采用二元混合工质的脉管制冷机实验研究

首次在８０Ｋ温区脉管制冷机中采用混合工质进行了实验研究,实验结果表明,在其它运行参数不变的情况下,在氦氢二元混合工质中,当氢的摩尔浓度为２０％时,可获得比纯质氦高的制冷量。     

Application of High-Speed Laser Polarimetry to Noncontact Detection of Phase Transformations in Metals and Alloys at High Temperatures

A high-speed laser polarimetry technique, developed recently for the measurement of normal spectral emissivity of materials at high temperatures, was used to detect solid–solid and solid–liquid phase transformations in metals and alloys in millisecond-resolution pulse-heating experiments. Experiments were performed where normal spectral emissivity at 633 nm was measured simultaneously with surface radiance temperature, resistance, and/or voltage drop across the specimen. It was observed that a phase transformation, as indicated either by an arrest in the specimen radiance temperature or changes in the resistance and/or voltage drop, generally caused a change in normal spectral emissivity. Experiments were conducted on cobalt, iron, hafnium, titanium, and zirconium to detect solid–solid phase transformations. Similar experiments were also performed on niobium, titanium, and the alloy 85titanium–15molybdenum (mass%) to detect solid–liquid phase transformations (melting).     

新型推挽激励的谐振式微机械静电场传感器

为了提高传感器的信噪比(signal-to-noise ratio,SNR),降低器件的耦合干扰,基于表面微机械工艺设计制作了一种新型推挽激励方案的谐振式微型静电场传感器.该传感器敏感结构主要包括静电梳齿激励电极、屏蔽电极和感应电极3部分.工作时,在该传感器敏感结构同一侧梳齿的固定端上加入反相相等的激励信号,实现差分激励,使屏蔽电极在谐振频率处振动,从而在感应电极上感应出差分电流信号,通过相关检测方式检测出传感器该输出信号的二次谐波分量,即可获得被测静电场强度大小.该传感器的新型结构设计和激励检测方案可获得最大电场响应灵敏度,并有效抑制了同频耦合串扰和共模噪声.常压室温(约25℃)测试结果表明,在量程(-15 kV/m～15 kV/m)内,只需要5 Vpp激励电压,其中线性度(端基线性度)达到了1.03%,分辨率优于200 V/m.     

脉冲宽度对偏转电场法内表面等离子体浸没离子注入的影响

近年来 ,采用等离子体浸没离子注入 (PIII)对零部件内表面进行改性处理引起了各国研究工作者的广泛关注 .研究表明 ,提出的偏转电场法是进行内表面注入处理的有效方法 ,可以极大提高内表面注入的注入剂量和注入能量 .研究了采用偏转电场法注入时注入电压脉冲宽度对注入效果的影响 .结果表明 ,长注入脉宽可以提高内表面注入能量 ,但对注入剂量影响不大 ;脉冲宽度对注入峰值深度和注入剂量的分布有很大影响 ,长注入脉宽使注入峰值深度和注入剂量的最大值向筒内部移动 ;采用适当的不同宽度脉冲进行注入 ,可以改善注入均匀性 .     

矩形波冲击时瓦楞纸板衬垫破损边界曲线的研究

根据瓦楞纸板平压静态模型,建立了动力学方程.通过数值计算方法,研究瓦楞纸板在矩形波激励下的冲击响应,并讨论各参数对瓦楞纸板包装系统的冲击谱和破损边界的影响规律.     

高血压患者脉博信号的采集与频谱分析

根据人体脉博信号的特点,提出了一种对脉搏声信号进行检测和数据采集的方法。讨论了脉搏声信号采集和处理过程中各参数之间的关系及应选取的指标,介绍了脉搏信号的一种频域分析方法——功率谱分析,获得了两种脉搏信号的功率谱图。取检测对象１０８例,其中通过对６５例高血压患者、４３例健康人作为对照组的脉象信号的功率谱计算,发现高血压患者脉搏功率谱高频部分的能量分布较健康人发生了明显的变化,并从人体生理病理学的角度分析了变化的可能原因。得出了对高血压疾病的临床诊断有参考价值的结论     

微机脉冲电流电源装置的研制与应用

微机脉冲电流电源装置的电流脉冲频率连续可调,脉冲宽度可调,可以单脉冲输出,也可连续脉冲输出,大电流脉冲输出,输入参数可以随意设置,输出电流密度可变。该装置已用于非晶材料的处理当中,应用效果非常好。     

基于压力传感器的高精度血压计系统设计

血压是反映人体生理状况的一项重要指标,血压监测在临床和医疗保健中有着重要的地位。针对传统单片机设计方案测量精度不高、稳定性不好等缺点,采用MSP430单片机与ARM处理器有效结合的方法,设计了一种基于压力传感器的高精度血压计。从脉搏波特征点入手,采用了一种改进的阈值法,能准确检测出多种病理情况下的有效脉搏波峰值,该方法克服了传统阈值法检测脉搏波准确性不高的缺点,方法简单,测量时间短。采用自适应卡尔曼滤波算法拟合包络线,相比高斯曲线拟合效果更好,且易于编程实现。测试结果表明:系统误差小于4 mmHg,测量范围为0~295 mmHg,具有精度高、速度快的特点。     

Image copy-move forgery passive detection based on improved PCNN and self-selected sub-images

Image forgery detection remains a challenging problem. For the most common copy-move forgery detection, the robustness and accuracy of existing methods can still be further improved. To the best of our knowledge, we are the first to propose an image copy-move forgery passive detection method by combining the improved pulse coupled neural network (PCNN) and the self-selected sub-images. Our method has the following steps: First, contour detection is performed on the input color image, and bounding boxes are drawn to frame the contours to form suspected forgery sub-images. Second, by improving PCNN to perform feature extraction of sub-images, the feature invariance of rotation, scaling, noise adding, and so on can be achieved. Finally, the dual feature matching is used to match the features and locate the forgery regions. What's more, the self-selected sub-images can quickly obtain suspected forgery sub-images and lessen the workload of feature extraction, and the improved PCNN can extract image features with high robustness. Through experiments on the standard image forgery datasets CoMoFoD and CASIA, it is effectively verified that the robustness score and accuracy of proposed method are much higher than the current best method, which is a more efficient image copy-move forgery passive detection method.     

高空紫外火焰探测装置设计与应用

针对传统热电偶反应时间慢、测量精度低的问题,设计出一种灵敏度高的紫外线探测器,可以快速检测出火焰中释放的紫外线.通过GD-708紫外光敏管,将紫外线转换成脉冲串经光电隔离送至STM32处理器,并输出4～20 mA电流信号控制蒸汽阀的开度.此探测装置在检测火焰起燃、燃烧至熄灭过程中判断及时,既能延长点火器的使用寿命,又可减少点火的误报次数.测试结果表明:该装置具有反应灵敏,抗干扰能力强,输出稳定等优点,在工程场所得到广泛应用.