基于改进遗传算法的最佳阈值的图像分割

设计了改进的遗传算法,通过内外两层的选择、交叉和变异等遗传操作,快速逼近最佳阈值,大大缩短最佳阈值图像分割中阈值的选取时间,提高分割效率;通过实验比较,证实改进的遗传算法在最佳阈值的图像分割上优于传统的遗传算法。     

基于ASP.NET的交叉表的实现方法

在WEB应用开发中,需要通过交叉表技术显示多表的数据项使得显示效果更清晰。交叉表查询是在原有关系表数据的基础上,将原表中的某一字段数据转化为字段名称所形成的关系结构。这样我们就可以非常容易地进行数据汇总统计,统计要求符合中国报表特色。文章结合实例对交叉表查询的创建进行了研究,由简单到复杂,一步步得出最终解决方案。     

ASP.NET中应用交叉表的通用函数

在WEB应用开发中,需要通过交叉表技术显示多表的数据项,本文在分析典型表实例基础上,给出了关键的SQL语句,并提炼封装成函数,用于所有交叉显示的数据表,解决了WEB开发人员的难点问题。     

基于液晶光阀的可编程光学二值逻辑系统

基于液晶光阀的可编程光学二值逻辑系统张子北，刘立人（中国科学院上海光学精密机械研究所）秦伟芳（中国科学院上海技术物理研究所）摘要基于双轨编码和分束合束，本文提出一种能够实现两个二值输入变量的逻辑系统。通过控制偏振片的偏振方向，该系统能够实现所有十六种...     

遗传算法在图像阈值分割中的应用

图像分割是目标检测和识别的基础,对所采集到的图像进行分割处理是图像识别跟踪技术中实现目标检测的一种重要技术手段;遗传算法是一种优化算法,利用其高效、并行的寻优能力,通过选择、交叉和变异等遗传操作快速逼近最佳阈值,大大缩短图像阈值分割中阈值的选取时间,提高分割效率;介绍了遗传算法在图像阈值分割领域的应用研究进展。     

智能隐形眼镜

青光眼是仅次于白内障的第二大致盲疾病，更可怕的是青光眼是不可逆转的，因此尽早的诊断出青光眼将可以最大限度的减小这种疾病对于视力的损害。而这款由美国加州大学戴维斯分校的研究人员设计的智能隐形眼镜就能够尽早的帮助你诊断出青光眼。     

交叉表查询在Access中的应用

Access是Microsoft Office的一个重要组件，是一种非常实用的数据库管理系统软件。本文通过介绍在Access中创建交叉表查询的几种方法，展示了交叉表查询在解决实际问题中的应用。     

基于ASP.NET的交叉表的一种新的实现方法

对数据库的交叉表的实现有很多的实现方案,但是以前的实现方法不能在作为字段名称的原表中的字段数据未知时实现交叉表,本文提出的这种实现方法能解决这一情况,并结合实例介绍这种方案的具体实现。     

基于Rao-Stirling指数和LDA模型的领域学科交叉主题识别——以纳米科技为例

【目的/意义】基于Rao-Stirling 指数和LDA模型进行领域学科交叉主题识别,并以纳米科技为例验证将 Rao-Stirling 指数和LDA模型用于领域学科交叉主题识别的有效性和适用性。【方法/过程】基于Rao-Stirling 指数 测度领域文献学科交叉程度,设定阈值发现高度学科交叉文献。基于LDA模型对筛选出的学科交叉文献进行主题 识别,发现学科交叉点和学科交叉研究主题。【结果/结论】基于Rao-Stirling 指数从引文的角度进行领域文献学科 交叉测度可以有效地发现与某领域相关的学科交叉文献,且有利于大数据集的学科交叉文献发现研究的实现。基 于LDA模型进行学科交叉主题识别可以有效地发现学科交叉主题。两方法的组合应用为发现某领域学科交叉主 题研究提供一种新视角。     

基于ASP.NET的交叉表的—种新的实现方法

对数据库的交叉表的实现有很多的实现方案，但是以前的实现方法不能在作为字段名称的原表中的字段数据未如时实现交叉表，本文提出的这种实现方法能解决这一情况，并结合实例介绍这种方案的具体实现。     

Discovery of neural circuits for saccadic modulation of visual perception

In daily life, we move our eyes frequently to search for or fixate a target of interest with the retinalfovea. Usually, the eyes would dart from one position to another in the visual field at velocities higher than 500 degrees per second. This rapid eye movement is called a saccade.     

果蝇的视觉模式识别具有视网膜位置不变性

2004年8月13日出版的Science发表了由生物物理研究所主持、与德国沃尔兹堡大学合作完成的“果蝇视觉模式识别具有视网膜位置不变性”的研究成果。本文介绍了该项成果的研究背景、意义、主要创新点及方法。     

Zinc phosphate dental cements

A spectrophotometric method of determining total visual transmission and visual density of non-neutral light filters is described. In addition, this method is utilized in determining density and gamma intensification produced by tones in color motion picture work and the importance of intensification control is emphasized.     

Fusion estimation for stochastic uncertain systems with time-correlated rician fading channels

In this article, a fusion estimation scheme is proposed for stochastic uncertain systems with time-correlated fading channels (TFCs). A batch of random variables obeying Gaussian distributions is employed to describe the parameter uncertainties. The sensor communicates with the local filter through a TFC where the evolution of the channel coefficient is characterized by a certain dynamic process with one-step correlated noises. For further analyzing the effects of TFCs, a class of additional variables is first introduced by augmenting the dynamics of channel coefficients and the concerned system. Then, a new group of modified local filters is developed and the unbiasedness of local filters is examined by means of inductive method. Furthermore, the filter gains which minimize the local filtering error covariances are designed for the modified local filters in the simultaneous presence of stochastic uncertainties and TFCs. Subsequently, the cross-covariances among local estimates are computed iteratively and, based on the obtained cross-covariances as well as the unbiased local estimates and their corresponding filtering error covariances, a fusion estimate is obtained by using weighted least square fusion method. Finally, the effectiveness of the proposed fusion estimation scheme is verified by two examples.     

Optimization of configurations of field problem grids using network models

Optimization of grid configurations decreases the discretization error in the numerical solution of field problems. In this paper, the theoretical and algorithmic aspects of optimizing configurations of grids used in equilibrium, potential-type field problems is presented. The criterion for establishing the optimum grid and the steps required to move to the optimum grid are given. Sensitivity network modelling is invoked to systematically form matrices required in the algorithm. One-dimensional examples are presented to illustrate the validity of the approach.     

带隔离变压器的Cuk型有源功率因数校正的研究与设计

随着电力电子技术的发展,各种电力电子设备应用于电网,给电网带来谐波问题,各种谐波滤波器也应运而生,但这只是一种先污染后治理的被动办法,APFC是一种主动的办法,它用于开关电源前级整流器,输入电流为正弦波,不对电网产生污染。全文围绕一种新颖的基于隔离型Cuk变换器的有源功率因数校正电路的设计,从Cuk变换器的基本单元入手,分析了Cuk变换器的工作原理,在此基础上,确定了基于隔离型Cuk变换器APFC电路的基本拓扑。     

高二英语期中考试的预测效度研究

预测效度是语言测试领域里相对来说比较新的题材,自20世纪50年代以来受到一些语言测试研究者的关注。本文以预测效度的理论为依据,目的在于通过分析高二学生的英语期中与期末考试的分数来研究英语期中考试的预测效度。研究结果将对高中英语教与学有很大作用。     

A new type of transitional filter based on summation of polynomials

A new transitional filter based on the sum of filter polynomials is proposed and discussed. It shall be shown that the approach allows for greater flexibility in adjusting passband and stopband gain shapes. The sensitivity of the filter transfer function is analyzed and related to the approximation problem. Some new modified classical filters are also derived including maximally flat (Butterworth) and equiripple (Chebyshev) types. Several examples of combining Butterworth, Chebyshev and sync-tuned filters are presented and compared to those obtained using the conventional product method. The new transitional filter provides an alternative to other forms and provides a means for isolating the effects of non-uniformly distributed pole angles.     

Cell-cell proximity effects in multi-cell electroporation

We report a fundamental study of how the electropermeabilization of a cell is affected by nearby cells. Previous researchers studying electroporation of dense suspensions of cells have observed, both theoretically and experimentally, that such samples cannot be treated simply as collections of independent cells. However, the complexity of those systems makes quantitative modeling difficult. We studied the change in the minimum applied electric field, the threshold field, required to affect electropermeabilization of a cell due to the presence of a second cell. Experimentally, we used optical tweezers to accurately position two cells in a custom fluidic electroporation device and measured the threshold field for electropermeabilization. We also captured video of the process. In parallel, finite element simulations of the electrostatic potential distributions in our systems were generated using the 3-layer model and the contact resistance methods. Reasonably good agreement with measurements was found assuming a model in which changes in a cell''s threshold field were predicted from the calculated changes in the maximum voltage across the cell''s membrane induced by the presence of a second cell. The threshold field required to electroporate a cell is changed ∼5%–10% by a nearby, nearly touching second cell. Cells aligned parallel to the porating field shield one another. Those oriented perpendicular to the field enhance the applied field''s effect. In addition, we found that the dynamics of the electropermeabilization process are important in explaining observations for even our simple two-cell system.     

Circuit state analysis using chaotic signal excitation

A new testing method for analog circuit is proposed in this paper. A low-pass Butterworth filter is taken as the typical system under test (SUT) since the analog circuits in different types of electronic systems can be regarded as the low-, band- or high-pass active (passive) filters. The chaotic signal, which is generated by an improved Chua's circuit, is employed as the excitation signal of SUT. The SUT is a “narrowband” system compared with the bandwidth of input signal, whose state is analyzed with an error-tracking approach. The experimental result depicts that this testing method can efficiently detect the change of the circuit parameter. Besides, another eight features are extracted from the output signal of SUT for analyzing the SUT states. A discussion is made for comparing the effectiveness of each feature according to the testing results.