An Experimental Study of Indoor and Outdoor Concentrations of Fine Particles Through Nonisothermal Cracks

It has been shown that a substantial proportion of indoor exposure is from particles originating outdoors. Idealized cracks have been used to study penetration under laboratory settings and all previous studies assumed isothermal conditions. There can be 10–20°C difference between indoor and outdoor temperatures even in mild climate zones. This is the first study to investigate the influence of thermophoresis on the penetration of particles through cracks. A sandwich design consisting of two chambers (each 0.325 [W] × 0.125 [L] × 0.11 [H] m³) and a crack module was used to measure indoor-to-outdoor particle concentrations under practical indoor and outdoor conditions. An idealized aluminum smooth crack of 90 mm crack length was tested under three different pressures ranging from 4 to 8 Pa. Submicron sodium chloride particles were generated and a scanning mobility particle sizer was used to scan the concentration in outdoor and indoor chambers. To mimic summer and winter conditions in temperate climatic zones, two sets of temperature differences (indoor–outdoor) were used: +18°C and ?10°C. I/O ratio and relative difference of I/O ratio compared to the isothermal condition were calculated. Inferring from the results, it can be observed that the I/O ratios under the winter scenario are substantially higher than those under the summer and isothermal scenarios for particle sizes less than 100 nm and the influence of temperature on I/O ratios diminishes with increasing particle sizes.

Copyright 2013 American Association for Aerosol Research     

An Interleaved AC–DC Converter Based on Current Tracking

In this paper, an interleaved AC-DC converter based on current tracking without any current sharing required is presented and applied to a two-phase flyback converter. This is realized using two critical-conduction-mode (CRM) pulsewidth-modulated chips, together with a field-programmable gate array technique. By doing so, not only are the total harmonic distortion and the power factor improved but the output power is also upgraded. In this paper, the circuit operation is described in detail, with some experimental results given to verify the proposed control scheme.     

A new sustainable hydrogen clean energy paradigm

We analyze the feasibility of a novel, hydrogen fuel cell electric generator to provide power with zero noise and emissions for myriad ground based applications. The hydrogen fuel cell electric generator utilizes a novel, scalable apparatus that safely generates hydrogen (H₂) on demand according to a novel method, using a controlled chemical reaction between water (H₂O) and sodium (Na) metal that yields hydrogen gas of sufficient purity for direct use in fuel cells without risk of contaminating sensitive catalysts. The sodium hydroxide (NaOH) byproduct of the hydrogen producing reaction, is collected within the apparatus for later reprocessing by electrolysis, to recover the Na reactant. The detailed analysis shows that the novel, hydrogen fuel cell electric generator will be capable of meeting the clean power requirements for residential and commercial buildings including single family homes and light commercial establishments under a wide range of geographic and climatic conditions.     

利用路由器自适应限流防御分布拒绝服务攻击

提出一种自适应路由器限流算法防御分布拒绝服务攻击的机制.该算法的关键是由被攻击者要求经挑选的相距k跳(hop)的上游路由器对目的为被攻击者的数据流进行限流,从而将被攻击者的服务支援在各数据流之间达到一种类最大-最小公平的流量分配.还在一个实际的因特网拓扑上针对攻击数据流和合法数据流的不同分布和流量模型考察了算法的效果.结果表明这种以服务器为中心的路由器限流是对抗分布拒绝服务攻击的一种很有前途的方法.     

Heterogeneous CPU Services Using Differentiated Admission Control

We present an adaptive rate-controlled scheduler for heterogeneous applications running on general purpose computers. Our scheduler can effectively support diverse application requirements. It employs uniform rate-based sharing. Application heterogeneity is satisfied by partitioning CPU capacity into service classes, each with a different criterion for admission control. As a result, we are able to provide at once guaranteed performance, flexible allocation of rates with excellent scalability and intermediate service classes offering tradeoffs between reserved rate utilization and the strength of guarantees. Our scheduler has been implemented in Solaris 2.5.1. It runs existing applications without modifications. We present experimental results showing the scalability, efficiency, guaranteed performance, and overload performance aspects of our scheduler. We demonstrate the importance of priority inheritance implemented in our scheduler for stable system performance.     

On finding that speech is special.

Determined how speech is able to communicate phonological segments by sounds. Is was found that specialized processes of phonetic perception had been made to conform to the acoustic consequences of the way articulatory movements are regulated. The distinctively linguistic function of these specializations is to provide for efficient perception of phonetic structures that can also be efficiently produced. To assume that a phonetic specialization exists accords well with a "vertical" view of language (rather than the "horizontal" view expected), in which the underlying activities are seen as coherent and distinctive. Recent evidence for such special processes comes from experiments designed to investigate the integration of cues (e.g., B. H. Repp et al; see record 1980-22645-001). (60 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Long and Short of It.

Briefly discusses the length of comments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A simple theory to predict the threshold voltage of short-channel IGFET's

A simple expression for the threshold voltage of an IGFET is derived from a charge conservation principle which geometrically takes into account two-dimensional edge effects. The expression is derived for zero drain voltage and is valid for short and long-channel lengths. The dependence of the threshold voltage on the source and drain diffusion depth, r_j, and channel length, L, is explicitly given. In the limit, L/r_j → ∞, the threshold voltage equation reduces to the familiar expression for the long-channel case.The theory is compared with the measured threshold voltages on IGFET's fabricated with 1·4, 3·8 and 7·4 μm channel lengths. The dependence of the threshold voltage under backgate bias voltages ranging from zero to breakdown agrees closely with the theory.