Cytoplasm and nucleus segmentation in cervical smear images using Radiating GVF Snake

A Radiating Gradient Vector Flow (RGVF) Snake aiming at accurate extraction of both the nucleus and cytoplasm from a single-cell cervical smear image is proposed. After preprocessing, the areas in the image are roughly clustered into nucleus, cytoplasm and the background by a spatial K-means clustering algorithm. After initial contours are extracted, the image is segmented using RGVF. RGVF involves a new edge map computation method and a stack-based refinement, and is thus robust to contaminations and can effectively locate the obscure boundaries. The boundaries can also be correctly traced even if there are interferences near the cytoplasm and nucleus regions. Experiments performed on the Herlev dataset, which contains 917 images show the effectiveness of the proposed algorithm.     

A bootstrap approach for lower injury levels of the risk curves

Survival analysis is widely applied to develop injury risk curves from biomechanical data. To obtain more accurate estimation of confidence intervals of parameters, bootstrap method was evaluated by a designed simulation process. Four censoring schemes and various sample sizes were considered to investigate failure time parameters corresponding to low-level injury probabilities. In the numerical simulations, the confidence interval ranges developed by bootstrapping were about two-third of the corresponding ranges calculated by asymptotical normal approximation and showed highest reduction for censored datasets with smaller sample size (≤ 40). In analysis of two experimental datasets with reduced sample sizes and mixed censored data, it was shown that the bootstrapping reduce significantly the confidence intervals as well. The results presented in this study recommend using bootstrapping in development of more accurate confidence intervals for risk curves in injury biomechanics, which consequently will lead to better regulations and safer vehicle designs.     

Global stabilization of a chain of integrators with input saturation and disturbances: A new approach

In this article, we solve the problem of global stabilization for a chain of integrators in the presence of input saturation and disturbances. A novel and elegant approach to solve this problem, in the absence of disturbances, was proposed by Teel (1992) using saturation functions and coordinate transformation. With Teel’s work as a foundation, many results have been proposed to improve the performance of controllers for a chain of integrators. Naturally, all such approaches also inherited the limitations of Teel’s approach. Most importantly, in the presence of uncertainties and disturbances, the transformation introduced in Teel (1992) would considerably shrink the region where the controller is unsaturated and, severely limit the level of uncertainties and disturbances which can be tolerated. In order to overcome these difficulties, a conceptually different approach which does not rely on the coordinate transformation is presented in this work. Specifically, modified saturation functions are directly applied to the tracking error of actual states as opposed to transformed fictitious states to develop a globally stable controller. The proposed controller is less conservative in terms of the level of uncertainties and disturbances which can be handled. In addition, arbitrarily good disturbance rejection in the unsaturated region can be achieved theoretically. Comparative simulation studies performed on a third order integrator chain verified the effectiveness of the proposed scheme.     

基于多媒体网络的综合英语多元互动教学模式研究

互动在语言教学中由来已久,随着多媒体网络技术的迅猛发展,多元互动教学模式的可行性和优越性日益凸显出来。本文详细阐述了多元互动教学模式在综合英语教学中的建构,着重探讨了基于多媒体网络的综合英语多元互动的教学实践,旨在探讨如何通过有效的教学互动以达到优化教学效果的目的。     

国债市场的流动性套利及其实证检验

提出了一种在保持一定流动性风险的情况下构建国债套利组合的方法,应用线性规划技术,将国债的持有期风险因素引入到约束条件中,进而求解出实现最大期初套利的国债投资组合。通过对我国上交所25种债券的实证检验,发现套利收益与组合的持有期风险成正比,与流动性指标成反比,这证明了在考虑债券流动性风险的情况下,进行债券套利操作不一定会带来可观的收益。     

全站仪进行跨海面高程测量的应用及验证

海面高程的传递是水准测量中的难题.以宁波市象山县某围堤工程变形测量为例,对全站仪进行跨海面高程测量进行了成功应用,并用GPS拟合高程测量方法和平均海平面法进行了验证,结果合理.     

基于软件平台实现自适应MIMO-OFDM系统信道评估

正交频分复用技术由于具有频带利用率高和抗多径干扰能力强等优点,近年来在无线音频广播、无线视频广播、无线局域网等方面得到广泛的应用。然而,对OFDM系统进行准确的信道估计一直是其技术难点之一;加之MIMO技术虽然能有效的提高系统容量,但是同时也大大提高了系统的复杂度,这就进一步加大了对MIMO-OFDM系统进行信道估计的难度。在前人工作的基础上,对目前各常用信道评估方法实现复杂度与准确度进行分析,经过模拟仿真选择最适宜MIMO-OFDM系统评估手段进行研究。同时,由于OFDM系统本身对于信号同步性与正交性的苛刻要求,尤其在高容量高速率的实际应用中,其硬件实现往往需要付出高昂的成本代价;拟通过另一角度,研究在低成本、允许一定系统延迟、相对系统容量较低、传输速度不高的应用中,例如:短信业务、同区域语言服务等,仅搭建相应的软件平台实现真实仿真。     

Segmenting customers by transaction data with concept hierarchy

The segmentation of customers is crucial for an organization wishing to develop appropriate promotion strategies for different clusters. Clustering customers provides an in-depth understanding of their behavior. However, previous studies have paid little attention to the similarity of different items in transaction. Lack of categories and concept levels of items, results from item-based segmentation methods are not as good as expected. Through employing a concept hierarchy of items, this study proposes a segmentation methodology to identify similarities between customers. First, the dissimilarity between transaction sequences is defined. Second, we adopt hierarchical clustering method to segment customers by their transaction data with concept hierarchy of consumed items. After segmentation, three cluster validation indices are used for optimizing the number of clusters of customers. Through the compassion of normalized index, the segmentation method proposed by this study rendered better results than other traditional methods.     

改性高岭土上甲苯的选择性硝化(IV)

应用Ｍｅｎｋｅ条件，在改性高岭土固体酸催化下，甲苯能被浓硝酸对位选择性硝化，表现在对邻硝化产物比例达到１．５。     

DNA immobilization and SAW response in ZnO nanotips grown on LiNbO3 substrates.

DNA immobilization enhancement is demonstrated in a structure consisting of ZnO nanotips on 128 degrees Y-cut LiNbO3. The ZnO nanotips are grown by metalorganic chemical vapor deposition (MOCVD) on the top of a SiO2 layer that is deposited and patterned on the LiNbO3 SAW delay path. The effects of ZnO nanotips on the SAW response are investigated. X-ray diffraction and scanning electron microscopy are used to analyze the ZnO nanotips, which are of single crystalline quality, and they are uniformly aligned with their c-axis perpendicular to the substrate surface. The photoluminescence (PL) spectrum of the ZnO nanotips shows strong near bandedge transition with insignificant deep level emission, confirming their good optical property. DNA immobilization enhancement is experimentally validated by radioactive labeling tests and SAW response changes. The ZnO nanotips enhance the DNA immobilization by a factor of 200 compared to ZnO film with flat surface. DNA hybridization with complementary and noncomplementary second strand DNA oligonucleotides is used to study the selective binding of the structure. This device structure possesses the advantages of both traditional SAW sensors and ZnO nanostructures.