Stability of Rotors Under the Combined Influence of Fluid Film Bearing Characteristics and Shaft Material Damping

Fluid film characteristics and shaft material damping form an interesting combination in rotor dynamic applications. Under certain conditions, a rotor which is unstable due to the damping, can be stabilized with the proper choice of fluid film bearings as supports. On the other hand, increasing the material damping in the rotor shaft can attenuate stress fluctuations in the rotors supported by fluid film bearings. The influence of the above combination on the stability of rotor bearing systems is investigated using a Jeff cot rotor with significant material damping and supported by fluid film bearings in the rotor dynamic model. The results indicate that under certain conditions, the interaction of the above two factors can be gainfully utilized in the design of rotor bearing systems.     

Impact of Process Conditions on Digestibility of Pea Starch

This study investigated how process conditions affect the digestibility of pea starch from pea starch powder (PSP). The factors considered were resistant starch (RS), slow digestible starch (SDS) and rapidly digestible starch (RDS) content. The examined five process factors were: material/water ratio, cooking temperature, cooking time, soaking time, and heat dehydration time. Changes in process conditions mainly altered the content of RS and SDS. Analysis with Sephadex G-200 chromatography and differential scanning calorimetry revealed that RS was mainly from retrograded amylose and amylopectin, while SDS and RDS were mainly derived from amylopectin.     

Quantification of Resistant Starch in Several Starch Sources Treated Thermally

The purpose of the research was to determine the effect of heat-moisture treatment at different phases and temperatures on resistance starch (RS) level on native starches samples of several botanical sources and to evaluate the thermal stability of different granules. Samples of potato, cassava, wheat, and corn starches were moisturized up to 30% wet basis and then treated in a convection oven at 80, 100, and 120°C during 40 and 60 minutes. RS was determined gravimetrically by a modification of Method 991.43 of the AOAC for the determination of total dietary fibre. All samples were submitted to different thermal analysis in a range from 40 to 180°C at 10°C/min. Overall, in the treated samples an increase of RS was observed, being the corn starch sample treated at 120°C and 60 minutes – the one that presented the highest content of RS (4.2%). Other treated samples showed a decrease in the gelatinization enthalpies with the presence of granular fusion, indicating internal re-arrangement, an increase in the gelatinization temperature and the thermo stability below 95°C.     

Performance of three different types of resistant starch in fried battered food

Three different types of commercially available RS (one RS type 2 and two RS type 3) were incorporated in a batter formula and their influence on the rheological properties of the raw batter and on the batter pick-up, texture, colour, and consumer acceptability of the final battered fried product were investigated. RS incorporation affected the rheological properties of the raw batter compared with a control (without RS), although no relation between RS type and the flow and viscoelastic properties was found. In comparison to the control batter, replacement of wheat flour with Novelose 330 (RS3 type) increased significantly batter consistency and the values of the viscoelastic moduli G′ and G″, while replacement with both C*Actistar 11700 (RS3 type) or Hi-maize 260 (RS2 type) produced the opposite effect. Instrumental colour was the only property that gave a clear relationship with the type of RS; the two RS3 starches developed a darker colour than the control and the RS2 starch. The RS2 starch showed the best acceptability evaluated by a consumer panel. All the RS types assayed are considered successful to be used in battered food.     

Fermentation of resistant food starches by human and rat intestinal bacteria

Resistant starches prepared from maize and peas were fermented in vitro with rat or human intestinal bacteria. With both inoculum types, degradation of pea starch after 24 h incubation (0 and 47% utilised by rat and human organisms, respectively) was markedly slower than that of maize starch (73 and 85%) and was incomplete even after 7 days' incubation; degradation of both starches was slower than with soluble starch or sucrose. The slow degradation of pea starch was not due to the presence of intact cell walls. Qualitatively, the production of C2-C4 volatile fatty acids was similar for all substrates and both inoculum types but there were some quantitative differences. If resistant food starches are to be regarded as dietary fibre, then, like ‘true’ fibre, any physiological effect in vivo may depend on the type of starch involved.     

电子电气用有机硅胶粘剂

介绍了电子电气用有机硅胶粘剂的基本性能和种类，以及高透明性、导电性、散热性、快干非腐蚀性和芯片焊接用、耐热粘接密封用等有机硅胶粘剂。     

1.25Cr0.5Mo钢在加氢反应器上的应用

分析了 1 2 5Cr0 .5Mo钢在凡士林加氢反应器上的应用情况 ,指出 1 2 5Cr0 .5Mo钢在不十分苛刻的环境中使用是完全可行的     

Schweißzusatzwerkstoffe können/müssen nicht immer die Anforderungen der Grundwerkstoffe erfüllen

Weld metal as strong as base metal? The development of new steels is always a challenge for the manufacturer of filler metals. In many cases it is obvious that some properties of the base metal cannot be fulfilled with matching filler metals. In some cases, dissimilar filler metals can solve the problem in some cases, there is no chance to meet the requirements of the base metal (for example yield strengths of new ultra high strength steels). This paper deals with different kinds of new steels and the requirements for the weld metal with examples from motor car industry (Mangan Austenite), crane (Ultra high strength steels), earthmoving machinery (Wear‐resistant steels) and offshore (Supermartensitic steels). Specific problems will be discussed and best solutions will be highlighted. These examples make clear that the success of new kinds of steels in the market depends on solving the joining problems of these steels.     

打火机CR装置创新设计方法研究

研究打火机CR安全装置创新设计方法，描述创新设计思路及其在设计过程中的应用，指导打火机CR装置设计。     

地聚合物新型固井胶凝材料及其抗盐性能分析

针对深井高盐环境中水泥浆固井胶凝材料耐腐蚀性低的问题,提出了地聚合物作为一种潜在新型固井胶凝材料的可行性,并对其抗盐性进行了实验分析。通过测量粉煤灰+偏高岭土基地聚物和G级油井水泥在不同浓度盐溶液中养护28 d的抗压强度,发现水泥试件随着盐溶液浓度提高,强度损失增大,而地聚物试件的强度却随着盐浓度的提高逆势提升。通过XRF元素分析、XRD矿物分析、酸碱性分析发现,盐水环境中的离子交换显著改变了水泥的水化环境和生成物成分,导致其强度显著降低,但对地聚物的地质聚合反应产物影响甚微。扫描电子显微镜SEM下的形貌分析表明,盐水环境可使地聚物产生更加致密的微观结构,这是其强度提高的主要原因。该研究表明,早龄期地聚物具有优异的抗盐性能,可在进一步加强实验验证后考虑在深井高盐腐蚀环境中代替水泥使用。