高强度高压绝缘子产品质量同其结构性能的重要关系(续)——制造者和用户应共同掌握的规则和指标(第二部分)

6　各种电瓷结构分析实例证实结构的差别下面介绍各种电瓷结构分析的结果。从扫描电镜照片 (ＲＥＭ)的判读中可见到这些材料的差别。试样ａ:日本瓷绝缘子Ｃ1 1 0 /1 1 2 ,制造年代 1 997试样ｂ :西门子瓷绝缘子Ｃ1 2 0 ,Ｃ1 3 0 ,制造年代 2 0 0 1试样ｃ:高强度矾土瓷绝缘子 ,西门子 2 0 0 1开发陶瓷岩相试样的制备系经多级金刚石研磨和抛光以及化学浸蚀。为判定气孔状态 ,对磨片作了透光照片 ,在其光亮区放大倍数为 1 0 0∶1 ,而且扫描电镜照片放大倍数为2 0 0∶1。图 5ａ　试样ａ光片的ＬＭ(透光显微镜 )和ＲＥＭ(扫描电镜 )图象 ,放大倍…     

矾土瓷—一种新型高电压强度的绝缘材料

使用经筛选的专用粘土原料和不同种类、不同用量的熔剂，并使用作为新型氧化铝基质的矾土，就可开发出一种高Al2O3的新型优质瓷。这种瓷具有良好的强度，特别是它的长期性能，还降低了制造成本。因此，新型矾土瓷的发展前景广阔。     

Effects of visual guidance on the reduction of impacts during landings.

While a common view is that vision is essential to motor performance, some recent studies have shown that continuous visual guidance may not always be required within certain time constraints. This study investigated a landing-related task (self-released falls) to assess the extent to which visual information enhances the ability to reduce the impacts at touchdown. Six individuals performed six blocked trials from four height categories in semi-counterbalanced order (5-10, 20-25, 60-65, and 90-95 cm) in vision and no-vision conditions randomly assigned. A series of two-way ANOVA with repeated measures were carried out separately on each dependent variable collapsed over six trials. The results indicated that vision during the flight did not produce softer landings. Indeed, in analysing the first peak (PFP) a main effect for visual condition was revealed in that the mean amplitude was slightly higher when vision was available (F(1,5) = 6.57; p less than 0.05), thus implicating higher forces at impact. The results obtained when the time to the first peak (TFP) was applied showed no significant differences between conditions (F(1,5) less than 1). As expected, in all cases, the analyses yielded significant main effects for the height categories factor. It appears that during self-initiated falls in which the environmental cues are known before the event, visual guidance is not necessary in order to adopt a softer landing strategy.     

Manufacture of amorphous alloy ribbons

Amorphous alloys are prepared in continuous ribbon form by rapid quenching directly from the melt. In particular, the process of chill block melt-spinning involves the continuous impingement of molten alloy against a rapidly moving substrate surface. Principles of chill block melt-spinning are presented with regard to the formation of continuous, rapidly-quenched amorphous alloy ribbon. The effects of numerous process variables on sample geometry and physical properties are examined through experimental results obtained by the author and by other researchers. Principles of narrow ribbon manufacture are extended to describe means of fabricating wide ribbon. Manufacturing problems unique to extended runs and potential solutions are cited. Effects of process parameters on magnetic and physical properties of as-cast samples are discussed.     

Configuration interaction calculations of positron binding to molecular oxides and hydrides and its effect on spectroscopic constants

Ab initio multireference single- and double-excitation configuration interaction (MRD-CI) calculations have been carried out for magnesium oxide (MgO) and lithium oxide (LiO) and their positronic complexes. These results are compared with previous theoretical data obtained earlier for beryllium oxide (BeO) and the series of alkali hydrides with and without an additional positron. Potential curves have been constructed for each of the systems, MgO, e⁺MgO, LiO and e⁺LiO. Positron affinities (PAs) of 0.472 eV and 0.304 eV, respectively, have been computed for the ground states of MgO and LiO. Because of the relatively low ionization potential of the Li atom, it is found that the dissociation limit in the latter case is Li⁺ + PsO (Oe⁺e⁻), whereas it is Mg + e⁺O in the former case, in close analogy to what has been found for e⁺BeO. Significant changes in bond lengths, vibrational frequencies and dissociation energies are indicated as a result of binding a positron to each of these oxides as well as to the alkali hydrides studied earlier. The general trend observed is toward increased bond length and decreased frequency as a result of attaching a positron to these systems in their various low-lying electronic states.     

Piloting of anionic polymerization of styrene in tetrahydrofurant

Anionic polymerization of styrene in THF with n‐butyllithium/alpha‐methylstyrene initiator is described as a first step in preparation of a styrenic block copoly‐mer. In order to suppress rapid decay of living alpha‐methylstyrene unimers, which occurred at room temperature, the initiation reaction was carried out at ?20(+5)°C. The kinetic parameters of this decay reaction were determined and used for process optimization. By combining experiments with modelling of styrene propagation reaction all key process parameters were defined for l‐L, 38‐L, and 189‐L reactors. A good match was demonstrated between the model and experimental propagation exotherm for semibatch reaction conditions. Overall, it was demonstrated that technical grade THF and styrene could be used at pilot plant scale to prepare well‐defined polymers up to Mn 22 000 via the “living” polymerization mechanism. The resulting polymers had narrow molecular weight distributions (1.06 < Mw/Mn < 1.30).     

Characterization of amorphous alloys by thermal analysis techniques

Various thermal analysis studies were conducted to characterize metallic glasses. The methods used, namely differential scanning calorimetry, dilatometry, dynamic mechanical analysis and thermomagnetometry, are shown to be useful for studying thermally induced phenomena. Examples covered demonstrate the usefulness of thermal techniques in evaluating structural relaxation. Curie temperature, glass transition, and devitrification processes. A basis of understanding structural relaxation and the glass transition is discussed in terms of a diagram of enthalpy against temperature.     

Apparat und Verfahren zur Bestimmung der Qualit?t des Weizenklebers

Ohne Zusammenfassung     

Ein neues Verfahren zur Bestimmung des Feinheitsgrades der Weizenmehle

Ohne ZusammenfassungMitteilung aus dem Hygienischen Institut der Universität Budapest. (Direktor: Prof. L. v. Liebermann.)