extreme value distributions are recommended for the frequency analysis of data in this region.     

重离子束均匀度的测定及治癌束流成形的模拟试验

采用５０μｍ厚聚碳酸酯薄膜，利用核径迹测技术测得φ４０ｍｍ的２５ＭｅＶ／ｕ＾４０Ａｒ＾１４＋离子束的均匀度在散焦情况下为３２．７％，在Ｄ“散焦＋样品旋转”情况下为５２．４％。还采用多层聚碳酸酯薄膜组件作为肿瘤块等效材料，进行了重离子束治癌束流成形模拟试验。     

论电路齐次定理和叠加定理的关系

齐次定理和叠加定理是由线性线性电路两个重要的定理。通过分析,指出对单一激励的电路,如果该电路满足齐次定理或者叠加定理,那么,该电路一定是线性电路。对单一激励的电路,齐次定理已经充分表达了线性电路的线性性质。对多个激励的电路,如果该电路满足可加性,那么,该电路一定是线性电路。反之,如果电路仅满足齐次定理,则该电路不一定是线性电路。尽管叠加定理是线性系统可加性在电路中的应用,但叠加定理和可加性的内涵是有所区别的,不能通过电路是否满足叠加定理来判定电路的齐次性或电路是否满足齐次定理。本文的讨论可供讲授电路理论课程的教师参考。     

Global decentralised stabilisation for a class of uncertain large-scale high-order upper-triangular nonlinear systems

This paper considers the global decentralised stabilisation problem for a class of uncertain large-scale high-order upper-triangular nonlinear systems. First, a local linear decentralised controller is recursively constructed based on the generalised homogeneous system theory and the adding a power integrator method. Second, aiming for global stabilisation, a series of nested saturation functions are integrated with the proposed local linear decentralised controller. Then, it is proved that the obtained decentralised saturated controller will render the whole closed-loop system globally asymptotically stable. Due to the flexibility of the generalised homogeneous method, the proposed control approach not only weakens the existing restrictions imposed on the interconnected nonlinearities, but also can be applied to a more general class of upper-triangular nonlinear systems. Furthermore, two simulations examples are conducted to show the effectiveness of the proposed control scheme.