The effect of infant mortality of spares on switching systemmaintenance and downtime

An exact long-term solution and a numerical approximation are presented for the impact of infant mortality of spares on switching system maintenance and downtime. The numerical approximation is used to calculate the initial transient characteristics of the number of replacements, because theoretical results are difficult to get. Results show that the impact of the higher mortality replacement rate of spares on maintenance and downtime can be significant, depending on the steady-state replacement rate of circuit packs within the system. For a hypothetical switching system, it is shown that the effect on maintenance can range from a 0.1 to 30% increase, while the effect on downtime can range from a 0.2 to 70% increase. The authors also propose a preliminary requirement for no more than a 10% increase in maintenance and downtime     

Biologic and serologic characterization of the 161A strain of Naegleria fowleri

The 161A strain of Naegleria isolated from the nasal swab of a boy (9) was grown axenically in Nelson's medium. When 10,000 amoebae from the axenic medium were inoculated onto each monkey kidney cell (Vero) culture, characteristic cytopathic effects (CPE) were noticed in 4 to 5 days. The CPE consisted of granulation of the host cell cytoplasm, cell shrinkage, nuclear pycnosis, and discontinuity of cell sheet. When 10,000 amoebae were instilled intranasally into a group of ten 2- to 3-week-old mice, 8 of the 10 mice exhibited characteristic symptoms of primary amoebic meningoencephalitis and died within 10 to 12 days. Histopathology of the brain revealed necrotic tissue and an acute inflammatory reaction in the superficial regions of the brain. In the gel diffusion and immunoelectrophoresis tests the sonically disrupted antigens of 161A amoebae reacted extensively with the hyper-immune sera against 3 strains (CA, CJ, HB-1) of pathogenic N. fowleri and produced patterns very similar to those produced by the homologous systems. Further, anti-HB-1 serum absorbed with the 161A antigens failed to react with the antigens of HB-1, CA, CJ, and 161A strains thus indicating antigenic identity of 161A strain with N. fowleri. In view of these observations it was concluded that the strain 161A is pathogenic and should be reclassified as N. fowleri.     

The removal of acid dye from effluent using natural adsorbents—II Wood

The ability of wood to adsorb Telon Blue (Acid Blue 25) has been investigated. The effects of contact time, particle size and adsorption capacity have been studied. In addition a series of fixed bed experiments were performed to study the flow system in an attempt to simulate industrial conditions on a small scale.     

Forms of probability-density functions obtainable from summed m sequences

The letter discusses the sums of m sequences generated by a feedback shift register where the summed sequences are not necessarily from successive stages. A method for obtaining all the possible probability-density functions is given. The particular case of five stages is studied in detail. It is found that, for this case and a number of other cases tested, the rth moment (or central moment) is identical for all the situations in which there are at least r interdependent stages in the sum.     

合成纤维和玻璃纤维制成的Ashrae过滤介质的性能比较

对常用的超细玻璃纤维制成的Ashrae袋式过滤介质、标准驻极熔喷聚丙烯Ashrae袋式过滤介质和一种新型的熔喷聚丙烯细纤维Ashrae袋式过滤介质进行了比较。标准玻璃纤维毡所用的纤维非常微细,密实性(固体体积分数)很低,导致α值(品质因子)较高,但该材料不能吸附静电荷。标准熔喷聚丙烯过滤介质所用的纤维比玻璃纤维粗得多,密实性也更高,因能吸附很多静电荷,其初始α值比玻璃纤维毡要大得多,但放电后的α值却比玻璃纤维毡低得多。新型的熔喷聚丙烯细纤维过滤介质可完全驻极,其初始α值和标准熔喷聚丙烯过滤介质一样高,但由于更加细微的纤维结构,在放电后所保持的α值更高。