Development of a database system for the calculation of indicators of environmental pressure caused by transport

The scope of this paper is to summarise a methodology developed for TRENDS (TRansport and ENvironment Database System-TRENDS). The main objective of TRENDS was the calculation of environmental pressure indicators caused by transport. The environmental pressures considered are associated with air emissions from the four main transport modes, i.e. road, rail, ships and air. In order to determine these indicators a system for calculating a range of environmental pressures due to transport was developed within a PC-based MS Access environment. Emphasis is given on the latest features incorporated in the model and their applications. One of the recently developed features of the software provides an option for simple scenario analysis including vehicle dynamics (such as turnover and evolution) for all EU15 member states. This feature is called the Transport Activity Balance module (TAB) and enables the production of collective results for all transport modes as well as a comparative assessment of air emissions produced by the various modes. Traffic activity and emission data obtained according to a basic (reference) scenario are displayed for the time period 1970-2020. In addition, a detailed assessment of the results produced by TRENDS was conducted by means of comparison with data found in the literature. Finally, vehicle emissions produced by the model for the EU15 member states were spatially disaggregated for the base year, 1995 and GIS maps were generated. Examples of these maps are displayed in this document, for the various modes of transport considered in the study.     

ZF6速自动变速器的技术改进-高燃油经济性和快速动态换档

在2001年,ZF率先将6速自动变速器成功推向市场。同时,5速自动变速器已经开始被新一代6速自动变速器所取代[1,2,3,4,5]。从2001年到2003年期间,3款不同转矩的变速器开始批量生产;这些变速器可适应750Nm转矩的发动机,用于标准传动、带分动器的全轮驱动以及带一体化全轮驱动装置的前置纵向传动。到2005年末,ZF公司6速自动变速器的生产份额占总产量的90%以上。自动变速器需求不断上升导致这些变速器在技术方面的改进,明显增强了决定性的、与使用者相关的参数。其中包括:.提高功率质量比;.进一步降低油耗;.改善换档动态特性。     

Traction Characteristics of Siloxanes with Aryl and Cyclohexyl Branches

The molecular structures, rheological properties, and friction coefficients of several new siloxane-based polymers were studied to explore their traction characteristics. The molecular structures including branch content were established by nuclear magnetic resonance spectroscopy, while the molecular mass distributions were determined by gel permeation chromatography. Density, viscosity, elastohydrodynamic film formation, and friction were investigated over a temperature range of 303–398 K. Film thickness and friction measurements were studied under the conditions that are representative of boundary, mixed, and full-film lubrication regimes, aiming at maximizing traction performance and temperature stability by simultaneous optimization of the size and content of ring-shaped branch structures. This study provides quantitative insight into the effect of siloxane molecular structure on the tribological performance for traction drive applications such as continuously variable transmissions.     

Investigation of the interfacial reaction between multi-walled carbon nanotubes and aluminum

Aluminum (Al)/carbon nanotube (CNT) composite films were fabricated by sputtering pure Al on the surface of aligned multi-walled CNT arrays. Heat treatment was performed in the temperature range 400–950 °C. The interfacial reaction between the Al and the CNTs was investigated by annealing the samples at various temperatures. The results indicated that aluminum carbide (Al₄C₃) was formed at the interface between the Al and CNT layers, and microscopy observation revealed that the reaction generally occurred at locations containing an amorphous carbon coating, at defect sites, and at open ends of CNTs. Because the nanosized CNTs are precursors for carbide formation, the Al₄C₃ formed is also nanoscale in size. The carbide formed on the surface as well as on the tips of the CNTs improves the interfacial interaction between the CNTs and the Al layers. This also contributes to the enhancement of the mechanical properties of the composite. Our investigation demonstrated that chemical vapor deposited CNTs are a suitable candidate as reinforcing material for Al and other metal matrices.     

Predicting and tuning physicochemical properties in lead optimization: amine basicities

This review describes simple and useful concepts for predicting and tuning the pK(a) values of basic amine centers, a crucial step in the optimization of physical and ADME properties of many lead structures in drug-discovery research. The article starts with a case study of tricyclic thrombin inhibitors featuring a tertiary amine center with pK(a) values that can be tuned over a wide range, from the usual value of around 10 to below 2 by (remote) neighboring functionalities commonly encountered in medicinal chemistry. Next, the changes in pK(a) of acyclic and cyclic amines upon substitution by fluorine, oxygen, nitrogen, and sulfur functionalities, as well as carbonyl and carboxyl derivatives are systematically analyzed, leading to the derivation of simple rules for pK(a) prediction. Electronic and stereoelectronic effects in cyclic amines are discussed, and the emerging computational methods for pK(a) predictions are briefly surveyed. The rules for tuning amine basicities should not only be of interest in drug-discovery research, but also to the development of new crop-protection agents, new amine ligands for organometallic complexes, and in particular, to the growing field of amine-based organocatalysis.     

Material adapted tool design in cold forging exemplified by powder metallurgical tool steels and industrial ceramics

The advantages of today’s cold forging technology, such as excellent mechanical properties of the workpiece and minimum waste of material together with energy saving via near net shaping increase its competitiveness against other production methods. However, as a result of extremely high loading of the tools when compared with warm and hot forging, tool life is distinctly more confined resulting in increased production costs. Due to separately or concurrently emerging damaging mechanisms of fatigue and wear at different sections of a cold forging die, process specific tool material selection and design of cold forging dies play a decisive role in near-net-shape forging of various parts. Two case studies utilizing powder metallurgical tool steel and ceramic as tool materials are presented in this paper. Successful adaptation of these materials with the help of FE simulations led to increased tool life and workpiece quality.     

Impact of processing history on rheological properties for branched polypropylene

The impact of applied processing history and the post-processing annealing procedure on the rheological properties of long-chain branched polypropylene (B-PP) have been studied intensively as compared with conventional linear polypropylene (L-PP) and low-density polyethylene (LDPE) produced by autoclave process. It was found that drawdown force, as a measure of melt elasticity for B-PP, is greatly depressed even by the short-time processing in an internal batch mixer, whereas the rheological properties of L-PP are unchanged by the processing history. Considering that the drawdown force is recovered to the original value during the post-processing annealing, the phenomenon is ascribed to the conformation change related to the branch structure, i.e. the alignment of long branches to a backbone chain, which is known as ‘shear modification’. Further, it is demonstrated that the depression of the drawdown force for B-PP is more significant than that for LDPE. Moreover, it is also clarified that B-PP needs a longer post-processing annealing time to recover the drawdown force than LDPE. The difference in the recovery curves during the annealing suggests that B-PP has less relatively ‘short’ long branches.     

Morphology and barrier mechanism of biaxially oriented poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends

To improve the barrier properties of poly(ethylene terephthalate) (PET), PET/poly(ethylene 2,6‐naphthalate) (PEN) blends with different concentrations of PEN were prepared and were then processed into biaxially oriented PET/PEN films. The air permeability of bioriented films of pure PET, pure PEN, and PET/PEN blends were tested by the differential pressure method. The morphology of the blends was studied by scanning electron microscopy (SEM) observation of the impact fracture surfaces of extruded PET/PEN samples, and the morphology of the films was also investigated by SEM. The results of the study indicated that PEN could effectively improve the barrier properties of PET, and the barrier properties of the PET/PEN blends improved with increasing PEN concentration. When the PEN concentration was equal to or less than 30%, as in this study, the PET/PEN blends were phase‐separated; that is, PET formed the continuous phase, whereas PEN formed a dispersed phase of particles, and the interface was firmly integrated because of transesterification. After the PET/PEN blends were bioriented, the PET matrix contained a PEN microstructure consisting of parallel and extended, separate layers. This multilayer microstructure was characterized by microcontinuity, which resulted in improved barrier properties because air permeation was delayed as the air had to detour around the PEN layer structure. At a constant PEN concentration, the more extended the PEN layers were, the better the barrier properties were of the PET/PEN blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1309–1316, 2006     

Zur härtung von diandiglycidylether mit anhydridmodifizierten phenolischen härtern und zu vergleichbaren in situ-reaktionen

The curing of diglycidyl ether of bisphenol A (DGEBA) with 2,6-dimethylol-p-cresol modified by hexahydrophthalic acid anhydride was investigated and compared with the analogous in situ curing of DGEBA, hexahydrophthalic acid anhydride and 2,6-dimethylol-p-cresol. The chemical reactions were investigated by means of titration and different spectroscopic and chromatographic methods. It was examined whether the less complicated and therefore cheaper in situ reaction delivers postcured products with equal or better properties. Furthermore, it was investigated whether the results are similar using technical phenolic hardeners.