Kurvengetriebe mit umlaufender Doppelkurve zur erzeugung von Bahnkurven mit vorgeschriebener geschwindigkeit

Methods of producing plane curves by linkages have often been described; many papers deal with these. It is surprising that the use of cam-linkages for this purpose is rarely treated. If it is required that a coupler point follow a given closed curve and, in addition, that its velocity at each position be prescribed, two closed cam profiles are necessary. Several papers in the past have shown how to produce a desired curve, but in most the velocities have been neglected. A systematic approach is here used to indicate the structures of all suitable cam-linkages having two closed cams. In this paper only those designs are investigated which have a fully rotating input cam body consisting of two profiles. In order to find the least expensive mechanisms, only four link cam-linkages are considered.In the opinion of the author, here is one of the most important and most serious problems of designers, i.e. the need to solve each problem in the best way and also with a minimum of expense. There are many difficulties in doing this. In the problem discussed here, four free parameters have to be assumed at random or by experience with the problem itself. This means that there are ∞⁴ possible assumptions of initial dimensions. How can the best be found? After having chosen them, the best main dimensions of the cams can be determined exactly when the admissable transmission angle is prescribed. This is the major significance of the paper! As former papers of the author have shown, the transmission angle is determined by the position of the instant centers, which relate to the first derivatives of motion, i.e. the velocity ratio of a function or the tangent of a curve.After a simple example (producing a straight line), a more complicated problem is solved. In a machine, a workpiece is to be transported between three dwell stations in the best way. It is described as follows: The dwells have to be realized exactly, that is, without approximation; (this can easily be fulfilled by having circular arcs on the cams). Then the motion between the dwell stations has to be optimized to give the smallest possible accelerations. As a straight line is still the shortest connection of two points, an equilateral triangle is prescribed as the curve to be produced. In its corners the dwells take place. Between the dwells the cycloidal function is used as one of the best laws of motion.     

Die Elasto-Statik-Element-Methode zur Ermittlung der elastischen Verhaltensweise von Vierwalzengerüsten und ihre Anwendung bei der Bandwalzung

Zusammenhang zwischen dem Bandprofil und der Planheit. Betrachtung der Walzen als belastete Balken auf und in elastischen Bettungen. Lösung von zwei inhomogenen linearen Differentialgleichungen. Ableitung der Bettungsziffern aus den partiellen elastischen Formänderungen der Walzenballen und der Bandumformung. Ermittlung der Konstanten aus einer Matrix für die Rand- und Stetigkeitsbedingungen. Darstellung der Arbeitswalzenschliffe, der Durchbiegungen der Stütz- und Arbeitswalzen und der Pressungsverteilungen. Modellanpassung für Stütz- und Arbeitswalzenzusatzbiegesysteme.     

Influence of volume fraction and dispersion rate of grain-boundary cementite on the cold-rolling textures of low-carbon steel

On the technical background of elevated coiling temperatures the influence of the precipitated volume fraction and of the dispersion rate of grain boundary cementite on cold-rolling textures in low carbon steel was investigated. Whilst different dispersion rates with constant cementite volume do not reveal any distinct influence, the rolling texture is lowered by increasing the precipitated volume fraction of cementite.     

Characterization of and male adaptation to pheromone of femaleTrichostrongylus colubriformis (Nematoda)

Males of the ruminant nematodeTrichostrongylus colubriformis were significantly attracted to an incubate from their females during in vitro assay. Exposure of males to sera from uninfected and infected animals or selected neurotransmitters had no effect on their subsequent responsiveness to the female's pheromone. In contrast, exposure to 1500 female-hours of pheromone decreased male responsiveness after moderate rinsing prior to bioassay. Rinsing of the males with larger volumes of Tyrode's solution prior to in vitro assay increased their subsequent response to the female's pheromone. High-performance liquid chromatography yielded a presumptive pheromone peak with a fivefold increase in biological activity. This peak was soluble in alcohols and tetrahydrofuran, based on elution from reverse-phase Sep-Pak cartridges. Stability of the peak was increased by EDTA or ascorbic acid (10 mM). Storage for six weeks in ascorbic acid at 4 °C allowed recovery of 47.3% of the original material.Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

A comparison of the carbon-13 n.m.r. spectra of solid coals and their liquids obtained by catalytic hydrogenation

High-volatile bituminous and lignite coals have been studied by means of carbon-13 n.m.r. employing cross-polarization and magic-angle-spinning techniques. The solids spectra have been compared to those of the coal-derived liquids. By artificially broadening the high-resolution spectra of the liquids, a striking similarity in line shape and position is observed when the liquid spectra are compared with those of the corresponding solid coal. It is noted however that certain bands visible in the solid are no longer present in the liquefied state. The significance of these results is discussed in terms of carbon skeletal structures present in the solids but not in the liquids.