Lubricant Replenishment in Rolling Bearing Contacts

It is generally assumed that starved lubricated contacts in rolling element bearings are replenished by side flow. The rolling elements partly push the lubricant to the side of the contacts after which the re-flow will provide fresh lubricant for the next rolling element. This re-flow is driven by surface tension and restricted by the viscosity. Hence, thick oils or greases may yield problems here, which is generally observed in practice. This paper quantifies this re-flow by means of a numerical model using a so-called thin layer/film assumptions. The results here show that this form of replenishment may happen to some extent in single contacts but for sure not in rolling element bearings. There are two reasons for this: the time between successive overrollings is too short and secondly, the centrifugal effects on the inner ring will drive the flow in a vertical direction rather than transversely. This applies to cylindrical roller bearings (CRB)-type of surfaces. This may be different for tapered or spherical bearings, which should be the topic of future research.     

Towards photostatistics from photon-number discriminating detectors

Abstract

We study the properties of a photodetector that has a numberresolving capability. In the absence of dark counts, due to its finite quantum efficiency, photodetection with such a detector can only eliminate the possibility that the incident field corresponds to a number of photons less than the detected photon number. We show that such a non-photon number-discriminating detector, however, provides a useful tool in the reconstruction of the photon number distribution of the incident field even in the presence of dark counts.     

A digital signal-processing analysis technique for the infrared reflectivity characterization of ion implanted silicon

A new method for the characterization of ion-implanted silicon is proposed. It is based on analysis of the Fourier spectrum of bilinearly transformed infrared reflectance versus wavenumber data of ion-implanted samples. This non-destructive technique has been applied to previously published infrared reflectance data of 〈111〉 and 〈100〉 oriented Si samples which had been implanted with 2.7 MeV phosphorus and 380 keV silicon ions, respectively, and annealed at 500° C for various lengths of time. The refractive index and thickness of the amorphous layer of the as-implanted samples can be measured directly by means of this technique. The position of boundaries between the amorphous, recrystallized and substrate zones, as well as the position of the carrier concentration peak can be determined for the various annealing times. Depending on the annealing time, the recrystallized layer in 〈111〉 silicon has a refractive index which is between 2% and 4% higher than the substrate refractive index, while the difference in refractive index between the amorphous and recrystallized layers is in the order of 5%. In contrast to these results, the presence of the substrate/recrystallized material interface could not be detected in partially recrystallized 〈100〉 silicon by this method, implying that the refractive index step at the substrate/recrystallized material interface is less than 1%. The step in refractive index at the crystalline/amorphous interface in 〈100〉 silicon implanted with a dose of 0.5 x 10¹⁶ cm⁻² silicon ions, was measured to be 12%, and it is reduced to 8% after partial regrowth has occurred. These results confirm the data obtained by a model-based least-squares analysis.     

Sources of error in the graphical analysis of CFD results

Graphical techniques are widely used to analyze CFD solutions. Some of these techniques have inherent errors, making them represent the solution imprecisely. An understanding of these errors is important for proper interpretation of the computed results and for comparison with experiments. Examples include contouring, plotting of vector fields, particle tracing, and computation of flow functions involving integration or differentiation.This paper is declared a work of the U. S. Government and therefore is in the public domain.     

THE REACTIONS BETWEEN POLYPHENOLS AND ALDEHYDES AND THE INFLUENCE OF ACETALDEHYDE ON HAZE FORMATION IN BEER

The reactions and interactions between proteins and polyphenols are, among other phenomena, responsible for haze formation in beer. The participation of aldehydes in the polymerisation of polyphenols is considered. The formation of phenolic Baeyer-type condensation products containing phenolic residues linked by CH₃CH-bridges through reaction with acetaldehyde is possible at the pH of beer (4.0). These and other reactions with acetaldehyde in beer participate in beer haze formation.     

Human‐knowledge resources and interorganisational systems

This paper analyses how human‐knowledge resources affect interorganisational systems (IOS) capabilities and subsequently attainment of operational and strategic benefits. A conceptual model is constructed combining the transaction cost economics (TCE) view, resource‐based view (RBV) and insights from IOS literature. The model is tested through a triangulation approach combining two qualitative case studies and a quantitative field study within the logistics sector. This sector is chosen due to its need for high reliance on information technology. The findings indicate that human knowledge positively influences IOS capabilities related to cross‐organisational business processes and transfer of knowledge. Findings also show that strategic benefits are the consequence of knowledge transfer, when the transfer supports business processes resulting in operational benefits. The main theoretical contribution of this paper is that it combines a TCE view and RBV to analyse the effect of relationship‐specificity of human‐based knowledge resources in IOS.     

Progress beyond policy making? Assessing the performance of Dutch-German cross-border cooperation in Deltarhine

ABSTRACT

This longitudinal study assesses the performance of the Dutch-German cross-border water regime using a combination of performance indicators. The regime has, despite many efforts over five decades, rarely progressed beyond policy making and hardly contributed to actual problem-solving for issues such as water pollution or river restoration. Stakeholder satisfaction is nevertheless high, showing that combined performance indicators are needed to assess cross-border cooperation, and performance cannot simply be equated with problem-solving and goal attainment. Practical policy advice is provided to progress beyond policy making, focusing on policy design, network management and the adequacy of resources (financial, human, legal) for policy implementation.     

Uniquely connecting frequency domain representations of given order polynomial Wiener–Hammerstein systems

The notion of frequency response functions has been generalized to nonlinear systems in several ways. However, a relation between different approaches has not yet been established. In this paper, frequency domain representations for nonlinear systems are uniquely connected for a class of nonlinear systems. Specifically, by means of novel analytical results, the generalized frequency response function (GFRF) and the higher order sinusoidal input describing function (HOSIDF) for polynomial Wiener–Hammerstein systems are explicitly related, assuming the linear dynamics are known. Necessary and sufficient conditions for this relation to exist and results on the uniqueness and equivalence of the HOSIDF and GFRF are provided. Finally, this yields an efficient computational procedure for computing the GFRF from the HOSIDF and vice versa.     

Explaining the segmentation effect in learning from animations: The role of pausing and temporal cueing

Segmentation of animations, that is presenting them in pieces rather than as a continuous stream of information, has been shown to have a beneficial effect on cognitive load and learning for novices. Two different explanations of this segmentation effect have been proposed. Firstly, pauses are usually inserted between the segments, which may give learners extra time to perform necessary cognitive processes. Secondly, because segmentation divides animations into meaningful pieces, it provides a form of temporal cueing which may support learners in perceiving the underlying structure of the process or procedure depicted in the animation. This study investigates which of these explanations is the most plausible. Secondary education students (N = 161) studied animations on probability calculation, after having been randomly assigned to one of four conditions: non-segmented animations, animations segmented by pauses only, animations segmented by temporarily darkening the screen only, and animations segmented by both pauses and temporarily darkening the screen. The results suggest that both pauses and cues play a role in the segmentation effect, but in a different way.