用于热气体过滤的改进纤维

<正> 1 引言 众所周知,为清洁空气对汽车尾气排放立法,竞争迫使汽车公司研究降低汽车有害气体排放的技术,其中从汽车尾气中将固体粒子过滤分离是关键技术。从60年代初开发芳香族酰胺纤维Nomex~((R))和70年代开发Teflon~((R))PTFE纤维开始,杜邦公司一直致力于发展控制污染和回收产品用的耐高温(>150℃)过滤介质,以满足特殊用户的需求。虽然原先的芳香族聚酞胺纤维(2.2dtex)和 PTFE纤维(7.4 dtex)的性能可满足多种应用的需要,但客户有时发现传统基布问题的解决办法(例如提高毡的基本重量、涂层、薄膜)既不能满足新的要求,又会产生一些难以接受的负效应(如压降高、寿命短)。多年来,为了满足在高     

JB—N2.5F型超高压径向柱塞泵简介

工作压力在500公斤/厘米~2以上的液压传动,可称为超高压传动。要获得如此高的液体压力,目前有两种方法。(1)直接式:用超高压泵直接向系统供油;(2)增压式:通过增压器,将一次压力增至所需压力。从目前国内外技术发展水平来分析,在500～1000公斤/厘米~2压力范围内,采用直接传动式的优点越来越明显。在一些设备中,有取代增压式的趋势。在机器制造行业中,锻压机械、煤矿机械、建筑施工机械及超高压液压机具等,都迫切需要不同压力级、不同流量规格的超高压油     

熔喷非织造布产品与技术经济分析

介绍了熔喷非织造布生产原理、产品用途,并对熔喷生产线进行了技术经济分析.     

给你的Blog加一个时钟

俗话说时间就是金钱,但是一旦上网维护自己Blog的时候,时间就不知不觉从身边溜走。如果能在自己的Blog上加一个小时钟多好呀。Clocklink.com就是提供这个服务的网站,只要生成一段简单的代码放入你的Blog,就可     

Thresholds for inertial cavitation in albunex suspensions under pulsed ultrasound conditions

Stabilized microbubbles used as echo-contrast agents can be destroyed by ultrasonic irradiation. We have identified two pressure thresholds at which these microbubbles undergo inertial cavitation (here, defined as the collapse of gas bubbles followed by emission of an acoustic broadband noise). The first threshold (P1) corresponds to the pressure at which all the microbubbles in a cavitation field lose their property as an effective scatterer because of fragmentation or deflation. The second threshold (P2) is associated with the acoustic reactivation of the remnants of the contrast agents and is related to the onset of more violent inertial cavitation. P1 and P2 were measured as a function of the concentration of Albunex(R) (Molecular Biosystems Inc., San Diego, CA) contrast agent, the number of transmitting acoustic cycles, and the pulse repetition frequency (PRF). The ultrasound frequency used was 1.1 MHz, and the peak negative acoustic pressures ranged from 0 to 8 MPa. Our results, measured in Isoton(R) II (Coulter Diagnostics, Miami, FL) and whole blood solutions, showed that P1 increased with increasing Albunex(R) concentration and decreased with increasing PRF, whereas P2 decreased with increasing Albunex(R) concentration and was independent of the PRF. Both P1 and P2 decreased with increasing number of acoustic cycles N for N<10 and were independent of the number of cycles for N>10. Ultrasound images of Albunex(R) acquired by a commercial scanner showed echo enhancement not only at pressure levels below P1 but also at levels above P2. The threshold P2 was achieved at ultrasound energies above the diagnostic level. Inertial cavitation produced at P2 was associated with a higher level of hemolysis compared with P1. The results of this investigation have potential significance for both diagnostic and therapeutic ultrasound applications     

Edge enhancement and edge-enhanced correlation with photorefractive polymers

We demonstrate a simple all-optical realization of programmable edge enhancement and edge-enhanced correlation using novel photorefractive polymers. We show that the higher non-Bragg order in a two-beam coupling scheme contains the edge enhancement of the object when placed in the path of one of the incident beams. Also, this arrangement provides a scheme for writing joint transform correlation dynamic holograms, which can be read by a third beam. The correlation is edge enhanced, and the correlation peak increases with the applied bias voltage. Numerical results without and with beam fanning are presented. Theoretical predictions are reconciled with experimental results.     

Decomposition of posterior alpha rhythm

The classical posterior alpha rhythm has been decomposed into regular and irregular components using orthogonal transformation. A periodicity generator is considered, which has three characteristic control parameters: the periodicity, the amplitudes or scaling factors and the pattern associated with successive periodic segments. The regular component is shown to be equivalent to an oscillator or periodicity generator whose parameters are dynamically varying and, thus, producing both amplitude- and frequency-modulation. The irregular component is devoid of such modulating behavior. Electroencephalogram signals from normal, maniac and epileptic subjects are studied. Through analytic signal-based analysis, it is shown that for the regular component, healthy brain possesses universal scaling behavior, whereas heterogeneous scaling or absence of universality is observed for the diseased brain.