次声信号产生机理与特性分析

次声监测技术是《全面禁止核试验条约》规定的四种监测技术手段之一,用来监测大气层中的核爆炸。根据次声台站监测过程中经常需要分析处理的次声信号类别,着重介绍分析爆炸、火山喷发、地震等令人震撼的事件以及微气压、海浪等日常司空见惯的自然现象激发次声波的机理及其信号特征。这些特征对于次声监测数据处理、去噪降噪、目标分类与识别等具有重要意义。     

次声实验系统及其声学性能分析

为了从环境保护和劳动卫生学的角度研究次声对人的影响 ,本研究基于亥姆霍兹谐振器的基本原理研制了一个次声试验系统。该系统由亥姆霍兹谐振器、电声驱动部分和测控分析部分组成 ,通过对该系统的声学性能进行测试和分析 ,确定了系统所能发出的次声频率和次声级范围 ,讨论了系统发出次声时所产生的高次谐波对系统性能的影响及系统的频响特性 ,检验了谐振腔内部次声场空间分布的均匀性 ,结果表明该系统的声学性能是令人满意的 ,能够满足研究次声及其对人影响的实验要求。     

互相关算法在次声监测数据处理中的应用

次声监测数据处理技术是我国履行全面禁止核试验条约必备技术之一。重点介绍逐次多通道互相关(PMCC)算法原理、处理流程以及与之相关的数据处理系统,并利用典型次声事件进行了实验研究。结果表明PMCC在处理次声监测数据方面具有优异性能。     

“西电东送”贵州火电项目对区域PM10污染的影响

以贵州省为中心的"西电东送"南部通道(20°N～33°N,97°E～118°E)为研究区域,分别对该区域2004(现状年)和2010年(规划年)的PM10污染情况进行模拟和预测.分析了该区域现状年与规划年2个时段的PM10污染空间分布特征,对比了原生和次生PM10的贡献,指出造成该区域PM10污染的主要原因.结果表明:研究区域内PM10污染主要由次生PM10造成,而次生PM10主要是由二氧化硫反应生成的硫酸盐颗粒物.因此,对于贵州火电规划项目而言,减轻区域PM10污染须减排二氧化硫.     

深刻吸取海上事故教训进一步提升海上安全管理水平

分析了英国BP公司"4.20"爆炸沉船事故、胜利油田作业三号平台"9.7"倾覆事故、康菲公司蓬莱19-3油田海底溢油等3起事故原因及应吸取的教训,提出了主要防范措施。     

光释光(OSL)测年技术的初步实验研究

提出了基于X射线激发的光释光测年原理，据此进行了初步实验研究。研究表明，利用X射线是可以激发辐射样品使其产生光释光信号的。     

岩溶区峰丛洼地植被指数的克里格分析

为了全面掌握岩溶区峰丛洼地植被指数(NDVI)的空间分布状况,解决岩溶区峰丛洼地遥感影像山体阴影区域NDVI信息"缺失"的问题,对广西平果县果化生态重建示范区内的典型峰丛洼地非阴影区域NDVI进行了提取.利用地统计学的方法对NDVI的空间结构特征进行了分析,并对山体阴影区的NDVI进行了预测与验证.结果表明,研究区域NDVI主要受到内在因子的作用,具有强烈的空间自相关性,自相关距离为300 m;Kriging插值结果表明,研究区域NDVI的均值为0.196,在空间分布上表现为条带状和斑块状分布,NDVI高值区域主要分布在峰丛坡度>25°的山体区域,低值区域主要分布在峰丛坡度<25°的山脚和洼地等区域;Kriging插值验证结果表明,研究区域NDVI具有非常高的预测精度,能很好地估计山体阴影区NDVI,为岩溶区生态环境监控、石漠化评估提供了新的思路与方法.     

环境卫星大解密

2008年9月6日11时25分7秒,太原卫星发射基地,伴随着巨大的轰鸣声,一颗火箭正飞速上升.而它所运载的卫星,正是我国环保工作者梦想了十年,可对环境污染、生态破坏和自然灾害进行大范围、全夫候、全天的动态监测的环境卫星——"环境一号".作为我国首次发射的环境和减灾卫星,"环境-号"是我国目前民用卫星中技术最复杂、指标最先进的对地观测系统之一.那么,这颗环境卫星背后到底隐藏着怎样的秘密呢?     

火箭整流罩抗碎片侵彻能力的数值模拟

为研究火箭整流罩对箭上有效载荷的防护性能,以某型液体运载火箭为分析对象,利用Autodyn软件对火箭爆炸碎片撞击有效载荷整流罩的过程进行了数值模拟,分析了碎片撞击速度和撞击倾角对整流罩抗碎片侵彻能力的影响。数值计算结果表明:碎片的撞击速度和撞击倾角是影响火箭整流罩抗碎片侵彻能力的重要因素,对碎片本身形变也有一定的影响;侵彻时间随碎片撞击速度呈单调递减,当碎片撞击速度较小时,碎片撞击造成的速度损失与撞击速度呈正相关;有效载荷整流罩抗侵彻能力随碎片撞击倾角的增大而增强,侵彻时间随碎片撞击倾角的增大呈单调递增。数值模拟结果与理论计算结果基本吻合,表明该数值计算模型能较好地模拟火箭爆炸碎片撞击有效载荷整流罩的过程。     

ALOHA软件在氯乙烯泄漏事故中的应用与分析

以某化工厂氯乙烯泄漏事故为背景,通过ALOHA软件对事故影响范围进行分析。对有毒气体扩散、蒸气云爆炸以及沸腾液体扩展蒸气云爆炸的事故影响范围进行模拟,利用Google Earth在地图中拟合泄漏事故危害范围。结果表明:有毒气体扩散事故中,一级致毒区域、二级致毒区域和三级致毒区的范围分别为下风侧1 000～2 500 m、483～1 000 m和483 m;蒸气云爆炸事故热辐射影响第1警戒线和第2警戒线区域面积分别约为231 m×200 m、561 m×280 m,第3警戒线内氯乙烯浓度低且爆炸事故概率较小;蒸气云爆炸冲击波红色警戒线、橙色警戒线和黄色警戒线内半径分别约为214 m、298 m、621 m;对于沸腾液体扩展蒸气云爆炸事故,氯乙烯泄漏储罐周围800 m内的人员接触热辐射后有致命危险,可能造成人员烧伤的事故范围为1 100 m,在2 000 m范围内人员接触热辐射60 s会产生疼痛感。     

光纤传输在地震台信号传输中的应用

深圳地震台处于强雷电干扰地区,雷电干扰的破坏给深圳地震台的各类设备带来严重的损害,造成较大的经济损失,后来在信号传输线路上改用了光纤传输,起到了明显的效果。作者将深圳台在应用光纤传输地震信号的实践工作进行简要总结,供一线台站的同行参考。     

光纤传输在地震台信号传输中的应用

深圳地震台处于强雷电干扰地区，雷电干扰的破坏给深圳地震台的各类设备带来严重的损害，造成较大的经济损失，后来在信号传输线路上改用了光纤传输，起到了明显的效果。作者将深圳台在应用光纤传输地震信号的实践工作进行简要总结，供一线台站的同行参考。     

Survival of Porcine Reproductive and Respiratory Syndrome Virus in Pork Products

There is a risk of virus transmission through contaminated pork, and many viruses are considered potential hazards for both humans and livestock. The risk of transmission may be elevated with importation/exportation of meat between countries globally. Survival of porcine reproductive and respiratory syndrome virus (PRRSV) in different pork products has not been studied. The present study evaluated PRRSV survival in four different products: fresh sausage, ham, bacon, and acidified sausage prepared with experimentally contaminated pork. These products were prepared according to standard methods used by the manufacturers of pork products, and then stored at room temperature, 4 °C and ?20 °C. PRRSV was detected only in fresh sausage for up to 15 days at 4 °C and for 30 days at ?20 °C. No PRRSV was detected at any temperature in any of the other three products. These preliminary data provide valuable information for the pork processing industry, as well as in planning for import/export of these products among different countries.     

Preparation and microwave absorbing properties of the core-nanoshell composite absorbers with the magnetic fly-ash hollow cenosphere as core

Electromagnetic (EM) wave pollution has become the chief physical pollution for environment. The core-nanoshell composite absorbers with magnetic fly-ash hollow cenosphere as core and nanocrystalline magnetic material as shell were prepared by high-energy ball milling. The results of X-ray diffraction analysis (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and vector network analyzer (VNA) analysis indicated that perfect-crystalline nanomagnetic material coating was gotten with a particle size of 12 nm, being dried at 60°C for 2 hr and calcined at 400°C for 1 hr after ball milling. The exchange-coupling interaction happened between ferrite of cenosphere and soft magnet γ-Fe₂03 coating, it enhances magnetic loss of composite absorbers. In the frequency between 1 MHz and 1 GHz, the absorbing effectiveness of the core-nanoshell composite absorbers can achieve ?30 dB, it is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption.     

Beeping and piping: characterization of two mechano-acoustic signals used by honey bees in swarming

Of the many signals used by honey bees during the process of swarming, two of them??the stop signal and the worker piping signal??are not easily distinguished for both are mechano-acoustic signals produced by scout bees who press their bodies against other bees while vibrating their wing muscles. To clarify the acoustic differences between these two signals, we recorded both signals from the same swarm and at the same time, and compared them in terms of signal duration, fundamental frequency, and frequency modulation. Stop signals and worker piping signals differ in all three variables: duration, 174?±?64 vs. 602?±?377?ms; fundamental frequency, 407 vs. 451?Hz; and frequency modulation, absent vs. present. While it remains unclear which differences the bees use to distinguish the two signals, it is clear that they do so for the signals have opposite effects. Stop signals cause inhibition of actively dancing scout bees whereas piping signals cause excitation of quietly resting non-scout bees.     

船载CCTV海洋环境实时监控系统设计研究

船载式监控系统通常是地面监控系统的衍生品,在海洋的环境下存在信号阻隔以及监控传输缓慢的现象,并且传输过程没有报警系统,针对上述问题,设计一套在船载CCTV海洋环境下的实时监控系统.选用BMG-COZ-NDIR传感器减少来自海洋环境对监控质量的影响,MSP430F149型号微处理芯片处理监控数据时能够分析出异常数据,并发出报警信号,重新修订传感器信号数据压缩编码,完成实时监控指令,设置报警传输编码,执行报警命令.通过编码信令的搭配实现船载海洋环境下的实时监控.通过设计仿真实验得到结论:(1)设计的船载CCTV海洋环境下实时监控系统在海洋环境下能够保持无阻隔的实时监控;(2)实时监控数据的传输质量以及传输效率优于传统监控系统;(3)对异常数据发出警示.     

Insertable thin film thermocouples for in situ transient temperature monitoring in ultrasonic metal welding of battery tabs

Real-time monitoring and control of temperature in ultrasonic joining of battery tabs and coupons are important for the quality improvement and cost reduction of battery assembly. However, there have always been difficulties in accurate and real-time measurement of temperature by conventional sensors for practical implementation. In this study, an innovative method is developed to provide an enabling technology for the in situ transient temperature monitoring, which could provide reliable feedback signals for potential control of ultrasonic joining processes. Micro thin film thermocouples (TFTCs) were fabricated on thin silicon substrates, which were then inserted in the welding anvil as a permanent feature so that the sensors were always located about 100 μm directly under the welding spot during joining of multilayer Ni-coated Cu thin sheets for battery assembly. Good repeatability was demonstrated while a temperature rise of up to 650 °C was obtained due to the closeness of the sensors to the welding spot. The inserts with thin film sensors remained functional after welding experiments. This method has a great potential for in situ transient temperature monitoring, and thus the control of ultrasonic joining processes to realize a practical smart joining system.