改进的BP神经网络算法在水质监测中的应用

针对一类多输入多输出系统进行辨识, 以"A simulation of the western basin of Lake Erie"为例, 通过分析河流湖泊的水质特征, 针对伊利湖湖泊水质建立数学模型, 由于该环境系统为多输入多输出系统, 文章采用了一种改进的BP神经网络算法, 利用Matlab神经网络工具箱进行数据分析, 绘出实际输出与模型输出的曲线以分析相关情况, 检验建立的模型对于系统的辨识水平, 给出传统BP网络和改进BP网络对该系统辨识的结果进行分析对比. 文章还对不同噪声层次下的数据进行分析比较, 并研究白噪声对于人工神经网络模型的影响.     

Toward a classification of discourse patterns in asynchronous online discussions

The goal of this study was to develop a classification for a range of discourse patterns that occur in text-based asynchronous discussion forums, and that can aid in the distinction of three modes of discourse: knowledge sharing, knowledge construction, and knowledge building. The dataset was taken from Knowledge Forum® databases in the Knowledge Building Teacher Network in Hong Kong, and included three discussion views created for different classes: Grade 5 Science, Grade 10 Visual Arts, and Grade 10 Liberal Studies. We used a combination of qualitative coding and narrative analysis as well as teachers’ understanding of online discourse to analyze student discussions. Nine discourse patterns were identified. These patterns revealed a variety of ways in which students go about their collaborative interactions online and demonstrated how and why students succeed or fail in sustaining collaborative interactions. This study extended the three modes of online discourse and developed different discourse patterns, which are efforts to provide instructional guidance. The implications of supporting productive discourse and the enactment of CSCL innovations in classrooms are discussed.     

Iterative learning control for a class of mixed hyperbolic-parabolic distributed parameter systems

This paper deals with the problem of iterative learning control algorithm for a class of mixed distributed parameter systems. Here, the considered distributed parameter systems are composed of mixed hyperbolic-parabolic partial differential equations. The domain of the system is divided into two parts in which the system is hyperbolic and parabolic, respectively, with transmission conditions at the interface. According to the characteristics of the systems, iterative learning control laws are proposed for such mixed hyperbolic-parabolic distributed parameter systems based on P-type learning scheme. Using the contraction mapping method, it is shown that the scheme can guarantee the output tracking errors on L ² space converge along the iteration axis. A simulation example illustrates the effectiveness of the proposed method.     

卷扬式启闭机闸门闭落困难对策分析

水工闸门主要是用来泄水和挡水的,所以,需要经常开启和关闭闸门。对于螺杆式启闭机,严格按照规范操作正常操作闸门是不会出现问题的;对于卷扬式启闭机,虽然绳索可以传递拉力,但是,对压力完全没有影响。针对卷扬式启闭机闸门闭落困难的问题,积极采取有效的对策,确保卷扬式启闭机闸门可以正常闭落。简要分析了卷扬式启闭机闸门闭落困难的情况,阐述了相关的解决对策。     

An efficient bi-objective optimization framework for statistical chip-level yield analysis under parameter variations

With shrinking technology, the increase in variability of process, voltage, and temperature (PVT) parameters significantly impacts the yield analysis and optimization for chip designs. Previous yield estimation algorithms have been limited to predicting either timing or power yield. However, neglecting the correlation between power and delay will result in significant yield loss. Most of these approaches also suffer from high computational complexity and long runtime. We suggest a novel bi-objective optimization framework based on Chebyshev affine arithmetic (CAA) and the adaptive weighted sum (AWS) method. Both power and timing yield are set as objective functions in this framework. The two objectives are optimized simultaneously to maintain the correlation between them. The proposed method first predicts the guaranteed probability bounds for leakage and delay distributions under the assumption of arbitrary correlations. Then a power-delay bi-objective optimization model is formulated by computation of cumulative distribution function (CDF) bounds. Finally, the AWS method is applied for power-delay optimization to generate a well-distributed set of Pareto-optimal solutions. Experimental results on ISCAS benchmark circuits show that the proposed bi-objective framework is capable of providing sufficient trade-off information between power and timing yield.     

A study of optimal viewing distance in a parallax barrier 3D display

The optimal viewing distance was proposed as a parameter for designing a parallax barrier 3D display. It can be designed based on simple geometric method and by considering the pitches of image display pixels and parallax barrier, or even including the aperture ratios of the image display pixels and parallax barrier. It can be analyzed by using ray tracing method. By considering the optical refraction index of the cover glass, the angular behavior of the system becomes more realistic; however, the geometric method is difficult to be used. We propose a revised method for estimating the view distance and angular behavior. In this paper, we have demonstrated a designated eye position (DEP) for each view and shown that multiple DEPs make a circular curve around the center of the display. We prove the new concept by comparing the optical ray tracing calculations and optical measurement.     

Effect of Ce(3+) on soluble microbial products production in anaerobic granular sludge digestion

Upflow anaerobic sludge bed reactors fed on glucose were used to investigate the effects of Ce(3+) on soluble microbial products (SMP) production, which is the majority of the residual chemical oxygen demand present in the effluent. It was found that Ce(3+) concentration of 0.05 mg/L had no significant effect on the amount of SMP production, whereas that of 1 mg/L led to the increase in SMP production. The molecular-weight distribution and carbohydrate analysis indicated that an increase in SMP production may be partly attributed to the release of extracellular polymeric substances (EPS) into the bulk solution resulted from cerium toxicity, and the nucleic acids analysis suggested that increased cell lysis also contributed to SMP accumulation in the presence of Ce(3+). The increase in SMP production in the presence of Ce(3+) is possibly a consequence of the release of EPS and increased cell lysis due to cerium toxicity.     

杭州市清泰水厂膜处理自控系统方案比选

结合杭州市清泰水厂净水技术改造工程,介绍了膜处理自控系统的特点和要求,就三个膜处理自控系统方案进行了分析和总结。通过对比,选用了方案三,该方案实现了每一膜组的冗余热备控制,较好地达到了设计要求,可靠性高。     

A novel micro-fluidic biosensor for the rapid and sequence-specific detection of DNA with electrophoretic driving mode and laser-induced fluorescence detector

A novel DNA biosensor, which combines the merits of micro-fluidic chips, the electrophoretic driving mode, paramagnetic beads amplification, and laser-induced fluorescence detection was developed for the rapid and sequence-specific detection of DNA in this study. The proposed DNA biosensor has much higher discrimination ability for the detection of single-base mismatch and much stronger resistibility to the complex matrixes of real samples in comparison with previous biosensors. These features, as well as its ease of fabrication (the fabrication of the sensor takes only 10 min except the fabrication of micro-fluidic chip), operation convenience, stability, better re-usability (micro-fluidic chip can be reused without any extra treatment) and short analysis time (one determination only takes 15 min), make it a promising alternative to rapid detection of DNA in clinical diagnosis. With the help of the biosensor, we successfully determined DNA, which related to oral cancer, in a saliva sample without any pre-separation or dilution with a detection limit of 4.2 × 10^?11 M and a relative standard deviation (n = 5) <5 %. The success in the present biosensor served as a significant step toward the practical application of the biosensor in clinical diagnosis.