以创新引领主轴技术

本文论述了电主轴设计的生产战略与重要性：高动态特性和高刚度机床有助于保证大功率切削(HPC)和高速切削(HSC)加工生产战略。因此．电主轴结构必须满足下述要求：在HPC生产中要有最大功率和力矩，在HSC生产中要减轻重量和有振动阻尼，以达到最高速度。论述了电主轴设计的当前工艺水平及前景，简要介绍电主轴部件及相关技术：电机、轴承技术、刀具夹紧系统、冷却和润滑系统、传感系统及数据采集与分析的集成电子装置，显示了未来主轴的潜力。其焦点问题是“主轴”与其“外围”设备系统之间的相互作用，如冷却致冷系统，热膨胀控制与补偿系统，电气、电子元件与物理测量系统。介绍了最新技术革新：Hydro-F的主题是带集成转子冷却与液压刀具夹紧系统的液体静压轴承主轴。生产实验将说明液体静压主轴有着优良的性能、速度和过程稳定性并确定其应用范围。Smart Vision是电主轴的数据采集、评价与监控电子系统。关键参数，如轴承温度、换刀次数、电机功率与转矩的监控是保证其过程稳定性和预测其使用寿命的基础。未来系统将可以与操作者主动通讯或采用某种接口，减少意外停机。将就实时解决方案做一介绍。     

The hierarchical SMAA-PROMETHEE method applied to assess the sustainability of European cities

Measuring the level of sustainability taking into account many contributing aspects is a challenge. In this paper, we apply a multiple criteria decision aiding framework, namely, the hierarchical-SMAA-PROMETHEE method, to assess the environmental, social, and economic sustainability of 20 European cities in the period going from 2012 to 2015. The application of the method is innovative for the following reasons: (i) it permits to study the sustainability of the mentioned cities not only comprehensively but also considering separately particular macro-criteria, providing in this way more specific information on their weak and strong points; (ii) the use of PROMETHEE and, in particular, of PROMETHEE II, avoids the compensation between different and heterogeneous criteria, that is arbitrarily assumed in value function aggregation models; finally, (iii) thanks to the application of the Stochastic Multicriteria Acceptability Analysis, the method provides more robust recommendations than a method based on a single instance of the considered preference model compatible with few preference information items provided by the Decision Maker.

     

Mechanochemical activation as a tool of increasing catalytic activity

The role of structure–energy properties of mechanically induced defects in the crystal structure of heterogeneous catalysts is considered. The main concepts of the mechanochemical activation effect on the activity and selectivity of catalysts are discussed. The wasteless and energy-saving methods of preparation of some catalysts are presented. Rigorous experimental proofs of the influence of defects in the crystal structure of catalysts on their specific catalytic activity are obtained. High performance of mechanochemical catalysis application for hydrogenation, oxidation, amination and hydroalumination processes is shown. For the first time catalytic reactions under the conditions of mechanochemical activation at elevated temperature and increased pressure of gases are carried out.     

Fabrication of Ti-Al composite coatings by the mechanical alloying method

The method of mechanical alloying (MA) allows one to fabricate sufficiently thick and dense composite coatings using short-time treatments at room temperature. The method is very simple and requires no special atmosphere. It was used to synthesize coatings of Ti-Al, Ti-Al-W-C, and Ti-Al-Si on the titanium surface. During the heating of Ti-Al composite coatings in a temperature range of 600–1000°C, Ti-Al intermetallic phases are formed on the titanium surface. In Ti-Al-Si coatings annealed at 900–1000°C, Ti-Al intermetallic and silicide phases are the basis of the coatings. The temperature ranges of phase and structural transformations in the coatings depend on the initial chemical composition. For the thermal stabilization of Ti-Al intermetallic phases, additions of alloying elements retarding diffusion in the Ti-Al system can be used.     

Dynamische Untersuchungen von Eisenbahnbrücken

Dynamic Investigations of Railway Bridges Over the last decades, the cruising speed of railway traffic has increased considerably within Europe. Apart from the technological developments achieved in the field of high‐speed trains, several measures were required on the railway track. A location with large curve radius and proper superelevation is required in addition to a sufficient long‐ and short term stability of the superstructure also in view of high dynamic loads. Whereas these requirements usually are met on the free track, on railway bridges resonance effects may cause serious problems in terms of dynamic response. Triggered by these aspects, a specific chapter in Eurocode 1 is dedicated to dynamic calculations of railway bridges. In the presented paper current knowledge derived from dynamic investigations of bridges is summarised.     

Utilisation of nitrates - a decisive criterion in the selection ofLactobacilli for bioconservation of vegetables

This work presents results of the observations of cabbage and carrot juice fermentation after inoculation with pure cultures of lactic acid bacteria. From the point of view of nitrates, utilisation, the most suitable microorganisms found from those studied wereLactobacillus plantarum 92H,Lb. plantarum 90H andLb. delbrueckii 37H. At the same time, other observed parameters were assessed as well for their suitability for vegetable bioconservation.