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41.
Dieter Braun Manfred Rtzsch Peter Fiedler Günter Weber Heinz Hofmann Bernd Gutschalk 《大分子材料与工程》1991,187(1):101-121
Based on the example of PE-LD grades and on model substances obtained by preparative fractionation (fractions in the molecular weight range M?w = 1.2 ? 390·104 g/mol), comprehensive investigations regarding the problems of structure/properties have been carried out. The correlations of M?w with 15 physical and application technological perameters have been investigated taking into account the reaction mechanism during the manufacturing of PE-LD in the tubular and agitated autoclave reactor, resulting in the formation of so-called primary structure perameters M?n, M?w, molar mass distribution, short chain branching and long chain branching. For the interpretation of the results, among other factors, also the morphological conditions have been taken into consideration, which in connection with the molecular parameters reveal — for specific M?w-ranges — strong changes and saturation ranges, resp., for the physical and application technological properties. 相似文献
42.
In the present study the n -type electronic conduction in terms of the parameter p e, and the phase relations in several ThO2 -RE2O3 systems were examined. Large fluorite solid solution regions exist at elevated temperatures. It was demonstrated that RE2 O3 -doped thoria compositions feature lower parameters p e, and higher chemical stability than the conventional stabilized ZrO2 electrolytes. The results are given in terms of the characteristic parameter p e, in the temperature range from 1000° to 1600°C. The experimental investigations were made using a new thermodynamic measuring system. 相似文献
43.
Anna Fensel Ioan Toma José María García Ioannis Stavrakantonakis Dieter Fensel 《Computers in Industry》2014
Over the last few years, we have encountered an exponential growth in online communication opportunities. Organizations have more and more ways to connect and engage with their current or future customers. The existence of more opportunities in connecting to people can be both an enabler and a burden. Being present at a multitude of different channels requires the effective management of a very large number of adapted contents, formats, and interaction patterns fulfilling the communication and cooperation needs of distributed target groups. In this respect, we integrate existing fragmented communication and monitoring approaches into a full-fledged communication model as a basis for an adequate engagement approach. We describe applications of our approach in both the eTourism and manufacturing domain. In this paper, we introduce an approach that will enable communication, collaboration and value exchange of users through a multitude of online interaction possibilities based on the use of semantic technology. Finally, we also compare our approach with existing solutions with respect to the identified challenges in this subject. 相似文献
44.
Markus Steinberger Michael Kenzel Bernhard Kainz Peter Wonka Dieter Schmalstieg 《Computer Graphics Forum》2014,33(2):105-114
In this paper, we present a new approach for shape‐grammar‐based generation and rendering of huge cities in real‐time on the graphics processing unit (GPU). Traditional approaches rely on evaluating a shape grammar and storing the geometry produced as a preprocessing step. During rendering, the pregenerated data is then streamed to the GPU. By interweaving generation and rendering, we overcome the problems and limitations of streaming pregenerated data. Using our methods of visibility pruning and adaptive level of detail, we are able to dynamically generate only the geometry needed to render the current view in real‐time directly on the GPU. We also present a robust and efficient way to dynamically update a scene's derivation tree and geometry, enabling us to exploit frame‐to‐frame coherence. Our combined generation and rendering is significantly faster than all previous work. For detailed scenes, we are capable of generating geometry more rapidly than even just copying pregenerated data from main memory, enabling us to render cities with thousands of buildings at up to 100 frames per second, even with the camera moving at supersonic speed. 相似文献
45.
Attila Bereck Silke Dillbohner Burkhard Weber Dieter Riegel Jrg Mosel Johannes Michael Reper Axel Brakelmann 《Coloration Technology》1997,113(11):322-326
A simple method for the characterisation of fabric softness using a conventional tensile tester and a special measurement device has been developed. The method is demonstrated to be especially useful in detecting changes in softness of a given substrate due to different treatments. The results obtained, particularly hysteresis at 75% of the maximum extension, provide a good correlation with subjective ranking for samples that are subjectively distinguishable; they also differentiate well between samples which seem subjectively indistinguishable. Screening tests were carried out, mainly on wool fabrics, to find the effect of different treatments such as oxidative (alkaline and acidic) and reductive (Blankit IN) bleaching, dyeing with acid and a 1:2 metal complex, chrome and (mono and bi)reactive dyes, the effect of the antisetting agent Basolan AS (BASF) and of crosslinking with Irgasol HTW (CGY) on fabric softness. 相似文献
46.
47.
The dependence of the critical concentration of the ternary system polymer-polymer-solvent on the molecular weight can be expressed by the relation where cc is the critical concentration, M? the appropriate average of the molecular weight of both polymers; A and cc∞ are constants for the given system. The possibility of determining the molecular weight of one of the polymers from the value cc and the molecular weight of the known polymer with the aid of equation (1) is discussed. 相似文献
48.
A theoretical approach to the kinetics of the thermal decomposition of molten thermoplastic polyurethane elastomers, under conditions of thermoplastic processing, is described. On the basis of these considerations, the thermal decomposition in different instruments (melt index analyser and measuring extruder) can be described quantitatively and the various results can be compared. As a result, identical conditions of decomposition of the melt can be defined accurately, thus opening up the possibility of combining experimental values from different instruments. The fundamental kinetic equation obtained for the kinetics of the thermal decomposition of thermoplastic polyurethanes describes the decomposition reaction and the reverse reaction (formation reaction) – which is dependent on the system of measurement and processing – as a function of the molar mass (end‐group concentration) of the original product, determined from the velocity constants for the decomposition reaction and back reaction. The consideration of the limiting value for t → ∞ is in agreement with the equilibrium constant. Consequently, the development of physical characteristic functions of thermoplastic polyurethane elastomers – independent of the system of measurement – is possible.
49.
Production-integrated environmental protection – Utilization of residues . Chemical plants as well as coal-fired powerstations utilize chemical reactions in order to produce materials or energy. Most of these reactions additionally produce gaseous, liquid, or solid residues. It is the main objective of production-integrated environmental protection to use these residues as suitable feedstocks in order to reduce environmental pollution and lower the consumption of raw materials. Several examples from the BASF Group will show how, by crossing the borders of the respective plant, reasonable solutions for material, or at least energetic, utilization of residues can be achieved. As a result of permanent efforts in production-integrated environmental protection over many years and despite increasing outputs the emissions of the chemical industry have been continuously reduced. 相似文献
50.
Summary: This paper describes a step on the ambitious aim to “design” application properties of ldPE by first simulating the detailed molecular structure of a high‐pressure tubular reactor product. The reactor of a certain configuration produces under well‐defined operating conditions. The next step is to correlate the structure with the application properties. Finally, the sequence will be reversed in order to deduce the operating conditions, which lead to the desired product quality. Two‐dimensional distributions, in molecular weight and branching frequency, as well a two compartment models with a core and a shell stream were simulated and compared with experimental results. Therefore, CFD simulations were carried out to discretize the reaction medium. Samples were taken from both pilot and commercial plants. The TREF‐SEC analytical method was successfully applied in order to measure the microscopic structure of the material. The tremendous numerical problems were solved with the help of the software PREDICI .