火灾自动报警系统在设计中的应用探讨

探讨火灾自动报警系统设计在实际工程中碰到的几个问题。分析高举架、大空间场合下探测器的选择,防爆区模块的安装,非消防电源的切断以及手动报警按钮的设置等问题。     

臭氧气氛下LED灯光对银质文物模拟材料腐蚀变色的影响

目的研究臭氧与LED灯光共同作用于银质文物模拟材料的腐蚀行为和规律。方法采用石英晶体微天平(QCM)反应性监测及SEM-EDS等方法,研究了暴露于臭氧和LED灯下的银质文物模拟材料的腐蚀行为及其表面特征。结果暴露于LED灯或臭氧条件下的石英晶振片频率均有所下降,而暴露于LED灯加臭氧复合条件下的石英晶振片频率下降速率更快且最终下降值更多。此外,升高LED灯色温、增大臭氧浓度或提高环境温度,均会使石英晶振片频率下降速率更快且最终下降值更大。在臭氧质量浓度为5μg/L环境中,与无光照条件相比,LED光照下的银片表面的腐蚀产物及氧元素含量较多,并且LED灯的色温越高,其光照下的银片表面生成的腐蚀产物越多,但不同品牌的LED灯下的银片表面腐蚀产物生成量及氧元素含量均相近。结论臭氧与LED灯光均会加速银的腐蚀,两者共同作用时,会使银腐蚀更严重。升高LED灯色温、增加臭氧浓度或提升环境温度也同样会加速银的腐蚀,但不同品牌LED灯对银腐蚀的影响却相差无几。     

基于粒子群算法的大模数齿轮冷挤压变过盈量组合凹模优化设计

针对大模数圆柱直齿轮冷挤压过程中均匀过盈量组合凹模易出现开裂的问题,提出一种变过盈量组合凹模的设计方法,并以直径比、中圈内壁锥角和过盈系数为设计变量,以降低模芯内壁等效应力、避免模芯出现周向拉应力和避免内外圈塑性变形为优化目标,建立变过盈量组合凹模结构参数与综合加权评分值的Kriging模型。应用Kriging模型结合粒子群算法,在可行变量空间内寻优,得到最优工艺参数组合为:n_2=1.55,n_3=2.55,γ'=1.25°,β_2=2.5‰,β_3=2.4‰。研究结果表明,采用优化后的变过盈量组合凹模可有效避免组合凹模的破裂,提高模具的使用寿命。     

双驱双向AGV控制系统设计

以工业平板电脑+可编程多轴控制器(PMAC)构成开放式控制器硬件系统,采用面向对象的C++程序设计语言进行上位机控制系统软件开发。根据技术要求进行系统功能需求分析,采用模块化的思想,设计系统软件总体结构;介绍了导航模块纠偏算法的实现。最后以双驱动双向AGV为机械本体进行停车定位测试。结果表明:该AGV的平均定位精度为5.144 mm,最大的定位精度为9.232 mm,其精度满足要求,该控制系统软件较好地完成了导航定位任务。     

Inlet plenum pressure drop calculation for a cross-flow module

Outlined here is a method for applying a model of discharge flow through a series of sharp-edged orifices from an inlet plenum, to accurately predict the total pressure drop across the flow distribution geometry. This particular case relates to a cross-flow filtration membrane module, but is applicable for any flow distribution system of a similar format.     

Development of a practical foolproof system using ultrasonic local positioning

The objective of this research is to develop a prototype for practical foolproof system which can be used in manual assembly processes. For this purpose, a high-performance and low-cost ultrasonic system is proposed to measure 3D positions of an indoor mobile object. Composed of an ultrasonic sender and a receiver, the system employs ultrasonic time-of-flight (TOF) and trilateration to estimate the positions of the object with an accuracy of few centimeters. To calculate three TOFs, ultrasonic signals are processed full-digitally with a low-cost FPGA, which provides high design flexibility keeping both high performance and low noise. Proposed system is autonomous, so there is no need of an external PC and the system development cost becomes low. As an improved thresholding method to calculate the TOFs, this paper proposes a debounce module, designed in the FPGA, to remove the pulse noises generated during the thresholding. The resulting time delay from the debounce is compensated by a microprocessor for calculating actual TOFs. Lastly, the positions of the mobile object are calculated from the TOFs values by trilateration in the microprocessor. In order to remove measurement noises, both moving average filters and Kalman filters are adopted in calculating the TOFs and positions.     

汽车天窗的发展历史及新技术应用

介绍汽车天窗的发展历史、基本类型、基本构成和一些新技术,以及在未来几年的发展前景。     

Optoelectronic sensor device for monitoring the maceration of red wine: Design issues and validation

Enologists usually rely on spectrophotometers to perform the chromatic characterization of red wines. This work reports an optoelectronic instrument based on absorbance measurements aiming not only at the assessment of the chromatic characteristics of finished red wines, but at the supervision of the gradual maceration of fermenting grape musts as well. Maceration is a chemical process that takes place during the early stages of the fermentation that finally results in red wine. It is through maceration that wine acquires its distinctive chromatic features. Key issues related to the selection of optoelectronic components, the system design and its final validation using diluted wine samples are thoroughly discussed. Resolution figures lie in the range of one thousandth of an absorbance unit. Maceration has been successfully monitored with the proposed instrument using grape must samples extracted during the first three days from two different fermentations.     

Si IGBT/SiC MOSFET混合器件及其应用研究

综述了Si IGBT/SiC MOSFET混合器件在门极优化控制策略、集成驱动设计、热电耦合损耗模型、芯片尺寸配比优化和混合功率模块研制等方面的最新研究成果与进展。Si IGBT/SiC MOSFET混合器件结合了SiC MOSFET的高开关频率、低开关损耗特性和Si IGBT的大载流能力和低成本优势,已有文献的最新研究和实验结果验证了该类器件的优异特性,表明其对高性能电力电子器件实现更高电流容量、更高开关频率和较低成本具有重要意义,是高性能变换器应用中非常有潜力的功率器件类型。     

扩展接触器零部件通用性的研究

本文介绍了一种只用十几个分立元件的电子模块，与大型接触器配合使用，可使接触器节省铜线材料60％～70％，大大减少电磁系统的体积。预置电子模块的参数，可实现交流接触器在起动过程、吸持过程的最佳电流控制，为扩展接触器零部件通用性研制出节能、节材、无噪声等性能优良的小型而容易实施的交流接触器产品提供了依据。