本体语义相似度自适应综合加权算法研究

本体语义相似度计算是解决语义网中语义异构的关键环节。通过对传统语义相似度计算方法的分析研究,引入本体层次结构,给出基于信息内容、距离、属性的语义相似度改进计算方法,并采用主成分分析法,提出一种自适应相似度综合加权计算方法(ACWA),以解决传统综合加权计算时人工赋权的不足。实验结果表明,提出的ACWA算法的计算结果与参照标准之间的皮尔森系数较传统算法平均高出了8.1%,有效提升了本体语义相似度计算的准确性。     

适用于车载自组织网络的稳定成簇算法

车载自组织网络中网络拓扑频繁变化、链路不稳定.若直接使用移动自组网的成簇算法,将会引起传输延时增大及丢包率上升等一系列问题.提出一种基于AP相似度改进的稳定成簇算法——SD成簇算法.本算法以节点之间的相似度(similarity)和周围节点度(degree)作为分簇依据,利用节点的地理位置信息和邻居拓扑信息进行簇头选举.NS2仿真结果表明,该算法能有效地改善车载自组织网络中簇结构的稳定性.     

Color‐edge detection based on discrimination of noticeable color contrasts

Color‐edge detection is an important research task in the field of image processing. Efficient and accurate edge detection will lead to higher performance of subsequent image processing techniques, including image segmentation, object‐based image coding, and image retrieval. To improve the performance of color‐edge detection while considering that human eyes are ultimate receiver of color images, the perceptually insignificant edges should avoid being over‐detected. In this article, a color‐edge detection scheme based on the perceptual color contrast is proposed. The perceptual color contrast is defined as the visible color difference across an edge in the CIE‐Lab color space. A perceptual metric for measuring the visible color difference of a target color pixel is defined by utilizing the associated perceptually indistinguishable region. The perceptually indistinguishable region for each color pixel in the CIE‐Lab color space is estimated by the design of an experiment that considers the local property due to local changes in luminance. Simulation results show that the perceptual color contrast is effectively defined and the color edges in color images are detected while most of the perceptually insignificant edges are successfully suppressed through the proposed color‐edge detection scheme. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 332–339, 2009     

热线风速仪低温测速的初步研究

由于测量低温下的速度需要热线探针在低温下的响应曲线,所以,获得低温下的热线探针的准确的响应曲线,便成为在低温下热线测速的基本前提.介绍了热线风速仪的标定原理与标定公式的修正,重点突出了热线风速仪在低温环境下的密封系统内的速度测量.概述了一套用于热线低温标定的实验装置,并给出了部分实验结果.     

Lower-error and area-efficient antilogarithmic converters with bit-correction schemes

In this article, we have proposed fast lower-error and area-efficient antilogarithmic converters. By employing new approximation schemes with two-region shift-and-add operations, our proposed converters can perform high-speed conversions from logarithmic numbers to binary numbers. Synthesis results show that our proposed converters can achieve time savings of over 32.5% and can save 42.3% of the area used compared with previously proposed methods. In addition, the percent error ranges for various logarithmic number system (LNS)-based operations used by our proposed logarithmic processor are lower than those of previous methods. Our proposed converters can be applied to LNS-based processors to ease the tremendous computation overhead and boost the performance.     

Decreased Expression of Plakophilin-2 and αT-Catenin in Arrhythmogenic Right Ventricular Cardiomyopathy: Potential Markers for Diagnosis

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a hereditary disease of the heart muscle. Clinical challenges remain, however, in identifying patients with ARVC in the early or concealed stages with subtle clinical manifestations. Therefore, we wanted to identify potential targets by immunohistochemical (IHC) analysis in comparison with controls. Pathogenic mutations were identified in 11 of 37 autopsied patients with ARVC. As observed from IHC analysis of the RV, expression of αT-catenin and plakophilin-2 is significantly decreased in autopsied patients with ARVC as compared to controls, and the decreased expression is consistent in patients with and without pathogenic mutations. Furthermore, ARVC specimens demonstrated a reduced localization of αT-catenin, desmocollin-2, desmoglein-2, desmoplakin, and plakophilin-2 on intercalated discs. These findings have been validated by comparing RV specimens obtained via endomyocardial biopsy between patients with ARVC and those without. The pathogenic mutation was present in 3 of 5 clinical patients with ARVC. In HL-1 myocytes, siRNA was used to knockdown CTNNA3, and western blotting analysis demonstrated that the decline in αT-catenin expression was accompanied by a significant decline in the expression of plakophilin-2. The aforementioned effect was directed towards protein degradation rather than mRNA stability. Plakophilin-2 expression decreases concurrently with the decline in CTNNA3 expression. Therefore, the expression of αT-catenin and plakophilin-2 could be potential surrogates for the diagnosis of ARVC.     

A new point contact surface acoustic wave transducer for measurement of acoustoelastic effect of polymethylmethacrylate

A new acoustic transducer and measurement method have been developed for precise measurement of surface wave velocity. This measurement method is used to investigate the acoustoelastic effects for waves propagating on the surface of a polymethylmethacrylate (PMMA) sample. The transducer uses two miniature conical PZT elements for acoustic wave transmitter and receiver on the sample surface; hence, it can be viewed as a point- source/point-receiver transducer. Acoustic waves are excited and detected with the PZT elements, and the wave velocity can be accurately determined with a cross-correlation waveform comparison method. The transducer and its measurement method are particularly sensitive and accurate in determining small changes in wave velocity; therefore, they are applied to the measurement of acoustoelastic effects in PMMA materials. Both the surface skimming longitudinal wave and Rayleigh surface wave can be simultaneously excited and measured. With a uniaxial-loaded PMMA sample, both acoustoelastic effects for surface skimming longitudinal wave and Rayleigh waves of PMMA are measured. The acoustoelastic coefficients for both types of surface wave motions are simultaneously determined. The transducer and its measurement method provide a practical way for measuring surface stresses nondestructively.     

CFD simulation of particle segregation in a rotating drum. Part I: Eulerian solid phase kinetic viscosity

Although the Eulerian approach coupling the kinetic theory of granular flow is usually used to study granular flows with relative lower solid fractions, it can be used to study relative denser granular flows if appropriate solid phase kinetic viscosity values were adopted. A granular bed surface fitting (BSF) method is proposed to determine the appropriate solid phase kinetic viscosities of the granular flows in a rotating drum. The specularity coefficient is also used to address the interaction between particles and the drum wall. The BSF solid phase kinetic viscosity increases with decreasing of particle sizes and drum rotational speeds. The BSF solid phase kinetic viscosity and the specularity coefficient follow a power-law relationship with 0.6–1.1 as the exponent of the specularity coefficient. The BSF solid phase kinetic viscosities for the particles of two different sizes are used to study particle segregation in a rotating drum. The core thickening segregation mechanism and the segregation band formations are well predicted.     

面向批料流测量的科氏质量流量计正交解调方法实现

为了提高科氏质量流量计在批料流工况下的测量精度,根据正交解调算法具有快速响应的特点,选取该算法作为批料流下的信号处理方法,并解决实现过程中的技术难点。利用正弦信号周期性的特点,实现解调信号单周期有限点数据循环调用;采用FIR陷波器和IIR低通滤波器级联完成对解调后信号的滤波,在保证滤波效果的同时降低了算法运算量;为了去除计算结果中的奇异点同时减小稳态波动,在相位差后期处理中加入两级平均;优化了算法实现过程中的资源分配。在此基础上,研制了科氏质量流量变送器,并进行了单相流和批料流标定实验,其测量误差小于0.1%,重复性小于0.05%。实验结果表明,正交解调算法在批料流下具有较好的测量精度,同时所研制的变送器具有较好的性能。