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151.
Blends of polycarbonate and the copolyester based on 1,4-cyclohexanedimethanol and a mixture of terephthalic and isophthalic acids are known to be completely miscible. This study was concerned with various chemical events which may occur in this system, particularly during melt processing. Degradation reactions were studied by both TGA and dilute viscometry techniques, and some indications of component interaction were noted. The residual titanium catalyst from the copolyester formation was found to produce color formation by interaction with phenolic end groups in the polycarbonate and to promote interchange reactions. Both events could be suppressed by deactivation of the residual catalyst with appropriate additives. An indication of the extent of interchange reactions was obtained by following the crystallizability of the copolyester component using differential scanning calorimetry. 相似文献
152.
Preparation of Silicon Carbide/Aluminum Nitride Ceramics Using Organometallic Precursors 总被引:1,自引:0,他引:1
Corinna L. Czekaj Michael L. J. Hackney William J. Hurley Jr. Leonard V. Interrante Gary A. Sigel Paul J. Schields Glen A. Slack 《Journal of the American Ceramic Society》1990,73(2):352-357
Solid solutions of 2H -SiC/AlN can be prepared at temperatures less than 1600°C by rapid pyrolysis ("hot drop") of mixtures of [(Me3 Si)0.80 ((CH2 =CH)MeSi)1.0 (MeHSi)0.35 ] n (VPS) or [MeHSiCH2 ] n (MPCS) with [R2 AlNH2 ]3 , where R=Et, i -Bu or simply by slow pyrolysis of the precursor mixture in the case of [Et2 AlNH2 ]3 . In contrast, slow pyrolysis of mixtures of VPS or MPCS with [ i -Bu2 AlNH2 ]3 yields a composite of 2 H -AlN and 3 C -SiC at 1600°C, which transforms into a single 2 H -SiC/AlN solid solution on heating to 2000°C. The influences of the nature of the precursor and processing conditions on the structure, composition, and purity of the SiC/AlN materials are discussed. 相似文献
153.
Mary E. Mossey Yubin Xi Shayne K. McConomy Johnell O. Brooks Patrick J. Rosopa Paul J. Venhovens 《Applied ergonomics》2014
While much research exists on occupant packaging both proprietary and in the literature, more detailed research regarding user preferences for subjective ratings of steering wheel designs is sparse in published literature. This study aimed to explore the driver interactions with production steering wheels in four vehicles by using anthropometric data, driver hand placement, and driver grip design preferences for Generation-Y and Baby Boomers. In this study, participants selected their preferred grip diameter, responded to a series of questions about the steering wheel grip as they sat in four vehicles, and rank ordered their preferred grip design. Thirty-two male participants (16 Baby Boomers between ages 47 and 65 and 16 Generation-Y between ages 18 and 29) participated in the study. Drivers demonstrated different gripping behavior between vehicles and between groups. Recommendations for future work in steering wheel grip design and naturalistic driver hand positioning are discussed. 相似文献
154.
Paul R. Schwaegerle 《乙烯基与添加剂工艺杂志》1983,5(3):86-90
The flow characteristics of PVC resin are often judged by measuring the time required for a given amount of dry resin to flow through a standard funnel. However, considerable variation in test results have been found between laboratories though the test is conducted well within the procedural limits of ASTM 1895-69, “Apparent Density, Bulk Factor and Pourability of Plastic Materials.” An examination has been made of the effects of funnel hole size, funnel alignment, its type metal and wall surface smoothness, filling technique, static generated, and degree of vibration. It was found that six of these seven variables need critical control, while one (alignment) has no measurable effect. It is suggested that the data presented be used for the development of an improved ASTM test for measuring the flowability of PVC resins. 相似文献
155.
Design and Control of a Hyper-Redundant Manipulator for Mobile Manipulating Unmanned Aerial Vehicles
Manipulating objects using arms mounted to unmanned aerial vehicles (UAVs) is attractive because UAVs may access many locations that are otherwise inaccessible to other mobile manipulation platforms such as ground vehicles. Despite recent work, several major challenges remain to be overcome before it will be practical to manipulate objects from UAVs. Among these challenges are: (a) The constantly moving UAV platform and compliance of manipulator arms make it difficult to position the UAV and end-effector relative to an object of interest precisely enough for manipulation, and (b) The motions of the manipulator impact the stability of the host UAV, further complicating positioning. Solving these challenges will bring UAVs one step closer to being able to perform meaningful tasks such as infrastructure repair, disaster response, casualty extraction, and cargo resupply. Toward solutions to these challenges, this paper describes a hyper-redundant manipulator, manipulator control approaches and system design considerations to position the manipulator relative to objects of interest in such a way that impacts on platform stability are minimized. 相似文献
156.
In this paper, we investigated an approach for robots to learn to adapt dance actions to human’s preferences through interaction and feedback. Human’s preferences were extracted by analysing the common action patterns with positive or negative feedback from the human during robot dancing. By using a buffering technique to store the dance actions before a feedback, each individual’s preferences can be extracted even when a reward is received late. The extracted preferred dance actions from different people were then combined to generate improved dance sequences, i.e. performing more of what was preferred and less of that was not preferred. Together with Softmax action-selection method, the Sarsa reinforcement learning algorithm was used as the underlining learning algorithm and to effectively control the trade-off between exploitation of the learnt dance skills and exploration of new dance actions. The results showed that the robot learnt, using interactive reinforcement learning, the preferences of human partners, and the dance improved with the extracted preferences from more human partners. 相似文献
157.
The skin, skeleton and a fat-filled swim bladder of the orange roughy (Hoplostethus atlanticus) each contained greater than 20% lipid by wet weight which was almost entirely wax esters. These had carbon numbers of 34–40
consistent with the major fatty acid being 18∶1 and the major fatty alcohols being 16∶0, 18∶1, 20∶1 and 22∶1. In contrast,
the liver and the roe contained appreciable quantities of glycerolipids with 18∶1 and 22∶6 as the major fatty acids. 相似文献
158.
159.
In a recent communication it was shown that the pressure losses during the solid phase compaction of a polymeric powder could be predicted from a simple relationship of the form: where is a function of the geometry of the compact. This has now been explored in more detail and it has been found that for PVdC and PVC the factor K is dependent on the rate of compaction and the die surface finish but is independent of compaction pressure and die diameter. To illustrate the effect of the pressure losses on the structural uniformity of the compacts, microhardness measurements were taken at a large number of points across a section of each sample. A computer plot of hardness contours provided a picture of the homogeneity of the sample which could be related to the compaction conditions and average density of the compact. 相似文献
160.
The liver microsomal Δ9 and Δ6 desaturase activities have been studied in rats with carbon tetrachloride-induced hepatitis. Immediately after poisoning,
significant decreases were observed for both types of desaturase activity. However, recovery kinetics were slower for the
Δ6 desaturase than for the Δ9 desaturase. The activities of NADH-ferricyanide and NADH-cytochrome C reductases, proteins involved in the electron transfers
associated with microsomal desaturation, were also measured. There was a fall in both activities after poisoning, but this
decrease was less than that of the desaturase activities. 相似文献