熔铝电阻率测量系统的研制

熔铝电阻率的测量基于电涡流原理，设计了传感器的结构和标定方法。为了简化测量熔铝电阻率的硬件电路，在信号处理电容中采用了LVDT专用芯片AD598硬软件结合消除了温度影响，在熔铝及铝基合金的凝固研究中得到实用。     

电阻层析成像系统敏感场特性分析及仿真

电阻层析成像系统敏感场受多相流介质分布的影响,敏感场分布数据作为图像重建所需的先验数据必须通过理论计算的方法得到,为降低敏感场的软场误差,提高重建图像质量,对敏感场分布进行深入的分析是极为必要的。论文在分析电阻层析成像的基本原理的基础上,采用有限元的方法建立了敏感场的数学模型,通过对离散介质场域的研究,分析了影响敏感场分布的因素及规律,完成了敏感场分布计算及可视化仿真。实验证明建立的有限元模型是正确的,而且敏感场分布符合实际,运算速度在10s左右,为相关的图像重建算法提供了依据。     

基于FPGA的生物电阻抗成像系统设计

根据电阻抗断层成像技术要求,设计了以Spartan3E系列XC3S500E FPGA为核心的16电极生物电阻抗成像系统,系统嵌入8 bit微处理器PicoBlaze实现逻辑控制并产生激励信号实现高速A/D采集及实现数字解调,通过RS232将采集数据传输到PC机,重建人体内部的电阻率分布或其变化图像。为广泛应用研究电阻抗断层成像技术提供一种硬件设计方案。     

128电极电阻抗断层成像数据采集系统设计

以实现旋转电极法电阻抗断层成像数据采集自动化为目的,设计开发了一种基于NIOS Ⅱ处理器、拥有128个电极的旋转电极法电阻抗断层成像数据采集系统.进行了数据采集实验,在PC机上获得了采集结果,验证了系统的可靠性.     

Identification of control chart patterns using wavelet filtering and robust fuzzy clustering

This paper proposes a hybrid framework composed of filtering module and clustering module to identify six common types of control chart patterns, including natural pattern, cyclic pattern, upward shift, downward shift, upward trend, and downward trend. In particular, a multi-scale wavelet filter is designed for denoising and its performance is compared to single-scale filters, including mean filter and exponentially weighted moving average (EWMA) filter. Moreover, three fuzzy clustering algorithms, based on fuzzy c means (FCM), entropy fuzzy c means (EFCM) and kernel fuzzy c means (KFCM), are adopted to compare their performance of pattern classification. Experimental results demonstrate that the excellent performance of EFCM and KFCM against outliers, especially in the case of high noise level embedded in the input data. Therefore, a hybrid framework combining wavelet filter with robust fuzzy clustering is suggested and proposed in this paper. Compared to neural network based approaches, the proposed method provides a promising way for the on-line recognition of control chart patterns because of its efficient computation and robustness against outliers.     

用于两相流检测电容层析系统成像的迭代算法

电容层析成像技术(ECT)在应用生产过程中作为一种在线检测技术而得到充分应用。通过精确测量ECT系统的12个电极之间的电容,并利用测量数据进行二维模型有限元法计算其电场敏感分布图,提出了一种迭代的成像算法。该迭代算法可比较精确地对管道横截面的两相流进行图像重建。并讨论了工业应用的实际问题和目前的技术上的缺陷性。     

基于聚类和SVD算法的模糊逻辑系统结构辨识

为了研究模糊逻辑系统新的结构辨识方法, 提出采用基于山峰函数的减法聚类算法构造模糊逻辑系统的初始结构, 并利用奇异值分解(SVD)算法分析了模糊规则与奇异值、累积贡献率以及索引向量的关系, 从而实现了模糊逻辑结构的优化. 最后, 对该算法的可行性和有效性进行了仿真验证和性能比较, 取得了较好的效果.     

多维输出SVR的ECT两相流图像重建方法

根据电容层析成像（ECT）中两相流识别问题的特点,提出基于多维输出支持向量回归机（MSVR）的图像重建算法。采用超球空间不敏感损失函数的MSVR是支持向量机理论的一个重要分支,它有效地克服了神经网络算法中的过学习问题,具有较强的泛化能力。近似迭代变权最小二乘法（IRWLS）在保证MSVR回归精度的基础上,有效地简化了其求解过程,可快速建立电容测量值与成像区域介电常数分布之间的非线性映射关系。对包含6种典型两相流流型的仿真数据进行实验。结果表明,该方法泛化能力强,图像重建精度高。     

The role of human factors in stereotyping behavior and perception of digital library users: a robust clustering approach

To deliver effective personalization for digital library users, it is necessary to identify which human factors are most relevant in determining the behavior and perception of these users. This paper examines three key human factors: cognitive styles, levels of expertise and gender differences, and utilizes three individual clustering techniques: k-means, hierarchical clustering and fuzzy clustering to understand user behavior and perception. Moreover, robust clustering, capable of correcting the bias of individual clustering techniques, is used to obtain a deeper understanding. The robust clustering approach produced results that highlighted the relevance of cognitive style for user behavior, i.e., cognitive style dominates and justifies each of the robust clusters created. We also found that perception was mainly determined by the level of expertise of a user. We conclude that robust clustering is an effective technique to analyze user behavior and perception.     

减法聚类-ANFIS在网络故障诊断的应用研究

提出了一种基于减法聚类-自适应模糊神经网络（ANFIS）的网络故障诊断建模方法。减法聚类算法生成初始模糊推理系统,ANFIS建立网络故障诊断原始模型,应用混合算法对模糊规则的参数进行训练并建立最终的模型。仿真实验表明基于减法聚类-ANFIS的建模方法是有效的;通过仿真结果比较,减法聚类-ANFIS的网络故障诊断能力及收敛速度均优于BP神经网络,更适合作为网络故障诊断模型。     

Development of a wireless stress/strain measurement system integrated with pressure-sensitive nickel powder-filled cement-based sensors

A wireless stress/strain measurement system is developed by integrating with pressure-sensitive sensors for health monitoring of concrete structures. The pressure-sensitive stress/strain sensors are fabricated by using nickel powder-filled cement-based composite. The wireless stress/strain measurement system integrated with these sensors is tested with compressive stress/strain in the range from 0 MPa/0 μ to 2.5 MPa/311.5 μ for performance evaluation. Experimental results indicate that the electrical resistivity of pressure-sensitive nickel powder-filled cement-based stress/strain sensors changes linearly and reversibly with the compressive stress/strain, and its fractional change goes up to 42.719% under uniaxial compression. The relationship between input (compressive stress/strain) and output (the fractional change in electrical resistivity) of the wireless stress/strain measurement system integrated with pressure-sensitive sensors is Δρ = −0.16894σ/Δρ = −1336.5. The wireless stress/strain measurement system can be used to achieve a sensitivity to stress/strain of 16.894% MPa⁻¹/0.13365%μ⁻¹ (a gauge factor of 1336.5) and a stress/strain resolution of 150 Pa/0.02 μ. The newly developed wireless stress/strain measurement system integrated with pressure-sensitive nickel powder-filled cement-based sensors has such advantages as high sensitivity to stress/strain, high stress/strain resolution, simple circuit and low energy consumption.     

Parallelization of a dynamic SVD clustering algorithm and its application in information retrieval

We describe an implementation of a parallel document clustering scheme based on latent semantic indexing, which uses singular value decomposition. Given a set of documents, the clustering algorithm is dynamic in the sense that it automatically infers the number of clusters to be output. The parallel version has been implemented on a LAN and on a dual‐core system. Experimental evaluation of the algorithm shows an average speed‐up of 6.22 for the LAN implementation and an average speed‐up of 3.71 for the dual‐core implementation, while still maintaining a precision and recall in the range [0.85, 1]. To put these implementations in the context of information retrieval, we use the parallel clustering algorithm and develop a document similarity search system. The similarity search system shows good performance in terms of precision and recall. Copyright © 2010 John Wiley & Sons, Ltd.     

Fuzzy risk assessment of mortality after coronary surgery using combination of adaptive neuro‐fuzzy inference system and K‐means clustering

In this paper, a fuzzy expert system based on adaptive neuro‐fuzzy inference system (ANFIS) is introduced to assess the mortality after coronary bypass surgery. In preprocessing phase, the attributes were reduced using a univariant analysis in order to make the classifier system more effective. Prognostic factors with a p‐value of less than 0.05 in chi‐square or t‐student analysis were given to inputs ANFIS classifier. The correct diagnosis performance of the proposed fuzzy system was calculated in 824 samples. To demonstrate the usefulness of the proposed system, the study compared the performance of fuzzy system based on ANFIS method through the binary logistic regression with the same attributes. The experimental results showed that the fuzzy model (accuracy: 96.4%; sensitivity: 66.6%; specificity: 97.2%; and area under receiver operating characteristic curve: 0.82) consistently outperformed the logistic regression (accuracy: 89.4%; sensitivity: 47.6%; specificity: 89.4%; and area under receiver operating characteristic curve: 0.62). The obtained classification accuracy of fuzzy expert system was very promising with regard to the traditional statistical methods to predict mortality after coronary bypass surgery such as binary logistic regression model.     

Development of a search and rescue robot system for the underground building environment

The underground building environment plays an increasingly important role in the construction of modern cities. To deal with possible fires, collapses, and so on, in underground building space, it is a general trend to use rescue robots to replace humans. This paper proposes a dual-robot system solution for search and rescue in an underground building environment. To speed up rescue and search, the two robots focus on different tasks. However, the environmental perception information and location of them are shared. The primary robot is used to quickly explore the environment in a wide range, identify objects, cross difficult obstacles, and so on. The secondary robot is responsible for grabbing, carrying items, clearing obstacles, and so on. In response to the difficulty of rescue caused by unknown scenes, the Lidar, inertial measurement unit and multiview cameras are integrated for large-scale 3D environment mapping. The depth camera detects the objects to be rescued and locate them on the map. A six-degree-of-freedom manipulator with a two-finger gripper is equipped to open doors and clear roadblocks during the rescue. To solve the problem of severe signal attenuation caused by reinforced concrete walls, corners and long-distance transmission, a wireless multinode networking solution is adopted. In the case of a weak wireless signal, the primary robot uses autonomous exploration for environmental perception. Experimental results show the robots' system has high reliability in over-the-horizon maneuvering, teleoperation of the door opening and grasping, object searching, and environmental perception, and can be well applied to underground search and rescue.     

CATALOG: a system for detection and rendering of internal log defects using computer tomography

This paper describes the design and implementation of a machine vision system CATALOG for detection and classification of some important internal defects in hardwood logs via analysis of computer axial tomography (CT or CAT) images. The defect identification and classification in CATALOG consists of two phases. The first phase comprises of the segmentation of a single CT image slice, which results in the extraction of 2D defect-like regions from the CT image slice. The second phase comprises of the correlation of the 2D defect-like regions across CT image slices in order to establish 3D support. The segmentation algorithm for a single CT image is a complex form of multiple-value thresholding that exploits both, the prior knowledge of the wood structure within the log and the gray-level characteristics of the image. The algorithm for extraction of 2D defect-like regions in a single CT image first locates the pith of the log cross section, groups the pixels in the segmented image on the basis of their connectivity and classifies each 2D region as either a defect-like region or a defect-free region using shape, orientation and morphological features. Each 2D defect-like region is classified as a defect or non-defect via correlation across corresponding 2D defect-like regions in neighboring CT image slices. The 2D defect-like regions with adequate 3D support are labeled as true defects. The current version of CATALOG is capable of 3D reconstruction and rendering of the log and its internal defects from the individual CT image slices. CATALOG is also capable of simulation and rendering of key machining operations such as sawing and veneering on the 3D reconstructions of the logs. The current version of CATALOG is intended as a decision aid for sawyers and machinists in lumber mills and also as an interactive training tool for novice sawyers and machinists. Received: 1 August 1997 / Accepted: 25 August 1999     

Design and prototype manufacturing of a feed system for Ku‐band satellite communication by using 3D FDM/PLA printing and conductive paint technology

In this study, the realization of a Ku‐band feed system for reflector antenna in satellite communication systems is presented using 3D printing and conductive paint methods. The system includes a corrugated conical horn antenna designed to operate at 10.5 to 18.5 GHz and an H‐plane waveguide diplexer to operate at 10.7 to 12.75 GHz and 17.3 to 18.4 GHz in receive (RX) and transmit (TX) bands, respectively. In the manufacturing of the structures, fused deposition modeling (FDM) technology and polylactic acid material are processed for 3D printing, where nickel and silver conductive‐based paints are used for coating purpose. The measurement results of the feed system are found to be in good agreement with simulations that the combined (nickel‐coated antenna and silver‐coated diplexer) structure has return loss of more than 10 dB and high gain performance of 12 to 17 dBi within the RX and TX bands of 10.7 to 12.75 GHz and 17.4 to 18.8 GHz, respectively; while rejection (isolation) level between TX and RX ports is higher than 60 dB. The complex structure containing several detailed shapes inside shows that this low‐cost production technique as compared to high‐cost CNC‐based metallic production technology can be used for the prototype structures or proof‐of‐concept type studies of Ku‐band systems.     

Development and evaluation of a system enhancing Second Life to support synchronous role‐based collaborative learning

Research and commercial interest toward 3D virtual worlds are recently growing because they probably represent the new direction for the next generation of web applications. Although these environments present several features that are useful for informal collaboration, structured collaboration is required to effectively use them in a working or in a didactical setting. This paper presents a system supporting synchronous collaborative learning by naturally enriching Learning Management System services with meeting management and multimedia features. Monitoring and moderation of discussions are also managed at a single group and at the teaching level. The Second Life (SL) environment has been integrated with two ad hoc developed Moodle plug‐ins and SL objects have been designed, modeled, and programmed to support synchronous role‐based collaborative activities. We also enriched SL with tools to support the capturing and displaying of textual information during collaborative sessions for successive retrieval. In addition, the multimedia support has been enhanced with functionalities for navigating multimedia contents. We also report on an empirical study aiming at evaluating the use of the proposed SL collaborative learning as compared with face‐to‐face group collaboration. Results show that the two approaches are statistically undistinguishable in terms of performance, comfort with communication, and overall satisfaction. Copyright © 2009 John Wiley & Sons, Ltd.     

Explicit and implicit animation with fuzzy constraints of a versatile multi‐body system for virtual hand surgery

This work is designed to control the movement of hand structural agents under external action, using the implicit animation driven by explicit animation technique (AI‐CAE technique). Starting from the configuration of a hand at rest obtained by a 3D scanner and after meshing of the structural agents, we seek the configuration of the rigid agents under orthopaedic surgeon external action and interacting reliance of deformable and rigid agents. We have developed a model and software tools to answer this interactive application with adaptive execution. The first contribution comes from notations and definition of a versatile multi‐body system dedicated to the explicit and implicit animation. The second contribution comes from the implicit animation driven by explicit animation itself, and from its ability to mimic the role of cartilages and ligaments. The resulting technique is applied to the bone structure consistency of a specific human hand in the context of virtual hand orthopaedic surgery. The versatile specific multi‐body is made up of hierarchical interacting agents conceivable as a construction set of rigid bones with cartilages–ligaments and underlying links. The explicit animation produces a desired configuration from geometric command parameters of torsion, flexion, pivot and axis shifting, given in a scenario subdivided into temporal sequences. The implicit animation controls the movement by implementing a physics‐based model and fuzzy constraints of position and orientation. It gives better configuration than the explicit animation because it takes into account the interactions between agents, and it gives a neat solution without the problems of complexity due to geometric modelling. A methodology based on the AI‐CAE technique is discussed, medical expertise and validation tests are presented. Copyright © 2011 John Wiley & Sons, Ltd.