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1.
Timothy Thomasma Kurt Hilbrecht 《International Journal of Flexible Manufacturing Systems》1991,3(3-4):231-250
Good methods are needed to specify, test, and debug material-handling control logic. This article surveys a number of representative methods for defining and describing control algorithms for programmable material-handling equipment used in flexible manufacturing systems. The methods are evaluated with regard to their suitability for communication between people and as bases for interfaces to automatic program generators. It is concluded that no single method is entirely satisfactory. Three methods (position diagrams, function block diagrams, and operation networks) have potential to be combined into an effective hybrid approach that minimizes the need for the user to switch between various conceptual models. 相似文献
2.
3.
The parallel language FORK [1], based on a scalable shared memory model, is a PASCAL-like language with some additional parallel constructs. A PRAM (Parallel Random Access Machine) algorithm can be expressed on a high level of abstraction as a FORK program which is translated into efficient PRAM code guaranteeing theoretically predicted runtimes.
In this paper, we concentrate on those features of the language FORK related to parallelism, such as the group concept, a shared memory access and synchronous or asynchronous execution. We present a trace-based denotational interleaving semantics where processes describe synchronous computations. Processes are created or deleted dynamically and run asynchronously. Interleaving rules reflect the underlying CRCW (concurrent-read-concurrent-write) PRAM model. 相似文献
4.
Kurt F. J. Heinrich 《Journal of research of the National Institute of Standards and Technology》2002,107(6):483-485
Quantitative electron probe analysis is based on models based on the physics or x-ray generation, empirically adjusted to the analyses of specimens of known composition. Their accuracy can be estimated by applying them to a set of specimens of presumably well-known composition. 相似文献
5.
Summary Potential polymeric herbicides have been synthesized by reacting poly(acrylic acid)s with 3-aniino-1,2,4-triazole and 1-acetyl-5-amino-1,2,4-triazole, respectively. The produced copolymers contained the active moieties as pendant groups in the range of 3 to 27 per cent of weight and with a content of carboxyl groups up to 95 mol-%. The hydrolytic release of 3-amino-1,2,4-triazole was investigated.Part 12: M. Hartmann, H,-J. Bauer, A. Pritzsche and K. Wermann, Makromol. Chem., in press 相似文献
6.
The man-machine dialog is very important for the design process. In this paper a program system, based on the minicomputer KRS 4201 (ROBOTRON), is demonstrated by using an interactive graphical screen. This program system provides the opportunity to analyze and synthesize mechanisms up to 16 links. The application is demonstrated by designing a front-loader-system for a truck. Real-time animation of seven-bar linkages and coupler curves, including velocity and acceleration, are shown. 相似文献
7.
Kurt F. Wissbrun 《Polymer Engineering and Science》1991,31(15):1130-1136
Thermotropic polyesters, such as Vectra (Hoechst Celanese), have excellent moldability for intricate parts that require high precision of form, such as electronic connectors. Two apparently contradictory aspects of molding behavior contribute to the moldability. On the one hand, the low viscosity of the liquid crystalline polymer (LCP) at high shear rates favors ease of filling molds that contain long, thin paths. On the other, parts molded from LCP have little or no flash to interfere with the functioning of the parts. There has apparently been little work on the rheological aspects of flash formation. An approximate analysis is made by considering that the flash is the result of melt being extruded from the mold cavity into a slit at the mold parting line. The driving force for the extrusion is the injection pressure. The flow is assumed to be isothermal until solidification occurs, at a time that depends on the thickness of the slit, on the thermal diffusivity of the melt, the melt and mold temperatures, and on the solidification temperature of the material. The viscosity is assumed to have power-law dependence on shear rate. It is found that when the aspect ratio (length to thickness) of the flash is small, its length is strongly dependent on the magnitude of the pressure drop at the contraction from the cavity to the slit. At the minimum pressure required to fill a mold, the flash length is predicted to be independent of the rheological and thermal properties of the melt, except for the power-law exponent. Differences in end correction can, however, account for different tendencies to flash at equal moldability. Comparison of the model with Richardson's analysis of freezing in a cavity suggests a correlation of the thermal properties of the melt with his parameter c, which is related to mold filling ability. Tests of the model and possible refinements are suggested. 相似文献
8.
Five microalloyed ferritic steels with a Cr content of 10 to 17 % were cold rolled and recrystallized. Steels with a high volume fraction of Nb and Ti precipitations revealed a deviation from the typical {111} fibre texture. The new main component {557}<583> was explained by particle induced growth selection. 相似文献
9.
Zusammenfassung Aufgrund von Eingangs- und Ausgangsst?rungen des Me?systems sowie einer endlichen Frequenzaufl?sung treten stets systematische
(Bias-) und zuf?llige Fehler bei gemessenen Frequenzg?ngen und deren Varianzen auf. Auf solchen Frequenzg?ngen und Varianzen
beruhende Sch?tzungen der modalen Parameter sind damit ebenfalls systematisch verzerrt. Um die Genauigkeit und Sicherheit
der modalen Parameter zu erh?hen, wird ein Sch?tzverfahren vorgestellt, in dem der Einflu? der Biasfehler auf die Sch?tzung
n?herungsweise in einer diagonalen Wichtungsmatrix berücksichtigt wird. Es wird gezeigt, da? die systematischen Fehler Einflu?
auf die Absch?tzung der statistischen Sicherheit der modalen Parameter haben. Anhand zweier Beispiele wird die Wirksamkeit
des Sch?tzverfahrens demonstriert.
Prof. Dr.-Ing. Dr.-Ing. E.h.H.K. T?nshoff: Dipl.-Ing.Z. Liu, Institut für Fertigungstechnik und Spanende Werkzeugmaschinen (IFW), Universit?t Hannover. 相似文献
10.
Luk Chiu Li Jagdish Parasrampuria Ron Levans Kurt G. Van Scoik 《Drug development and industrial pharmacy》1994,20(13):2079-2090
The moisture-uptake kinetics of a hygroscopic powder, sodium heparin contained in a cylindrical container, was determined using a novel moisture-uptake measuring device under a constant convective air flow. The amount of moisture uptake increased with the increase in the relative humidity of the air. The effect of powder-bed height on the total amount of moisture uptake was found to be significant only at the highest relative humidity (75%) evaluated in this study. However, the percent of weight increase of the powder as a result of moisture uptake decreases as the height of the powder bed increases. The results of this study are explained by the dynamic nature of the moisture-uptake process associated with the instrument. 相似文献