CuO/ZnO甲醇合成催化剂的正电子湮没谱学研究

发展了用正电子湮没寿命参数测定用共沉淀方法制备的金属氧化物系固溶度的新方法。测量了一系列用共沉淀方法制备的不同CuO at％含量的CuO/ZnO甲醇合成催化剂粉末(压制成片)还原前后的正电子寿命谱。分析该种催化剂的固溶特性及其与正电子寿命参数的关系,得出还原后样品的固溶度为12CuOat％.支持了CuO/ZnO甲醇合成催化剂以Cu~+离子为活性中心的观点。     

Improving signal prediction performance of neural networks through multiresolution learning approach.

In this paper, we extend the original work on multiresolution learning for neural networks, and present new developments on the multiresolution learning paradigm. The contributions of this paper include: (1) proposing a new concept and method of adjustable neural activation functions in multiresolution learning to improve neural network learning efficacy and generalization performance for signal predictions; (2) providing new insightful explanations for the multiresolution learning paradigm from a multiresolution optimization perspective; (3) exploring underlying ideas why the multiresolution learning scheme associated with adjustable activation functions would be more appropriate for the multiresolution learning paradigm; and (4) providing rigorous validations to evaluate the multiresolution learning paradigm with adjustable activation functions and comparing it with the schemes of multiresolution learning with fixed activation functions and traditional learning. This paper presents systematically new analytical and experimental results on the multiresolution learning approach for training an individual neural network model, demonstrates our integral solution on neural network learning efficacy, and illustrates the significant improvements on neural networks' generalization performance and robustness for nonlinear signal predictions.     

葛洲坝水力发电厂自动化技术应用概述

以葛洲坝水力发电厂主要自动化技术应用与设备改造为线索，重点回顾 了该厂实现计算机实时监控、全面提高综合自动化水平的历程；全面总结了该厂为实现“无 人值班”（少人值守）而进行的自动化设备换型改造情况和自动化新技术的应用情况；简要 阐述了自动化技术应用给该厂在运行和管理方面带来的深刻变化；展望了该厂未来自动化技 术应用的前景。     

熔融-固相缩聚法中固相聚合对聚乳酸合成的影响

以L 乳酸单体为原料 ,熔融 -固相缩聚法合成了聚乳酸 ,重点研究了固相聚合的工艺条件。结果表明 ,绝对压力 60Pa ,氯化亚锡为催化剂 ,分段控温 ,可使聚乳酸的粘均分子量提高到固相聚合反应前的 5 3倍。通过对固相聚合产物的结晶度和熔点的分析 ,探讨了固相聚合的机理。     

Single-longitudinal-mode fiber ring laser employing an equivalent phase-shifted fiber Bragg grating

A novel single-longitudinal-mode (SLM) fiber ring laser that incorporates an equivalent phase-shifted fiber Bragg grating acting as an ultra-narrow bandpass filter in the laser cavity is proposed. The equivalent phase-shifted fiber Bragg grating has an ultra-narrow transmission bandwidth which ensures an SLM lasing. Stable SLM operation without mode hopping is demonstrated.     

Group-blind intersymbol multiuser detection for downlink CDMA with multipath

Group-blind multiuser detectors for uplink code-division multiple-access (CDMA) were recently developed by Wang and Host-Madsen. These detectors make use of the spreading sequences of known users to construct a group constraint to suppress the intracell interference. However, such techniques demand the estimation of the multipath channels and the delays of the known users. In this paper, several improved blind linear detectors are developed for CDMA in fading multipath channels. The proposed detectors utilize the correlation information between consecutively received signals to generate the corresponding group constraint. It is shown that by incorporating this group constraint, the proposed detectors can provide different performance gains in both uplink and downlink environments. Compared with the previously reported group-blind detectors, our new methods only need to estimate the multipath channel of the desired user and do not require the channel estimation of other users. Simulation results demonstrate that the proposed detectors outperform the conventional blind linear multiuser detectors.     

常用小水电工程地面控制测量方法

测量工作在小水电工程建设中起着重要的作用。小水电工程按其布置的方式分为堤坝式、引水式和混合式三种。堤坝式电站的测量工作比较简单,而引水式和混合式电站是高水头式,这类电站传统的地面控制测量方法是建立小三角网,但目前由于GPS和全站仪的全面普及,传统的小三角网控制已完全被GPS测量或与EDM导线结合的方法所代替。文章着重介绍引水式或混合式高水头小水电工程的地面控制测量。     

DSP技术在声强测试系统中的应用

根据声强测试过程中对数据处理系统的需求,提出了以数字信号处理器(DSP)TMS320C5409与A/D转换器芯片MAX125为核心构建高速多通道声强数据采集处理系统的方案,并结合它们的特点对该方案进行了论证.同时,详细介绍了TMS320C5409与MAX125之间的硬件接口电路的设计和软件编程的方法.实验表明,该数据采集处理系统具有速度快、可靠性高、结构简单等特点,满足声强测试过程的技术要求.     

Time dependent crystal-smectic transformation in perylene-containing polyimides

The crystalline conformations of perylene polyimides (PPIs), with alkyl spacers varying in length from C₃ to C₁₂ are discussed. Although modeling of single chains would suggest the possibility that those with odd number of CH₂ groups adopt a flat helical shape, X-ray diffraction suggests that the chains with odd and even spacers have the same conformation, due to the necessity to pack the perylene units. Upon annealing, the UV-vis absorption maximum red-shifts by about 10 nm, indicating enhanced π-stacking between the perylenes. Several changes in the spectra are seen with an increase in annealing time, at a given temperature. With an increase in annealing time, X-ray diffraction patterns show changes in the number of reflections, indicative of a crystal to mesogenic transition. The time required for this transition increases with a decrease in the spacer length, and annealing temperature, suggesting that the dynamics of this transition is very slow.