Control of thermally activated building systems (TABS) in intermittent operation with pulse width modulation

Thermally activated building systems (TABS) integrate the building structure as energy storage, and have proofed to be energy efficient and economic viable for the heating and cooling of buildings. Although TABS are increasingly used, in many cases control has remained an issue to be improved. In this paper, a method is outlined allowing for automated control of TABS in intermittent operation with pulse width modulation (PWM). This method represents one part of a TABS control solution with automatic switching between cooling and heating modes for variable comfort criteria which was published before. A first pulse width modulation control solution is derived based on a simple 1st order model of TABS. Then a second, even simpler solution is given that significantly reduces the tuning effort. Finally, the paper outlines a pulse width modulation control procedure and gives two application examples of the PWM control carried out in a laboratory test room.     

基于卡尔曼滤波的V形焊缝跟踪偏差修正

针对焊缝跟踪过程中存在多种噪声干扰、严重影响焊缝位置信息准确提取的现状,以碳钢平板对接为焊接试验对象,借助脉冲涡流无损检测提取焊缝位置峰值和过零时间;在此基础上,进一步采用卡尔曼滤波的系统状态最优估计方法,对焊接中心偏离状态进行修正。焊接试验结果表明:Kalman滤波算法能够有效消除多种噪声干扰,优化脉冲涡流提取信息,提高焊缝跟踪的稳定性。理论分析和实验结果相一致,验证了所采用方法的可行性。     

降低板材料表面白点亮点的方法

本文阐述了一种方法，适用于降低板材料表面的白点亮点问题，使板材料外观更加舒适。据考察，使用氢氧化铝无机填料与树脂制成板材后，由于氢氧化铝折光率与玻璃相近，在光照下，从某一角度看，板材表面会出现白点和亮点，影响板材料美观，特别是深色板材，尤为突出。本文主要介绍通过对氢氧化铝无机填料进行表面处理，从而达到降低其折光率的方法，来降低板材料表面的白点和亮点数量。     

PLC在粉体物料动态计量领域中的应用

描述颗粒细密压力较大的媒粉等粉体物料动态计量专用（转）子秤系统。系统使用西门子S7-200PLC为控制器,完成煤粉颗粒的动态计量与控制。     

Performance enhancements of compound semiconductor radiation detectors using digital pulse processing techniques

The potential benefits of using compound semiconductors for X-ray and gamma ray spectroscopy are already well known. Radiation detectors based on high atomic number and wide band gap compound semiconductors show high detection efficiency and good spectroscopic performance even at room temperature. Despite these appealing properties, incomplete charge collection is a critical issue. Generally, incomplete charge collection, mainly due to the poor transport properties of the holes, produces energy resolution worsening and the well known hole tailing in the measured spectra. In this work, we present a digital pulse processing (DPP) system for high resolution spectroscopy with compound semiconductor radiation detectors. The DPP method, implemented on a PC platform, performs a height and shape analysis of the detector pulses (preamplifier output pulses), digitized by a 14-bit, 100 MHz ADC. Fast and slow shaping, automatic pole-zero adjustment, baseline restoration and pile-up rejection allow precise pulse height measurements both at low and high counting rate environments. Pulse shape analysis techniques (pulse shape discrimination, linear and nonlinear pulse shape corrections) to compensate for incomplete charge collection were also implemented. The results of spectroscopic measurements on a planar CdTe detector show the high potentialities of the system, obtaining low tailing in the measured spectra and energy resolution quite close to the theoretical limit. High-rate measurements (up to 820 kcps) exhibit the excellent performance of the pulse height analysis and the benefits of pulse shape techniques for peak pile-up reduction in the measured spectra. This work was carried out in the framework of the development of portable X-ray spectrometers for both laboratory research and medical applications.     

Effect of Fluence and Pulse Overlapping on Fabrication of Microchannels in PMMA/PDMS Via UV Laser Micromachining: Modeling and Experimentation

This article presents modeling and experimental investigations on the effects of process parameters and the viability of directly fabricating microchannels in polymethyl methacrylate (PMMA) and polydimethylsiloxane (PDMS) polymers which are suitable for the fabrication of microfluidic devices due to their biocompatibility and transparent properties. Experimental work was conducted using a solid-state Nd:YAG laser with 355 nm ultraviolet (UV) wavelength and 5 ns pulse duration at various energy densities and pulse overlapping (PO). The study was focused on understanding the effects of two main process parameters: fluence and PO. This study closely investigates the effect of varying process parameters on the ablation depth and profile achieved and the resultant microchannel dimensional quality. It presents findings indicating that both process parameters have strong effects on the profile shape and variability of the microchannel width and depth. For PMMA polymer, the lowest dimensional variability for the microchannel profile is obtained with low fluence values and highest PO factor, whereas for PDMS polymer, it was observed that microchannel width and depth decreased linearly with increasing fluence and increased nonlinearly with increasing scanning rate. Further, process modeling is utilized for predicting microchannel profile and ablation depth, and these predictions were validated with experimental results obtained with pulsed laser micromachining at UV wavelength.     

车辆迫停系统发展研究

射频迫停系统是一种用于车辆或快艇拒止的强电磁脉冲武器，主要由初级电源、脉冲功率源、微波发生器和 宽带辐射天线。文中作者分析了射频迫停系统的应用需求和国内外发展现状，深入研究了射频迫停系统的总体组成和 关键技术。     

基于PDM的LED背光调亮技术研究

为解决PWM(Pulse Width Modulation)背光调亮技术的应用缺陷,提出了一种基于脉冲密度调制(PDM:Pulse Density Modulation)的背光调亮算法。对PWM和PDM调亮波形进行了频域仿真分析,结果表明PDM的谐波被移到频率更高的位置,避开了电源传导发射试验CE101的测试频段(25 Hz^10 kHz)的范围,从而更容易满足电磁兼容要求。对某产品分别采用PWM和PDM调亮技术进行CE101和负载特性对比测试,测试结果表明:与PWM调亮技术相比,PDM调亮技术的电源电流波形比较平缓,不会跟随调制脉冲出现剧烈的振荡,负载特性具有明显的改善。基于PDM的LED背光调亮技术优势明显,更适合应用在电磁环境复杂、负载特性敏感的领域。     

Electrochemical oxidation of phenol at boron-doped diamond electrode in pulse current mode

In this study, a pulse current supply was initially used in a BDD anode system (pulse-BDD anode system) for electrochemical oxidation of phenol. The influences of operative parameters (current density, retention time, pulse duty cycle, power frequency) on the system performances were exmamined by response surface methodology (RSM). As for COD degradation efficiency (D_COD) and specific energy consumption (E_s), the influence of retention time was more important than current density and pulse duty cycle, while power frequency hardly presented significant influence. By the comparison with constant current mode, an obvious specific energy consumption reduction was achieved in the pulse-BDD anode system, though the D_COD was slightly lower. The significant E_s decrease might be attributed to the reduction of side reactions and concentration polarization in pulse current mode. The pulse-BDD anode system demonstrated an efficient technology to simultaneously obtain high pollutant degradation efficiency and low energy consumption.     

石灰出库自动除尘系统的改进

石灰在出库过程中,通过光电开关感应使通风除尘电机自动变频启动,含尘气体在引风机负压的作用下被布袋统一收集,收集后的灰粉进入集灰斗,通过螺旋输送机排入提升机,实现了除尘系统的自动变频启动和灰粉的回收、利用,降低了烟尘的排放浓度。